[Federal Register Volume 89, Number 90 (Wednesday, May 8, 2024)]
[Rules and Regulations]
[Pages 38950-39122]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-09157]



[[Page 38949]]

Vol. 89

Wednesday,

No. 90

May 8, 2024

Part II





Environmental Protection Agency





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40 CFR Parts 9 and 257





Hazardous and Solid Waste Management System: Disposal of Coal 
Combustion Residuals From Electric Utilities; Legacy CCR Surface 
Impoundments; Final Rule

  Federal Register / Vol. 89, No. 90 / Wednesday, May 8, 2024 / Rules 
and Regulations  

[[Page 38950]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9 and 257

[EPA-HQ-OLEM-2020-0107; FRL-7814-04-OLEM]
RIN 2050-AH14


Hazardous and Solid Waste Management System: Disposal of Coal 
Combustion Residuals From Electric Utilities; Legacy CCR Surface 
Impoundments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: On April 17, 2015, the Environmental Protection Agency (EPA or 
the Agency) promulgated national minimum criteria for existing and new 
coal combustion residuals (CCR) landfills and existing and new CCR 
surface impoundments. On August 21, 2018, the United States Court of 
Appeals for the District of Columbia Circuit vacated the exemption for 
inactive surface impoundments at inactive facilities (legacy CCR 
surface impoundments) and remanded the issue back to EPA to take 
further action consistent with its opinion in Utility Solid Waste 
Activities Group, et al. v. EPA. This action responds to that order and 
establishes regulatory requirements for legacy CCR surface 
impoundments. EPA is also establishing requirements for CCR management 
units at active CCR facilities and at inactive CCR facilities with a 
legacy CCR surface impoundment. Finally, EPA is making several 
technical corrections to the existing regulations, such as correcting 
certain citations and harmonizing definitions.

DATES: This final rule is effective on November 4, 2024.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OLEM-2020-0107. All documents in the docket are listed on 
the http://www.regulations.gov website. Although listed in the index, 
some information is not publicly available, e.g., CBI or other 
information whose disclosure is restricted by statute. Certain other 
material, such as copyrighted material, is not placed on the internet 
and will be publicly available only in hard copy form. Publicly 
available docket materials are available electronically through http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: For questions concerning this 
proposal, contact Michelle Lloyd, Office of Resource Conservation and 
Recovery, Materials Recovery and Waste Management Division, 
Environmental Protection Agency, 1200 Pennsylvania Avenue NW, MC: 
5304T, Washington, DC 20460; telephone number: (202) 566-0560; email 
address: [email protected], or Taylor Holt, Office of Resource 
Conservation and Recovery, Materials Recovery and Waste Management 
Division, Environmental Protection Agency, 1200 Pennsylvania Avenue NW, 
MC: 5304T, Washington, DC 20460; telephone number: (202) 566-1439; 
email address: [email protected]. For more information on this 
rulemaking, please visit https://www.epa.gov/coalash.

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. General Information
    A. Does this action apply to me?
    B. What action is the Agency taking?
    C. What is the Agency's authority for taking this action?
    D. What are the incremental costs and benefits of this action?
II. Background
    A. 2015 CCR Rule
    B. 2018 USWAG Decision
    C. 2020 Part B Proposed Rule
    D. 2020 Advance Notice of Proposed Rulemaking
    E. 2023 Proposed Rule and Comments
    F. 2023 Notice of Data Availability
III. What is EPA finalizing?
    A. Risks From Legacy CCR Surface Impoundments and CCR Management 
Units
    1. Summary of May 2023 Proposal
    2. 2023 Draft Risk Assessment
    3. Response to Comments on the Proposal and the NODA
    4. 2024 Final Risk Assessment
    B. Legacy CCR Surface Impoundment Requirements
    1. Definition of a ``Legacy CCR Surface Impoundment''
    2. Applicable Requirements for Legacy CCR Surface Impoundments 
and Compliance Deadlines
    C. CCR Management Unit Requirements
    1. Damage Cases
    2. Applicability and Definitions Related to CCR Management Units
    3. Facility Evaluation for Identifying CCR Management Units
    4. Applicable Requirements for CCR Management Units and 
Compliance Deadlines
    D. Closure of CCR Units by Removal of CCR
    1. Background
    2. March 2020 Proposed Rule
    3. What is EPA Finalizing Related to the March 2020 Proposed 
Rule
    E. Technical Corrections
IV. Effect on State CCR Permit Programs
V. The Projected Economic Impact of This Action
    A. Introduction
    B. Affected Universe
    C. Baseline Costs
    D. Costs and Benefits of the Final Rule
    VI. Statutory and Executive Order Reviews
    Regulatory Text

List of Acronyms

ACM Assessment of Corrective Measures
ANPRM Advance Notice of Proposed Rulemaking
ARAR applicable or relevant and appropriate requirements
ASD alternative source demonstration
CAA Clean Air Act
CBI Confidential Business Information
CBR closure by removal
CCR coal combustion residuals
CCRMU coal combustion residuals management unit
CERCLA Comprehensive Environmental Response, Compensation, and 
Liability Act
CIP closure in place
CFR Code of Federal Regulations
COALQUAL U.S. Geological Survey coal quality database
CWA Clean Water Act
DOE Department of Energy
EAP Emergency Action Plan
EIA Energy Information Administration
EIP Environmental Integrity Project
EJ environmental justice
ELG Effluent Limitation Guidelines
EPA Environmental Protection Agency
EPACMTP EPA Composite Model for Leachate Migration with 
Transformation Products
EPRI Electric Power Research Institute
FER Facility Evaluation Report
FERC Federal Energy Regulatory Commission
FGD flue gas desulfurization
FR Federal Register
GWMCA groundwater monitoring and corrective action
GWPS groundwater protection standard
HQ hazard quotient
HSWA Hazardous and Solid Waste Amendments
ICR Information Collection Request
IRIS Integrated Risk Information System
LEAF Leaching Environmental Assessment Framework
MCL maximum contaminant level
MDE Maryland Department of the Environment
MNA monitored natural attenuation
MODFLOW-USG Modular Three-Dimension Finite-Difference Ground-Water 
Flow Model
MSW Municipal Solid Waste
MW Megawatts
NAICS North American Industry Classification System
NERC North American Electric Reliability Corporation
NODA notice of data availability
NPDES National Pollution Discharge Elimination System
NPL National Priorities List
NTTAA National Technology Transfer and Advancement Act
OAFU Other Active Facilities
OLEM Office of Land and Emergency Management
OMB Office of Management and Budget
OSHA Occupational Safety and Health Administration

[[Page 38951]]

P.E. Professional Engineer
PM particulate matter
PRA Paperwork Reduction Act
PRG preliminary remediation goal
PUC Public Utility Commission
QA/QC quality assurance/quality control
RCRA Resource Conservation and Recovery Act
RIA Regulatory Impact Analysis
RME reasonable maximum exposure
RTO Regional Transmission Organizations
SMCL secondary maximum contaminant level
SSI statistically significant increase
SSL statistically significant level
TDS total dissolved solids
TSCA Toxic Substances Control Act
TSDF Transportation Storage and Disposal Facility
TVA Tennessee Valley Authority
UMRA Unfunded Mandates Reform Act
USGS U.S. Geological Survey
USWAG Utility Solid Waste Activities Group
WIIN Water Infrastructure Improvements for the Nation
WQC water quality criteria

I. General Information

A. Does this action apply to me?

    This rule applies to and may affect all CCR generated by electric 
utilities and independent power producers that fall within the North 
American Industry Classification System (NAICS) code 221112. The 
reference to NAICS code 221112 is not intended to be exhaustive, but 
rather provides a guide for readers regarding entities likely to be 
regulated by this action. This discussion lists the types of entities 
that EPA is now aware could potentially be regulated by this action. 
Other types of entities not described here could also be regulated. To 
determine whether your entity is regulated by this action, you should 
carefully examine the applicability criteria found in 40 CFR 257.50 of 
title 40 of the Code of Federal Regulations. If you have questions 
regarding the applicability of this action to a particular entity, 
consult the person listed in the FOR FURTHER INFORMATION CONTACT 
section.

B. What action is the Agency taking?

    EPA is amending the regulations governing the disposal of CCR in 
landfills and surface impoundments, codified in subpart D of part 257 
of Title 40 of the Code of Federal Regulations (CFR) (CCR regulations). 
Specifically, the Agency is establishing regulatory requirements for 
inactive CCR surface impoundments at inactive utilities (``legacy CCR 
surface impoundment'' or ``legacy impoundment''). This action is being 
taken in response to the August 21, 2018, opinion by the U.S. Court of 
Appeals for the District of Columbia Circuit in Utility Solid Waste 
Activities Group v. EPA, 901 F.3d 414 (D.C. 2018) (``USWAG decision'' 
or ``USWAG'') that vacated and remanded the provision exempting legacy 
impoundments from the CCR regulations. This action includes adding a 
definition for legacy CCR surface impoundments and other terms relevant 
to this rulemaking. It also requires that legacy CCR surface 
impoundments comply with certain existing CCR regulations with tailored 
compliance deadlines.
    While this action is responsive to the D.C. Circuit's order, it is 
also driven by the record, which clearly demonstrates that regulating 
legacy CCR surface impoundments will have significant quantified and 
unquantified public health and environmental benefits. As EPA concluded 
in 2015, the risks posed by unlined CCR surface impoundments are 
substantial, and the risks from legacy impoundments are at least as 
significant. EPA's 2014 Risk Assessment concluded that the cancer risks 
from unlined surface impoundments ranged from 3 x 10-\4\ for 
trivalent arsenic to 4 x 10-\5\ for pentavalent arsenic. 
Non-cancer risks from these same units also significantly exceeded 
EPA's level of concern, with estimated Hazard Quotients (HQ) of two for 
thallium, three for lithium, four for molybdenum and eight for 
trivalent arsenic. In addition, as described in Unit III.A.1 of this 
preamble, information obtained since 2015 indicates that the risks for 
legacy CCR surface impoundments are likely to be greater than EPA 
originally estimated. Finally, based on the demographic composition and 
environmental conditions of communities within one and three miles of 
legacy CCR surface impoundments, this final rule will reduce existing 
disproportionate and adverse effects on economically vulnerable 
communities, as well as those that currently face environmental 
burdens. For example, in Illinois the population living within one mile 
of legacy CCR surface impoundment sites is over three times as likely 
compared to the State average to have less than a high school education 
(35.66% compared to 10.10%, see Regulatory Impact Analysis (RIA) 
exhibit ES.14), and that population already experiences higher than 
average exposures to particulate matter, ozone, diesel emissions, 
lifetime air toxics cancer risks, and proximity to traffic, Superfund 
sites, Risk Management Plan sites, and hazardous waste facilities (see 
RIA exhibit ES.15). Consistent with the directive in section 4004(a) to 
ensure that the statutory standard is met at all regulated sites, 
including the most vulnerable, this final rule will help EPA further 
ensure that the communities and ecosystems closest to coal facilities 
are sufficiently protected from harm from groundwater contamination, 
surface water contamination, fugitive dust, floods and impoundment 
overflows, and threats to wildlife.
    EPA is also establishing requirements to address the risks from 
currently exempt solid waste management that involves the direct 
placement of CCR on the land. EPA is extending a subset of the existing 
requirements in 40 CFR part 257, subpart D to CCR surface impoundments 
and landfills that closed prior to the effective date of the 2015 CCR 
Rule, inactive CCR landfills, and other areas where CCR is managed 
directly on the land. In this action, EPA refers to these as CCR 
management units, or CCRMU. The final rule expands the CCRMU 
requirements to a set of active facilities that were not regulated by 
the 2015 CCR rule because they had ceased disposing of CCR in their on-
site disposal units, and they did not have an inactive surface 
impoundment. Accordingly, this rule applies to all CCRMU at active CCR 
facilities and inactive facilities with a legacy CCR surface 
impoundment.
    EPA is also finalizing alternative closure provisions to allow a 
facility to complete the closure by removal in two stages: first, by 
completing all removal and decontamination procedures; and second, by 
completing all groundwater remediation in a separate post closure care 
period.
    Finally, EPA is making a number of technical corrections to the 
existing regulations, such as correcting certain citations and 
harmonizing definitions.
    EPA intends the provisions of the rule to be severable. In the 
event that any individual provision or part of the rule is invalidated, 
EPA intends that this would not render the entire rule invalid, and 
that any individual provisions that can continue to operate will be 
left in place. For example, EPA intends that the provisions governing 
each class of facilities--legacy CCR inactive surface impoundments, CCR 
management units, other active facility units, and regulated CCR 
landfills containing waste in contact with groundwater--to be 
independently severable from one another as each set of requirements 
operates independently from the other.
    Likewise, the provisions regulating existing units at active 
facilities, including those units at non-fossil-fuel-fired facilities 
generating energy, are severable from the other substantive 
requirements--each provision may continue operating even if one of the 
others is invalidated. EPA also intends

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that, within each set of provisions for legacy CCR surface impoundments 
and for CCR management units, the substantive requirements be severable 
from each other. For example, if any of the closure requirements were 
to be set aside (e.g., the requirement that CCRMU initiate closure 
within 48 months of publication), the groundwater monitoring and 
corrective action requirements can continue to fully and effectively 
operate. These requirements function independently from each other, 
address environmental concerns through different means, and are not 
dependent on the others; they are therefore severable from each other. 
Lastly, as set forth below, EPA has deferred the dates by when some 
units in some circumstances must comply with the substantive standards 
governing legacy CCR surface impoundments and CCR management units. If 
any of the deferrals were to be set aside, EPA intends that the 
substantive standards would remain in place because the rationale for 
and effectiveness of each set of substantive standards is not dependent 
on any of the deferrals.
    For the reader's convenience, EPA has provided a background 
description of existing requirements in several places throughout this 
preamble.

C. What is the Agency's authority for taking this action?

    EPA is publishing this notice under the authority of sections 
1008(a), 2002(a), 3007, 4004, and 4005(a) and (d) of the Solid Waste 
Disposal Act of 1970, as amended by the Resource Conservation and 
Recovery Act of 1976 (RCRA), as amended by the Hazardous and Solid 
Waste Amendments of 1984 (HSWA) and the Water Infrastructure 
Improvements for the Nation (WIIN) Act of 2016, 42 U.S.C. 6907(a), 
6912(a), 6927, 6944, 6945(a) and (d).
    RCRA section 1008(a) authorizes EPA to publish ``suggested 
guidelines for solid waste management.'' 42 U.S.C. 6907(a). RCRA 
defines solid waste management as ``the systematic administration of 
activities which provide for the collection, source separation, 
storage, transportation, transfer, processing, treatment, and disposal 
of solid waste.'' 42 U.S.C. 6903(28).
    Pursuant to section 1008(a)(3), the guidelines are to include the 
minimum criteria to be used by the States to define the solid waste 
management practices that constitute the open dumping of solid waste or 
hazardous waste and are prohibited as ``open dumping'' under section 
4005. Only those requirements promulgated under the authority of 
section 1008(a)(3) are enforceable under section 7002 of RCRA.
    RCRA section 4004(a) generally requires EPA to promulgate 
regulations containing criteria distinguishing ``sanitary landfills,'' 
which may continue to operate, from ``open dumps,'' which are 
prohibited. 42 U.S.C. 6944(a); see id. 6903(14), (26); 6945(a). The 
statute directs that, ``at a minimum, the criteria are to ensure that 
units are classified as sanitary landfills only if there is no 
reasonable probability of adverse effects on health or the environment 
from disposal of solid wastes at such facility.'' 42 U.S.C. 6944(a).
    RCRA section 4005(a), entitled ``Closing or upgrading of existing 
open dumps,'' prohibits any solid waste management practices or 
disposal of solid waste that does not comply with EPA regulations 
issued under RCRA section 1008(a) and 4004(a). 42 U.S.C. 6945(a). See 
also 42 U.S.C. 6903(14) (definition of ``open dump''). This prohibition 
takes effect ``upon promulgation'' of any rules issued under section 
1008(a)(3) and is enforceable either through a citizen suit brought 
pursuant to section 7002, or through an EPA enforcement action brought 
pursuant to section 4005(d)(4)(A). See 42 U.S.C. 6945(a), (d)(4)(A) 
(authorizing EPA to use the authority under RCRA section 3008(a) to 
enforce the open dumping prohibition for CCR). RCRA section 4005(a) 
also directs that open dumps (i.e., facilities out of compliance with 
EPA's criteria), must be closed or upgraded. See 42 U.S.C. 6945(a).
    RCRA section 4005(d)(3) specifies that the regulations in 40 CFR 
part 257, subpart D ``(or successor regulations promulgated pursuant to 
sections 6907(a)(3) and 6944(a) of this title), shall apply to each CCR 
unit'' unless a permit issued by an approved State or by EPA is in 
effect. Similarly, section 4005(d)(6) \1\ provides that:
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    \1\ 42 U.S.C. 6945(d)(6).

a CCR unit shall be considered to be a sanitary landfill for 
purposes of this chapter, including subsection (a), only if the coal 
combustion residuals unit is operating in accordance with [a permit 
issued by EPA or an approved State] or the applicable criteria for 
coal combustion residuals units under part 257 of title 40, Code of 
Federal Regulations (or successor regulations promulgated pursuant 
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to sections 6907(a)(3) and 6944(a) of this title).

1. Regulation of Solid Wastes Under RCRA Subtitle D
    Solid wastes that are neither a listed nor characteristic hazardous 
waste are subject to the requirements of RCRA subtitle D. Subtitle D of 
RCRA establishes a framework for Federal, State, and local government 
cooperation in controlling the management of nonhazardous solid waste. 
The Federal role is to establish the overall regulatory direction by 
providing minimum nationwide standards that will protect human health 
and the environment. States may, but are not required to, adopt these 
requirements into their State programs.
    Under RCRA section 4005(a), upon promulgation of criteria under 
section 1008(a)(3), any solid waste management practice or disposal of 
solid waste that constitutes the ``open dumping'' of solid waste is 
prohibited. The Federal standards apply directly to the facility (are 
self-implementing) and facilities are directly responsible for ensuring 
that their operations comply with these requirements.
    RCRA section 4005(d) establishes an additional regulatory 
structure, applicable exclusively to the solid waste management of CCR, 
that builds on the provisions in sections 1008(a)(3), 4004, and 
4005(a), without restricting the scope of EPA's authority under those 
sections. See, 42 U.S.C. 6945 (d)(7). Under 4005(d), States may seek 
EPA approval of a State permitting program under which individualized 
facility permits would ``operate in lieu of [EPA] regulation of coal 
combustion residuals units in the State.'' 42 U.S.C. 6945(d)(1)(A). EPA 
is also directed to ``implement a permit program,'' which would operate 
in absence of an approved State program. 42 U.S.C. 6945(d)(2). However, 
the statute makes clear that facilities must continue to comply with 
the Federal regulations until a permit issued by either EPA or an 
approved State is in effect. 42 U.S.C. 6945(d)(3), (6).
    RCRA sections 1008(a)(3) and 4004(a) delegate broad authority to 
EPA to establish regulations governing the management of solid waste. 
Under section 4004(a) EPA is charged with establishing requirements to 
ensure that facilities will be classified as sanitary landfills and not 
an open dump ``only if there is no reasonable probability of adverse 
effects on health or the environment from the disposal of solid waste'' 
at the facility. Or in other words, under section 4004(a) EPA is 
charged with issuing regulations to address all ``reasonable 
probabilities of adverse effects'' (i.e., all reasonably anticipated 
risks) to health and the environment from the disposal of solid waste. 
Section 1008(a)(3) expands EPA's authority to address the risks from 
any of the activities identified as ``solid waste management'' in RCRA 
section

[[Page 38953]]

1004(28). Specifically, EPA is authorized to establish requirements 
applicable to ``storage, transportation, transfer, processing, 
treatment, and disposal of solid waste.'' (42 U.S.C. 6907(a), 
6903(28)). Under RCRA, EPA sets these requirements without taking cost 
into account as a factor. See USWAG et al. v. EPA, 901 F.3d at 448-49 
(citing RCRA section 4004(a)).
    The statute is clear that EPA is authorized to issue regulations to 
address the current risks from previous solid waste management 
activities. EPA explained at length the basis for this conclusion as 
part of the Agency's rationale for regulating inactive impoundments. 
See, 80 FR 21344--21347. See also USWAG, 901 F.3d at 440. Among other 
provisions, the statutory definition of an ``open dump'' conclusively 
resolves the question. RCRA defines an ``open dump'' as ``any facility 
or site where solid waste is disposed of . . . .'' 42 U.S.C. 6903(14). 
As the D.C. Circuit explained,

    Importantly, while the ``is'' retains its active present tense, 
the ``disposal'' takes the form of a past participle (``disposed''). 
In this way, the disposal itself can exist (it ``is''), even if the 
act of disposal took place at some prior time . . . . Properly 
translated then, an open dump includes any facility (other than a 
sanitary landfill or hazardous waste disposal facility), where solid 
waste still ``is deposited,'' ``is dumped,'' ``is spilled,'' ``is 
leaked,'' or ``is placed,'' regardless of when it might have 
originally been dropped off. See 42 U.S.C. 6903(3), (14). In other 
words, the waste in inactive impoundments ``is disposed of'' at a 
site no longer receiving new waste in just the same way that it ``is 
disposed of'' at a site that is still operating.

901 F.3d at 440. See also In re Consolidated Consol. Land Disposal 
Regulation Litig., 938 F.2d 1386, 1389 (D.C. Cir. 1991) (EPA's reading 
of the term ``disposal'' in RCRA's subtitle C, 42 U.S.C. 6924, to 
include ``the continuing presence of waste'' was reasonable); USWAG, 
901 F.3d at 453-54 (Henderson, J., concurring) (same). By the same 
logic, these provisions would authorize EPA to regulate closed units 
that continue to pose risks to health or the environment, for example 
by requiring the owners or operators of such units to remediate any 
contamination from these units, or to take action to prevent such 
contamination.
    The 2016 amendments further confirm EPA's authority over these 
activities. In section 4005, Congress referenced the 2015 regulations 
in the statute, and expressly stated that the amendments in 4005(d) 
were not intended to limit or restrict the authority already provided 
under sections 1008(a)(3) and 4004(a). See, 42 U.S.C. 6945(d)(3), (6), 
(7). By incorporating the rule into the statute without modification, 
Congress has affirmed the Agency's authority to impose the kind of 
requirements established in part 257 (e.g., corrective action to 
remediate groundwater contamination). Moreover, Congress made clear 
that EPA retains the authority to modify or expand these requirements 
as necessary to ensure that the standard in section 4004(a) will 
continue to be met. See, e.g., 42 U.S.C. 6945(d)(1)(A)(i), (3), (6) 
(referencing ``or successor regulations promulgated pursuant to 
sections 6907(a)(3) and 6944(a) of this title'').
    EPA interprets the standard in section 4004(a) to apply equally to 
criteria issued under sections 1008(a)(3) and 4004(a); namely that the 
criteria must ensure that a facility is to be classified as a sanitary 
landfill, and thus allowed to continue to operate, ``only if there is 
no reasonable probability of adverse effects on health or the 
environment'' from either the disposal or other solid waste management 
practices at the facility. Thus, under the combined authority conferred 
by sections 1008(a)(3) and 4004(a), a facility is an ``open dump'' if 
it engages in any activity involving the management of solid waste that 
does not meet the standard in section 4004(a); or in other words, any 
activity involved with the management of solid waste that presents a 
reasonable probability of causing adverse effects on health or the 
environment. EPA also interprets these provisions to authorize the 
establishment of criteria that define the manner in which facilities 
upgrade or close, consistent with the standard in section 4004(a), to 
ensure there will be no reasonable probability of adverse effects on 
health or the environment.

D. What are the incremental costs and benefits of this action?

    As noted previously, EPA establishes the requirements under RCRA 
sections 1008(a)(3) and 4004(a) without taking cost into account. See, 
USWAG, 901 F.3d at 448-49. The following cost estimates are presented 
in the RIA and summarized in this preamble for compliance with OMB 
Circular A-4, E.O. 12866, and E.O. 14094. The requirements in this rule 
do not rely on these cost estimates.\2\
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    \2\ Although EPA did not consider costs in developing this rule, 
if the Agency had considered costs, the final rule would not have 
been different. As discussed in greater detail later in this 
preamble and in the RIA, the monetized benefits are based on only a 
subset of adverse health effects from a single constituent. EPA 
monetized the benefit from two additional human health endpoints 
associated with that single constituent in a sensitivity analysis 
and estimated an additional $19 million per year when discounting at 
2% from that single contaminant. The RIA also describes a number of 
important benefits that cannot currently be quantified or monetized 
due to data limitations or limitations in current methodologies. 
Based on these estimates EPA believes that after considering all 
unquantified and distributional effects, the public health and 
welfare gains that will result from the proposed alternative would 
justify the rule's costs.
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    The RIA estimates that the annualized monetized costs of this 
action will be approximately $214-$240 million per year when 
discounting at 2%. Of this, $123-$135 million is attributable to the 
requirements for legacy CCR surface impoundments, which are subject to 
the D.C. Circuit's order in USWAG, $79-$92 million is attributable to 
the requirements for CCRMU, an additional $8-$9 million is attributable 
to the requirements for CCRMU at Other Active Facilities (OAFUs) (a 
term used in the RIA) that are discussed in Unit III.C.2.e of the 
preamble, and $4 million is attributable to requirements for landfills. 
The costs of this final rule are discussed further in the RIA and 
include the costs of unit closure, corrective action, fugitive dust 
controls, structural integrity inspections, and recordkeeping and 
reporting.
    The RIA estimates that the annualized monetized benefits 
attributable to this action will be approximately $53-$80 million per 
year when discounting at 2%. Of this, $43-$57 million is attributable 
to the requirements for legacy CCR surface impoundments, $9-$21 million 
is attributable to the requirements for CCRMU, $1-$2 million is 
attributable to the requirements for CCRMU at ``other active 
facilities,'' or OAFUs. Requirements for landfills account for a de 
minimis amount of benefits.
    In addition to monetized benefits, the RIA describes ten categories 
of non-monetized benefits. These include human health effects from lead 
exposure such as ADHD, cardiovascular mortality, and increased cancer 
risk. They also include ecosystem benefits from avoided exposure to the 
heavy metals in CCR effluent. The RIA describes several property-
related benefits including increased property values near closed and 
remediated CCR units, and option values for remediated land. The RIA 
also contextualizes the final rule within EPA's broader efforts to 
regulate air and surface water pollution from coal fired power plants.
    Further information on the economic effects of this action can be 
found in Unit V of this preamble.

[[Page 38954]]

II. Background

A. 2015 CCR Rule

    On April 17, 2015, EPA finalized national minimum criteria for the 
disposal of CCR as solid waste under Subtitle D of RCRA titled, 
``Hazardous and Solid Waste Management System; Disposal of Coal 
Combustion Residuals from Electric Utilities'' (80 FR 21302) (2015 CCR 
Rule). The 2015 CCR Rule, codified in 40 CFR part 257, subpart D, 
established regulations for existing and new CCR landfills, as well as 
existing and new CCR surface impoundments (including all lateral 
expansions of CCR units). The criteria consist of location 
restrictions, design and operating criteria, groundwater monitoring and 
corrective action requirements, closure and post-closure care 
requirements, recordkeeping, notification, and internet posting 
requirements.
    The 2015 CCR Rule also imposed requirements on inactive surface 
impoundments at active facilities. A CCR surface impoundment is a 
natural topographic depression, man-made excavation, or diked area, 
which is designed to hold an accumulation of CCR and liquids, and the 
unit treats, stores, or disposes of CCR. The 2015 CCR Rule defined an 
``inactive CCR surface impoundment'' as ``a CCR surface impoundment 
that no longer receives CCR on or after October 19, 2015, and still 
contains both CCR and liquids on or after October 19, 2015.'' 40 CFR 
257.53. The rule defined ``active facility or active electric utilities 
or independent power producers'' as ``any facility subject to the 
requirements of this subpart that is in operation on October 19, 2015. 
An electric utility or independent power producer is in operation if it 
is generating electricity that is provided to electric power 
transmission systems or to electric power distribution systems on or 
after October 19, 2015. An off-site disposal facility is in operation 
if it is accepting or managing CCR on or after October 19, 2015.'' 40 
CFR 257.53.
    The 2015 CCR Rule did not impose any requirements on inactive 
facilities. EPA explained that this was consistent with past decisions 
under RCRA subtitle C. See, 80 FR 21344 (April 17, 2015). EPA further 
raised concerns that it would be difficult to identify the owners or 
other parties responsible for such facilities, as well as concerns that 
the present owner of the land on which an inactive facility was located 
might have no connection (other than present ownership of the land) 
with the prior disposal activities. Id. Consequently, EPA exempted 
those units at Sec.  257.50(e).

B. 2018 USWAG Decision

    The 2015 CCR Rule was challenged by several parties, including 
coalitions of regulated entities and environmental organizations 
(``Environmental Petitioners''). See USWAG et al. v. EPA, 901 F.3d 414 
(D.C. Cir. 2018). Environmental Petitioners raised two challenges that 
are relevant to this final rule. First, they challenged the provision 
at Sec.  257.101(a)(1) that allowed existing, unlined surface 
impoundments to continue to operate until they exceeded the groundwater 
protection standard. They contended that EPA failed to show how 
continued operation of unlined impoundments met RCRA's baseline 
requirement that any solid waste disposal site pose ``no reasonable 
probability of adverse effects on health or the environment.'' 42 
U.S.C. 6944(a). Second, Environmental Petitioners challenged the 
exemption at Sec.  257.50(e) for inactive surface impoundments at 
inactive power plants (i.e., ``legacy ponds''). Environmental 
Petitioners argued that legacy ponds are at risk of unmonitored leaks 
and catastrophic structural failures.
    On August 21, 2018, the U.S. Court of Appeals for the D.C. Circuit 
upheld most of the 2015 CCR Rule but decided in favor of Environmental 
Petitioners on these two claims. The Court held that EPA acted 
``arbitrarily and capriciously and contrary to RCRA'' in failing to 
require the closure of unlined surface impoundments \3\ and in 
exempting inactive surface impoundments at inactive power plants from 
regulation. The Court vacated these provisions and remanded the matter 
back to the Agency for further action consistent with its opinion.
---------------------------------------------------------------------------

    \3\ After the Court's ruling, the closure of unlined CCR surface 
impoundments was addressed in a separate regulatory action that was 
published on August 28, 2020 (85 FR 53516).
---------------------------------------------------------------------------

    In overturning the exemption for legacy ponds, the Court evaluated 
the evidence in the rulemaking record and reached specific conclusions 
about the risks that legacy ponds pose based on the record for the 2015 
CCR Rule. The Court pointed to evidence that legacy ponds are most 
likely to be unlined and unmonitored and that such units have been 
shown to be more likely to leak than units at utilities still in 
operation. 901 F.3d at 432. The Court also determined that legacy 
ponds:

. . . pose the same substantial threats to human health and the 
environment as the riskiest Coal Residuals disposal methods, 
compounded by diminished preventative and remediation oversight due 
to the absence of an onsite owner and daily monitoring. See 80 FR at 
21343 through 21344 (finding that the greatest disposal risks are 
``primarily driven by the older existing units, which are generally 
unlined''). Notably, this very Rule was prompted by a catastrophic 
legacy pond failure that resulted in a ``massive'' spill of 39,000 
tons of coal ash and 27 million gallons of wastewater into North 
Carolina's Dan River. . . .
    [T]here is no gainsaying the dangers that unregulated legacy 
ponds present. The EPA itself acknowledges the vital importance of 
regulating inactive impoundments at active facilities. That is 
because, if not properly closed, those impoundments will 
``significant[ly]'' threaten ``human health and the environment 
through catastrophic failure'' for many years to come. 75 FR at 
35,177; see also 80 FR at 21,344 n. 40.
    The risks posed by legacy ponds are at least as substantial as 
inactive impoundments at active facilities. See 80 FR at 21,343-21, 
344 (finding ``no [ ] measurabl[e] differen[ce]'' in risk of 
catastrophic events between active and inactive impoundments). And 
the threat is very real. Legacy ponds caused multiple human and 
environmental disasters in the years leading up to the Rule's 
promulgation. See 75 FR at 35,147 (proposed rule discusses multiple 
serious incidents). For example, a pipe break at a legacy pond at 
the Widows Creek plant in Alabama caused 6.1 million gallons of 
toxic slurry to deluge local waterways. Id. Another legacy pond in 
Gambrills, Maryland caused the heavy metal contamination of local 
drinking water. Id. And the preamble to the Rule itself specifically 
points to the catastrophic spill at the Dan River legacy pond in 
North Carolina. 80 FR at 21,393-21,394.

Id. at 432-433. Relying on this evidence, the Court concluded there was 
no logical basis for distinguishing between the inactive impoundments 
at active facilities that were regulated and the legacy impoundments 
that were exempt. Id. at 434. Consequently, the Court vacated the 
provision of the 2015 CCR Rule (Sec.  257.50(e)) that specifically 
exempted inactive impoundments at inactive facilities from regulation 
and remanded the matter back to EPA for further action consistent with 
its opinion. Notwithstanding the vacatur of Sec.  257.50(e), until EPA 
amended the regulations to effectuate the Court's order, facilities 
were not legally obliged to take any action to comply with the Federal 
CCR regulations. This is because, as originally drafted, legacy CCR 
surface impoundments did not fall within the scope of the rule, as 
defined in Sec.  257.50. The specific provision in Sec.  257.50(e) 
exempting legacy impoundments merely identified the units that were not 
covered by Sec.  257.50(b). Because the vacatur of Sec.  257.50(e) did 
not amend Sec.  257.50(b), legacy impoundments remained exempt.

[[Page 38955]]

C. 2020 Part B Proposed Rule

    In the March 3, 2020 proposed rule, Hazardous and Solid Waste 
Management System: Disposal of CCR; A Holistic Approach to Closure Part 
B: Alternate Demonstration for Unlined Surface Impoundments; 
Implementation of Closure (85 FR 12456), EPA proposed revisions to the 
2015 CCR Rule, including: procedures to allow facilities to request 
approval to use an alternate liner for CCR surface impoundments; two 
alternative proposed options to allow the use of CCR during unit 
closure; an additional closure option for CCR units being closed by 
removal of CCR; and requirements for annual closure progress reports. 
On November 12, 2020, EPA finalized the procedures to allow facilities 
to request approval to use an alternate liner for CCR surface 
impoundments. 85 FR 72506. In this final rule, the Agency is taking 
final action on the proposed closure option for units being closed by 
removal of CCR, which action is discussed in Unit III.D of this 
preamble. EPA is still considering provisions from the proposed rule 
that are not addressed in this rule and may be addressed in a 
subsequent action.

D. 2020 Advance Notice of Proposed Rulemaking

    On October 14, 2020, EPA published an Advance Notice of Proposed 
Rulemaking (ANPRM) (85 FR 65015). In that action, EPA requested 
information related to legacy CCR surface impoundments to inform a 
future rulemaking. The Agency requested input on its regulatory 
authority, input on a potential definition of a legacy CCR surface 
impoundment and specific information on the types of inactive surface 
impoundments at inactive facilities that might be considered legacy CCR 
surface impoundments. Specifically, EPA requested information on how 
many of these units exist, the current status of these units (e.g., 
capped, dry, closed according to State requirements, still holding 
water), and the names, locations, and closure dates of former power 
plants that may have these units. Finally, the Agency took comment on 
which CCR regulations should apply to legacy CCR surface impoundments 
and on suggestions for compliance deadlines.
    During the 60-day public comment period, the Agency received over 
15,000 comments from environmental groups, four States, one Tribe, 
individual utilities, and industry trade associations. The topics 
raised in comments included a potential definition of a legacy CCR 
surface impoundment, EPA's regulatory authority, the scope and 
applicability of the legacy impoundment rule, and regulatory 
requirements to propose. Moreover, the comments generally agreed that 
EPA must prescribe timeframes for coming into compliance with the 
regulations and they recommended timeframes that are shorter than 
compliance timeframes in the 2015 CCR Rule.
    As noted in the ANPRM, EPA took comment on whether, in light of the 
Court's opinion in USWAG, the Agency could reconsider whether it has 
the authority to regulate inactive impoundments under RCRA subtitle D. 
85 FR 65017-65018 (October 14, 2020). The general consensus from 
commenters on the ANPRM was that, because the Court resolved the 
question based on the plain meaning of the statute, EPA does not have 
the discretion to reinterpret its authority. In addition, no commenter 
identified a factual basis for not regulating legacy CCR surface 
impoundments that addressed the Court's concern about the risks these 
units pose. Id. at 65018. Consequently, EPA is not revisiting the 
question of whether it may regulate inactive or legacy CCR surface 
impoundments.

E. 2023 Proposed Rule and Comments

    On May 18, 2023, EPA proposed revisions to the CCR regulations (88 
FR 31982) (``the proposed rule'' or ``2023 proposed rule''). These 
revisions included establishing regulations specifying that legacy CCR 
surface impoundments are subject to 40 CFR part 257, subpart D and 
specifying that owners or operators of legacy CCR surface impoundments 
comply with all the appropriate requirements applicable to inactive CCR 
surface impoundments at active facilities. In addition, EPA proposed to 
establish requirements to address the risks from currently exempt solid 
waste management that involves the direct placement of CCR on the land. 
EPA proposed to extend a subset of the existing requirements in part 
257, subpart D to CCRMU, which was proposed to include CCR surface 
impoundments and landfills that closed prior to the effective date of 
the 2015 CCR Rule, inactive CCR landfills, and other areas where CCR is 
managed directly on the land. This proposal would apply to all active 
CCR facilities and all inactive facilities with legacy CCR surface 
impoundments. Lastly, EPA proposed to make several technical 
corrections to the CCR regulations. These are: (1) To clarify the 
definitions of ``feasible'' and ``technically feasible''; (2) To 
correct the CFR reference in the definition of wetlands at Sec.  
257.61(a); (3) To correct a reference in the groundwater monitoring 
scope section; (4) To standardize the references to CCR websites 
throughout the CCR regulations; and (5) EPA requested comment on 
extending the period for document retention and posting.
    The Agency received over 33,500 comments on the proposed rule, with 
over 600 unique comments. Commenters included individual electric 
utilities and independent power producers, national trade associations, 
State agencies, public interest and environmental groups, private 
citizens, and entities involved with the beneficial use of CCR. All 
public comments submitted in response to the proposal can be found in 
the docket for this action. Most commenters focused on the scope of the 
proposed rule, definitions, compliance deadlines, and EPA's statutory 
authority to regulate CCRMU. Most commenters also requested that EPA 
adopt additional requirements to address the risks from CCR units. 
EPA's responses to the comments on the proposed rule are addressed 
either in this preamble or in a response to comment document available 
in the docket to this final rule.
    EPA conducted two public hearings on the proposed rule. EPA held an 
in-person public hearing in Chicago, Illinois on June 28, 2023. At this 
hearing there were 87 speakers and a total of 150 registered attendees. 
EPA also held a virtual public hearing on July 12, 2023, using an 
internet-based software platform. The platform allowed the public 
hearing participants to provide oral testimony using a microphone and 
speakers connected to their computers or using a phone. It provided the 
ability for any person to listen to the public hearing via their 
computer. At the virtual hearing, there were 93 speakers and a total of 
353 registered attendees. Testimony at both public hearings focused 
generally on EPA's proposed amendments, and on the following topics: 
whether to further expand regulation to all CCR, regardless if it was 
onsite of a regulated facility; whether to regulate structural fill and 
other beneficial uses; enforcement of the CCR regulations; requests for 
more engagement with communities; and requests for EPA to amend other 
regulations to strengthen corrective action and limit the use of 
alternative source demonstrations (ASD). Finally, some commenters 
discussed site-specific concerns of facilities near their homes, or 
health effects witnessed in communities close to CCR sites, and general 
concerns about the health and environmental risks from CCR.

[[Page 38956]]

Transcripts for both public hearings are included in the docket for 
this action.

F. 2023 Notice of Data Availability

    On November 14, 2023, EPA published a notice of data availability 
(NODA), to solicit comments on additional information and statistics 
developed in response to comments on the Agency's May 18, 2023 proposed 
rule. 88 FR 77941. Some of the information contains data or analysis 
obtained directly from comments submitted during the May 18, 2023 
proposed rule's comment period, which might aid in the formulation of 
the final rule. EPA also solicited comments on a supplemental risk 
assessment EPA conducted in response to comments raised on the proposed 
rule. This risk assessment builds on the findings of the previous Human 
and Ecological Risk Assessment of Coal Combustion Residuals (2014 Risk 
Assessment) \4\ and better quantifies the specific risks that may 
result from placement of CCR in legacy CCR surface impoundments and 
CCRMU. EPA requested comment on all aspects of the assessment including 
the validity and propriety of relying on the new information, data, and 
analyses contained in the updated risk assessment to inform the final 
rule.
---------------------------------------------------------------------------

    \4\ U.S. EPA. 2014. ``Human and Ecological Risk Assessment of 
Coal Combustion Residuals.'' RIN 2050-AE81. Office of Solid Waste 
and Emergency Response. Washington, DC. December.
---------------------------------------------------------------------------

    EPA also sought further information on legacy CCR surface 
impoundments and CCRMU, including information on the location, 
presence, condition, history, and risk associated with any of the 
potential legacy CCR surface impoundments or any of the potential CCRMU 
within the docket. EPA also requested any information regarding the 
presence of water, distance to surface water bodies, proximity to 
floodplains, unit size, CCR volume, depth to groundwater, date of CCR 
placement, closure status, any corrective action associated with the 
unit, and any groundwater monitoring data. EPA also requested comment 
on the accuracy of the information that was submitted regarding 
potential legacy CCR surface impoundments or potential CCRMU. 
Furthermore, EPA sought similar information on any other potential 
legacy CCR surface impoundments or potential CCRMU of which EPA may not 
be aware or for which we may have incomplete information.
    EPA accepted public comment on the NODA until December 11, 2023. 
The Agency received over 70 comments on the NODA. Commenters included 
individual electric utilities and independent power producers, national 
trade associations, State agencies, public interest and environmental 
groups, private citizens, and entities involved with the beneficial use 
of CCR. All public comments submitted in response to the NODA can be 
found in the docket for this action. The majority of commenters focused 
on the supplemental risk assessment; some focused on the request for 
additional information on the universe of legacy CCR surface 
impoundments and CCRMU. EPA's responses to comments received on the 
NODA are addressed either in an updated risk assessment (the 2024 Risk 
Assessment), this preamble, or in the response to comment document 
available in the docket to this final rule.

III. What final action is the Agency taking?

    In response to the USWAG decision, EPA is finalizing a provision at 
Sec.  257.50(e), specifying that legacy CCR surface impoundments are 
subject to 40 CFR part 257, subpart D. EPA is also requiring owners or 
operators of legacy CCR surface impoundments to comply with the 
following existing requirements in the CCR regulations: installation of 
a permanent marker, history of construction, hazard potential 
classification, structural stability and factors of safety assessments, 
emergency action plan (EAP), air criteria, inspections, groundwater 
monitoring and corrective action, closure and post-closure care, 
recordkeeping, and notification and CCR website requirements. EPA 
further is establishing new compliance deadlines for these newly 
applicable regulatory requirements to ensure the owners or operators of 
these units have time to come into compliance.
    In addition to the revisions EPA proposed to address the USWAG 
decision, EPA is establishing requirements to address the risks from 
currently exempt solid waste management that involves the direct 
placement of CCR on the land. EPA is extending a subset of the existing 
requirements in 40 CFR part 257, subpart D to CCRMU, which are CCR 
surface impoundments and landfills that closed prior to the effective 
date of the 2015 CCR Rule, inactive CCR landfills, and other areas 
where CCR is managed directly on the land. These additional 
requirements apply to all active CCR facilities, all inactive 
facilities with legacy CCR surface impoundments subject to this final 
rule, and those active facilities (i.e., facilities producing 
electricity for the grid as of October 19, 2015) that ceased placing 
CCR in onsite CCR units prior to the effective date of the 2015 CCR 
Rule.
    EPA is also finalizing alternative closure provisions to allow a 
facility to complete the closure by removal in two stages: first, by 
completing all removal and decontamination procedures; and second, by 
completing all groundwater remediation in a separate post closure care 
period.
    Lastly, EPA is finalizing several technical corrections to the CCR 
regulations. These are: (1) to clarify the definitions of ``feasible'' 
and ``technically feasible''; (2) to correct the CFR reference in the 
definition of wetlands at Sec.  257.61(a); (3) to correct a reference 
in the groundwater monitoring scope section; (4) to standardize the 
references to CCR websites throughout the CCR regulations; and (5) to 
extend the period for document retention and posting.

A. Risks From Legacy CCR Surface Impoundments and CCR Management Units

1. Summary of May 2023 Proposal
    The proposal largely relied on the model results from the 2014 Risk 
Assessment, as EPA considered the results were equally applicable to 
legacy CCR surface impoundments and CCRMU.\5\ This determination was 
based on the fact that many of these unregulated units are similarly 
constructed, manage the same types of ash, and are frequently located 
either at the same or nearby facilities as their regulated 
counterparts. In particular, some unregulated units are known to be 
located directly adjacent to or beneath currently regulated units.
---------------------------------------------------------------------------

    \5\ U.S. EPA. 2014. ``Human and Ecological Risk Assessment of 
Coal Combustion Residuals.'' RIN 2050-AE81. Office of Solid Waste 
and Emergency Response. Washington, DC. December.
---------------------------------------------------------------------------

    The 2014 Risk Assessment concluded that the management practices 
that EPA believed were generally in use in 2014 at surface impoundments 
and landfills were likely to pose risks to human health through 
groundwater exposure within the range that EPA typically considers 
warrants regulation. For highly exposed individuals, the cancer risks 
from arsenic due to the operation of surface impoundments were as high 
as 2 x 10-\4\, while noncancer risks were as high as an HQ 
of 5 for arsenic, 2 for lithium, and 2 for molybdenum. Cancer risks 
associated with the operation of landfills were estimated to be as high 
as 5 x 10-\6\ from the ingestion of arsenic-contaminated 
drinking water. In 2015, EPA relied on this risk assessment to support 
the regulation of both active CCR units and inactive CCR surface

[[Page 38957]]

impoundments at active facilities. The 2014 Risk Assessment reported 
risks for the units that were anticipated to be subject to the 2015 CCR 
Rule and therefore drew no conclusions about the older units excluded 
from the scope of that rule. Nevertheless, information available in the 
record supports the conclusion that these older units can pose risks at 
least as high as reported in the 2014 Risk Assessment.
    EPA further proposed to find that the risks associated with legacy 
impoundments and CCRMU may be even higher than EPA modeled on a 
national scale in the 2014 Risk Assessment for active units. First, the 
proposal explained that these units have been present onsite for longer 
and had more time to leak. In addition, EPA explained that there are 
several management practices that have the potential to result in 
higher leakage, but that were previously modeled either less frequently 
for active units--based on a belief that the practices had declined 
over time--or not at all--due to data constraints on a national scale. 
These include: (1) The greater prevalence of unlined units; (2) The 
greater likelihood of co-management of CCR with coal refuse and other 
wastes in surface impoundments, making the overall waste pH far more 
acidic and (3) The potential for the units to be constructed below the 
water table or to have become inundated with groundwater after 
construction. The proposal estimated that the solid waste management 
practices associated with legacy impoundments and CCRMU could pose 
lifetime cancer risks from arsenic as high as 2 x 10-\5\ to 
1 x 10-\3\ (i.e., 2 to 100 cases of cancer for every 100,000 
individuals exposed), and non-cancer risks for cobalt as high as an HQ 
of 13, mercury up to an HQ of 13, lithium up to an HQ of 3, molybdenum 
up to an HQ of 4, and thallium up to an HQ of 2, depending on the 
specific management practice. Finally, EPA explained that each of these 
practices individually can pose greater risks than those previously 
modeled for the currently regulated universe of CCR units, and a 
combination of these practices could push risks even higher.
2. 2023 Draft Risk Assessment
    A number of commenters claimed that the 2014 Risk Assessment did 
not adequately capture various factors associated with legacy CCR 
surface impoundments and CCRMU that the commenters believed will result 
in significantly different risks than those posed by currently 
regulated units. In response to these comments, EPA conducted a 
supplemental risk assessment to determine the potential for some of 
these factors to affect national risks. This risk assessment built on 
the findings of the 2014 Risk Assessment and better quantified the 
specific risks that may result from placement of CCR in legacy CCR 
surface impoundments and CCRMU.
    The 2023 draft supplemental assessment consisted of: (1) Additional 
modeling of inactive and closed CCR landfills and surface impoundments 
that was actually conducted in 2014 using the same methodology and 
data. These results were ultimately not included in the original 2014 
Risk Assessment because the units were not regulated under the final 
2015 rule, and (2) Some further model runs relying on some updated 
data. In addition, EPA modeled the placement of CCR in smaller 
quantities than would typically be found in a CCR surface impoundments 
or landfill (i.e., smaller CCRMU placements or CCRMU fills) to 
determine the potential for these smaller CCRMU placements to 
contaminate groundwater. Through this modeling, EPA identified 
potential for these fills to contaminate onsite groundwater. Model 
results indicated potential for exceedance of groundwater protection 
standards (GWPS) at the fill boundary under both high-end and moderate 
conditions. These results also showed potential for substantial spread 
of the resulting groundwater plume. Under high-end conditions, these 
plumes are large and persistent enough to sustain exposures for over a 
century or more at average risks of 2 x 10-5 or higher.
    Finally, EPA assessed the potential for exposure to radiation from 
CCR remaining in the soil (subsurface). EPA found the amount of radon 
emitted by CCR is not distinguishable from background soil and so did 
not retain this pathway for further consideration. EPA also found 
greater potential for risk from gamma radiation as CCR comes to be 
located closer to the ground surface due to a reduction in shielding. 
An additional sensitivity analysis identified potential for further 
risk if CCR becomes mixed with surface soil. Accumulation of CCR can 
result in elevated cancer risk from incidental ingestion of arsenic and 
radium, in addition to direct exposure to gamma radiation from radium. 
For high-end waste concentrations, an eight percent mixture of CCR in 
surface soil was found to result in risk on the order of 1 x 
10-4.
    The 2023 draft risk assessment was made available for public 
comment as part of a NODA released on November 14, 2023.
3. Response to Comments on the Proposal and the NODA
    The following subsection provides a summary of comments received on 
either the proposed rule or NODA that are germane to the risk record 
for legacy impoundments and CCRMU. EPA considered these comments as it 
worked to finalize the supplemental risk assessment (``2024 Risk 
Assessment''). The Agency also received a number of general comments, 
which were either editorial in nature or expressed general support or 
disapproval for the risk assessment methodology, data, or results. 
However, these comments did not provide any specific technical 
recommendations or data that could otherwise be used to update the risk 
assessment. These general comments did not provide EPA with a basis to 
alter or otherwise re-evaluate the risk assessment in response.
a. Comments Related to Applicability of 2014 Risk Assessment
    Comment: Several commenters generally affirmed the Agency's risk 
basis for regulating historical and inactive disposal units. However, 
other commenters argued the Agency's risk record is inadequate to 
support regulation of certain legacy impoundments or any CCRMU. Others 
contended that because the 2014 Risk Assessment supported regulation of 
active landfills and surface impoundments, it is not appropriate to 
apply that record to disposal units that previously ceased receipt of 
waste. In particular, commenters pointed to the current lack of ponded 
water and/or the presence of a cap and vegetative cover that would 
reduce infiltration through certain units. Some commenters noted that 
State programs may include requirements for unit design, monitoring, 
and closure that ensure a cover is present. Commenters stated these 
factors must be accounted for through an updated risk assessment.
    EPA Response: Claims that the results of the 2014 Risk Assessment 
are applicable only to active units represent a fundamental 
misunderstanding of scope of the 2014 Risk Assessment. EPA did not only 
model units during operation. Instead, the risk assessment modeled the 
specific stage of the unit lifecycle anticipated to contribute the most 
to long-term risk. For surface impoundments this was during operation, 
but for landfills it was after closure. EPA modeled the leakage that 
occurred over this one lifecycle stage and tracked the subsequent 
migration through groundwater over time. The risks to downgradient 
receptors

[[Page 38958]]

resulting from the modeled leakage were used to represent risk over the 
entire unit lifecycle. Consideration of a single lifecycle stage was 
necessary because of model constraints and the high computational 
burden of tracking shifting configurations for every single unit.
    Both landfills and surface impoundments progress through similar 
lifecycle stages from construction to closure. Thus, the fact that some 
historical and inactive units may no longer contain ponded water or may 
have installed a soil cover only places these units in a different 
stage of that lifecycle. That does not differentiate the long-term 
risks of those units from those previously modeled. In particular, 
existing groundwater contamination does not vanish once a unit ceases 
operation. As one State commenter noted, ``[g]roundwater contamination 
is an important aspect to legacy impoundment closure and should not be 
overlooked simply because the impoundment does not contain liquid or 
CCR at the date of the final rule.''
    By contrast, the 2014 Risk Assessment only modeled landfills after 
closure; in other words, EPA assumed that no leakage occurred prior to 
closure, while the landfill was operating. EPA only modeled landfills 
after closure because based on the assumption that this stage of the 
landfill lifecycle would have the greatest contribution to long-term 
risk for offsite receptors because the unit would be filled to capacity 
and the post closure stage represented the greater period of time over 
which leakage can occur. EPA modeled unlined units with a soil cap and 
vegetative cover equivalent to the surrounding native soils and found 
risks from arsenic as high as 2 x 10-5 for receptors up to a 
mile away. Even assuming some landfills have been closed in a manner 
more consistent with the existing CCR regulations (i.e., with some kind 
of composite cover system), this is unlikely to change the overall 
conclusions of the risk assessment. This is because, regardless of the 
cover that is ultimately installed, higher leakage can occur throughout 
the active life of the unit when the landfill face is open and able to 
intercept more precipitation. This conclusion is reinforced by the fact 
that facility monitoring reports document that around 20% of currently 
active landfills have triggered corrective action. Additionally, EPA 
has seen no evidence to suggest that the closure of older units has 
been consistently more protective than EPA modeled in 2014. As 
discussed in Unit III.B.2.g.iii(a) of the preamble, as part of 
developing the 2015 CCR Rule, EPA reviewed State statutes and 
regulations, with a more detailed focus on the 16 States responsible 
for approximately 74% of the CCR generated in 2009. See 80 FR 21324. 
The Agency's review of State programs prior to 2015 found that 
oversight of these wastes and the overall protectiveness of particular 
programs varied widely. For example, EPA estimated that in 2015, 
approximately 20% of the net disposable CCR was entirely exempt from 
State regulatory oversight. Similarly, a 2006 joint Department of 
Energy (DOE) and EPA study reported that only 19% (three out of 19) of 
the surveyed surface impoundment permits included requirements 
addressing GWPS (i.e., contaminant concentrations that cannot be 
exceeded) or closure/post-closure care. Furthermore, some of the 
photographs and descriptions of these older units provided by 
commenters indicate extensive growth of trees and other woody 
vegetation that can compromise the integrity of any cap present and 
increase the rate of infiltration into the unit. For these reasons, the 
2014 Risk Assessment is equally representative of the national risks 
from historical and inactive landfills.
    The 2014 Risk Assessment modeled all surface impoundments during 
the active stage of their lifecycle. This was based on the presumption 
that the highest rates of leakage would occur while wastewater is 
ponded above the ash, because this water creates a large and sustained 
hydraulic head that serves to drive leachate into the subsurface. 
Although the current configuration of historical and legacy 
impoundments may vary, all these units previously held ponded water 
during the active stage of their lifecycle. And, in the case of legacy 
impoundments, ponded water may still be present. As a result, the 
current configuration of the unit is immaterial to the releases that 
occurred during operation. For this reason, the modeling approach 
relied upon in the 2014 Risk Assessment is equally applicable to 
historical and legacy impoundments.
    The 2014 Risk Assessment also accurately represents the potential 
risks that remains for units that were closed consistent with the 2015 
CCR Rule. If the cover system is not adequately maintained after 
closure, degradation over time from human or animal activity, natural 
settling, freeze-thaw cycles, flooding and other extreme weather 
events, and other factors can result in greater leakage from the unit 
than designed. In some cases, groundwater monitoring may provide the 
only clear evidence the cap is not performing as designed. Thus, the 
2014 Risk Assessment accurately describes the risks that can result if 
these units are not adequately maintained and monitored in line with 
regulatory requirements.
    Comment: Multiple commenters argued that historical and inactive 
disposal units will generally have a smaller footprint than those 
modeled in the 2014 Risk Assessment. For example, some commenters noted 
the average sizes of landfills and surface impoundments modeled in the 
2014 Risk Assessment were around 120 acres and 50 acres, respectively, 
while the estimated average sizes of CCRMU and legacy impoundments in 
the proposed rule were both closer to 30 acres. Others cited to the 
sizes of individual units that at their facilities to contend that 
these units are much smaller than average. These commenters contended 
that a smaller footprint would result in a lower mass loading of 
groundwater and lower associated risk.
    EPA Response: EPA disagrees that the referenced data indicate that 
older disposal units are significantly smaller in size than the units 
EPA modeled in 2014. The 2014 Risk Assessment relied on data submitted 
by facilities in the EPA Surveys to estimate an average active landfill 
size of around 120 acres from over 310 landfills and an average active 
impoundment size of around 50 acres from over 735 impoundments. The RIA 
summary referenced by commenters relies only on data that could be 
independently verified by data from posted facility reports and recent 
public comments. From the final list of 195 CCRMU and 194 legacy 
impoundments, EPA identified data for only one landfill with a size of 
90 acres and 47 historical or legacy impoundments with an average size 
of 44 acres. Thus, when CCRMU are separately grouped as landfills and 
impoundments, the differences in size are not as substantial as 
indicated by commenters.
    EPA also disagrees that any differences that do exist would result 
in substantially lower risks than previously modeled. As part of the 
2014 Risk Assessment, EPA modeled 122 landfills and 163 impoundments 
that were excluded from the reported risk results because these units 
were determined to not be subject to that rule. These excluded units 
represent some combination of legacy impoundments, inactive landfills, 
and historical disposal units. The average sizes of these previously 
excluded units are 77 acres for the landfills and 28 acres for the 
impoundments. These sizes are approximately half the size of the units

[[Page 38959]]

identified in the 2014 Risk Assessment or more recent data collection 
efforts. However, as discussed in Section 3 of the 2024 Risk 
Assessment, the risks associated with these older units are 
substantially the same as those for currently regulated units. 
Therefore, there is no evidence that these differences in size have a 
meaningful impact on national risks, or that the results of the 2014 
Risk Assessment are nor equally applicable to legacy impoundments and 
CCRMU. While there may be individual disposal units at these sites that 
are smaller than average, the model results summarized in the 2024 Risk 
Assessment model include landfills as small as 2 acres and impoundments 
as small as 0.01 acres. Therefore, there is no indication based on the 
data provided that the overall distribution of unit sizes has not been 
adequately reflected in the national model.
    Finally, EPA notes that individual unit size is not necessarily a 
reliable metric to draw conclusions about the overall risk from CCR 
disposal at electric utilities. The 2014 Risk Assessment modeled the 
risks from each landfill and impoundment separately because it was 
difficult to confirm the relative locations and orientations of 
different units with data from the EPA Surveys. However, the Agency is 
now aware of many sites where multiple units, both landfills and 
impoundments, are located immediately adjacent to one another. As a 
result, there is potential the 2014 Risk Assessment underestimated site 
risk to some degree by not evaluating the combined leakage over the 
full contributing area of these adjacent disposal units.
    Comment: One commenter stated the 2014 Risk Assessment did not 
specifically characterize the risks from impoundments that do not 
contain fly ash. This commenter argued that historical and legacy 
impoundments are more likely to only contain bottom ash or boiler slag, 
as the process of capturing fly ash was not common prior to the 1970s. 
Therefore, this commenter concluded that the 2014 Risk Assessment does 
not adequately characterize the risks for these older units.
    EPA Response: EPA disagrees that the 2014 Risk Assessment does not 
address the risks associated with these impoundments. The risk 
assessment incorporated porewater data from impoundments that contained 
only bottom ash, but EPA did not separately break out risks for this 
subset of units because the amount of data available was inconsistent 
across the set of modeled constituents. However, available porewater 
data show the potential for certain constituents, such as molybdenum, 
to leach from bottom ash at levels as high as from fly ash.
    Additionally, available monitoring reports for currently regulated 
units posted on facility websites document that these units have a 
similar potential to contaminate groundwater as units containing other 
types of CCR. Of the units designated as managing bottom ash, 32% of 
surface impoundments and 38% of landfills have triggered corrective 
action. Of the units designated as managing slag, 38% of surface 
impoundments have triggered corrective action. No landfills were 
identified as dedicated to slag. For comparison, 48% of remaining 
surface impoundments and 21% of remaining landfills have triggered 
corrective action. Therefore, there is no indication that these types 
of units are overall less likely to result in groundwater 
contamination.
    Comment: One commenter claimed that a nationwide assessment should 
not be used to make determinations about the risks at individual sites 
or to support national requirements. This commenter stated that, unlike 
individual damage cases, the Agency's groundwater model does not 
adequately represent the specific conditions at each individual unit. 
However, this commenter provided no data to support their broad claims. 
One other commenter pointed to data they had identified to contend that 
the model does not reflect the specific environmental conditions at 
their facility.
    EPA Response: The modeling conducted for both the 2014 and 2024 
Risk Assessments utilized a probabilistic, site-based approach that 
combined site-specific data with more regional and national data 
sources. The model incorporated data about the specific location, 
dimensions, and liner status of individual disposal units where 
available. The aim of this approach is not to assign an exact risk to 
each individual unit, but to provide an overall accurate picture of the 
potential risks posed by these types of units on a national scale. 
Indeed, many of the findings from the 2014 Risk Assessment were 
supported by available damage cases. The commenters did not articulate 
why they believe the risks associated with individual units fall far 
outside the broader distribution of modeled units. But as acknowledged 
by the one commenter who did submit data, there is overlap between the 
range of conditions modeled and those they identified as present at 
their particular facility. EPA does acknowledge that there are some 
site conditions that the 2014 and 2024 Risk Assessments were not able 
to adequately model, such as waste below the water table. However, this 
is why the Agency separately relied on damage cases to identify 
additional constituents of potential concern for groundwater 
monitoring.
    Comment: One commenter stated that EPA should not rely on the 
findings of the Environmental Integrity Project's report, ``Poisonous 
Coverup: The Widespread Failure of the Power Industry to Clean Up Coal 
Ash Dumps'' without independently validating the quality of analyses 
conducted for each site.
    EPA Response: EPA recognizes that the method used in the cited 
report to identify potential exceedances of GWPS is not the same as the 
regulatory standard for triggering corrective action. For this and 
other reasons, the Agency does not rely on the report as a primary 
basis for the current rulemaking or to draw any conclusions about the 
monitoring status of any individual unit. Instead, EPA previously 
referenced the report as a supplementary source of information that 
further supports the findings of the 2014 Risk Assessment. 
Specifically, the fact that the constituents identified as risk drivers 
in the 2014 Risk Assessment are the same ones detected most frequently 
above GWPS indicates that the fate and transport modeling conducted by 
EPA was able to correctly identify the constituents most likely to be 
released and migrate at environmentally significant concentrations. 
While high background concentrations may be present at some of these 
sites, many have already triggered corrective action and the Agency 
believes that number will increase as more facilities come into 
compliance with the rule requirements. Because this report does not 
form a basis for the rule, it is not discussed further in the preamble 
to the rule or the 2024 Risk Assessment outside of responses to other 
comments that cite to the same or similar reports.
b. Comments Related to Draft 2023 Supplemental Risk Assessment 
Conceptual Model
    Comment: Multiple commenters broadly argued that the draft 2023 
risk assessment relied on data and assumptions that represent maximum 
values or otherwise reflect worst-case scenarios that could never 
occur, and therefore do not represent a ``reasonable probability'' of 
adverse impacts and so is not an appropriate basis for regulatory 
action.
    EPA Response: EPA disagrees that the design of the risk assessment 
is inappropriately conservative. Consistent

[[Page 38960]]

with EPA's long-standing practice under RCRA (as well as other agency 
programs), an individual with reasonable maximum exposure (RME) 
provides the principal basis for evaluating potential human health 
risks. An RME scenario is intended to be conservative, while remaining 
within the range of possible high-end exposures.\6\ Specifically, 
``high end'' has been defined as the part of the exposure distribution 
that falls above the 90th percentile, but below the 99.9th 
percentile.\7\ Reliance on this type of scenario is intended to protect 
sensitive populations. Selection of the data and assumptions 
incorporated in the 2024 Risk Assessment is in line with this 
objective. Further critiques about the potential for the specific data 
and assumptions to overestimate risk are addressed in subsequent 
responses.
---------------------------------------------------------------------------

    \6\ U.S. EPA. 1989. ``Risk Assessment Guidance for Superfund 
Volume I--Part A, Human Health Evaluation Manual.'' EPA/540/1-89/
002. Prepared by the Office of Emergency and Remedial Response, 
Washington, DC. December.
    \7\ U.S. EPA. 2004. ``An Examination of EPA Risk Assessment 
Principles and Practices.'' EPA/100/B-04/00. Prepared by the Office 
of the Science Advisor. Washington, DC. March.
---------------------------------------------------------------------------

    Comment: Multiple commenters argued that it was inappropriate for 
EPA to consider future onsite residential exposures as a basis for 
evaluating the potential risks associated with onsite CCR disposal. One 
commenter claimed that the estimates of existing populations living 
near these facilities used in the 2024 Risk Assessment was both 
overestimated and inconsistent with estimates from the Agency's RIA. 
One commenter acknowledged that older units tend to be located closer 
to population centers. However, others argued that this proximity to 
existing populations or water bodies would not make them overall more 
likely to become residential in the future. One commenter stated that 
EPA should have surveyed the intended land use for facilities or 
otherwise directly assessed the likelihood of residential land use.
    EPA Response: EPA disagrees that consideration of a population 
within a five-mile radius overstates the likelihood of residential 
development. Five miles away from a population center is a small 
distance for residential development to expand, even in the near 
future. Nevertheless, the Agency has updated the population estimates 
in the 2024 Risk Assessment to more closely align with reporting in the 
RIA and to include both one- and three-mile radii. EPA also disagrees 
that consideration of a future residential land use scenario is 
inappropriate or unrealistic. The substantial populations already 
living near many facilities and the generally higher property value of 
land near water bodies are two indicators of the potential for land to 
be attractive for future residential land use. Facilities do not 
dictate the ultimate use of a property after the land has been sold for 
redevelopment. These types of facilities can include considerable 
tracts of land beyond that dedicated to waste disposal that may be 
considered for a range of different uses. EPA is currently aware of 22 
examples in which former electric utilities have been proposed for 
residential development, 19 of which are known to have burned coal.\8\ 
Thus, there is evidence of community interest in residential land use 
at these types of facilities.
---------------------------------------------------------------------------

    \8\ Memorandum to the Docket: Compilation of News Articles on 
Future Land Uses for Electric Utilities.
---------------------------------------------------------------------------

    Although future residential use is considered as the RME scenario 
in the 2024 Risk Assessment, that does not mean it is the only scenario 
EPA considered or on which this final rule is based. Depending on their 
location, leakage of Appendix IV constituents from individual CCRMU 
fill may migrate off-site at levels of concern. In addition, even if 
the constituents from a single CCRMU do not migrate off-site, the 
modeling conducted in 2024 confirms that smaller CCRMU fills can 
meaningfully contribute to groundwater contamination across a facility. 
Concentrations from a single CCRMU can combine with contamination from 
other CCRMU, currently regulated CCR units, or legacy CCR surface 
impoundments that are also present on the same site. Although EPA did 
not model the aggregate or cumulative risk associated with these 
potential sources of co-located contamination, at a minimum, EPA 
expects that the presence of multiple sources of potential 
contamination at the same facility would increase the likelihood of a 
contaminant plume that could migrate off-site at levels of concern.
    Nor is residential use the only scenario where exposures present 
concern. One commenter described donating property to a local 
government for recreational uses. Several other commenters described 
redeveloping sites as nature preserves. Even under these non-
residential land uses, the is a reasonable potential for exposure (and 
consequently risk) to human and ecological receptors if the ash is 
subsequently disturbed. For example, as discussed in Section 6 the 2024 
Risk Assessment, concentrations of certain contaminants may also pose 
risk to wildlife if ash becomes intermingled with surface soil.
    Comment: Commenters asserted that consideration of residential land 
use is inconsistent with various EPA guidance documents 
9 10 11 and Agency cleanup programs. These commenters argued 
such guidance instructs EPA to assume that facilities surrounded by 
operating industrial facilities will remain industrial unless there is 
clear evidence otherwise. These commenters further argued that guidance 
instructs EPA to account for institutional controls, such as State or 
local zoning laws, that would make residential development or resulting 
exposures at individual sites unlikely. Some commenters cited to 
specific State requirements they assert would prevent residential land 
use or prohibit future use of site groundwater as a source of drinking 
water. Others claimed that due diligence reviews would be adequate to 
identify and address any remaining sources of contamination before 
exposures could occur.
---------------------------------------------------------------------------

    \9\ U.S. EPA. 1989. ``Risk Assessment Guidance for Superfund 
Volume I Human Health Evaluation Manual (Part A).'' EPA/540/1-89/
002. Prepared by the Office of Emergency and Remedial Response, 
Washington, DC. December.
    \10\ U.S. EPA. 1991. ``Risk Assessment Guidance for Superfund 
Volume I Human Health Evaluation Manual (Part B, Development of 
Risk-based Preliminary Remediation Goals).'' Publication 9285.7-01B. 
Prepared by the Office of Emergency and Remedial Response, 
Washington, DC. December.
    \11\ U.S. EPA. 1995. ``Land Use in the CERCLA Remedy Selection 
Process.'' OSWER Directive No. 9355.7-04. Prepared by the Office of 
Solid Waste and Emergency Response. Washington, DC. May.
---------------------------------------------------------------------------

    EPA Response: EPA disagrees that consideration of future 
residential land use at these facilities is inconsistent with 
applicable guidance and cleanup programs. First, the risk assessment 
was conducted to establish minimum national criteria rather than to 
clean up an individual site. To determine whether the section 4004(a) 
standard will be met at all sites nationwide, as the statute requires, 
the Agency needs to evaluate the risks associated with full range of 
reasonable scenarios. As discussed in the previous response, there are 
numerous examples in the record of instances in which these kinds of 
sites have been redeveloped for residential use.
    Moreover, as the commenters have acknowledged, the Comprehensive 
Environmental Response, Compensation, and Liability Act (CERCLA) and 
other cleanup programs only address contamination that has already 
occurred. In contrast, national standards for waste management 
developed under RCRA section 4004(a) are to prevent environmental 
releases

[[Page 38961]]

before they occur. See, USWAG, 901 F.3d at 429-431. As EPA has 
previously explained, groundwater contamination is a concern, even if 
the aquifer is not currently used as a source of drinking water. 
Sources of drinking water are finite, and future users' interests must 
also be protected. See, 44 FR 53445-53448.
    EPA further disagrees that the risk assessment failed to 
appropriately account for existing State and local requirements for 
institutional controls that would limit residential exposure. The 
purpose of a baseline risk assessment is to provide ``. . . an analysis 
of the potential adverse health effects (current or future) caused by 
hazardous substance releases from a site in the absence of any actions 
to control or mitigate these releases (i.e., under an assumption of no 
action).'' \12\ Thus, the intent of the risk assessment is to 
characterize the harm that could result if institutional and other 
controls are not implemented. This provides a consistent basis to 
understand the risks to be controlled and define appropriate national 
requirements such as a national requirement for deed restrictions at 
all sites at which CCRMU fills will remain in place. The Agency did not 
assume that all facilities will ultimately be used for residential 
purposes as a consequence of these factors in developing this final 
rule.
---------------------------------------------------------------------------

    \12\ U.S. EPA. 1989. ``Risk Assessment Guidance for Superfund 
Volume I Human Health Evaluation Manual (Part A).'' EPA/540/1-89/
002. Prepared by the Office of Emergency and Remedial Response, 
Washington, DC. December.
---------------------------------------------------------------------------

    Furthermore, as several commenters have acknowledged, facilities 
have not historically been required to identify smaller placements of 
ash as a form of disposal and consequently have not maintained reliable 
records of where such placements are located. Indeed, most commenters 
have acknowledged that they are currently unable to identify all CCRMU 
at their existing facilities. These commenters do not explain how due 
diligence assessments would reliably identify such placements in the 
absence of such records, as such assessments typically rely on 
available site records to guide further investigation. Nor do 
commenters explain how existing State programs would reliably identify 
such placements or otherwise prevent exposures, when the facilities 
themselves cannot identify the presence of the ash on-site. This is 
reinforced by EPA's review of State programs, which found that the 
specific requirements, level of oversight over these wastes, and the 
overall protectiveness of individual programs varied widely among 
States. See, 80 FR 21324. As a result, EPA currently lacks a record to 
conclude that currently unidentified CCRMU fills located across a 
facility would be subject to the same institutional controls that are 
required for the disposal units the commenters reference. Given the 
current absence of national requirements, and that commenters have 
generally acknowledged that they have not reliably kept records of the 
existence of CCRMU, it is appropriate to evaluate the risks that can 
reasonably arise in the absence of institutional controls.
    Comment: One commenter argued that EPA had already considered the 
practice of disposal below the water table because it had been 
discussed in previous risk assessments. Another commenter asserted the 
Agency's conceptual model assumed all legacy impoundments were in 
contact with the water table. Another commenter stated that EPA cannot 
use information about active units to make assumptions about which 
historical and inactive units at the same sites are in contact with the 
water table, due to differences in unit construction and location. By 
contrast, a number of other commenters agreed that because EPA cannot 
model the effects of waste below the water table, EPA had previously 
underestimated the risks associated with CCR units. Other commenters 
argued the conceptual model for surface impoundments did not adequately 
distinguish between the types of water that may be present in an 
impoundment. These commenters asserted that any residual water 
remaining after the unit has been initially drained would not exert the 
same hydraulic head within the unit that would drive leachate into the 
subsurface during unit operation, and so leakage would more closely 
resemble a landfill.
    EPA Response: The conceptual models for landfills and surface 
impoundments in the 2014 and 2024 Risk Assessments did not evaluate 
contact with groundwater. Although these assessments both acknowledged 
that this could occur, the scenario could not be incorporated into 
groundwater fate and transport modeling as a result of data and model 
constraints. Because the 2014 and 2024 Risk Assessments did not 
directly model the effects of disposal below the water table, neither 
assessment incorporates any assumptions about the prevalence of this 
practice in the conceptual model. EPA has acknowledged that its 
inability to reliably model the effects of this practice means that its 
risk estimates on a national scale underestimate the risks associated 
with higher rates of leaching and/or formation of strongly reducing 
conditions.
    EPA acknowledges the rates of leakage from surface impoundments 
will generally decrease after ponded wastewater has been allowed to 
drain, reducing the overall hydraulic head across the unit. As such, 
discussion in the 2024 Risk Assessment has been updated to clarify the 
distinction between water ponded above the ash and porewater within an 
impoundment. However, any free liquids that remain within the unit can 
still result in higher leakage than would occur if the unit were fully 
dewatered. And the amount of ``residual water remaining'' can sometimes 
be substantial; in some cases, closed impoundments remain saturated by 
20-54 feet of groundwater. See, e.g., 88 FR 31982-319873, 55236.
    In addition, regardless of the current configuration of an 
impoundment, it is appropriate for the conceptual models in the 2024 
Risk Assessment to consider the stage of the unit lifecycle anticipated 
to contribute the most to long-term risk. For surface impoundments, 
this is when the units are in operation due to the presence of 
wastewater ponded above the ash. Subsequent draining of the unit does 
nothing to remediate any adverse impacts that occurred during 
operation. Furthermore, to the extent that impoundments leak at rates 
more similar to landfills after ponded wastewater has been drained, EPA 
notes the 2014 Risk Assessment previously modeled the risks from dry 
management in landfills and found the potential for unacceptable risk 
from these units. Therefore, continued leakage from drained units still 
has the potential to sustain releases.
    Comment: One commenter affirmed that ``EPA is likely correct in its 
observations and assumptions that CCRMU fills `will remain in place 
when ownership of the property changes,' and that, `in the absence of 
land use restrictions, there is no guarantee [that] engineering 
controls will remain in place when the property is redeveloped.' '' 
However, multiple commenters argued the conceptual model for CCRMU 
fills does not adequately account for the full diversity of CCRMU that 
may be present onsite. Various commenters stated that a conceptual 
model for fills does not adequately address specific types of 
placements, such as use in the construction or closure of CCR disposal 
units, storage in waste piles, construction of roadways and railroads, 
or spreading on roadways for snow and ice control. Another asserted 
that reliance on the similar conceptual models in the 2014 Risk 
Assessment to

[[Page 38962]]

evaluate the disposal units and CCRMU fills is inappropriate because 
the CCRMU fills will tend to be smaller than the disposal units modeled 
in 2014.
    EPA Response: EPA disagrees that the conceptual model for CCRMU 
fills does not adequately address the configurations of these units. 
The majority of the units described by commenters have a concentrated 
footprint, such as placement beneath a parking lot. Some of the 
specific alternate examples raised by commenters are either already 
regulated under the existing regulations (e.g., waste piles) or are 
outside the scope of the current rulemaking. For others, there is 
little to no information available about the manner or frequency of 
such placements that could be used to characterize the units. 
Therefore, these types of placements are not considered as part of the 
conceptual model for CCRMU fills in the 2024 Risk Assessment.
    The commenters do not explain how placement of CCR in a landfill or 
impoundment in service of construction or closure of that unit would be 
substantially different than the disposal scenarios previously modeled 
and found to pose risk. Finally, EPA has proposed and is finalizing the 
definition of CCRMU to exclude CCR used in roadbed and associated 
embankments.
    There is little data that could be used to develop a conceptual 
model for diffuse placements, which may occur on a periodic basis. Nor 
do commenters provide any data on the manner or frequency of such 
placements. As a result, the 2024 Risk Assessment did not model these 
types of placements. This represents a source of uncertainty in the 
assessment. However, EPA notes that even small placements of CCR can 
contribute to broader leakage and have the potential to leak Appendix 
III constituents and influence nearby groundwater monitoring. 
Therefore, it is still necessary to identify where these types of 
onsite placements have occurred.
    EPA also disagrees that applying a similar conceptual model for CCR 
landfills and CCRMU fills is inappropriate. Specifically, the 
conceptual model does not make any upfront assumptions regarding the 
sizes of these fills. As described in Section 4 of the 2024 Risk 
Assessment, EPA considered a range of potential sizes for these fills 
that were smaller than landfills reported in the EPA Surveys.
    Comment: One commenter stated that it is inappropriate for the 2024 
Risk Assessment to rely on similar data sources as the 2014 Risk 
Assessment to characterize environmental parameters, claiming these 
data are outdated. Another argued that the conceptual model does not 
adequately account for the presence of alternative liners, such as 
thick natural clay beneath the units.
    EPA Response: First, EPA notes that the 2024 Risk Assessment does 
incorporate more recent weather data available from the most recent 
version of the Hydrologic Evaluation of Landfill Performance Model, 
updated in 2020. As explained in the 2014 Risk Assessment, EPA found 
the remaining data sources provide the most recent and representative 
data to characterize environmental conditions on a national basis. 
Commenters provide no explanation why these data should be considered 
outdated. For example, why the soil type present at a site would have 
changed substantially since 2014. EPA notes that to the extent that 
there is natural clay soil present in the vicinity of a facility, that 
would already be reflected through the environmental data.
c. Comments Related to Supplemental Risk Assessment Groundwater Model
    Comment: Some commenters asserted that modeled leachate 
concentrations are unrealistically high. One commenter specifically 
argued that the LEAF data is unable to accurately reflect field 
leaching concentrations, citing two EPRI reports comparing LEAF and 
field leachate data both collected from the same units.13 14 
They separately compared the leachate concentrations modeled in the 
risk assessment to field samples collected from around a number of 
different landfills. Based on this comparison, the commenter asserted 
that the high-end concentrations modeled in the risk assessment were 
substantially higher than measured in the field and so unrepresentative 
of actual leaching behavior. For these reasons, this commenter 
concluded that porewater data provide better representation of leaching 
in the field and so EPA should rely on that type of data to model 
leakage from CCRMU fills.
---------------------------------------------------------------------------

    \13\ EPRI. 2020. ``Leaching, Geotechnical, and Hydrologic 
Characterization of Coal Combustion Products from a Closed Coal Ash 
Impoundment.'' Palo Alto, CA. June.
    \14\ EPRI. 2021. ``Leaching, Geotechnical, and Hydrologic 
Characterization of Coal Combustion Products from an Active Coal Ash 
Management Unit.'' Palo Alto, CA. February.
---------------------------------------------------------------------------

    EPA Reponse: EPA disagrees that leachate concentrations modeled in 
the 2024 Risk Assessment are unrealistically high. EPA has previously 
demonstrated that the LEAF laboratory leaching tests are ``effective 
for estimating the field leaching behavior for a wide range of 
materials under both disposal and use conditions.'' \15\ The two 
studies cited by commenters do not contradict these findings. Indeed, 
one of the cited reports concludes that LEAF Method 1313 measurements 
tended to only underestimate porewater concentrations of lithium and 
molybdenum and did not consistently overestimate or underestimate 
porewater concentrations of arsenic and thallium. These conclusions are 
consistent with previous Agency findings that LEAF Method 1313 
measurements (1) can underestimate leakage of highly soluble 
constituents, such as lithium and molybdenum, if not adjusted to 
properly account for the sample liquid to solid ratio and (2) can over 
or underestimate leakage of redox sensitive contaminants, such as 
arsenic, if not further adjusted with geochemical speciation modeling. 
In response to these findings, the Agency has established general 
recommendations for how to address these issues.\16\ Modeling of highly 
soluble constituents in both the 2014 and 2024 Risk Assessment are 
consistent with these recommendations. Sufficient data are not yet 
available on the prevalence or magnitude of reducing conditions to 
allow EPA to adequately model the effects of these conditions on 
leaching behavior at a national scale. However, given that the 2024 
Risk Assessment identified potential for extensive groundwater 
contamination with overall risks as high as 1 x 10-4 for the 
less mobile pentavalent speciation of arsenic, this uncertainty is 
unlikely to affect the conclusions of the risk assessment.
---------------------------------------------------------------------------

    \15\ U.S. EPA. 2014. ``Leaching Test Relationships, Laboratory-
to-Field Comparisons and Recommendations for Leaching Evaluation 
using the Leaching Environmental Assessment Framework.'' EPA 600/R-
14/061. EPA Office of Research and Development. Research Triangle 
Park, NC. October.
    \16\ U.S. EPA. 2019. ``Leaching Environmental Assessment 
Framework (LEAF) How-To Guide: Understanding the LEAF Approach and 
How and When to Use It.'' SW-846 Update VII. Prepared by the EPA 
Office of Land and Emergency Management. Washington, DC. May.
---------------------------------------------------------------------------

    EPA also disagrees that the field data presented by commenters 
demonstrates that the modeled concentrations are unrealistic. As a 
general matter, these commenters did not make available the underlying 
data for the graphs presented or the reports from which the graphs were 
drawn. Therefore, it is not possible to fully evaluate these graphs, as 
EPA cannot determine how and where these data were collected, how many 
individual samples are represented, and how the data were compiled. 
Based on

[[Page 38963]]

the limited description provided, it appears that the graphs summarize 
data on the average leachate concentrations collected from around 
different landfills. Thus, the cited median values would represent a 
median of the average measurements from each landfill. This type of 
summary does not provide a meaningful understanding of the leaching 
potential of CCR. For example, landfills can contain mixtures of 
different CCR types and other wastes, which may result in variable 
leaching profiles over the footprint of the unit. An average of 
measured leachate concentrations can mask regions of higher leaching 
potential over many acres. This potential for variable leaching is one 
reason why groundwater monitoring wells are required to be spaced along 
the entire downgradient boundary of these units. In contrast, CCRMU 
fills are smaller in size and more likely to be constructed with a 
single source of ash. Additionally, there is no indication of how long 
the waste has been present in these landfills prior to sampling. More 
soluble constituents can become depleted over time. For example, 
Modular Three-Dimension Finite-Difference Ground-Water Flow Model 
(MODFLOW) runs conducted for the 2024 Risk Assessment showed that 
molybdenum can deplete from the ash anywhere from several years to a 
few decades after leaching first began. Thus, these graphs could 
understate the full leaching potential of CCR.
    Commenters also mischaracterize the results of the probabilistic 
analysis. The 90th percentile of all model inputs for leachate 
concentration is not the same as the 90th percentile of modeled risks. 
There are a number of other model parameters that will influence 
contaminant release and subsurface transport. As a result, the model 
runs with the highest initial leachate concentrations are not always 
the same as those with the highest downgradient concentrations. EPA 
reviewed a subset of model runs around the 90th percentile risk result 
reported in the 2024 Risk Assessment, representing 1% of all model runs 
at 1,000 feet from the waste boundary. This review found the median 
leachate concentration representative of these runs was closer to 0.31 
mg/L for arsenic and 35 mg/L for molybdenum. There are multiple samples 
in the record of porewater or leaching tests with concentrations of the 
same order-of magnitude or higher than these concentrations. Therefore, 
EPA concludes that the methods used to generate model inputs do not 
result in unrealistically high leachate concentrations.
    EPA maintains that LEAF leachate provides the most realistic 
estimate of long-term leaching potential from CCR placed in fills. 
There is little field leachate data for dry-managed CCR available in 
the record, as it can be difficult to collect representative samples 
from landfills. Additionally, field samples would reflect the specific 
waste mixtures and chemistry of these disposal units. Instead, LEAF 
provides data on the leaching behavior of individual CCR under a range 
of relevant environmental conditions. EPA did consider using 
impoundment porewater data to supplement the data on leaching of 
lithium because of the lack of LEAF data for this contaminant, and 
because lithium is a highly soluble, monovalent ion expected to be less 
influenced by specific impoundment chemistry. However, this constituent 
was not modeled in the 2024 Risk Assessment due to other data 
limitations. The uncertainties associated with exclusion of lithium are 
discussed in Section 6 of the 2024 Risk Assessment.
    Comment: One commenter asserted that the distribution of leachate 
pH values used to represent CCRMU fills is unrepresentative. In 
particular, the commenter took issue with the prevalence at which 
acidic conditions were modeled within CCR fills. This commenter pointed 
to field data collected from CCR landfills to assert that leachate from 
fills would rarely be acidic.
    EPA Response: EPA disagrees that the modeled leachate pH is 
unrepresentative of conditions at smaller CCRMU fills. Modeled leachate 
pH is based on the natural pH (or ``own pH'') of the ash sample 
measured with LEAF. Thus, these data represent the properties of real 
ash samples. Landfills can contain a mixture of different CCR types and 
other related waste streams and so it is reasonable that the average pH 
of larger landfills may differ from that of individual CCR. At the same 
time, regions of individual landfills can be more acidic than average, 
which can be masked by consideration of only average values. The 
potential for such variations is part of the reason that placement of 
monitoring wells is required across the full downgradient boundary of 
these landfills. Smaller CCRMU fills are more likely to be constructed 
with a single ash type and so it is most appropriate to consider the pH 
of individual ash samples, rather than broader landfill conditions. The 
uncertainties associated with the modeling of pH are discussed in 
Section 6 of the 2024 Risk Assessment.
    Comment: One commenter stated that use of a five-mile radius to 
draw environmental data for purposes of groundwater modeling is not 
adequately justified and inconsistent with both the 2014 Risk 
Assessment and Draft 2023 RIA.
    EPA Reponse: EPA has reviewed and updated the sampling radius for 
environmental and population data. Based on this review, EPA 
established the sampling radius for environmental data at two 
kilometers (1.2 miles). This is consistent with the methodology applied 
in the 2014 Risk Assessment, which the Agency previously found 
adequately represented the environmental conditions near units for 
which a more precise location at the facility property could not be 
determined. EPA established the sampling radii for population data to 
be consistent with the rationale outlined in the 2024 RIA.
    Comment: Multiple commenters criticized the Agency's use of soil-
water partitioning coefficients (i.e., Kd values) to model contaminant 
sorption in the subsurface. These commenters argued that use of 
individual Kd values was inappropriate and unable to reflect the 
variability of subsurface transport conditions. They also stated that 
the Kd values used in the risk assessment for arsenic were biased low 
and likely to underestimate retention on soil. These commenters cited 
field measurements collected at various locations to assert that actual 
values for arsenic are likely to be higher. One commenter cited an 
alternative set of Kd values they had calculated to contend that actual 
values for arsenic would be orders-of-magnitude different than used in 
the risk assessment.
    EPA Response: These commenters are incorrect; EPA did not rely only 
on individual Kd values for the risk assessment. As part of the 2014 
Risk Assessment, EPA previously developed sorption isotherms for each 
modeled constituent, which represent the distribution of individual Kd 
values calculated and reflect the range of anticipated subsurface 
conditions and specific CCR waste characteristics. Each individual 
model run in the EPA Composite Model for Leachate Migration with 
Transformation Products (EPACMTP) samples from that distribution based 
on the key factors for that run (e.g., leachate concentration, pH, 
ionic strength). No individual model run will precisely represent 
conditions at a particular site. Instead, the model runs collectively 
capture the variability of conditions that can occur across sites. 
Thus, EPA relies on the model runs in aggregate to draw

[[Page 38964]]

conclusions about the potential for risk nationwide.
    EPA also disagrees that the specific Kd values used in MODFLOW are 
unrepresentative. The limited number of MODFLOW runs are intended to 
further characterize the subset of high-end scenarios modeled in 
EPACMTP. Thus, it is entirely reasonable that these model runs are 
those more likely to reflect scenarios where pentavalent arsenic is 
more mobile in the environment.
    The field data shared by commenters for specific CERCLA sites or 
agricultural fields are not representative of conditions at CCR 
disposal units. As previously noted, the calculated sorption isotherms 
reflect the properties of CCR leachate, which can be vastly different 
from precipitation infiltrating through soil. In particular, both the 
high ionic strength and variable pH of this leachate are expected to 
result in different sorption behavior. EPA is also unable to fully 
review the Kd values calculated by commenters or compare them with 
Agency values because the commenters provided insufficient information 
regarding whether and how specific key environmental factors were 
considered. Nevertheless, EPA notes that the range of values presented 
by commenters falls within the full distribution of Kd values developed 
for arsenic in 2014. The full distribution of values is summarized in 
Appendix H of the 2014 Risk Assessment, and is the full range of values 
EPA sampled from to model groundwater transport in the 2024 Risk 
Assessment.
    Comment: One commenter stated that any CCR material placed beneath 
the soil would become naturally compacted. Another commenter asserted 
that the pozzolanic nature of some ash would result in far lower 
hydraulic conductivity than EPA modeled.
    EPA Response: In the absence of periodic inspections and a well-
maintained cap, there is no guarantee that any ash placed in the ground 
will remain undisturbed by human or animal activity, natural settling 
or freeze-thaw cycles, flooding and other extreme weather events, or 
other unforeseen factors. Given that such disturbances can result in 
increased permeability, it was not possible to develop a fixed 
probabilistic distribution of conductivities. Instead, EPA modeled 
conductivity based on the dominant soil megatexture as described in 
Appendix B of the 2014 Risk Assessment. As such, the model assumes the 
ash has been subjected to a similar degree of compaction as the 
surrounding soil. EPA acknowledges that some fly ash is pozzolanic in 
nature. Yet, the commenter provided no information that would indicate 
how common it is for this type of ash, which can be marketed for use in 
concrete, to be placed in CCRMU fills. EPA is also not aware of any 
information that could be used to represent the long-term conductivity 
of this ash when left in the field and exposed to the elements.
    Comment: One commenter contended that EPA had not adequately 
demonstrated that consideration of more recent weather data drawn from 
the latest version of the Hydrologic Evaluation of Landfill Performance 
model would result in consistently higher infiltration rates than 
previously modeled in 2014 for CCR landfills.
    EPA Response: The 2023 Draft Risk Assessment proposed that the 
higher rates of infiltration modeled for certain soil types with the 
new HELP data indicates the potential for higher leaching and risk to 
groundwater than previously modeled in 2014. However, because EPA found 
that the model results from the 2014 Risk Assessment are sufficient to 
support the current rulemaking, the Agency did not conduct the 
additional modeling that would be necessary to refine this draft 
analysis. As a result, EPA does not rely on this particular analysis to 
support the final rule and so it is not included in the 2024 Risk 
Assessment.
    Comment: Several commenters stated that consideration of a limited 
subset of contaminants for groundwater modeling would result in an 
underestimation of risk. These commenters further assert that EPA 
further underestimated risk by not accounting for the effects of 
cumulative exposure to multiple contaminants.
    EPA Response: EPA disagrees that the selection of constituents for 
groundwater modeling resulted in lower risks than would have otherwise 
been identified. The constituents selected for groundwater modeling 
were those found to be risk drivers for unlined surface impoundments in 
the 2014 Risk Assessment, as these are considered the most likely to 
also result in the greatest risks for unlined landfills and comparable 
management units. EPA notes that some of the additional constituents 
raised by commenters had been previously identified as risk drivers 
only for specific CCR types, such as flue gas desulfurization (FGD) 
wastes, which are considered far less likely to be used in CCRMU fills. 
The commenters presented no new information that could alter the 
previous model results and so there is no expectation that inclusion of 
these additional constituents would identify risks higher than those 
already modeled for the relevant CCR types. Some other additional 
constituents raised by commenters lack health benchmarks within the 
Office of Land and Emergency Management (OLEM) hierarchy and so could 
not be quantitatively evaluated. See, 85 FR 72526. Uncertainties 
associated with the selection constituents for modeling is further 
discussed in Section 6 of the 2024 Risk Assessment.
    Comment: Several commenters argued that a modeling horizon of up to 
10,000 years was unrealistic. These commenters stated that such a long 
time frame is not consistent with identifying a reasonable probability 
of adverse effects because there is no reliable way to predict whether 
any receptors will exist that far in the future.
    EPA Response: EPA ran the groundwater model until either the 
observed groundwater concentration at the receptor point reached a peak 
and then fell below a model-specified minimum concentration (1 x 
10-\16\ mg/L), or the model had been run for a time period 
of 10,000 years. This is the same modeling horizon applied in the 2014 
Risk Assessment. The text in the 2024 Risk Assessment has been updated 
to make it clear that the selection of a maximum 10,000-year time 
horizon does not mean that it typically took that long for 
contamination be identified or that all model simulations continue for 
the full 10,000 years. EPA also notes that the time to first exceedance 
of selected risk criteria is typically considerably less than the time 
to the greatest exceedance.
    EPA acknowledges that future groundwater use patterns may shift 
over time as the number and location of receptors changes, and that it 
is unknown whether or how future shifts in receptor locations and other 
surface conditions might affect risk. However, EPA notes that all the 
contaminants associated with CCR are inorganic and so will remain 
present in the environment over the full modeling horizon. As such, a 
longer modeling horizon can provide useful information about the 
potential duration of groundwater contamination in the absence of 
regulation. EPA found that contaminant plumes modeled in MODFLOW did 
not fully dissipate for around 2,300 years for arsenic V and 100 years 
for molybdenum.
    Comment: Multiple commenters argued that EPA was inconsistent with 
the 2014 Risk Assessment and overestimated risks for CCRMU fills by not 
evaluating the interception of groundwater by surface water.
    EPA Response: EPA did not explicitly evaluate interception by 
surface water on groundwater fate and transport in the

[[Page 38965]]

2024 Risk Assessment. As acknowledged by commenters elsewhere, 
facilities have generally not maintained reliable records about the 
location or construction of all CCRMU fills. As a result, it is not 
possible for EPA to develop a representative, probabilistic 
distribution of the distance from these fills to downgradient water 
bodies or offsite receptors. However, given the diversity of reasons 
for such placements listed by commenters, there are few limitations as 
to where these fills might be located onsite. As a result, there is 
greater potential for these fills to be located further away from water 
bodies than disposal units, allowing for further contaminant spread 
prior to any interception. Therefore, the 2024 Risk Assessment 
evaluated the potential magnitude and extent of onsite groundwater 
contamination that could occur in the absence of interception. It is 
considered unlikely that further quantitative evaluation of 
interception would affect the conclusions of the 2024 Risk Assessment. 
The reductions in modeled risks attributed interception in the 2014 
Risk Assessment were predominantly for median risks. However, the 2014 
Risk Assessment still identified high-end risks to offsite receptors, 
and it was these risks that formed the basis for the 2015 CCR Rule. 
Thus, it is similarly unlikely that quantitative evaluation of surface 
water interception would affect the high-end risks reported in the 2024 
Risk Assessment, especially because the current assessment considers 
onsite groundwater quality prior to discharge to a water body. 
Furthermore, as discussed in the 2024 Risk Assessment and in response 
to comments elsewhere, the fact that a contaminant plume that has 
migrated off-site is intercepted by surface water does not mean that 
there is no potential for risk or no need for further action to address 
the presence of groundwater contamination onsite.
    Comment: Some commenters requested clarification on the prevalence 
of different types of liners modeled for the landfills and surface 
impoundments previously excluded from the 2014 Risk Assessment. Citing 
to data relied upon in the 2014 Risk Assessment, one commenter asserted 
that a majority of modeled landfills had some form of liner and that 
national regulations should be based on the risks for all units, rather 
than those that are unlined.
    EPA Response: The handling of liner status for these units was 
described in Section 5 of the 2014 Risk Assessment. Of the units 
evaluated in the 2014 Risk Assessment, approximately 42% of landfills 
and 65% of surface impoundments were modeled as having no engineered 
liner system. Of the previously excluded units summarized in the 2024 
Risk Assessment, approximately 71% of landfills and 57% of surface 
impoundments were modeled as having no engineered liner system. EPA has 
updated the discussion of this issue in the 2024 Risk Assessment to 
better distinguish the specific liner status modeled for these 
different units. Differences in the national risks reported in 2014 and 
2024 are largely attributed to the relative prevalence of engineered 
liners modeled for each. Modeled risks in both assessments are nearly 
the same for the subset of units with no engineered liner.
    Far from being an isolated practice, a substantial fraction of the 
currently operating landfills across the country have no engineered 
liner. Although the 2014 Risk Assessment did model a majority of 
landfills as having some form of engineered liner, data that has become 
available since then indicates a greater proportion of operating units 
lack an engineered liner than EPA previously understood. Furthermore, 
the 2014 Risk Assessment modeled the performance of both clay and 
composite liners based on the assumption of good construction 
practices. However, it has become clear since then that some liner 
systems do not perform as modeled. For example, facility reporting 
shows that around 10% of composite and alternate-lined units have 
already entered into corrective action. Therefore, it is considered 
likely that national risks for both landfills and surface impoundments 
(including the inactive landfills and legacy impoundments subject to 
this final rule) are more similar to those unlined units than 
previously modeled.
    Nevertheless, the 2014 and 2024 Risk Assessments, which provided 
much of the basis for this final rule, modeled the risks associated 
with both lined and unlined units. Under RCRA sections 1008(a)(3) and 
4004(a), EPA establishes national criteria; because the criteria are 
national in scope EPA must evaluate the full range of conditions. In 
addition, EPA must establish requirements that will achieve the 
statutory standard at all sties subject to the criteria--including 
those that pose the greatest risk. Under these provisions, the criteria 
may authorize a CCR unit to continue operating ``only if there is no 
reasonable probability of adverse effects on health and the environment 
from the disposal [or other solid waste management] of solid waste at 
such facility.'' 42 U.S.C. 6903(a)(3), 6944(a). Given the requirement 
that the standard be met at each facility covered by the regulation, it 
is not particularly surprising that the final requirements are driven 
by the higher end risks associated with unlined units--especially as 
the overwhelming majority of legacy impoundments and CCRMU are expected 
to lack the composite liner that would largely mitigate the risks of 
CCR units. But that does not mean that the national regulations are not 
based on the risks for all units.
    Comment: One commenter argued that modeled groundwater 
concentrations and associated risk downgradient of smaller CCRMU fills 
are unrealistic because they are higher than previously modeled for 
landfills and surface impoundments. Other commenters contended that 
modeled groundwater concentrations were unrealistic, citing comparisons 
to monitoring data for all regulated units in a report by the 
Environmental Integrity Project (EIP) \17\ or for some smaller subset 
of units. These commenters calculated summary statistics from 
concentrations reported for site groundwater monitoring wells to assert 
that modeled concentrations were an order of magnitude higher or more 
than the concentrations that have occurred in the field.
---------------------------------------------------------------------------

    \17\ EIP. 2022. ``Poisonous Coverup: The Widespread Failure of 
the Power Industry to Clean Up Coal Ash Dumps.''
---------------------------------------------------------------------------

    EPA Response: The 2014 Risk Assessment modeled risks from landfills 
and surface impoundments to receptors located up to a mile away from 
these units. The 2024 Risk Assessment modeled the magnitude and extent 
of contamination extending from smaller CCRMU fills, including the 
likelihood of exceedance of GWPS at the waste boundary of the unit. It 
is entirely reasonable that concentrations and risk closer to the waste 
boundary are higher than EPA modeled in 2015 up to a mile away from a 
unit.
    EPA disagrees that the modeled groundwater concentrations are 
contradicted by available monitoring data. First and foremost, EPA 
modeled the long-term potential for groundwater contamination that may 
occur in the absence of regulatory action. Thus, monitoring data from 
units of variable age and operational status do not represent a one-to-
one comparison. Second, field monitoring data can diverge from model 
results as a result of improper well installation. As just one example, 
EPA is aware of multiple instances where monitoring wells are located 
far from the waste boundary, in some cases, hundreds of feet away. See, 
for example, 88 FR 55239. Third, EPA used EPACMTP to model

[[Page 38966]]

concentrations along the centerline of the plume and to provide a best 
estimate of contaminant transport potential to inform further modeling 
with MODFLOW. Even if all wells in a network were properly installed 
and spaced, there is no guarantee that any individual well will 
intersect with the exact point of highest concentration; some wells may 
not intersect with the plume at all. Finally, the 90th percentile 
concentration modeled is not intended to correspond precisely to a 90th 
percentile of well concentrations. Instead, it reflects an RME scenario 
that is conservative, while remaining within the range of possible 
high-end exposures. The EIP dataset cited by commenters do show 
multiple instances of well concentrations at individual landfills of 
the same order of magnitude as modeled in the 2024 Risk Assessment or 
even higher. Further, in the case of arsenic, modeled GWPS exceedances 
between 26 and 19 for arsenic III and V are of a similar magnitude as 
the exceedance of 16 estimated by one commenter based on the EIP 
report. Therefore, EPA maintains that the magnitude of modeled 
groundwater concentrations is realistic.
    Comment: Some commenters claimed that EPA had not justified 
modeling groundwater concentrations at fixed distances along the 
centerline of the plume or within the upper five feet of the aquifer 
and had not demonstrated how this approach compares with the 2014 Risk 
Assessment, which modeled concentrations within the top 30 feet of the 
aquifer.
    EPA Response: The goal of modeling with EPACMTP was to identify the 
potential magnitude of GWPS exceedances at the waste boundary and 
potential for contaminant spread to support further modeling with 
MODFLOW. For both goals, a sampling along the centerline of the plume 
and to a depth of five feet was determined to be most relevant portion 
of the aquifer for consideration for the reasons documented in the 2024 
Risk Assessment. Because different scenarios were modeled in the two 
risk assessments, a comparison with the results of 2014 Risk Assessment 
is not relevant here.
    Comment: EPA received several comments regarding a graph from the 
2023 Draft Risk Assessment, which summarized modeled risks from the 
2014 Risk Assessment for unlined landfills as a function of unit size. 
Commenters stated that it demonstrated that risks consistently decline 
below a certain acreage and that smaller units do not warrant 
regulation because they pose less risk. One commenter stated that the 
underlying model runs for the 2014 Risk Assessment were not made 
available alongside the graph and so its validity could not be 
confirmed.
    EPA Response: One purpose of the referenced graph was to 
demonstrate that risks remain above levels of concern over a broad 
range of unit sizes modeled in the 2014 Risk Assessment. However, upon 
further review, EPA has determined that the graph incorrectly 
summarized model results for receptors of all age cohorts into one 
figure. This has the potential to bias the plotted risks low. However, 
filtering the model runs for only (1) unlined landfills, (2) where 
drinking wells are located closer than surface water bodies, and (3) 
where an adult was exposed results in a relatively small number of 
model runs. EPA is concerned that this number of runs is not sufficient 
to reflect national variability or support broader conclusions about 
risk. As such, EPA does not rely on this line of evidence to support 
the final rule and so it is not included in the 2024 Risk Assessment.
    EPA cautions the data presented in the graph was for landfills and 
so use of this graph to draw conclusions about the risks from surface 
impoundments is not appropriate. EPA further cautions that it is not 
appropriate to use the referenced graph to identify a specific unit 
size below which landfill risks are not possible. The graph summarized 
the results of the 2014 Risk Assessment, which modeled risks to offsite 
receptors up to a mile away from the waste boundary. The risks 
identified based on these receptors provided a robust basis for the 
2015 CCR Rule. Yet, this does not mean these are the only relevant 
risks. EPA's longstanding and consistent policy (across numerous 
regulatory programs) has been that groundwater contamination is a 
significant concern that merits regulatory action in its own right, 
whether or not the aquifer is currently used as a source of drinking 
water. The 2024 Risk Assessment identifies the potential for CCRMU 
fills to contaminate groundwater above levels of concern. Where CCR 
landfills and surface impoundments are located at the same sites even 
more extensive contamination can occur as a result of their larger 
size. As such, these disposal units warrant regulation to protect 
groundwater resources, regardless of their size.
    Comment: One commenter questioned why MODFLOW--Unstructured Grid 
(USG) was used to model groundwater transport, stating that MODFLOW 6 
is more commonly used. This commenter also inquired why the model was 
not run in steady-state mode. They further argued that insufficient 
information had been provided to allow for evaluation of the design of 
MODFLOW model runs. Finally, the commenter identified a potential 
discrepancy in the reported model inputs for EPACMTP and MODFLOW.
    EPA Response: MODFLOW-USG was selected for its ability to: (1) 
Simulate flow and transport in both the unsaturated and saturated zones 
without the need for additional modeling packages and (2) Simulate 
groundwater flow and transport sequentially without the need for 
reading cell by cell flow and transport. Steady state simulations were 
not used because they do not provide a time series representation of 
plume evolution. EPA has reviewed the model documentation to ensure 
that this and other relevant information raised by commenters was made 
clear in the 2024 Risk Assessment. However, EPA notes that this and 
much of the other specific information raised by commenters was 
previously described in the 2023 Draft Risk Assessment. EPA did not 
incorporate the full output files for all MODFLOW model runs because 
the file size would become prohibitively large to manage. The level of 
documentation of model inputs and outputs is consistent with that 
provided for EPACMTP. The identified discrepancy between EPACMTP and 
MODFLOW inputs were the result of a typo, which has been corrected.
    Comment: One commenter stated that EPA had not provided sufficient 
evidence to support its conclusion that the location of legacy 
facilities that were not modeled in 2014 could result in somewhat 
higher risks for this subset of units compared to those previously 
modeled units.
    EPA Response: EPA previously found that the locations of legacy 
facilities were clustered in the eastern half of the country. As a 
result, the rates of precipitation at these facilities will tend to be 
higher than modeled for the nation as a whole. Higher precipitation can 
result in greater vertical infiltration and subsequent leakage down to 
groundwater. The Agency has not conducted further sensitivity analyses 
to support this contention, as this argument is not central to the 
findings of either the risk assessment or the rulemaking. Instead, 
discussion in the 2024 Risk Assessment has been updated to clarify that 
the primary finding is that there is no indication based on geography 
that these additional units would be exposed to substantially different 
environmental conditions than EPA modeled in 2014.
    Comment: Multiple industry commenters argued that modeled

[[Page 38967]]

arsenic risks do not warrant regulation because the associated 
concentrations often fall below the current maximum contaminant limit 
(MCL). One commenter noted that 70 percent of runs identified peak 
arsenic concentrations below the MCL at the unit boundary. In contrast, 
environmental advocacy groups stated that cancer risks within the OLEM 
risk range can occur at even lower levels. Another asserted it was 
inappropriate for EPA to identify risk based on modeled concentrations 
above GWPS because corrective action requires ``a statistically 
significant level exceeding the groundwater protection standard.''
    EPA Response: First, EPA notes that arsenic is only one of the 
contaminants modeled. Molybdenum was found to be above the associated 
GWPS on a more frequent basis. Indeed, EPA identified exceedances for 
this contaminant at both the 90th and 50th percentile results. EPA 
disagrees that risks identified below MCLs do not pose a concern. MCLs 
are not purely risk-based and can incorporate other considerations, 
such as the technical feasibility of reliably achieving even lower 
levels. As environmental commenters have pointed out, the arsenic MCL 
in particular represents a concentration that can fall outside the OLEM 
risk range. As such, these standards should be understood as values 
that corrective action must achieve and not levels that never warrant 
concern. Indeed, EPA established GWPS at the unit boundary with the 
intent to limit downgradient transport of contamination above this 
level and prevent the same magnitude of risk identified in the risk 
assessment.
    EPA also disagrees that a statistically significant increase above 
GWPS is an appropriate standard for risk modeling. It is not clear, nor 
do commenters articulate, how such a statistical analysis would be 
conducted as part of the model. Thus, EPA believes this comment 
represents a general misunderstanding of both groundwater monitoring 
programs and probabilistic analysis. Statistical analysis is used in 
groundwater monitoring programs because factors, such as natural 
fluctuations in groundwater and uncertainty from sampling or laboratory 
analysis procedures, can introduce variability into the broader 
dataset. In this context, statistical analysis allows evaluation of the 
broader data and identification of an exceedance of GWPS with a 
specified level of certainty. However, numerical models are not subject 
to the same constraints. A model tracks the fate and transport of all 
contaminant mass from the point of release to the point of exposure. 
Therefore, no additional steps required to confirm that an identified 
exceedance of GWPS resulted from leakage from the modeled unit.
    Comment: Several commenters stated that the toxicity value used for 
arsenic underestimated risks from groundwater, citing draft values they 
assert would increase modeled arsenic risks by an order of magnitude or 
more.
    EPA Response: The Agency's current risk estimates are based on the 
same cancer slope factor of 1.5 mg/kg/d-\1\ for arsenic in 
EPA's Integrated Risk Information System (IRIS). EPA is currently in 
the process of reviewing this slope factor and has released a draft 
toxicological review, which, if finalized without revision, would 
increase the individual risk estimates for arsenic by a factor of 
approximately 35. See, 88 FR 71360. However, the Agency has not yet 
finalized this updated IRIS reassessment, and EPA cannot base a final 
decision on a draft IRIS value that is subject to revision. Nor did EPA 
receive any other information during the development of this final rule 
that would help to resolve this uncertainty. The current IRIS values 
thus represent the best data available to the Agency until the IRIS 
reassessment is complete.
d. Comments Related to Supplemental Risk Assessment Soil Model
    Comment: One commenter contended that radionuclides and non-
radionuclides have different health endpoints and so it is not 
appropriate to treat the resulting risks as additive.
    EPA Response: EPA disagrees that it is inappropriate to consider 
the cumulative risk from chemical and radiological contaminants. EPA 
policy is to treat the risk resulting from exposure to multiple 
carcinogens as additive.\18\ Agency policy is also to evaluate the 
risks from exposure to radionuclides in the same manner as chemical 
contaminants.\19\ Therefore, it is appropriate to evaluate the 
cumulative cancer risk from chemical and radiation contaminants. 
However, EPA notes that considering chemical and radiological risks 
separately would not alter the overall conclusions of the analysis, as 
each have demonstrated potential to individually result in risk 
exceeding EPA's levels of concern. Uncertainties associated with 
umulative risk is further discussed in Section 6 of the 2024 Risk 
Assessment.
---------------------------------------------------------------------------

    \18\ U.S. EPA. 1989. ``Risk Assessment Guidance for Superfund 
Volume I Human Health Evaluation Manual (Part A).'' EPA/540/1-89/
002. Prepared by the Office of Emergency and Remedial Response, 
Washington, DC. December.
    \19\ U.S. EPA. 2014. ``Radiation Risk Assessment at CERCLA 
Sites: Q&A.'' OSWER 9285.6-20. Prepared by the Office of Land and 
Emergency Response. Washington, DC. June.
---------------------------------------------------------------------------

    Comment: EPA received comments that argued the U.S. Geological 
Survey coal quality (COALQUAL) database does not adequately account for 
several factors that may affect bulk content of the resulting ash, such 
as: CCR type, regional variability, coal rank, mining practices, coal 
preparation prior to combustion, and the presence of unburnt carbon 
remaining after combustion. Another commenter stated that because the 
risk assessment addresses historical disposal of CCR, sampling of the 
COALQUAL database should be updated to reflect production over time, 
rather than current production. Finally, one commenter argued that 
differences identified between activity calculated from COALQUAL data 
and measured elsewhere in the literature demonstrates that handling of 
COALQUAL data is likely to overestimate concentrations in the ash.
    EPA Response: The Agency acknowledges that the bulk contaminant 
content of specific CCR samples can be influenced by a range of 
factors, such as the manner in which a coal sample is prepared and 
combusted. As detailed in Section 6 of the 2024 Risk Assessment, EPA 
considered the information provided by commenters on the potential for 
mining practices, residual unburnt carbon, and coal washing to affect 
estimated ash concentrations and concluded these factors are likely to 
have a minimal or inconsistent effect on overall distribution of 
concentrations. EPA did determine that concentrations of some 
contaminants are sensitive to differences in region and coal rank and 
so reviewed the Energy Information Administration (EIA) coal production 
reports referenced by commenters when updating the weighting of 
available samples.
    For purposes of modeling groundwater exposure, EPA did not use the 
COALQUAL database to estimate the leachable content of CCR in the 2024 
Risk Assessment. Previous reviews of EPACMTP summarized in the 2014 
Risk Assessment did not identify leachable content as among the 
sensitive model parameters. Even at lower bulk concentrations, there is 
often sufficient soluble mass present to support sustained leaching. 
Instead, EPA represented leachable content using available LEAF data in 
a manner

[[Page 38968]]

consistent with the 2014 Risk Assessment and Agency guidance.\20\
---------------------------------------------------------------------------

    \20\ U.S. EPA. 2019. ``Leaching Environmental Assessment 
Framework (LEAF) How-To Guide: Understanding the LEAF Approach and 
How and When to Use It.'' SW-846 Update VII. Prepared by the EPA 
Office of Land and Emergency Management. Washington, DC. May.
---------------------------------------------------------------------------

    For purposes of modeling soil exposure, EPA retained use of the 
COALQUAL database in the 2024 Risk Assessment to calculate the bulk 
content of thorium and uranium of CCR. In this instance, use of 
COALQUAL provides information about the relative levels of each 
contaminant, which allowed for a more refined estimate of cumulative 
exposure that provides a more direct comparison with relevant 
benchmarks. As discussed in Section 6 of the 2024 Risk Assessment, EPA 
also considered available EIA data when updating the calculation of 
bulk content for these two contaminants and found that concentrations 
of both are less sensitive than other contaminants to regional 
geography. Therefore, further efforts to refine these calculations are 
considered unlikely to result in changes that would affect the overall 
conclusions of the evaluation.
    The bulk contaminant content calculated from COALQUAL represents a 
mixture of fly ash and either bottom ash or boiler slag, collectively 
referred to in the 2024 Risk Assessment as the ``whole ash.'' Because 
fly ash is generated in the greatest volumes during coal combustion, 
the calculated bulk content primarily reflects this type of CCR. 
However, other available data sources indicate that the activity of fly 
ash and bottom ash are not substantially different. EPA has seen no 
indication that the activity of boiler slag would differ markedly from 
that of bottom ash. The whole ash does not include any CCR generated by 
scrubber systems and similar pollution control technologies. However, 
these CCR types are not considered relevant to the evaluation of CCRMU 
fills. EPA further discusses the uncertainties associated with these 
different types of CCR in Section 6 of the 2024 Risk Assessment.
    Based on the comments received, EPA reviewed the available data on 
radioactivity drawn from the literature. This review led to the removal 
of several samples that were determined to be duplicative and removed 
all the data for one study because it was determined to not be 
representative of the broader ash generated at the facility. 
Altogether, the data removed represent a small fraction of the overall 
dataset. This review also identified some inaccuracies in how samples 
were described and averaged to avoid biasing the overall dataset toward 
individual facilities that reported a greater number of samples. This 
had resulted in more samples being averaged together than was intended. 
The database presented as part of the 2024 Risk Assessment has been 
updated along with a summary of these updates. Following these 
corrections, the updated summary statistics for thorium align more 
closely with those calculated with COALQUAL. Therefore, there is 
general agreement between these two datasets. It is inevitable there 
will be some differences between datasets developed through different 
methodologies. In particular, any individual study may not reflect the 
full variability of coal produced over time. However, the magnitude of 
differences between activities drawn from COALQUAL and the broader 
literature are small on an absolute basis and consequently would not 
affect the overall conclusions of the risk assessment. Therefore, EPA 
concludes that COALQUAL can provide a reasonable estimate of both 
median and high-end ash activity.
    Comment: One commenter critiqued multiple individual model inputs 
used in RESRAD as likely to overestimate potential for radon exposure. 
They also stated that the risk assessment should consider an additional 
scenario with RESRAD of CCR disposed at the ground surface to provide a 
consistent frame of reference to compare risk results obtained from 
RESRAD and the preliminary remediation goal (PRG) calculator. Other 
commenters separately commented that the assumed presence of some soil 
cover is inappropriate, referencing one CCRMU purported to have been 
placed with the intent to level out the ground surface and without any 
additional soil cover.
    EPA Response: EPA has not established default parameters for 
modeling of radon fate and transport. Nor is there currently enough 
information available on a national scale to develop distributions that 
could be sampled probabilistically. Instead, EPA previously conducted a 
deterministic analysis for radon exposure by specifying high, moderate, 
and/or low values for model inputs to capture the range of potential 
exposure. EPA first modeled risk with all inputs set to moderate values 
to identify a baseline risk more representative of the central 
tendency. From this baseline, EPA adjusted each individual input to 
lower or higher values to better understand which inputs exert the 
greatest influence on modeled risks and support development of an RME 
scenario. However, EPA ultimately concluded that the rate of radon 
emanation from CCR is not distinguishable from background soil and so 
the Agency did not develop this RME scenario or draw final conclusions 
about risk from radon exposure. For this same reason, EPA did not 
retain the quantitative evaluation of radon in the 2024 Risk 
Assessment.
    Some CCRMU fills may currently be uncovered, but EPA was not able 
to confirm the status of the specific unit identified by the commenter 
based on the information provided. Nevertheless, EPA maintains it is 
unlikely that future residential construction would occur in the 
absence of some initial soil cover. It is generally anticipated 
residential construction sites will cover any exposed land with topsoil 
or turf to support uniform lawn growth. However, this does not 
guarantee this soil cover will be adequately maintained by residents 
into the future. As such, EPA agrees it is appropriate to evaluate a 
scenario of CCR without any soil cover to provide a bounding estimate 
of potential risk and a more direct link between the primary and 
sensitivity analyses. This updated scenario is discussed in Section 6 
of the 2024 Risk Assessment.
    Comment: Some commenters raised concerns about the sensitivity 
analysis conducted with the PRG calculator. One commenter asserted that 
the PRG calculator is intended for use with contaminated soils and is 
inappropriate for comparison against undiluted CCR. This commenter 
further argued that the sensitivity analysis conducted with the PRG 
calculator is overly generic and did not incorporate scenario-specific 
inputs, such as the potential for greater soil cover, shorter exposure 
duration, and ability of radon to emanate from CCR. Finally, this 
commenter stated that the degree of mixing of soil with CCR would not 
result in activities higher than either background or applicable or 
relevant and appropriate requirements (ARARs), concluding that the 
evaluation of radiation risk should consider contributions from 
background soils when presenting risk results. Another commenter stated 
that the ARAR was only exceeded around the 90th percentile 
concentrations and that regulation based on 90th percentile 
concentrations is not appropriate.
    EPA Response: EPA disagrees that the PRG calculator is not 
applicable to the modeled scenario of CCR intermixed with soil. The 
commenters provide no rationale for this assertion beyond the fact that 
the PRG calculator nominally identifies soil as an environmental media 
of interest. This is reasonable as it would quickly become overwhelming 
to identify a comprehensive list of sludges, sediments, and other soil-
like

[[Page 38969]]

materials that might be encountered at cleanup sites. EPA notes that 
the exposure assumptions incorporated into the PRG calculator are 
equally relevant for CCR intermixed with soil. CCR consist of small 
particulates that can be readily intermixed with the soil and result in 
exposures through the exact same routes, specifically incidental 
ingestion and direct exposure to gamma radiation.
    EPA also disagrees that the analysis of exposure to CCR mixed with 
soil is overly simplistic. First, the presence of additional cover soil 
is already considered in the main analysis and is not relevant to the 
types of exposures explicitly considered in the sensitivity analysis. 
Second, because EPA concluded the rate of radon emanation from CCR and 
soil were not distinguishable, the sensitivity analysis explicitly does 
not incorporate risk from inhalation of radon gas. Only a relatively 
small fraction of the radon generated from fly and bottom ash is 
expected to escape into the ambient air and these losses can be 
counteracted by upward migration from deeper ash. Therefore, it is 
unlikely that further consideration of radon emanation would have 
substantial impacts on exposures through incidental ingestion or direct 
gamma exposure. Third, the model parameters used to characterize 
exposure to gamma radiation in the PRG calculation are generally the 
same as in RESRAD and other available models. Finally, exposure factors 
selected for use in the PRG calculator are consistent with Agency 
policy for characterizing an RME scenario and many of the remaining 
parameters are based on extensive modeling.21 22 23
---------------------------------------------------------------------------

    \21\ Oak Ridge National Laboratory. 2014. ``Area Correction 
Factors for Contaminated Soil for Use in Risk And Dose Assessment 
Models.'' ORNL/TM-2013/00. Oak Ridge, TN. September.
    \22\ Oak Ridge National Laboratory. 2014. ``Gamma Shielding 
Factors for Soil Covered Contamination for Use in Risk and Dose 
Assessment Models.'' ORNL/TM-2013/00. Oak Ridge, TN. September.
    \23\ Oak Ridge National Laboratory. 2020. ``Bateman Equation 
Adaptation for Solving and Integrating Peak Activity into EPA ELCR 
and Dose Models.'' ORNL/TM-2020/1780. Oak Ridge, TN. September.
---------------------------------------------------------------------------

    EPA generally only considers contributions from disposed wastes to 
risk when conducting national risk assessments under RCRA. Background 
concentrations may contribute to risk when present and can sometimes be 
higher than concentrations modeled in a risk assessment. Although 
constituent concentrations in undisturbed environmental media can be 
highly variable, they are often relatively low in concentration. As a 
result, consideration of these concentrations would generally have no 
impact on the overall conclusions of a national risk assessment. 
Therefore, consideration of background concentrations is more 
appropriate on a site-specific basis when risk managers are determining 
the need for and scope of corrective action. EPA recognizes that a 
focus on background is more common for discussion of radioactivity, 
particularly when providing context for the associated risks to the 
broader public. However, as one point of reference, EPA has found that 
the median activities of fly and bottom ashes already fall close to the 
standard of 5 pCi/g radium-226+228 above background soil, which has 
been adopted as an ARAR for some cleanups under Superfund and State 
programs (i.e., around 4.3 pCi/g higher).\24\ Additionally, EPA has 
found that high-end radium-226+228 activity in CCR has the potential to 
be nearly 10 pCi/g higher than typical background soil. Thus, there is 
real potential for mixing of CCR with soil to further increase any risk 
already associated with background.
---------------------------------------------------------------------------

    \24\ U.S. EPA. 1998. ``Use of Soil Cleanup Criteria in 40 CFR 
part 192 as Remediation Goals for CERCLA Sites.'' OSWER Directive 
9200.4-25. Office of Emergency and Remedial Response and Office of 
Radiation and Indoor Air. Washington, DC. February.
---------------------------------------------------------------------------

    Commenters are correct that mixing small quantities of CCR with 
soil may not result in a surface soil activity above the ARAR. For 
high-end CCR activity, this would require a roughly equal mixture of 
soil and ash. However, risks are still possible at activities below the 
ARAR. The PRG calculator estimates that an increase of only 1.13 pCi/g 
of the thorium-232 decay chain or 1.45 pCi/g of the uranium-238 decay 
chain in surface soils could increase cancer risk for residential 
receptors by 1 x 10-\4\. Such risks can result from 
relatively low mixtures of CCR and soil, which are possible if ash 
beneath the soil surface is disturbed. As a result, EPA has identified 
ARAR of 5 pCi/g above background as equally applicable to subsurface 
contamination that may be disturbed in the future and concluded ``it 
would not generally be appropriate to allow backfilling with material 
with concentration higher than 5 pCi/g.'' Uncertainties associated with 
background concentrations are further discussed in Section 6 of the 
2024 Risk Assessment.
    Comment: One industry commenter presented an analysis they had 
conducted comparing the concentrations of certain inorganic 
constituents in CCR to soil screening levels. The commenter contended 
this analysis demonstrated that ``even daily direct contact to trace 
elements in coal ash would not pose a significant risk to human 
health.''
    EPA Response: EPA did not evaluate the potential soil risks for 
human health associated with many of the constituents considered in the 
cited analysis. The Agency believes that any risk from additional 
constituents would be mitigated by the rule requirements that address 
the risks identified for radionuclides. However, EPA notes that the 
cited analysis is not sufficient to demonstrate a lack of risk for 
these additional constituents on a national scale. The ash 
concentrations reported for some constituents are already near or above 
the health benchmarks, indicating some potential for risk. Further, the 
reported ash concentrations are based on samples from a limited number 
of geographically constrained facilities. As a result, the reported 
concentrations may not reflect the broader variability of potential 
concentrations from across the region or country. In particular, EPA 
notes there is evidence in the regulatory record of arsenic 
concentrations approaching an order of magnitude higher than considered 
in this analysis.
    Comment: Several commenters argued that EPA underestimated risk by 
not considering other potential exposure pathways, specifically 
inhalation of loose CCR.
    EPA Response: EPA selected direct exposure gamma radiation and 
incidental ingestion of soil as the pathways for evaluation because 
these represent the most direct routes of exposure to contamination in 
the soil. EPA agrees that inhalation is another pathway through which 
future receptors could be exposed if CCR becomes intermixed with 
surface soil. Quantitative evaluation of this pathway would require 
additional model inputs that could further increase the uncertainty of 
results on a national scale, such as the degree of vegetative cover and 
mean wind speed. However, EPA notes the default PRGs for inhalation of 
the uranium-238 decay chain in secular equilibrium is nearly three 
orders of magnitude higher than for external exposure to gamma 
radiation and two orders of magnitude higher than for incidental 
ingestion of soil. As a result, it is unlikely consideration of this 
pathway would substantially increase calculated risk. Therefore, this 
pathway does not represent a major source of uncertainty in the 
evaluation. EPA acknowledges that there may be other exposure pathways 
that could occur if CCR is mixed with surface soil. These are further 
discussed in Section 6 of the 2024 Risk Assessment.

[[Page 38970]]

e. Comments Related to Site Monitoring Data
    Comment: Some commenters stated that, as part of any further risk 
assessment efforts, EPA should incorporate data that have been 
collected as part of the monitoring programs required by either the 
2015 CCR Rule or prior State programs. Such data might include site 
hydrogeology from borings around the units and groundwater quality 
sampled from monitoring wells. These commenters claimed these data are 
more recent and more relevant to characterizing the actual nature and 
extent of contaminant release at individual sites.
    EPA Response: There are multiple reasons why it is neither 
practical nor prudent to incorporate site-specific monitoring data into 
national fate and transport modeling. First, there are documented 
concerns about the quality and reliability of these data. For example, 
EPA has identified significant deficiencies in the monitoring networks 
at each facility for which the Agency has completed reviews under the 
Part A (85 FR 53516, August 28, 2020) and Part B (85 FR 72506, November 
12, 2020) Rules. It is unlikely such deficiencies are isolated to this 
specific subset of facilities. Monitoring wells that are located too 
far apart, installed in the wrong aquifer, or otherwise inadequately 
installed would result in data that are incomplete or unrepresentative 
of relevant site conditions. Thus, use of these data would require 
thorough review prior to use. Much of the site characterization data 
are not required to be posted on facility websites and so would take 
substantial time to compile and review for the over 1,000 individual 
landfills and surface impoundments. Further, it is highly unlikely that 
any identified deficiencies could be remedied within a reasonable 
timeframe.
    Second, the hydrogeologic data that have been collected in support 
of well installation can provide an incomplete or erroneous picture of 
site conditions for the purpose of fate and transport modeling. For 
example, at sites with lower conductivity soils, EPA has previously 
raised concerns that collection of hydrogeologic data with a focus on 
characterizing the predominant soil type can underestimate the 
prevalence of more localized deposits of higher conductivity soil and 
other discontinuities that can serve as preferential flow pathways to 
groundwater. See, 85 FR 72519. Therefore, the current approach to 
probabilistic characterization of soil and aquifer characteristics 
using more local data sources is believed to provide the most reliable 
means to capture the potential variability of conditions across 
different facilities and represent contaminant fate and transport on a 
national scale. Furthermore, EPA notes that consideration of more site-
specific data would not be expected to change the fact many units are 
known to be constructed on relatively permeable soils. As a result, 
further refinements on the hydrogeology modeled at each individual site 
is unlikely to alter overall model results, which show contaminants can 
escape from these units and spread considerable distances through 
groundwater.
    Third, groundwater monitoring only provides a snapshot in time of 
groundwater concentrations at each well location. It is not obvious, 
nor do commenters articulate, how these data would be applied to model 
long-term unit leakage. Factors such as natural fluctuations in 
background groundwater concentrations make it difficult to apportion 
measured concentrations from individual sampling events into the 
specific contributions from background and unit leakage. That is why 
groundwater monitoring programs rely on statistical analysis of data 
across numerous sampling events to make a binary determination whether 
or not contaminant concentrations downgradient of a unit have increased 
above background and GWPS. Even if it were practical to utilize these 
monitoring data, groundwater samples do not provide broader information 
about the progression of leakage over time. Specifically, groundwater 
samples do not provide information on the magnitude of source leachate 
concentrations, how long the unit has been leaking, or any indication 
of the potential magnitude and extent of contamination in the future. 
EPA modeling previously showed that the magnitude and extent of a plume 
may not peak until decades or centuries after the unit first beings to 
leak. As a result, incorporation of groundwater monitoring samples into 
a model would require a number of additional assumptions about the site 
characteristics and conditions that could substantially increase the 
overall uncertainty of model results.
    Finally, EPA is not aware of similar site-specific data available 
for the subset of smaller CCRMU intended for purposes other than 
disposal. As several commenters have acknowledged, facilities have not 
typically maintained reliable records of the locations of all these 
smaller units. Thus, any modeling of these units must, by necessity, 
draw on other datasets to characterize the potential for environmental 
release and subsequent contaminant fate and transport.
f. Comments Related to Additional Risk Drivers
    Comment: Multiple commenters asserted that risks higher than those 
modeled in the 2014 Risk Assessment are unlikely for landfills. One 
commenter stated that the previous risks modeled for unlined landfills 
are ``only slightly above'' the point of departure at 2 x 
10-\5\ and so, even if most CCRMU landfills are unlined, it 
would not result in risks higher than this value.
    EPA Response: The national risks reported in the 2014 Risk 
Assessment were based on the understanding of relative liner prevalence 
at the time of that assessment. However, it has since become clear that 
an even greater proportion of regulated unit have no engineered liner 
and there is no evidence that CCRMU landfills are lined to any greater 
degree. Additionally, EPA notes that the 2014 Risk Assessment modeled 
both clay-lined and composite-lined units under the assumption of good 
construction practices that achieved the regulatory performance 
standard. However, it has become clear since then that some liner 
systems do not achieve this standard. For example, facility reporting 
shows that around 10% of regulated units with composite or alternate 
liners have already entered into corrective action. Therefore, even for 
those units that do have some form of engineered liner, there is 
potential for national risks to be higher than previously modeled. For 
all these reasons, national risks for both currently regulated and 
CCRMU landfills are only expected to be more similar to those 
previously modeled for unlined landfills. Furthermore, EPA has 
identified additional factors that have the potential to result in even 
higher risks than modeled, but that could not be fully quantified as 
part of either the 2014 or 2024 Risk Assessment. These include co-
disposal with coal refuse and disposal in contact with the water table. 
The greater prevalence of unlined units makes it even more likely these 
additional factors will occur at unlined units. The combination of 
these factors has the potential to result in national risks even higher 
than previously modeled.
    Comment: One commenter acknowledged that the 2014 Risk Assessment 
had demonstrated the potential for co-disposal with coal refuse to 
increase risk from surface impoundments. However, multiple others 
argued that the same assessment shows that neither co-disposal with 
coal

[[Page 38971]]

refuse nor extreme pH conditions increase risks for landfills. 
Specifically, commenters pointed to one sensitivity analysis summarized 
in Table 5-6 of the 2014 Risk Assessment that concluded modeled risks 
did not exceed the point of departure for any subset of the modeled pH 
conditions. One commenter argued the Agency's conclusions are not based 
on actual observations of CCR porewater and groundwater quality at 
sites where coal refuse is managed. This commenter stated that not all 
units that accepted coal refuse will contain enough to affect the 
broader chemistry of the unit and not all coal refuse will contain 
enough pyrite to influence pH. This commenter further argued that, 
where acidic conditions and higher leachate concentrations do occur, it 
will not necessarily result in higher downgradient groundwater 
concentrations due to other site-specific factors. To support this 
argument, the commenter summarized findings from multiple EPRI reports 
that analyzed field samples from around several landfills and surface 
impoundments believed to have accepted coal refuse.
    Response: These commenters misrepresent the findings of the 
referenced sensitivity analysis. This analysis represents a parsing of 
groundwater model runs conducted in 2014 as a function of leachate pH. 
This analysis incorporates model results for a substantial number of 
lined units, which can mask the effects of leachate pH due to the low 
overall leakage rates from these units. As such, this sensitivity 
analysis does not support any conclusions about the impacts of pH on 
risks from unlined units. Further, very few model runs were conducted 
at highly acidic pH; the sensitivity analysis did not summarize any 
results for a pH lower than around 4. Thus, this analysis also does not 
support any conclusions about the risks associated with highly acidic 
conditions.
    Available LEAF leachate data used to model landfills show that many 
constituents, including arsenic, can leach at highest concentrations 
near one or both extremes of the pH scale. The effects of these higher 
concentrations are reflected in the sensitivity analysis, with higher 
risks observed around a highly basic pH of 13. Therefore, this 
sensitivity analysis is consistent with the broader risk record and 
shows that extreme pH conditions can result in higher risk.
    The commenters are also incorrect that the risk record is not based 
on observations of CCR porewater. EPA relied on empirical measurements 
of porewater to support modeling of surface impoundments in 2014, which 
included samples co-disposed with coal refuse. As acknowledged by some 
commenters, these data supported identification of higher risks from 
these co-disposed wastes in impoundments. Corresponding pH data are not 
available for every porewater sample, but available data do show the 
potential for highly acidic pH around 1, roughly equivalent to stomach 
acid. The cited EPRI reports do not contradict the finding that co-
disposal can affect CCR leaching behavior. As summarized by the 
commenter, these reports found that a third of units had impacts to 
unit pH and porewater chemistry. Individual units had potential or 
confirmed impacts on groundwater quality, causing at least one to 
trigger remedial measures by the facility. EPA further notes that these 
reports provide only a snapshot in time of the environmental impacts 
associated with disposal in this subset of disposal units. As a result, 
there remains potential for future releases beyond the waste boundary 
if these conditions persist.
    Comment: Multiple commenters asserted that waste disposed below the 
water table would not result in higher risks from surface impoundments 
than previously modeled in the 2014 Risk Assessment. These commenters 
generally argued the hydraulic head present in an operating impoundment 
from ponded wastewater will result in greater leakage than groundwater 
flowing through a unit. One commenter presented a hypothetical 
comparison of the relative hydraulic flux from a unit due to ponded 
water, infiltrating precipitation, and contact with groundwater to 
argue that the presence of a ponded water would result in higher 
leakage. Others pointed to analyses from the 2014 Risk Assessment, 
which compared leakage from surface impoundments before and after 
dewatering, to argue that risks from impoundments remaining in 
groundwater would be lower. Others further argued that the lower 
hydraulic conductivity of some ash would limit flow through the 
impoundment and cause groundwater to preferentially flow around the 
unit.
    Several commenters presented data from groundwater monitoring 
conducted at individual units to assert that risks are more likely to 
result from the hydraulic head in active impoundments than the 
intersection of waste with the water table. The presented data depict 
concentrations of boron, a highly soluble constituent that one 
commenter noted was selected for its ``insensitivity to redox 
conditions.'' These plots generally show concentrations of boron to 
decrease over time after the impoundments were taken out of service, 
though that pattern was not universal. Some commenters went further, 
concluding that eliminating the hydraulic head in the unit would allow 
any prior groundwater contamination to naturally attenuate. Conversely, 
other commenters pointed to a documented case study where groundwater 
concentrations increased after ponded water was drained to contend that 
contact with the water table can result in higher releases.\25\
---------------------------------------------------------------------------

    \25\ EPRI. 2001. ``Evaluation and Modeling of Cap Alternative at 
Three Unlined Coal Ash Impoundments.''
---------------------------------------------------------------------------

    EPA Response: A number of the commenters misconstrue the findings 
of the 2014 Risk Assessment, which did not include any assessment of 
the effects of CCR disposal within the water table. EPA was unable to 
quantitatively model the risks associated with this management practice 
because there was little data on how common the practice was or the 
extent to which it would affect groundwater chemistry. Instead, these 
commenters are referring to a comparison of the risks resulting from 
surface impoundments during operation and post-closure (i.e., after 
free liquids had been eliminated consistent with Sec.  
257.102(d)(2)(i)) that was undertaken to understand if only modeling 
these units only during operation might underestimate peak risks. EPA 
only concluded that continued leakage after elimination of free liquids 
and closure would rarely result in higher peak risks. Thus, this 
assessment did not consider the effects of disposal below the water 
table or draw any conclusions about the risks associated with this 
practice.
    When waste is managed above the water table, any leakage out of the 
unit must first infiltrate down through unsaturated subsurface soils 
and then mix with groundwater before it can flow beyond the waste 
boundary. As a result, downgradient groundwater concentrations can end 
up substantially lower than the original leachate concentration. In 
contrast, when waste is disposed below the water table, the entire 
volume of groundwater in contact with the CCR and all water 
infiltrating from above would become undiluted leachate. As the 
thickness of CCR below the water table increases, the volume of 
leachate generated can increase substantially based on the sheer size 
of these disposal units. There is no evidence the properties of CCR 
would reliably limit transport of this leachate away from the unit. 
Rather, the hydraulic gradient of the aquifer will continue to drive 
continued flow

[[Page 38972]]

through the unit. The hydraulic conductivity of different CCR overlaps 
with that of common aquifer materials. Even in instances where the 
average conductivity within a unit is lower than the surrounding 
aquifer, these units often contain different ash types and other 
wastes. This can lead to stratification within the unit that creates 
regions of higher conductivity and allows for greater flow. For all 
these reasons, there is potential for sustained leakage from units when 
waste is disposed below the water table. Whether or not the magnitude 
of this continued leakage is greater than from water ponded in an 
impoundment does not address the potential for such leakage to cause a 
release or sustain one that began when water was still ponded in the 
unit. Such comparisons also ignore that the waste would also be in 
contact with groundwater while the unit operates, greatly increasing 
the likelihood of groundwater mounding around the impoundment and 
increased contaminant transport in all directions.
    It is not feasible to draw conclusions based on the small and 
curated sample of units presented by commenters. Various factors can 
complicate any interpretation of the presented graphs. First, boron is 
a highly soluble constituent that can washout at high concentrations 
into small amounts of water. Thus, the extent to which decreases in 
concentration over timeframes of a long as a decade or more simply 
represent the depletion of this highly soluble constituent from the ash 
is unclear. Second, unit geometry may not be uniform and consistently 
intersect with the groundwater table, resulting in more spatially 
isolated releases that cause higher concentrations in some wells and 
not others. Third, at sites with intermittent contact with groundwater, 
predefined sampling dates may not align with periods when contact with 
groundwater occurs. Therefore, it is not possible to draw meaningful 
conclusions, either at these sites or more broadly, based on the data 
provided. As pointed out by other commenters, there are also examples 
available where sustained contract with groundwater after a unit is 
drained resulted in increased groundwater concentrations of other 
Appendix III constituents.
    The fact that downgradient concentrations have decreased at some 
impoundments after the unit was drained despite ongoing contact with 
groundwater does not prove such reductions will be sustained or further 
groundwater releases will not occur. As one EPRI report concluded, 
``the existence of saturated ash will greatly reduce the effectiveness 
of any cap design when the facility is underlain by geologic materials 
with high hydraulic conductivity, because groundwater will continue to 
leach ash constituents.'' \26\ Thus, removal of ash from groundwater 
may be the only reliable means of source control for these units.
---------------------------------------------------------------------------

    \26\ EPRI. 2001. ``Evaluation and Modeling of Cap Alternative at 
Three Unlined Coal Ash Impoundments.''
---------------------------------------------------------------------------

    Comment: Several commenters agreed that use of porewater to 
represent leakage from impoundments is appropriate. However, these 
commenters also raised concerns that available porewater data collected 
during the active life of an impoundment may underestimate the risks 
associated with legacy impoundments because it may not accurately 
reflect leachate concentrations after the unit has ceased operation. As 
one example, they cited potential for reducing conditions to form 
through prolonged contact between waste and groundwater.
    By contrast, one commenter asserted that elevated arsenic 
concentrations identified in the two journal articles EPA referenced in 
the proposal are only representative of that one site and that the 
majority of available impoundment porewater data have lower 
concentrations than reported in those articles.27 28 The 
commenter also noted the data presented in the journal articles were 
collected in support of an EPRI report, which found these 
concentrations had not translated to exceedances of GWPS in 
downgradient wells.\29\ Based on this finding, the commenter concluded 
leachate concentrations alone are not a reliable indicator of which 
units will cause groundwater contamination due to variable site 
geochemistry and hydrogeology.
---------------------------------------------------------------------------

    \27\ Wang, X., A.C. Garrabrants, Z. Chen, H.A. van der Sloot, 
K.G. Brown, Q. Qiu, R.C. Delapp, B. Hensel, and D.S. Kosson. 2022. 
``The Influence of Redox Conditions on Aqueous-Solid Partitioning of 
Arsenic and Selenium in a Closed Coal Ash Impoundment.'' Journal of 
Hazardous Materials. 428:128255.
    \28\ Wang, X., H.A. van der Sloot, K.G. Brown, A.C. Garrabrants, 
Z. Chen, B. Hensel, and D.S. Kosson. 2022. ``Application and 
Uncertainty of a Geochemical Speciation Model for Predicting 
Oxyanion Leaching from Coal Fly Ash under Different Controlling 
Mechanisms.'' Journal of Hazardous Materials. 438:129518.
    \29\ EPRI. 2020. ``Leaching, Geotechnical, and Hydrologic 
Characterization of Coal Combustion Products from a Closed Coal Ash 
Impoundment.''
---------------------------------------------------------------------------

    EPA Response: EPA agrees that porewater samples remain the best 
available data to represent leakage from operating surface 
impoundments. These field samples provide empirical data on leakage 
from various mixtures of CCR and other wastes managed under 
consistently saturated conditions. EPA also acknowledges there can be 
uncertainties associated with field data submitted to the Agency, which 
might lead to an underestimation of concentrations in the field. One 
example is the potential for stronger reducing conditions to form after 
a unit has been closed as a result of less oxygenated water 
infiltrating through the unit. As acknowledged by commenters, however, 
there is not sufficient data to characterize the magnitude or extent of 
such conditions on a national basis. Therefore, the impact of this 
uncertainty is not known.
    EPA disagrees that the arsenic concentrations identified in the 
referenced studies should be considered an isolated occurrence. These 
studies clearly demonstrate that: (1) Sustained contact with 
groundwater can result in stronger reducing conditions than dry 
management, (2) Reducing conditions can cause higher leaching of 
arsenic, and (3) LEAF methods can underestimate actual leaching from 
CCR under reducing conditions by as much as an order of magnitude. 
Given that disposal beneath the water table is a more common practice 
than previously understood, there exists the real potential for higher 
leachate concentrations in the field than previously modeled, 
particularly at landfills modeled with LEAF data.
    EPA does agree that initial leachate concentrations are not the 
sole determining factor for contaminant fate and transport. As 
discussed in response to previous comments, this fact is reflected in 
Agency modeling. Individual model runs with the highest leachate 
concentrations are not always those with the highest risk. However, 
factors that will tend to push the overall distribution of leachate 
concentrations higher will also tend to push modeled nationwide risks 
higher because of the greater likelihood that higher leachate 
concentrations will occur at sites where these concentrations can more 
readily spread. Thus, the greater prevalence of units in contact with 
groundwater has the potential to result in higher risks on a national 
scale than previously modeled.
    Finally, EPA notes that groundwater monitoring only represents a 
snapshot in time and does not necessarily provide any indication of the 
potential for future contamination. In the case of the studied unit, it 
is not known whether reducing conditions formed during or after 
operation. As such, there remains potential for future releases if the 
unit remains in contact with groundwater

[[Page 38973]]

and continues to leak such elevated arsenic concentrations.
g. Comments Related to Complete Exposure Pathways
    Comment: Multiple commenters asserted that EPA must demonstrate the 
existence of a complete exposure pathway to justify regulatory action, 
which some defined as exposures that have already occurred. 
Specifically, commenters stated that ``the presence of groundwater 
contamination alone does not constitute a risk'' and ``in many cases no 
one is drinking the water or contacting the CCR materials.'' One 
commenter presented a summary of analyses that had been conducted 
across 27 sites, which concluded that groundwater risks do not exist at 
most sites because no drinking water wells are currently present. 
Another commenter asserted that the high-end risks identified in the 
2014 Risk Assessment assumed that receptors were exposed immediately 
downgradient of the disposal units. This commenter went on to state 
that complete exposures would not occur at the many sites adjacent to 
water bodies because groundwater contamination would be intercepted by 
surface water first and that the 2014 Risk Assessment found no risks 
warranting regulation for surface water. Several other commenters also 
claimed that groundwater quality should be measured at the facility 
boundary because that would be more representative of a complete 
exposure pathway.
    EPA Response: Section 4004(a) of RCRA requires EPA to establish 
requirements that will ensure no reasonable probability of adverse 
effects both to human health and the environment. See, 42 U.S.C. 
6944(a). EPA therefore disagrees that only the presence of receptors 
within the impact sphere of a contaminating facility merits 
consideration. EPA's longstanding and consistent policy (across 
numerous regulatory programs) has been that groundwater contamination 
is a significant concern that merits regulatory action in its own 
right, whether or not the aquifer is not currently used as a source of 
drinking water.
    Once a potentially harmful constituent has leached from a disposal 
unit into groundwater, whether the constituent ultimately causes 
further damage by migrating into drinking water wells does not diminish 
the significance of the environmental damage caused to the groundwater 
under the site, even where it is only a potential future source of 
drinking water. As EPA explained in the preamble to the original 1979 
subtitle D criteria, EPA is concerned with groundwater contamination 
even if the aquifer is not currently used as a source of drinking 
water. Sources of drinking water are finite, and future users' 
interests must also be protected. See, 44 FR 53445-53448. (``The Act 
and its legislative history clearly reflect Congressional intent that 
protection of groundwater is to be a prime concern of the criterion. . 
. . EPA believes that solid waste activities should not be allowed to 
contaminate underground drinking water sources to exceed established 
drinking water standards. Future users of the aquifer will not be 
protected unless such an approach is taken.''). See also, 80 FR 21453.
    The commenters' approach is also inconsistent with Agency guidance, 
which states that a ``. . . pathway is complete if there is (1) a 
source or chemical release from a source, (2) an exposure point where 
contact can occur, and (3) an exposure route by which contact can 
occur.'' \30\ The guidance goes on to state that ``. . . exposure 
assessments are concerned with current and future exposures.'' Thus, a 
key consideration in evaluating risk is the potential for future 
exposure. If it were necessary to wait for exposures to occur as a 
prerequisite for action, an untold number of receptors could be subject 
to potential harm. Further, implementation of corrective action is not 
instantaneous and so this harm could persist for some time after 
receptor exposures are first identified. Commenters do not explain how 
such delayed action could be considered protective of human health and 
the environment, and so meet RCRA's standard. See, USWAG, 901 F3d at 
429-431.
---------------------------------------------------------------------------

    \30\ U.S. EPA. 1989. ``Risk Assessment Guidance for Superfund 
Volume I: Human Health Evaluation Manual (Part A).'' EPA/540/1-89/
002. Prepared by the Office of Emergency and Remedial Response. 
Washington, DC. December.
---------------------------------------------------------------------------

    Commenters also misrepresent the findings of the 2014 Risk 
Assessment regarding surface water interception. EPA modeled a 
distribution of distances for both groundwater wells and surface water 
bodies, accounting for interception whenever a water body was located 
closer than a well. Thus, reported high-end risks do not include any 
assumptions about the proximity of receptors to the units. Even if 
direct exposure to groundwater from use as a drinking water source is 
considered unlikely due to the potential for interception by nearby 
surface water, that does not justify no further action. EPA did 
identify the potential risks from individual disposal units to 
ecological receptors present in these water bodies and human receptors 
who fish from those water bodies, as well as associated damage cases, 
which is why constituents, such as cadmium and mercury, were added to 
the Appendix IV list of constituents. Additionally, surface water 
bodies are large and highly interconnected systems that are likely to 
have multiple electric utilities, as well any number of other 
industrial sources, located along their banks. If all these facilities 
were allowed to freely discharge to a water body solely because no 
individual release posed risk, the cumulative impacts can result in 
risk to surface water resources and nearby receptors. The 2015 CCR Rule 
addresses the potential for such risk by specifying corrective action 
must ``remove from the environment as much of the contaminated material 
that was released from the CCR unit as is feasible.'' 40 CFR 
257.97(b)(3). Thus, dilution of a groundwater plume into surface water 
could not be considered a presumptive remedy. This requirement is 
consistent with guidance for OLEM programs that specify the need to 
prevent groundwater contamination above GWPS from contaminating other 
aquifers or environmental media.\31\
---------------------------------------------------------------------------

    \31\ U.S. EPA. 2009. ``Summary of Key Existing EPA CERCLA 
Policies for Groundwater Restoration.'' OSWER Directive 9283.1-33. 
Prepared by the Office of Solid Waste and Emergency Response. 
Washington, DC. June.
---------------------------------------------------------------------------

    EPA also disagrees that a point of compliance at the facility 
boundary would provide a better estimate of actual risk than the waste 
boundary. Again, the commenter disregards that the contamination of the 
aquifer is an adverse effect on the environment, not simply a potential 
risk to subsequent receptors. Consequently, the regulations require 
facilities to address the contamination at the first available point, 
that is, when it first leaves the unit. There are several additional 
reasons that the waste boundary is the appropriate point of compliance. 
First, a point of compliance at the facility boundary would result in 
greater potential for current residences or water bodies immediately 
adjacent to the facility boundary to be exposed before the presence of 
contamination can be confirmed. Second, the facility boundary may be a 
significant distance away from the waste boundary, which would allow 
contamination to increase and spread for some time before triggering 
corrective action. The further contamination is allowed to increase and 
spread, the more difficult it may become to clean it up due to factors 
such as complex contaminant chemistry and site hydrogeology. This may 
render

[[Page 38974]]

large volumes of groundwater unusable for drinking water or other 
purposes. Finally, EPA has previously documented numerous instances 
where, once the contaminant plume has migrated off-site and impacted 
private water wells, a utility has purchased these properties, thereby 
rendering the off-site contamination, ``on-site,'' further delaying 
corrective action. See, 80 FR 21456. For all these reasons, EPA 
considers the waste boundary to provide the most consistent and 
protective basis on which to establish evidence of a release.
4. 2024 Final Risk Assessment
    EPA identified risks to groundwater from active CCR landfills and 
surface impoundments, as well as to inactive CCR surface impoundments 
at active utilities in the 2014 Risk Assessment, which are now 
regulated under the 2015 CCR Rule. The results of EPA's further 
analyses in the final 2024 Supplemental Risk Analysis confirm that the 
findings on the risk from active units from the 2014 Risk Assessment 
are equally applicable to units that ceased receipt of waste prior to 
2015 and either closed or became inactive. This final rule therefore 
relies upon the 2014 Risk Assessment, the additional data and analysis 
presented in the March 2023 proposal indicating that the legacy CCR 
surface impoundments and CCRMU would be expected to have risks even 
higher than previously modeled, and the 2024 Supplemental Risk 
Assessment. Each of these is discussed in turn below.
a. Summary of 2014 Risk Record
    In the 2014 Risk Assessment EPA conducted a national-scale, 
probabilistic analysis that characterized potential risks to human and 
ecological receptors associated with leakage from CCR surface 
impoundments and landfills in operation at that time. A combination of 
models was used to predict fate and transport of contaminants through 
the environment, receptor exposures, and the resulting risks to human 
and ecological receptors. The specific exposure routes evaluated were: 
(1) Human inhalation of particulate matter blown from open management 
units, (2) Human ingestion of crops and livestock raised on nearby 
fields, (3) Human ingestion of groundwater used as a source of drinking 
water, (4) Human ingestion of fish caught from freshwater streams, and 
(5) Ecological contact with and ingestion of surface water and 
sediment. Site-specific data were used where available, supplemented by 
regional and national data to fill data gaps, to capture the 
variability of waste management practices, environmental conditions, 
and receptor behavior. EPA reported risks for both highly exposed 
individuals and more moderately exposed individuals. Risks to highly 
exposed individuals represent a reasonable maximum estimate that 
members of the general population might be exposed to, which were 
calculated as the 90th percentiles of all probabilistic model results. 
Risks to moderately exposed individuals represent a more typical 
estimate that members of the general population might be exposed to, 
which were calculated as the 50th percentiles of all probabilistic 
model results.
    Under RCRA, EPA typically relies on a risk range to determine the 
point at which regulation is appropriate. This policy was first 
developed in the context of determining whether to regulate (or 
``list'') wastes as hazardous under subtitle C of RCRA. See 80 FR 
21449; 59 FR 66075-66077, December 22, 1994. However, over the years 
EPA has relied on this risk range more broadly to determine whether 
regulation is warranted under both subtitles C and D of RCRA. See 75 FR 
35193 (``Although the statutory standards under subsections C and D 
differ, EPA has historically interpreted both statutory provisions to 
establish a comparable level of protection, corresponding to an 
acceptable risk level ranging between 1 x 10-\4\ and 1 x 
10-\6\.'').
    Thus, to determine whether there is a reasonable probability of 
adverse effects on health or the environment from the disposal or other 
solid waste management of solid waste, EPA typically uses as an initial 
cancer risk ``level of concern'' a calculated risk level of 1 x 
10-\5\ (one in one hundred thousand) or an HQ above 1.0 for 
any noncarcinogenic risks. See, 80 FR 21,449. For example, wastestreams 
or activities for which the calculated high end individual cancer-risk 
level is 1 x 10-\5\ or higher generally are considered 
candidates for regulation. Wastestreams or activities with risks 
calculated to be 1 x 10-\4\ (one in ten thousand) or higher 
generally will be considered to pose a reasonable probability of 
adverse effects on health or the environment and generally will be 
regulated. Wastestreams or activities for which these risks are 
calculated to be 1 x 10-\6\ (one in one million) or lower, 
and lower than 1.0 HQ or environmental risk quotients for any 
noncarcinogens, generally will be considered not to pose a reasonable 
probability of adverse effects on health or the environment, and 
generally will not be regulated. Id.
    EPA first evaluated national-scale risks in the 2014 Risk 
Assessment, which provides a snapshot in time of potential risks across 
the country. This was accomplished by weighting risks from individual 
management practices in proportion to the anticipated prevalence of 
those practices. National-scale risks provide important context as to 
whether risks are a systemic issue that warrant national regulations or 
are limited in scope and better addressed through more targeted 
actions. The Agency's evaluation found that the management practices 
that EPA believed were generally in use in 2014 at surface impoundments 
and landfills were likely to pose risks to human health through 
groundwater exposure within the range that EPA typically considers 
warrants regulation. For highly exposed individuals, the cancer risks 
from arsenic due to the operation of surface impoundments were as high 
as 2 x 10-\4\, while noncancer risks were as high as an HQ 
of 5 for arsenic, 2 for lithium, and 2 for molybdenum. Cancer risks 
associated with the operation of landfills were estimated to be as high 
as 5 x 10-\6\ from the ingestion of arsenic-contaminated 
drinking water. In contrast, all risks for moderately exposed 
individuals fell below EPA's risk range. This was largely attributed to 
the fact that many facilities are located next to major water bodies 
and so contaminant plumes were frequently intercepted by these water 
bodies before they could reach private wells.
    EPA next evaluated the risks associated with individual management 
practices at surface impoundments and landfills. This was accomplished 
by filtering the national-scale model runs to focus only on those that 
included the practice of interest and using the filtered set of runs to 
calculate risks associated with that specific practice. These 
individual risks provide important context about the range of 
contaminants and practices that could pose risk at individual sites. 
The Agency's evaluation identified two specific management practices 
that could lead to risks higher than those identified in the national 
risk estimates.
    The first practice EPA evaluated was the disposal of CCR in unlined 
and clay-lined units. Management in unlined surface impoundments 
resulted in cancer risks for arsenic up to 3 x 10-\4\, as 
well as noncancer risks for lithium up to an HQ of 3, molybdenum up to 
an HQ of 4, and thallium up to an HQ of 2. Management in unlined 
landfills resulted in cancer risks for arsenic up to 2 x 
10-\5\. The larger increase in arsenic risks identified for 
unlined landfills above those for national-scale landfills (2 x 
10-\5\ vs. 5 x 10-\6\) compared to unlined and 
national-scale

[[Page 38975]]

impoundments (3 x 10-\4\ vs. 2 x 10-\4\) is 
because a larger proportion of landfills nationwide were initially 
modeled as having a liner. Since promulgation of the 2015 CCR Rule, it 
has become clear that more units are unlined than originally estimated. 
Thus, it is anticipated that national-scale risks for landfills would 
actually be closer to those for unlined landfills (2 x 
10-\5\), rather than the lower nation-wide estimates 
reported in the 2014 Risk Assessment.
    Although clay-lined units tended to have lower risks than unlined 
units, they still had potential to result in risks within the range 
that EPA considers for regulation under RCRA. Management in clay-lined 
impoundments with a liner thickness of three feet resulted in cancer 
risks for arsenic of up to 7 x 10-\6\ and noncancer risks 
for lithium up to an HQ of 2, while management in similarly unlined 
landfills resulted in cancer risks for arsenic up to the 1 x 
10-\5\. The larger increase in arsenic risks for unlined 
impoundments above those for clay-lined impoundments (1 x 
10-\5\ vs. 7 x 10-\6\) compared to unlined and 
clay-lined landfills (2 x 10-\5\ vs. 1 x 10-\5\) 
is because the layer of low conductivity clay counteracts the hydraulic 
head in impoundments that would otherwise freely drive greater volumes 
of leachate into the subsurface.\32\ In contrast, leachate generation 
in both types of landfills is limited far more by the rate of 
precipitation. As a result, EPA further considered how reducing the 
modeled clay liner thickness of impoundments to the minimum allowable 
standard of two feet would affect arsenic risk and found it would 
increase to as high as 2 x 10-\5\.
---------------------------------------------------------------------------

    \32\ The somewhat higher risks identified for clay-lined 
landfills compared to similarly lined impoundments are likely 
related to site-specific conditions, such as where in the country 
these units are located.
---------------------------------------------------------------------------

    The second practice evaluated was the management of wastes with an 
extreme pH. In particular, empirical porewater data revealed that co-
disposal of CCR with other wastes in surface impoundments had the 
potential to result in a highly acidic pH, cancer risks for arsenic up 
to 1 x 10-\3\, and noncancer risks for cobalt and mercury up 
to an HQ of 13 and 5, respectively. Laboratory leaching test data also 
indicated that highly acidic and basic CCR wastes have the potential to 
leach similarly high arsenic concentrations, up to an order of 
magnitude higher than under more neutral conditions. Only a small 
number of previous landfill model runs considered acidic conditions 
based on the information available about conditions in active units; 
identified risks for these units were driven by more basic conditions. 
Thus, to the extent that conditions at either extreme of the pH scale 
are more prevalent than previously estimated, it is likely that overall 
risks from disposal in both surface impoundments and landfills would be 
even higher than modeled.
    EPA acknowledged in the 2014 Risk Assessment that there were some 
additional management practices that could result in higher risk at 
individual sites, but that could not be quantitatively modeled with the 
data available at the time. One specific example provided was of CCR 
disposal below the water table. EPA was unable to quantitatively model 
the associated risks as there was little data on how common this 
practice was or the extent to which it could affect groundwater 
chemistry. Because EPA could not quantitatively model these management 
practices (and because the Agency had no information to indicate that 
it was a current, widespread management practice), EPA noted only that, 
based on its review of damage cases, the damage from the placement of 
CCR in sand and gravel pits was almost always associated with CCR being 
placed in contact with water, which indicated that the placement of CCR 
in contact with water can lead to higher risks than from dry disposal. 
80 FR 21352. EPA further explained that ``in this situation, the 
sorption that occurs in the unsaturated zone of the risk assessment 
model does not occur in the field. This and other site-specific risk 
factors could lead to additional contamination beyond what was modeled 
nationwide.'' 2014 Risk Assessment at pages 5-48. As a consequence, EPA 
specifically included sand and gravel pits that received CCR in the 
definition of CCR landfills covered by the regulations. 80 FR 21354.
    The above model results from the 2014 Risk Assessment are equally 
applicable to legacy CCR surface impoundments and CCRMU. Many of these 
unregulated units are similarly constructed, manage the same types of 
ash, and are frequently located either at the same or nearby facilities 
as their regulated counterparts. In particular, some unregulated units 
are known to be located directly adjacent to or beneath currently 
regulated units. The fact that some of these unregulated units no 
longer contain water ponded above the ash surface or have installed 
some form of cover system does not meaningfully distinguish the long-
term risks of these units from those previously modeled. This is 
because all landfills and surface impoundments progress through similar 
lifecycle stages. Progression toward closure does not remediate any 
releases that occurred during operation of the unit. Furthermore, if a 
unit is not closed with an effective cover system or remains in contact 
with the groundwater table, the higher rates of leakage that can result 
could sustain releases long after the unit has ceased operation. It is 
expected that legacy impoundments and CCRMU have been present for 
longer than currently operating units and so would have had more time 
to leak. As a result, previous and ongoing releases from these units 
have the potential to be greater and to have migrated further than 
those from the currently regulated universe of units.
    The risks associated with legacy impoundments and CCRMU may be even 
higher than EPA modeled on a national scale in the 2014 Risk 
Assessment. The 2014 Risk Assessment aimed to provide a static snapshot 
of waste management practices at that time based on the available data. 
As such, it did not reflect the greater prevalence of some practices at 
older closed and inactive units based on the understanding those 
practices had declined over time. Nor did it reflect some ongoing 
practices for which there was not enough data to characterize 
prevalence on a national scale. The Agency is now aware of several 
practices that are more common than were modeled in 2014 and have the 
potential to result in higher leakage. However, because the 2014 Risk 
Assessment identified baseline risks that warrant regulation, the 
national risk record does not depend on the greater prevalence of these 
practices to justify the need for regulation of closed and inactive 
units. Instead, the potential for even higher risk from these practices 
at individual units, which are discussed below, only reinforces the 
basis for regulation.
    First, a greater number of units lack an adequate liner system than 
EPA previously understood. For example, in the 2014 Risk Assessment, 
EPA estimated that 65% of impoundments had no engineered liner (i.e., 
do not meet the regulatory standard for either a clay or composite 
liner) based on surveys conducted by EPA between 2009 and 2010 (``EPA 
Surveys'').\33\ It has since become clear that even fewer impoundments 
are actually lined. EPA's review of available liner demonstration 
documents posted on facilities' CCR websites indicates closer to 83% of 
impoundments have no engineered liner. Similar reporting is not 
available

[[Page 38976]]

on the liner prevalence for older units. However, EPA is also not aware 
of any evidence that these older units have been lined at higher rates, 
particularly those constructed prior to the promulgation of minimum 
standards for disposal in RCRA subtitle D landfills in 1991. See, 40 
CFR part 257, subpart A and part 258. Indeed, most coal-fired utilities 
in the United States were constructed before 1990.\34\ Even when units 
do report having an engineered liner, they may not perform as well as 
previously modeled. The 2014 Risk Assessment modeled both clay and 
composite liners based on the presumption both would achieve regulatory 
performance standards. Yet, facility reports show that around 10% of 
landfills and surface impoundments with a composite liner have already 
entered into corrective action. Thus, many units previously modeled as 
lined are now believed to either have no engineered liner or to perform 
more like an unlined unit. For these reasons, EPA anticipates that 
national risks for both currently regulated units and those newly 
covered under this rulemaking will be closer to those previously 
modeled for unlined units. For landfills, this could increase national 
risks by up to an order of magnitude, as high as 2 x 10-\5\ 
for arsenic. That risk is twice the level that EPA typically considers 
for regulation and is the same level of risk as those associated with 
the clay-lined CCR surface impoundments that the D.C. Circuit required 
to close.
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    \33\ U.S. EPA. 2014. ``Human and Ecological Risk Assessment of 
Coal Combustion Residuals.'' RIN 2050-AE81. Office of Solid Waste 
and Emergency Response. Washington, DC. December.
    \34\ United States Energy Information Administration. 2017. 
``Most Coal Plants in the United States were Built Before 1990.'' 
Accessed online at: https://www.eia.gov/todayinenergy/detail.php?id=30812.
---------------------------------------------------------------------------

    Second, a greater number of older units co-disposed CCR with the 
wastes generated from coal preparation activities, collectively 
referred to as ``coal refuse.'' These activities may have included coal 
handling by conveyor systems, coal washing for removing mineral matter, 
and coal ``sizing'' to reduce the average particle size of coal. Co-
disposal with coal refuse can have a pronounced effect on the leaching 
behavior of CCR because of the potential for the refuse to make the 
overall waste pH far more acidic. Available Leaching Environmental 
Assessment Framework (LEAF) leaching data considered in the 2014 Risk 
Assessment show that multiple Appendix IV constituents are most soluble 
under extreme pH conditions and thus able to leak at higher rates. EPA 
found modeled risks are highest when CCR was disposed in surface 
impoundments with coal refuse. The modeled cancer risks for the co-
disposal of ash and coal refuse in surface impoundments ranged between 
1 x 10-\3\ for trivalent arsenic to 4 x 10-\4\ 
for pentavalent arsenic. Non-cancer risks were similarly high, ranging 
between and an HQ of 13 for cobalt and HQ of 14 for pentavalent arsenic 
to 26 for trivalent arsenic, based on the ingestion of contaminated 
drinking water.
    The practice of co-disposal with coal refuse has declined over 
time. A survey conducted by Electric Power Research Institute (EPRI) in 
1995 showed 34% of unlined landfills and 68% of unlined surface 
impoundments actively managed CCR with coal refuse.\35\ In contrast, 
EPA Surveys indicated that, by 2014 this management practice had 
declined to around 5% of active units. EPA's 2014 national-scale 
modeling was based on the 5% reported in the EPA Surveys, and as a 
consequence, this practice had minimal influence on the overall 
nationwide risk estimates in the 2014 Risk Assessment. However, it is 
clear from the EPRI data that management of CCR with coal refuse used 
to be far more common prior to 1995. Of the 283 disposal units that 
were previously excluded from the 2014 Risk Assessment and that 
reported a start year in the EPA Surveys, around 91% had already begun 
operation by 1995. Therefore, the risks associated with these older 
disposal units are likely to be higher than the national scale risks 
reported in the 2014 Risk Assessment.
---------------------------------------------------------------------------

    \35\ EPRI. 1997. ``Coal Combustion By-Products and Low-Volume 
Wastes Comanagement Survey.'' Palo Alto, CA. June.
---------------------------------------------------------------------------

    Finally, it has become apparent since promulgation of the 2015 CCR 
Rule that the practice of disposing of CCR below the water table is 
more common than EPA previously understood. EPA was aware of this 
practice in 2014 and raised it as an uncertainty in the risk 
assessment, but had little information about the frequency of this 
practice. EPA's review of the location restriction demonstrations 
posted on facilities' CCR websites found that approximately 31% of 
active CCR surface impoundments had waste below the water table. 
Similar statistics are not currently available for landfills, though it 
is clear from previously identified damage cases that this practice is 
not unique to impoundments. Nor is EPA aware of any evidence that would 
indicate older units are less likely on the whole to have been 
constructed within the water table. EPA was unable to model the effects 
of disposal in the water table in 2014 due to constraints on data 
availability and modeling capabilities.
    Disposal beneath the water table, either continuously or 
intermittently, will result in conditions that mirror those previously 
found to drive risk from active surface impoundments. Specifically, 
saturation of disposed CCR provides a larger reservoir of leachate and 
the hydraulic gradient across the aquifer maintains a hydraulic head 
that serves to drive this leachate away from the unit. The implications 
for landfills are particularly significant, as the potential for 
greater contaminant transport from these units can result in higher 
risks to groundwater than previously modeled under dry conditions. 
Further, because these landfills leak directly to groundwater, there is 
potential for these risks to remain long after the unit has ceased 
operation. This is equally true for impoundments. Even if the hydraulic 
head within the aquifer is not as great as from ponded water, it can 
still sustain higher rates of leakage than if the unit were fully 
dewatered. As a result, removal of the saturated ash may be the only 
reliable means to control the source of contamination.
    Since promulgation of the 2015 CCR Rule, EPA has identified 
evidence of another way in which disposal below the water table could 
result in greater risk. This disposal practice has the potential to 
alter groundwater chemistry in ways that increase either the solubility 
or mobility of some CCR contaminants. This is due to the residual, 
unburnt organic matter in CCR serving as a carbon source (i.e., 
substrate, electron donor) for bacteria in the soil. Bacteria 
preferentially use any dissolved oxygen (O2) for oxidation 
of organic matter (i.e., electron transfer from the organic matter to 
oxygen) because this yields the greatest energy returns for the 
bacteria. With a sufficient source of biodegradable organic matter, 
bacterial consumption of oxygen can outpace replenishment of dissolved 
oxygen that occurs through diffusion from the atmosphere and 
infiltration of precipitation. Depletion of oxygen is more likely to 
occur in saturated soils because the constant presence of water allows 
biological activity to proceed unimpeded by periods of drying, the 
relatively slow flow rate of groundwater does not transport dissolved 
oxygen from the upgradient side of the unit fast enough to outpace 
consumption across the footprint of the unit, and sustained saturation 
of the soil limits oxygen exchange with the atmosphere. In the absence 
of oxygen, bacteria will instead use nitrate, manganese, iron, sulfate, 
and other compounds for reduction of organic matter (i.e., electron 
transfer to

[[Page 38977]]

organic matter from other compounds). Such reducing conditions will not 
affect all constituents equally, serving to mobilize some and 
immobilize others. However, reducing conditions can mobilize arsenic, 
the primary source of risks identified in the 2014 Risk Assessment.
    Research conducted since the 2014 Risk Assessment has better 
documented the potential effects of disposal below the water table on 
leakage from CCR units. Studies published in 2022 examined, among other 
things, the degree to which environmental conditions can differ within 
the same closed impoundment, both above and below the water 
table.36 37 Specifically, arsenic concentrations measured in 
the water intermingled with CCR beneath the water table were as high as 
4,100 mg/L due to the presence of reducing conditions and a near 
neutral pH of 8. That concentration is substantially higher than 20 mg/
L, measured from the same ash with LEAF Method 1313 at a similar pH, or 
780 mg/L, which is the 90th percentile of all impoundment porewater 
measurements previously compiled by EPA. This indicates that the 
porewater and LEAF data relied on the 2014 Risk Assessment may 
significantly underestimate the magnitude of leakage from CCR units 
under reducing conditions.
---------------------------------------------------------------------------

    \36\ Wang, X., A.C. Garrabrants, Z. Chen, H.A. van der Sloot, 
K.G. Brown, Q. Qiu, R.C. Delapp, B. Hensel, and D.S. Kosson. 2022. 
``The Influence of Redox Conditions on Aqueous-Solid Partitioning of 
Arsenic and Selenium in a Closed Coal Ash Impoundment.'' Journal of 
Hazardous Materials. 428:128255.
    \37\ Wang, X, H.A. van der Sloot, K.G. Brown, A.C. Garrabrants, 
Z. Chen, B. Hensel, and D.S. Kosson. 2022. ``Application and 
Uncertainty of a Geochemical Speciation Model for Predicting 
Oxyanion Leaching from Coal Fly Ash under Different Controlling 
Mechanisms.'' Journal of Hazardous Materials. 438:129518.
---------------------------------------------------------------------------

    The extent to which the porewater data EPA used to model surface 
impoundments in 2014 reflect strong reducing conditions is not known, 
as this information was not commonly reported. Such conditions might 
occur during operation as a result of sustained saturation or might 
evolve after an impoundment has been drained of ponded water and 
capped, thereby decreasing mixing of oxygen within the unit. However, 
it is known that the LEAF data used to model landfills does not reflect 
reducing conditions. All standardized leaching tests tend to reflect 
oxidizing conditions due to contact between the sample and the 
atmosphere during sample collection and laboratory analysis. As such, 
it has since been recognized that further analysis of leachate data 
with geochemical speciation models may be warranted when field 
conditions diverge from those present in the laboratory setting (e.g., 
reducing conditions).\38\ Therefore, there is clear potential for 
significantly higher leachate concentrations than modeled if a landfill 
is in contact with groundwater.
---------------------------------------------------------------------------

    \38\ U.S. EPA. 2019. ``Leaching Environmental Assessment 
Framework (LEAF) How-To Guide: Understanding the LEAF Approach and 
How and When to Use It.'' Office of Land and Emergency Management. 
Washington, DC. May.
---------------------------------------------------------------------------

b. 2024 Risk Assessment and Results
    As noted above, a number of commenters argued the 2014 Risk 
Assessment does not adequately capture various factors associated with 
legacy impoundments and CCRMU that the commenters believe will result 
in significantly different risks than those posed by currently 
regulated units. In response, EPA prepared a supplemental risk 
assessment to determine the potential for some of these factors to 
affect national risks (``2023 Draft Risk Assessment''). EPA began by 
reviewing available information about the characteristics and locations 
of legacy impoundments and CCRMU to determine whether there was any 
potential for the risks from these units to be meaningfully different 
from currently regulated units. This included a review of groundwater 
model results previously excluded from the 2014 Risk Assessment because 
the units were ultimately not covered by the 2015 CCR Rule.
    As part of this review, EPA grouped legacy impoundments and CCRMU 
disposal units into different categories based on unit type: (1) 
Historical and inactive landfills and (2) Historical and legacy 
impoundments. The 2024 Risk Assessment defines historical units as 
those that have steps taken toward closure, but that may or may not 
meet all the requirements of Sec.  257.102(d). Additionally, EPA 
further considered the influence of unit size on risk and conducted 
additional modeling for the subset of CCRMU that is smallest in size, 
those used as fill or for similar purposes (hereafter ``CCRMU fills''). 
Because facilities have not historically regarded such placement as 
disposal units or necessarily maintained associated records, EPA 
believes there is potential for exposures different than those 
previously considered for landfills and surface impoundments. 
Specifically, EPA evaluated the potential for risk from onsite exposure 
to contaminated groundwater or CCR accumulations in the soil under a 
future residential land use scenario.
i. Problem Formulation
    EPA first developed conceptual models to illustrate a generalized 
layout of legacy impoundments and CCRMU, the different pathways through 
which constituents may be released from CCR and migrate through the 
environment, and the risks to human health and the environment that 
could result. The conceptual models for landfills and impoundments were 
the same as used in the 2014 Risk Assessment/EPA determined that a 
second model was warranted for CCRMU because some smaller placements 
have not historically been regarded as disposal by facilities and so 
have not been reliably tracked or maintained over time. These smaller 
placements may be disturbed after land use changes, which can result in 
additional release pathways. Therefore, EPA prepared a second 
conceptual model for smaller units (i.e., CCRMU fills). These 
conceptual models provide the basis for subsequent modeling efforts.
    When CCR are placed on the ground for any purpose, they may leach 
metals and other inorganic contaminants to groundwater. Once mixed with 
groundwater, contamination may migrate downgradient to private wells 
where it is ingested by receptors who rely on groundwater as their 
primary source of drinking water. But a receptor does not need to be 
presently exposed for there to be a reasonable probability of adverse 
effects on health or the environment. EPA evaluated this exposure 
pathway in the 2014 Risk Assessment and identified a set of 
constituents most likely to pose risk to offsite receptors living up to 
a mile away. The 2024 assessment builds on those model results and 
identifies arsenic, lithium, molybdenum, and thallium as constituents 
that warranted further evaluation. These are the constituents found in 
the 2014 Risk Assessment to pose the greatest risk for unlined surface 
impoundments and have the greatest demonstrated potential to spread and 
pose risk on a national scale. These 2014 model results therefore also 
provide a reasonable screen to identify the most likely risk drivers 
for receptors living even closer to these types of units.
    When CCR is placed in fills and left unmonitored, the ash can be 
disturbed in the future when land use changes. In the absence of 
records of the presence of CCR, and in the absence of inspection and 
maintenance, any engineering controls currently present that might 
serve to limit exposure cannot reasonably be assumed to remain in place 
in perpetuity. For this reason, EPA

[[Page 38978]]

considered the potential for additional exposure pathways that could 
occur under a future residential land use scenario. The 2014 Risk 
Assessment did not evaluate risks from direct placement of CCR in the 
soil. However, EPA previously identified radium as a constituent of 
concern in the 2015 CCR Rule and included two radioisotopes on the 
Appendix IV list for groundwater monitoring, radium-226 and radium-228. 
These radioisotopes are part of larger, naturally occurring decay 
chains that begin with uranium-238 and thorium-232, respectively. Even 
if some form of cover remains over the ash, future receptors who live 
on or around a fill may be exposed to radiation through direct exposure 
to gamma radiation or inhalation of radon gas. Therefore, EPA 
considered potential for exposure to the full decay chains of these 
radium isotopes as the primary risk driver for this pathway.
ii. Disposal Unit Groundwater Risk
    All disposal units pass through the same lifecycle stages, ranging 
from initial construction to final closure. As a result, there is 
potential for historical and inactive disposal units to result in the 
same types of environmental releases as currently regulated units over 
the course of their lifecycle. The fact some historical and inactive 
units may have since drained ponded wastewater or installed some form 
of cover system does nothing to remediate any prior releases. EPA 
conducted a review of the available data on these historical and 
inactive units to understand whether the associated risks would be 
expected to differ from those previously modeled for regulated units.
    The 2014 Risk Assessment modeled risks for a total of 122 landfills 
and 163 impoundments that were ultimately excluded from the final 
summary of national risks because it was determined that these units 
fell outside the scope of the 2015 CCR Rule. These units were excluded 
because they were anticipated to cease receipt of waste prior to the 
effective date of the rule. Therefore, model results for these 
previously excluded units directly address the historical and inactive 
units subject to the current rulemaking. EPA reviewed model results for 
these previously excluded units to better understand whether the 
associated risks were any different from those of currently regulated 
units. For highly exposed individuals, landfills were estimated to pose 
cancer risks as high as 7 x 10-\6\ from arsenic III, while 
surface impoundments were estimated to pose cancer risks as high as 8 x 
10-\5\ from arsenic III and noncancer HQs as high as 2 for 
arsenic III, 2 for lithium, and 1 for molybdenum.
    Differences between these risks and those for currently regulated 
units are attributed primarily to differences in the prevalence of 
engineered liners modeled for the two sets of units. The previously 
excluded units were modeled as having no engineered liner at 71% of 
landfills and 57% of impoundments, compared to 42% of landfills and 65% 
of impoundments for currently regulated units. For unlined units, the 
arsenic III risk from previously excluded units was 1 x 
10-\5\ for landfills and 2 x 10-\4\ for surface 
impoundments, while corresponding risk from regulated units were 2 x 
10-\5\ for landfills and 3 x 10-\4\ for surface 
impoundments. Since all of this modeling was completed in 2014, it has 
been discovered through facility reporting that a greater percentage of 
regulated units has no engineered liner than EPA previously modeled. 
For example, in the 2014 Risk Assessment, EPA estimated that 65% of 
impoundments had no engineered liner based on the EPA Surveys.\39\ It 
has since become clear that even fewer impoundments are actually lined. 
EPA's review of available liner demonstration documents posted on 
facilities' CCR websites indicates closer to 83% of have no engineered 
liner. EPA has seen no evidence that would indicate older historical 
and inactive units would be lined at any greater frequency. Thus, EPA 
concludes that the national risks for regulated and previously excluded 
units will fall closer to those modeled for unlined units.
---------------------------------------------------------------------------

    \39\ U.S. EPA. 2014. ``Human and Ecological Risk Assessment of 
Coal Combustion Residuals.'' RIN 2050-AE81. Office of Solid Waste 
and Emergency Response. Washington, DC. December.
---------------------------------------------------------------------------

    EPA reviewed available data on facility location to understand 
whether environmental conditions (e.g., precipitation, soil type) at 
inactive and active facilities could be substantially different than 
previously modeled. Such conditions can affect the rate of leakage from 
a unit and subsequent transport of that leachate through the 
subsurface. This review found that around 80% of the active and 
inactive facilities that were not subject to the 2015 CCR Rule had 
already been modeled as part of the 2014 Risk Assessment and so are 
already reflected in the risk results for those previously excluded 
units. The remaining 20% of facilities are located an average distance 
of 26 miles from the nearest modeled facility. Therefore, EPA concludes 
that the 2014 Risk Assessment adequately captures the effects of 
facility location on national risk.
    Commenters stated that the smaller size of historical and inactive 
disposal units would result in lower volumes of leakage and could not 
sustain plumes of the same magnitude as from larger regulated units. 
EPA reviewed data from the EPA Surveys to determine whether the sizes 
of previously excluded units are substantially different than EPA 
modeled for currently regulated units. This comparison indicates that 
excluded units do tend to be somewhat smaller. The average size modeled 
for excluded units was 77 acres for landfills and 28 acres for 
impoundments. The average size modeled for regulated units was 107 
acres for landfills and 47 acres for impoundments. Despite these 
differences, there remains a great deal of overlap in the range of 
sizes for both sets of units. Further, as described above, similar 
risks were identified for both sets of units. Thus, there is no 
indication that size differences of this magnitude have any notable 
effect on national risk. Nor is there any information available about 
the units not captured in the EPA Surveys that would indicate these 
remaining units are significantly smaller. Therefore, EPA concludes 
that the 2014 Risk Assessment adequately captures the effects of unit 
size on national risk.
iii. CCRMU Fill Groundwater Risk
    EPA conducted national-scale modeling of CCRMU fills to understand 
the potential groundwater risks that could result from these smaller 
placements of CCR. The exposure route evaluated for was human ingestion 
of groundwater used as a source of drinking water. The evaluation 
incorporated many of the same data sources used in the 2014 Risk 
Assessment to characterize the variability of site conditions. Two 
models were used to evaluate contaminant fate and transport, EPACMTP 
and MODFLOW-USG. EPACMTP was run first at specified distances along the 
centerline of the plume to understand the potential for releases to 
occur and spread further downgradient. MODFLOW-USG was then run for a 
subset of the conditions to understand the broader magnitude and extent 
of these plumes.
    Groundwater concentrations modeled with EPACMTP at the waste 
boundary were first compared to respective GWPS to understand the 
potential for fills to impact groundwater quality to an extent that 
would trigger corrective action at regulated landfills. The 90th 
percentile concentrations exceeded GWPS by factors of 26 for arsenic 
III, 19 for arsenic V, 156 for molybdenum, and 19 for thallium. The 
50th percentile

[[Page 38979]]

concentrations exceeded GWPS by a factor of two for molybdenum. Based 
on these results, EPA finds that CCRMU fills can meaningfully 
contribute to groundwater contamination across a facility.
    Groundwater concentrations modeled with EPACMTP at 500 and 1,000 
feet away from the waste boundary were used calculate risks to 
individual RME receptors exposed to these concentrations. The 90th 
percentile concentration of each modeled constituent exceeded at least 
one risk benchmark at 1,000 feet. This indicates potential for leakage 
from fills to spread at environmentally significant concentrations. 
However, because these model runs represent concentrations at a fixed 
location, they do not provide broader information about the magnitude 
and extent of the plume. As a result, EPA does not rely primarily on 
these results to draw direct conclusions about overall risk. Instead, 
the Agency retained a subset of these model runs for both arsenic V and 
molybdenum from around the 90th percentile concentrations modeled at 
1,000 ft. EPA selected pentavalent arsenic because it is the less 
mobile species and so provides a reasonable bounding on the high-end 
concentrations that can result for this contaminant. These runs were 
retained for further modeling with MODFLOW-USG to characterize the full 
magnitude and extent of each plume over time.
    The MODFLOW-USG runs were designed with the same inputs as 
corresponding EPAMCTP runs. Altogether, these model runs reflect a 
range of conditions that collectively resulted in high-end groundwater 
concentrations 1,000 feet from the fill. These corresponding placements 
of CCR range from around 3,500 to 70,000 tons placed over areas between 
0.15 to 2.0 acres. EPA calculated the midpoint across these runs to 
define values representative of the 90th percentile model runs. For 
arsenic V, the model identified a peak risk of 1 x 10-\4\ 
averaged over 32 million gallons (Mgal) of groundwater and a peak 
volume of 147 Mgal with an average risk of 7 x 10-\5\. The 
same leakage of arsenic V would result in a peak GWPS exceedance of 
three averaged over a plume volume of 1.2 Mgal and a peak plume volume 
of 8 Mgal with an average exceedance of 2 times GWPS. It would take 
around 2,300 years from the time of first exceedance for the plume to 
fully dissipate. For molybdenum, the peak exceedance of both risk 
benchmark and GWPS was 10 averaged over a plume volume of 27 Mgal and a 
peak plume volume of 80 Mgal with an average exceedance of 4 times 
GWPS. It would take around 100 years from the time of first exceedance 
for the plume to fully dissipate. Plumes of these size and duration 
could readily sustain exposures for typical residential receptors that 
are anticipated to use around 80 gallons of water a day for all indoor 
household needs, resulting in less than 0.8 Mgal of use over 26 years 
of exposure.
iv. CCRMU Fill Soil Risk
    EPA modeled of CCRMU fills to understand the potential risks that 
could result from CCR present in the soil. Exposure routes initially 
considered for evaluation were human inhalation of radon gas and direct 
exposure to gamma radiation emitted from the CCR. However, based on a 
preliminary review of available data, EPA determined that radon 
emanation from CCR (i.e., fraction of radon able to escape into the 
surrounding air) is generally lower than from most soils. Despite the 
higher overall activity of CCR, the resulting radon emanation from the 
ash is not distinguishable from that of most surface soils. Therefore, 
EPA did not retain exposure to radon for further consideration.
    Modeling of exposure to gamma radiation was conducted with the EPA 
PRG calculator. EPA evaluated the potential for direct exposure to 
gamma radiation from CCR under a soil cover ranging in thickness from 
60 to 20 cm (2 to 0.66 feet). EPA compared the combined activity of the 
uranium-238 and thorium-232 decay chains in the CCR to the health 
benchmarks for each cover thickness to calculate the risks that could 
result from receptors living on or near the fill. Both 90th and 50th 
percentile activities have potential to result in cancer risks at or 
above 1 x 10-\5\ with a cover of 40 cm. The 90th percentile 
activity resulted in a cancer risk of 1 x 10-\4\ with a 
cover of 20 cm. This indicated the potential for even higher risk if 
the cover were to be disturbed and the CCR brought to the ground 
surface. However, evaluation of this scenario would require additional 
assumptions about the degree of mixing, which could be a major source 
of uncertainty on a national scale. Therefore, EPA retained this 
scenario for further consideration as part of a separate sensitivity 
analysis.
v. Uncertainty and Sensitivity Analyses
    EPA reviewed the models used, as well as the data and assumptions 
input into the models, to better understand the potential sources of 
uncertainty inherent in the model results. The Agency qualitatively 
and, to the extent possible, quantitatively analyzed these sources to 
understand the potential effects each may have on modeled risks. EPA 
also conducted further sensitivity analyses to understand how the 
modeled national risks vary in response to changes in sensitive 
parameters and to evaluate the potential for risks through exposure 
pathways that could not be fully modeled on a national scale.
    The major source of uncertainty identified for the groundwater 
model is the potential for greater risk from multiple units located in 
close proximity. The EPA Surveys did not provide information on the 
relative location or orientation of different landfills and 
impoundments at any given facility and so the 2014 Risk Assessment 
modeled risks from each unit individually. However, the Agency is now 
aware of many instances where multiple units are located directly 
adjacent to one another, resulting in a larger total area over which 
leakage can occur. This could result in greater cumulative risk to 
offsite receptors than predicted based on contributions from each 
individual unit. Furthermore, there is potential for legacy 
impoundments and CCRMU (disposal units and fill) to confound 
groundwater monitoring programs when located upgradient of a regulated 
unit. Ongoing leakage from these unregulated units has the potential to 
skew the characterization of background groundwater quality. Under 
these circumstances, any leakage from a regulated unit would need to 
progress even further and faster to be distinguishable from that skewed 
background. This could delay or entirely prevent a regulated unit from 
entering into corrective action, resulting in risk to downgradient 
receptors.
    EPA conducted a sensitivity analysis to determine whether there is 
a unit size below which adverse impacts to groundwater quality are 
unlikely and monitoring is not warranted. This analysis found 
exceedances of GWPS are possible for placements below 1,000 tons. Thus, 
such placements can meaningfully contribute to groundwater 
contamination at these facilities. It was not possible to identify a 
limit much lower than this tonnage because of the few model runs 
conducted at smaller amounts. Extrapolation beyond available model runs 
could introduce a great deal of uncertainty into any specific limit 
identified. The extent to which any identified limit could shift higher 
or lower in response to further modeling around these lowest tonnages 
is not known. Therefore, the Agency could not identify a lower limit 
based on the current modeling.

[[Page 38980]]

    EPA conducted further sensitivity analyses to better characterize 
the risks to human health that may result from mixing of CCR with the 
soil. There is little data available to predict the likelihood of 
different degrees of mixing that could occur across the country. 
Instead, EPA considered the incremental contributions from CCR through 
increased mixing with soil to identify the point at which accumulation 
would raise concern. This analysis focused on radionuclides previously 
identified as potential risk drivers for soil, but also considered 
contributions from arsenic that may further contribute to cancer risk. 
The exposure pathways considered were incidental ingestion of the CCR 
and soil mixture and direct exposure to gamma radiation. For 
radionuclides, cancer risks above 1 x 10-4 are possible for 
residential receptors at mixing of more than 11% for 90th percentile 
activity and 21% for 50th percentile activity. For arsenic, cancer 
risks above 1 x 10-4 are possible at mixing of more than 33% 
for 90th percentile concentration, but would not occur at any degree of 
mixing for 50th percentile concentration. Both radionuclides and 
arsenic also occur naturally in soil; however, levels in CCR can be 
markedly higher than typical background levels. In particular, EPA has 
identified the potential for CCR to have a combined radium activity 
nearly 10 pCi/g above typical background soils. This is greater than 
the ARAR that has been applied at some cleanups for surface and 
subsurface soils under Superfund and State programs. As such, 
consideration of the incremental increase above background does not 
alter the overall results of this analysis. Therefore, EPA concludes 
that accumulation of CCR within the soil column can result in risks 
within the range that EPA considers or regulation.
    EPA separately considered the potential for risk to ecological 
receptors that may result from mixing of CCR with the soil based on 
comments received that a future use for these facilities could be as a 
nature preserve. EPA calculated the incremental contributions from CCR 
as described above and compared the resulting concentrations to 
available ecological benchmarks. This analysis focused on constituents 
for which ecological soil screening levels are available. This 
comparison indicates that antimony, selenium, and vanadium are most 
likely to drive risk and require further evaluation at both high-end 
and median ash concentrations. In some cases, ecological benchmarks are 
lower than typical background soil levels. However, consideration of 
the incremental increase above background does not alter overall 
results. Therefore, the potential for risk from accumulation of CCR 
within the soil column remains even if future residential land use is 
not anticipated.
vi. Final Conclusions
    Based on the analyses summarized in the current risk assessment, 
EPA concludes that there is a reasonable probability of adverse effects 
on health and the environment due to leakage from legacy CCR surface 
impoundments and CCRMU. EPA's assessment estimates that the risks that 
leakage from these units would adversely impact groundwater quality and 
pose risk to future receptors fall within the range EPA typically 
considers warrants regulation under section 4004(a) (i.e., cancer risks 
greater than 1 x 10-\5\ and non-cancer risks exceeding an HQ 
of 1). Older historical and inactive disposal units can pose risks to 
offsite receptors substantially the same as previously reported for 
currently regulated units. Smaller CCRMU fills can pose risk to onsite 
receptors and materially contribute to broader groundwater 
contamination across the facility. Depending on the location of these 
fills, they can also pose risk to offsite receptors. The risks 
identified for CCRMU fills are also believed to provide a bounding 
estimate on the risks posed by disposal units, as leakage from these 
larger units would generally be expected to result in more extensive 
releases than modeled for fills. Risks to human health from groundwater 
are anticipated to be driven by ingestion of arsenic, lithium, 
molybdenum, and/or thallium. Health effects associated with arsenic 
ingestion are an increase in the risk of cancer in the skin, liver, 
bladder, and lungs, as well as nausea, vomiting, abnormal heart rhythm, 
and damage to blood vessels. Health effects associated with ingestion 
of lithium are neurological and psychiatric effects, decreased thyroid 
function, renal effects, cardiovascular effects, skin eruptions, and 
gastrointestinal effects Health effects associated with molybdenum 
ingestion are higher levels of uric acid in the blood, gout-like 
symptoms, and anemia. Health effects associated with thallium ingestion 
are hair loss, ocular effects, and behavioral changes.
    EPA also concludes the unmonitored accumulation of CCR in surface 
and subsurface soils has the potential to result in risk to future 
human and ecological receptors in the range OLEM typically considers 
for regulation. Potential human health risks are driven by incidental 
ingestion of ash mixed with the soil and direct exposure to gamma 
radiation from radium and its associated decay chains. Health effects 
attributed to radium exposure include increased risk of several types 
of cancer, particularly lung and bone cancer. Potential ecological 
risks are driven by exposure to antimony for mammals, selenium for 
plants and mammals, and vanadium for birds from ash mixed with the 
soil. Health effects attributed to these exposures are decreased 
reproduction, growth, or survival. EPA did not seek to identify a 
comprehensive list of other contaminants that might also contribute to 
risk as part of the current assessment; however, any further risk would 
be equally addressed by controls put in place to mitigate the 
identified soil risks.

B. Legacy CCR Surface Impoundment Requirements

    The Agency is amending the CCR regulations in 40 CFR part 257, 
subpart D to require legacy CCR surface impoundments to comply with the 
same regulations that apply to inactive CCR impoundments at active 
facilities, except for the location restrictions (at Sec. Sec.  257.60-
257.64) and liner design criteria (at Sec.  257.71). EPA is also 
establishing new requirements to address issues specific to legacy CCR 
surface impoundments. Finally, EPA is establishing new compliance 
deadlines for legacy CCR surface impoundments.
1. Definition of a ``Legacy CCR Surface Impoundment''
    EPA is finalizing the proposed definition of a ``legacy CCR surface 
impoundment'' without revision. A legacy CCR surface impoundment must 
meet three criteria: (1) The unit meets the definition of a CCR surface 
impoundment; (2) The unit contains both CCR and liquids on or after 
October 19, 2015; and (3) The unit is located at an inactive electric 
utility or independent power producer. An inactive impoundment must 
meet all three criteria to be a legacy CCR surface impoundment. This 
definition is codified in Sec.  257.53.
    EPA estimates there are 194 legacy CCR surface impoundments located 
at 85 facilities that will be subject to the requirements of this final 
rule.\40\ This estimate also takes into account the information 
received in response to the Agency's lists of potential legacy CCR 
surface impoundments published in the dockets with the proposed rule 
and

[[Page 38981]]

subsequent notice of data availability. This estimate is an increase 
from the 127 legacy CCR surface impoundments located at 59 facilities 
identified in the proposed rule. 88 FR 32028.
---------------------------------------------------------------------------

    \40\ An updated list of potential legacy CCR surface 
impoundments can be found in the docket for this action. See 
document titled ``Universe of Legacy CCR Surface Impoundments. April 
2024.''
---------------------------------------------------------------------------

    The sections below briefly explain what EPA proposed, summarize the 
public comments received, and provide the Agency's responses.\41\ The 
Agency addresses several aspects of the definition in the following 
order: (1) Date for determining applicability; (2) The requirement to 
contain both CCR and liquids; and (3) The requirement to be located at 
an inactive facility.
---------------------------------------------------------------------------

    \41\ EPA's responses to public comments can be found either in 
this preamble or the Response to Comments document available in the 
docket.
---------------------------------------------------------------------------

a. Legacy CCR Surface Impoundment--Date for Determining Applicability
    EPA explained in the proposed rule that the 2015 CCR Rule exempted 
``inactive surface impoundments at an inactive facility'' and codified 
definitions of an ``inactive CCR surface impoundment'' and an ``active 
facility or active electric utility.'' The Agency further stated that 
in developing a definition of a ``legacy CCR surface impoundment'' two 
separate components need to be addressed: (1) The definition of an 
``inactive CCR surface impoundment''; and (2) The definition of an 
``inactive facility or electric utility.'' 88 FR 31989.
    At proposal, the Agency relied on the existing definitions of an 
``inactive CCR surface impoundment'' and ``active facility or active 
electric utilities or independent power producers,'' as well as the 
2018 USWAG decision to inform the options discussed. Specifically, EPA 
explained that both terms establish applicability based in part on the 
effective date of the 2015 CCR Rule--a unit is an ``inactive CCR 
surface impoundment'' if it does not receive CCR on or after October 
19, 2015, and still contains both CCR and liquids on or after October 
19, 2015, and an ``active facility or active electric utilities or 
independent power producers'' is only active if it was in operation on 
or after October 19, 2015. 40 CFR 257.53.
    The Agency proposed to define a legacy CCR surface impoundment, in 
part, as a surface impoundment that contained both CCR and liquids on 
or after October 19, 2015. EPA explained in the proposed rule, that 
using October 19, 2015 as the date to determine applicability was most 
consistent with the USWAG decision; first because legacy CCR surface 
impoundments would be regulated the same as the currently regulated 
inactive impoundments at active facilities. Second, an October 19, 2015 
applicability date would restore the status quo, as intended by court's 
decision to vacate the exemption. EPA also concluded that this was the 
most protective option. 88 FR 31990-31991. However, as an alternative, 
the Agency also solicited comment on defining a legacy impoundment as a 
unit that contains both CCR and liquids on or after the effective date 
of this final rule in 2024. 88 FR 31991-92.\42\
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    \42\ EPA also published an ANPRM on October 14, 2020 (85 FR 
65015). The Agency solicited input on a potential definition of a 
legacy CCR surface impoundment in the ANPRM and addressed comments 
to the ANPRM in the subsequent proposal. 88 FR 31989-91.
---------------------------------------------------------------------------

    Several commenters opposed the proposed applicability date of 
October 19, 2015, stating that the only legally defensible and workable 
approach is to establish an applicability date based on the effective 
date of this final rule. Some of these commenters argued that an 
applicability date of October 19, 2015, would constitute a retroactive 
rule, which they considered to be both legally impermissible and 
unreasonable. These commenters stated that establishing an 
applicability date based on the effective date of this final rule would 
honor the bedrock administrative principle that ``rules should apply 
prospectively absent express statutory grant'' consistent with Bowen v. 
Georgetown Univ. Hosp., 488 U.S. 204, 208-09 (1988).
    Other commenters stated that EPA was overreading the USWAG decision 
and inappropriately interpreting the court's decision. These commenters 
stated that the court did not specify how legacy impoundments should be 
regulated, or the appropriate applicability date and regulatory 
controls that should apply to the units but remanded those issues to 
EPA to address through rulemaking. These commenters further stated that 
the court's ruling was based on the administrative record for the 2015 
CCR Rule, which they claimed is very different than the current record 
for the facilities that would be covered by the proposal. According to 
these commenters, the court was focused only on those legacy 
impoundments for which significant risks remained, which they 
characterized as exclusively CCR surface impoundments with a hydraulic 
head. These commenters argue that, by contrast, the proposal will also 
apply to CCR surface impoundments for which EPA has failed to 
demonstrate any significant level of risk, which they characterized as 
(1) CCR impoundments that contain ``any amount of water,'' but no 
hydraulic head; and (2) CCR impoundments that are in the process of 
closing or have completed closure.
    Several commenters similarly raised concern that the proposal 
ignores that there have been numerous changes since the court issued 
its decision in 2018. For example, some commenters stated that 
facilities have proactively worked with their States to close these 
impoundments and have invested substantial resources to close these 
units in compliance with existing regulatory requirements and thus 
these units should not be considered legacy impoundments. According to 
these commenters, the final rule should take into account the 
significant closure and corrective action work that has been undertaken 
since the 2015 CCR Rule was promulgated, rather than assuming the 
landscape has not changed over subsequent years.
    In addition, a number of commenters noted that the proposed 
definition would capture numerous sites where former legacy CCR surface 
impoundments were closed by removal under then-applicable State 
regulations and where no CCR remains. These commenters raised concern 
that EPA lacks jurisdiction under RCRA to impose requirements at a site 
once all CCR has been removed. Many of these commenters further 
asserted that EPA should accept such closure as sufficient to protect 
the environment and not seek to impose an unnecessary set of 
requirements. Finally, some commenters explained that some of these 
sites have subsequently been restored and are now home to established 
natural ecosystems, and thus it would be counterproductive to require 
them to be disturbed.
    By contrast, a number of commenters asserted that the record has 
not significantly changed since the court issued its opinion. These 
commenters stated that all legacy impoundments, including those that 
have been dewatered or completed closure, pose significant risks to 
human health and the environment that warrant regulation under RCRA. 
Citing the USWAG decision and EPA's findings from the 2015 CCR Rule and 
the proposal, these commenters stated that the risks associated with 
legacy impoundments are greater than currently regulated units because 
they are more likely than regulated ponds to be unlined, more likely 
not to have been designed by a professional engineer, and more likely 
to contain a mix of ash and coal refuse, all of which increase the 
potential for groundwater contamination. The commenters further noted 
that harm from contaminant releases from legacy ponds worsens as time 
passes, citing the

[[Page 38982]]

finding in EPA's 2014 Risk Assessment that peak contaminant releases 
from CCR surface impoundments will not occur until 70 years after waste 
placement.
    These commenters also estimated that close to half a million people 
live within 1 mile of the 417 active and inactive coal-fired power 
plants in 44 States and Puerto Rico that have reported coal ash units. 
Using the Council on Environmental Quality's (CEQ) Climate and Economic 
Justice Screening Tool (CEJST), the commentor estimated that 
approximately half (213) of the facilities are located within a mile of 
a disadvantaged community, while over 70% of the facilities (297 of 
417) are located near a community that has higher-than-State average 
levels of low-income populations or populations of color. These 
commenters also estimated that many of the communities living nearby 
may experience cumulative impacts from other threats. CEJST offers data 
at the census tract-level on PM2.5 exposure, diesel 
particulate matter, traffic proximity, abandoned mine land, formerly 
used defense sites, hazardous waste site proximity, Superfund site 
proximity, underground storage tanks and releases, wastewater 
discharge, and Risk Management Plan site proximity. According to the 
commentor, using CEJST, more than half of the 417 power plants with 
historic or active ash units (214) are within one mile of a census 
tract that experiences pollution from at least two of these additional 
sources to a degree higher than that of 75% of all census tracts in the 
United States.
    The commenters also discussed several individual legacy 
impoundments with longstanding groundwater contamination, noting that 
for several plants, due to lack of Federal regulation and oversight, 
little or no action has been taken to remediate clearly documented 
contamination. Among those they highlighted were:
     At the Muskingum River Power Plant, where onsite 
groundwater has exceeded the primary EPA MCLs for barium and gross 
alpha as well as EPA secondary MCLs (SMCLs) for iron, sulfate, and 
Total Dissolved Solids. According to the commenter no remediation has 
occurred to date.
     At the retired Dynegy Vermilion Power Station in Oakwood, 
Illinois, 70-year-old unstable pits with more than 3 million tons of 
CCR are leaking CCR constituents into Illinois' only National Scenic 
River. The pits run along the river for a half-mile where kayaking and 
other recreational activities are common.
     At American Electric Power's retired Tanners Creek in 
Lawrenceburg, Indiana, leaking ash pits at the plant are contaminating 
groundwater with high levels of boron within 500 feet of public 
drinking water wells and the Ohio River.
     At Georgia Power's retired Plant Arkwright, the unlined 
abandoned ash ponds have been leaking chemicals, such as boron, at 
levels above health standards into the groundwater and nearby Ocmulgee 
River for nearly 20 years, according to a peer-reviewed study.\43\
---------------------------------------------------------------------------

    \43\ J.S. Harkness et al., Evidence for Coal Ash Ponds Leaking 
in the Southeastern United States. Environmental Science & 
Technology, 50(12): 6583-6592 (2016).
---------------------------------------------------------------------------

    According to these commenters, substantial risks to human health 
and the environment remain even where the impoundment has been 
dewatered or closed. In support of this conclusion, the commenters 
pointed to EPA's explanation in the proposal that even if impoundments 
have been at least partially dewatered or have undergone some type of 
closure, the current risks to human health and the environment can 
still be significant, due to contamination remaining at the site from 
releases that occurred while the unit was operating. Referencing data 
that legacy impoundments are, on average, 55 years old, the commenters 
also pointed to the proposal's explanation that the potential magnitude 
of releases from older units are greater than for currently regulated 
CCR units due to a number of factors, including (1) the likely absence 
of a liner in older impoundments; (2) the mixture of coal ash with coal 
refuse, which was a common disposal practice in older units; and (3) 
the older a CCR unit is, the longer it has had to leak and for 
hazardous constituents to migrate further from the unit. The commenters 
also discussed the results of a report, ``Assessment of Legacy Surface 
Impoundments'' by Gordon Johnson, M.Sc., P.Eng., which examined ten CCR 
surface impoundments at inactive facilities that were not on EPA's list 
of potential legacy ponds and do not appear to contain standing water, 
and concludes that all posed significant risks to health and the 
environment.
    As a consequence, these commenters criticized EPA's proposed 
definition of a legacy impoundment as one that contains liquid on or 
after October 19, 2015. These commenters argue that this would exclude 
surface impoundments at inactive plants that pose a reasonable 
probability of adverse effects on health and environment, whether or 
not they contain liquid.
    Several commenters also supported EPA's proposal to regulate units 
at sites that are heavily vegetated or redeveloped on the surface with 
established natural ecosystems, stating that the possibility that 
conducting a proper closure might disrupt the current land use is 
outweighed by the fact that inadequately closed units pose ongoing 
threats to health and the environment. These commenters also supported 
coverage of legacy impoundments that had completed or were undergoing 
closure pursuant to State programs, citing EPA's review of State 
programs as part of the 2015 CCR Rule, which concluded that significant 
gaps remain in many State programs, and discussing specific examples of 
problematic State permits.
    Some commenters also stated that the proposed applicability date of 
October 19, 2015, presents serious practical challenges to 
implementation because it requires facilities to look back more than 
eight years to determine the historical status of legacy impoundments. 
Commenters explained that this extended look-back period could prove to 
be an impossible task for sites where power plant operations ceased 
decades ago. Furthermore, the proposed applicability date illegally 
requires actions by facilities that are physically impossible. For 
example, operating records, construction and inspection reports, 
groundwater monitoring data, and employee testimonials may not exist 
for some facilities that ceased generating power decades ago. In 
addition, commenters pointed out that historic aerial photography will 
not inform whether liquids are present beneath the surface of the 
inactive impoundments. Finally, some commenters stated that EPA's 
proposed approach is particularly challenging to small public power 
utilities given their size, staffing levels, and record retention 
policies once a facility is closed.
    After considering the comments and all of the information in the 
record, this final rule adopts the proposed date of October 19, 2015, 
for determining applicability for legacy CCR surface impoundments. This 
applicability date is justified for two independently sufficient 
reasons. First, it most effectively targets the risks to human health 
and environment posed by legacy impoundments. Second, it is consistent 
with the USWAG decision. Accordingly, this final rule specifies that an 
inactive impoundment at an inactive facility that contained both CCR 
and liquids on or after October 19, 2015, is a legacy CCR surface 
impoundment subject to the requirements of this final rule. The

[[Page 38983]]

definition of a legacy CCR surface impoundment is codified in Sec.  
257.53.
    This option best addresses the risks legacy impoundments pose to 
human health and the environment. EPA's record for this rule, which 
includes the 2015 rulemaking record, supplemented by new information, 
establishes that that the environmental risks posed by legacy 
impoundments are greater than or similar to those posed by operating 
impoundments. EPA acknowledges that it is not bound by the 2015 
rulemaking record that the court reviewed in USWAG--and, as just 
stated, in fact has supplemented that record with new information for 
this rulemaking. EPA further acknowledges that since the 2015 CCR Rule 
and the USWAG decision some units have closed or have begun to close in 
accordance with State permits, or on their own initiative in response 
to the D.C. Circuit's ruling. But EPA disagrees that the record shows 
that the risks to human health and the environment posed by the legacy 
impoundments regulated under this final rule are significantly or 
meaningfully lower than the risks the court found to be unacceptable in 
USWAG. In fact, as described in III.A.4 of this preamble, the record 
instead demonstrates that the totality of the risks is potentially 
greater than EPA estimated in 2014.
    A subset of legacy impoundments is identical to those described in 
USWAG; the impoundments are structurally unstable and pose significant 
risk of contaminating groundwater because they are unlined, with a 
hydraulic head promotes the continual leaching of contaminants from the 
CCR and drives the resulting leachate into underlying soils and 
potentially into the underlying aquifer. No commenter disagreed that 
these legacy impoundments warrant regulation under part 257.
    Another subset, on which many of the commenters largely focused, 
have been fully or partially dewatered, or have completed some form of 
closure. In response to the proposal, EPA received information that 
since October 19, 2015, 22 surface impoundments at inactive facilities 
have closed by removal or are in the process of closing by removal, and 
10 surface impoundments have closed with waste in place, either with 
oversight from a State agency or on their own initiative in response to 
the USWAG decision. These commenters claimed that, as a consequence of 
dewatering their units, the units no longer pose any appreciable risk.
    EPA agrees that once the water in the impoundment has been reduced 
the likelihood of structural failure will also have been reduced; and 
if the liquid and or CCR have been entirely removed there will be no 
appreciable risk of structural failure. But these units nevertheless 
continue to present significant risk to human health and the 
environment as a consequence of existing--and in some cases, 
continuing--groundwater contamination. This contamination can exist 
even where CCR has been entirely removed from the disposal unit. First, 
in many cases facilities have only removed some of the free liquids in 
the impoundment; that is, have only partially dewatered. As described 
in Unit III.B.2.g of this preamble, many commenters claimed that under 
the existing closure regulations they are only required to eliminate 
free liquids to the extent necessary to support heavy machinery or 
other construction activities (i.e., to the extent necessary to support 
the cover system), rather than to eliminate free liquids without 
qualification, as the regulation requires. Such units present 
essentially the same environmental and human health risks the USWAG 
court was concerned with. Second, to the extent a unit intersects with 
groundwater, free liquids will remain (because the groundwater is 
continually saturating the CCR), and the unit will continue to present 
significant risks, because the same conditions that promote the rapid 
leaching of contaminants in operating units are present, and will 
persist indefinitely. Finally, at many of these sites the existing 
contamination resulting from when the unlined impoundment was operating 
has not been addressed. Each of these are discussed further below.
    Contrary to the commenters' claims, the partial dewatering they 
describe does not, as they claim, ``eliminate'' either the hydraulic 
head from a unit or the risk of groundwater contamination. Until the 
water (liquid) is fully removed, gravity will continue to exert 
downward pressure on the water in the saturated waste until it reaches 
equilibrium with the water table. Thus, although reducing the water in 
the unit also reduces hydraulic head, hydraulic head will be present as 
long as water remains in the unit.
    Hydraulic head represents the energy to move a liquid. Liquid flows 
from locations of higher hydraulic head to locations of lower hydraulic 
head. A simple illustration of hydraulic head is the water percolating 
through (i.e., exerting downward pressure on) coffee grounds into the 
cup below. As the water moves through the solids, particles of the 
solids combine with the water (create leachate) and drain downward. 
Even after the water is no longer visible above or among the coffee 
grounds, liquids continue to drain into the cup below.
    In a diked impoundment located above the water table, after the 
removal of free standing (or ``ponded'') water, the CCR in the unit 
would still remain saturated with liquids (i.e., the free liquid \44\ 
and/or porewater). Once the CCR material is saturated, some liquids may 
remain bound within the CCR due to retention forces. However, the 
remaining (free) liquids will drain in response to gravity and 
hydraulic head. Because the saturated waste is at a higher elevation 
than the normal water table, the free liquids within the saturated 
waste would continue to drain toward the normal water table (``exert 
downward pressure'') even if the unit no longer contained ponded water 
on top of the CCR. Until the water is eliminated from the CCR, gravity 
will continue to exert downward pressure on the water in the saturated 
waste, but at some point, gravity will be insufficient to overcome the 
retention forces in the CCR. Until that point, free liquids will 
continue to drain until they reach the water table. Continued contact 
with free liquids causes the metals and other constituents to leach out 
of the CCR, and the downward pressure of the hydraulic head drives the 
resulting leachate toward the bottom and sides of the unit. In an 
unlined unit, which the overwhelming majority of legacy impoundments 
are likely to be, any remaining free liquids saturating the CCR in the 
impoundment will eventually leak out of the unit into the surrounding 
soil and/or into the aquifer, along with any CCR constituents that have 
leached from the waste in the interim. As mentioned previously, it is 
important to note that after this draining occurs, some liquids will 
remain bound within the pore spaces of the CCR material and will not 
readily drain under ambient temperature and pressure. Consequently, 
these residual liquids are not free liquids. Because any remaining 
residual liquids (e.g., bound porewater or potential leachate) will not 
continue to drain from the unit absent other forces, further releases 
of these residual liquids are not likely.
---------------------------------------------------------------------------

    \44\ Free liquids are any liquids that readily separate from the 
solid portion of a waste at ambient temperature and pressure. Sec.  
257.53. In the example described above, free liquids are the liquids 
that drain from the coffee into the cup below.
---------------------------------------------------------------------------

    By contrast, when some portion of the unit has been constructed in 
or below the water table, even if the hydraulic head is reduced by the 
removal of free-standing or ponded water, hydraulic head remains 
present as long as groundwater flows through the unit

[[Page 38984]]

from higher groundwater elevations to lower groundwater elevations. And 
even where the CCR above the water table in such a unit has been 
partially or fully dewatered, the ``conditions that promote rapid 
leaching of contaminants'' still remain as a consequence of the 
continued saturation of CCR in the unit from groundwater infiltrating 
the unit.
    As EPA explained in Unit III.A.2 of this preamble, a CCR landfill 
saturated with water during operation, either continuously or 
intermittently, would behave more like an operating CCR surface 
impoundment even though such a unit would not have the level of 
hydraulic head from ponded water present in an operating impoundment. 
The same is true of a dewatered legacy impoundment constructed in or 
below the water table. See also 88 FR 32011. The hydraulic head from 
the ponded water in an operating impoundment unit allows for continual 
leaching of contaminants from CCR and drives the resulting leachate 
into the underlying soils and potentially into the underlying aquifer. 
However, where any part of the unit is actually constructed below the 
water table, the conditions caused by the continuous saturation of the 
CCR by the groundwater flowing in and out of the unit allow the 
contaminants to continuously leach directly into the nearby ground and 
surface waters even without any downward pressure from hydraulic head 
pushing leachate out of the unit. Id.
    The record shows that significant numbers of the currently 
regulated CCR surface impoundments were constructed such that the base 
of the unit intersects with groundwater,\45\ and that many inactive, or 
even ``closed,'' impoundments continue to impound water below the water 
table (i.e., contain liquids).
---------------------------------------------------------------------------

    \45\ EPA's review of the location restrictions demonstrations 
posted on facilities' CCR websites found that approximately 31% of 
operating impoundments have waste below the water table. There is no 
reason to believe that this percentage is not also representative of 
legacy impoundments.
---------------------------------------------------------------------------

    In any event, even if an impoundment has been completely dewatered, 
the current absence of impounded water does not remediate the releases 
that occurred during operation of the unit. In general, legacy 
impoundments are likely to have been present for longer than the 
currently operating units: For example, one commenter presented 
information to demonstrate that legacy impoundments are, on average, 55 
years old; by comparison, EPA estimated in 2015 that most currently 
operating surface impoundments were between 20 and 40 years old. See 80 
FR 21327. This is significant in two regards: (1) The older the 
impoundment the greater the likelihood it is unlined; and (2) The more 
time the unlined unit would have to leak and for hazardous constituents 
to migrate further from the unit. Consequently, previous and ongoing 
releases could potentially be greater and have migrated further from 
the unit than releases from the universe of currently regulated units. 
In this regard, it is notable that EPA estimated in its 2014 Risk 
Assessment that peak contaminant releases from CCR surface impoundments 
will not occur until 70 years after waste placement. This is further 
confirmed by the modeling originally conducted in 2014 for legacy 
impoundments.
    Furthermore, as described in Unit III.A there are a number of 
additional reasons to believe that the potential magnitude of releases 
is even greater than EPA originally estimated in 2014. These include: 
(1) The likely absence of a liner at older impoundments; and (2) The 
greater likelihood that coal ash was managed with coal refuse, which 
was a common disposal practice in older units.
    Finally, defining a legacy impoundment as one that contains both 
CCR and liquid on or after October 19, 2015, retains oversight of units 
that may have been dewatered but have not yet completed closure. In any 
unit without an effective cover system, precipitation can continue to 
freely migrate into the unit, and any leachate generated as a result 
would be a potential ongoing source of contamination, particularly 
where the unit is already leaking or in contact with groundwater. 
Further, significant risks can remain if a unit is not closed properly; 
for example, a closure that leaves that millions of tons of CCR 
saturated with groundwater and only a cover system to control downward 
infiltration of precipitation will not protect human health and the 
environment. And, as discussed in further detail in the next section, 
even at sites where the CCR has been completely removed from the 
impoundment it is possible that, in addition to the likely significant 
groundwater contamination present at the site, contaminated soil 
remains, which can serve as a source of further contamination. See, 
Unit III.B.1.b.ii.(a).
    EPA acknowledges that some of these units may be closing pursuant 
to State laws that provide for a significant degree of State 
involvement and oversight, but that is not universally the case. As EPA 
concluded in 2015, there is a wide range of protectiveness in State 
programs. Clear deficiencies were present in some State regulatory 
programs, and questions remained with respect to others. See, 80 FR 
21326-21327, 21456 and Unit III.B.g.iii. EPA is aware that some State 
programs have been substantially revised since 2015, and some 
individual States provided additional information regarding their 
programs in their comments, but again this is not universal. For 
example, some commenters documented recent State approved closures that 
were deemed complete despite the absence of any groundwater monitoring 
to determine whether groundwater contamination remained at the site. 
The absence of a consistent, sufficiently protective approach among all 
State programs reinforces the need for a single, protective Federal 
standard.
    EPA also continues to believe that an applicability date of October 
19, 2015, is the most consistent with the USWAG decision. See, 88 FR 
31991. The Court expressly found that EPA's record for the 2015 CCR 
Rule demonstrated that legacy ponds ``pose the same substantial threats 
to human health and the environment as the riskiest Coal Residuals 
disposal methods, compounded by diminished preventative and remediation 
oversight due to the absence of an on-site owner and daily 
monitoring.'' 901 F.3d at 432. EPA agrees with this conclusion that 
legacy ponds ``pose substantial risk to human health and the 
environment.'' Id. Consistent with that determination, the final rule 
imposes essentially the same requirements on legacy CCR surface 
impoundments that currently apply to inactive impoundments at active 
facilities. In addition, as EPA explained in the proposed rule, D.C. 
Circuit's decision setting aside the exemption for inactive 
impoundments meant that these impoundments were similarly situated to 
the impoundments regulated by the 2015 CCR Rule. EPA thus had an 
obligation to address the substantial environmental risks from those 
impoundments through regulation. By setting aside, rather than simply 
remanding the exemption back to the Agency for further explanation, the 
Court made clear that the existing record was sufficient for these 
units to be regulated.
    Nor is EPA persuaded by the commenters' remaining objections to the 
applicability date of October 19, 2015. EPA disagrees that reliance on 
the effective date of the 2015 CCR Rule would constitute a retroactive 
application of law. A regulation is impermissibly retroactive where, 
absent clear Congressional intent, the rule changes the past legal 
consequences of past conduct. See Bowen v. Georgetown Univ. Hosp., 488 
U.S. 204, 208 (1988). This is generally referred to as primary

[[Page 38985]]

retroactivity. See Bergerco Canada, a Div. of Conagra, Ltd. v. U.S. 
Treasury Dep't, Off. of Foreign Assets Control, 129 F.3d 189, 192 (D.C. 
Cir. 1997). Rules can also affect the legal rights flowing from past 
acts. See Bergerco, 129 F.3d at 192. This is referred to a secondary 
retroactivity. Id. Such effects are common, and permissible so long as 
they are not arbitrary or capricious. The D.C. Circuit in Bergerco 
noted that a rule may be arbitrary or capricious if it ``makes 
worthless substantial past investment incurred in reliance upon the 
prior rule.'' Id.
    Here EPA is merely relying on a past fact to support the future 
application of regulations. And because EPA has established future 
compliance dates, no facility would be subject to penalties solely 
because one of its legacy CCR surface impoundments was out of 
compliance with the regulatory requirements prior to the effective date 
of this final rule. Thus, the rule is not primarily retroactive.
    To the extent the rule has secondary retroactive effects in 
upsetting parties' expectations of regulation of legacy CCR surface 
impoundments and CCMRU, such effects are permissible. First, the D.C. 
Circuit considered and rejected this same argument in Util. Solid Waste 
Activities Grp. v. Env't Prot. Agency, 901 F.3d 414 (D.C. Cir. 2018). 
There, industry petitioners argued that EPA lacked statutory authority 
to regulated legacy CCR surface impoundments because such regulation 
would be retroactive. The D.C. Circuit held that ``straightforward 
reading of the statute's language allows for the regulation of inactive 
sites.'' Id. at 439. In short, as facilities ``where solid waste is 
disposed of,'' 42 U.S.C. 6903(14), inactive impoundments are ``open 
dumps,'' And no one denies that the EPA has authority to regulate (and 
to prohibit) ``open dumps.'' Id. at 441.
    Moreover, as explained in detail below, EPA rationally explained 
why regulation was necessary and appropriate here notwithstanding 
facilities' reliance interests. EPA understands that facilities may 
have closed legacy impoundments and treated CCMRU in compliance with 
State law requirements, or otherwise made business decisions premised 
on the absence of Federal regulation. EPA has taken these reliance 
interests into account in developing the regulations here. As explained 
below, EPA surveyed State regulation of legacy impoundments and CCMRU 
and concluded that, on the whole, such regulations were not 
sufficiently protective, and did not meet RCRA's standard. Uniform, 
national regulation was therefore necessary to ensure adequate 
protection of human health and the environment. To be sure, EPA 
recognizes that it is possible that some legacy impoundments, for 
example, may have been closed in a manner that is protective. But, due 
to the absence of adequate groundwater monitoring and other data, the 
adequacy of such closures cannot be verified. EPA has also accounted 
for other reliance interests, including renewable facilities' use of 
land containing CCRMU, in establishing compliance deadlines, and 
allowing for deferrals of additional closure measure where appropriate. 
EPA also notes that regulated entities have been on notice since the 
D.C. Circuit's 2018 decision in USWAG that Federal regulation of legacy 
CCR surface impoundments was forthcoming, 901 F.3d at 414.
    A number of commenters also claimed that their units are heavily 
vegetated or developed and that reopening or other removal/remediation 
activities may disrupt the current use of the site. EPA acknowledges 
some old units may be heavily vegetated. However, no commenter 
submitted any data or analysis to demonstrate that, over the short or 
long term, removal or remediation activities would be more detrimental 
to health and the environment than either cleaning up the contaminated 
groundwater or taking measures to prevent the legacy CCR surface 
impoundment from contaminating groundwater.
    Moreover, the fact that some impoundments have become heavily 
vegetated or redeveloped does not resolve the risks these unlined 
legacy CCR surface impoundments continue to pose. As discussed above, 
the risks associated with such units can be substantial. See Unit III.A 
of this preamble for more information. Consequently, the current record 
does not support an exemption for units that still contain both liquid 
and CCR even if the closure or remediation may disrupt the current use 
of the land.
    As discussed in more detail in the subsequent section, EPA also 
disagrees that the removal of CCR from a disposal unit necessarily 
demonstrates that EPA lacks jurisdiction over the site. EPA's 
jurisdiction rests on the presence of solid waste that ``is disposed 
of'' at the site, not solely the presence of CCR. To the extent any CCR 
leachate or CCR constituents remain in the soil or in the aquifer at 
the site, solid waste remains at the site and EPA retains jurisdiction. 
However, as EPA stated in the proposal, the Agency agrees that it lacks 
jurisdiction over a site where the owner or operator can document that 
it meets the standard for closure by removal in Sec.  257.102(c). 
Accordingly, the final rule retains the provision specifying that any 
facility that documents that this standard has been met will not be 
subject to any further requirements. See Units III.B.2.b.iii and 
III.B.2.g of this preamble for further discussion.
    The Agency disagrees that adopting an applicability date of October 
19, 2015, requires actions that are physically impossible or that the 
implementation challenges cannot be addressed. The final rule does not 
require owners and operators to acquire historical operating records, 
construction and inspection reports, groundwater monitoring data, and 
employee testimonials where they no longer exist, or where they have 
never existed. EPA acknowledges that such information will not be 
available in some situations. Rather, EPA expects owners and operators 
of inactive impoundments at inactive facilities to develop a strategy 
to gather readily available and reliable information to determine 
whether the unit meets the definition of a legacy CCR surface 
impoundment. If, after making a good faith effort a facility is 
genuinely unable to obtain information to document that the impoundment 
contained both CCR and liquids on October 19, 2015, the unit would not 
be regulated as a legacy impoundment. See Unit III.B.2.b.i of the 
preamble for an explanation of the actions the Agency expects owners 
and operators to take to determine whether the inactive impoundment 
meets the definition of a legacy CCR surface impoundment.
    Nevertheless, EPA agrees that the final rule should account for the 
significant closure work that has taken place at some legacy CCR 
surface impoundments between October 19, 2015, and the effective date 
of this final rule. For example, as noted, commenters provided several 
examples of closures that were completed prior to the effective date of 
this final rule. The final rule accounts for this not by exempting 
these units but by modifying the applicable requirements. A facility 
that can document that it has met the criteria in Sec.  257.102(c) 
would be subject only to the requirement to document that they had met 
those standards. Similarly, a facility that completed closure with 
waste in place before the effective date of this final rule would only 
be subject to the closure performance standards in Sec.  257.102(d), 
and the post-closure care requirements (i.e., groundwater monitoring 
and corrective action, if necessary). In addition, a facility that 
completed closure under a regulatory authority's oversight and 
approval, such

[[Page 38986]]

as pursuant to a Federal or State cleanup order could be subject to 
even fewer requirements. Provided certain conditions have been met EPA 
is deferring a decision on the adequacy of such closures to a 
subsequent permitting authority to determine on an individual site-
specific basis, whether the completed closure meets the Federal 
performance standards in Sec.  257.102 or is equivalent to (i.e., is as 
protective as) such a closure. In the interim, these units would be 
subject only to the requirements of a post closure care permit (i.e., 
groundwater monitoring and corrective action, if necessary). See Unit 
III.B.2 of the preamble for further explanations of these provisions. 
As EPA stated in the proposal, units that contain liquid present 
different risks than those that do not, and the applicable requirements 
should differentiate among them accordingly on that basis. See 88 FR 
31993.Consistent with that logic, while EPA agrees that legacy 
impoundments that were dewatered or closed prior to October 19, 2015 
can still pose significant risks to human health and the environment, 
as discussed in the next section, the final rule retains the approach 
described in the proposal, and requires that an impoundment contain 
both liquid and CCR on or after October 19, 2015 to be regulated as a 
legacy impoundment.
b. Legacy CCR Surface Impoundment--Definition of an Inactive 
Impoundment--Contains Both Liquid and CCR
    The final rule requires that to be considered a ``legacy CCR 
surface impoundment'' a CCR surface impoundment must have contained 
both CCR and liquids on or after October 19, 2015. In addition, the 
final rule further defines what it means to contain both CCR and liquid 
by reference to Sec.  257.102(d)(2)(i). In this Unit of the preamble, 
the Agency briefly explains what was proposed, summarizes the public 
comments received, and provides EPA's responses. EPA first discusses 
what it means for an impoundment to ``contain liquids'' followed by 
what it means to ``contain CCR.''
i. What does it mean to contain liquid?
    Consistent with the definition of an inactive CCR surface 
impoundment at active facilities under the existing regulations, EPA 
proposed in the May 2023 proposed rule that a legacy impoundment would 
be required to have contained liquids on or after October 19, 2015, in 
order to be subject to the requirements of this rule. In the proposed 
rule, EPA also responded to comments previously raised in response to 
the ANPRM, alleging that the phrase ``contains both CCR and liquids'' 
was impermissibly vague. These commenters were concerned that the 
definition might not include those units whose bases are in contact 
with groundwater or that no longer have visible, standing water at the 
surface. EPA further responded to questions whether, based on the 
existing definition of an inactive CCR surface impoundment, the 
following would be considered a legacy CCR surface impoundment: (1) 
Where, prior to October 19, 2015, the facility has decanted the surface 
water, but, because the base of the impoundment intersects with the 
groundwater, water continues to flow through the impoundment and 
permeate the waste in the base of the unit; (2) Impoundments that 
contained both CCR and liquids in the past but are now closed; (3) 
Impoundments that contained CCR and liquids in the past but are in the 
process of closing on the effective date of the legacy rulemaking; and 
(4) Impoundments that once contained CCR and liquids but have been 
fully dewatered and are now maintained so as to not contain liquid.
    EPA explained that the answers to these questions turn on the 
meaning of the terms ``contain'' and ``liquids'' in the definition of 
an inactive impoundment in Sec.  257.53. Relying on dictionary 
definitions, EPA explained that the term ``liquids'' includes the free 
water, porewater, standing water, and groundwater in the unit, because 
once any are present in the unit, they have the same potential to 
create leachate, as well as to contribute to hydraulic head and drive 
flows propelled by hydraulic gradients. 88 FR 31992. EPA also explained 
that based on dictionary definitions an impoundment ``contains'' liquid 
if there is liquid in the impoundment, that is, it has water within it, 
even if water continues to leak from the unit. EPA also stated that as 
a factual matter, a surface impoundment that has only decanted the 
surface water would normally still contain liquid if the CCR was still 
saturated with water.
    Accordingly, EPA explained that to the extent the unit still 
contains liquids on or after October 19, 2015, it is considered an 
inactive impoundment under the existing definition in Sec.  257.53. EPA 
proposed that such units would also be considered legacy CCR surface 
impoundments, when located at inactive facilities. EPA also explained 
that under the proposal, such an impoundment would be considered a 
legacy CCR surface impoundment: (1) Even if it is considered ``closed'' 
under State law; (2) It is in the process of closing on the effective 
date of this rule; or (3) The unit is only fully dewatered and can no 
longer impound liquid after October 19, 2015.
    EPA further explained that to determine whether an impoundment has 
been dewatered, EPA relies on the existing requirements in Sec.  
257.102(d)(2)(i) (``Free liquids must be eliminated by removing liquid 
wastes or solidifying the remaining wastes and waste residues''). EPA 
explained that this provision requires a facility to eliminate both the 
standing liquid in the surface of the impoundment and the separable 
porewater in any sediment located in the base of the impoundment, 
regardless of the source of the standing water or porewater (i.e., 
whether it was present in the impoundment due to surface water 
infiltration, intentionally added sluice water, or groundwater 
intrusion).
    EPA also solicited comment on whether to adopt a regulatory 
definition of the term ``liquids'' to clarify that the term includes 
free water, porewater, standing water, and groundwater.
    Finally, the Agency explained that under the existing regulations, 
an impoundment that did not contain liquids prior to October 19, 2015, 
whether because it was closed in accordance with existing State 
requirements or for other reasons, is not an inactive impoundment. 
Similarly, a unit that still contains both CCR and liquid after that 
date would still be considered an inactive unit even if it was closed 
in accordance with the requirements in effect at the time (e.g., has a 
cover). Consistent with this definition, EPA proposed not to expand the 
definition of a legacy CCR surface impoundment to include units that no 
longer contained any liquid on October 19, 2015. 88 FR 31993.
(a) Pending Litigation Over EPA's Regulatory Interpretations
    A number of commenters claimed that the interpretation of 
``liquids'' presented in the preamble was first announced in connection 
with proposed Part A determinations in January 2022, and is currently 
being litigated in the D.C. Circuit Court of Appeals in multiple cases 
combined under the name, Electric Energy, Inc., et al. v. EPA, Case 
Nos. 22-1056 and 23-1035.\46\ These

[[Page 38987]]

commenters complained that EPA makes no mention of this litigation in 
the proposed rule, even as it claims that its interpretation is 
``sufficiently clear that a definition is not necessary.'' According to 
these commenters, EPA must acknowledge (and make a good faith attempt 
to reconcile) the competing interpretations of key terms of art in the 
2015 CCR Rule before extending them into this final rule. One commenter 
further stated that if EPA ultimately elects to adopt regulatory 
definitions of those terms, it should wait until the court rules so 
that the definitions are informed by and consistent with any such 
ruling.
---------------------------------------------------------------------------

    \46\ On January 11, 2022, EPA issued determinations on 
demonstrations submitted by facilities for extensions to the cease 
receipt of waste deadline per 40 CFR 257.103(f)(1) and 
257.103(f)(2), which the Agency refers to as ``Part A 
determinations'' or ``Part A''. The CCR Part A Final Rule (85 FR 
53516, August 28, 2020), grants facilities the option to submit a 
demonstration to EPA for an extension to the deadline for unlined 
CCR surface impoundments to stop receiving waste. Facilities had 
until November 30, 2020 to submit demonstration to EPA for approval.
---------------------------------------------------------------------------

    EPA disagrees that it is necessary to wait until the court issues 
its decision in the pending litigation (Electric Energy, Inc., et al. 
v. EPA, Case Nos. 22-1056 and 23-1035). The central issue Petitioners 
raised in that case was exclusively procedural--whether EPA effectively 
amended the 2015 CCR Rule without going through notice and comment. 
Even if the D.C. Circuit addresses this procedural question, it would 
not resolve the substantive question EPA posed in the proposal, of 
whether the inclusion of a definition for the term ``liquids'' would 
provide further clarity.
    Finally, EPA considers that it has more than met any obligation to 
``acknowledge (and make a good faith attempt to reconcile) the 
competing interpretations of key terms of art in the 2015 regulation,'' 
in the proposal and again in this final rule. EPA has repeatedly 
explained its construction of the regulations in documents held out for 
public comment, including in the May 2023 proposal, and most recently, 
in the proposal to deny Alabama's application for approval of its CCR 
permit program. See, e.g., 88 FR 31992-31993, 32025-32026, 55236-55238. 
EPA has also repeatedly responded to public comments, addressing each 
of the commenters' alternative interpretations, and explaining in 
detail the reasons for the Agency's disagreement. See, e.g., 88 FR 
55237; U.S. EPA. Denial of Alternative Closure Deadline for General 
James M. Gavin Plant, Cheshire, Ohio. November 18, 2022. pp 14-42, 
Response to Comments on Proposed Denial (Docket ID No. EPA-HQ-OLEM-
2021-0590). November 2022. EPA has again responded to the commenters' 
alternative interpretations throughout this preamble and in the 
Response to Comments document in the docket. And even though EPA 
remains entirely unconvinced by the commenters' alternative 
interpretations, and without exception, considers that they are 
inconsistent with the plain language of the provisions at issue, EPA 
has responded to them by incorporating definitions of ``liquids'' and 
``infiltration'' that reflect EPA's existing construction of the 
regulations. Neither RCRA nor the APA requires anything further.
(b) Comments on the Definition of an ``Inactive CCR Surface 
Impoundment'' and the Meaning of ``Contains Liquids''
    All commenters agreed that, consistent with the existing definition 
of an inactive surface impoundment, any impoundment that ``contains 
both liquids and CCR'' at an inactive facility should be classified as 
a legacy CCR Surface impoundment. However, commenters disagreed on the 
correct interpretation of the phrase ``contains. . .liquids.'' Several 
commenters agreed with EPA's explanation in the proposal that to the 
extent an impoundment still contains liquids on or after October 19, 
2015, it is properly considered an inactive impoundment under the 
existing definition in Sec.  257.53, even if (1) The unit had 
``closed'' under State law; (2) The unit is in the process of closing 
on the effective date of this rule; or (3) After October 19, 2015 the 
unit is fully dewatered and can no longer impound liquid. These 
commenters also agreed that such units should also be considered legacy 
CCR surface impoundments when located at inactive facilities.
    But other commenters objected to proposal's construction of the 
regulation. These objections fell generally into two categories. First, 
a number of commenters argued that the discussion in the proposed rule 
reflected a ``new'' interpretation that expanded the meaning of the 
terms ``CCR surface impoundment'' and ``inactive surface impoundment'' 
by interpreting the phrase ``contains liquids'' to reach units that the 
commenters believe EPA never intended to cover in 2015. In support of 
this argument, these commenters objected to the statement in the 
proposal that free water, porewater, standing water, and groundwater 
are liquids under the existing regulation defining inactive CCR surface 
impoundments, arguing that this expands the existing definition of 
liquids to sources of water that the commenters assert ``are not 
demonstrated to be contributing to hydraulic head creating the 
potential for impoundment failure and spread of contaminated water.'' 
These commenters further claimed that the existing definition of an 
``inactive impoundment'' does not include: (1) Units ``with any amount 
of water;'' (2) Impoundments that closed prior to the effective date of 
the 2015 CCR Rule; and (3) ``Dewatered'' impoundments. These commenters 
contend therefore, that none of these units should be considered legacy 
CCR surface impoundments either. Second, a number of commenters raised 
concerns about the merits or wisdom of the approach. Many of these 
commenters also offered alternative definitions.
    In addition, as discussed in the preceding section, a number of 
commenters objected to EPA's proposal not to expand the definition of a 
legacy CCR surface impoundment to include units that no longer 
contained any liquid on October 19, 2015. These commenters argued that 
the proposed definition failed to address the full universe of surface 
impoundments at inactive plants that pose a reasonable probability of 
adverse effects on health and environment. In support of their 
contention, these commenters referenced EPA damage cases documenting 
harm to groundwater and/or surface water from impoundments that may not 
have contained liquid on or after 2015. The commenters also referenced 
a report, ``Assessment of Legacy Surface Impoundments'' by Gordon 
Johnson, M.Sc., P.Eng., that examines ten CCR surface impoundments at 
inactive facilities that were not on EPA's list of potential legacy 
impoundments and do not appear to contain standing water. According to 
the commenter, the report shows that unacceptable levels of risk may 
still be present for historical impoundments that have been dewatered 
and/or capped.
(1) What is a ``liquid''?
    The May 2023 proposed rule explained that free water, porewater, 
standing water, and groundwater are liquids under the existing 
regulation. The source of the liquid does not impact its basic and 
fundamental designation as a liquid and its contribution to the risk 
posed by an impoundment. It therefore does not matter whether the 
liquid in the surface impoundment comes from the rain, waters the 
facility deliberately places in the unit, floodwaters from an adjacent 
river, or from groundwater--all are liquids, and once present in the 
unit, they have the same potential to create leachate (another type of 
liquid), and to contribute to hydraulic head and drive flows driven by 
hydraulic gradients. 88 FR 31992.

[[Page 38988]]

    Several commenters agreed that the final rule should reflect EPA's 
existing interpretation that an impoundment containing any of the 
following types of liquid would be considered to contain liquid: free 
water, porewater, standing water, and groundwater without regard to 
their source.
    However other commenters disagreed that under the existing 
regulations the term ``liquids'' includes free water, porewater, 
standing water, and groundwater in CCR units, and disagreed that EPA 
should adopt such a definition. Many of these commenters argued that 
EPA should not focus on ``liquids'' but on ``free liquids,'' which they 
interpret to exclude groundwater. For example, one commenter asserted 
that ``the term liquids, which is used in the definition of ``free 
liquids,'' is not defined in the CCR Rule, and that the term ``free 
liquids'' was never used in relation to groundwater.'' Another 
commenter objected that the existing regulations establish two separate 
definitions of free liquids and groundwater, which they claim do not 
reference each other or refer to overlapping concepts. The commenter 
further argued that free liquids are ``liquids that readily separate 
from the solid portion of a waste under ambient temperature and 
pressure,'' but ``groundwater'' is ``water below the land surface in a 
zone of saturation,'' and that these are different things from a 
technical perspective.
    These commenters urged that regulating based on the presence of 
free liquids would be consistent with EPA's philosophy for regulating 
CCR surface impoundments because free liquids contribute to hydraulic 
head and hydraulic gradients regardless of their origin and impounded 
water must be removed from the impoundment to create a stable subgrade 
for the final cover system. Another commenter stated that this would be 
consistent with the 2015 CCR Rule, because even a unit closed under the 
existing regulatory criteria may contain some liquids after closure, so 
long as they are not free liquids.
    The final rule continues to define ``liquids'' in accordance with 
its plain language meaning, consistent with the ordinary dictionary 
definition. Reliance on the ordinary meaning here is the default, as 
neither RCRA nor the existing part 257 regulations include a definition 
of the term ``liquids.'' FTC v. Tarriff, 584 F.3d 1088, 1090 (D.C. Cir. 
2009) (quoting Williams v. Taylor, 529 U.S. 420, 431 (2000)) (``It is 
fixed law that words of statutes or regulations must be given their 
`ordinary, contemporary, common meaning.' ''). This reflects EPA's 
existing construction of the current regulations. As discussed in 
greater detail in Unit III.B.1.b.i.(b)(4), the final rule incorporates 
this definition into Sec.  257.53.
    The dictionary definition encompasses all of the various types of 
liquid that may be present in a CCR unit, including water that was 
sluiced into the impoundment along with the CCR, precipitation, surface 
water, and groundwater that has migrated into the impoundment, which 
may be found as free liquids, free water or standing water ponded above 
the CCR or porewater intermingled with the CCR. These definitions are 
consistent with the surrounding regulatory text and structure of the 
regulation as a whole, as well as the wider context in which the terms 
are employed. As a consequence, the term functions effectively in all 
of the various contexts in which it is used in part 257. This is 
particularly true of the term ``liquids,'' which plays a critical role 
in determining both whether a unit is subject to the regulations and in 
the performance standards that apply to impoundments closing with waste 
remaining on-site at Sec.  257.102(d).
    Further, reliance on this definition best achieves the statutory 
purpose of protecting human health and the environment. By accounting 
for all liquids, regardless of the source, the regulation ensures that 
the risks that legacy CCR surface impoundments pose will be addressed--
both by focusing on the impoundments that pose the greatest risks and 
by ensuring that all sources of risk are addressed in closing an 
impoundment. As explained in the proposal, the source of the liquid 
does not determine its basic and fundamental properties. It therefore 
does not matter whether the liquid in the surface impoundment comes 
from the rain, waters the facility deliberately places in the unit, 
floodwaters from an adjacent river, or from groundwater. All liquids, 
once present in the impoundment have the same potential to become free 
liquids and promote contaminant leaching and contribute to structural 
instability or failure, by contributing to the creation of leachate 
(another type of liquid), and hydraulic head.
    Contrary to the commenters' contentions there is no inconsistency 
between the regulatory definitions of groundwater and free liquids. By 
their terms the definitions of free liquids and groundwater are not 
mutually exclusive; rather, the term ``free liquids'' encompasses the 
term ``groundwater.'' Nor is there any inconsistency in applying both 
of these terms in this context. First, the word ``liquid,'' which 
appears both in the existing definitions of an inactive CCR surface 
impoundment and free liquids, is broad enough that it can encompass 
groundwater, which has been defined in Sec.  257.53 since 2015. Not all 
liquids are groundwaters, but all groundwater (water) is a liquid. And, 
where the water in the surface impoundment sits ``below the land 
surface in a zone of saturation,'' the water in the unit meets the 
regulatory definition of groundwater. 40 CFR 257.53. Moreover, nothing 
in the definition of free liquids restricts the source of the liquid. 
It therefore does not matter whether the liquid in the surface 
impoundment comes from rain, waters that the facility deliberately 
places in the unit, floodwaters from an adjacent river, or from 
groundwater--all are liquids. The only test the regulation establishes 
for free liquids is whether the liquid readily separates from the solid 
portion of the wastes under ambient temperature and pressure. Id.
    However, EPA generally agrees that regulating based on the presence 
of free liquids, albeit not based on the commenters' misinterpretation 
of the term, would be consistent with the existing regulations and the 
risks associated with CCR surface impoundments. As described in Unit 
III.A above, the risks are largely driven by the presence of free 
liquids in the unit, as these are the liquids that causes the metals 
and other constituents to leach out of the CCR, and that will 
eventually leak out of the unit into the surrounding soil and/or into 
the aquifer, along with any CCR constituents that have leached from the 
waste in the interim. Although some liquids will remain bound within 
the pore spaces of the CCR material and will not readily drain under 
ambient temperature and pressure, these residual liquids (e.g., bound 
porewater or potential leachate) will not continue to drain from the 
unit, absent other forces, and exposure to these residual liquids is 
therefore not likely.
    As discussed in the next section, EPA has adopted an approach based 
on whether free liquids are present in the impoundment.
(2) What does it mean to contain liquid?
    The proposal explained that under the existing regulations, EPA 
determined whether an impoundment ``contains liquids'' by reference to 
a combination of the dictionary definition of ``contains,'' and the 
dewatering standard in Sec.  257.102(d)(2)(i). In essence, if liquids 
are present in an impoundment, the unit ``contains liquid.'' However, 
EPA considers a unit that met the performance standard in

[[Page 38989]]

Sec.  257.102(d)(2)(i) to have been dewatered. Several commenters 
supported this proposal.
    However, numerous other commenters raised concerns about relying on 
the plain language meaning of the phrase. For example, some commenters 
stated that all units contain some liquid, explaining that a landfill 
``contains'' rain after a heavy rainfall event. Similarly, a commenter 
argued that that under EPA's interpretation, a fully closed unit with 
ponded water on the cover resulting from precipitation or from fugitive 
dust control activities, and closed units with an engineered capability 
to impound water atop their covers would potentially be subject to the 
CCR regulations. The commenter stated that in all of these cases, the 
ponded water would seem to pose no risk.
    Commenters also separately questioned whether EPA had real risk 
concerns from units that contained ``any amount'' of liquid. For 
example, one commenter asserted that EPA has not demonstrated that 
units with any amount of water, no matter how small an amount or 
without regard to whether the liquid is separable from the CCR will 
present sufficient risks to warrant regulation under RCRA section 
4004(a). This commenter contended that EPA cannot rely on the 2014 Risk 
Assessment to support regulating such units because the assessment 
showed only that surface impoundments with a hydraulic head exceed that 
risk threshold. Several of these commenters recommended that EPA 
regulate based on whether the impoundment contains free liquids rather 
than liquids.
    Another commenter raised concern that relying on the plain language 
meaning would present a number of technical challenges. These included 
how owners can determine whether a previously closed and dewatered 
surface impoundment at an active (or inactive) facility still contains 
``liquids.'' The commenter explained that in some cases, State 
regulators confirmed that a site no longer had the capacity to impound 
water and therefore indicated that the site was no longer subject to 
the State's dam safety and impoundment rules. The commenter also asked 
whether EPA would accept use of the paint filter test, the detection of 
water in piezometers, or some other method to determine whether 
sufficient separable porewater is present for an impoundment to be 
considered to ``contain liquids.'' The commenter also asked what kinds 
of samples would be required--individual or composite--as well as how 
many and at what locations, to determine if an impoundment ``contains 
liquids.'' The commenter believed these questions need to be resolved 
in the numerous situations in which a formerly closed impoundment may 
contain some porewater as a result of periodic rainfall infiltration 
but is not in contact with the uppermost aquifer.
    By contrast commenters generally supported reliance on Sec.  
257.102(d)(2)(i) to determine whether a unit contains liquid; although 
they disagreed over what that provision requires. Several commenters 
agreed with the proposal's explanation of these existing closure 
requirements, stating that the discussion was fully consistent with 
EPA's long-held position under the largely identical hazardous waste 
regulations, citing to EPA documents from 1982 and 1988.
    But numerous other commenters argued that EPA had misinterpreted 
Sec.  257.102(d)(2)(i), and consequently was proposing to regulate 
impoundments that the commenters believed had been dewatered, and 
therefore posed little risk. According to these commenters, Sec.  
257.102(d)(2)(i) does not require the elimination of all liquids, or 
even all free liquids, but only requires the removal of liquid wastes 
to the extent necessary to support the cover system. These commenters 
also contended that ``the plain language of the 2015 CCR Rule does not 
require facilities to address groundwater as part of the closure 
performance standards under 40 CFR 257.102(d),'' based in part on the 
claim that regulatory definition of free liquids does not encompass 
groundwater. These commenters urged EPA adopt the same approach to 
determining whether an impoundment contains liquid.
    Several commenters also raised concern that the proposal failed to 
explain or provide clear guidance on how much water an impoundment must 
contain to be regulated as a legacy impoundment under the 2023 proposed 
rule. Many of these commenters requested EPA to clearly define a 
reasonable threshold associated with what it means to ``contain 
liquids,'' to aid the regulated community in determining when the 
performance standard has been met. One commenter noted that the Agency 
had attempted to fix this problem by relying on the closure standard in 
Sec.  257.102(d)(2)(i), which requires the elimination of ``free 
liquids,'' but the commenter considered this approach to be 
insufficient because EPA had not articulated how to determine whether 
free liquids have been eliminated.
    The final rule largely adopts the approach laid out in the 
proposal, relying on a combination of the plain language meaning of the 
phrase and the performance standard in Sec.  257.102(d)(2)(i) to 
determine whether an impoundment ``contains liquid.'' Under the 
ordinary meaning, an impoundment ``contains liquid'' if liquid is 
present in the impoundment, even if the impoundment does not prevent 
the liquid from migrating out of the impoundment. In other words, it 
``contains'' water if it has water within it. See, USWAG, supra at 454 
n. 23 (``The EPA's regulatory definition of ``impoundment'' is 
consistent with the dictionary definition of the verb ``impound,'' 
which manifests continuing action,'' citing Impound, Webster's Third 
New International Dictionary 1136 (3d ed. 1993) (``[T]o confine or 
store (water)[.]'')). Accordingly, under the final rule, if liquids are 
present in the unit, it will be considered to contain liquids, unless 
the facility can demonstrate that free liquids have been eliminated. 
Simply put, if a facility can document that free liquids were 
permanently eliminated prior to October 19, 2015, the unit will not be 
considered a legacy impoundment.
    Relying on Sec.  257.102(d)(2)(i) in this context is reasonable and 
protective. Both the definition of an inactive CCR surface impoundment 
and the closure performance standard are designed to address the same 
issues (the presence or removal of liquid wastes) and are designed for 
the same purpose (to ensure the risks from the co-management of CCR and 
liquid are adequately addressed). Once the free liquids have been 
eliminated from the impoundment, any remaining liquids do not present a 
reasonable probability of contaminating the aquifer. Thus, EPA does not 
intend an operator to removal all moisture from an impoundment, but 
only the free liquids required under Sec.  257.102(d)(2)(i), because of 
free liquids' contribution to risk.
    Contrary to some commenters' claims, the existing text in Sec.  
257.102(d)(2)(i) requires a facility to eliminate both the standing 
liquid in the surface of the impoundment and all readily separable 
porewater in any sediment located in the base of the impoundment. Free 
liquids are currently defined at Sec.  257.53 to mean ``liquids that 
readily separate from the solid portion of a waste under ambient 
temperature and pressure.'' This definition encompasses both standing 
liquids in the impoundment as well as any readily separable porewater 
(i.e., porewater that readily separates under ambient temperature and 
pressure) in any sediment or CCR. As EPA explained in the proposal, the 
existing regulation does not differentiate between the sources of the 
liquid in the

[[Page 38990]]

impoundment (e.g., surface water infiltration, sluice water 
intentionally added, groundwater intrusion). This is further supported 
by the fact that the performance standard at Sec.  257.102(d)(2)(i) was 
modeled on the regulations that apply to interim status hazardous waste 
surface impoundments, which are codified at Sec.  265.228(a)(2)(i). 
EPA's guidance on these interim status regulations clarifies that these 
regulations require both the removal of standing liquids in the 
impoundment and sediment dewatering. See, ``Closure of Hazardous Waste 
Surface Impoundments,'' publication number SW-873, September 1982. EPA 
previously discussed the subtitle C regulations at length beginning on 
page 29 in the Final Decision on Request For Extension of Closure Date 
Submitted by Gavin Power, LLC, 87 FR 72989 (November 15, 2022), as well 
as in the associated Response to Comments document located in the 
docket.\47\ And the definition of liquid included in this final rule 
removes any misunderstanding.
---------------------------------------------------------------------------

    \47\ The Final Decision and Response to Comments documents can 
be found in the docket for that action. See docket items EPA-HQ-
OLEM-2021-0590-0100 and EPA-HQ-OLEM-2021-0590-0099, respectively.
---------------------------------------------------------------------------

    The commenters are also mistaken that the existing regulation only 
requires the elimination of free liquids to the extent necessary to 
support the unit's final cover system, The provision does not state 
that the facility must ``eliminate free liquids to the extent necessary 
to support the final cover system,'' or anything comparable. Given that 
Sec.  257.102(d)(2)(ii) does specify that ``waste must be stabilized 
sufficient to support the final cover system,'' the absence of any 
similar text in paragraph (d)(2)(i) is dispositive. Compare Sec.  
257.102(d)(2)(i) and (ii).
    EPA disagrees that it is not taking into account whether the water 
in the unit poses risk. And for the same reasons EPA disagrees that it 
has failed to demonstrate that the units subject to regulation under 
this rule warrant regulation under RCRA section 4004(a).
    Impoundments with free liquids do in fact pose significant risk for 
the reasons discussed above. In the proposal, EPA discussed two 
examples of units that still ``contain liquids'': (1) A unit 
constructed such that the CCR in the unit was continually saturated by 
water flowing freely through the unlined impoundment; and (2) Where the 
facility has removed only the standing water from the impoundment. As 
EPA explained, as a purely factual matter, a surface impoundment that 
has only decanted the surface water would normally still contain free 
liquids if the waste in the unit was still saturated with water. 
Neither of these examples--which in actuality, likely represent the 
overwhelming majority of legacy impoundments subject to the final 
rule--have eliminated free liquids or involve trivial amounts of water. 
As explained in the preceding sections, such impoundments still contain 
hydraulic head and are otherwise essentially indistinguishable from the 
impoundments described in the 2015 CCR Rule preamble and modeled in the 
2014 Risk Assessment. And as EPA explained in the proposal, these units 
retain the conditions that cause a heightened risk of contaminating the 
aquifer. That is true even if the unit is considered ``closed'' under 
State law, is in the process of closing, or at some subsequent point, 
the unit is fully dewatered and no longer contains liquid.
    Moreover, as several commenters confirmed, it has apparently been a 
common practice to maintain CCR impoundments in a dewatered state. Even 
assuming these commenters meant that they had done more than merely 
remove the standing water, which seems unlikely given their comments on 
Sec.  257.102(d)(2)(i), without an effective cover system many 
``dewatered'' impoundments can nevertheless contain significant volumes 
of water simply as a consequence of the amount of precipitation that 
continually percolates through the unit. Based on an online USGS 
Rainfall Calculator Tool,\48\ the example unit will receive a total of 
27,154 gallons of water per acre during a single 1-inch rainfall event. 
Taking that a step further, a 50-acre impoundment in Atlanta, Georgia 
typically receives an average of 50 inches of rain a year, which 
equates, on a yearly average, to 67,885,000 gallons of water per 
year.\49\ In the absence of any action taken to remove the water, over 
time it will continue to accumulate in the unit.
---------------------------------------------------------------------------

    \48\ Found at https://www.usgs.gov/tools/usgs-rainfall-calculator. Found at https://www.usgs.gov/tools/usgs-rainfall-calculator.
    \49\ Based on 30-year average rainfall from National Weather 
Service data.
---------------------------------------------------------------------------

    Thus, in many areas of the country (e.g., the Southeast), CCR 
surface impoundments without an effective cover system may contain free 
liquids and meet the definition of a legacy impoundment due to the 
amount of annual rainfall.\50\ But this approach is intended to also 
clarify that contrary to the commenters' contention, a unit whose 
periodic rainfall does not result in free liquids (e.g., is readily 
absorbed into the CCR) would not be regulated as a legacy CCR surface 
impoundment.
---------------------------------------------------------------------------

    \50\ The frequency and severity of future rainfall events may be 
amplified by the effects of climate change. On average this would 
result in more water percolating through, and accumulating in, 
legacy CCR surface impoundments, which may further increase the risk 
of these units contaminating their underlying aquifers. More 
frequent and more severe rainfall events may also increase the risk 
that legacy CCR impoundments flood, overtop, and experience 
structural failures leading to potentially catastrophic releases of 
CCR into the surrounding environment. Many legacy CCR surface 
impoundments are located in 100-year floodplains which suggests that 
they are particularly vulnerable to rainfall driven flooding. Unit V 
of this preamble and the RIA accompanying this final rule describe 
this scenario in more detail.
---------------------------------------------------------------------------

    Finally, with respect to the small number of units that may have 
been completely dewatered after October 19, 2015, these units likely 
pose significant (and unacceptable) risks to human health and the 
environment that warrant regulation under RCRA section 4004(a), based 
solely on the expected presence of contamination that occurred while 
the impoundment was operating. See Unit III.A.2 of this preamble.
    This approach also largely addresses commenters' request for a 
clear standard, and many of their technical concerns. For example, the 
clarification that EPA is concerned with the presence of readily 
separable porewater, (that is, free liquids), which can be easily 
verified by technical equipment such as piezometers, thus resolves the 
commenters' concern that that porewater may be difficult to measure as 
it is held in the interstices or pore spaces between particles of soil, 
sediment, and/or CCR material and may not flow readily or be easily 
quantified using field or laboratory methods. EPA has also developed a 
memorandum describing the current methods and tools that are available 
to determine whether free liquids have been eliminated, which is 
available in the docket for this rulemaking. EPA has provided a brief 
summary of the memorandum in the next four paragraphs below.
    Many of the tools and methods to identify and eliminate free 
liquids are already widely used by industry to investigate and close 
surface impoundments. For example, tools currently used to identify 
free liquids include soil borings and cone penetrometers to map the 
stratigraphy of the CCR unit and characterize the geotechnical and 
hydraulic properties of the various CCR layers, as well as the 
installation of traditional piezometers, monitoring wells and vibrating 
wire piezometers to monitor pore pressures and water levels. Properly 
constructed

[[Page 38991]]

wells and piezometers screened in the appropriate locations and depths 
have a prominent role in networks of instruments used to assess free 
liquids, as their design directly measures water levels under ambient 
conditions. Fundamentally, water levels in properly constructed and 
developed wells and piezometers are indicative of free liquids at that 
location. Conversely, networks of spatially discretized wells and 
piezometers can be used as part of a program to determine or confirm 
that free liquids no longer exist.
    Similarly, tools and methods to eliminate free liquids within the 
CCR, such as rim ditches, underdrain systems, pumping wells, manifolded 
extraction wellpoints, etc., are also currently widely employed by 
industry. These elimination technologies can also provide diagnostic 
and confirmatory insights into the presence and nature of free liquids 
at a given CCR unit, e.g., rim ditches and open excavations enable 
direct observation of free liquids.
    EPA recommends that a demonstration of whether free liquids are 
present rely on a holistic evaluation of all information collected from 
site-wide monitoring networks (e.g., piezometers and vibrating wire 
piezometers), as well as data collected from actual dewatering efforts. 
EPA further recommends that monitoring networks include points of 
sufficient density to independently verify dewatering performance 
determined from implementation of elimination technologies.
    The memorandum also provides general guidance on considerations for 
developing successful site-specific strategies and approaches to 
identify, measure, monitor and eliminate free liquids. The elimination 
of free liquids relies on a well resolved understanding of the 
character and variability of the site-specific geology and hydrology, 
as well as the CCR materials themselves. Such information is frequently 
compiled into a Site Conceptual Model (CSM), and the memorandum also 
discusses some considerations related to the elements needed to 
construct a CSM if one does not already exist, or to augment a weak or 
poorly resolved CSM.
    EPA has adopted this approach rather than the commenters' 
suggestion to define a legacy CCR surface impoundment as a CCR surface 
impoundment that ``contains CCR and free liquids''--even though EPA 
expects the effect will be the same in almost all cases--because it 
represents the best balance of several competing considerations. First 
reliance on the broad dictionary definition is the most protective 
because all liquids have the potential to become the free liquids that 
create leachate and contribute to hydraulic head. This approach also 
maintains consistency with the existing definition of an inactive CCR 
surface impoundment.
    At the same time, EPA acknowledges that once the free liquids have 
been eliminated from the impoundment, any remaining liquids typically 
do not present a reasonable probability of contaminating the aquifer. 
EPA is also mindful of not establishing criteria that blur the lines 
between landfills and impoundments, EPA agrees with commenters that it 
would not be appropriate to designate a CCR landfill as a CCR surface 
impoundment based solely on periodic rainfall that is readily absorbed 
into the CCR and does not result in free liquids.
    The regulation reflects this balance by placing the burden on the 
owner or operator to demonstrate that the standard in in Sec.  
257.102(d)(2)(i) has been met. In other words, the absence of free 
liquids is an affirmative defense, and therefore any uncertainty as to 
whether the standard in Sec.  257.102(d)(2)(i) has been met is to be 
construed in favor of regulation because of the risks of environmental 
harm from free liquids in contact with CCR.
    Although, consistent with the 2015 CCR Rule, EPA is not requiring 
facilities to post documentation to demonstrate that no legacy 
impoundment is present at the site, EPA recommends that facilities 
develop and retain records to support any determination that a 
particular unit meets this exception. Finally, as discussed in Unit 
III.B.2.b.i of this preamble, EPA has provided additional time to allow 
a facility to determine that it has eliminated free liquids as part of 
its applicability report.
(3) Whether the Proposal Reflected a ``New'' Interpretation
    To support their claim that EPA had adopted new definitions of 
``liquid'', ``CCR surface impoundment'' and ``inactive CCR surface 
impoundment,'' a number of the commenters identified aspects of the 
2015 CCR Rule or preamble that they believe to be inconsistent with the 
May 2023 proposed rule preamble. First, several of these commenters 
claimed that statements in the proposed rule are inconsistent with the 
requirement in the existing definition of a CCR surface impoundment 
that the unit must be ``designed to hold an accumulation of CCR and 
liquids.'' 40 CFR 257.53. For example, some commenters stated that an 
impoundment that was dewatered and closed or is otherwise maintained so 
as not to impound liquids is no longer ``designed to hold an 
accumulation of CCR and liquids,'' and therefore, cannot be considered 
an inactive or legacy impoundment. Several commenters also claimed that 
the 2015 CCR Rule preamble, explained that the phrase, ``designed to 
hold an accumulation of CCR and liquids,'' means only units that 
``contain a large amount of CCR managed with water, under a hydraulic 
head that promotes the rapid leaching of contaminants.'' According to 
these commenters, although a dewatered or closed impoundment may 
``contain liquid'' as EPA defined it in the May 2023 proposal, no 
hydraulic head would be present. Or as one commenter stated, ``The 
Proposed Rule definition of liquids was expanded to include sources of 
water that are not demonstrated to be contributing to hydraulic head, 
or creating the potential for impoundment failure and spread of 
contaminated water.'' These commenters argue that facilities had relied 
on this guidance in good faith, and that ``simply citing the dictionary 
definitions of a `liquid' and 'contains' eight years after the 2015 CCR 
Rule published and without context is not a sufficient rationale or 
appropriate.''
    Several of these same commenters raised concern that EPA was 
proposing to regulate units that do not present the same risks on which 
the original rule was based. These commenters stated that in 2015 EPA 
did not strictly interpret ``liquids'' as precipitation, porewater, or 
groundwater without considering the associated force of liquids on the 
unit's embankment. According to the commenters, the 2015 CCR Rule was 
based on--and the current rulemaking should continue to be concerned 
with only--``the risk of excessive hydraulic head and the potential for 
structural failure of embankments from impounded water.'' The 
commenters further stated that the maintenance of CCR impoundments in a 
dewatered state significantly reduces the risk of structural failure, 
reduces the contact time with larger quantities of CCR, and reduces 
constituent concentrations and overall risk of impact to groundwater.
    Other commenters pointed to statements in the 2015 CCR Rule 
preamble that EPA did not intend the term ``inactive impoundments'' to 
include units that are closed, or to require closed units to reclose. 
Several of these commenters quoted the following discussion:

EPA did not propose to require ``closed'' surface impoundments to 
``reclose.'' Nor did

[[Page 38992]]

EPA intend, as the same commenters claim, that ``literally hundreds 
of previously closed. . .surface impoundments--many of which were 
properly closed decades ago under state solid waste programs, have 
changed owners, and now have structures built on top of them--would 
be considered active CCR units.'' Accordingly, the final rule does 
not impose any requirements on any CCR surface impoundments that 
have in fact ``closed'' before the rule's effective date--i.e., 
those that no longer contain water and can no longer impound liquid.

80 FR 21343.

    Another commenter asserted that based on the proposal's ``strict 
interpretation,'' all CCR landfills and all CCRMU would 
(inappropriately) be considered inactive or legacy CCR surface 
impoundments. As the commenter explained, a CCR landfill could contain 
liquids, especially after heavy rainfall, but as it was not designed to 
hold an accumulation of CCR and liquid it is not a CCR surface 
impoundment.
    A number of commenters also argued that the interpretation in the 
proposal of ``contains liquids'' is inconsistent with the decision in 
2015 to define sand and gravel pits as a CCR landfill. According to the 
commenters, if EPA intended inactive CCR surface impoundments to 
broadly encompass CCR in contact with groundwater, without hydraulic 
head, sand and gravel pits would have instead been added to the 
definition of CCR surface impoundment. The commenters base this on 
EPA's statement in the proposed rule that ``the damage from the 
placement of CCR in sand and gravel pits was almost always associated 
with CCR being placed in contact with water, which indicated that the 
placement of CCR in contact with water can lead to higher risks than 
from dry disposal.'' See, 80 FR 32010.
    Finally, a commenter raised concern that owners of inactive 
facilities that dewatered a CCR surface impoundment before October 19, 
2015, but completed the removal of CCR at some time after October 19, 
2015, could be subject to the CCR legacy rules because of what the 
commenter characterizes as the modification to the definitions of 
liquid and contains. This commenter also raised concern that some 
former coal-fired power plant properties were sold based on EPA's prior 
guidance that dewatered surface impoundments were not regulated, and 
asked whether these non-utilities will be required to comply with the 
documentation requirements.
    As discussed above, this final rule defines a legacy CCR surface 
impoundment as a CCR surface impoundment at an inactive facility that 
``contains both CCR and liquid,'' as EPA discussed that phrase in the 
proposal. EPA continues to believe that the appropriate construction of 
the phrase is to rely on its plain language meaning, consistent with 
the ordinary dictionary definitions those terms, in combination with 
the dewatering standard in Sec.  257.102(d)(2)(i). EPA is also 
promulgating a definition of this term in this final rule. As discussed 
above, some commenters have asserted that this definition is ``new.'' 
EPA disagrees. Regardless, even if it were new, it is permissible for 
EPA to define the term here in this rulemaking--EPA is not bound to any 
prior definition, and fully explained its rationale for the definition 
herein. In addition, the definition of liquids is not in any way 
inconsistent with other definitions in Sec.  257.53 or any other 
provisions from the 2015 CCR Rule.
    EPA agrees that a legacy CCR surface impoundment must meet the 
existing definition of a CCR surface impoundment in Sec.  257.53. That 
definition contains three criteria: (1) The unit must be ``a natural 
topographic depression, manmade excavation or diked area;'' (2) The 
unit must be ``designed to hold an accumulation of CCR and liquid;'' 
and (3) The unit ``treats, stores or disposes of CCR.'' 40 CFR 257.53. 
None of these require the presence of a particular amount of water or 
hydraulic head--or indeed any. Rather, the unit must be ``designed''--
that is, intended to--hold an accumulation of CCR and liquid. Although 
EPA expected that, based on its understanding of the utilities' current 
management practices, water would be present as a consequence of the 
treatment, storage, or disposal occurring in the unit, nothing in the 
text of the definition requires it, let alone requires a minimum 
amount. The requirement that liquid actually be present in the unit 
appears in the definition of an ``inactive surface impoundment'' (or 
``legacy CCR surface impoundment''), which as discussed, requires that 
the unit ``contains both CCR and liquids.'' 40 CFR 257.53.
    With this understanding, EPA disagrees with the commenter who 
asserted that based on the proposal's ``strict interpretation,'' all 
CCR landfills and all CCRMU would be considered inactive or legacy CCR 
surface impoundments. The commenter explained that, for example, a CCR 
landfill could contain liquids, especially after heavy rainfall, and 
the commenter believed that the construction of the regulation outlined 
in the proposal would mean that this unit would be classified as a CCR 
surface impoundment even though the unit was not ``designed to hold an 
accumulation of both CCR and liquid.'' EPA agrees that a unit that 
meets the definition of a CCR landfill would not become a CCR surface 
impoundment merely because it contained liquid; as the commenter noted, 
such a unit would not have been ``designed to hold an accumulation of 
both CCR and liquid.'' Ordinarily there should be clear indications 
that the unit was not intended or designed to function as an 
impoundment; for example, if the facility placed only dry CCR into a 
unit, or had designed or constructed the unit as a CCR landfill (e.g., 
it was constructed or operated with a leachate collection and removal 
system that meets the requirements of Sec.  257.70(d)). It was for this 
reason that EPA included sand and gravel pits within the definition of 
a CCR landfill; all of those instances involve the placement of 
exclusively dry CCR into the sand and gravel pits with no indication 
that they were designed to hold liquids.
    For the same reason, EPA disagrees that an impoundment that has 
been dewatered and closed or is otherwise now maintained so as not to 
impound liquids should no longer be considered ``designed to hold an 
accumulation of CCR and liquids,'' and therefore, should not be 
considered an inactive or legacy impoundment. Just as a landfill would 
not suddenly become ``designed to hold an accumulation of both CCR and 
liquids'' based on the temporary presence of precipitation, removing 
liquids from a unit that was constructed as a surface impoundment and 
that operated as a surface impoundment by managing both CCR and liquids 
for decades, does not suddenly mean that the unit is no longer 
``designed to hold an accumulation of CCR and liquids.'' Even assuming 
all free liquids had been removed from the unit, which as discussed 
below is unlikely, the subsequent removal of liquids as part of closing 
the unit does not change either the original design or use of the unit; 
the commenters do not intend to retrofit the unit for subsequent use as 
a landfill, but are merely in the process of complying with the 
requirements applicable to the closure of CCR surface impoundments. Nor 
does the subsequent dewatering change the present risks arising from 
the original design and long-term operation of the unit as an 
impoundment. To avoid any confusion on this point, EPA has deleted the 
phrase ``which is'' from the existing definition of a CCR surface 
impoundment.
    EPA also disagrees that the proposed (and now final rule) expanded 
the existing definition of a CCR surface impoundment--either by 
regulating

[[Page 38993]]

different kinds of units as surface impoundments than are currently 
regulated as surface impoundments, or by regulating units that present 
substantially different kinds or level of risks. These commenters have 
misunderstood the 2015 CCR Rule and preamble.
    EPA did not limit surface impoundments to units ``containing a 
large amount of CCR managed with water, under a hydraulic head that 
promotes the rapid leaching of contaminants.'' The definition of a CCR 
impoundment is discussed in the 2015 preamble at 80 FR 21357-21358. 
Reading the discussion as a whole, rather than the single sentence from 
the preamble that the commenters reference, clearly demonstrates that 
the 2015 CCR Rule was concerned with more than the risks associated 
with the force of impounded water on the embankment structure and 
included the risks of contamination when water travels from the 
impoundment to the surrounding are, and that EPA did not limit the CCR 
surface impoundments regulated under the 2015 CCR Rule to those that 
contain a particular amount of water or degree of hydraulic head.
    It is clear from the complete discussion that what determines 
whether a unit is considered a CCR surface impoundment are the three 
criteria \51\ (discussed above) actually in Sec.  257.53, rather than a 
finding that the particular unit ``contain[s] a large amount of CCR 
managed with water, under a hydraulic head that promotes the rapid 
leaching of contaminants.''
---------------------------------------------------------------------------

    \51\ The existing definition of a CCR surface impoundment 
contains three criteria: (1) The unit must be ``a natural 
topographic depression, manmade excavation or diked area;'' (2) The 
unit must be ``designed to hold an accumulation of CCR and liquid;'' 
and (3) The unit must ``treat[ ], store[ ] or dispose[ ] of CCR.'' 
40 CFR 257.53.
---------------------------------------------------------------------------

    In addition, the critical issue in crafting the definition was the 
quantity of CCR in the unit, not the quantity of water. Thus EPA 
explained that it was modifying the proposed definition to address 
concerns that it would capture ponds that contain only de minimis 
levels of CCR, because it agreed with commenters that the rule as 
proposed could inadvertently capture units that present significantly 
lower risks, such as process water or cooling water ponds that 
``although they will accumulate any trace amounts of CCR that are 
present, they will not contain the significant quantities that give 
rise to the risks modeled in EPA's assessment.'' 80 FR 21357. EPA then 
stated that by contrast, ``units that are designed to hold an 
accumulation of CCR and in which treatment, storage, or disposal occurs 
will contain substantial amounts of CCR and consequently are a 
potentially significant source of contaminants.'' Id. (Emphasis added).
    These points are best illustrated by the specific examples 
discussed in the preamble of the 2015 CCR Rule. First, in each example 
EPA explained whether the units would be considered CCR surface 
impoundments exclusively by reference to the criteria in the 
regulation. 80 FR 21357. Second, the units in each of the examples 
contained varying degrees of water and therefore hydraulic head. The 
final example was a diked area in which wet CCR is placed in order to 
remove the water for future transport to a CCR landfill or beneficial 
use. EPA explained that:

[t]he unit is accumulating CCR, while allowing for the evaporation 
or removal of liquid (no free liquids) to facilitate transport to a 
CCR landfill or for beneficial use. In this instance, the unit again 
meets all three definition criteria, it is a diked area (i.e., there 
is an embankment), it is accumulating CCR for ultimate disposal or 
beneficial use; and it is removing any free liquids, (i.e., 
treatment). As such, this unit would meet the definition of CCR 
surface impoundment.

80 FR 21357. The impoundment in this example contains far lower amounts 
of liquid than would be found in an operating impoundment because it is 
used to remove liquid from CCR. In essence such units would likely not 
contain significantly more liquid than the partially dewatered 
impoundments that the commenters now claim are exempt based on their 
supposed lack of a hydraulic head. 80 FR 21357-21358.
    More to the point, the units that the commenters argue should be 
exempt do still contain a hydraulic head ``that promotes the rapid 
leaching of contaminants'' and the consequent increased risks of 
leachate contaminating groundwater.
    Based on their comments on the closure performance standards, what 
these commenters mean by ``dewatered'' is merely the removal of: (1) 
Only the standing liquid or the free liquid visible at the surface of 
the impoundment; or (2) Free liquids in the CCR only to the depth 
needed to safely work with heavy machinery and to expedite the closure 
process. Properly characterized, this is merely partial dewatering. As 
previously discussed, because they are not removing free liquids beyond 
this depth, this eliminates neither the ``liquid,'' the hydraulic head 
in the unit, or the conditions that create the heightened risk of 
leachate contaminating ground or surface water. Although this will 
reduce the hydraulic head, until the water is eliminated, gravity will 
continue to exert downward pressure on the saturated waste. Continued 
contact with free liquids will continue to cause metals and other 
constituents to leach from the CCR, and the downward pressure of the 
hydraulic head will continue to drive the leachate toward the bottom of 
the unit into the surrounding soil and/or into the aquifer, along with 
any CCR constituents that have leached from the waste.
    It is clear from the 2015 preamble that the situation described by 
the commenters is not what EPA intended when it explained that the 
regulations did not apply to ``closed'' units. In the paragraphs 
preceding the commenters' selective quotation, EPA defined inactive 
surface impoundments as ``those that contain both CCR and water, but no 
longer receive additional wastes.'' 80 FR 21343. EPA further explained 
that ``By contrast, a `closed' surface impoundment would no longer 
contain water, although it may continue to contain CCR (or other 
wastes), and would be capped or otherwise maintained.'' Id. (emphasis 
added). See also, Id. (3d col) (``Accordingly, the final rule does not 
impose any requirements on any CCR surface impoundments that have in 
fact `closed' before the rule's effective date--i.e., those that no 
longer contain water and can no longer impound liquid.'') (emphasis 
added). Note that EPA stated that a closed unit would not contain 
``water,'' without qualification or limitation. Nowhere in this 
discussion (or the rest of the preamble) did EPA distinguish between 
water, free water, porewater, or groundwater, or expressly suggest that 
any of those might appropriately remain in the unit after closure.
    EPA thus agrees that, as in the 2015 CCR Rule, ``an impoundment 
that no longer contains liquid prior to October 19, 2015'' would not be 
considered either an inactive impoundment or a legacy impoundment.\52\ 
EPA acknowledges that CCR surface impoundments that contained liquids 
prior to October 19, 2015, can still be associated with significant 
environmental and human health risks. As discussed in Unit III.A.1 of 
this preamble, many if not all of these impoundments lacked a composite 
liner system, and therefore likely leached contaminants into the soil 
and underlying aquifer during operation. Eliminating the liquid from 
the impoundment will not remediate these releases--which at some sites 
may be significant--although it may substantially reduce or eliminate a 
source of additional or continuing

[[Page 38994]]

contamination. And to the extent the unit lacks an effective cover 
system, the unit may still be leaching contaminants, albeit at a 
reduced rate. Consequently, although such units would not be considered 
inactive or legacy impoundments, some will be regulated as a CCR 
management unit, as described in the next section.
---------------------------------------------------------------------------

    \52\ EPA also discusses its interpretation of ``impound liquid'' 
in Unit III.B.2.g of this preamble.
---------------------------------------------------------------------------

    However, the proposal by some commenters to regulate any 
impoundment that has ever contained CCR and liquids would represent a 
significant expansion of the regulations, in that it would essentially 
capture every CCR surface impoundment that ever operated in the United 
States. To illustrate the potential implications of such a revision: 
approximately 533 surface impoundments and 239 landfills are regulated 
under the 2015 Rule. EPA estimates that as a consequence of this final 
rule, an additional 194 (legacy) surface impoundments will be 
regulated. By contrast, as one commenter calculated, approximately 
2,170 surface impoundments were operating in 1973 alone.\53\ EPA, 
however, is not prepared at this juncture to expand the regulation so 
dramatically without first obtaining at least some basic information 
about the kinds of sites that would be regulated. Instead, EPA is 
proceeding to address the effects of past CCR management one step at a 
time, and is focusing here on a narrower universe of regulated units.
---------------------------------------------------------------------------

    \53\ GenOn Comments at 5-6. Estimate based on the number of 
coal-fired generating units operating in 1973 according to the U.S. 
Energy Information Administration (1,839) and assuming 1.2 surface 
impoundments per plant, consistent with operations in 2010.
---------------------------------------------------------------------------

    The Agency is not required to address every aspect of a problem 
immediately; courts have long recognized that it can be appropriate to 
address complex problems in stages. This final rule expands oversight 
to approximately 194 legacy CCR surface impoundments, and as discussed 
in Unit III.C, closes gaps in the existing regulations that currently 
fail to require facilities to remediate known contamination resulting 
from the operation of their CCR units. EPA expects to shortly publish a 
final permit rule and to begin issuing permits to bring facilities into 
full compliance. While the Agency works to address the risks from this 
current universe, EPA will also continue to collect information to 
better understand the full extent of the potential problem posed by the 
universe of abandoned sites that remain unregulated. In the interim, 
authority under RCRA section 7003 and CERCLA section 106 remains 
available to address any imminent and substantial threats to human 
health or the environment that these unregulated sites may present. 42 
U.S.C. 6873 and 9606.
    EPA also agrees that as a consequence of the plain language meaning 
of the phrase ``contains liquid,'' the owners of inactive facilities 
that dewatered a CCR surface impoundment before October 19, 2015, but 
completed the removal of CCR at some time after October 19, 2015, would 
be subject to this final rule if only the standing water had been 
removed from the impoundment by this date. As EPA explained in the 
proposal, as a purely factual matter, a surface impoundment that has 
only removed visible surface water would normally still contain liquids 
if the waste lower in the unit was still saturated with water. However, 
this issue is also discussed further in the next section. Because the 
regulation applies exclusively to the current owners and operators, if 
such a facility had been sold to a non-utility, the new owner, rather 
than the previous owner, will be required to comply with the any 
applicable requirements.
(4) Adding a Definition to the Regulations
    As noted previously, EPA solicited comments on whether adopting a 
definition of ``liquids'' into part 257 would provide greater clarity. 
The preamble discussed various possible definitions, including from 
Merriam-Webster and a technical definition. The proposal also explained 
that the term ``liquids'' encompasses all the various types of liquid 
that may be present in a CCR unit, including water that was sluiced 
into the impoundment along with the CCR, precipitation, surface water, 
and groundwater that has migrated into the impoundment due to the 
construction of the unit, which may be found as free water or standing 
water ponded above the CCR or porewater intermingled with the CCR. 88 
FR 31992. Although there was widespread disagreement about what the 
definition should be, most commenters appeared to support including a 
definition in the regulations. Several commenters supported including a 
definition of ``liquids'' in the final rule to prevent future disputes 
over the meaning of the term. Some of these commenters stated that 
``given the clear, plain language of the CCR Rule's closure provisions 
and EPA's longstanding implementation of the regulations, codifying a 
regulatory definitions [sic] of the plain term `liquid(s)' should be 
unnecessary.'' However, the commenters also stated that ``in light of 
industry's apparent preference to litigate the reality that groundwater 
is liquid in favor of properly closing its leaking, unlined ponds, EPA 
should codify its longstanding, plain meaning definitions of key terms 
in the hope of avoiding unnecessary and costly future litigation and 
ensuring timely, proper closure.''
    By contrast several commenters opposed including a definition in 
the regulations, suggesting that EPA should instead continue to rely on 
how the commenters believed those terms have been used in the 2015 CCR 
Rule and historically applied in implementing RCRA requirements. Some 
of these commenters stated that EPA has not provided adequate notice to 
the public of a new regulatory definition of ``liquids,'' and claimed 
that EPA therefore could not adopt a regulatory definition of 
``liquids'' in a final rule. Finally, a commenter opposed adding a 
definition of ``liquids'' to the regulations, arguing that it would not 
change the definition of ``free liquids,'' which the commenter believes 
is a distinct, technical regulatory term that does not encompass 
groundwater, or the performance standard in Sec.  257.102(d)(2)(i), 
which, according to the commenter, only requires the removal of liquid 
wastes and stabilization of remaining wastes to support the cover 
system.
    Several commenters recommended that in the absence of a statutory 
definition of ``liquid(s)'' and consistent with the CCR regulatory 
definition of ``free liquids'' and EPA's longstanding implementation of 
the predecessor hazardous waste closure regulations, EPA should codify 
a definition of ``liquid'' based on the dictionary definitions as set 
forth in the Proposed Rule. They also suggested that the definition 
should make clear that the term encompasses free water, porewater, 
standing water, and groundwater without regard to their source.
    Commenters also offered numerous alternatives. For example, several 
commenters offered technical definitions from various sources. One of 
those commenters raised concern that the technical definition discussed 
in the proposal had the potential to be confusing. According to this 
commenter, bulk particulate solids, such as fly ash, exhibit the 
physical properties of a liquid identified in the technical definition: 
specifically, dry fly ash flows when poured from container to container 
and conforms to the shape of a container--retaining its volume but not 
its shape. Instead, this commenter suggested that soil mechanics might 
provide useful information on which to base a definition.
    As noted above, numerous commenters also suggested that EPA should 
focus on ``free liquids'' rather

[[Page 38995]]

than ``liquids.'' Several of these commenters recommended that the 
final rule adopt the definition in 40 CFR 258.28(c)(1), which relies on 
the Paint Filter Liquids Test to determine whether liquids are present. 
The commenters recommended that the CCR and MSW landfill programs be 
consistent as both reside under RCRA subtitle D. However, one of these 
commenters also raised concern that it is unclear how far back in time 
this would reach and how EPA or the States would be expected to 
regulate inactive utilities that no longer exist but may have closed 
units that meet the definition. By contrast, other commenters raised 
concern about a definition that relied on the Paint Filter Liquids 
Test, stating that facilities had experienced difficulties implementing 
the test in the field.
    Another commenter explained that focusing on porewater, rather than 
the separable porewater covered by the definition of free liquids would 
cause technical difficulties. According to this commenter, porewater 
may be difficult to measure as it is held in the interstices or pore 
spaces between particles of soil, sediment, and/or CCR material and may 
not flow readily or be easily quantified using field or laboratory 
methods. Consequently, the commenter believed that it would not be 
feasible to identify whether liquids inclusive of all porewater 
(whether separable or not) were present in an impoundment or landfill 
closed prior to October 19, 2015, or in other words, to demonstrate the 
absence of liquids eight years ago.
    Similarly, one commenter stated that EPA should adopt a definition 
in the context of material in the ``liquid state'' such as free liquids 
and materials that behave as liquids and can be readily separated from 
the ``solid'' matrix and should not include those materials that are 
bound within the matrix and not readily separable. And another 
commenter recommended that EPA define a legacy impoundment based on the 
presence of free liquids and data to support that the free liquids have 
impacted groundwater.
    EPA continues to strongly believe that the plain text of the 
regulation clearly communicates the Agency's positions laid out above, 
and that in light of the dictionary definition a regulatory definition 
is not strictly necessary. However, in light of the different 
understanding of the regulations among commenters, EPA is incorporating 
the existing requirements into the definitions in Sec.  257.53. 
Accordingly, the final rule includes a definition of ``liquids'' based 
on the definition from Merriam-Webster discussed in the proposal. The 
new definition, codified at Sec.  257.53, provides that ``Liquids means 
any fluid (such as water) that has no independent shape but has a 
definite volume and does not expand indefinitely and that is only 
slightly compressible. This encompasses all of the various types of 
liquids that may be present in a CCR unit, including water that was 
sluiced into an impoundment along with CCR, precipitation, surface 
water, groundwater, and any other form of water that has migrated into 
the impoundment, which may be found as free water or standing water 
ponded above CCR or porewater intermingled with CCR.
    In addition, the final rule includes in Sec.  257.53 a definition 
of the phrase ``contains both CCR and liquids,'' consistent with the 
discussion above and in the proposal. The definition reflects both the 
dictionary definition of ``contains'' and EPA's explanation that it 
relies upon the closure standard in Sec.  257.102(d)(2)(i) to determine 
whether a unit contains liquids.
    The definition states that ``Contains both CCR and liquids means 
that both CCR and liquids are present in a CCR surface impoundment, 
except where the owner or operator demonstrates that the standard in 
Sec.  257.102(d)(2)(i) has been met.''
    These definitions reflect EPA's construction of the existing 
regulations. In addition, codifying these definitions definitively 
confirms that an impoundment saturated by groundwater or continually 
inundated by surface water is an inactive or legacy impoundment. It 
also provides greater clarity that all kinds of liquid are relevant to 
determining whether an impoundment is subject to part 257 and has 
properly closed.
    Consequently, EPA decided not to adopt either the technical 
definition of liquid discussed in the proposal or any of the suggested 
alternatives. EPA agreed that the technical definition in the proposal 
had the potential to be confusing given that fly ash can sometimes 
exhibit the physical properties of a liquid identified in the technical 
definition. While EPA also agrees that CCR is a porous material similar 
to soil, EPA did not adopt the commenter's suggestion to rely on soil 
physics to craft an alternative. CCR is not a soil, and EPA is 
concerned more with the hydraulic characterization of CCR that involves 
other considerations in addition to soil physics.
    EPA also chose not to adopt the definition in 40 CFR 258.28(c)(1), 
which relies on the Paint Filter Liquids Test, or to otherwise mandate 
reliance on the Paint Filter Liquids Test. First, a number of other 
commenters raised technical concerns about relying on this test in this 
context. In addition, EPA would not generally recommend using the Paint 
Filter Liquids Test in this context. There can be physical effects from 
obtaining the sample that could affect the representativeness of the 
sample (vibration, heat from the drilling bit, etc.) and that can 
result in false negatives. Consequently, although it might provide 
relevant information to confirm the presence of water in a sample, EPA 
does not generally consider the results to be sufficiently reliable to 
confirm the absence of free liquids.
    EPA disagrees that the public had insufficient notice of a 
potential definition. EPA explained the subjects and issues the agency 
would consider in reaching its decision, and provided examples of 
possible definitions. In general, to provide adequate notice an agency 
must ``provide sufficient factual detail and rationale for the rule to 
permit interested parties to comment meaningfully.'' Florida Power & 
Light Co. v. United States, 846 F.2d 765, 771 (D.C. Cir. 1988). As 
demonstrated in the preceding section, numerous other entities were 
able to effectively provide comments, for example raising concerns 
about the definitions discussed in the preamble, and offering potential 
alternatives. No commenter has indicated what further information is 
necessary to be able to comment effectively on the issue.
    EPA agrees that adopting these definitions will not change the 
performance standard in Sec.  257.102(d)(2)(i), but for very different 
reasons than those proffered by the commenters. Incorporating these 
definitions into the part 257 regulations merely reaffirms the plain 
language meaning of the term ``liquids,'' which, as previously 
explained, is the status quo. But because the term ``liquids'' is used 
in the definition of ``free liquids,'' defining liquids to expressly 
encompass all of the various types that may be present in a CCR unit, 
including groundwater, removes any misunderstanding that such liquids 
cannot be considered to be free liquids when they otherwise meet the 
definition, that is, they readily separate from the solid potion of CCR 
at ambient temperature and pressure.
    However, the commenters are correct that it will not address their 
misconstruction of Sec.  257.102(d)(2)(i), which attempts to limit the 
requirement based on text that does not appear in the provision. 
Further discussion of Sec.  257.102(d)(2)(i) can be found in Unit 
III.B.2.g.

[[Page 38996]]

    In conclusion, under this final rule the surface impoundments 
discussed in the proposal would still be considered legacy 
impoundments, as all would still contain free liquids. Specifically 
this includes (1) Any impoundment where, on or after October 19, 2015, 
water flowed or continues to flow through the impoundment, permeating 
the waste in the unit, such as where the base of the impoundment 
intersects with the groundwater; (2) A surface impoundment where only 
the surface water has been decanted; here too the impoundment would 
normally still contain free liquids if the waste in the unit was still 
saturated with water; and (3) Any impoundment that still contains free 
liquids: (a) even if it is considered ``closed'' under State law; (b) 
it is in the process of closing on the effective date of this rule; or 
(c) the unit has been fully dewatered and can no longer impound liquid 
only after October 19, 2015 (i.e., it contained free liquids on October 
19, 2015).
ii. What does it mean to ``contain'' CCR?
    In the proposal, EPA explained that under the existing regulation, 
an inactive CCR surface impoundment must contain CCR to be subject to 
the rule. 40 CFR 257.53. EPA further explained that it was not 
proposing to revise that aspect of the legacy impoundment definition. 
EPA proposed that, consequently, a legacy impoundment that had closed 
by removal in accordance with the performance standards in Sec.  
257.102(c) before October 19, 2015, would not be considered an inactive 
(and therefore not a legacy) CCR surface impoundment.
    EPA also proposed that an impoundment at an inactive facility that 
was still in the process of closing by removal on October 19, 2015, 
would be considered a legacy CCR surface impoundment subject to the 
final rule requirements. EPA proposed that facilities with such a unit 
would be required to certify and post documentation that they have met 
the existing standard for closure by removal in Sec.  257.102(c) on 
their CCR website (i.e., ``certification requirement''). However, if a 
facility could not demonstrate that the closed impoundment meets the 
existing performance standards in Sec.  257.102(c), the unit would be 
considered a legacy impoundment subject to the rule. EPA further 
explained that because the impoundment contained liquid and CCR on 
October 19, 2015, it would meet the definition of a legacy CCR surface 
impoundment, and that EPA had no basis to exempt it, because EPA had no 
factual basis to conclude that a legacy CCR surface impoundment that 
was in the process of closing posed no risk. However, EPA explained 
that depending on when the impoundment completed closure, some 
individual requirements may no longer be applicable to the legacy CCR 
surface impoundment (i.e., when the compliance date in the final rule 
falls after the date closure is completed for the impoundment).
    No commenter opposed the proposal to exclude impoundments that did 
not contain any CCR prior to the effective date of the 2015 CCR Rule, 
although several commenters believe that additional impoundments should 
also be excluded. For example, many commenters stated that EPA does not 
have jurisdiction under RCRA over impoundments from which all CCR was 
removed between October 19, 2015, and the effective date of this final 
rule. As one of these commenters explained:

    As proposed, a closed unit would still be regulated under the 
final rule if all CCR has been removed but groundwater monitoring 
shows exceedances of the groundwater protection standard 
constituents listed in Appendix IV. RCRA's juridical boundaries are 
exceeded under this interpretation. The USWAG decision explained 
that RCRA gives EPA the authority to regulate past disposal of CCR 
based on the continued presence of CCR. Once the CCR is removed, CCR 
is no longer disposed of, and EPA does not have the ability to 
regulate based on the previous existence of CCRs.

Commenters also provided examples of the type of facility they believe 
that EPA cannot regulate. For example, one commenter described a 
closure of three interconnected CCR surface impoundments associated 
with the Richard H Gorsuch Power Plant. According to the commenter,

the closure was permitted by the state of Ohio, along with a 
redesign of one of the impoundments to control stormwater runoff 
post-closure. The closure of these impoundments included dewatering 
and removal of all CCR materials to clean soil prior to filling with 
clean soil and grading. All CCR was transported to the associated 
off-site fly ash landfill. No groundwater monitoring was required, 
all the CCR was removed, and the site is adjacent to an existing 
RCRA corrective action (Union Carbide) with known groundwater 
impacts.

    Some of these commenters further stated that EPA cannot rely on any 
residual contamination left in groundwater to support jurisdiction 
because EPA has made clear that groundwater (as well as other 
environmental media containing contaminants) is not a solid waste. 
Finally, some commenters asserted that EPA has no data showing that 
there is a reasonable probability of adverse impact from historical CCR 
units that have been closed by removing the CCR, and as a consequence, 
EPA cannot regulate such units.
    By contrast, a number of commenters requested that EPA clarify that 
its statement in the Proposed Rule that EPA ``no longer has 
jurisdiction over a former unit that has closed by removal in 
accordance with Sec.  257.102(c)''--is based on the complete absence of 
CCR, and requires not only removal of CCR from and decontamination of 
the unit but completing all groundwater cleanup and other remedial 
measures and then adequately documenting, with at least two years of 
post-removal or decontamination groundwater monitoring, that GWPS are 
reliably achieved by removal prior to the effective date of the final 
rule.
    EPA disagrees that it lacks jurisdiction over a site at which the 
owner has removed CCR from the impoundment after October 19, 2015. Many 
of the commenters misunderstand the USWAG decision, as well as the 
legal structure applicable to these units.
    First, the USWAG decision did not limit EPA's authority to sites 
where CCR remains, but to sites where solid waste is present. See, 
USWAG, 901 F.3d at 440-441 (``Properly translated then, an open dump 
includes any facility (other than a sanitary landfill or hazardous 
waste disposal facility), where solid waste still ``is deposited,'' 
``is dumped,'' ``is spilled,'' ``is leaked,'' or ``is placed,'' 
regardless of when it might have originally been dropped off.'') 
(emphasis added).
    Second, in the example EPA presented in the proposal, even though 
the facility may have removed all CCR from the surface impoundment, 
solid waste still remains on site because groundwater monitoring 
continues to detect statistically significant levels of one or more 
Appendix IV constituents. These monitoring results demonstrate the 
continued presence of CCR leachate \54\--which is a solid waste under 
the definition in 42 U.S.C. 6903(27)--in groundwater, and, potentially, 
in soil at the site. As discussed in greater detail below, this is 
sufficient to demonstrate that EPA retains jurisdiction over the site, 
under the plain language of the statutory definitions of solid waste 
and disposal.
---------------------------------------------------------------------------

    \54\ Leachate is produced when liquids, such as rainwater or 
groundwater, percolate through wastes stored in a disposal unit. The 
resulting fluid will contain suspended components drawn from the 
original waste.
---------------------------------------------------------------------------

    EPA also considers that it has authority to regulate as part of 
this rule, sites similar to the one presented by the

[[Page 38997]]

commenter above. As discussed in more detail below, the rulemaking 
record supports a presumption that solid waste remains at the site, 
even assuming the facility had removed all CCR from the impoundment. 
The rulemaking record demonstrates the high likelihood that the 
impoundment will have leaked during its operation. As a consequence, at 
any site that closed without groundwater monitoring, such as the one 
described in the comment above, or that has not undertaken any 
remediation, there is every reason to believe that leachate (and, 
therefore, solid waste) will remain on site. In addition, the measures 
that facilities have described taking to remove all CCR from the 
impoundment would in fact leave CCR leachate remaining in soils at many 
sites.
(a) Definition of Solid Waste
    EPA's jurisdiction over sites at which CCR leachate remains is 
clear from the plain language of the statutory definitions of solid 
waste and disposal.
    Under the CCR regulations, the statutory definition of solid waste 
applies, rather than any of the various narrower subtitle C regulatory 
definitions in 40 CFR part 261. Section 257.53 specifically provides 
that ``Terms not defined by this section have the meaning given by 
RCRA.'' Part 257 does not include a definition of ``solid waste'' or 
``waste,'' which therefore takes the broader statutory definition of 
the term. See also the Sec.  257.53 definition of disposal, which 
references ``solid waste as defined in section 1004 (27) of the 
Resource Conservation and Recovery Act.''
    The subtitle C regulations are equally clear that they do not apply 
to subtitle D wastes. See, e.g., 40 CFR 260.1(a) (``This part provides 
definitions of terms, general standards, and overview information 
applicable to parts 260 through 265 and 268 of this chapter.''); Sec.  
261.1 (a) (``This part identifies those solid wastes which are subject 
to regulation as hazardous wastes under parts 262 through 265, 268, and 
parts 270, 271, and 124 of this chapter and which are subject to the 
notification requirements of section 3010 of RCRA.'').
    Under RCRA the term ``solid waste'' means:

any garbage, refuse, sludge from a waste treatment plant, water 
supply treatment plant, or air pollution control facility and other 
discarded materials, but does not include solid or dissolved 
material in domestic sewage, or solid or dissolved materials in 
irrigation return flows or industrial discharges which are point 
sources subject to permits under section 1342 of title 33, or 
source, special nuclear, or byproduct material as defined by the 
Atomic Energy Act of 1954, as amended (68 Stat. 923) [42 U.S.C. 2011 
et seq.].

42 U.S.C. 6903(27). The plain meaning of the word ``discarded'' in this 
definition is ``disposed of,'' ``thrown away,'' or ``abandoned.'' See, 
e.g., American Mining Congress v. U.S. EPA, 824 F.2d 1177, 1184 (D.C. 
Cir. 1987) (citations omitted) (``AMC I''); American Petroleum 
Institute v. EPA, 906 F.2d 729, 740-741 (D.C. Cir. 1990) (per curiam). 
Such materials are ``part of the waste disposal problem'' that Congress 
enacted RCRA to address. AMC I, 824 F.2d at 1193. In other words, under 
the statute if something has been disposed of, as that term is defined 
in the statute, it is a solid waste.\55\
---------------------------------------------------------------------------

    \55\ As EPA explained in the 2015 preamble, ``placement in a 
landfill or surface impoundment is prima facie evidence of 
discard.'' 80 FR 21348.
---------------------------------------------------------------------------

    Any CCR leachate left behind as soil and groundwater contamination 
after CCR removal would clearly constitute material that has been 
``abandoned'' or ``discarded'' and is thus subject to regulation under 
subtitle D without further activity. EPA has long considered material 
that has spilled or leaked onto the soil and not been cleaned up to 
have been ``abandoned'' or ``discarded.'' See, e.g., Chemical Waste 
Management v. EPA, 869 F.2d 1526, 1539 (D.C. Cir. 1989); Connecticut 
Coastal Fishermen Ass'n v. Remington Arms Co., 989 F. 2d 1305, (2d Cir 
1993).
    The conclusion that the CCR leachate contaminating soil and 
groundwater is a solid waste is also consistent with EPA's long-held 
interpretation (discussed at length in the 2015 CCR rule preamble) that 
leaking or passive migration of leachate constitutes the disposal of 
solid waste. 80 FR 21342-21347, quoting 43 FR 58954 (``This is an 
important issue, however, because some, and perhaps most, inactive 
facilities may still be `disposing of waste' within the meaning of that 
term in Section 1004(3) of RCRA. . . . Many inactive facilities may 
well be leaking solid or hazardous waste into groundwater and thus be 
`disposing' under RCRA.''). See also, e.g., In re Consolidated Land 
Disposal Litigation, 938 F2d 1386, 1388-1389 (D.C. Cir. 1991).
    And even under the narrower regulatory definition of solid waste in 
subtitle C, EPA has long considered leachate (i.e., the leaked 
constituents) from previously disposed hazardous wastes to be a 
hazardous (and therefore, solid) waste. See, e.g., 40 CFR 
261.3(c)(2)(i) (``any solid waste generated from the treatment, 
storage, or disposal of a hazardous waste, including any . . . leachate 
. . . is a hazardous waste.''). 45 FR 33096 (May 19, 1980) (``As a 
practical matter, this means that facilities which store, dispose of or 
treat hazardous waste must be considered hazardous waste management 
facilities for as long as they continue to contain hazardous waste and 
that any wastes removed from such facilities--including spills, 
discharges or leaks--must be managed as hazardous wastes.'')(emphasis 
added). See, also, Chemical Waste Management, 869 F.2d at 1539.
    Moreover, as discussed above, one factor the D.C. Circuit has 
considered in determining whether a substance is properly considered a 
waste is whether ``the materials are `part of the waste disposal 
problem' Congress intended to address in enacting RCRA.'' AMC I, 
quoting House Committee Report, H.R. Rep. No. 1491, 94th Cong., 2d 
Sess. at 2, U.S. Code Cong. & Admin. News 1976, p. 6240. If so, it 
falls under EPA's authority in RCRA to address. See, American Mining 
Congress v. EPA, 907 F.2d 1179, 1186-87 (D.C. Cir. 1990) (deferring to 
EPA's focus on potential environmental harm in determining whether 
material is discarded) (AMC II). The contamination from legacy 
impoundments (even when the CCR has been removed from the impoundment) 
remains a threat to human health and the environment that stemmed from 
discarded materials, and thus is ``part of the waste disposal problem'' 
RCRA was enacted to address.
    As discussed in more detail in Unit III.A.3, EPA estimates that 
groundwater contamination at sites with legacy impoundments could pose 
lifetime cancer risks from arsenic as high as 2 x 10-5 to 1 
x 10-5 (i.e., 2 to 100 cases of cancer for every 100,000 
individuals exposed), depending on the specific management practices 
and site conditions. In addition, EPA estimated noncancer risks well in 
excess of an HQ of one for a wide variety of CCR constituents, 
depending on the management practices and site conditions; for example, 
the high-end of noncancer risks for lithium ranged between two to 
three; for molybdenum up to an HQ of four; thallium up to an HQ of two, 
and for cobalt and mercury up to an HQ of 13 and five, respectively. 
Moreover, in the absence of any groundwater remediation, there is no 
reason to believe that the removal of CCR from the impoundment 
mitigates these risks. Although the unit may no longer continue to 
contribute additional contamination, removal of the CCR does not 
address the release of and risk from the metals or other CCR 
constituents in any contaminant plume.

[[Page 38998]]

    The leachate from a CCR surface impoundment or landfill is 
therefore unquestionably a solid waste under the broader statutory 
definition in 42 U.S.C. 6903(27). And to the extent the leachate 
remains in soil or groundwater, that is sufficient to support 
jurisdiction over that site, even though all CCR may have been removed 
from the disposal unit. The risks from the leachate-contaminated 
groundwater also clearly establish a reasonable probability of adverse 
impacts on health and the environment from legacy impoundments that 
have been closed by removing only the CCR.
    EPA disagrees with the commenters who stated that the Agency should 
not presume that there have been impacts to groundwater from an area 
where the ash has been fully removed, absent specific evidence to the 
contrary. The record from both the 2015 CCR Rule and the current 
rulemaking supports a strong presumption that solid waste remains on-
site at these facilities. As the D.C. Circuit noted, legacy 
impoundments have been shown to be even more likely to leak than units 
at utilities still in operation. 901 F.3d at 432.
    Data collected as part of the 2015 rulemaking shows that the 
majority of the older operating (pre-1994) waste units lack liners; 63% 
and 24% of older surface impoundments have either no liners or clay 
liners, respectively. 80 FR 21326. Thus far, no commenter has 
identified a legacy impoundment with a composite liner.
    Analysis of the information from the damage cases also demonstrates 
that unlined surface impoundments typically operate for 20 years before 
they begin to leak. Id. at 21326-21327. As discussed previously, 
commenters submitted data indicating that on average legacy 
impoundments are 55 years old. The following examples discussed in the 
2015 CCR rule preamble further demonstrate the high probability that 
legacy impoundments will have leaked, and that in the absence of 
remediation measures leachate is highly likely.
    In the wake of the 2008 TVA Kingston CCR spill, Illinois and North 
Carolina for the first time required utilities to install groundwater 
monitoring. Illinois required facilities to install groundwater 
monitoring downgradient from their surface impoundments. As a result, 
within only about two years, Illinois reported that seven facilities 
had detected instances of primary MCL exceedances, and five additional 
facilities had reported exceedances of secondary MCLs. The data for all 
12 sites were gathered from onsite; it appears none of these facilities 
had been required to monitor groundwater off-site, so whether the 
contamination had migrated off-site was unknown. Similarly, North 
Carolina required facilities to install additional down gradient wells. 
In January 2012, officials from the North Carolina Department of 
Environment and Natural Resources disclosed that elevated levels of 
metals were found in groundwater near surface impoundments at all the 
State's 14 coal-fired power plants. 80 FR 21455.
    It is also highly unlikely that removal of CCR would also have 
removed all areas affected by releases at many (if not most) sites. In 
their comments, facilities have described relying on visual inspection 
or in some cases microscopic inspection of soil material to determine 
whether all CCR have been removed from the impoundment. In such cases, 
the practical depth limit of such investigations is generally just 
beneath (e.g., a foot or less) the visually observed maximum depth of 
CCR. However, it is not likely this practice would be sufficient at 
many legacy sites to remove all areas affected by releases of CCR 
leachate.
    At a minimum, for units with bases above the groundwater, the soil 
column beneath the unit from the base of the unit to at least the depth 
of the lowest water levels recorded in the aquifer, would typically 
need to determine whether the zone of water table fluctuation 
constitutes a residual source and may be in need of corrective action. 
Concentrations of contaminants at this horizon could be significantly 
elevated. In a case where prior site assessment and groundwater 
monitoring activities have not resulted in a preexisting well network 
capable of making this determination it may be necessary to install 
additional wells or to assess groundwater.
    Moreover, in a unit constructed with CCR below the ambient 
groundwater, after decades of groundwater infiltration through the 
waste, the leachate generated would be expected to show elevated levels 
of CCR constituents of concern. This chemically altered leachate can 
interact with unsaturated or partially saturated soils beneath the CCR 
and can react with aquifer solids beneath the unit to form intermediate 
chemical compounds, some of which may be bound to the aquifer matrix in 
solid phases. Also, depending on the amount of groundwater recharge and 
infiltration directed through the unit, some downwardly infiltrating 
leachate is likely to reach the saturated zone where additional 
chemical reactions occur. Depending on the degree of disequilibrium 
with the ``ambient'' conditions such reactions can be significant and 
can also result in formation of mineral species that become temporarily 
immobilized at or beneath the water table as solid mineral phases by 
formation of mineral precipitates or simply adsorbed to the aquifer 
matrices by retardation processes. These intermediate transformation 
products may contain CCR constituents of concern as either major, minor 
or trace components of newly formed compounds. Depending on the aquifer 
chemistry, including redox state, pH, salinity, alkalinity, etc., some 
CCR constituents may remain mobile in groundwater and may continue to 
migrate downgradient of the unit. Consequently, in situations where the 
waste is below the water table, assessment efforts would generally need 
to penetrate a sufficient depth below the base of the waste or the 
lowest water levels in the aquifer, whichever is greater, to ensure 
that potential releases of leachate to the soil have been evaluated.
    Consequently, based on the practices that facilities have stated 
that they use to confirm that they have removed all CCR from a site, 
both leachate contaminated soil and groundwater would frequently be 
expected to remain on site even after CCR may have been entirely 
removed from the impoundment. The totality of the information in the 
record thus supports a presumption that solid waste remains on-site. 
Demonstrating compliance with Sec.  257.102(c) rebuts that presumption 
and documents that the site is no longer under RCRA's jurisdiction.
    EPA also disagrees that reliance on the residual contamination left 
in groundwater to support jurisdiction is precluded by EPA's prior 
statements that contaminated media are not solid wastes. These 
commenters are referring to EPA statements made in connection with the 
``contained in'' policy under the RCRA hazardous waste regulatory 
program. As an initial matter, the commenters have misunderstood the 
policy. The policy states only that with respect to contaminated soil 
or groundwater, the media itself-the soil or groundwater-is not a solid 
waste-even though it contains a hazardous waste. In other words, the 
contamination itself remains a solid waste, and therefore subject to 
EPA's jurisdiction. See, Chemical Waste Management v. EPA, 869 F.2d at 
1539 (upholding EPA interpretation that hazardous waste restrictions 
continue to apply to waste ``contained in soil or groundwater'' as 
``consistent with the derived-from and mixture rules,'' even though the 
rules by their terms do not apply to

[[Page 38999]]

contaminated soil or groundwater because they are not solid wastes).
    In any event, as discussed above, none of the regulations in 40 CFR 
parts 260-268, or 270 apply, except to the extent EPA incorporated them 
into part 257, subpart D. This also means that any Agency 
interpretations or policies adopted under those regulations, no matter 
how long-standing, do not automatically apply to CCR, which are 
regulated under part 257, subpart D. Moreover, the policies and/or 
interpretations the commenters identify were developed based on the 
text of particular statutory or regulatory provisions under subtitle C, 
as well as the larger statutory context in which those particular 
statutory or regulatory requirements operate (for example, corrective 
action obligations at hazardous waste treatment, storage, and disposal 
facilities). RCRA subtitles C and subtitle D differ greatly. For 
example, only under subtitle C did Congress expressly prohibit land 
disposal of hazardous wastes that do not meet treatment standards 
established in EPA regulations. 42 U.S.C. 6924(d), (g), (h), (m). 
Similarly, there is no analog under subtitle D to section 6925(j), 
which imposes detailed requirements on hazardous waste surface 
impoundments. It would therefore be inappropriate to simply adopt a 
particular interpretation or policy developed under the particular 
provisions of the RCRA subtitle C hazardous waste regulatory program 
into the CCR program without evaluating whether the policy or 
interpretation is consistent the statutory language in subtitle D or 
would achieve Congress's purposes or direction. Note that EPA explains 
above how its approach is consistent with subtitle D and the 
congressional scheme.
    Finally, it is important to note that EPA is not suggesting that 
the management of CCR leachate is now subject to the CCR regulations. 
EPA has jurisdiction over CCR leachate because the material is solid 
waste not because it is CCR. Under the existing regulations the 
definition of CCR does not include leachate. See, 40 CFR 257.53. EPA 
did not propose to amend this regulation and does not currently intend 
to do so.
(b) Exclusions
    Several commenters suggested a number of other exemptions. For 
example, one commenter suggested that the final rule exclude legacy 
impoundments that only contain de minimis quantities of CCR. According 
to the commenter, EPA's risk analysis from the 2015 CCR Rule supports 
the conclusion that up to 75,000 tons of CCR used as structural fill is 
generally safe. Therefore, the commenter recommended that inactive 
impoundments with 75,000 tons or less, be exempt from regulation. Other 
commenters urged EPA to clearly define what is meant by de minimis 
amounts of CCR in the context of legacy impoundments.
    Other commenters requested that EPA exempt any legacy CCR surface 
impoundments that met State requirements for clean closure. These 
commenters argue that EPA cannot expect utilities who have closed 
legacy impoundments under State guidelines prior to this rulemaking to 
meet a standard that did not exist at the time of closure. These 
commenters also asserted that by regulating such units EPA is 
effectively disregarding a qualified State's regulatory authority to 
approve closure under the regulations and programs available to them at 
the time.
    Other commenters suggested that EPA should allow facilities to 
certify that they had completed closure by removal in two additional 
situations. The first suggestion was to allow a facility to certify 
that it had complied with Sec.  257.102(c) based solely on 
documentation that the facility had removed all ash by the effective 
date of the 2015 CCR Rule, unless EPA or the facility also had evidence 
(e.g., from existing monitoring networks) of groundwater impacts that 
could impact human health or the environment. These commenters stated 
that EPA should not presume that there have been impacts to groundwater 
from an area where the ash has been fully removed years or even decades 
ago, absent specific evidence to the contrary. The second suggestion 
was that EPA exclude facilities that could certify and document that 
they have met the closure-in-place performance standards in Sec.  
257.102(d) by the effective date of this final rule. To support their 
proposal, the commenter noted that EPA has made it clear that the owner 
or operator of a CCR facility can close a CCR unit under either Sec.  
257.102 (c) or (d) and be in compliance with the Federal CCR 
regulations.
    Finally, EPA received a number of comments on the kind of 
documentation that a facility needed to support a determination that it 
had closed a legacy impoundment by removal in accordance with the 
standards in Sec.  257.102(c) prior to October 19, 2015. Some 
commenters requested that the final rule require facilities to post 
detailed documentation demonstrating compliance with Sec.  257.102(c). 
Other commenters, however, objected to any documentation requirements, 
asserting that it was inconsistent with EPA's treatment of similar 
facilities in 2015, who were not required to provide any compliance 
documentation of closure requirements. These commenters requested EPA 
to remove the requirements under Sec.  257.100(f)(1)(ii) and allow 
owners to make the closure determination.
(c) Final Requirements
    Consistent with the proposal, this final rule provides that an 
impoundment that contained CCR (and liquids) on or after October 19, 
2015 is subject to this rule. This means that if a facility closed a 
legacy CCR surface impoundment by removal before October 19, 2015, that 
site is not subject to this final rule. However, the final rule does 
not require such facilities to demonstrate that these units were closed 
``in accordance with the performance standards in Sec.  257.102(c).'' 
Under Sec.  257.102(c) closure is complete when all CCR has been 
removed from the CCR unit, any areas affected by releases from the CCR 
unit have been removed, and groundwater monitoring concentrations do 
not exceed the groundwater protection standard in Sec.  257.95(h) for 
Appendix IV constituents. The proposed rule incorrectly stated that EPA 
was proposing to impose a documentation requirement on these 
facilities. That statement was made in error; EPA did not intend to 
propose such a requirement. EPA did not propose to require a facility 
to document that an impoundment did not contain liquids prior to 
October 19, 2015. Nor did the 2015 CCR Rule require any facilities to 
document that they were not subject to regulation. These facilities 
were never subject to the exemption for inactive impoundments at 
inactive facilities that was vacated in the USWAG decision and 
therefore should not be regulated as part of EPA's action to implement 
the Court's order. Accordingly--and consistent with the 2015 CCR Rule--
if all CCR and liquids have been removed from the impoundment prior to 
October 19, 2015, nothing further is required.
    Under the definition in the final rule, a facility that initiated 
closure by removal prior to October 19, 2015, but whose impoundment 
still contained CCR and liquids on or after October 19, 2015 is 
considered a legacy CCR surface impoundment and regulated under this 
final rule, even if the facility has removed all CCR prior to the 
effective date of this final rule. Depending on when the impoundment 
completes closure, some individual requirements may no longer be 
applicable to the legacy CCR surface impoundment (e.g.,

[[Page 39000]]

when the compliance date in the final rule falls after the date closure 
is completed for the impoundment); but as EPA explained in the 
proposal, the Agency has no basis for concluding that all legacy CCR 
surface impoundments that are still in the process of closing pose no 
risk.
    The final rule retains the provision under which a facility with a 
CCR surface impoundment that contained CCR and liquids on October 19, 
2015, but that completed closure by removal before the effective date 
of this rule, would only be required to post documentation on the 
facility's CCR website that it has met the standards in Sec.  
257.102(c) for that unit (i.e., the certification of closure by removal 
for legacy CCR surface impoundments). To be eligible for the closure 
certification, the facility must document that it meets the criteria 
laid out in Unit III.B.2.b.iii. Namely, the facility must demonstrate 
that consistent with the existing standards, all CCR has been removed 
from the unit, any areas affected by releases from the CCR unit have 
been removed, and must have groundwater monitoring data demonstrating 
that the concentrations of each Appendix IV constituent do not exceed 
the relevant groundwater protection standard, which would be either the 
MCL or background concentration, for two consecutive sampling events.
    If a facility certifies all of the legacy CCR surface impoundments 
on-site have met the requirements in Sec.  257.102(c) for closure by 
removal before the effective date of this rule, the facility would not 
be subject to any further requirements under this final rule (i.e., 
neither legacy CCR surface impoundment requirements or CCRMU 
requirements).
    For similar reasons as explained above, EPA cannot accept the 
commenter's suggestion that EPA establish the same provision for 
facilities that closed a legacy impoundment prior to the effective date 
of this final rule in accordance with Sec.  257.102(d) (closure when 
leaving CCR in place) and allow facilities to simply demonstrate that 
the closure meets the performance standards in Sec.  257.102(d). The 
commenters appear to be requesting an exemption from post closure 
groundwater monitoring and corrective action requirements, but provided 
no factual basis for such an exemption. Nevertheless, as discussed in 
Unit III.B.2.g.iii of this preamble, if a facility can document that 
the closure of its unit meets the performance standards in Sec.  
257.102(d), all that would be required is compliance with the 
groundwater monitoring requirements in Sec. Sec.  257.90-257.95, and 
any necessary corrective action throughout the post-closure care period 
(in addition to recordkeeping and posting).
    The documentation requirements, procedures, and compliance 
deadlines for these various options are discussed further in Unit 
III.B.2.g of this preamble.
    EPA also disagrees with the commenter that 75,000 tons is a de 
minimis amount of CCR. The commenter has misunderstood EPA's findings 
in 2015; EPA did not conclude that quantities of CCR lower than 75,000 
tons used as fill does not pose any risk to human health or the 
environment. Rather EPA concluded that, while the agency has sufficient 
information to document that unencapsulated uses can present a hazard, 
based on the rulemaking record EPA lacked the information necessary to 
demonstrate that unencapsulated uses in amounts lower than 12,400 tons 
are likely to present a risk. 80 FR 21352. In any event, as discussed 
in Unit III.A.4, recent EPA modeling demonstrates that far lower 
quantities of CCR (1,000 tons) can pose significant risks to human 
health and the environment.
    In the 2015 CCR Rule, EPA provided guidance on which impoundments 
would not meet the definition of a CCR impoundment because they 
generally do not contain significant levels of CCR. 80 FR 21357. 
Specifically, EPA explained that CCR surface impoundments do not 
include units generally referred to as cooling water ponds, process 
water ponds, wastewater treatment ponds, storm water holding ponds, or 
aeration ponds. These units do not meet the definition of a CCR surface 
impoundment, that is, they are not designed to hold an accumulation of 
CCR and treatment storage or disposal of accumulated CCR does not occur 
in these units. Accordingly, EPA considers that such units would also 
not be legacy impoundments. EPA acknowledges that it mistakenly 
referred to one of these units as a CCR surface impoundment in the 
proposal, but that was an error.
c. Legacy CCR Surface Impoundment--Requirement To Be Located at an 
``Inactive Facility''
    EPA proposed to define an ``inactive facility'' (or inactive 
electric utility or independent power producer) as one that ceased 
producing electricity prior to October 19, 2015, which is the effective 
date of the 2015 CCR Rule. EPA explained that this date is also the 
same date currently used in the regulation to define ``active 
facility'' under Sec.  257.53, and that EPA originally used this date 
to define the exempted inactive units in the 2015 CCR Rule. The 
proposal further explained that use of this date would mean that the 
same universe of units that were subject to the original exemption 
would be regulated and that this is consistent with the Court's 
vacatur, as vacatur is intended to restore the status quo ante, as 
though the vacated provision never existed. 88 FR 31994, 32034.
    Commenters supported October 19, 2015, as the operative date to be 
used in the definition of an inactive facility because any other date 
would be inconsistent with the existing definition of an ``active 
facility.'' However, many commenters opposed the proposed substitution 
of the phrase ``regardless of the fuel currently used to produce 
electricity'' with ``regardless of how electricity is currently being 
produced at the facility.'' According to these commenters, the existing 
definition of ``active facility'' does not extend to facilities that do 
not use fuel, including, for example, facilities that produce solar 
power, because the plain language of Sec.  257.50(c) makes clear that, 
to be active, a facility must use a fuel to produce electricity. These 
commenters cite two preamble statements in the 2015 CCR Rule to support 
their allegation. The first is the applicability section of 2015 CCR 
Rule, which only references the NAICS 221112 (Fossil Fuel Power 
Generation). These commenters speculate that if EPA had intended for 
the term ``active facility'' to extend to facilities that do not use 
fuel to produce electricity, EPA would have included other NAICS codes. 
The second statement appears in the executive summary and explains that 
the rule applies to:

Certain inactive CCR surface impoundments (i.e., units not receiving 
CCR after the effective date of the rule) at active electric 
utilities or independent power producers' facilities, regardless of 
the fuel currently used at the facility to produce electricity 
(e.g., coal, natural gas, oil), if the CCR unit still contains CCR 
and liquids.

80 FR 21303.

    The commenters contended that EPA's proposal represents a 
significant change that will subject renewable generation to the CCR 
regulations (e.g., a former coal-fired power plant that was retired, 
closed and dismantled well in advance of the 2015 CCR Rule that had new 
renewable generation built at the facility), creating strong 
disincentives to renewable repowering at those sites. These commenters 
further added that such a change in position requires EPA to take 
reliance interests into account. To address this, the commenters made 
two suggestions. The first was that EPA should establish an exemption 
from regulation for inactive facilities that

[[Page 39001]]

generate 50 megawatt (MW) or less to the grid (all from renewable 
energy). The 50 MW threshold is consistent with the small generating 
units subcategory under the Federal effluent limitations guidelines and 
standards (ELG) regulations.\56\ In addition, the commenters believed 
that this would also account for sites that have utilized renewable 
energy (e.g., solar panels) for the primary purpose of powering the 
remaining infrastructure, but may potentially supply very limited 
amounts to the grid on occasion.
---------------------------------------------------------------------------

    \56\ 80 FR 67838 (November 3, 2015).
---------------------------------------------------------------------------

    The second suggestion was that EPA confirm that this is a 
prospective change and provide a pathway for compliance for facilities 
that would be newly subject to the CCR Rule. According to those 
facilities relied in good faith on the explanatory statements in the 
2015 CCR Rule preamble and the plain meaning of the term ``fuel,'' 
believed they were inactive facilities and did not have units subject 
to requirements of the CCR Rule, and accordingly should be allotted a 
separate new compliance timeframe.
    EPA disagrees that the phrase ``regardless of the fuel currently 
used to produce electricity'' under Sec.  257.50(c) indicates that EPA 
meant to limit the rule to facilities that combust fossil fuels. As EPA 
stated in the proposed rule, the definition of an active facility at 
Sec.  257.53 does not include any limitation related to how the 
facility generates electricity. The clause, ``regardless of the fuel 
currently used to produce electricity'' in Sec.  257.50(c) does not 
limit coverage only to facilities that use fuel to generate 
electricity. The plain language of the clause actually states the 
opposite; that coverage applies without regard to the fuel used to 
produce electricity. Or in other words, without regard to the type of 
fuel used or indeed whether any fuel is used to produce electricity.
    EPA also disagrees that either of the cited preamble statements 
demonstrate a contrary intent. As the commenters themselves 
acknowledge, the discussion of affected entities expressly states that 
it ``may not be exhaustive; other types of entities not listed could 
also be affected.'' 80 FR 21302. In addition, EPA expressly stated that 
``[t]o determine whether your facility, company, business, 
organization, etc., is affected by this action, you should refer to the 
applicability criteria discussed in Unit VI.A of this document.'' Id. 
Similarly, the parenthetical description ``(e.g., coal, natural gas, 
oil)'' uses the abbreviation e.g., which indicates that it is not 
comprehensive.
    Consequently, EPA disagrees that facilities have any reliance 
interest in a less expansive definition. Generally, a reliance interest 
may be implicated if an agency issues a policy, a party takes an action 
based on that policy, and the agency subsequently changes its policy. 
DHS v. Regents of the Univ. of Cal., 140 S. Ct. 1891, 1913 (2020). 
Here, EPA never changed its position, and there can be no legitimate 
reliance on a non-existent past position.
    Even if the regulatory amendment reflected a changed in policy, EPA 
issued a proposal and solicited comment from affected entities on the 
substance of the policy that would be in place in the final action. The 
commenters had an opportunity to provide EPA with information detailing 
their reliance interests, although they failed to do more than allege 
that they had reliance interests in remaining exempt. EPA has explained 
why, notwithstanding those interests, the agency believes that this is 
the better policy. No more is required. DHS v. Regents of the Univ. of 
Cal., supra at 1913.
    Nevertheless, EPA is sensitive to not creating disincentives to 
renewable repowering at those sites. In addition, EPA acknowledges that 
although commenters' interpretation is not the best reading of the 
provision, it is a plausible one. Accordingly, EPA has adopted the 
commenters' suggestion that the Agency provide a pathway to compliance 
for facilities that believed they were inactive facilities and did not 
have units subject to the requirements of the 2015 CCR Rule. This final 
rule provides that facilities producing electricity through renewables 
(i.e., non-fuels) are subject to the same applicable compliance 
deadlines for these units. See Sec.  257.100(a)(1).
    EPA is rejecting the commenters' suggestion that EPA exempt 
inactive facilities that generate 50 megawatt (MW) or less to the grid. 
This is because an exemption for small generating units based on 
current operations, such as renewable generation with a capacity of 50 
MW or less, do not necessarily correlate to the current risks resulting 
from past coal-fired generation operations.
d. Innocent Owners
    EPA proposed not to establish an ``innocent owner'' provision in 
the CCR regulations, in part because EPA had no factual basis to 
establish one. 88 FR 31994-95. The Agency received comments both 
opposing and supporting such a provision. Most commenters opposed the 
inclusion of an innocent owner provision in the final rule. Some of 
these stated that there is no statutory basis for uniformly excluding 
existing owners and operators from any RCRA regulations applicable to 
legacy impoundments. According to these commenters, the concept of an 
``innocent owner'' does not apply to legacy impoundments because only 
the owner of the regulated unit can fulfill obligations involving 
affirmative regulatory controls.
    Other commenters stated that relevant parties may allocate 
liability among themselves through various agreements and arrangements. 
These commenters explained that liability should not be rigidly limited 
only to the current owner, that liability should honor existing 
agreements (e.g., purchase and sale agreement), and that it may be 
appropriate under some circumstances for shared responsibility between 
the current owner and the utility. Another commenter stated that each 
of the utilities and each transferee should remain responsible for rule 
compliance regardless of how responsibility is currently allocated.
    Other commenters supported adoption of an innocent owner provision 
in the regulations. These commenters claimed that EPA is responsible 
for creating a new class of innocent owner when it changed the 2015 CCR 
regulations. Consequently, these commenters urged EPA to develop an 
innocent landowner provision that would allow both the utilities and 
developers to come to a mutual agreement as to who has the 
environmental and financial responsibility of these newly regulated 
units. Finally, another commenter suggested EPA take time to evaluate 
the different types of innocent property owners and then consider 
adding an innocent owner provision to the regulations.
    EPA has not included an innocent owner provision in the final rule. 
EPA explained in the proposal that its analysis of inactive facilities 
found that most inactive facilities are owned by companies that are 
already regulated by the CCR regulations. The analysis presented in the 
proposed rule indicated that approximately 80% of potential legacy 
impoundments (i.e., 126 of the 156 identified potential units) are 
owned by companies the Agency knows as already having units subject to 
the CCR regulations. 88 FR 31994. As a consequence, EPA proposed it had 
no factual basis to establish an innocent owner provision. 88 FR 31995. 
EPA has updated the ownership analysis based on an updated list of 
potential legacy impoundments. The revised analysis continues to 
indicate that most inactive

[[Page 39002]]

facilities are owned by companies that are already regulated by the CCR 
regulations. The 194 potential legacy impoundments identified in the 
final rule are associated with 52 different unique corporate parents. 
Of the 194 impoundments, 142 units (or 73%), are owned by 28 companies 
the Agency knows own facilities currently subject to the CCR 
regulations. The remaining 52 impoundments are owned by 24 different 
companies, with each company generally having just one location/site 
with legacy CCR surface impoundments (with two exceptions, that each 
own two sites).
    EPA is also aware of a number of instances in which parties have 
allocated liability among themselves through various agreements and 
arrangements. EPA infers from this that an innocent landowner provision 
is not necessary to allow utilities and developers to come to a mutual 
agreement on how best to allocate environmental and financial 
responsibility. EPA has no interest in taking actions that could 
potentially inhibit or interfere with these private arrangements. For 
all these reasons EPA continues to believe that an innocent owner 
provision is not currently needed and has not included such a provision 
in the final rule.
2. Applicable Requirements for Legacy CCR Surface Impoundments and 
Compliance Deadlines
    This Unit of the preamble first provides a general overview of how 
EPA determined the applicable requirements and compliance deadlines for 
legacy CCR surface impoundments. Then, EPA discusses each of the 
existing requirements for CCR surface impoundments and explains: (1) 
Why EPA is (or is not) applying them to legacy CCR surface 
impoundments; and (2) The rationale for the compliance deadline EPA is 
finalizing for each requirement.
a. General Overview
i. Applicable Requirements for Legacy CCR Surface Impoundments
    EPA proposed to apply all of the existing requirements in 40 CFR 
part 257, subpart D that are currently applicable to inactive CCR 
surface impoundments to legacy CCR surface impoundments, except for the 
location restrictions at Sec. Sec.  257.60 through 257.64, and the 
liner design criteria at Sec.  257.71. EPA also proposed one revision 
to the existing groundwater monitoring requirements and three new 
requirements specific to legacy CCR surface impoundments: a reporting 
requirement; a new security requirement to restrict public access to 
these sites; and a closure certification. As explained in the proposed 
rule, EPA proposed to exclude the location restrictions and the liner 
design criteria requirements because EPA believed they would not be 
necessary if EPA took final action on the proposed requirement that all 
legacy CCR surface impoundments initiate closure no later than 12 
months after the effective date of the final rule. Furthermore, the 
proposed rule explained that the record for the 2015 CCR Rule 
demonstrated that ``there is little difference between the potential 
risks of an active and inactive surface impoundment; both can leak into 
groundwater, and both are subject to structural failures that release 
the wastes into the environment, including catastrophic failures 
leading to massive releases that threaten both human health and the 
environment.'' 80 FR 21343. As discussed in Unit II.B of this preamble, 
the D.C. Circuit came to the same conclusion, and on that basis, 
vacated the exemption for legacy CCR surface impoundments. See, USWAG 
at 901 F.3d at 434. Based on the record, EPA considered that it has 
limited discretion to establish requirements for legacy CCR surface 
impoundments that are significantly different than those currently 
applicable to inactive CCR impoundments. This is also consistent with 
how the USWAG court viewed the 2015 record. Accordingly, EPA proposed 
that in most cases the existing requirements in 40 CFR part 257, 
subpart D applicable to inactive CCR surface impoundments would apply 
to legacy CCR surface impoundments.
    EPA received numerous comments on the proposed rule regarding the 
requirements applicable to legacy CCR surface impoundments. Several 
commenters generally supported the regulatory approach, although some 
suggested that legacy CCR surface impoundments be subject to all the 
existing CCR regulations, including the location restrictions at 
Sec. Sec.  257.60 through 257.64 and the liner design criteria at Sec.  
257.71. Other commenters stated that the inspections at Sec.  257.83 
were only relevant for operating CCR units and therefore should not be 
applied to legacy CCR surface impoundments. A few commenters suggested 
EPA create additional requirements for legacy CCR surface impoundments 
such as zero discharge limits, new reporting requirements, financial 
assurance measures, and beneficial reuse restrictions. Other commenters 
suggested that EPA revise the existing requirements applicable to 
inactive impoundments, including by adding requirements to the fugitive 
dust, closure, and post-closure care requirements; further revising the 
groundwater monitoring requirements to ban intrawell data comparisons; 
mandating closure by removal; and using a risk-based approach for 
corrective action and closure requirements.
    EPA still considers that based on the record (as described in III.A 
of this preamble), EPA has limited discretion to establish requirements 
for legacy CCR surface impoundments that are significantly different 
than those currently applicable to inactive CCR impoundments. For that 
reason and those laid out in the preamble of the proposed rule, EPA did 
not adopt any of the new requirements, such as zero discharge limits, 
new reporting requirements, financial assurance measures, or new 
beneficial use restrictions suggested by commenters. The final rule 
contains only one additional revision of the existing requirements for 
inactive CCR surface impoundments beyond the four included in the 
proposed rule: the deferral to permitting of certain closure 
activities. The rationale for the final requirements is detailed in 
subsequent sections in this Unit.
    For the reasons detailed in the proposed rule, except for certain 
legacy impoundments, EPA is finalizing the requirement for legacy CCR 
surface impoundments to comply with the existing regulations in 40 CFR 
part 257, subpart D applicable to inactive CCR surface impoundments 
except for the location restrictions at Sec. Sec.  257.60 through 
257.64, and the liner design criteria at Sec.  257.71. EPA is also 
finalizing the revision to the existing groundwater monitoring 
requirements, combining detection and assessment monitoring for legacy 
CCR surface impoundments and the two new requirements specific to 
legacy CCR surface impoundments: the applicability documentation (Sec.  
257.100(f)(1)(i)) and the site security requirement (Sec.  
257.100(f)(3)(iii)).
    The final rule also establishes a tailored subset of requirements 
applicable to legacy CCR surface impoundments that were closed prior to 
the effective date of this rule, including those impoundments whose 
closures qualify for deferral because they were conducted in accordance 
with substantially equivalent State or Federal requirements. See Unit 
III.B.2.g.iii.(b) of this preamble for further discussion of the 
deferral.

[[Page 39003]]

(a) Applicable Requirements for Legacy CCR Surface Impoundments Closed 
by Removal
    EPA is finalizing a tailored subset requirements for legacy CCR 
surface impoundments that have completed closure by removal before the 
effective date of this final rule but are not able to complete the 
certification of closure by removal (see, Unit III.B.2.b.iii). For the 
reasons detailed in this Unit and in the following Units of the 
preamble (Units III.B.2.b-III.B.2.h), the owner or operator of such 
units must comply with the following requirements: the applicability 
report, installation of a permanent marker, all groundwater monitoring 
and corrective action (including combined detection monitoring and 
assessment monitoring), recordkeeping, notification, and website 
posting. In addition, if a CCRMU is discovered onsite during the course 
of complying with the Facility Evaluation Report (FER), the owner or 
operator of these units must develop a fugitive dust control plan (see 
Unit III.C.3).
    While EPA acknowledges that these closed units are unlikely to have 
any ongoing activities that would create fugitive dust, EPA determined 
that requiring these units to comply with the fugitive dust requirement 
was appropriate because these units are subject to the CCRMU 
requirements and there is a reasonable likelihood that CCR fugitive 
dust would be generated as part of the actions required to comply with 
those requirements (e.g., field work to determine the presence or 
absence of CCRMU, CCRMU closure). As such, if a CCRMU is discovered 
onsite of a facility with a legacy CCR surface impoundment that has 
closed by removal, the owner or operator must complete a fugitive dust 
plan no later than six months after the FER is due (i.e., no later than 
33 months after becoming subject to these requirements).
    EPA determined that the site security requirements applicable to 
other legacy CCR surface impoundments would not be relevant for this 
subset of units as the CCR has been removed from the unit and the land 
may be being used for another purpose (e.g., nature preserve, 
agricultural land, redevelopment). However, EPA expects legacy CCR 
surface impoundments that closed by removal to protect the monitoring 
equipment and monitoring wells, similar to other legacy CCR surface 
impoundments.
    EPA is also not requiring these units to comply with any other 
design criteria or operating criteria, aside from the installation of 
the permanent marker and the fugitive dust requirements, as noted 
above. EPA has determined that the other design and operating criteria 
are not applicable to units that have closed by removal and therefore 
no longer contain CCR in the unit on the effective date of this final 
rule. For example, the requirement to prepare and maintain an EAP is 
not relevant when CCR is no longer present in the unit nor is the 
requirement to conduct weekly inspections of the legacy impoundment.
(b) Applicable Requirements for Legacy CCR Surface Impoundments That 
Closed With Waste in Place
    EPA is finalizing a tailored subset of requirements for legacy CCR 
surface impoundments that, by the effective date of this final rule, 
have completed: (1) closure with waste in place or (2) a closure 
eligible for deferral to permitting as described in Unit 
III.2.g.iii(b). For the reasons detailed in this Unit and in the 
following sections (Units III.B.2.b-III.B.2.h), the owner or operator 
of such units must comply with the following requirements: 
applicability report, site security, installation of the permanent 
marker, history of construction, fugitive dust control plan, annual 
fugitive dust control report, all groundwater monitoring and corrective 
action (including combined detection monitoring and assessment 
monitoring), written post-closure care plan, post-closure care, 
recordkeeping, notification, and website posting. In addition, the 
final rule requires the facility to provide information on the 
completed closure of the legacy CCR surface impoundment, along with 
supporting documentation to demonstrate that the closure meets the 
performance standards in Sec.  257.102(d) or the standards specified in 
Sec.  257.101(g).
    While EPA acknowledges that these closed units are unlikely to have 
any ongoing activity that would create fugitive dust, EPA determined 
that requiring these units to comply with the fugitive dust requirement 
was appropriate because these units are subject to the CCRMU 
requirements and there is a reasonable likelihood that CCR fugitive 
dust would be generated as part of the actions required to comply with 
those requirements (e.g., field work to determine the presence or 
absence of CCRMU, CCRMU closure). As such, if a CCRMU is discovered 
onsite of a facility with a legacy CCR surface impoundment that has 
closed by removal, the owner or operator must complete a fugitive dust 
plan no later than six months after the FER is due (i.e., no later than 
33 months after becoming subject to these requirements).
    EPA is also finalizing the requirement for this subset of legacy 
CCR surface impoundments to comply with the site security requirements 
applicable to other legacy CCR surface impoundments. EPA determined 
that the site security requirements are needed to minimize the 
potential for the unauthorized entry of people or animals to disturb 
the final cover system, as these units are unlikely to be monitored. 
EPA also expects facilities that closed legacy CCR surface impoundments 
with waste in place to protect the monitoring equipment and monitoring 
wells, similar to other legacy CCR surface impoundments.
    This final rule also requires the owners and operators of these 
units to complete the history of construction in accordance with Sec.  
257.73(c). The history of construction provides information regarding 
the original site conditions, as well as the unit's original design and 
construction, such as cross sections of the length and width of the CCR 
unit. It would also include information on subsequent revisions, such 
as the design and construction of any lateral expansions. This 
information is relevant to designing (and evaluating) the groundwater 
monitoring system, unit closures, and corrective actions. For example, 
the history of construction would normally include the elevations of 
the unit base and the CCR in the unit (i.e., the ground elevation 
contours within the footprint prior to unit construction); this 
information, in conjunction with the site characterization developed 
under Sec.  257.90 to design the groundwater monitoring system can be 
used to determine whether the unit intersects with the groundwater 
(i.e., the unit's ability to sufficiently contain CCR and contaminants 
that may leach from CCR). This information remains relevant in 
evaluating closure, when addressing any contamination coming from the 
unit, and throughout the post-closure care period. Therefore, EPA is 
requiring this subset of legacy CCR surface impoundments to comply with 
the history of construction requirement.
    EPA has determined that the other design and operating criteria 
(all those besides the permanent marker, site security, history of 
construction, and fugitive dust requirements) are not applicable to 
units that have completed closure in accordance with Sec.  257.102(d) 
by the effective date of this final rule. For example, the requirement 
to prepare an inflow design flood control system plan is not relevant 
for units that have installed a final cover system, as post-

[[Page 39004]]

closure care requires a final cover system to be maintained and 
groundwater monitoring to continue. Additionally, periodic assessments, 
such as the hazard potential classification assessment and the 
structural stability assessments, are intended to address risks from 
unclosed unit and therefore, consistent with the requirements for units 
that have completed closure under the 2015 CCR Rule, are not applicable 
to units that have closed with waste in place.
ii. Compliance Deadlines for Legacy CCR Surface Impoundments
    EPA proposed to establish new compliance dates for legacy CCR 
surface impoundments. The proposed rule explained that the 2015 CCR 
Rule compliance deadlines were based on the amount of time determined 
to be necessary to implement the requirements and the proposed 
compliance dates for legacy CCR surface impoundments were determined 
using the same approach. The proposed rule further explained that some 
factors considered in determining the 2015 CCR Rule compliance 
deadlines were not relevant for legacy CCR surface impoundments, such 
as the need coordinate compliance deadlines with the then recently 
promulgated ELG rule. In addition, EPA anticipated most facilities 
would already be familiar with the existing regulations, and therefore 
the proposed requirements for legacy CCR surface impoundments, and 
fewer facilities and units would need to come into compliance, as 
compared to the 2015 CCR Rule. Consequently, EPA proposed generally 
expedited deadlines based on the expected shortest average amount of 
time needed to complete the necessary activities to meet the 
requirements. In the proposed rule, EPA requested comment on the 
proposed compliance deadlines and the feasibility to meet the proposed 
compliance timeframes for legacy CCR surface impoundments.
    EPA received numerous comments regarding the proposed compliance 
deadlines. Several commenters expressed support for the proposed 
compliance deadlines for legacy CCR surface impoundments. Generally, 
these commenters stated that expedited compliance was appropriate due 
to the increased risk posed by these units, the likelihood that these 
units are actively contaminating groundwater, and the urgent need for 
corrective action to address that contamination for the protection of 
human health and the environment. Some of these commenters echoed the 
proposed rule, stating that owner's or operator's familiarity with the 
existing requirements, along with the fact that these units are no 
longer in use and therefore would not need time to cease receipt of 
waste, further justified the expedited deadlines.
    Many other commenters stated the proposed compliance deadlines were 
infeasible and should, at a minimum, allow as much time for compliance 
as the 2015 CCR Rule deadlines, although several commenters expressed 
that even the 2015 CCR Rule deadlines were inadequate, and that the 
insufficient timeframes were likely a factor in the gap between EPA's 
expectations and facilities' good faith efforts and utilization of best 
practices in developing groundwater monitoring networks, sampling and 
analysis plans, corrective action programs, and closure plans. 
Commenters pointed to several factors that they believed EPA did not 
fully incorporate into the proposed deadline calculations that make 
compliance with the proposed deadlines infeasible: the large number of 
CCR units (i.e., existing CCR units, legacy CCR surface impoundments, 
CCRMU) competing for limited resources to meet overlapping compliance 
deadlines; the limited number of qualified contractors available to 
conduct necessary activities to reach the compliance deadlines; the 
nationwide labor shortage exacerbated by impacts from the COVID-19 
pandemic; limited existing alternative disposal options; overlapping 
regulatory requirements (e.g., State drilling permits, timing 
restrictions related to protected habitats, State CCR permits, Consent 
Decrees/Orders); seasonality impacts in different regions across the 
nation; and accessibility and completeness, or lack thereof, of 
historical documentation and information. One commenter provided 
specific information regarding typical delays experienced during the 
implementation of the 2015 CCR Rule caused by third-party availability 
and backlogs: two to four weeks for contractor mobilization; two to six 
weeks for site clearing; two to three weeks for surveys; three to 12 
weeks for environmental drillers; and three to four weeks for 
laboratory analyses. These commenters also said EPA grossly 
underestimated the amount of time needed to hire a contractor, locate 
and review historical information, access a legacy CCR surface 
impoundment site, characterize and delineate a site, comply with the 
groundwater monitoring requirements, and conduct quality control or 
quality assurance on data and reports. Several of these commenters 
expressed the belief that the proposed deadlines would result in 
unintentional non-compliance despite facilities' best efforts to comply 
due to the constraints listed above. Finally, a few commenters 
suggested EPA create alternative deadlines or mechanisms for extensions 
based on site-specific characteristics.
    In response to comments, EPA reevaluated the compliance deadlines 
for legacy CCR surface impoundments. EPA reconsidered the impact of the 
following on the amount of time facilities needed to complete the 
activities involved in meeting the requirements: accessibility and 
abundance, or lack thereof, of historical documentation; seasonality; 
clearing restrictions and required local and State approvals to clear 
vegetation or drill wells; existing disposal options; impact of the 
national labor shortage and contractor and laboratory backlogs; and 
overlapping compliance deadlines for CCRMU, existing units (i.e., 
groundwater monitoring, closure, and post-closure care), and legacy CCR 
surface impoundments. Overall, EPA found the information provided 
regarding the infeasibility of the proposed deadlines convincing. 
Specifically, EPA agrees that the shortage of qualified contractors and 
laboratory resources has persisted, if not increased, since the 2015 
CCR Rule and that the increasing demand on these finite resources from 
new and existing CCR units, legacy CCR surface impoundments, and CCRMU 
complying with overlapping requirement deadlines will likely increase 
the time needed to come into compliance. EPA acknowledges that the 
proposed deadlines did not adequately account for those nationwide 
impacts of seasonality and extreme weather events; necessary 
coordination with outside parties (e.g., State agencies, local 
governments); locating disposal capacity for those units closing by 
removal; the need to comply with overlapping regulatory requirements, 
such as State drilling permits or timing restrictions related to 
protected habitats; or necessary quality assurance and quality control 
in calculating the proposed deadlines. Therefore, as detailed in Units 
III.B.2.b through h, EPA extended the deadlines for legacy CCR surface 
impoundments to provide at least as much time facilities had to come 
into compliance with the 2015 CCR Rule. In some cases, EPA extended the 
deadlines for legacy CCR surface impoundments even further to mitigate 
factors mentioned by commenters that convinced EPA the 2015 compliance

[[Page 39005]]

deadlines would be infeasible for legacy impoundments. Overall, most of 
the comments EPA received supported deadlines that allowed at least as 
much time as EPA originally provided in the 2015 CCR Rule. While some 
units regulated by the 2015 CCR Rule were able to come into compliance 
before the 2015 deadlines, the majority of units used all the time 
allowed by the 2015 CCR Rule.
    Note that all deadlines herein are framed by reference to the 
effective date of the rule; the final rule will be effective six months 
after publication of the final rule. Accordingly, facilities will have 
an additional six months beyond the deadlines to come into compliance. 
The Agency has included a document in the docket for this rule that 
summarizes the finalized compliance deadlines.\57\
---------------------------------------------------------------------------

    \57\ A document ``Final Rule Compliance Deadlines for Legacy CCR 
Surface Impoundments. April 2024.'' is available in the docket for 
this action.

                    Table 1--Final Compliance Time Frames for Legacy CCR Surface Impoundments
----------------------------------------------------------------------------------------------------------------
                                            Description of      Deadline  (months after
      40 CFR Part 257, Subpart D          requirement to be      effective date of this            Date
             requirement                      completed               final rule)
----------------------------------------------------------------------------------------------------------------
Applicability Report (Sec.   257.100)  Complete applicability   0......................  Friday, November 8,
                                        report.                                           2024.
Internet Posting (Sec.   257.107)....  Establish CCR website..  0......................  Friday, November 8,
                                                                                          2024.
Site Security (Sec.                    Implement site security  0......................  Friday, November 8,
 257.100(f)(3)(iii)).                   measures.                                         2024.
Operating Criteria (Sec.   257.80)...  Prepare fugitive dust    0......................  Friday, November 8,
                                        control plan.                                     2024.
Operating Criteria (Sec.   257.80,     Initiate weekly          0......................  Friday, November 8,
 257.82, 257.83).                       inspections of the CCR                            2024.
                                        unit.
Operating Criteria (Sec.   257.80,     Initiate monthly         0......................  Friday, November 8,
 257.82, 257.83).                       monitoring of CCR unit                            2024.
                                        instrumentation.
Design Criteria (Sec.   257.73)......  Install permanent        2......................  Wednesday, January 8,
                                        marker.                                           2025.
Operating Criteria (Sec.   257.80,     Complete initial annual  3......................  Monday, February, 10,
 257.82, 257.83).                       inspection of the CCR                             2025.
                                        unit.
Operating Criteria (Sec.   257.80)...  Complete initial annual  14.....................  Thursday, January 8,
                                        fugitive dust report.                             2026.
Design Criteria (Sec.   257.73)......  Compile history of       15.....................  Monday, February 9,
                                        construction.                                     2026.
Design Criteria (Sec.   257.73)......  Complete initial hazard  18.....................  Friday, May 8, 2026.
                                        potential
                                        classification
                                        assessment.
Design Criteria (Sec.   257.73)......  Complete initial         18.....................  Friday, May 8, 2026.
                                        structural stability
                                        assessment.
Design Criteria (Sec.   257.73)......  Complete initial safety  18.....................  Friday, May 8, 2026.
                                        factor assessment.
Design Criteria (Sec.   257.73)......  Prepare emergency        18.....................  Friday, May 8, 2026.
                                        action plan.
Operating Criteria (Sec.   257.82)...  Complete initial inflow  18.....................  Friday, May 8, 2026.
                                        design flood control
                                        system plan.
GWMCA (Sec.  Sec.   257.90-257.95)...  Install the groundwater  30.....................  Monday, May 10, 2027.
                                        monitoring system,
                                        develop the
                                        groundwater sampling
                                        and analysis program,
                                        initiate the detection
                                        monitoring and
                                        assessment monitoring.
                                        Begin evaluating the
                                        groundwater monitoring
                                        data for SSIs over
                                        background levels and
                                        SSLs over GWPS.
GWMCA (Sec.   257.90(e)).............  Complete initial annual  January 31, 2027.......  January 31, 2027.
                                        GWMCA report.
Closure (Sec.  Sec.   257.100-         Prepare written closure  36.....................  Monday, November 8,
 257.101).                              plan.                                             2027.
Post-Closure Care (Sec.   257.104)...  Prepare written post-    36.....................  Monday, November 8,
                                        closure care plan.                                2027.
Closure and Post-Closure Care (Sec.    Initiate closure.......  42.....................  Monday, May 8, 2028.
 257.101).
----------------------------------------------------------------------------------------------------------------

b. New Requirements Specific to Legacy CCR Surface Impoundments
i. Applicability Report for Legacy CCR Surface Impoundments
    EPA proposed to require the owner or operator of a legacy CCR 
surface impoundment to prepare an applicability report for any legacy 
CCR surface impoundment at that facility no later than the effective 
date of the final rule. This requirement would apply to all legacy CCR 
surface impoundments, including incised impoundments and impoundments 
that do not meet the height and storage volume cutoffs specified in 
Sec.  257.73(b). EPA proposed that this applicability report would 
include information to identify the unit, delineate the unit 
boundaries, include a figure of the facility and where the unit is 
located at the facility, the size of the unit, its proximity to surface 
water bodies, and the current site conditions. EPA also proposed that 
the applicability report include the facility address, latitude and 
longitude, and contact information of the owner and/or operator of the 
legacy CCR surface impoundment with their business phone number and 
email address. EPA proposed that the report should document whether the 
legacy CCR surface impoundments are incised and whether the units meet 
the height and storage volume thresholds specified in Sec.  257.73(b). 
EPA also proposed that the owner or operator of the legacy CCR surface 
impoundment notify the Agency

[[Page 39006]]

after a legacy impoundment is identified and the facility's CCR website 
is established, using the procedures currently in Sec.  257.107(a) via 
the ``contact us'' form on EPA's CCR website. 88 FR 31998.
    EPA received a few comments on the applicability report. Several 
commenters said the deadline to complete requirements of the 
applicability report could not be achieved. One commenter requested 24 
months to complete the report. Another commenter presented several 
clarifying questions and said they could not estimate a compliance 
deadline without understanding these clarifications. This commenter 
asked if EPA will allow affected utilities to rely on information 
previously submitted to State regulatory authorities to satisfy the 
facility description requirements; what does EPA mean by the term 
``current site conditions'' in the context of facility site 
descriptions; when EPA refers to providing a site identification number 
as previously provided to the State, is this intended only to apply in 
States that have achieved CCR Rule delegation, or in all States in 
which there is some level of State oversight over a legacy CCR surface 
impoundment; and if EPA can further determine what it considers to be 
``reasonably and readily available information'' concerning history of 
construction. The commenter appreciates EPA's recognition that most of 
this information is likely ``unknown or lost to time,'' but seeks 
additional guidance on the scope of investigation that should be 
conducted to meet the ``reasonably and readily available'' standard.
    EPA believes that as part of the applicability report, an owner or 
operator of an inactive CCR facility can include information previously 
submitted to State regulatory authorities to describe the facility 
conditions. If, however, any changes have been made since the owner or 
operator last prepared that information or that information does not 
address all the issues inherent in an applicability determination, then 
updated or additional information should be included. The current site 
conditions should include, for example, when the facility operated, 
when it ceased generating electricity, the size of the facility 
property, a visual description of how the legacy impoundment looks on 
the effective date of the final rule (e.g., ponded water, approximate 
size, vegetation, incised), a description of any nearby geological or 
hydrologic features (i.e., rivers, lakes, streams, karst topography), 
and any other relevant information about the facility. The State 
identification number can be for a previously issued solid waste, 
water, or other permit under State program, but does not have to be as 
part of an EPA-approved State CCR permit program.
    EPA addressed the term ``reasonably and readily available'' at 80 
FR 21380, ``[t]herefore, in this rule, EPA is using the phrase `to the 
extent available' and clarifying that the term requires the owner or 
operator to provide information on the history of construction only to 
the extent that such information is reasonably and readily available. 
EPA intends facilities to provide relevant design and construction 
information only if factual documentation exists. EPA does not expect 
owners or operators to generate new information or provide anecdotal or 
speculative information regarding the CCR surface impoundment's design 
and construction history.''
    Based on the comments about the infeasibility to complete the 
proposed requirements by the effective date of the final rule, EPA is 
not requiring that the applicability report include the size of the 
unit, its proximity to surface water bodies, or delineation of the unit 
boundaries. The size of the unit and delineation of the unit boundaries 
will be determined through the history of construction and groundwater 
monitoring requirements. Proximity to surface water bodies is not 
required by the 2015 CCR Rule, and EPA determined it is not feasible to 
determine the distance to surface water bodies before the unit 
boundaries are delineated, which would not be done by the effective 
date of the final rule. Therefore, EPA is not requiring proximity to 
surface water bodies to be completed in the applicability report.
    Some commenters agreed with the proposed requirements on the 
applicability report and urged EPA to require additional information, 
including an EPA identification number, determination and public 
disclosure of whether legacy CCR surface impoundments contained both 
CCR and liquids, location and elevation of any 100-year floodplain 
within one mile, elevation and depth of CCR waste in the impoundment, 
proximity to public water supply wells or private water wells within 
two miles, proximity to wetlands, results of all environmental 
sampling, and owner/operator certification of the documentation. A 
commenter also said the applicability report should include a full 
investigation including the use of appropriate instrumentation to 
determine water levels, a report documenting the results certified by a 
qualified professional engineer, and the publication of the report on a 
CCR website.
    EPA considered these comments and decided not to require additional 
information since the recommended information would not be feasible to 
collect by the effective date of the final rule, especially given the 
limitations discussed in Unit III.B.2.a.i of this preamble. As stated 
previously, commenters discussed how delineating the unit boundaries 
and determining the exact location of the legacy CCR surface 
impoundment could not feasibly be completed by the deadline.
    EPA is finalizing with revisions the proposed requirement for the 
owner or operator of a legacy CCR surface impoundment to prepare 
applicability reports for all legacy CCR surface impoundments at that 
facility no later than the effective date of the final rule. This 
requirement applies to all legacy CCR surface impoundments, including 
incised impoundments and impoundments that do not meet the height and 
storage volume cutoffs specified in Sec.  257.73(b). This is codified 
in the regulatory text at Sec.  257.100(f)(1)(i). The applicability 
report must include information to identify the unit, a figure of the 
facility and where the unit is located at the facility, and the current 
site conditions. The applicability documentation must also include the 
facility address, latitude and longitude, and contact information of 
the owner and/or operator of the legacy CCR surface impoundment with 
their phone number and email address. EPA is also finalizing the 
requirement that the owner or operator of the legacy CCR surface 
impoundment notify the Agency of the establishment of the facility's 
CCR website using the procedures currently in Sec.  257.107(a) via the 
``contact us'' form on EPA's CCR website.
    Further, EPA is finalizing a requirement that a certification of 
the applicability report must be signed by the owner or operator or an 
authorized representative similar to the certification that is required 
at Sec.  257.102(e) and Sec.  257.102(f) for existing units undergoing 
closure. EPA proposed this requirement in Sec.  257.75(c) for the FER 
and determined after reviewing the comments that a similar requirement 
should apply to the applicability report. This requirement is codified 
in the regulatory text at Sec.  257.100(f)(1)(ii)(C).
    For any legacy impoundments that have completed closure by removal 
or closure in place of the unit pursuant to a State permit or order 
that meets the requirements of Sec.  257.101(g) prior to the effective 
date of this final rule, EPA is requiring the owner or operator to 
attach

[[Page 39007]]

such documentation to the applicability report required by Sec.  
257.100(f)(1) and post this documentation to its CCR website. This 
information will be evaluated by EPA permitting authorities at a future 
time to determine what further action, if any, is needed with the unit.
    As discussed in Unit III.B.1.b.i.(b)(4) of this preamble, EPA is 
establishing a new definition of the phrase ``contains both CCR and 
liquids'' in the final rule. Under this definition CCR and liquids are 
present in a CCR surface impoundment except where the owner or operator 
has demonstrated that free liquids have been eliminated from the unit 
consistent with the performance standard in Sec.  257.102(d)(2)(i). EPA 
recognizes that some owners and operators of inactive impoundments may 
not currently have records to demonstrate whether their inactive 
impoundment contained both CCR and liquids on or after October 19, 
2015. In such cases, one option would be for the facility to conduct a 
field investigation to assess whether free liquids are currently 
present in the unit. To facilitate such investigations, the final rule 
establishes procedures to provide owners or operators with additional 
time to complete the legacy impoundment applicability report, should 
the owner or operator elect to conduct a field inspection to assess the 
unit for the presence or absence of free liquids. See Sec.  
257.100(f)(1)(v). To be clear, facilities are not required to conduct 
field testing to determine whether their unit is a legacy CCR surface 
impoundment. If records are available to allow the owner or operator to 
make that determination, this final rule does not require them to 
conduct field testing to confirm that information. However, to the 
extent facilities would prefer to rely on field investigations to 
supplement, or lieu of, a purely record-based investigation this final 
rule provides that option.
    In order to obtain additional time to complete the legacy 
impoundment applicability report required under Sec.  257.100(f)(1), an 
owner or operator must prepare an ``applicability extension report'' by 
the effective date of the final rule. The extension report consists of 
three parts. First, the extension report must include general 
identifying information about the potential legacy impoundment, 
including, the name associated with the unit, the identification number 
of the unit if one has been assigned by the State, and information 
about the location of the unit at the facility. This information is 
same as the first three elements of the applicability report under 
Sec.  257.100(f)(1)(i)(A) through (C).
    Second, the extension report must include a statement by the owner 
or operator that available information does not provide a sufficient 
basis to determine that the inactive impoundment contained free liquids 
on or after October 19, 2015. Owners or operators that cannot make this 
statement are not eligible for this extension and must comply with the 
applicable requirements for legacy impoundments. For example, an owner 
or operator who knows that the unit currently contains liquids, or has 
aerial photographs from 2018 showing that the inactive impoundment 
contained standing or free water would not be eligible to make use of 
these extension provisions because the unit contained free liquids 
since October 19, 2015.
    Finally, the extension report must contain a written field 
investigation workplan. The purpose of this plan is to describe the 
approach the owner or operator intends to follow to determine whether 
the inactive impoundment contains free liquids. The written field 
investigation workplan must contain the following elements:
     A detailed description of the approach to characterize the 
physical, topographic, geologic, hydrogeologic, and hydraulic 
properties of the CCR in the unit and native geologic materials beneath 
and surrounding the unit, and how those properties will be used to 
investigate for the presence of free liquids in the CCR unit.
     A detailed description of the methods and tools that will 
be employed to determine whether the inactive impoundment contains free 
liquids, the rationale for choosing these methods and tools, and how 
these methods and tools will be implemented, and at what level of 
spatial resolution at the CCR unit to identify and monitor the presence 
of free liquids.
     A detailed description of how groundwater elevations will 
be determined, and at what level of spatial resolution, in relation to 
the sides and bottom of the CCR unit and how any interaction of the 
groundwater table with the CCR unit will be evaluated, and at what 
level of spatial resolution.
     A plan for evaluating stormwater flow over the surface of 
the unit, stormwater drainage from the unit, and stormwater 
infiltration into the unit and how those processes may result in the 
formation of free liquids in the CCR unit. This plan must include a 
current topographic map showing surface water flow and any pertinent 
natural or man-made features present relevant to stormwater drainage, 
infiltration and related processes.
     An estimated timeline to complete the workplan and make a 
determination if the CCR unit contains free liquids.
     A narrative discussion of how the results from 
implementing the workplan will determine whether the unit contains free 
liquids specified.
     A narrative discussion describing any anticipated problems 
that may be encountered during implementation of the workplan and what 
actions will be taken to resolve the problems, and anticipated 
timeframes necessary for such a contingency.
    The final rule allows an owner to operator to obtain as many as 
three 6-month extensions (or 18 months from the effective date of the 
final rule) to complete the field investigation. Each six-month time 
extension must be supported by an updated extension report to justify 
the need for additional time. If the owner or operator needs either of 
the additional 6-month extensions, the subsequent extension report must 
be prepared no later than six months after completing the preceding 
extension report. Each prepared extension report must be placed in the 
facility's operating record as required Sec.  257.105(k)(2) and posted 
to the owner or operator's CCR website.
    Once the owner or operator determines that an inactive impoundment 
contains CCR and liquids the applicability report required by Sec.  
257.100(f)(1) must be completed within 14 days of the determination. 
EPA believes 14 days is a sufficient amount of time to complete the 
applicability report because the information will be known to owners or 
operators at this point. Following preparation of the applicability 
report, the inactive impoundment is subject to the requirements for 
legacy impoundments under Sec.  257.100(f)(2) through (5), but with 
compliance deadlines adjusted by the length of the extension. These new 
timeframes are calculated on a unit-by-unit basis because the date the 
applicability report was prepared can vary by unit.
    This following example illustrates how the new compliance 
timeframes are calculated for one of the design criteria for legacy 
impoundments. Section 257.100(f)(2)(i) requires that the permanent 
identification marker must be placed on or immediately adjacent to the 
legacy impoundment no later than 2 months after the effective date of 
the rule. If the owner or operator determines 10.5 months after the 
effective date of the rule that free liquids are present in the 
inactive impoundment, the owner or operator must prepare the legacy

[[Page 39008]]

impoundment applicability report with 14 days of that date. The new 
deadline for the owner or operator to install the permanent marker is 
11 months after the original deadline (or in this case, 13 months from 
the effective date of the final rule (2+ 10.5 + 0.5 months)).
    Finally, if the owner or operator determines that the unit does not 
contain liquids, the owner or operator must prepare a notification 
stating that the field investigation has concluded and that the owner 
or operator has determined that the inactive impoundment does not 
contain CCR and liquids. This notification informs the public, States 
and EPA that the unit is not a legacy CCR surface impoundment. The 
final rule also provides that if the owner or operator does not 
complete the field investigation work within the timeframes specified 
in Sec.  257.100(f)(1)(iv)(B), the inactive impoundment shall be 
considered a legacy CCR surface impoundment and must comply with all 
applicable requirements under the new timeframes specified under Sec.  
257.100(f)(1)(iv)(E).
ii. Site Security for Legacy CCR Surface Impoundments
    Active facilities generally have guards and fencing to control 
access to the facility, but inactive CCR facilities may not have such 
security controls in place at the facility. To minimize that risk, EPA 
proposed that owners or operators establish security controls to 
restrict access to legacy CCR surface impoundments. The proposed 
security requirements are written in terms of a performance standard, 
as opposed to a prescriptive set of technical standards, such as 
specific signage, barriers and fencing, or surveillance techniques. EPA 
chose this approach because it would allow the owner or operator to 
identify the most appropriate means of providing site security for the 
impoundment based on site-specific circumstances.
    Commenters generally supported performance-based site security 
measures rather than having EPA prescribe specific technical standards. 
Some commenters agreed that such requirements are necessary because 
legacy CCR impoundments are located at inactive power plants, and 
unlike impoundments at operating power plants, they almost certainly 
lack the oversight and protection afforded by significant numbers of 
on-site personnel. These commenters stated that the integrity of 
impoundments and berms and the safety of nearby residents depend on 
robust security measures to ensure that people are not--whether 
intentionally or unknowingly--entering the site and taking actions 
(such as all-terrain vehicle driving, dirt biking, or similar 
activities) that endanger the integrity of the impoundment or expose 
trespassers to health risks. Some commenters added that EPA should 
consider that some sites may not need security measures, for example, 
sites with closed legacy impoundments that closed under State programs, 
especially where CCR have been removed. EPA did not receive comments 
about the deadline to complete the site security requirements and is 
therefore finalizing as proposed.
    EPA is adopting the proposed site security performance standard 
without revision from the proposal. Accordingly, the site security 
performance standard in the final rule requires the owner or operator 
to prevent the unknowing entry of people onto the legacy CCR surface 
impoundment and to minimize the potential for the unauthorized entry of 
people or livestock onto the impoundment. This is codified in the 
regulatory text in Sec.  257.100(f)(3)(ii). The Agency generally 
modeled the requirements on the existing regulations that apply to 
interim status hazardous waste surface impoundments, which are codified 
at Sec.  265.14(a). EPA recognizes that some facilities may already 
have facility-wide access controls in place, and in this case, the 
facility-wide controls would satisfy the requirement to limit public 
access to the legacy CCR surface impoundment. The Agency is finalizing 
the requirement for the facility to restrict access to the area 
containing the legacy CCR surface impoundment no later than the 
effective date of the final rule.
iii. Certification of Closure by Removal for Legacy CCR Surface 
Impoundments
    EPA proposed that legacy CCR surface impoundments that completed 
closure by removal of CCR in accordance with the performance standards 
in Sec.  257.102(c) after October 19, 2015, but before the effective 
date of the final rule would be subject to no further requirements 
under 40 CFR part 257, subpart D, provided the owner or operator 
completed certain actions.\58\ 88 FR 31998 and proposed Sec.  
257.100(f)(1)(ii). Specifically, EPA proposed that the owner or 
operator would be required to post documentation on their CCR website 
showing that the legacy impoundment was closed in accordance with the 
closure by removal standards in Sec.  257.102(c). EPA further proposed 
to require that the closure certification be certified by a qualified 
P.E. Finally, EPA proposed to require that the certified demonstration 
be completed and placed in the operating record no later than the 
effective date of this final rule.
---------------------------------------------------------------------------

    \58\ These impoundments contained both CCR and liquids on or 
after October 19, 2015, and subsequently completed closure of the 
impoundment before the effective date of this final rule.
---------------------------------------------------------------------------

    A number of commenters requested that EPA expand the certification 
to cover all State-approved closures by removal--including those in 
which all CCR was removed from the unit or site, but the State approved 
the closure without requiring any groundwater monitoring. The only 
factual basis these commenters offered to support their request was 
that EPA should rely on the State's determination that the closure was 
protective.
    Other commenters raised concern that the information needed to 
support a certification may not be readily available, and as a 
consequence these units would be subject to all of the other 
requirements of the final rule, including groundwater monitoring, 
preparation of plans, filing of reports, and closure and post-closure 
activities. These commenters stated such an outcome is not necessary to 
protect human health and the environment.
    Other commenters stated that the proposed closure certification 
under Sec.  257.100(f)(1)(ii) was not sufficient to allow EPA, States, 
and the public to determine whether the facility has actually complied 
with the closure performance standards under Sec.  257.102(c). These 
commenters requested that the final rule require owners/operators 
certifying closure by removal to specify, with supporting documentation 
all of the following:
     The nature and volume of CCR and all other materials in 
the unit prior to closure;
     All releases from the unit to the soil, surface water, 
groundwater, and atmosphere during the operation of the unit, during 
its inactive period(s), and prior to completion of closure activities;
     The nature and extent of all soil, groundwater, surface 
water, and other contamination associated with releases from the unit 
throughout its history, including active and inactive periods;
     The methods to be employed (in closure plans) and actually 
employed (in closure completeness certifications) to ensure complete 
removal of all CCR and other contaminated materials from the unit, 
including but not limited to post-removal sampling and analysis;
     Documentation that all CCR and other contaminated 
materials were in fact removed from the unit, including but not limited 
to post-removal sampling and analysis;

[[Page 39009]]

     The methods to be employed (in closure plans) and actually 
employed (in closure completeness certifications) to ensure complete 
decontamination of all areas affected by releases from the unit, 
including but not limited to post-decontamination sampling and 
analysis; and
     Documentation that all areas affected by releases from the 
unit were in fact decontaminated and that all groundwater affected by 
releases has achieved groundwater protection standards, including but 
not limited to a minimum of two years of post-removal/decontamination 
detection and assessment groundwater monitoring data collected pursuant 
to the CCR Rule's groundwater monitoring performance standards and 
analyzed pursuant to its sampling and analysis requirements, 40 CFR 
257.91 and 257.93, to reliably demonstrate compliance with groundwater 
protection standards in order to certify the completion of closure in 
accordance with 40 CFR 257.102(c).
    EPA is unable to adopt the commenters' suggestion to expand the 
certification to all State-approved closures by removal. Without any 
record of the factual and legal bases for the States' decisions, EPA 
cannot conclude that all State-approved closures by removal pose no 
reasonable probability of adverse effects on health or the environment, 
as it is required to do under RCRA section 4004(a). This is 
particularly true with respect to closures that were approved without 
any groundwater monitoring or other information to demonstrate that 
``groundwater . . . concentrations do not exceed the groundwater 
protection standard established pursuant to Sec.  257.95(h),'' 40 CFR 
257.102(c). Given the high probability that these impoundments were 
unlined and leaked, the most likely conclusion is that contamination 
remains at the site. In the absence of any further information, it is 
not apparent how EPA could support approving such closures in a 
nationwide rulemaking. See also Unit III.B.2.g.iii of this preamble for 
further discussion of State programs.
    EPA agrees that certifications under this paragraph need to include 
sufficient supporting data so that EPA, States, and the public can 
determine whether the facility has actually complied with the 
performance standards in Sec.  257.102(c). However, EPA disagrees that 
all of the information the commenters suggest is necessary to achieve 
that goal. As described below, the final rule requires that a facility 
support its certification with information that would have been 
routinely developed as part of closing the unit; either because the 
information is routinely required by State permit authorities or 
because the facility would have developed the information as part of 
the normal construction processes. Specifically, the final rule 
requires facilities to include the following supporting information 
with their certification:
    (1) The type and volume of CCR and all other materials in the unit 
prior to closure;
    (2) The methods used to verify complete removal of all CCR and 
other contaminated materials from the unit, including any post-removal 
sampling and analysis;
    (3) Documentation that all CCR and other contaminated materials 
were removed from the unit, including, the results of any post-removal 
sampling and analysis that was conducted;
    (4) The methods used to verify complete decontamination of all 
areas affected by releases from the unit, including but not limited to 
post-decontamination sampling and analysis; and
    (5) Documentation that all areas affected by releases from the unit 
were decontaminated and that all groundwater affected by releases has 
achieved groundwater protection standards.
    The final rule identifies the minimum information needed to support 
a certification, but, for the most part does not substantially restrict 
the analyses or factual information that can be used. This is because 
these units closed before they were subject to the Federal CCR 
regulations, or knew that they would be subject to the regulations, and 
EPA expects it is unlikely that facilities would necessarily have the 
same documentation as a currently regulated entity. State requirements 
specifying the information and analyses necessary to obtain approvals 
or permits can vary significantly. However, the final rule specifies 
that the facility must have groundwater monitoring data demonstrating 
that the concentrations of each Appendix IV constituent do not exceed 
the relevant groundwater protection standard, which would be either the 
MCL or background concentration, for two consecutive sampling events, 
consistent with Sec.  257.95(e). The final rule identifies the minimum 
information needed to support a certification, but does not 
substantially restrict the analyses or factual information that can be 
used. Because the facility was not subject to part 257 groundwater 
monitoring when the monitoring was conducted, the final rule does not 
require a facility to demonstrate that it had installed a groundwater 
monitoring system that complied with all of the requirements in 
Sec. Sec.  257.90 through 257.95. Nevertheless, the data supporting the 
certification must be scientifically valid and must credibly support a 
determination that the monitoring system would reliably detect any 
releases from the impoundment. Therefore, the final rule requires that 
owner or operator demonstrate that the groundwater monitoring system 
used to document the concentrations of Appendix IV constituents met a 
subset of the performance standards found in Sec. Sec.  257.91(a) 
through (e), 257.93(a) through (d), and 257.93(i). Specifically, the 
facility needs to demonstrate that the groundwater monitoring system 
met the following criteria:
    (1) Accurately represented background water quality unaffected by a 
CCR unit;
    (2) Accurately represented the quality of water passing the waste 
boundary of the unit;
    (3) Was capable of detecting contamination in the uppermost 
aquifer;
    (4) Monitored all potential contaminant pathways;
    (5) Established groundwater background concentrations for Appendix 
IV constituents and compared samples to those background 
concentrations; and
    (6) Utilized wells that are (a) cased and maintained in a manner 
that protects the integrity of the monitoring well borehole, (b) 
screened or perforated and packed with gravel or sand, where necessary, 
to enable collection of groundwater samples, and (c) sealed between the 
borehole and the well casing to prevent contamination of the sample and 
groundwater.
    Finally, the last sample used to demonstrate that no constituent in 
Appendix IV was detected in concentrations above the established 
groundwater protection standards must have been collected no earlier 
than one year prior to the initiation of closure.
    If a facility can certify that all legacy CCR surface impoundments 
on-site met the standards in Sec.  257.102(c) prior to the effective 
date of this rule, the facility would not be subject to any further 
requirements under this final rule (i.e., neither legacy CCR surface 
impoundment requirements or CCRMU requirements). For these units, the 
certification of closure by removal would be due no later than the 
effective date of this final rule and must be placed in the facility 
operating record then posted on their public CCR website. See Sec.  
257.100(g).
    EPA agrees that if a facility has actually met the performance 
standards

[[Page 39010]]

in Sec.  257.102(c), there is no health or environmental benefit in 
requiring compliance with all of subpart D simply because the facility 
lacks the information to support the certification. Accordingly, the 
final rule provides an option that allows such a facility to obtain the 
information necessary to support a certification. If a facility has 
removed all CCR from a legacy CCR surface impoundment before the 
effective date of this final rule but never conducted groundwater 
monitoring (or had a groundwater monitoring system that does not meet 
the criteria laid out above), the facility would initially only be 
required to install a groundwater monitoring system and initiate 
groundwater monitoring in accordance with the requirements in 
Sec. Sec.  257.90 through 257.95, as well as the recordkeeping, 
notification, and website posting requirements described in Units 
III.B.2.f and III.B.2.h. If the owner or operator of one of these units 
elects to pursue a closure certification, the owner or operator must 
prepare a notification of intent to certify closure by the effective 
date of this final rule and place it in the operating record, post it 
on their CCR website, and submit a notification to EPA or the State or 
Tribal Authority. The notification must state that the facility has 
removed all CCR from the unit and will be installing a groundwater 
monitoring system compliant with Sec. Sec.  257.90 through 257.95 to 
determine whether there is contamination coming from the unit. If no 
SSL above the GWPS is detected for all Appendix IV constituent in at 
least the first two consecutive sampling events, consistent with the 
existing provisions of Sec.  257.95(e), the facility could at that time 
complete the closure certification, and document compliance with Sec.  
257.102(c). EPA anticipates that the requirement to conduct two 
consecutive sampling events will result in one sample being taken 
during the dry season and one in the wet season and thus capture 
groundwater fluctuations. If the required sampling demonstrates no 
exceedances of Appendix IV constituents, the owner or operator of the 
unit must place the closure certification in the operating record, and 
submit a notification to the State or Tribal Authority, and post the 
certification documentation on their public CCR website. At that time, 
the facility would not be subject to any further requirements under 
this final rule (i.e., neither legacy CCR surface impoundment 
requirements or CCRMU requirements). The deadline for the completion of 
the certification of closure by removal for these units is no later 
than 42 months after the effective date of the final rule. This will 
provide the owner or operators of these units with the same amount of 
time as other legacy CCR surface impoundments to comply with the 
requirements to design and install a groundwater monitoring network, 
develop a sampling and analysis plan, collect eight baseline samples, 
and initiate combined detection and assessment monitoring (i.e., 30 
months after the effective date of the final rule) and an additional 12 
months to perform at least two sampling rounds.
    If, however, groundwater monitoring detects an SSL above the 
established GWPS of any Appendix IV constituent, the legacy CCR surface 
impoundment described above becomes subject to the corrective action 
requirements in Sec. Sec.  257.96 through 257.98 and is no longer 
eligible to certify closure by removal under this provision. The owner 
or operator of the legacy impoundment must then prepare the 
applicability report no later than six months from the date of 
receiving the laboratory analysis documenting the SSL. No later than 
eight months from the date of receiving the laboratory analysis 
documenting the exceedance of the GWPS, the owner or operator must 
install the permanent marker. Furthermore, the facility must comply 
with the CCRMU requirements in Unit III.C. However, the compliance 
deadlines for the CCRMU requirements will be delayed by the number of 
months between the publication date of the rule and the date of 
receiving the laboratory analysis documenting the exceedance of the 
groundwater protection standard. For example, if a facility receives 
the laboratory analysis documenting an exceedance of the GWPS for any 
Appendix IV constituent 36 months after the effective date, the 
facility would add 42 months to all the CCRMU compliance deadlines. 
Additionally, if a CCRMU is discovered onsite, the owner or operator 
must prepare a fugitive dust plan no later than 6 months after the 
completion of the FER. For such units that are unable to certify, the 
final rule also includes a provision that allows a facility closing a 
unit by removal to complete any necessary corrective action during a 
post closure care period. Assuming the criteria in Unit III.B.2.g.iii 
are met, the facility can also elect to defer closure to permitting. 
However, given that the facility must comply with the groundwater 
monitoring and corrective actions under both options, EPA expects that 
most facilities will prefer to pursue certifications. See Unit III.D of 
this preamble for further discussion.
c. Location Restrictions and Liner Design Criteria
    Under the existing CCR regulations, existing CCR surface 
impoundments that cannot demonstrate compliance with the location 
restrictions for placement of CCR above the uppermost aquifer, in 
wetlands, within fault areas, in seismic impact zones, or in unstable 
areas (specified in Sec. Sec.  257.60 through 257.64) must retrofit or 
close. The purpose of these requirements is to ensure that units 
located in particularly problematic areas cease operation. EPA 
explained in the proposed rule that because, by definition, legacy CCR 
surface impoundments are not operating, and because it appears that all 
legacy CCR surface impoundments are unlined and will therefore be 
required to close, EPA believed that requiring compliance with the 
location restrictions would be largely redundant.
    Commenters largely supported not requiring location restrictions or 
liner demonstrations on the grounds that location restrictions and 
design criteria are not relevant to this class of units, as these 
requirements primarily seek to ensure active units operate safely. 
Other commenters believed that legacy CCR surface impoundments should 
not be exempted from liner and structural stability requirements out of 
concern that requiring compliance with one or more location 
restrictions would provide information that would be ``critical'' to 
designing unit closure and any necessary corrective action.
    EPA disagrees that applying location restrictions and the liner 
design criteria to legacy CCR surface impoundments would be 
appropriate. First, as explained in the proposed rule, these criteria 
are more appropriate for operational units or units at active 
facilities. Second the consequence of failing to comply with the 
location restrictions and liner design criteria requirements is closure 
by a specific date. 40 CFR 257.101(a) through (b)(1). Because legacy 
CCR surface impoundments are not operational and will in any event be 
required to close, the consequence for failure to comply with location 
restrictions or the liner design criteria (i.e., ceased receipt of 
waste and closure) is moot. Additionally, the commenter failed to 
identify any information necessary for conducting corrective action or 
closure uniquely gained by complying with the location restrictions or 
liner design criteria. Therefore, EPA continues to conclude that, as 
stated in the proposed rule, information useful for corrective

[[Page 39011]]

action or closure that would be obtained by complying with the location 
restrictions will be captured by compliance with the history of 
construction requirement, the closure plan, or in the development of 
the groundwater monitoring system.
    EPA also continues to believe that the requirement to document 
whether the impoundment was constructed with a composite liner or 
alternative composite liner under Sec.  257.71(a)(1) is not warranted 
for legacy CCR surface impoundments. The original purpose of this 
provision was to determine whether the unit was unlined, and 
consequently subject to closure. However, the available information 
indicates that legacy CCR surface impoundments were largely constructed 
well before composite liners systems were typically installed. Indeed, 
no commenter identified a legacy impoundment with a composite liner. 
For these reasons, EPA expects legacy CCR surface impoundment to be 
unlined and, therefore, the final rule requires all legacy CCR surface 
impoundments to close. As a consequence, requiring facilities to 
compile the information required by Sec.  257.71(a)(1) would not 
provide useful information or otherwise be necessary. Therefore, EPA is 
not finalizing such requirement.
d. Design Criteria for Structural Integrity for Legacy CCR Surface 
Impoundments
    EPA proposed that legacy CCR surface impoundments be subject only 
to the existing design criteria requirements in Sec.  257.73, in order 
to help prevent damages associated with structural failures of CCR 
surface impoundments.
    EPA received numerous comments on application of the design 
criteria requirements to legacy CCR surface impoundments. Most 
commenters on the design criteria specifically commented on the 
reporting/assessment requirements in Sec.  257.73 (i.e., history of 
construction, initial hazard potential classification, initial 
structural stability assessment, initial safety factor assessment). 
Some of these commenters supported the expedited deadline for the 
reports. However, most of these commenters echoed the concerns 
mentioned in Unit III.B.2.a.ii of this preamble, characterizing the 
proposed deadlines as infeasible, citing third-party availability, 
national labor shortage, seasonality, the need to conduct quality 
control and quality assurance, and the accessibility and completeness, 
or lack thereof, of historical documentation and data. These commenters 
stated that because legacy CCR surface impoundments are not operational 
and have not been operational since before the 2015 CCR Rule took 
effect, it is highly unlikely that owners or operators will have the 
required historical documentation or data readily available and that, 
for most of these facilities, documentation is likely in storage or 
lost to time. Commenters have stated that more time is needed for 
owners or operators to do their due diligence in locating and reviewing 
the necessary data and information.
    Furthermore, these commenters stated that due to the likely lack of 
historical information, additional analyses will more than likely be 
necessary to collect information essential to meeting the standards in 
the CCR rule for each report. Additionally, these commenters said that 
EPA was incorrect in characterizing these additional analyses as minor 
and capable of being performed within the proposed deadline (i.e., 
three months from the effective date of the final rule) and that some 
of these analyses (e.g., site visits, geotechnical investigations) 
could be impacted by both contractor availability and seasonality. 
Several commenters also pointed out that Professional Engineer (P.E.) 
certification or approval by the Participating State Director or EPA 
was required for these reports (i.e., hazard potential classification 
assessments, structural stability assessments, and safety factor 
assessments). These commenters said that the proposed deadline did not 
provide adequate time to collect and review historical information, 
acquire any necessary new information (i.e., perform additional 
analyses), and conduct sufficient quality control and quality assurance 
of said information to ensure the report would be certifiable by a P.E. 
or capable of being approved by a State Director, Tribal authority, or 
EPA. Commenters also highlighted that the information required by Sec.  
257.73 will also be important in complying with concurrent and 
subsequent requirements, such as the design of the groundwater 
monitoring network and the closure plan. These commenters stated that 
providing inadequate time to generate reports under Sec.  257.73 that 
meet the standards set out in the rule has an adverse ripple effect on 
the inputs of other requirements, undermining the adequacy of those 
analyses and plans. Lastly, commenters stated the estimates in the 
proposed rule of the amount of time needed to complete actions 
necessary to achieve compliance (e.g., hire a contractor; generate a 
report) were grossly underestimated, based on the experiences of 
engineering firms, consultants, and owners or operators.
    No commenters raised concern about requiring legacy impoundments to 
comply with the existing requirements in Sec.  257.73. Therefore, EPA 
is finalizing the application of the structural integrity requirements 
in Sec.  257.73 to legacy CCR surface impoundments.
    As mentioned in Unit III.B.2.a.ii of this preamble, based on the 
information provided by commenters regarding the impacts of third-party 
availability, national labor shortage, seasonality, and accessibility 
and completeness of historical documentation, EPA has extended the 
deadlines for the design criteria located at Sec.  257.73 as described 
below. This is at least as much time as facilities were granted to 
reach compliance in the 2015 CCR Rule deadlines. As detailed below in 
Units III.B.d.i through III.B.d.v, EPA calculates that this additional 
time as compared to the proposed deadlines mitigates the seasonality 
concerns associated with performing any necessary analyses involving 
field work; accommodates for the unavoidable delays caused by backlogs 
and shortages currently being faced by necessary third parties; 
provides owners or operators time to locate and compile the relevant 
historical documentation that was more readily available and accessible 
for facilities complying with the 2015 CCR Rule; and ensures a 
compliance deadline feasible for facility nationwide.
i. Installation of a Permanent Marker for Legacy CCR Surface 
Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments, except for ``incised CCR surface impoundments'' as 
defined in Sec.  257.53, comply with Sec.  257.73(a)(1), which requires 
the placement of a permanent identification marker, at least six feet 
high on or immediately adjacent to the CCR unit. EPA also proposed that 
placement of the permanent marker be completed by the effective date of 
the final rule.
    Overall, commenters stated this deadline should align with the 2015 
CCR Rule deadline (i.e., two months from the effective date) to 
accommodate for site access issues, seasonality, and the time needed to 
hire necessary third parties to conduct the work. EPA acknowledges that 
the proposal had not accounted for the national labor shortage of 
contractors, or the need to factor in seasonality for site access and 
the installation of the permanent marker. Therefore, EPA agrees with 
the commenters that extending the deadline for the installation of the 
permanent marker to no later than two months from

[[Page 39012]]

the effective date of the final rule provides owners or operators of 
legacy CCR surface impoundments would provide the necessary time to 
comply with the requirement at Sec.  257.73(a)(1) while still being 
protective of human health and the environment.
    Therefore, EPA is finalizing the requirement to install the 
permanent marker no later than Wednesday, January 8, 2025, which is two 
months after the effective date of the final rule. This is codified in 
the regulatory text at Sec.  257.100(f)(2)(i).
    To complete the installation of the permanent marker, owners or 
operators must ensure the marker is at least six feet high and displays 
the name of the legacy CCR surface impoundment, the name of the owner 
or operator of the unit, and the identification number of the CCR unit, 
if one has been assigned by the State.
ii. History of Construction for the Legacy CCR Surface Impoundments
    Consistent with the existing regulations, EPA proposed that owners 
or operators of legacy CCR surface impoundments that either have: (1) A 
height of five feet or more and a storage volume of 20 acre-feet or 
more; or (2) Have a height of 20 feet or more, would be required to 
comply with the existing requirements to compile the history of 
construction of the legacy CCR surface impoundment. In the proposed 
rule, EPA acknowledged that information regarding construction 
materials, expansions or contractions of units, operational history, 
and history of events may be difficult for owners or operators to 
obtain. Therefore, EPA proposed that owners or operators would only 
need to provide information on the history of construction to the 
extent that such information is reasonably and readily available. EPA 
proposed a deadline of no later than three months after the effective 
date for owners or operators to comply with this requirement.
    Overall, commenters on the proposed rule stated the proposed 
deadline for the history of construction was infeasible for the reasons 
listed in Unit III.B.2.d of this preamble; namely the limited 
availability of contractors, exacerbated by the number of CCR units 
competing for the same resources; seasonality impacts on necessary 
analyses; and accessibility and completeness of historical information. 
Some of these commenters also highlighted the importance of the history 
of construction requirement as an input into the design of the 
groundwater monitoring system, closure decisions, and other design 
criteria assessments; these commenters further emphasized the direct 
impacts of the quality of the history of construction on the quality of 
subsequent (i.e., groundwater monitoring network design, closure plan) 
and interrelated requirements (i.e., hazard potential classification, 
structural stability and safety factor assessments, inflow design flood 
control system plan, EAP). These commenters said that, although EPA 
acknowledged in the proposed rule that EPA would only require 
information that is reasonably and readily available, owners or 
operators would still likely need to conduct surveys and other analyses 
to ensure the report would meet the requirements in Sec.  257.73(a)(2) 
and to provide sufficient information for the completion of subsequent 
and interrelated requirements. These commenters also stated that 
locating the necessary documentation to complete the history of 
construction would take considerable time and effort due to the age of 
the units, the inactivity of the facility, and the likelihood of 
records being located at currently unknown offsite locations. 
Furthermore, some of these commenters requested clarification of what 
EPA means by ``reasonably and readily available.'' Finally, commenters' 
suggested deadlines for the completion of the history of construction 
requirement ranged from three to 30 months.
    As stated in Unit III.B.2.d of this preamble, EPA has reviewed the 
information provided by commenters citing the shortages and backlogs of 
qualified contractors, increased strain on those contractors related to 
the number of CCR units complying with the CCR rule simultaneously, 
difficulty accessing and reviewing historical documentation, and needed 
time to perform quality control and quality assurance, and considers it 
to be persuasive. EPA also acknowledges that the history of 
construction report ties into several subsequent requirements, 
including the other design criteria assessments and plan, the 
groundwater monitoring and corrective action requirements, and the 
closure and post-closure care requirements and therefore, agrees that 
providing sufficient time for the completion of a thorough history of 
construction report is important for the protection of human health and 
the environment.
    Furthermore, as stated in Unit III.B.2.a.ii, EPA extended most 
deadlines to allow for as much time to come into compliance as was 
granted in the 2015 CCR Rule. While EPA recognizes that when coming 
into compliance with the 2015 CCR Rule, owners and operators had to 
locate historical documentation, based on information provided by 
commenters regarding the unknown whereabouts of the necessary records, 
the age and inactivity of these facilities, and the labor shortages, 
EPA expects it will be slightly more difficult to access and assess 
historical documentation for the older legacy CCR surface impoundments 
than it was for the units regulated by the 2015 CCR Rule. Because of 
the increased difficulty in locating and accessing records, the 
importance of the history of construction as an input into other 
requirements, and the high likelihood of additional analyses being 
needed, EPA is finalizing a deadline of no later than Monday, February 
9, 2026, which is 15 months from the effective date. This deadline is 
an extension of three months longer than the 2015 CCR Rule deadline and 
is sufficient to accommodate the slight increase in difficulty in 
accessing legacy impoundment records. This is codified in the 
regulatory text at Sec.  257.100(f)(2)(ii).
    Finally, as explained in Unit III.B.2.b.i, EPA addressed the term 
``reasonably and readily available'' at 80 FR 21380. When using this 
term, EPA intends facilities to provide relevant design and 
construction information only if factual documentation exists and does 
not expect owners or operators to generate new information or provide 
anecdotal or speculative information.
    Compliance with the history of construction requirement at Sec.  
257.73(c) requires owners or operators of a CCR unit to compile a 
report that documents identifying characteristics of the unit, the 
history of how the CCR unit was used, specifics related to the unit's 
design and construction, and the unit's instrumentation. Once compiled, 
the report must be placed into the facility's operating record as 
required by Sec.  257.105(f)(9). If the information included in the 
history of construction report needs to be changed at any point in 
time, the owner or operator must update the history of construction 
report and place the updated report into the operating record. A 
comprehensive list of information required in the history of 
construction is in Sec.  257.73(c)(1).
iii. Initial Hazard Potential Classification for Legacy CCR Surface 
Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments, except for incised CCR surface impoundments as defined in 
Sec.  257.53, must complete the initial and periodic hazard potential 
classification assessments required under Sec.  257.73(a)(2) without 
revision. EPA

[[Page 39013]]

proposed a deadline of no later than three months after the effective 
date for the completion of the initial hazard potential classification 
assessment.
    No commenters raised concern about requiring legacy impoundments to 
comply with the existing requirements in Sec.  257.73(a)(2). EPA is 
therefore finalizing this provision without revision. This is codified 
in the regulatory text at Sec.  257.100(f)(2)(iii).
    However, EPA received numerous comments on the proposed deadline. 
Overall, commenters on the proposed rule stated the proposed deadline 
for the initial hazard potential classification was infeasible for the 
reasons listed in Unit III.B.2.d of this preamble, namely the limited 
availability of contractors exacerbated by the number of CCR units 
competing for the same resources; seasonality impacts on necessary 
analyses; accessibility and completeness of historical information, and 
the need for quality assurance and quality control. As mentioned in 
Unit III.B.2.d.ii, a few commenters noted the interrelationship and 
overlapping activities (e.g., historical documentation review, site 
visit, geotechnical investigations, unit modeling) between the initial 
hazard potential classification and the history of construction, 
initial safety factor assessment, and the initial structural stability 
assessment. Specifically, commenters stated that the history of 
construction is done first and used to complete the initial hazard 
potential classification. Furthermore, commenters highlighted the 
direct dependence on the hazard potential classification for 
determining the design flood to use in inflow design flood control plan 
(Sec.  257.82(c)) and the trigger for the EAP requirement (Sec.  
257.73(a)(3)). Commenters' suggested deadlines for the completion of 
the hazard potential classification requirement ranged from three to 24 
months.
    As explained in Units III.B.2.a.ii and III.B.2.d of this preamble, 
EPA acknowledges the need to extend the compliance deadline in 
consideration of the impacts of labor shortage, contractor backlogs, 
seasonality, accessibility and completeness of historical information, 
and the need for quality assurance and control. EPA further 
acknowledges the interrelationship of the design criteria reports and 
the direct dependence of the initial inflow design plan and EAP 
requirements on the completion of hazard potential classification. As 
explained in Unit III.B.2.d of this preamble, based on the information 
provided by commenters, EPA determined that extending the deadline for 
the initial hazard potential classification to allow for at least as 
much time to come into compliance as was granted in the 2015 CCR Rule 
(i.e., 18 months after the effective date) is necessary to ensure the 
compliance deadlines are nationally feasible. Because owners or 
operators will be locating and compiling historical documents and 
information as part of the history of construction requirement, EPA 
assumes that historical documentation necessary for the initial hazard 
potential classification assessment can be located and compiled 
concurrently. Additionally, EPA expects necessary historical 
information (e.g., engineering design drawings, geotechnical studies, 
dam hazard potential classification documents, stability assessments) 
and new analyses (e.g., surveys or geotechnical investigations) needed 
for the history of construction and the initial hazard potential 
classification to overlap to some degree. Therefore, EPA has determined 
that additional time beyond that granted to come into compliance with 
the 2015 CCR Rule is not needed for this requirement. As such, EPA is 
finalizing a deadline of no later than Friday, May 8, 2026, which is 18 
months from the effective date of this final rule.
    To comply with the hazard potential classification requirement at 
Sec.  257.73(a)(2), owners or operators of legacy CCR surface 
impoundments must determine the hazard potential classification of the 
CCR unit and justify the determination in a report. The CCR unit can be 
classified as a low hazard potential CCR surface impoundment, a 
significant hazard potential CCR surface impoundment, or a high hazard 
potential CCR surface impoundment. The report must be certified by a 
P.E. stating the hazard potential classification was conducted in 
accordance with the CCR regulations. Subsequent periodic hazard 
potential classifications are required every five years after the 
completion of the previous hazard potential classification as described 
at Sec.  257.73(f)(3).
iv. Initial Structural Stability Assessment and Initial Safety Factor 
Assessment for Legacy CCR Surface Impoundments
    Consistent with the existing regulations and EPA's findings from 
the 2009-2014 Assessment Program as described in the proposed rule, EPA 
proposed that owners or operators of legacy CCR surface impoundments 
that meet the size thresholds in Sec.  257.73(b) and (c), must conduct 
two types of technical assessments: (1) Structural stability 
assessments; and (2) Safety factor assessments. In the proposed rule, 
EPA explained that these two assessments could be conducted 
concurrently and therefore, a deadline of no later than three months 
from the effective date of the final rule was proposed for both 
requirements.
    No commenters raised concern about requiring legacy impoundments to 
comply with the existing requirements in Sec.  257.73(b) and (c). EPA 
is therefore finalizing this provision without revision. This is 
codified in the regulatory text at Sec.  257.100(f)(2)(iv).
    However, EPA received numerous comments on the proposed deadline. 
Overall, commenters on the proposed rule stated the proposed deadlines 
for the initial structural stability and safety factor assessments were 
infeasible for the reasons outlined in Units III.B.2.a.ii and III.B.2.d 
of this preamble, namely, seasonality, third-party availability, 
national labor shortage, the need to conduct quality control and 
quality assurance, and the accessibility and completeness, or lack 
thereof, of historical documentation and data. As mentioned in Unit 
III.B.2.d.ii, a few commenters noted the interrelationship and 
overlapping activities (e.g., historical documentation review, site 
visit, geotechnical investigations, unit modeling) between the initial 
structural stability and safety factor assessments and the history of 
construction, initial hazard potential classification, and the inflow 
flood control system plan. Furthermore, commenters highlighted the need 
to have quality information within the structural stability and safety 
factor assessments to inform the EAP and to make sound closure 
decisions. Commenters' suggested deadlines for the completion of the 
initial structural stability assessment and the initial safety factor 
assessment ranged from six to 24 months.
    As explained in Units III.B.2.a.ii and III.B.2.d, EPA acknowledges 
the need to extend the compliance deadline in consideration of the 
impacts of labor shortage, contractor backlogs, seasonality, 
accessibility and completeness of historical information, and the need 
for quality assurance and control. EPA further acknowledges the 
interrelationship of the design criteria reports and the value of using 
the structural stability and safety factor assessment to develop the 
EAP and the closure plan for the legacy CCR surface impoundment. As 
explained in Unit III.B.2.d of this preamble, based on the information 
provided by commenters, EPA determined that extending the deadline for 
the initial structural stability and safety factor assessments to allow 
for at least as much time to come into compliance as was granted in the

[[Page 39014]]

2015 CCR Rule is necessary to ensure the compliance deadlines are 
nationally feasible. Because owners or operators will be locating and 
compiling historical documents and information as part of developing 
the history of construction, EPA assumes that historical documentation 
necessary for the initial structural stability and safety factor 
assessments can be located and compiled concurrently. Additionally, the 
historical information (e.g., engineering design drawings, operational 
records) and new analyses (e.g., surveys, geotechnical investigations) 
needed for the history of construction, initial hazard potential 
classification, and the initial structural stability and safety factor 
assessments overlap to some degree. Therefore, EPA has determined that 
additional time beyond that granted to come into compliance with the 
2015 CCR Rule is not needed for this requirement. As such, EPA is 
finalizing a deadline of no later than Friday, May 8, 2026, which is 18 
months from the effective date of this final rule.
    To comply with the structural stability assessment and safety 
factor assessment requirements at Sec.  257.73(d) and Sec.  257.73(e), 
owners or operators of legacy CCR surface impoundments must conduct 
initial and periodic structural stability and safety factor 
assessments. The structural stability assessment must document whether 
the design, construction, operation, and maintenance of the unit is 
consistent with recognized and generally accepted good engineering 
practices for the maximum volume of CCR and CCR wastewater capable of 
being contained within the unit. Accepted good engineering practices 
includes, but are not limited to, stable foundations and abutments, 
adequate slope protection, sufficiently compacted dikes, slope 
protections, spillways capable of managing flow during and following 
peak discharge events, structurally sound and operational hydraulic 
structures, and structurally sound downstream slopes capable of 
withstanding sudden drawdown of adjacent water bodies. See 40 CFR 
257.73(d).
    The safety factor assessment must document whether the calculated 
factors of safety for the legacy CCR surface impoundment achieves the 
minimum safety factor specified in Sec. Sec.  257.73(e)(1)(i) through 
(iv) for the cross section of the embankment most susceptible to 
structural failure determined by loading conditions and other 
appropriate engineering considerations. See 40 CFR 257.73(e).
    The periodic assessments are required every five years after the 
completion of the previous assessment described at Sec.  257.73(f)(3). 
Each assessment must be certified by a P.E. stating that the assessment 
was conducted in accordance with the CCR regulations.
v. Preparation of an Emergency Action Plan for Legacy CCR Surface 
Impoundments
    EPA proposed that the owners or operators of legacy CCR surface 
impoundments that have been identified as having either a high hazard 
potential or a significant hazard potential would be required to comply 
with the same requirement as existing CCR surface impoundments under 
Sec.  257.73 to prepare and maintain a written EAP. An EAP is a 
document that identifies potential emergency conditions at a CCR 
surface impoundment and specifies actions to be followed to minimize 
loss of life and property damage.
    No commenters raised concern about requiring legacy impoundments to 
comply with the existing requirements in Sec.  257.73(a)(3). EPA is 
therefore finalizing this provision without revision. This is codified 
in the regulatory text at Sec.  257.100(f)(2)(v).
    However, EPA received numerous comments on the proposed deadline. 
Overall, most commenters on the proposed rule stated that at a minimum, 
EPA should allow as much time for legacy CCR surface impoundment to 
come into compliance as granted existing units the 2015 CCR Rule 
deadlines. Several commenters pointed out the direct reliance of the 
EAP on the hazard potential classification assessment and noted that 
the history of construction, safety factor assessment, and structural 
stability assessment provided critical information as well. These 
commenters noted that if the deadlines for any of those prerequisite 
requirements were extended beyond the proposed compliance deadline, the 
EAP deadline should be extended as well. Commenters' suggestions for 
the deadline for the completion of the EAP ranged from 11 to 18 months.
    EPA acknowledges that the EAP relies on the hazard potential 
classification assessment and agrees with the commenters who stated 
that if the deadline for the hazard potential classification assessment 
was extended, the deadline for the development of the EAP should be 
extended to no earlier than the deadline for the initial hazard 
potential classification assessment. As stated in Unit III.B.2.d.iv, 
EPA is finalizing a deadline of no later than 18 months from the 
effective date of this final rule for the initial hazard potential 
classification assessment. Furthermore, the deadlines for the initial 
safety factor and structural stability assessments are being finalized 
at no later than Friday, May 8, 2026, which is 18 months from the 
effective date of the final rule. This deadline also provides owners or 
operators the same amount of time for legacy CCR surface impoundments 
to comply with the requirements as was granted for existing units in 
the 2015 CCR Rule. Therefore, EPA is finalizing a deadline of no later 
than Friday, May 8, 2026, which is 18 months from the effective date of 
the final rule for legacy CCR surface impoundment to develop an EAP in 
accordance with Sec.  257.73(a)(3).
    As described above, an EAP specifies the actions to take during 
potential emergency conditions at a CCR surface impoundment. To prepare 
an EAP, the owner or operator must accurately and comprehensively 
identify potential failure modes and at-risk developments. See also 80 
FR 21377-21379, April 17, 2015. To comply with the EAP requirement, the 
EAP must, at a minimum, define the events or circumstances involving 
the CCR unit that represent a safety emergency; describe the procedures 
that will be followed to detect a safety emergency in a timely manner; 
define responsible persons, each person's responsibilities, and 
notification procedures in the event of an emergency; provide contact 
information for emergency responders; include a map that delineates the 
downstream area that would be impacted by a CCR unit failure; a 
physical description of the CCR unit; and provisions for an annual 
face-to-face meeting between representatives of the owner or operator 
and the local emergency responders.
e. Operating Criteria for Legacy CCR Surface Impoundments
    The operating criteria in Sec. Sec.  257.80, 257.82, and 257.83 
include air criteria for all CCR units, hydrologic and hydraulic 
capacity requirements for CCR surface impoundments, and periodic 
inspection requirements for CCR surface impoundments. These criteria 
address the potential risks from the day-to-day operations of CCR units 
and are established to prevent health and environmental impacts from 
CCR units. CCR surface impoundments are subject to hydrologic and 
hydraulic capacity requirements to ensure the unit can safely handle 
flood flows, which will help prevent uncontrolled overtopping of the 
unit or erosion of the materials used to construct the surface 
impoundment. The existing CCR

[[Page 39015]]

regulations also require periodic inspections of CCR units to identify 
any appearance of structural weakness or other conditions that are not 
consistent with recognized and generally accepted good engineering 
standards. EPA proposed that legacy CCR surface impoundments comply 
with these existing requirements without revision.
    Several commenters recommended that EPA provide relief from these 
operating requirements for legacy impoundments that have closed prior 
to the effective date of this rule, since these operating requirements 
do not make sense for units that are no longer operating. These 
commenters also state that the proposed rule includes relief from many 
requirements for legacy impoundments that have closed by removal of 
CCR, but does not include similar flexibility for legacy impoundments 
that have closed in place. Commenters said requiring an owner or 
operator to meet operating requirements for units that no longer 
contain both CCR and liquids, and therefore do not pose the same 
operating risks as existing CCR units, is illogical. They contended 
these requirements are more applicable for legacy impoundments that 
continue to contain both CCR and liquids as of the effective date of 
this final rule. They further said EPA should therefore reconsider its 
position and account for prior closure activities and afford 
flexibility to those units that have undergone, or are undergoing, 
State-led closure activities.
    EPA disagrees that applying the operating criteria to legacy CCR 
surface impoundments is inappropriate even if these units are no longer 
receiving waste. EPA believes that applying the fugitive dust 
requirements reduces the risk from airborne dust and requiring 
inspections and inflow design flood control plan for legacy 
impoundments that contain both CCR and liquids will reduce the risks 
from structural stability concerns. EPA further addresses legacy 
impoundments that closed by removal or closed with waste in place under 
a State or Federal authority in Unit III.B.2.g of this preamble. 
Accordingly, EPA is finalizing the requirement that legacy CCR surface 
impoundments comply with these existing operating criteria requirements 
in Sec. Sec.  257.80, 257.82, and 257.83 without revision.
i. Fugitive Dust Control Plan for Legacy CCR Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments must complete a fugitive dust control plan by the 
effective date of the final rule. The existing regulations require the 
owner or operator of a CCR unit to adopt measures that will effectively 
minimize CCR from becoming airborne at the facility, including CCR 
fugitive dust originating from CCR units, roads, and other CCR 
management and material handling activities. 40 CFR 257.80(b). To meet 
this requirement, the owner or operator of the CCR unit must prepare 
and operate in accordance with a fugitive dust control plan. Id. See 
also 80 FR 21386-21388. EPA considers that fugitive dust controls are 
warranted because closure activities can produce significant quantities 
of dust.
    EPA received few comments on the fugitive dust control plan. One 
commenter requested that EPA amend Sec.  257.80 to include additional 
requirements to protect those who work or live near CCR facilities from 
the risks of fugitive dust. EPA disagrees that additional fugitive dust 
controls are needed as EPA has no data to prove that the existing 
requirements are inadequate.
    EPA received some comments on the compliance deadline to complete 
the fugitive dust control plan. Overall, commenters supported the 
proposed deadline. However, a couple commenters requested more time. 
One commenter requested three additional months for all requirements 
due on the effective date, including the fugitive dust plan. This 
commenter provided no evidence or factual basis to support this 
suggested deadline. Another commenter requested a deadline of 30 months 
for all requirements with proposed deadlines of the effective date to 
allow owners or operators 24 months to determine if the unit is 
eligible for the closure certification and prepare the certification 
report and then an additional 6 months to comply with other 
requirements, such as the dust plan and creation of a CCR website, if 
the unit is not eligible for the closure certification. EPA finds the 
requests for a deadline extension for the fugitive dust control plan to 
be unfounded.
    The primary activities associated with this requirement are hiring 
a contractor who is a qualified P.E., having the contractor develop a 
plan based on daily operations at the unit and site conditions, and 
certification of the plan by a P.E. Little to no field-based activities 
are required to complete the fugitive dust control plan. Furthermore, 
this provides the same amount of time that EPA provided in the 2015 CCR 
Rule for facilities to develop their fugitive dust control plans. 
Therefore, EPA is finalizing the requirement that owners or operators 
of legacy CCR surface impoundments must complete a fugitive dust 
control plan no later than Friday, November 8, 2024, which is the 
effective date of this final rule. This is codified in the regulatory 
text at Sec.  257.100(f)(3)(i).
ii. Initial Fugitive Dust Control Report for Legacy CCR Surface 
Impoundments
    EPA proposed to require the initial annual fugitive dust report to 
be due 12 months after the effective date of the final rule. Consistent 
with the existing regulations, the report must document all actions 
taken to control CCR fugitive dust, a record of all citizen complaints, 
and a summary of any corrective measures taken in the previous year. As 
this report is primarily a summary of owner or operator activities 
related to fugitive dust control and does not require a P.E. 
certification, the report may be completed by the owner or operator 
without the need for a contractor. The owner or operator has completed 
the annual CCR fugitive dust control report when the plan has been 
placed in the facility's operating record.
    EPA did not receive comments on the annual fugitive dust control 
report requirements. As described in Unit III.B.2.a.ii of this 
preamble, commenters requested that deadlines provide at least as much 
time as was granted for 2015 CCR Rule requirements. Therefore, EPA is 
extending the deadline from 12 months to 14 months to allow for a full 
year to be reported in the first report (12 months plus two months for 
report generation).
    EPA is finalizing the requirement that the initial annual fugitive 
dust report be completed no later than Thursday, January 8, 2026, which 
is 14 months after the effective date of this final rule. This is 
codified in the regulatory text at Sec.  257.100(f)(3)(vi).
iii. Weekly Inspections of the Legacy CCR Surface Impoundment and 
Monthly Monitoring of the CCR Unit's Instrumentation
    EPA proposed that owners or operators of legacy CCR surface 
impoundments must initiate the inspection requirements set forth in 
Sec.  257.83(a) no later than the effective date of the final rule. 
Under Sec.  257.83(a), all CCR surface impoundments must be examined by 
a qualified person at least once every seven days for any appearance of 
actual or potential structural weakness or other conditions that are 
disrupting or that have the potential to disrupt the operation or 
safety of the CCR unit. The results of the inspection by a qualified 
person must be recorded in the facility's operating record. Weekly 
inspections are intended to detect, as early as practicable, signs of 
distress in a CCR surface

[[Page 39016]]

impoundment that may result in larger, more severe conditions. 
Inspections are also designed to identify potential issues with 
hydraulic structures that may affect the structural safety of the unit 
and impact its hydraulic and hydrologic capacity. Section 257.83(a) 
also requires the monitoring of all instrumentation supporting the 
operation of the CCR unit to be conducted by a qualified person no less 
than once per month. See also 80 FR 21394-21395.
    One commenter opposed applying the inspection requirements to 
legacy CCR surface impoundment, stating these requirements are intended 
for operational units and therefore are inappropriate for units that no 
longer receive waste. EPA disagrees that applying the inspection 
requirements to legacy CCR surface impoundments is inappropriate even 
if these units are no longer receiving waste. EPA believes that 
applying the weekly inspection requirements to legacy CCR surface 
impoundments that contain both CCR and liquids reduces the risks 
associated with structural stability concerns. Furthermore, the 
commenter provided no factual basis for the exclusion of legacy CCR 
surface impoundments from these requirements. EPA did not get any 
comments specifically about this deadline, thus, EPA is finalizing 
without revision the requirement that owners or operators of legacy CCR 
surface impoundments initiate the inspection requirements set forth in 
Sec.  257.83(a) no later than Friday, November 8, 2024, which is the 
effective date of the final rule. This is codified in the regulatory 
text at Sec.  257.100(f)(3)(iii).
iv. Initial Annual Inspection for Legacy CCR Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments must conduct the initial annual inspection no later than 
three months after the effective date of the final rule. Existing CCR 
surface impoundments exceeding the height and storage volume thresholds 
in Sec.  257.73(b) and (c), are required to conduct annual inspections 
of the CCR unit throughout its operating life (Sec.  257.83(b)). These 
inspections are focused primarily on the structural stability of the 
unit and must ensure that the operation and maintenance of the unit is 
in accordance with recognized and generally accepted good engineering 
standards. Each inspection must be conducted and certified by a P.E. 
See also 80 FR 21395.
    EPA received comments that said the inspections should be required 
for legacy impoundments, in addition to the other operating criteria. 
However, one commenter opposed applying the inspection requirements to 
legacy CCR surface impoundment, stating these requirements are intended 
for operational units and therefore are inappropriate for units that no 
longer receive waste. EPA continues to conclude that the annual 
inspections required by Sec.  257.83 are relevant for legacy CCR 
surface impoundments even if these units are no longer receiving waste. 
EPA believes that applying the annual inspection requirement to legacy 
CCR surface impoundments that contain both CCR and liquids reduces the 
risks associated with structural stability concerns. Furthermore, the 
commenter provided no factual basis for the exclusion of legacy CCR 
surface impoundments from these requirements.
    Annual inspections include documentation review, a visual 
inspection of the CCR unit, and a visual inspection of any hydraulic 
structures underlying the base of the CCR unit or passing through the 
CCR unit's dike. Documentation reviewed as part of the annual 
inspection include operating records, previous structural stability 
assessments, and the results of previous weekly, monthly, and annual 
inspections and can overlap with reviews needed to complete the initial 
structural stability assessment.
    EPA proposed that owners or operators of legacy CCR surface 
impoundments must conduct the initial annual inspection no later than 
three months after the effective date of the final rule. EPA proposed 
that owners or operators must prepare the initial inspection report for 
legacy CCR surface impoundments within the same time frame--no later 
than three months from the effective date of the final rule--as was 
required for existing CCR surface impoundments in the 2015 CCR Rule. 
The Agency believes this time frame to prepare the initial annual 
inspection is similarly appropriate for legacy CCR surface impoundments 
as for existing impoundments. As discussed in the preamble to the 2015 
CCR Rule, the three-month time frame was based on EPA's experience with 
its CCR Assessment Program to evaluate the structural stability and 
safety of existing impoundments throughout the nation. Specifically, 
EPA found that three months would be adequate to complete the tasks 
supporting an annual inspection, including retaining the services of a 
P.E., reviewing relevant information in the facility's operating 
record, conducting the field inspection, and completing the inspection 
report. See 80 FR 21395. EPA did not receive any comments objecting to 
this time frame.
    EPA is finalizing the requirement without revision that owners or 
operators of legacy CCR surface impoundments must conduct the initial 
annual inspection no later than Monday, February 10, 2025, which is 
three months after the effective date of the final rule. This is 
codified in the regulatory text at Sec.  257.100(f)(3)(iv).
v. Initial Inflow Design Flood Control System Plan for Legacy CCR 
Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments must prepare the inflow design flood control system plan 
nine months after the effective date of the final rule. Owners or 
operators of all CCR surface impoundments are required to design, 
construct, operate, and maintain hydraulic and hydrologic capacity to 
adequately manage flow both into and from a CCR surface impoundment 
during and after the peak discharge resulting from the inflow design 
flood, which is based on the Hazard Potential Classification of the CCR 
surface impoundment (Sec.  257.82(a)). The regulation also requires the 
preparation of an initial inflow design flood control system plan 
(Sec.  257.82(c)). See also 80 FR 21390-21392.
    EPA did not receive any comments about this requirement. However, 
overall, most commenters believed that compliance deadlines should not 
be accelerated to be shorter than required for active units. Commenters 
also believed that substantial data collection efforts might be 
required resulting in situations where it is not feasible to meet the 
proposed deadline. For example, there is an ongoing shortage of 
contractors (e.g., consultants, drillers, laboratories) to complete 
this work. EPA considered these comments and extended the deadline to 
18 months in consideration of third-party availability and in order to 
match the 2015 CCR Rule.
    EPA is finalizing the requirement that owners or operators of 
legacy CCR surface impoundments prepare the inflow design flood control 
system plan no later than Friday, May 8, 2026, which is 18 months after 
the effective date of the final rule. This is codified in the 
regulatory text at Sec.  257.100(f)(3)(v).
f. Groundwater Monitoring and Corrective Action Criteria for Legacy CCR 
Surface Impoundments
    EPA proposed to require legacy CCR surface impoundments to comply 
with the existing groundwater monitoring

[[Page 39017]]

and corrective action criteria in 40 CFR 257.90 through 257.98, with 
one revision, to require sampling and analysis of constituents listed 
in Appendix IV at the same time as those listed in Appendix III. As 
explained in the proposed rule at 88 FR 32003, Sec. Sec.  257.90 
through 257.95 require owners or operators of a CCR unit to install a 
system of monitoring wells, specify procedures for sampling these 
wells, and set forth methods for analyzing the groundwater data 
collected to detect hazardous constituents (e.g., toxic metals) and 
other monitoring parameters (e.g., pH, total dissolved solids) released 
from the units. If the groundwater monitoring required in Sec.  257.95, 
demonstrates an exceedance of the groundwater protection standards for 
constituents identified in Appendix IV of part 257, corrective action 
is required as laid out in Sec. Sec.  257.96 through 257.98. These 
requirements apply throughout the active life and post-closure care 
period of the CCR unit.
    Several commenters expressed support for requiring legacy CCR 
surface impoundments to comply with these groundwater monitoring and 
corrective action requirements, stating CCR units can and have caused 
groundwater contamination. Some commenters suggested additional 
requirements be added to those in Sec. Sec.  257.90 through 257.98, 
including a mandate to test groundwater quality outside the boundary of 
the facility and make those results public; a report documenting the 
unit's proximity to the closest surface water body and nearest private 
and public groundwater wells; a deadline for the completion of the 
selection of remedy required by Sec.  257.97; and a prohibition against 
using intrawell groundwater data comparisons at legacy CCR surface 
impoundments. Other commenters stated that applying the existing 
corrective action requirements to historic sites, such as legacy CCR 
surface impoundments, is not appropriate and suggested that instead EPA 
incorporate site-specific risk-based corrective action into the CCR 
regulations.
    EPA further proposed two deadlines for the groundwater monitoring 
requirements, as opposed to the single deadline in the 2015 CCR Rule. 
EPA received numerous comments on EPA's proposal to split the single 
deadline for groundwater monitoring requirements contained within the 
2015 CCR Rule (24 months from the effective date of the final 2015 
rule) into two separate deadlines (six months from the effective date 
of the final rule for the installation of the groundwater monitoring 
network and development of the groundwater sampling and analysis plan 
and 24 months from the effective date of the final rule for the 
initiation of the combined detection and assessment monitoring). A few 
commenters expressed support of the two separate deadlines for 
groundwater monitoring requirements, stating it increased 
accountability and ensured owners or operators were not unnecessarily 
delaying the installation of the groundwater monitoring system. 
However, overall, commenters stated that the groundwater monitoring 
requirements should have a single deadline as the separate deadlines 
made compliance with the rule infeasible. Several commenters said the 
proposed split deadlines eliminated the flexibility necessary for 
compliance that was contained within the 2015 CCR Rule's single 
deadline. Those commenters went on to say the single deadline allowed 
facilities to accommodate for delays associated with factors outside 
their control, such as third-party availability, weather, and required 
permits or approvals, by making schedule adjustments necessary to 
achieve compliance (e.g., expedite the development of the sampling plan 
in the case of delays with the well installation). Other commenters 
said the proposed two deadlines were unnecessarily prescriptive. One 
commenter pointed out that the proposed rule contained no deliverables 
to verify compliance for the installation of wells or the development 
of the sampling and analysis plan.
    As explained in the proposed rule, the existing groundwater 
monitoring and corrective action requirements are essentially the same 
requirements that have been applied to both hazardous waste and 
municipal solid waste disposal units for decades, and with the one 
exception discussed below, there is nothing about legacy CCR surface 
impoundments that makes them distinct enough to warrant separate 
requirements from those for other CCR surface impoundments. No 
commenter provided any factual basis for treating legacy impoundments 
differently than all the other units that currently comply with the 
same groundwater monitoring requirements, including other inactive CCR 
surface impoundments. For those commenters requesting that EPA adopt 
``risk-based corrective action'' into the requirements, EPA notes that 
the commenters have provided no further explanation of what 
requirements in the existing regulations they wanted EPA to revise, 
what the revisions should accomplish, or why they are necessary or 
appropriate. As a general matter EPA considers that the corrective 
action regulations in Sec. Sec.  257.95 through 257.98 do currently 
require facilities to tailor remedies to address the risks to human 
health and the environment, based on the conditions at the site. It is 
unclear what more the commenters are seeking. Accordingly, EPA is 
finalizing the proposal that legacy CCR surface impoundments comply 
with the existing groundwater monitoring and corrective action 
requirements with one modification, combined detection and assessment 
monitoring.
    However, EPA agrees that having a single deadline for groundwater 
monitoring requirements as opposed to two deadlines allows flexibility 
to complete tasks, such as installing groundwater wells and collecting 
independent samples, which is necessary for compliance with a 
nationwide rule. The activities involved in achieving compliance with 
the groundwater monitoring requirements (i.e., drilling wells, 
collecting samples, receiving lab results) are more susceptible to 
factors outside a facility's control, such as extreme weather events, 
shortages of qualified contractors, and permitting or approval delays, 
and therefore, warrant greater flexibility. Additionally, activities 
can be restricted dependent on the time of year and the location of the 
facility (e.g., due to seasonality, protected species, clearing 
restrictions). Because the groundwater monitoring requirements build 
upon each other, EPA must ensure that facilities nationwide are 
reasonably able to achieve regulatory compliance by the deadline. 
Utilizing a single deadline for the groundwater monitoring requirements 
allows facilities to make reasonable accommodations for regional 
factors in a way the proposed deadlines do not, while still maintaining 
the same level of protection for human health and the environment. 
Furthermore, EPA agrees that the proposed rule does not have a clear 
mechanism for facilities to prove compliance or for interested parties 
to verify compliance with the separate deadlines for the installation 
of the groundwater monitoring network and the development of the 
groundwater sampling and analysis plan. Finally, based on the 
information provided by commenters, specifically the information 
regarding the current labor shortages and backlogs experienced by third 
parties necessary to accomplish tasks involved in complying with the 
groundwater monitoring requirements (e.g., drillers for well 
installation, laboratories for sample analysis), time needed to obtain

[[Page 39018]]

necessary approvals (e.g., State permits to drill water wells or clear 
vegetation), and to accommodate for seasonality, EPA has calculated six 
months as the appropriate extension of the 2015 CCR Rule groundwater 
monitoring system deadlines. Therefore, EPA is finalizing a single 
deadline of no later than 30 months after the effective date of this 
final rule for the groundwater monitoring requirements found at 
Sec. Sec.  257.90 through 257.95.
i. Design and Installation of the Groundwater Monitoring System for 
Legacy CCR Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments install the groundwater monitoring system as required by 
Sec.  257.91 no later than six months from the effective date of this 
final rule. EPA further proposed that existing monitoring wells can be 
used as a part of the legacy CCR surface impoundment groundwater 
monitoring systems provided the wells meet Sec.  257.91. As explained 
in the proposed rule, based on the amount of time most facilities 
needed to complete or to collect baseline sampling, EPA calculated that 
facilities would be able to install the necessary monitoring wells 
within a single year.
    As mentioned above, some commenters supported the expedited 
deadlines. However, most commenters stated the proposed deadline of six 
months from the effective date of the final rule for the design and 
installation of the groundwater monitoring network was infeasible and 
should be extended to no less than 24 months from the effective date to 
align with the 2015 rule deadline. As explained above, many of these 
commenters expressed the need for a single deadline for groundwater 
monitoring requirements. Furthermore, as described in Unit III.B.2.a.ii 
of this preamble, these commenters cited seasonality restrictions, the 
nationwide labor shortages, limited qualified contractor availability, 
the need for State approvals and permits, and the number of facilities 
competing for limited resources as reasons for why the proposed 
expedited deadline is infeasible. A few commenters noted that in recent 
decisions on Part A demonstrations, EPA cited deficiencies in the 
groundwater monitoring network as a basis for non-compliance. These 
commenters went on to state that the proposed deadline does not 
facilitate the establishment of a monitoring system that would meet the 
standards laid out in the CCR rule or the recent proposed decisions and 
thus, the proposed deadline creates de facto non-compliance. One of 
these commenters elaborated by saying that the deadline does not allow 
facilities to acquire the permits that may be required to drill wells 
and precludes the observation of groundwater levels over time, which is 
needed to properly characterize groundwater flow. Other commenters 
stated meeting the proposed compliance deadline would prevent a 
facility from conducting proper site characterization, which is needed 
to inform well placement and depth and provide professional engineers 
sufficient information to certify the groundwater monitoring system. 
Lastly, commenters stated that contrary to EPA's assertion in the 
proposed rule that expediting the installation of the groundwater 
monitoring network is protective of human health and the environment, 
to meet the proposed deadline, facilities would likely be forced to 
design groundwater monitoring systems based on inadequate data 
resulting in unreliable groundwater monitoring data. Commenters 
provided estimates of time needed to comply with the design and 
installation of the groundwater monitoring system requirements ranging 
from 12 to 36 months.
    As stated in Unit III.B.2.a.ii of this preamble, in response to 
comments EPA reevaluated the compliance deadline for the design and 
installation of the groundwater monitoring network and found the 
information provided regarding the general infeasibility of the 
proposed deadline compelling. Specifically, EPA agrees that more time 
is needed to account for limited third-party availability (e.g., 
contractor shortages and laboratory backlogs), seasonality and extreme 
weather events, procuring a contractor, complying with overlapping 
regulatory requirements, and coordinating with outside parties. EPA 
acknowledges the importance of proper site characterization as the 
foundation for designing a groundwater monitoring system and is 
convinced that although there may be some legacy CCR surface 
impoundments that have sufficient historical documentation for site 
characterization, many of these units may need to conduct more 
extensive site reconnaissance and field work to obtain the necessary 
information. Lastly, EPA recognizes that groundwater monitoring systems 
designed using inadequate data would be unable to properly monitor 
groundwater quality coming from the unit and therefore would not be 
protective of human health and the environment. Therefore, because EPA 
is convinced by information from the commenters that facilities would 
be unable to conduct all the steps necessary to design and install a 
groundwater monitoring system capable of meeting the standards in Sec.  
257.91 by the proposed deadline, EPA has extended the deadline.
    As stated in Unit III.B.2.f, based on information provided by 
commenters, EPA concluded that a single deadline should be used for the 
groundwater monitoring requirements. In the proposed rule, the latest 
proposed deadline for groundwater monitoring requirements was the 
deadline of 24 months from the effective date of this final rule for 
the initiation of the combined detection and assessment monitoring and 
the collection of the eight baseline samples. Based on information 
provided in response to comments on the proposed rule and as explained 
in Unit III.B.2.f, EPA calculated six months as the appropriate 
extension of the groundwater monitoring system deadlines. Therefore, 
EPA is finalizing a deadline for the completion of the design and 
installation of the groundwater monitoring system of no later than 
Monday, May 10, 2027, which is 30 months from the effective date of 
this final rule. This is codified in the regulatory text at Sec.  
257.100(f)(4)(i).
    To complete the installation of the groundwater monitoring system, 
the owner or operator of a legacy CCR surface impoundment must ensure 
the monitoring system consists of sufficient number of wells both 
upgradient and downgradient of the CCR unit, installed at appropriate 
locations and depths, to yield groundwater samples from the uppermost 
aquifer that accurately represent the quality of background groundwater 
and groundwater passing the downgradient waste boundary of the CCR 
unit, monitoring all potential contaminant pathways. 40 CFR 
257.91(a)(1) through (2). Because hydrogeologic conditions vary so 
widely from one site to another, the regulations do not prescribe the 
exact number, location, and depth of monitoring wells needed to achieve 
the general performance standard. Rather the regulation requires 
installation of a minimum of one upgradient and three downgradient 
wells, as well as any additional monitoring wells necessary to achieve 
the general performance standard of accurately representing the quality 
of the background groundwater and the groundwater passing. See, 80 FR 
21399. The number and placement of the monitoring wells is critical to 
proper characterization of the groundwater. Thus, the specific number, 
spacing, and depth of the monitoring wells must be determined based on 
site-specific

[[Page 39019]]

information, including but not limited to the thorough characterization 
of aquifer thickness, groundwater flow rate, groundwater flow direction 
throughout seasonal and temporal fluctuations, the unit's geological 
setting, and the unit's hydrogeological setting.
    The monitoring wells must be cased, constructed, operated, and 
maintained in a way that preserves the integrity of the monitoring well 
borehole, screened interval and other components so as to ensure the 
well performs to the design specifications throughout the life of the 
monitoring system. EPA expects owners or operators to ensure the 
groundwater monitoring wells are adequately protected from activities 
that may damage the wells or otherwise adversely impact their 
performance, such as accidental damage caused by livestock, vehicles, 
machinery, or other activities near the unit.
    The owner or operator of the unit must ensure that the design, 
installation, development, and decommissioning of any aspect of the 
groundwater monitoring system is thoroughly documented and included in 
the operating record. Furthermore, the owner or operator must obtain a 
P.E. certification or approval from the Participating State Director or 
EPA stating the groundwater monitoring system meets the standards set 
out in Sec.  257.91.
ii. Development of the Groundwater Sampling and Analysis Program for 
Legacy CCR Surface Impoundments
    EPA proposed to require owners or operators of legacy CCR surface 
impoundments to comply with the existing groundwater sampling and 
analysis program requirements for CCR surface impoundments, including 
the selection of the statistical procedures that will be used for 
evaluating groundwater monitoring data. 40 CFR 257.93. EPA proposed a 
deadline of no later than six months after the effective date of the 
final rule for owners or operators to comply with this requirement.
    One commenter suggested EPA prohibit use of intrawell groundwater 
data comparisons for legacy CCR surface impoundments. This commenter 
stated that intrawell comparisons are only appropriate when the 
background samples are collected before CCR was placed in the unit and 
therefore, since these units are likely already leaking, they would be 
ineligible for intrawell data comparisons. As stated in Unit III.B.2.f, 
the existing groundwater monitoring and corrective action requirements 
are essentially the same requirements that have been applied to both 
hazardous waste and municipal solid waste disposal units for decades, 
and with the one exception discussed below, there is nothing about 
legacy CCR surface impoundments that makes them distinct enough to 
warrant separate or additional requirements. Furthermore, while EPA 
expects legacy CCR surface impoundments to largely be unlined and 
potentially leaking, the commenter did not provide any evidence that 
would support creating a prohibition against intrawell data 
comparisons. Therefore, EPA did not adopt a prohibition on intrawell 
data comparisons at legacy CCR surface impoundments. However, EPA 
acknowledges that since the 2015 CCR Rule went into effect, intrawell 
groundwater data comparisons have been misused to a large degree. No 
commenters raised concern about requiring legacy CCR surface 
impoundments to comply with the existing requirements in Sec.  257.93. 
EPA is therefore finalizing this provision without revision. This is 
codified in the regulatory text at Sec.  257.100(f)(4)(ii).
    However, EPA received several comments on the proposed deadline for 
the development of the groundwater sampling and analysis plan. As 
mentioned in Unit III.B.2.a.ii, some commenters supported the expedited 
deadline. However, several other commenters pointed out that the 
sampling and analysis plan cannot be completed prior to the collection 
of the baseline samples, which had a proposed deadline of 24 months 
from the effective date. Many of these commenters went on to state that 
the proposed expedited deadline for the development of the sampling and 
analysis plan could result in too frequent sampling leading to non-
independent, autocorrelated baseline samples for a large number of 
facilities, undermining the required statistical analysis. A few 
commenters further stated that EPA published decisions on Part A and 
Part B demonstrations citing lack of statistical independence in 
sampling as a basis for non-compliance, and failure for EPA to extend 
the deadline for the sampling and analysis plan to allow adequate time 
for facilities nationwide to gather independent samples would create de 
facto non-compliance.\59\ Commenters also said that the proposed 
deadlines do not account for the backlogs already experienced due to 
the existing CCR units using the small number of laboratories qualified 
to conduct the specialized analyses required by the rule, coupled with 
the national labor shortages. The commenters predicted the backlogs 
with laboratories will only increase with the regulation of legacy CCR 
surface impoundments and CCRMU, making the proposed deadlines even more 
infeasible. Finally, as mentioned in Unit III.B.2.f, commenters 
emphasized the need for one deadline for all groundwater monitoring 
requirements.
---------------------------------------------------------------------------

    \59\ On January 25, 2023, EPA proposed determinations on six 
Part B applications for alternate liner demonstrations (``Part B''). 
All six proposals are proposed denials. The CCR Part B Final Rule 
(85 FR 72506, November 12, 2020), allowed a limited number of 
facilities to demonstrate to EPA or a Participating State Director 
that, based on groundwater data and the design of a particular 
surface impoundment, the unit has and will continue to ensure there 
is no reasonable probability of adverse effects to human health and 
the environment.
---------------------------------------------------------------------------

    EPA agrees that a sampling and analysis plan cannot reasonably be 
completed before the collection of baseline samples. EPA also 
acknowledges the adverse impact of too frequent sampling on the 
validity of statistical analysis and the need to account for seasonal 
variability in groundwater flow, groundwater levels, and constituent 
concentrations. EPA further acknowledges that providing insufficient 
time for the collection of baseline samples or the development of the 
sampling and analysis plan would likely result in ineffective 
groundwater monitoring programs that may fail to alert facilities to 
groundwater contamination coming from CCR units. As explained in Unit 
III.B.2.a.ii and Unit III.B.2.f respectively, EPA recognizes the need 
for more time to accommodate third-party availability and a single 
deadline for the groundwater monitoring requirements. As stated in Unit 
III.B.2.f.i, for the reasons laid out above, EPA is finalizing a single 
deadline for the groundwater monitoring requirements of no later than 
Monday, May 10, 2027, which is 30 months from the effective date of 
this final rule.
    The owner or operator must develop the groundwater sampling and 
analysis program that satisfies the requirements in Sec.  257.93 and 
includes a list of monitoring wells to be sampled (i.e., the monitoring 
network), the schedule for sampling, sampling procedures and 
techniques, sample preservation and shipping protocols, analytical 
procedures including an appropriate statistical method for analysis, 
and quality assurance and quality control methods. The sampling and 
analysis plan must include all analytes listed in Appendix III and 
Appendix IV. Recommendations and information on how to comply with many 
of the

[[Page 39020]]

requirements for the groundwater sampling and analysis program (e.g., 
analytical procedures, QA/QC controls, sampling protocol) can be found 
in the following EPA guidance documents (e.g., RCRA Groundwater 
Monitoring: Draft Technical Guidance, 1992, EPA/530/R-93/001; Low-Flow 
(Minimal Drawdown) Ground-Water Sampling Procedures, 1996, EPA/540/S-
95/504).
iii. Detection Monitoring Program and Assessment Monitoring Program 
Combined
    EPA proposed to require sampling and analysis of constituents 
listed in Appendix IV at the same time as those listed in Appendix III. 
The proposed rule explained that this would expedite groundwater 
monitoring and initiation of corrective action by at least six months 
at sites where units have potentially been leaking for a time, as is 
likely the case at unlined legacy CCR surface impoundments. The 
proposed rule further explained that expediting Appendix IV constituent 
detection and any resulting corrective action is necessary for the 
protection of human health and the environment. EPA proposed no other 
revisions to the existing groundwater monitoring requirements in 
Sec. Sec.  257.90 through 257.95.
    EPA received few comments on its proposal to combine detection and 
assessment monitoring. One commenter pointed out the increased demand 
on laboratory services, facility staff and/or contractors, and P.E.s 
that would result from having all legacy CCR surface impoundments 
comply with both monitoring programs simultaneously. Another commenter 
stated that by combining detection and assessment monitoring and 
assuming groundwater contamination, EPA has rendered detection 
monitoring superfluous. Further, the commenter asserted that skipping 
detection monitoring entirely would lose critical data regarding 
whether there are statistically significant increases (SSI) in 
groundwater constituents specifically due to the unit being monitored. 
Another commenter said that the justification in proposed rule 
regarding phased groundwater monitoring being ``best suited to 
situations where there is little likelihood of pre-existing 
contamination'' conflicts with EPA's position in the 2015 CCR Rule. 
According to the commenter, in the 2015 CCR Rule, the Agency was aware 
many CCR surface impoundments were decades old and potentially leaking; 
yet EPA still adopted a phased approach with detection monitoring to 
monitor indicators of potential groundwater contamination and 
assessment monitoring to determine if releases of CCR constituents of 
concern did occur.
    As explained in the proposed rule, the phased approach in the 2015 
CCR Rule is best suited to situations where there is little likelihood 
of pre-existing contamination, such as at a new facility or unit. As 
EPA explained in 2015, detection monitoring was designed to provide an 
early warning that a unit might be contaminating the aquifer, by first 
monitoring for constituents that would rapidly move through the 
subsurface and thus provide early detection of a potential problem 
before significant releases of constituents of concern (i.e., those in 
Appendix IV) had occurred. See, 80 FR 21397. At a site without an old, 
unlined impoundment, or other evidence of pre-existing contamination, a 
graduated response to increasing evidence of leakage and potential 
contamination is easily justified, as it both allows facilities ample 
time to investigate the source of contamination as well as the 
environmental fate and transport characteristics of CCR constituents in 
groundwater, while still protecting human health and the environment. 
In essence, this approach rests on a presumption that the unit is not 
already leaking. At new sites, for example, there is no reason to 
expect that groundwater will have been contaminated above regulatory 
levels of concern prior to detection by the groundwater monitoring 
system.
    But that presumption is largely inapposite for a universe 
consisting exclusively of historic unlined units, many of which have 
operated for decades. And at sites where leakage (and therefore, likely 
groundwater contamination) has been occurring for a sustained period, 
the need to protect human health and environment warrants the quick 
detection of constituents of concern and initiation of any necessary 
corrective action. Unlike this rule, the 2015 CCR Rule applied both to 
new facilities, which would be expected to have little likelihood of 
pre-existing contamination, and to currently operating facilities. Over 
the long term, EPA expected that there would eventually be a greater 
percentage of new units than existing units as the older units reached 
capacity and closed. In addition, as discussed in the proposal at 88 FR 
32010 and in Unit III.A.2 of this preamble, it is clear from the data 
posted on facilities' websites that EPA significantly underestimated 
the number of unlined units (both impoundments and landfills), and 
consequently, significantly underestimated the number of leaking units 
and the extent of contamination at these sites. In light of these 
considerations, EPA's decision in 2015 to adopt phased monitoring was 
reasonable.
    By contrast, there is good reason to believe that many legacy CCR 
surface impoundments are currently contaminating groundwater, based on 
the record from the 2015 CCR Rule, the results of EPA's recent 
modeling, and the large number of presently regulated CCR surface 
impoundments that have been found to be leaking, despite frequently 
inadequate groundwater monitoring networks. In sum, the totality of 
this record demonstrates that it is highly likely that the installation 
of groundwater monitoring at legacy impoundments will identify the 
presence of plumes of contaminated groundwater that have persisted or 
even expanded over many prior years despite a previous absence of 
groundwater data.
    As a practical matter, EPA expects combining Appendix III and 
Appendix IV constituents into a unified sampling and analysis plan and 
approach will likely have only minor effects on schedules, as this 
change will not require additional field mobilizations or sampling 
events and will only require collection of a slightly larger number of 
sample containers at each monitoring well to allow for analysis for 
both Appendix III and IV constituents. As such, no additional shipments 
of samples to the analytical laboratory will be required. However, EPA 
acknowledges that combining Appendix III and Appendix IV constituents 
into a unified sampling and analysis plan may increase the total 
throughput burden on analytical laboratories and related services. 
Similarly, while combined monitoring may require additional evaluation 
(e.g., concentration and trend analysis of data concerning both 
Appendix III and Appendix IV constituents), this incremental increase 
is unlikely to significantly increase the overall reporting level of 
effort, as the number of reports will be essentially unchanged.
    Nevertheless, as discussed in Units III.B.2.a.ii and III.B.2.f of 
this preamble, EPA acknowledges the commenters' concerns regarding 
existing and projected labor shortages, backlogs, and third-party 
availability, and agrees this has the potential to affect facilities' 
ability to comply with the proposed deadlines for groundwater 
monitoring requirements. EPA is therefore extending the deadline, as 
well as building in flexibility for facilities to accommodate for 
delays, by finalizing a single deadline for groundwater

[[Page 39021]]

monitoring requirements in lieu of the proposed split deadlines.
    However, EPA disagrees that combining detection and assessment 
monitoring will render detection monitoring redundant, and that 
critical data would be lost, by sampling for Appendix IV constituents 
at the same time as Appendix III constituents (i.e., by collecting more 
information). The commenters provided no further explanation of what 
information they thought would be lost, but under the combined 
monitoring, the facility would collect the same information on Appendix 
III constituents that is collected under the detection monitoring in 
Sec.  257.94. Given that under the existing assessment monitoring 
provisions, facilities must simultaneously analyze samples for all 
parameters in Appendix III and for any Appendix IV constituent detected 
in the initial sampling, it is not apparent why the commenter believes 
that requiring simultaneous monitoring more broadly is appreciably 
different. 40 CFR 257.95(d)(1).
    As stated in the previous paragraph, concurrent monitoring for 
Appendix III and Appendix IV constituents provides considerably more 
information and enables a more complete understanding of the 
geochemical nature, fate, and transport of any detected releases. 
Additionally, simultaneously collecting samples for Appendix III and 
Appendix IV constituents will still provide the basis for determining 
SSIs, should they exist, so no information will be lost. Contrary to 
the commenter's concern, additional information will be gained in an 
expedited manner (e.g., the potential spatial and temporal correlation 
of Appendix III SSIs with exceedances of statistically significant 
levels (SSLs) for Appendix IV constituents). Furthermore, EPA disagrees 
that its explanation that phased groundwater monitoring is ``best 
suited to situations where there is little likelihood of pre-existing 
contamination'' fundamentally conflicts with EPA's decision to adopt 
phased monitoring in the 2015 CCR Rule. Unlike this final rule, the 
2015 CCR Rule applied to both new facilities, which would be expected 
to have little likelihood of pre-existing contamination, and to 
existing facilities. Over the long-term, EPA expected that there would 
eventually be a greater percentage of new units than existing units as 
the older units reached capacity and closed. In addition, as discussed 
in the proposal at 88 FR 32010 and in Unit III.A.2 of this preamble, it 
is clear from the data posted on facilities' websites that in 2015 EPA 
significantly underestimated the number of unlined units (both 
impoundments and landfills), and consequently, significantly 
underestimated the number of leaking units and the extent of 
contamination at these sites.
    If an alternate source is causing an exceedance of an Appendix III 
constituent, it may also be the source of any SSL detected for any 
Appendix IV constituents; in such a case, a facility may simply prepare 
a single ASD that covers constituents from both appendices. The sole 
difference between phased monitoring and combined monitoring is if the 
alternate source is only responsible for the Appendix III constituent, 
but the unit actually is releasing one or more Appendix IV 
constituents. In such a case, under a phased approach detection of the 
Appendix IV constituent can be delayed or even remain undetected, 
because the facility would not trigger assessment monitoring absent an 
SSI from another Appendix III constituent. In such situations, combined 
monitoring can make the monitoring program more accurate; it is unclear 
why the commenter believes this is inappropriate.
    To avoid unnecessary and potentially inappropriate delays, ASDs 
should only be considered in cases where there is a strong technical 
case for an alternate source, and technically weak or equivocal ASDs 
should be rejected as soon as is appropriate to minimize delays in 
corrective action implementation. Given the age of most inactive CCR 
facilities, the potential for plumes of groundwater contamination 
extending for significant distances downgradient of the unit boundaries 
where exceedances are first determined should be anticipated. 
Additional lateral and vertical delineation of groundwater exceedances 
should be conducted in conjunction with corrective action as needed.
    Ultimately, the combined monitoring expedites the initiation of 
assessment monitoring which in turn, allows for more expeditious 
identification of statistically relevant exceedances of Appendix IV 
constituents. This will in turn expedite ASD development or corrective 
action, depending on the circumstances.
    The phased approach in the 2015 CCR Rule provides for a graduated 
response to groundwater contamination as the evidence of contamination 
increases over time. This approach allows facilities ample time to 
investigate the source of contamination as well as the transport 
characteristics of CCR constituents in groundwater while, usually being 
protective of human health and the environment. However, at sites where 
there is a strong likelihood that groundwater contamination has been 
occurring for a sustained period, the advantages provided by a 
protracted graduated response are outweighed by disadvantages of 
persistent or even increasing contamination that continues to move 
downgradient. At these sites, the need to protect human health and the 
environment necessitates the quick detection of the constituents of 
concern in Appendix IV to expedite any necessary corrective action. 
See, USWAG 901 F.3d at 427-30. In this case, as highlighted in Unit 
III.A, the record provides strong reason to conclude that many legacy 
CCR surface impoundments are contaminating groundwater, given the large 
number of currently regulated CCR surface impoundments that have been 
found to be leaking.
    Therefore, EPA is finalizing this requirement as proposed to be 
completed no later than Monday, May 10, 2027, which is 30 months after 
the effective date of this final rule. This is codified in the 
regulatory text at Sec.  257.100(f)(4)(iii)(B) and (C).
iv. Detection Monitoring Program and Assessment Monitoring Program--
Deadline for Collection and Analyses of Eight Independent Samples for 
Legacy CCR Surface Impoundments
    EPA proposed that no later than 24 months after the effective date 
of the final rule, owners or operators of legacy CCR surface 
impoundments initiate the detection monitoring program by completing 
sampling and analysis of a minimum of eight independent samples for 
each background and downgradient well, as required by Sec.  257.94(b). 
The proposed rule explained that within 90 days after initiation of the 
detection monitoring program, owners or operators must identify any 
SSIs over background levels for the constituents listed in Appendix 
III, as required by Sec.  257.94. To expedite the time to initiate any 
required corrective action, EPA also proposed that by this same 
deadline owners or operators initiate the assessment monitoring program 
by establishing groundwater protection standards and staring to 
evaluate the groundwater monitoring data for an SSL over GWPS for the 
constituents listed in Appendix IV as required by Sec.  257.95.
    No commenters raised concern about requiring legacy impoundments to 
comply with the existing requirements in Sec.  257.94(b). Therefore, 
EPA is finalizing this requirement as proposed. This is codified in the 
regulatory text at Sec.  257.100(f)(4)(iii)(A).

[[Page 39022]]

    However, EPA received several comments on the proposed deadline for 
the collection of the eight baseline samples. As mentioned in Unit 
III.B.2.a.ii, some commenters supported the expedited deadline. 
However, several other commenters requested that the groundwater 
monitoring requirement deadlines be combined into a single deadline 
that provided at least as much time to come into compliance as was 
provided in the 2015 CCR Rule deadlines (i.e., 24 months after the 
effective date of the final rule). As stated in Unit III.B.2.f, based 
on information provided by commenters, EPA concluded that a single 
deadline should be used for the groundwater monitoring requirements. In 
the proposed rule, the latest proposed deadline for groundwater 
monitoring requirements was the deadline of 24 months from the 
effective date of this final rule for the initiation of the combined 
detection and assessment monitoring and the collection of the eight 
baseline samples. Based on information provided in response to comments 
on the proposed rule and as explained in Units III.B.2.a.ii and 
III.B.2.f, EPA calculated six months as the appropriate extension of 
the groundwater monitoring system deadlines. Therefore, EPA is 
finalizing a deadline for the completion of sampling and analysis of a 
minimum of eight independent samples for each background and 
downgradient well of no later than Monday, May 10, 2027, which is 30 
months from the effective date of this final rule.
v. Annual Groundwater Monitoring and Corrective Action Reports for 
Legacy CCR Surface Impoundments
    EPA proposed to apply the existing requirements in Sec.  257.90(e) 
to legacy CCR surface impoundments and that owners or operators of 
legacy CCR surface impoundments comply no later than January 31 of the 
year following the calendar year after a groundwater monitoring system 
has been established (and annually thereafter).
    One commenter suggested that the initial groundwater monitoring and 
corrective action report be due no later than January 31 of the year 
following the collection of the eight baseline samples and the first 
semi-annual sampling event in order to allow facilities to provide all 
the documentation required by Sec.  257.90(e). EPA disagrees that the 
information required by Sec.  257.90(e) would not be available to a 
facility upon completion of the groundwater monitoring system, as the 
annual report serves as an update on the activities related to the 
groundwater monitoring program, including the installation of 
groundwater monitoring wells. Additionally, when specific actions are 
not required by the CCR regulations (e.g., a facility has not triggered 
corrective action), facilities are not penalized for not having any 
activities related to that action to discuss in the groundwater 
monitoring and corrective action annual report (e.g., not describing 
progress in selecting a remedy when not in corrective action).
    EPA is finalizing the requirement for owners or operators of legacy 
CCR surface impoundments to comply with the requirements in Sec.  
257.90(e) which mandate the preparation of an annual groundwater 
monitoring and corrective action report no later than January 31, 2027, 
and annually thereafter. This is codified in the regulatory text at 
Sec.  257.100(f)(4)(iv).
    The report documents the activities associated with the groundwater 
monitoring program and progress of any corrective action over the past 
year and must contain specific information identified in the 
regulations, including but not limited to maps; aerial images or 
diagrams showing the CCR unit and all upgradient (background) and 
downgradient wells; identification of any monitoring wells installed or 
decommissioned in the previous year; monitoring data collected under 
Sec. Sec.  257.90 through 257.98; and a narrative discussion of any 
transition between monitoring programs (i.e., detection and assessment 
monitoring). Annual reporting should ensure that groundwater level data 
collected over the reporting period is tabulated, presented, and 
analyzed to determine groundwater levels relative to any residual CCR 
left in place as well as to confirm or determine groundwater flow 
directions.
    Upgradient and downgradient well locations and depths should be 
validated annually with respect to measured and mapped flow directions. 
Groundwater quality sampling data should be included in appendices and 
summarized and tabulated in the annual reports. If appropriate, 
exceedances (SSIs and SSLs) of Appendix III and IV constituents should 
be tabulated and highlighted. As mentioned in some comments, annual 
reports should identify the nearest downgradient surface water bodies 
as well as groundwater supply wells in the vicinity of the unit.
    If the groundwater monitoring required in Sec.  257.95, 
demonstrates an exceedance of the groundwater protection standards for 
constituents identified in Appendix IV of part 257, corrective action 
as laid out in Sec. Sec.  257.96 through 257.98, should be initiated as 
soon as possible. It is critical that annual corrective action and 
monitoring reports provide the basis for selection and documentation of 
corrective actions as early as possible well as graduated data to 
document initiation of corrective action activities and graduated and 
ongoing steps and associated data collected over the course of each 
year to document remedial performance, modifications, and other changes 
or improvements.
    In addition to documenting compliance, the annual report must be 
posted to the unit's public CCR website which allows the public to 
review the groundwater monitoring results. Therefore, it is critical 
that the annual reports contain the basic data that informs the 
positions and status reported in those documents, including but not 
limited to boring logs, monitoring well installation diagrams, water 
level data, field sampling data sheets for groundwater sample 
collection, laboratory analytical data including QA/QC data, data 
validation, and others. In summary, the annual groundwater monitoring 
and corrective action reports should not only contain the information 
required by the regulations but should be organized in such a way that: 
(1) Compliance with the CCR regulations is evident; (2) Data supporting 
compliance conclusions are easily located within the document; and (3) 
The public is readily able to review the groundwater monitoring data 
and related information. Lastly, the name of the document on the public 
CCR website should be such that it is clear what the file is and 
readily printed and downloaded by the public.
vi. Corrective Action Requirements for Legacy CCR Surface Impoundments
    EPA proposed to require owners or operators of legacy CCR surface 
impoundments to comply with the existing corrective action criteria, as 
applicable in Sec. Sec.  257.96 through 257.98. The proposed rule 
explained that conducting the sampling simultaneously would expedite 
groundwater monitoring and, where necessary, initiation of corrective 
action by at least six months at sites where units have potentially 
been leaking for a long period, as is likely the case at many unlined 
legacy CCR surface impoundments. The proposed rule further explained 
that expediting Appendix IV constituent detection, assessment and any 
subsequent corrective action would protect human health and the 
environment.
    Under the existing regulations, if groundwater monitoring 
demonstrates

[[Page 39023]]

an exceedance of the groundwater protection standards for constituents 
identified in Appendix IV of part 257, corrective action is required, 
as laid out in Sec. Sec.  257.96 through 257.98. These requirements 
apply throughout the active life and any post-closure care period of 
the CCR unit.
    A commenter suggested EPA create a deadline for the completion of 
the selection of a remedy required by Sec.  257.97 of 90 days after the 
completion of the assessment of corrective measures (ACM) with the 
ability to extend the deadline up to 180 days after the completion of 
the ACM. The commenter pointed to the failure of units regulated by the 
2015 CCR Rule to select a remedy as soon as feasible after the 
completion of the ACM as required by the rule and the subsequent 
unnecessary delay in addressing contaminated groundwater. Other 
commenters stated that applying the existing groundwater monitoring and 
corrective action requirements to historic sites, such as legacy CCR 
surface impoundments, is not appropriate and suggested that instead EPA 
incorporate site-specific risk-based corrective action into the CCR 
regulations. One of these commenters further stated that the 
application of the existing CCR corrective action requirements conflict 
with EPA's decision-making frameworks in other programs such as RCRA 
and CERCLA due to lack of site-specific risk assessments to evaluate 
risk and drive corrective action decisions. This commenter suggested 
that EPA utilize site-specific, risk-based corrective action that is 
consistent with the guidance documents EPA has developed for RCRA and 
CERCLA programs.
    EPA acknowledges the widespread non-compliance with the mandate to 
complete the selection of a remedy as soon as feasible after the 
completion of the ACM. However, EPA disagrees with the commenter's 
suggested deadline. The recommended deadline could actually have the 
effect of extending the deadline for the completion of the selection of 
a remedy beyond that in 2015 CCR Rule because ``as soon as feasible'' 
in many cases would likely be before 90 days after the completion of 
the ACM. Granting owners or operators more time to select a remedy 
would be less protective of human health and the environment. Regarding 
noncompliance with the CCR regulations, EPA has been and will continue 
to take action to address the non-compliance on a myriad of issues 
including to the failure of owner or operators to select a remedy as 
soon as feasible. EPA has announced that enforcing the CCR regulations 
is part of the ongoing set of National Enforcement and Compliance 
Initiatives and expects that enforcement actions taken as part of the 
Initiative may address, where relevant and appropriate, the concern 
raised by the commenter.\60\
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    \60\ EPA Enforcement Alert, National Enforcement and Compliance 
Initiative, Protecting Communities from Coal Ash Contamination. EPA 
Document #310F23002. December 2023. https://www.epa.gov/system/files/documents/2023-12/ccr-enf-alert-2023.pdf.
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    EPA disagrees with the suggestion that the existing corrective 
action requirements, if triggered, are inappropriate at legacy CCR 
surface impoundments. As stated in Units III.B.2.a.i and III.B.2.f, the 
physical characteristics of legacy impoundments are not sufficiently 
different from currently regulated units to justify different 
requirements. For those commenters requesting that EPA adopt ``risk-
based corrective action'' into the requirements, EPA notes that the 
commenters have provided no further explanation of what requirements in 
the existing regulations they wanted EPA to revise, what the revisions 
should accomplish, or why they are necessary or appropriate. As a 
general matter EPA considers that the corrective action regulations in 
Sec. Sec.  257.95 through 257.98 do currently require facilities to 
tailor remedies to address the risks to human health and the 
environment, based on the conditions at the site. It is unclear what 
more the commenters are seeking. Furthermore, the commenter that stated 
that the existing corrective action regulations conflict with other EPA 
programs (i.e., RCRA and CERCLA) failed to fully explain how the 
existing corrective action regulations conflict with EPA-published RCRA 
or CERCLA guidance documents or how they preclude corrective action 
decisions driven by site-specific risks. Accordingly, EPA is 
finalizing, without revision, its proposal that legacy CCR surface 
impoundments comply with the existing corrective action requirements at 
Sec. Sec.  257.95 through 257.98.
    As explained in the proposed rule at 88 FR 32003, Sec. Sec.  257.90 
through 257.95 require an owner or operator of a CCR unit to install a 
system of monitoring wells, specify procedures for sampling these 
wells, and set forth methods for analyzing the groundwater data 
collected to detect hazardous constituents (e.g., toxic metals) and 
other monitoring parameters (e.g., pH, total dissolved solids) released 
from the units (i.e., all parameters listed in Appendices III and IV). 
If the groundwater monitoring required in Sec.  257.95, demonstrates an 
exceedance of the groundwater protection standards for constituents 
identified in Appendix IV of part 257, corrective action is required as 
laid out in Sec. Sec.  257.96 through 257.98. These requirements apply 
throughout the active life and post-closure care period of the CCR 
unit.
    When corrective action is required, it should be initiated as soon 
as possible. The corrective action program includes initiating an ACM 
to prevent further releases, to remediate any releases, and to restore 
affected areas to original conditions, as specified in Sec.  257.96(a). 
After the ACM has been completed, the owner or operator must select a 
remedy that meets prescribed standards, including a requirement that 
the remedy attain the groundwater protection standards. See Sec.  
257.97(a) and (b). Finally, the corrective action program requires the 
owner or operator of the CCR unit to initiate remedial activities 
within 90 days of selecting a remedy. See Sec.  257.98(a). The 
requirement to address releases under this requirement is identical to 
those requirements for any CCR unit undertaking groundwater corrective 
action with the additional requirement that implementation of 
corrective action begin during the active life of the unit.
    EPA expects that when assessing corrective measures and selecting a 
remedy, the owner or operator of the unit will consider the impact of 
the corrective measures on the water quality and safety of the nearest 
surface water bodies and the nearest private and/or public groundwater 
wells.
    With respect to completion of an ACM and remedy selection, Sec.  
257.96(a) requires an ACM be initiated within 90 days of determining an 
SSL has occurred, and then completed within another 90 days. An 
extension, not to exceed 60 days, may be warranted due to site-specific 
conditions or circumstances. This deadline to complete an ACM, 180 to 
240 days after determining an SSL, was not proposed to be changed, so 
comments suggesting changes to these provisions are outside the scope 
of the rulemaking. Additionally, the commenters provided no reason why 
corrective measures could not be assessed and compared in an ACM and a 
remedy could not be selected. Prior to closure of a CCR unit, the 
facility has been required to characterize site conditions, including 
groundwater flow conditions and geology. The facility has knowledge of 
wastestreams and water volumes it discharges to a CCR surface 
impoundment. This information can be used to develop a groundwater 
model to predict groundwater flow conditions after wastestream disposal 
ceases and closure is initiated. EPA believes this

[[Page 39024]]

would provide sufficient characterization of post-closure conditions to 
assess and compare groundwater cleanup alternatives to complete an ACM. 
The commenters have provided no reasons or explanation why this would 
not be achievable.
    Once the ACM is complete, a public meeting has been held, and 
community input has been considered, a remedy must be selected as soon 
as feasible. EPA agrees that a selected remedy may include closure by 
removal to comply with source control requirements, and that this would 
constitute commencing implementation of a remedy. However, the selected 
groundwater remediation portion of the remedy must also be implemented 
within a reasonable time, in accordance with the schedule established 
in the remedy selection report. 40 CFR 257.97(d). Implementation of the 
source control measure does not negate this requirement.
g. Closure and Post-Closure Care Criteria for Legacy CCR Surface 
Impoundments
    EPA proposed to apply all of the existing closure and post-closure 
care requirements in Sec. Sec.  257.101 through 257.104 to legacy CCR 
surface impoundments, except for the alternative closure requirements 
in Sec.  257.103(f). The proposed rule explained that based on the data 
gathered since 2015 from the currently regulated CCR unit universe, the 
Agency considered it highly unlikely that any legacy CCR surface 
impoundment has a composite liner that meets the requirements of Sec.  
257.71 and therefore EPA expected legacy CCR surface impoundments to be 
unlined as defined by Sec.  257.71(a)(3)(i). Consistent with the USWAG 
decision and the existing regulations in Sec.  257.101(a) mandating 
that all unlined (including clay-lined) impoundments must close, EPA 
proposed to require that all legacy CCR surface impoundments initiate 
closure within 12 months of the effective date of this final rule. The 
proposed rule also explained that the alternative closure provisions in 
Sec.  257.103(f) were not appropriate for legacy CCR surface 
impoundments as these units, by definition, are inactive impoundments 
at inactive facilities and could not therefore demonstrate the need to 
continue to use the disposal unit, which is a qualifying component of 
the alternative closure provisions.
    EPA received numerous comments on its proposal to apply the 
existing the closure and post-closure care requirements Sec. Sec.  
257.100 through 257.104 to legacy CCR surface impoundments. Overall, 
most commenters supported or did not contest EPA's proposal. Some of 
these commenters agreed that requiring legacy CCR surface impoundments 
to comply with the existing closure requirements is necessary for the 
long-term protection of human health and the environment. A few of 
these commenters also suggested that EPA prohibit legacy CCR surface 
impoundments from closing with CCR in place under Sec.  257.102(d).
    Many other commenters however objected to subjecting legacy 
impoundments to Sec.  257.101(a), which requires CCR surface 
impoundments constructed without a composite liner to close. These 
commenters generally argued that a national requirement to close was 
not appropriate for legacy CCR surface impoundments and that EPA should 
instead determine whether closure is warranted at each site based on a 
finding that the individual unit at the particular site poses 
unacceptable risks. These commenters largely reiterated comments 
previously made in response to the ANPRM, without addressing EPA's 
responses in the proposal. For example, some asserted that their 
particular legacy impoundments are not contaminating groundwater and do 
not pose a risk to groundwater. One claimed that the proposal was based 
on the upper bound of risk pulled from a sensitivity analysis of a 
nationwide risk assessment based on aggregated data unrepresentative of 
any given facility, and therefore could not support a finding that any 
particular site poses ``actual risks.'' This commenter also asserted 
that a nationwide risk assessment should not be used to impose a ``one-
size-fits-all'' closure requirement or universal performance standards 
for closure, because it could drive closure methods that are not 
necessary to ensure protection of human health and the environment. 
Other commenters repeated their claims that the closure of legacy CCR 
surface impoundments would itself present greater risks than leaving 
the disposal unit in its existing state. For example, one commenter 
asserted that closing legacy impoundments could raise environmental 
justice issues associated with increased traffic and (consequently) 
decreased air quality; could risk potentially destabilizing the unit 
and disturbing native species and animal habitats; and would increase 
air emissions, water consumption, and waste generation.
    These commenters asserted that a ``risk-based'' closure or 
corrective action program was better suited ``to address the unique 
nature and unknown risk of legacy CCR surface impoundments.'' For 
example, one commenter suggested that the risks associated with legacy 
CCR surface impoundments can be better managed through corrective 
action implemented under a permit program, which the commenter believed 
would make the mandate to close these units unnecessary. The commenter 
explained that although closure can be useful as source control in 
remediating contamination, as long as the exposure pathways are 
appropriately addressed through corrective action, nearby receptors 
will not be impacted by the risks, and the RCRA subtitle D 
protectiveness standard would be met without closing the impoundment. 
Similarly, another commenter argued that mandating closure for all 
legacy impoundments is inconsistent with other RCRA and CERCLA or State 
cleanup programs, which, the commenter asserts generally use site-
specific risk assessments to determine whether closure is warranted. 
The commenter suggested that instead, the final rule should rely on the 
upcoming implementation of EPA's Federal permitting rule pursuant to 
the WIIN Act and allow a regulated entity to conduct a site-specific 
risk assessment to evaluate whether the historical CCR disposal areas 
pose ``actual risks'' and allow closure and corrective actions to be 
tailored to site-specific conditions and risks.
    Other commenters raised concern that some legacy impoundments are 
now located beneath infrastructure such as pipelines or transmission 
lines that cannot be disturbed without disrupting operations, active 
CCR units, or buildings. These commenters explained that requiring 
closure of these impoundments could adversely impact grid reliability, 
business operations, or other necessary public services (e.g., military 
infrastructure) and suggested that EPA exempt these units or at least 
extend the closure time frames to allow for closure of the impoundment 
when the other unit or structure is closed or decommissioned.\61\
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    \61\ EPA also received comments suggesting that it examine the 
cumulative impact of several recently or soon-to-be finalized power 
sector and vehicle rules. EPA performed suggested sensitivity 
analysis which demonstrated 1) the cumulative impact is not expected 
to adversely impact resource adequacy, and 2) that, considering the 
power sector rules together, the cumulative effect of these rules in 
terms of reduction in coal steam electric generating capacity is 
less than the sum of each of these rules individually for 2035. The 
affected universe of units with significant mitigation 
responsibilities among the EPA rules is overlapping, not purely 
additive, as it largely reflects the same segment of the grid's 
generation portfolio. See Resource Adequacy Analysis: Vehicle Rules, 
111 EGU rule, ELG, and MATS Technical MEMO for more information. 
Also see IPM Sensitivities MEMO. The grid analysis did not include 
the proposed or final version of this rulemaking, because this CCR 
rule primarily addresses only disposal units that have not received 
CCR since before 2015, that is the disposal units are not part of 
ongoing operations at any facility, and consequently this rule is 
not expected to impact the generation of electricity. In addition, 
EPA continues to believe this final rule will not generally impact 
current utility operations, particularly due to the revisions made 
in the final rule to address commenters concerns, as discussed in 
the preamble to the final rule (e.g., extended deadlines for CCRMU 
located under critical infrastructure).

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[[Page 39025]]

    Several commenters expressed support for the proposed 12-month 
deadline to initiate closure, stating that the shorter deadlines are 
necessary to address the increased risk from legacy CCR surface 
impoundments and likelihood these units are and have been contaminating 
groundwater. Many other commenters characterized the proposed deadline 
as infeasible for the reasons mentioned in Unit III.B.2.a.ii, including 
seasonality, need to comply with overlapping regulatory requirements, 
labor shortages, and the strain on the limited resources necessary to 
achieve compliance (e.g., contractors, laboratories, P.E.s) caused by 
the number of CCR units coming into compliance at the same time. 
Commenters also stated that compliance with the closure requirements 
should not be required until after the groundwater monitoring system 
was installed and baseline samples collected so that closure could be 
informed by the groundwater monitoring data. These commenters pointed 
to recent EPA Part A and Part B decisions as evidence of the gap 
between EPA's expectations and the closure and post-closure plans 
developed using good faith efforts by owners or operators and best 
practices; these commenters further stated that the proposed deadline 
precludes the incorporation of groundwater monitoring data in 
developing closure plans and is likely a contributing factor to the gap 
between EPA's expectation and closure and post-closure care plans 
submitted by owners or operators of currently regulated units. One 
commenter also claimed that legacy CCR surface impoundments are 
potentially still being used to manage non-CCR wastestreams, and that 
EPA consequently needed to create a mechanism for facilities to seek 
extensions similar to those that had been made available under Sec.  
257.103(f). Commenters' suggestions for alternative deadlines to 
initiate closure ranged from 24 to 34 months, or at least after the 
collection of the baseline groundwater monitoring samples required by 
Sec.  257.94.
    EPA continues to believe that applying the closure and post-closure 
requirements in Sec. Sec.  257.101 through 257.104 to legacy CCR 
surface impoundments is appropriate and necessary to protect human 
health and the environment. Based on the record compiled for the 2015 
CCR Rule, EPA concluded that ``there is little difference between the 
potential risks of an active and inactive surface impoundment; both can 
leak into groundwater, and both are subject to structural failures that 
release the wastes into the environment, including catastrophic 
failures leading to massive releases that threaten both human health 
and the environment.'' 80 FR 21343. As discussed in Unit III.B of this 
preamble, the D.C. Circuit concurred, and on that basis, vacated the 
exemption for legacy CCR surface impoundments. See, USWAG at 901 F.3d 
at 434. EPA received no information during this rulemaking that would 
support a conclusion that legacy CCR surface impoundments present fewer 
risks than other inactive CCR surface impoundments. Indeed, as 
discussed in Unit III.A, more recent information continues to indicate 
that legacy CCR surface impoundments are more likely to contaminate 
groundwater and at higher levels, even in cases where the unit no 
longer presents structural stability concerns. Based on this record and 
on the specificity of the D.C. Circuit's findings in USWAG, EPA 
considers that it has limited discretion to establish requirements for 
legacy CCR surface impoundments that are significantly different than 
those currently applicable to inactive CCR surface impoundments. 
Accordingly, EPA in most cases instances has required legacy CCR 
surface impoundments to comply with the existing closure and post-
closure requirements in 40 CFR part 257, subpart D, that are currently 
applicable to inactive CCR surface impoundments. This final rule also 
adopts the provisions that were originally proposed on March 3, 2020, 
that allow a facility closing by removal to complete required 
groundwater remediation during a post-closure care period, discussed in 
Unit III.D of this preamble.
    However, in response to comments, EPA included one additional 
provision to account for the inception of Federal permitting. A key 
feature of a permit program is that, through a subsequent public 
process, a regulatory authority can adjudicate legal and factual issues 
based on the specific facts of an individual site, that would be more 
complex and challenging to resolve in a national rule. EPA has relied 
on this feature to resolve one of the more complex legal and factual 
issues raised in this rulemaking by deferring it to the subsequent 
permitting process: how to address situations where the impoundment 
contained CCR and liquids on October 19, 2015, but prior to the 
effective date of this final rule, a facility closed its legacy CCR 
surface impoundment in accordance with standards established by a 
regulatory authority that are different than the performance standards 
in Sec.  257.102, but that are likely to provide equivalent protection 
of human health and environment. Provided certain criteria are met, EPA 
is deferring the requirement for the closed unit to comply with Sec.  
257.102 until a permit authority can evaluate the adequacy of the 
previously completed closure, and determine during permitting whether 
(as well as what) additional measures are necessary to ensure that the 
closure is as protective as Sec.  257.102. The criteria EPA is 
employing are designed to ensure that the regulatory authority 
overseeing the closure applied standards that were substantially 
equivalent to the otherwise-applicable CCR rules in terms of evaluating 
and mitigating the risks. In such cases, EPA would therefore have 
reliable evidence that the risks have likely been adequately mitigated 
and therefore, these are unlikely to pose a reasonable probability of 
adverse effects pending later permitting. The final rule also includes 
procedures for the closure equivalency determination modeled on similar 
determinations made for hazardous waste interim status units under 
Sec.  270.1.
    EPA is currently transitioning from the exclusively rule-based 
program to a Federal permitting program. Although every unit in 
operation, closure, or corrective action will ultimately receive a 
permit, and EPA expects to shortly begin issuing permits, it will be 
several years before permits are issued for every unit. This means 
that, at least in the near term, most facilities will continue to 
operate under the current self-implementing regime, similar to units 
under the subtitle C hazardous waste program that initially operated 
under interim status prior to obtaining a permit. While this 
necessarily limits the degree to which this final regulation can rely 
on the permitting process, this is an example of a situation that is 
better resolved through a combination of a national rulemaking and the 
individualized decision making provided through permitting rather than 
exclusively through a national rulemaking. EPA agrees that there are

[[Page 39026]]

examples of units closed under alternative criteria that appear to be 
equally as protective as the part 257 closure requirements. If EPA were 
to require all previously closed units to document compliance with 
Sec.  257.102 immediately, several units that have likely already met 
the protectiveness standards would be swept in unnecessarily. 
Unfortunately, it is not feasible to evaluate these individual closures 
as part of this national rulemaking; these units are all subject to 
different requirements, and commenters have provided insufficient 
information on each individual unit for the Agency to conclude that 
they are in fact as protective as a closure conducted in accordance 
with Sec.  257.102. If EPA were still limited to issuing minimum 
national criteria through rulemaking, it would be reasonable to craft a 
regulation that would regulate over broadly in order to ensure that the 
final rule achieves the statutory standard at each facility subject to 
the regulation. See 42 U.S.C. 6944(a)(``no reasonable probability of 
adverse effects on health or the environment . . . at such facility''). 
As EPA explained in 2015, to establish criteria under this provision, 
EPA must demonstrate, through factual evidence available in the 
rulemaking record, that the final rule will achieve the statutory 
standard at all sites subject to the standards based exclusively on the 
final rule provisions. This means that the regulations must account for 
and be protective of all sites, including those that are highly 
vulnerable. But now that Congress has granted the agency broader 
authority, it is reasonable in this case, where EPA can craft criteria 
to identify closures that may be protective and thus warrant a closer 
evaluation, to rely on that broader authority.
    Under this provision, EPA is not exempting a facility from the 
requirement to demonstrate that a unit closure meets the performance 
standards in Sec.  257.102, or from agency oversight, but only delaying 
application of the requirement until the Agency can resolve the 
outstanding legal and factual issues. EPA is also deferring only the 
requirement that a closed unit achieve compliance with the closure 
performance standards. To mitigate any potential risks, all other 
applicable requirements, including the requirements for groundwater 
monitoring and corrective action would continue to apply to these 
units. Further EPA's existing authorities to respond to urgent threats 
to human health or the environment also remain available, should the 
need arise. See, e.g., 42 U.S.C. 6973.
i. Requirement for Legacy CCR Surface Impoundments To Close
    The final rule continues to require legacy CCR surface impoundments 
to close. As EPA explained in the proposal, the USWAG decision has 
effectively resolved this issue. No commenter submitted any evidence to 
demonstrate that the risks associated with these units are any lower 
than they were in 2018 when the Court decided that closure of all 
unlined and clay-lined impoundments was required by RCRA section 
4004(a) or that the risks posed by legacy CCR surface impoundments are 
any lower than those at the currently regulated inactive impoundments 
at active facilities. If anything, more recent information indicates 
that a greater number of legacy CCR surface impoundments are more 
likely to have leaked even higher levels of contaminants than the 
operating impoundments modeled in 2014. See Unit III.A.
    No commenter has identified any legacy CCR surface impoundment with 
a composite liner that meets the requirements of Sec.  257.71. Based on 
the data gathered since 2015 from the currently regulated CCR unit 
universe, the Agency considers it highly unlikely that any legacy CCR 
surface impoundment has such a liner. EPA analyzed the list of inactive 
CCR facilities compiled based on comments received in response to the 
ANPRM and this rulemaking and knows that almost all these facilities 
were opened prior to 1990 (one facility opened in 1996) before 
composite liner systems were typically installed. Unless legacy CCR 
surface impoundments are very different than impoundments at active 
facilities, EPA expects all units of this age to be unlined as defined 
by Sec.  257.71.
    The D.C. Circuit has also already rejected arguments that EPA can 
avoid requiring CCR surface impoundments to close based on claims that 
``all impoundments aren't leaking.''

    The EPA and Industry Intervenors assert that the composite 
lining required for new units is not needed for existing units 
because most unlined impoundments do not leak, and an unlined 
impoundment that is not leaking is not dangerous. Industry 
Intervenors emphasize that the record suggests that ``almost two-
thirds of unlined impoundments do not leak,'' and they assert that 
``appropriate controls on impoundments that do leak'' suffice to 
meet RCRA's ``no reasonable probability'' standard. The EPA 
underscores that it made no finding of any ``reasonable probability 
that each and every unlined impoundment will, in fact, result in 
adverse effects on health and the environment.'' It insists that 
RCRA's ``no reasonable probability'' standard is met by the Rule's 
provisions for ``extensive monitoring of groundwater to detect 
constituent leaking,'' id. at 83, and ``immediate action to stop 
that leak,'' ``redress that leak,'' and to close the site as soon as 
a harmful leak is detected.

USWAG, supra at 427. The Court summarily rejected these arguments.

    It is inadequate under RCRA for the EPA to conclude that a major 
category of impoundments that the agency's own data show are prone 
to leak pose ``no reasonable probability of adverse effects on 
health or the environment,'' 42 U.S.C. Sec.  6944(a), simply because 
they do not already leak.

Id. This holding largely rests on a legal conclusion of what RCRA 
section 4004(a) requires, which Congress did not alter when it amended 
the statute in the WIIN Act.
    The Court similarly rejected arguments that reliance on the part 
257 corrective action provisions to clean up releases can effectively 
substitute for a national requirement to close impoundments, or that 
corrective action alone is sufficient to meet the RCRA section 4004(a) 
standard. As the Court explained, that argument focuses on the wrong 
risks and addresses only half of the statutory standard. The 
contamination of a potential source of drinking water is itself an 
adverse effect on the environment, and the statutory requirement to 
ensure there will be no reasonable probability of adverse effects on 
health or the environment requires the Agency to take measures based on 
the risks to prevent this harm from occurring in the first place. It is 
not enough to remediate the contamination before it reaches an off-site 
receptor.

    In defending the Rule here, the EPA looks at too narrow a subset 
of risk information and applies the wrong legal test.
    The Final Rule's approach of relying on leak detection followed 
by closure is arbitrary and contrary to RCRA. This approach does not 
address the identified health and environmental harms documented in 
the record, as RCRA requires.
. . .
    RCRA requires the EPA to set minimum criteria for sanitary 
landfills that prevent harm to either ``health or the environment.'' 
The EPA's criteria for unlined surface impoundments, limited as they 
are to groundwater monitoring for contaminant levels keyed to human 
health, only partially address the first half of the statutory 
requirement.
. . .
    But here, too, the EPA has failed to show how unstaunched 
leakage while a response is pending comports with the `no reasonable 
probability' standard.

Id. at 429-430, 431 (emphasis added). None of this has changed. Nor has 
any commenter identified any unique

[[Page 39027]]

characteristic of legacy impoundments that makes any of the Court's 
analysis irrelevant or inapplicable. Although some commenters continue 
to claim that their units are heavily vegetated or developed and that 
reopening or other removal/remediation activities may disrupt current 
use of the land, no commenter submitted any data or analysis to 
demonstrate that removal or remediation activities would be more 
detrimental to health and the environment than not cleaning up the 
contaminated groundwater in the aquifer or taking measures to prevent 
the legacy CCR surface impoundment from continuing to contaminate the 
aquifer. Moreover, the fact that some impoundments have become heavily 
vegetated or redeveloped does not mitigate the risks these unlined 
legacy CCR surface impoundments continue to pose.
    The same is true for those commenters alleging that the closure of 
legacy CCR surface impoundments would itself present greater risks than 
leaving the disposal unit in its existing state; none presented any 
data or analysis, stating instead that possible effects were self-
evident. However, EPA notes that most of these comments appear to have 
been premised on the assumption that closure by removal would be 
required. As discussed in the next section, EPA is not prohibiting 
legacy CCR surface impoundments from closing with waste in place, 
provided all of the performance standards in Sec.  257.102(d) have been 
met.
    EPA also cannot, as the commenters suggest, proceed exclusively on 
the basis of site-specific assessments and forego a nationwide risk 
assessment, national closure requirement, or universal performance 
standards for closure. When Congress amended the statute in 2016, it 
added a permitting component but retained without revision the 
requirements in RCRA sections 1008(a)(3) and 4004(a) that EPA establish 
minimum national standards (``criteria'') by regulation. The statute 
relies on these criteria in several provisions, including as the 
standard EPA must use to evaluate State programs, to issue permits, and 
to determine whether a CCR unit is a sanitary landfill or an open dump. 
See, 42 U.S.C. 6945(d)(1)(B), (d)(1)(D), (d)(3), (d)(6). The D.C. 
Circuit has also effectively confirmed the continued necessity of 
national criteria; if the Court believed that the WIIN Act obviated the 
need to comply with RCRA section 4004(a) it would have granted EPA's 
request for an abeyance or dismissed the case as moot. That it did 
neither demonstrates that the Court believed that its opinion would 
remain relevant. See, USWAG, 901 F3d at 436-437 (denying EPA's request 
for voluntary remand because ``this claim involves a question--the 
scope of EPA's statutory authority--that is intertwined with any 
exercise of agency discretion going forward.'')
    Accordingly, the final rule requires all legacy CCR impoundments to 
close.
ii. Deferral for Legacy CCR Surface Impoundments Under Critical 
Infrastructure
    As noted above, several commenters stated that some inactive 
facilities have been redeveloped and that the CCR surface impoundments 
are now located beneath critical infrastructure. These commenters 
claimed that requiring closure of units beneath infrastructure could 
adversely impact grid reliability, business operations, or other 
necessary public services and suggested EPA create exemptions or 
extensions for these units. For example, one commenter stated that 
closure of units located under other structures is not feasible as EPA 
has proposed. The commenter further explained that:

the issue is applicable and even more pronounced with respect to 
legacy impoundments. By definition legacy CCR surface impoundments 
are located at inactive sites that in some instances have been 
partially or completely redeveloped. As a result, former legacy 
units at this stage may be completely inaccessible due to 
vegetation, new infrastructure like pipelines or transmission lines 
that cannot be disturbed without disrupting operations, active CCR 
units, buildings, or other obstacles to access. If EPA proceeds to 
issue the proposal EPA must address such accessibility issues.

    Other commenters supported the decision not to propose an exemption 
from the closure requirements for legacy CCR surface impoundments 
beneath redevelopments or infrastructure, based on the risks that these 
sites can present, and provided specific examples of such sites. Two of 
the examples related to a situation in which active CCR disposal units 
were built on top of former CCR surface impoundments (i.e., overfills). 
In one instance, the commenter described a site where an unlined CCR 
surface impoundment had been closed by partially draining the 
impoundment and constructing a new CCR landfill (98.9 acres), two 
stormwater ponds and a leachate pond (10.8 acres), and a materials 
handling area (4.4 acres) on top of the former impoundment. According 
to the commenter, the facility claimed that the closed impoundment 
rather than any of the active CCR units, was responsible for SSIs 
detected in its groundwater monitoring. The commenter referenced 
documents on the facility's CCR website which explained that:

    Although it has not received sluice water since 2008, the CCR in 
the former Main Pond continues to receive, store, and discharge 
water, primarily groundwater entering the CCR through the sides of 
the filled valley. Groundwater flow into the CCR in the former Main 
Pond drains downward and outward to the east through the toe drain 
system under the dam.

The commenters explained that overfills can increase groundwater 
contamination from the underlying unit by reducing the hydraulic 
gradient and increasing the waste and water contact time. They stated 
that this has been documented by both an EPRI study and groundwater 
monitoring at a specific overfill that showed steady to gradually 
increasing concentrations of CCR related constituents in the landfill 
monitoring wells, rather than the predicted decline in concentrations 
of CCR-related constituents from the closure of the underlying surface 
impoundment.
    As an initial matter, under both the existing definitions and the 
definitions in the final rule a legacy CCR surface impoundment could 
not be located below an active CCR unit. A legacy impoundment is 
located at an inactive facility, and the presence of an active CCR unit 
means that the facility is active, not inactive. See, Sec. Sec.  
257.50(b), 257.53 (definition of active facility). This means that in 
the example described by the commenter the surface impoundment 
underneath the active landfill is an inactive CCR surface impoundment 
at an active facility, and would be considered a ``regulated unit'' 
subject to the existing requirements in part 257, rather than this 
final rule.
    In any event, EPA disagrees that its proposal did not adequately 
account for the circumstance in which a legacy CCR surface impoundment 
may be challenging to access, such as where the impoundment is located 
beneath infrastructure or buildings. In contrast to the comments 
received with respect to CCRMU, no commenter provided a concrete 
example in which closure of a legacy CCR surface impoundment would 
interfere with critical infrastructure. The overwhelming majority of 
commenters provided concrete examples of concerns with respect to CCRMU 
and then concluded that EPA needed to address the issue equally for 
legacy CCR surface impoundments. The most concrete example of potential 
interference with critical infrastructure is the reference to ``new 
infrastructure like pipelines or transmission lines that cannot be 
disturbed without disrupting

[[Page 39028]]

operations'' quoted above. But even in that case the commenter provided 
no explanation of the factual basis for the conclusion that over the 
five to 15 years the existing regulations provide to complete closure 
the facility could not schedule the outages necessary to move pipelines 
or transmission lines, and conduct the closure in stages as necessary 
to accommodate scheduling any necessary outages.\62\ In addition, as 
discussed in the next Unit of the preamble, EPA has extended the 
deadline to initiate closure to 48 months from promulgation. The amount 
of time provided by these deadlines is more than adequate to account 
for any accessibility issues. Further, EPA has been regulating 
utilities under multiple environmental statutes for decades and 
reliability issues are often raised when regulations are promulgated, 
but EPA is unaware of situations where those reliability concerns have 
been realized in the form of electric blackouts caused by compliance 
with Federal environmental standards. In this case, in the unlikely 
event closure of a legacy CCR surface impoundment cannot occur within 
the regulatory timeframe without creating a demonstrated reliability 
concern, the Agency will work with the facility, the relevant RTO, and 
other relevant Federal agencies to ensure proper closure occurs without 
causing the power to go out.
---------------------------------------------------------------------------

    \62\ Electric generating facilities are required to schedule and 
agree upon boiler shutdown periods with their Regional Transmission 
Organization (RTO) to ensure grid reliability. Most plants have 
regular boiler shutdowns on an annual basis with a more substantial 
one every few years. Since regular boiler shutdowns are already 
scheduled, the facility can plan the closure construction around the 
already scheduled outage; however, the outage may need to be 
extended depending on the work. The RTOs require various lead times 
of consultation or notice prior to any retirements, outages, or 
extended periods of non-operation.
---------------------------------------------------------------------------

    Finally, as noted above EPA received a substantial number of 
comments requesting the agency not require facilities to ``re-close'' 
any unit that had already completed closure. This final rule does not 
mandate that any previously closed unit automatically re-close. But, as 
described in the next section, the final rule does require all legacy 
CCR surface impoundments to meet the performance standards in Sec.  
257.102, although as discussed above, some may not be required to do so 
until permitting. EPA does not consider this to be equivalent to a 
requirement to ``re-close'' as, depending on the site conditions, 
facilities may be able to implement engineering measures, such as the 
installation of slurry walls to prevent groundwater infiltration, to 
address any deficits without removing the cover system or entirely re-
closing the whole impoundment.
iii. Requirement To Comply With Performance Standards in Sec.  257.102
    As discussed above, consistent with USWAG and the proposed rule, 
this final rule requires that the closure of legacy CCR surface 
impoundments meet the performance standards in either Sec.  257.102(c) 
or (d). Under this final rule, all closures initiated after the 
effective date of this rule, as well as those that were not completed 
prior to the effective date of this rule, will need to comply with 
these requirements.
    And in general, the same is true with respect to closures that were 
completed prior to the effective date of this rule. As discussed 
previously, a facility that can certify that its prior closure meets 
the performance standards in Sec.  257.102(c) only needs to post the 
documentation that it meets the standard. Similarly, if a facility can 
demonstrate that the closed unit meets the requirements under Sec.  
257.102(d), EPA will consider them to be closed and the only 
requirements that will be applicable are those that apply to closed 
units under post-closure care--such as groundwater monitoring, and if 
necessary, corrective action. EPA never intended to require facilities 
that otherwise met the closure standards to go through the process 
again and re-close the unit. In addition, where the facility was 
subject to standards that are different than the Federal CCR closure 
standards (e.g., if the closure were conducted as part of a CERCLA 
cleanup or State order) but are otherwise equivalent in terms of 
mitigating the risks, the requirement to meet the Sec.  257.102 
standards will be deferred to permitting, where a closure equivalency 
determination will be made.
    In response to EPA's proposal that all legacy CCR surface 
impoundments comply with Sec.  257.102, many commenters again 
reiterated their request that EPA exempt any unit that has either 
completed closure or is in the process of closing pursuant to State law 
(e.g., solid waste permit, consent orders or decrees). Commenters also 
requested EPA to exempt any site that had closed as part of a cleanup 
conducted pursuant to another Federal requirement, such as CERCLA or 
RCRA subtitle C. These commenters stated that EPA had failed to 
demonstrate that these units posed any risk as a consequence of the 
lack of ponded water, and that ``re-closure'' of these previously 
closed units is consequently unnecessary and overly burdensome.
    By contrast, several commenters supported EPA's proposal to require 
all legacy CCR surface impoundments to comply with the performance 
standards in Sec.  257.102, even if the closure was previously approved 
by a State regulatory agency. These commenters pointed to EPA's 
conclusions in 2015 that significant gaps remain in many State 
programs; that some programs provide minimal or no regulatory oversight 
of CCR units; and that most CCR surface impoundments were permitted 
exclusively under NPDES or other surface water pollution prevention 
programs. See, 80 FR 21324-21325. The commenters also included recent 
examples of closures approved by various State agencies that were not 
consistent with the Federal closure standards including: (1) Ohio's 
approval of the closure of an unlined CCR surface impoundment at the 
Gavin Plant, which EPA subsequently estimated could be sitting in 
groundwater as high as 64 feet deep in some locations post closure and 
that as much as 8.2 million cubic yards (or as much as 40% of the CCR 
in the Fly Ash Resevoir) could still be saturated--and would remain so 
indefinitely; (2) Alabama's issuance of several permits authorizing 
several facilities to close unlined CCR surface impoundments with large 
quantities of free liquids and saturated CCR remaining in the closed 
units; and (3) Kentucky's permit authorizing the closure of an unlined 
CCR surface impoundment by partially draining the impoundment and 
constructing a new CCR landfill (98.9 acres), two stormwater ponds and 
a leachate pond (10.8 acres), and a materials handling area (4.4 acres) 
on top of the impoundment. The CCR in the underlying closed impoundment 
continues to receive, store, and discharge water, primarily groundwater 
entering the CCR through the sides of the filled valley, drains 
downward and outward to the east through the toe drain system under the 
dam.
    Finally, several commenters requested that EPA prohibit legacy CCR 
surface impoundments from closing in place under Sec.  257.102(d).
    EPA disagrees that legacy CCR surface impoundments should be 
prohibited from closing with waste in place in accordance with Sec.  
257.102(d). The commenters did not demonstrate that legacy impoundments 
could never meet the performance standards in Sec.  257.102(d) or 
identify unique characteristics or risks of legacy impoundments that 
would not be adequately addressed by compliance with those provisions. 
Both clean closure and closure with waste in place can be equally 
protective, provided that all of the requisite performance

[[Page 39029]]

standards in Sec.  257.102 are met. The final rule therefore requires 
legacy impoundments to comply with the same requirements applicable to 
other inactive impoundments, that is, to close in accordance with 
either Sec.  257.102(c) or (d).
    If all of the performance standards for clean closure and the 
performance standards for closure with waste in place can be met, an 
owner or operator may determine which alternative is appropriate for 
their particular unit. The regulations do not require an owner or 
operator to use one closure option over the other in such situations. 
However, the facility must meet all the performance standards for the 
option it has selected, and if it cannot meet all of the performance 
standards for one option, then it must meet all of the performance 
standards for the other option. 40 CFR 257.102(a) (specifying that 
``[c]losure of a CCR landfill, CCR surface impoundments . . . [m]ust be 
completed either by leaving the CCR in place and installing a final 
cover system or through removal of the CCR and decontamination of the 
CCR unit, as described in paragraphs (b) through (j) of this 
section.''). For example, if the facility is unable to meet the 
performance standards for closure with waste in place for a particular 
unit (or portion of a unit), it must close the unit by removal (or that 
portion). Whether any particular unit or facility can meet the 
performance standards is a fact and site-specific determination that 
will ultimately depend on a number of factual and engineering 
considerations, such as the hydrogeology of the site, the engineering 
of the unit, and the kinds of engineering measures available.
    As discussed in the preceding section, this final rule does not 
require previously closed legacy CCR surface impoundments to 
automatically ``re-close.'' Rather, consistent with the proposal, 
facilities will be required to ensure that all closed legacy CCR 
surface impoundments meet the performance standards in Sec.  257.102(c) 
or (d). To the extent any deficit can be remedied by supplementary 
engineering methods, that would be all that is required.
(a) Closure of Legacy CCR Surface Impoundments Under State Law
    EPA continues to disagree that it would be appropriate to exempt 
any legacy CCR surface impoundment that has completed closure or is 
currently in the process of closing pursuant to State requirements. As 
EPA repeatedly explained in the proposal, Congress established a 
specific process that would authorize State requirements to operate in 
lieu of the Federal CCR regulations, and it would be inappropriate for 
EPA to substitute its own process to achieve the same ends. Under the 
Congressionally mandated process, a State must obtain EPA approval, in 
whole or in part, of its CCR permit program, pursuant to RCRA section 
4005(d). 42 U.S.C. 6945(d). Those provisions expressly identify the 
standard EPA must use to evaluate a State program including, where 
applicable, alternative technical criteria that differ from the Federal 
CCR regulations, along with requirements for EPA to review approved 
programs and, if necessary, to withdraw approval. Finally, the statute 
expressly provides that in the absence of a permit issued under an 
approved State program, the Federal criteria apply to all CCR units. 42 
U.S.C. 6945(d)(6). These provisions reflect Congress' considered 
judgment of the appropriate legal structure and relationship between 
State and Federal requirements, and it is not appropriate for EPA to 
effectively establish its own alternative.
    In any event, EPA lacks the record necessary to support a broad 
exemption for all closures under any State requirement. As discussed in 
more detail below. the information currently available does not 
demonstrate that all closures conducted under State authority ``ensure 
there is no reasonable probability of adverse effects on health or the 
environment.'' 42 U.S.C. 6944(a).
    First, commenters' arguments appear to be premised largely on the 
existence of a State solid waste program with the attributes of the 
municipal solid waste landfill requirements adopted and approved well 
after those dates. But as some commenters acknowledged, many legacy 
impoundments closed well before any State had developed such 
regulations--e.g., during 1970s-1990s.\63\ EPA has no evidence 
demonstrating the protectiveness of State requirements during this 
period. However, the results of the joint U.S. Department of Energy 
(DOE) and EPA study completed in 2006, ``Coal Combustion Waste 
Management at Landfills and Surface Impoundments, 1994-2004,'' are not 
encouraging. Only 19% (three out of 19) of the surveyed surface 
impoundment permits included requirements addressing groundwater 
protection standards (i.e., contaminant concentrations that cannot be 
exceeded) or closure/post-closure care. The EPA/DOE report also 
concluded that approximately 30% of the net disposable CCR generated 
was potentially exempt from all State solid waste permitting 
requirements (EPA/DOE Report at pp 45-46). For example, at the time of 
the report, Alabama did not regulate CCR disposal under any State waste 
authority and did not have a dam safety program. Finally, the report 
found that a number of States only regulated surface impoundments under 
Clean Water Act authorities, and consequently primarily addressed the 
risks from effluent discharges to navigable waters, but did not require 
liners or groundwater monitoring.
---------------------------------------------------------------------------

    \63\ As discussed previously, if an impoundment contained CCR 
and liquids on or after October 19, 2015, it is considered a legacy 
impoundment under these regulations even if the unit is considered 
to have been closed under state law.
---------------------------------------------------------------------------

    As part of developing the 2015 CCR Rule, EPA independently reviewed 
State statutes and regulations, with a more detailed focus on the 16 
States responsible for approximately 74% of the CCR generated in 2009. 
See 80 FR 21324. This review identified some programs that provided 
minimal or no regulatory oversight of CCR units. For example, Arizona, 
New Mexico, and Utah had no regulations applicable to CCR units or 
entirely exempted CCR from State regulations governing solid waste. 
Similarly, Mississippi, Montana, and Texas (the largest coal-ash 
producer) exempted the on-site disposal of CCR (as ``nonhazardous 
industrial solid waste'') from some or all key requirements, such as 
permits or groundwater monitoring. Such exemptions covered most of the 
disposal of CCR within the State, as the majority of utilities dispose 
of their CCR on-site. Other States, such as Florida, Indiana, Ohio and 
Pennsylvania, exempted CCR landfills or ``monofills'' from many 
requirements. For example, Indiana regulations considered surface 
impoundments that are dredged at least annually to be ``storage units'' 
that are exempt from solid waste regulations, including from corrective 
action requirements. Many of these States were among the leading 
generators of CCR wastes at the time. In total, EPA estimated that in 
2015, approximately 20% of the net disposable CCR was entirely exempt 
from State regulatory oversight.
    However, EPA concluded in 2015 that most States regulated the 
management of CCR to varying degrees, although the particular 
requirements varied significantly. Most CCR surface impoundments were 
permitted exclusively under NPDES or other surface water pollution 
prevention programs. In these States, requirements to protect 
groundwater, such as liners or groundwater monitoring systems, were 
frequently less robust than the corresponding requirements applicable 
to CCR landfills.

[[Page 39030]]

    EPA did not specifically evaluate State closure requirements in 
2015. However, EPA's findings with respect to groundwater monitoring 
requirements suggests that it is unlikely States considered the extent 
to which a surface impoundment would remain saturated by groundwater 
after closure. In 2015 EPA had only limited anecdotal evidence on the 
status of groundwater monitoring in six States, including four States 
that are among the leading CCR generators. After the Kingston TVA spill 
in December of 2008, groundwater monitoring wells were installed at 12 
of Illinois's existing surface impoundments, almost doubling the number 
of monitored surface impoundments in the State. However, 55 additional 
surface impoundments, both active and inactive, still lacked 
groundwater monitoring systems. In Ohio, 44 CCR units, out of a total 
of 57 CCR units in the State (42 surface impoundments and 15 landfills) 
still lacked groundwater monitoring in 2015, even though all the 
surface impoundments were permitted decades ago under Ohio's NPDES 
program. Ohio acknowledged in their comments that the extent of 
groundwater risks in the State was poorly documented, as 40 out of 44 
unlined CCR units did not have a groundwater monitoring system. Some 
State programs also authorized a buffer zone or a ``zone of 
discharge,'' which allows the facility to defer remediation of 
groundwater contamination for some period of time, usually until the 
contaminant plume has migrated to the facility site boundary. Florida, 
Illinois, North Dakota, and Tennessee were among the States with such a 
regulatory provision.
    EPA acknowledges that some States have substantially revised their 
programs since 2015, but this is not universal. In addition, although a 
few States provided further information that was not available to EPA 
in 2015 about their programs in response to the proposal, most did not. 
For the most part, commenters offered general assertions that State 
regulatory authorities have considered the site-specific conditions and 
determined that the closure or closure plan meets the necessary 
requirements for addressing risk, and that EPA should not second guess 
these decisions, but provided little, if any, evidence that would 
support a wholesale exemption for any closure conducted in accordance 
with State requirements.
    At the same time, as discussed above, several commenters provided 
examples of recent (post-2015) State-authorized closures that are 
significantly less protective than Sec.  257.102. For example, at least 
two States responsible for a significant percentage of the CCR 
generated annually, Ohio and Kentucky, recently (i.e., after 2015) 
allowed facilities to close their impoundments by removing the CCR from 
the impoundment, but did not require groundwater monitoring to 
determine whether groundwater contamination remained at the site. Under 
the CCR regulations, closure by removal is only considered complete 
with documentation that all Appendix IV constituent concentrations are 
below the GWPS in two consecutive groundwater monitoring sampling 
events.
    More to the point, as EPA explained in the proposal, the record 
clearly shows that significant numbers of CCR surface impoundments were 
constructed with at least some portion of the unit actually in the 
aquifer beneath it, or otherwise consistently saturated by groundwater 
or surface water migrating into the unlined impoundment. Many of these 
units were closed without addressing the liquids that continued to 
saturate the CCR, and the free liquids that remained or the fact that 
the unit continues to impound water--in some cases with full approval 
from the State. This is especially likely for closures that occurred 
prior to 2015. As noted previously, a 2006 DOE/EPA report concluded 
that only 19% of the surveyed surface impoundment permits included 
requirements addressing groundwater protection standards (i.e., 
contaminant concentrations that cannot be exceeded) or closure/post-
closure care, and approximately 30% of the net disposable CCR generated 
was potentially exempt. The risks associated with such closures can be 
substantial, as discussed in Unit III.A of this preamble. Ultimately, 
under the Federal CCR regulations what determines whether a unit meets 
the definition of an inactive CCR impoundment or a closed CCR 
impoundment--and what determines whether the unit continues to present 
a reasonable probability of adverse effects on health and the 
environment--are the conditions that remain and the resulting risks, 
rather than whether a facility or even a State regulatory authority has 
labeled the unit as ``closed.''
    For all of these reasons, EPA cannot exempt: (1) All units that 
have closed consistent with State requirements, or (2) All units that 
have started closure or have had a closure plan approved under State 
requirements prior to the effective date of the final rule.
(b) Deferral of Certain Completed Closures to Permitting
    A few commenters provided examples of closure that they believed 
were substantially equivalent to closures in accordance with Sec.  
257.102, because they involved substantial regulatory oversight, a 
site-specific risk assessment, and general consistency between the 
programs on the standards to be applied. These included closures under 
CERCLA and an approved State's RCRA subtitle C program. According to 
these commenters, it is a near certainty that there will be slight 
differences in the way the closure activities were designed or 
conducted when compared to Sec.  257.102, but because the closure 
activities accomplish the same environmental goals and meet the same 
ultimate performance standards with respect to avoiding groundwater 
impacts, there is little to be gained by duplicative closure activities 
under the Federal CCR regulations. Another commenter provided a copy of 
a Consent Order entered in State court governing the closure of CCR 
surface impoundments at seven sites across the State. The commenter 
also provided copies of several human health and ecological risk 
assessments that were conducted to support the State's approval of the 
closures, along with various third-party reports. The commenter 
concluded that based on this factual record, it is unnecessary to 
subject these units to the existing closure criteria for CCR surface 
impoundments in Sec. Sec.  257.101 and 257.102.
    EPA agrees that closures conducted as part of a CERCLA or RCRA 
subtitle C response action would normally be expected to be consistent 
with the performance standards in Sec.  257.102; the CCR closure 
regulations were based on the closure regulations for hazardous waste 
facilities, and the CCR regulations would normally be considered ARARs 
under CERCLA for any closure of a CCR facility after 2015. 
Consequently, these facilities may ultimately be able to support a 
certification of compliance with Sec.  257.102. But, as the commenters 
noted, there can be slight variations in how the standards are applied, 
and a facility may consequently not be confident that it can support a 
certification.
    Nor are these the only closures that may be substantially 
equivalent. As the commenters' examples demonstrate, State 
requirements, even where different, can result in closures that are 
equally as protective as those conducted in accordance with Federal 
requirements.
    However, as the commenters noted it is a near certainty that there 
will be differences in the way the closure activities were designed or 
conducted when compared to Sec.  257.102. EPA does

[[Page 39031]]

not believe that it can craft an exemption that could encompass all 
these potential variations. Nor does EPA believe that it could develop 
criteria that are sufficiently precise that regulated entities could 
determine whether alternative requirements ultimately accomplish the 
same environmental goals and meet the same ultimate performance 
standards as the Federal requirements. But EPA has detailed criteria to 
identify whether a closure is potentially as protective as those 
conducted in accordance with Sec.  257.102, and which therefore warrant 
a closer evaluation; closures that meet these criteria will be deferred 
until a permitting authority can evaluate the adequacy of the closure.
    The closures described above all share certain features such as the 
risks at the site have been fully evaluated by a regulatory authority 
and carefully addressed with oversight by a regulatory authority. Even 
though the specific requirements may differ from Sec.  257.102, there 
is nevertheless reason to believe that the closure will be protective, 
at least in the interim until a permitting authority can evaluate the 
adequacy of the closure to the CCR closure requirements. Based on these 
considerations, EPA is limiting this deferral to closures where the 
facility can document that it meets specific conditions. First, the 
deferral is limited to circumstances in which a regulatory authority 
played an active role in overseeing and approving the closure 
activities. EPA considers a ``regulatory authority'' to include a State 
or Federal permit, an administrative order, or consent order issued 
after 2015 under CERCLA or by an EPA-approved RCRA State program. The 
permitting or other authority must have required groundwater monitoring 
to ensure there was no contamination coming from the unit that is not 
addressed by corrective action.
    Second, to support deferral of evaluation of a prior closure of a 
legacy CCR surface impoundment as substantially equivalent, the 
facility with a surface impoundment that closed with waste in place 
must document that free liquids have been eliminated, consistent with 
the standard in Sec.  257.102(d)(2)(i). This requirement directly 
addresses the reason that EPA has concluded that many previously 
completed closures do not meet the standard in RCRA section 4004(a).
    Third, a facility must document that it had installed a groundwater 
monitoring system and performed groundwater monitoring that meets a 
subset of the performance standards found in Sec.  257.91(a). 
Specifically, the facility must demonstrate that the groundwater 
monitoring system was capable of: (1) Accurately representing 
background water quality; (2) Accurately representing the quality of 
water passing the waste boundary; and (3) Detecting contamination in 
the uppermost aquifer. Finally, the groundwater monitoring system must 
have monitored all potential contaminant pathways. These are the same 
subset of standards that apply to a facility certifying that its 
closure by removal completed prior to the effective date of this final 
rule meets the performance standards in Sec.  257.102(c).
    Fourth, a facility would need to demonstrate that a site-specific 
risk assessment was conducted or approved by the regulatory authority 
prior to (or as part of) approving the closure, and that the closure 
and any necessary corrective action has been overseen by the regulatory 
authority, pursuant to an enforceable requirement.
    These criteria are generally consistent with the criteria a 
commenter suggested to identify closures under other authorities that 
would be equivalent to those conducted in accordance with Sec.  
257.102. These included that the facility had installed a groundwater 
monitoring system and performed groundwater monitoring and analysis in 
accordance with Sec. Sec.  257.90 through 257.95 and was conducting any 
necessary remediation in accordance with Sec. Sec.  257.96 through 
257.98, pursuant to an enforceable requirement. Although the commenter 
proposed these to serve as a basis for an exemption, EPA considers they 
are equally relevant to identifying decisions that can be deferred for 
future evaluation.
    Fifth, the facility would be required to prepare and include 
documentation in the applicability report and operating record, 
demonstrating that it has met these criteria and is eligible for 
deferral. This would include all relevant specifics such as State 
permit, order, data, groundwater monitoring results, etc. This must be 
certified by the owner/operator or an authorized representative using 
the same language in Sec.  257.102(e).
    When it comes time for the permit authority to evaluate the 
closure, EPA intends to rely on the permit application process as the 
primary mechanism to collect the information to allow a determination 
to be made as to whether a legacy CCR surface impoundment that closed 
under these alternative standards did so in compliance with the 
requirements of Sec.  257.102. The permit application process is a 
well-established system for reviewing the types of groundwater, soil 
and other sampling and analytical data that will typically be required 
in determining the ``equivalency'' of alternative closures.
    When the permit application is called in, the facility must provide 
sufficient information, including data on contaminant levels in 
groundwater, to demonstrate that the applicable Sec.  257.102 standards 
have been met. EPA or a Participating State Director will review the 
information to determine whether the ``equivalency'' of the closure has 
been successfully demonstrated. If EPA determines that the closure has 
met the appropriate part 257 closure standard, EPA will issue a permit. 
If EPA or a Participating State Director determines that the closure 
does not meet the part 257 standards, the owner or operator will be 
required to submit a permit application containing all the applicable 
information for an operating permit, and EPA or a Participating State 
Director will issue a permit that contains the specific requirements 
necessary for the closed unit to achieve compliance with Sec.  257.102.
iv. Closure Compliance Deadlines for Legacy CCR Surface Impoundments
(a) Initiation of Closure for Legacy CCR Surface Impoundments
    EPA proposed that legacy CCR surface impoundments be subject to the 
existing requirement to initiate closure that are applicable to other 
unlined CCR surface impoundments because, as discussed in the proposed 
rule and in Unit III.B.2.c of this preamble, the current record 
indicates that legacy CCR surface impoundments are largely, if not 
entirely, unlined. Specifically, EPA proposed that owners or operators 
of legacy CCR surface impoundments initiate closure no later than 12 
months after the effective date of the final rule because EPA 
anticipated 12 months being sufficient time for owners or operators to 
identify and delineate the legacy CCR surface impoundment, determine 
relevant engineering information (e.g., structural stability), 
characterize the site's hydrogeology and other characteristics, and 
determine whether any of the uppermost aquifer has been contaminated. 
As explained in the proposed rule, EPA acknowledged that most of this 
information would be obtained through compliance with the proposed 
groundwater monitoring and corrective action requirements.
    In the proposed rule, EPA solicited comment on whether the 
regulations should provide owners and operators the option to retrofit 
a legacy CCR surface impoundment in accordance with the retrofit 
requirements in Sec.  257.102(k) as an alternative to

[[Page 39032]]

requiring the closure of a legacy CCR surface impoundment.
    As stated in Unit III.B.2.g, generally commenters on the proposed 
rule supported requiring legacy CCR surface impoundments to close in 
accordance with the existing requirements. However, some commenters 
disagreed that closure was appropriate for certain legacy CCR surface 
impoundments, including those units underneath infrastructure needed to 
support current activities, those that had completed or currently 
undergoing closure, and those units that have been demonstrated not to 
pose unacceptable risk.
    Most commenters stated that the proposed deadline for the 
initiation of closure was infeasible due to the factors listed in Units 
III.B.2.a.ii and III.B.2.g of this preamble (e.g., labor shortages, 
seasonality, limited contractor availability, overlapping regulatory 
requirements) and should be extended in consideration of those factors 
as well as to allow for the incorporation of the groundwater monitoring 
data.
    No commenters provided feedback on whether the regulations should 
allow owners and operators to retrofit a legacy CCR surface 
impoundment.
    For the reasons explained in the proposed rule as well as Unit 
III.B.2.g, EPA continues to conclude that the closure requirements in 
the existing rule are generally appropriate for legacy CCR surface 
impoundments. However, as explained in Unit III.B.2.g, EPA recognizes 
that in specific situations, mandatory closure of a legacy CCR surface 
impoundment by the deadline may cause more harm than benefits to human 
health and the environment. Based on information provided by the 
commenters and experience with the implementation of the 2015 CCR Rule 
(i.e., regulation of inactive CCR surface impoundments), EPA finds that 
these situations are limited to those in which the legacy CCR surface 
impoundment has completed closure under a State authority and those in 
which the unit is beneath infrastructure necessary for current 
activities.
    For additional closure requirements of a legacy CCR surface 
impoundment, the decision to require reclosure will be deferred until a 
permitting authority is authorized to issue CCR permits to the 
facility, at which point, the permitting authority will be able to look 
at site-specific factors and evidence to decide if reclosure is 
necessary to protect human health and the environment. EPA concludes 
that this approach will mitigate adverse impacts to local communities 
and the environment, including environmental justice concerns that may 
result from activities associated with reclosing a facility that is not 
contaminating groundwater or posing other risk to human health and the 
environment, such as increased traffic, increased greenhouse gas 
emissions, habitat loss, loss of native vegetation, water consumption, 
and additional waste generation.
    When the legacy CCR surface impoundment is beneath infrastructure 
vital to the continuation of activities, such as beneath a substation, 
the initiation of closure will be deferred until the infrastructure is 
no longer needed or the closure of the facility, whichever is sooner. 
This approach protects human health and the environment while 
appropriately accounting for the need for operational continuity and 
reliability.
    As explained in Unit III.B.2.g, EPA acknowledges the benefit of 
allowing owners or operators the time needed to incorporate groundwater 
monitoring data into the closure plan. Additionally, as stated in the 
proposed rule, EPA acknowledges the importance of using information 
gained by compliance with the groundwater monitoring and corrective 
action requirements to inform closure decisions and therefore the 
initiation of closure. For the reasons explained in Unit III.B.2.f, EPA 
is extending the deadline for the groundwater monitoring and corrective 
action requirements to a single deadline of no later than 30 months 
from the effective date of the final rule. As such, the initiation of 
closure is being extended as well. To ensure owners or operators have 
enough groundwater monitoring data to draw conclusions about 
seasonality impacts on groundwater levels and flow and the source of 
any potential groundwater contamination in the area, EPA is finalizing 
a deadline of no later than Monday, May 8, 2028, which is 42 months 
from the effective date of the final rule. This is codified in the 
regulatory text at Sec.  257.101(e)(1).
    EPA is finalizing the application of the existing requirements to 
initiate closure to legacy CCR surface impoundments as proposed except 
for those that fall under the deferral of closure described above 
(i.e., units closed under State authority, units beneath critical 
infrastructure).
    As stated in Sec.  257.102(e), closure has been initiated once any 
steps necessary to implement the closure plan as described by Unit 
III.B.2.g.ii of this preamble have been taken, including submitting an 
application for any necessary State or agency permits or permit 
modifications and taking steps to comply with standards of any State or 
other agency that are a prerequisite to completing closure of a CCR 
unit.
(b) Preparation of a Written Closure Plan for Legacy CCR Surface 
Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments comply with the existing requirements of Sec.  257.102(b) 
requiring the preparation of a written closure plan no later than 12 
months after the effective date of the final rule.
    As mentioned above, overall commenters on the proposed rule agreed 
that closure requirements, including the written closure plan, would 
generally be appropriate for legacy CCR surface impoundments. One 
commenter suggested additional requirements for the content of the 
closure plan including the elevation of the base of the unit, 
groundwater information, and descriptions of compliance with Sec.  
257.102 will be achieved (e.g., how free liquids would be eliminated, 
how waste will be stabilized, measures to minimize the need for further 
maintenance of the CCR unit). A few commenters supported the proposed 
deadline but as summarized in Units III.B.2.a.ii and III.B.2.g of this 
preamble, other commenters stated the proposed deadline was infeasible 
and inappropriate. One commenter suggested the deadline for the closure 
plan be extended to be concurrent with the initiation of closure. 
Commenters suggestions for the deadline for the completion of the 
closure plan ranged from 12 (the 2015 CCR Rule deadline) to 32 months, 
or after the collection of the eight baseline groundwater samples.
    EPA disagrees with the commenter that additional requirements 
regarding the content of the closure plan are necessary. The 
information the commenter requested be included in the closure plan is 
1) already required to be in the closure plan pursuant to Sec. Sec.  
257.102(b) or 2) readily available in other required reports (e.g., the 
annual groundwater monitoring and corrective action reports). 
Furthermore, the commenter failed to fully explain how compliance with 
Sec.  257.102(b) does not provide the information needed to determine 
if compliance with the closure performance standards will be met.
    Regarding the deadline, as stated above, EPA concludes that the 
deadline for the closure plan should be extended from the proposed 
deadline to allow for owners or operators to incorporate information 
about groundwater quality, groundwater flows, seasonality impacts, and 
the migration of contaminants (if any) into the plan. Therefore, EPA is 
finalizing a deadline of no later than

[[Page 39033]]

Monday, November 8, 2027, which is 36 months after the effective date. 
This is codified in the regulatory text at Sec.  257.100(f)(5)(i).
    Based on comments on the proposed rule and experience from the 2015 
CCR Rule, EPA expects the incorporation of this information into the 
closure plan will allow facilities to select a closure method that most 
appropriately addresses issues like waste that is in contact with 
groundwater, groundwater contamination, and long-term structural 
stability concerns. Closure plans that adequately address these issues 
will result in more compliant closure plans and therefore, be more 
protective of human health and the environment.
    The closure plan describes the steps necessary to close a CCR unit 
at any point during the active life of the unit based on recognized and 
generally accepted good engineering practices. 40 CFR 257.102(b)(1). 
The plan must set out whether the closure of the CCR unit will be 
accomplished by leaving CCR in place or through closure by removal and 
include a written narrative describing how the unit will be closed in 
accordance with the section, or in other words, how the closure will 
meet all the performance standards in the regulations. 40 CFR 
257.102(b)(1)(i). The written closure plan must also provide a schedule 
for completing all activities necessary to satisfy the closure criteria 
of the rule. See also 80 FR 21410-21425.
    If the CCR is left in place, the closure plan must include a 
description of the final cover system and how the final cover system 
will achieve the regulatory performance standards. If the base of the 
impoundment intersects with groundwater, the closure plan would need to 
discuss the engineering measures taken to ensure that the groundwater 
had been removed from the unit prior to the start of installing the 
final cover system, as required by Sec.  257.102(d)(2)(i). The closure 
plan would also need to describe how the facility plans to meet the 
requirements in Sec.  257.102(d)(1) to ``control, minimize or 
eliminate, to the maximum extent feasible, post-closure infiltration of 
liquids into the waste and releases of CCR, leachate, or contaminated 
run-off to the ground or surface waters.'' This could include, for 
example, the installation of engineering controls that would address 
the post-closure infiltration of liquids into the waste from all 
directions, as well as any post-closure releases to the groundwater 
from the sides and bottom of the unit.
(c) Preparation of a Written Post-Closure Care Plan for Legacy CCR 
Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments would be required to comply with the existing requirement 
in Sec.  257.104(d) regarding the preparation of a written post-closure 
no later than 12 months after the effective date of the final rule.
    The comments EPA received on the proposed rule regarding the post-
closure plan requirement are described in Units III.B.2.g and 
III.B.2.g.i and can be summarized as requests for an extension of the 
post-closure care deadline to allow for a more feasible deadline and 
the incorporation of groundwater monitoring data. For the reasons 
stated in Units III.B.2.g and III.B.2.g.i, EPA is finalizing a deadline 
of no later than Monday, November 8, 2027, which is 36 months from the 
effective date of the final rule to comply with the post-closure care 
requirement in Sec.  257.104(d). This is codified in the regulatory 
text at Sec.  257.100(f)(5)(ii).
    Section 257.104(d) requires that an owner or operator of a CCR unit 
prepare a written post-closure plan. The contents of the P.E.-certified 
plan are stated in the rule at Sec.  257.104(d)(1)(i) through (iii) and 
can be summarized as a description of the monitoring and maintenance 
activities required for the unit, the frequency that these activities 
will be performed, information for the point-of-contact during the 
post-closure care period, and planned uses of the property.
(d) Deadline To Complete Closure for Legacy CCR Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundment comply with the existing closure completion time frames in 
Sec.  257.102(f).
    As stated in Unit III.B.2.g of this preamble, some commenters on 
the proposed rule supported the proposed deadline, however, overall 
commenters supported applying the existing closure completion time 
frames as long as the proposed deadline for the initiation of closure 
was extended. For the reasons described throughout this section, EPA 
has extended the deadline for the initiation of closure. EPA expects 
the extension to the deadlines for the closure plan and initiation of 
closure, as well as the options to defer closure requirements for 
legacy CCR surface impoundments that have completed closure under a 
regulatory authority (see Unit III.B.2.g.iii.b), to address the 
concerns commenters expressed with the infeasibility or 
inappropriateness of the deadline to complete closure. Therefore, EPA 
is finalizing the deadline for the completion of closure of legacy CCR 
surface impoundments as proposed.
    Section 257.102(f) generally requires an owner or operator of 
existing and new CCR surface impoundments to complete closure 
activities within five years from initiating closure. However, the 
regulations also establish conditions, including documentation 
requirements, under which owners or operators can demonstrate and 
receive two-year extensions of the deadline. For CCR surface 
impoundments of 40 acres or less, the deadline can only be extended by 
one two-year extension. For CCR surface impoundments larger than 40 
acres, the deadline can be extended in increments of two years for no 
more than five times.
(e) Post-Closure Care for Legacy CCR Surface Impoundments
    EPA proposed to apply the existing post-closure care requirements 
at Sec.  257.104 to legacy CCR surface impoundments without revision. 
These criteria are essential to ensuring the long-term safety of legacy 
CCR surface impoundments.
    No commenters raised specific concern about requiring legacy 
impoundments to comply with the existing requirements in Sec.  257.104. 
EPA is therefore finalizing this provision without revision.
    The existing post-closure care criteria require the monitoring and 
maintenance of units that have closed with CCR in place for at least 30 
years after closure has been completed. 40 CFR 257.104. During this 
post-closure period, the facility would be required to continue 
groundwater monitoring and corrective action, where necessary.
h. Recordkeeping, Notification, and Internet Posting Criteria for 
Legacy CCR Surface Impoundments
    EPA proposed that owners or operators of legacy CCR surface 
impoundments be subject to the existing recordkeeping, notification, 
and website reporting requirements in the CCR regulations found at 
Sec. Sec.  257.105 through 257.107. For reasons specified in the 2015 
CCR Rule, the CCR regulations require the owner or operator of a new or 
existing CCR unit to record specific information in the facility's 
operating record, maintain files of all required information (e.g., 
demonstrations, plans, notifications, reports) that supports 
implementation and compliance with the rule, notify State Director and 
Tribal authorities, and maintain a public CCR

[[Page 39034]]

website that hosts this information. 80 FR 21427.
    A commenter on the proposed rule supported applying recordkeeping, 
notification, and internet posting requirements to legacy CCR surface 
impoundments but stated that the existing requirements were ineffective 
at ensuring compliance with the CCR regulations or allowing for 
meaningful public awareness or participation. The commenter suggested 
that EPA create mechanisms within the rule to ensure the public has the 
opportunity to participate in the decision-making processes at 
regulated CCR units; standardize reporting to make the report more 
easily understood by the public; establish organizational requirements 
for the CCR websites; require public notice and engagement when 
notifying the State Director and/or appropriate Tribal authority as 
required by the CCR rule; extend the period of time the files required 
by the CCR rule must be maintained in the operating record; and require 
owners or operators to certify compliance documentation for the CCR 
units. This commenter also suggested EPA clarify what records owners or 
operators are required to retain and to publish.
    EPA agrees with the commenter on the importance of meaningful 
public participation. The current regulations allow for public 
participation by requiring owner or operators to hold a public meeting 
as part of the assessment of corrective measures in Sec.  257.96, 
creating a mechanism for the public to file dust complaints in Sec.  
257.80(b), and the ``contact us'' form or specific email address on 
facilities' public CCR websites for questions or issues from the public 
as required by Sec.  257.107(a). EPA does not have evidence to support 
the claim by the commenter that these opportunities for public 
participation are ineffective. Furthermore, EPA does not find other 
decision-making points in the rule appropriate for mandatory public 
meetings although facilities are encouraged to engage with the public 
and to both solicit and incorporate public input into decisions, such 
as closure methods, as able and appropriate.
    With respect to the commenter's suggestions that EPA require the 
owners or operators of CCR units to certify compliance documentation 
and create standardized reporting and website layout requirements, as 
explained in the proposed rule, EPA does not have evidence that legacy 
CCR surface impoundments are sufficiently different than currently 
regulated facilities to necessitate substantially different 
requirements. The commenter provided no factual basis to support the 
suggestion that requiring owner or operator certifications would 
improve compliance with the regulations beyond the certifications 
currently required by professional engineers. When justifying the 
request for standardized reporting and website layout requirements, the 
commenter failed to explain how compliance with the public website 
posting requirements in Sec.  257.107, including the requirement to 
ensure all information is ``clearly identifiable and must be able to be 
immediately printed and downloaded by anyone accessing the site'' is 
inadequate or a hinderance to the public accessing the required 
information. Therefore, EPA does not believe additional notification, 
certification, or public engagement requirements for legacy CCR surface 
impoundments would be appropriate.
    EPA agrees with the commenter on the need to extend the period of 
time files required by the CCR rule must be maintained on the 
facilities' public websites and in the operating records. As described 
in Unit III.D.5, EPA is extending how long files must be maintained in 
the operating record and on the public website. While EPA believes the 
regulations at Sec. Sec.  257.105 and 257.107 clearly lay out what 
records must be retained and published, EPA has included in Unit 
III.D.5 a table that details what records are required to be maintained 
in the operating record and on the public website as well as the 
corresponding retention periods.
    EPA is finalizing the requirement that owners or operators of 
legacy CCR surface impoundments comply with recordkeeping, 
notification, and internet posting requirements at Sec. Sec.  257.105 
through 257.107. Owners or operators must document implementation and 
compliance with the rule and must place these files into the facility's 
operating record. Each required file must be maintained in the 
operating record for the entirety of the retention period specified in 
Sec.  257.105 following submittal of the file into the operating 
record. Each file must also indicate the date the file was placed in 
the operating record. Files are required to be submitted into the 
operating record at the time the documentation becomes available or by 
the compliance deadline specified in the CCR regulations. Section 
257.105 contains a comprehensive listing of each recordkeeping 
requirement and corresponding record retention periods.
    Furthermore, the owner or operator of a legacy CCR surface 
impoundment must maintain a CCR website titled, ``CCR Rule Compliance 
Data and Information'' that hosts the compliance information so that it 
may be viewed by the public. Unless provided otherwise in the rule 
(see, Unit III.E.5), information posted to the publicly accessible 
internet site must be available for a period of no less than five years 
from the initial posting date for each submission. Posting of 
information must be completed no later than 30 days from the submittal 
of the information to the operating record. Owners or operators of 
legacy CCR surface impoundments have 30 days from the effective date of 
this rule to establish a CCR website and post the required applicable 
information.

C. CCR Management Unit Requirements

    EPA is establishing requirements to address the risks from 
previously unregulated solid waste management of CCR that involves the 
direct placement of CCR on the land at CCR facilities. Information 
obtained since 2015 demonstrates that these exempt solid waste 
management practices are currently contaminating groundwater at many 
sites, and at others, have the potential to pose risks commensurate 
with the risks associated with currently regulated activities.
    The closure of CCRMU of 1,000 tons or greater also provides 
significant risk mitigation. As laid out in Unit III.A of this 
preamble, CCRMU at both active facilities and inactive facilities with 
legacy impoundments pose risks to human health and the environment that 
are at least as significant as the risks presented by legacy CCR 
surface impoundments and the units currently regulated under the 2015 
CCR Rule. In particular, for highly exposed individuals off site, 
landfill CCRMU were estimated to pose cancer risks as high as 7 x 
10-\6\ from arsenic III, while surface impoundment CCRMU 
were estimated to pose cancer risks as high as 8 x 10-\5\ 
from arsenic III and noncancer HQs as high as 2 for arsenic III, two 
for lithium, and one for molybdenum. Differences in national risks 
between currently regulated units and these older units are attributed 
largely to the proportion of units that were modeled at the time as 
lined. However, the risks associated with these older units may be even 
higher than EPA modeled in the 2014 Risk Assessment for active units. 
These units have been present onsite longer and had more time to leak. 
In addition, there are several management practices that have the 
potential to result in higher leakage, but that were previously modeled 
either less frequently for active units--based on a belief that the 
practices had declined over time--or not at all--due to data 
constraints on a national scale. These include: (1) The greater 
prevalence of

[[Page 39035]]

unlined units; (2) The greater likelihood of co-management of CCR with 
coal refuse and other wastes in surface impoundments, making the 
overall waste pH far more acidic and (3) The potential for the units to 
be constructed below the water table or to have become inundated with 
groundwater after the time of construction. As discussed in Unit III.A, 
each of these practices individually have the potential to result in 
nationwide risks higher than previously reported on a national basis 
for the currently operating universe of CCR units. For example, unlined 
landfill CCRMU were estimated to pose cancer risks as high as 1 x 
10-\5\ from arsenic III, while unlined surface impoundment 
CCRMU were estimated to pose cancer risks ranging from 2 x 
10-\4\ from arsenic III and noncancer HQs as high as 5 for 
arsenic III, 3 for lithium, 2 for molybdenum, and 1 for thallium. A 
combination of these practices could push risks even higher than 
modeled.
    Based on these data, EPA is finalizing the addition of a new 
category of CCR units that would be subject to a set of requirements 
tailored to the characteristics of such units and the risks that they 
present. This new category of CCR units, called ``CCR management 
units'' or CCRMU, consists of CCR surface impoundments and landfills 
that were closed prior to the effective date of the 2015 CCR Rule, and 
inactive CCR landfills, which include inactive CCR piles. Under this 
final rule, CCR management units are subject to the regulations when 
they are located at: (1) A facility currently regulated under the 2015 
CCR Rule; (2) Inactive facilities with a legacy CCR surface 
impoundment; and (3) Facilities that, on or after October 19, 2015, 
produced electricity for the grid but were not regulated under the 2015 
CCR Rule because they had ceased placement of CCR in onsite CCR units 
and did not have an inactive CCR surface impoundment (the inclusion of 
these facilities are discussed in Unit III.C.2.f). EPA refers to the 
facilities in the above three categories in this preamble as ``covered 
CCR facilities.''
    Owners or operators of any of covered CCR facilities are required 
to conduct a facility evaluation to identify and delineate any CCRMU 
containing one ton (or more) at the facility and document the findings 
in two reports. In addition, owners or operators of a covered CCR 
facility are required to ensure that all identified CCRMU containing 
1,000 tons or more comply with the existing requirements in 40 CFR part 
257, subpart D for groundwater monitoring, corrective action (where 
necessary), and in certain cases, closure, and post-closure care 
requirements. These issues are discussed in more detail in this Unit of 
the preamble.
    EPA estimates that there are 179 CCRMU at 92 active facilities and 
16 CCRMU at 12 inactive facilities that will be subject to the 
requirements of this final rule.\64\ These areas include inactive CCR 
landfills, closed CCR landfills, closed CCR surface impoundments, and 
other solid waste management areas of CCR. EPA also identified 20 CCRMU 
at eight other active facilities. This estimate of CCRMU is an increase 
from the 134 CCRMU located at 82 facilities identified in the proposed 
rule. 88 FR 32028.
---------------------------------------------------------------------------

    \64\ An updated list of known potential CCRMU can be found in 
the docket for this action. See document titled ``Universe of CCR 
Management Units. April 2024.''
---------------------------------------------------------------------------

1. Damage Cases
    EPA has a long history of considering damage cases in its 
regulatory decisions under RCRA. RCRA specifically directs EPA, when 
making a Regulatory Determination for CCR, to consider ``documented 
cases in which danger to human health and the environment from surface 
run-off or leachate has been proved,'' demonstrating that such 
information is to carry great weight in decisions of whether and how to 
regulate such wastes. 42 U.S.C. 6982(n)(4). See also 42 U.S.C. 
6982(n)(3). In addition, damage cases are among the criteria EPA must 
consider under its regulations for determining whether to list a waste 
as a ``hazardous waste.'' See 40 CFR 261.11(a)(3)(ix). EPA also relied 
on damage cases to develop the specific requirements for CCR in part 
257, subpart D. See, 80 FR 21452-21459.
    Damage cases generally provide direct evidence of both the extent 
and nature of the potential risks to human health and the environment 
that have resulted from actual waste management practice. For example, 
in the 2015 CCR Rule, EPA relied on damage cases to identify actual 
management practices that resulted in harm above and beyond that 
already identified through modeling. Based on the damage cases, EPA 
identified several additional constituents (antimony, barium, 
beryllium, chromium, selenium, and lead) that were added to the 
Appendix IV list for groundwater monitoring.
    For CCRMU, EPA proposed to rely on ten potential damage cases to 
further support the results of the modeling and 2014 Risk Assessment, 
and to better understand the characteristics of the sites and units, as 
well as the management practices, in order to develop appropriate 
requirements. EPA reviewed information received in response to the 
ANPRM as well as the documents posted on facilities' CCR websites for 
compliance with CCR regulations. See, 88 FR 32012. Specifically, EPA 
reviewed groundwater monitoring reports, assessment of corrective 
measures reports, corrective measures progress reports, remedy 
selection reports, history of construction reports, closure plans and 
reports, and fugitive dust control plans for facilities with CCR 
websites from 2018, 2019, 2020, and 2021. Through review of the 
groundwater monitoring and corrective action reports, EPA found many 
instances where the owners or operators of CCR facilities claimed that 
the detection of an SSI or SSL in concentrations of Appendix III or IV 
constituents in groundwater came from a CCRMU rather than the monitored 
regulated CCR unit.
    Whenever a facility determines that there is an SSI over background 
levels for one or more of the constituents in Appendix III at a 
monitoring well at the downgradient waste boundary, the existing CCR 
regulations allow the facility an opportunity to complete an ASD 
showing that a source other than the unit (i.e., an alternative source) 
was the cause of the SSI. 40 CFR 257.94(e)(2). The existing CCR 
regulations provide a similar opportunity whenever assessment 
monitoring results indicate that an SSL exceeding the GWPS has been 
detected at a downgradient well for any of the Appendix IV 
constituents. 40 CFR 257.95(g)(3). If a successful ASD for an SSL is 
not completed within 90 days, corrective action must be initiated.
    In reviewing groundwater monitoring and corrective action reports 
EPA found that 42 ASDs or ACMs concluded that a Federally unregulated 
CCR source was responsible for the SSI or SSL. The proposed rule 
included ten examples (i.e., damage cases) where owners or operators of 
CCR facilities claimed that an SSI or SSL is attributable to a CCR 
source rather than the Federally regulated CCR unit.
    In addition to reviewing the groundwater monitoring and corrective 
action reports, EPA reviewed the history of construction reports, 
closure plans and reports, and fugitive dust control plans for 
facilities with CCR websites from 2018, 2019, 2020, and 2021. These 
documents contained either site maps, which identified currently 
regulated units, and in some cases, inactive or closed units at the 
facility, or narrative discussions of the site history, which included 
identification of where CCR

[[Page 39036]]

were previously disposed or managed at the facility.
    EPA received numerous comments about the damage cases provided in 
the proposed rule. Some commenters provided information to demonstrate 
that many of EPA's listed damage cases did not meet EPA's criteria for 
a damage case to be considered ``a proven damage case,'' that had been 
developed for purposes of the Bevill Regulatory Determinations 
described in 65 FR 32214, 32224 (May 22, 2000). One commenter 
mischaracterized these criteria as ``EPA's criteria for identifying 
damage cases in RCRA rulemakings,'' and claimed that groundwater 
exceedances are not sufficient to prove that there is any risk to human 
health. The commenter stated that ``exceedances [must be] measured in 
ground water at a sufficient distance from the waste management unit to 
indicate that hazardous constituents had migrated to the extent that 
they could cause human health concerns'' citing the 2000 Regulatory 
Determination (65 FR 32224, May 22, 2000), and the 2010 proposed CCR 
Rule (75 FR 35131, June 21, 2010). The commenter asserted that without 
such information, none of the cases can be used to justify EPA's 
proposed regulation of CCR management units.
    Another commenter argued that ``the damage cases are not 
representative of all CCRMUs, and, consequently, cannot legitimately be 
relied upon to develop national standards and requirements for all 
CCRMUs.'' The commenter claims that a report generated by Gradient 
documents ``many examples of CCRMUs that are not causing any GWPS 
exceedances, are not associated with any undue risk, and are being 
effectively regulated under state purview.'' Additionally, the 
commenter claims that the ``damage cases cited by US EPA do not 
demonstrate that CCRMUs are currently impacting groundwater quality and 
causing an unacceptable risk because EPA has not addressed whether the 
groundwater impacts that they have attributed to CCRMUs result from the 
current condition of each CCRMU or its historical operating 
condition.'' The commenter concludes that because EPA has provided no 
evidence to determine whether the impacts are being caused by the 
current condition of each CCRMU (potentially closed, inactive, and/or 
dewatered), EPA's conclusions that the damage cases provide evidence of 
potential risks associated with CCRMU is misguided and unsupported.
    One commenter also took issue with EPA's inclusion of ``only'' ten 
``hand-picked'' damage cases to justify regulation of CCRMU. The 
commenter complained that ``EPA's damage cases are not based on 
information collected by EPA, but rather are based on information 
compiled by advocacy groups using data collected from CCR websites, 
[and t]here is no indication EPA has conducted its own data collection, 
or verified the data that was collected.'' The commenter went on to 
say,

    Much of the data refers to alternative source analyses conducted 
for regulated CCR units, suggesting that the discussed `CCRMU' may 
be the source of groundwater contamination; however, EPA makes no 
statements regarding whether, and conducts no analysis to determine 
whether, it agrees with those analyses. This is highlighted by the 
carefulness of EPA's declaration that its review of the third-party 
compiled information identified 42 areas ``potentially contaminating 
groundwater.'' . Potential groundwater impacts does not rise to the 
RCRA protectiveness level of ``reasonable probability of adverse 
effects on health or the environment from disposal of solid waste at 
such facility.

    Finally, one commenter complained that of the 134 areas EPA 
identified where the management of CCR remain exempt, less than one 
third were found to potentially have groundwater impacts, yet EPA seeks 
to regulate the entire universe of 134 areas and more. According to 
this commenter, even assuming the potential groundwater impacts are 
real, they are not necessarily an indication that the CCR management 
practice creates a reasonable probability of an adverse effect on human 
health or the environment, as the commenter believes there are several 
other factors, such as the nature and extent of the CCR management 
practice, whether a hydraulic head is present, the hydraulic 
conductivity of surrounding soils, and the proximity of the material to 
water and the likelihood of contact with water, that must be considered 
before concluding a CCR management practice creates a reasonable 
probability of an adverse effect.
    EPA disagrees that it is inappropriate to characterize the cited 
SSIs and SSLs as damage cases. As explained in the 2015 CCR Rule 
preamble, EPA has a long history of considering damage cases in its 
regulatory decisions under RCRA. 80 FR 21452. The statute specifically 
directs EPA to consider ``documented cases in which danger to human 
health and the environment from surface runoff or leachate has been 
proved,'' in reaching its Regulatory Determination for these wastes, 
demonstrating that such information is to carry great weight in 
determining whether to regulate these wastes. 42 U.S.C. 6982(n)(4). 
Damage cases, even if only potential damage cases, are also relevant 
under the third Bevill factor: ``potential danger, if any, to human 
health and the environment from the disposal and reuse of such 
materials.'' 42 U.S.C. 6982(n)(4). In addition, damage cases are among 
the criteria EPA must consider under its regulations for determining 
whether to list a waste as a ``hazardous waste.'' See 40 CFR 
261.11(a)(3)(ix). Damage cases generally provide extremely potent 
evidence in hazardous waste listings.
    As with the 2015 CCR Rule, EPA considers that both proven and 
potential damage cases provide information directly relevant to this 
rulemaking. Damage cases--whether proven or potential--provide evidence 
of both the extent and nature of the potential risks to human health 
and the environment. The primary difference between a proven and a 
potential damage case is whether the contamination has migrated off-
site of the facility. But the mere fact that groundwater contamination 
has not yet migrated off-site does not change the fact that a 
potentially harmful constituent has leached from the unit into 
groundwater. Whether the constituent ultimately causes further damage 
by migrating into drinking water wells does not diminish the 
significance of the environmental damage caused to the groundwater 
under the site, even where it is only a future source of drinking 
water. As explained in the original 1979 subtitle D criteria, EPA is 
concerned with groundwater contamination even if the aquifer is not 
currently used as a source of drinking water. Sources of drinking water 
are finite, and future users' interests must also be protected. (See 44 
FR 53445-53448.) (``The Act and its legislative history clearly reflect 
Congressional intent that protection of groundwater is to be a prime 
concern of the criterion. . . . EPA believes that solid waste 
activities should not be allowed to contaminate underground drinking 
water sources to exceed established drinking water standards. Future 
users of the aquifer will not be protected unless such an approach is 
taken.''). EPA is therefore presenting its findings with regard to 
damage cases because this information further supports the results of 
EPA's 2014 and 2024 Risk Assessments, which together provide the 
factual bases for the actions taken in this final rule.
    EPA also disagrees with the arguments that attempt to minimize the 
significance of the damage case record. EPA is relying on the damage 
cases to evaluate the extent and nature of the risks associated with 
particular CCR management practices. Facts

[[Page 39037]]

demonstrating the consequences from particular activities therefore 
remain relevant, particularly (although not solely) where the 
management practices continue to occur. In other words, what matters in 
this regard are facts that provide information on the reasons that unit 
leaked, the particular contaminants that were present, the levels of 
those contaminants, and the nature of any impacts caused by that 
contamination. This is entirely consistent with RCRA section 8002(n), 
which requires EPA to evaluate the ``potential danger, if any, to human 
health and the environment from the disposal and reuse of such 
materials'' in addition to ``documented'' damage cases. 42 U.S.C. 
6982(n)(3)-(4).
    EPA further disagrees that only the presence of receptors within 
the impact sphere of a contaminating facility merits consideration of a 
particular damage case. EPA's longstanding and consistent policy across 
numerous regulatory programs has been that groundwater contamination is 
a significant concern that merits regulatory action in its own right, 
whether or not the aquifer is currently used as a source of drinking 
water. Sources of drinking water are finite, and future users' 
interests must also be protected. The absence of current receptors is 
therefore also not an appropriate basis on which to discount damage 
cases. And for all the reasons discussed above, EPA also disagrees that 
only exceedances of health-based standards of contaminants that have 
migrated off-site (i.e., only proven damage cases) should be accounted 
for as part of this rulemaking.
    EPA further disagrees with commenters' assertions about the sources 
of information that EPA included in the proposed rule and that EPA is 
relying upon in this final rule. In the proposal EPA discussed 
information that the Agency obtained from comments submitted in 
response to the ANPRM, and from other sources provided by environmental 
groups. However, EPA conducted an independent review of information 
posted on facility websites, including groundwater monitoring reports, 
assessment of corrective measures reports, corrective measures progress 
reports, remedy selection reports, history of construction reports, 
closure plans and reports, and fugitive dust control plans for 
facilities with CCR websites from 2018, 2019, 2020, and 2021 to develop 
the record for the proposed rule. 88 FR 32012-32013.
    Several commenters disagreed with EPA's characterization in the 
proposed rule of certain sites as damage cases because the units have 
now been closed or the contamination has been remediated (or is in the 
process of being remediated) under State oversight. For example, one 
commenter noted that they are ``aware of situations where over the 
years CCR was intermittently dispersed within fill to facilitate 
facility expansions (commonly referred to as ``made land''), which was 
a common practice along heavily industrialized shores of the Great 
Lakes.'' The commenter further stated that, the ``Phases I and II of 
the Landfill at NIPSCO's R.M. Schahfer Generating Station, is an 
example of how the Proposed Rule mischaracterizes the risk associated 
with CCRMU.'' According to the commenter Phases I and II have been 
closed in a manner that is protective of groundwater, and the data 
demonstrates that the groundwater plume resulting from Phases I and II 
is stable, with concentrations of constituents declining.
    Another commenter similarly objected to EPA's inclusion of Reid 
Gardner as an example of CCRMU with identified SSIs. The commenter said 
EPA mistakenly assumed the historical ponds under the regulated units 
may be a cause of SSIs. They said these historical ponds were excavated 
and removed prior to 2015 so these units cannot be deemed to be a 
CCRMU. As a result, they said EPA's characterization of Reid Gardner as 
a damage case is inaccurate and inappropriate and should be removed 
from the final rule. In addition, they disagreed with EPA's reliance on 
``standard GWPS'' equivalent to MCLs, stating that by doing so, EPA 
fails to consider site-specific factors such as pre-existing 
groundwater contamination, natural variation in groundwater, and the 
site conceptual model, as well as EPA guidance for statistical 
analysis. Finally, the commenter said that corrective actions at Reid 
Gardner are comprehensively regulated under the State, which governs 
the performance and/or completion of Environmental Contaminant 
characterization, the screening and selection of Corrective Action, and 
the implementation and long-term Operation and Maintenance of [NDEP] 
approved Corrective Action concerning Pollution Conditions at the Site 
(Nevada Division of Environmental Protection Administrative Order on 
Consent Reid Gardner Generating Station, I.4, page 2). According to the 
commenter, interim corrective actions completed under the 
Administrative Order have already resulted in the removal of over 2.5 
million cubic yards of CCR and associated materials from the site.
    The same commenter also disagreed with EPA's inclusion of 
Huntington as an example of a CCRMU with identified SSLs. They said 
EPA's statement that the plant's remedy selection report ``does not 
appear to address releases from the Old Landfill,'' is incorrect, as 
the selected remedy--a groundwater capture system--has been placed to 
capture groundwater from both the regulated landfill and the Old 
Landfill. In addition, the commenter said the Old Landfill is subject 
to separate State oversight and corrective action, including 
elimination of infiltration, capping of closed sections and capture of 
any seepage. As a result, they disagreed with EPA's characterization of 
Huntington as a damage case and stated it should be removed from the 
final rule.
    One commenter claimed that the damage case example concerning East 
Kentucky Power Cooperative's Cooper Station does not support the 
conclusion EPA draws from it. Specifically, EPA's proposal refers to a 
former surface impoundment below the current landfill at the facility, 
but, as the proposal recognizes, the facility conducted an ASD that did 
not identify the former impoundment as an alternate source of 
groundwater impact and the unit therefore remains in detection 
monitoring, with no conclusion having been drawn. As such, the 
commenter said, ``EPA is relying on an ASD which did not identify the 
impoundment as an alternative source to justify more stringent 
regulation of CCRMU with respect to groundwater impacts that have not 
been found to have resulted from the unit.'' EPA agrees that this 
facility should not be included in the final list of damage case 
examples based on this comment.
    Other commenters provided information about EPA's Damage Case 
Compendiums developed for the 2015 CCR Rule to show some of those 
include potential CCRMU. They also provided additional damage cases and 
lists of potential CCRMU for EPA to include in the record.
    Except as noted above, EPA disagrees that the damage cases are not 
representative of CCRMU, even if the units are regulated under State 
programs. The data from these units shows these CCRMU are contributing 
to groundwater contamination, irrespective of any prior State 
oversight.
    EPA also continues to believe that, as EPA explained in the 2015 
CCR Rule, cases where contamination has been remediated remain relevant 
to this rulemaking. EPA is relying on the damage cases to evaluate the 
extent and nature of the risks associated with particular CCR 
management practices.

[[Page 39038]]

Facts demonstrating the consequences from particular activities 
therefore remain relevant, particularly (although not solely) where the 
management practices continue to occur. In other words, what matters in 
this regard are facts that provide information on the reasons that unit 
leaked, the particular contaminants that were present, the levels of 
those contaminants, and the nature of any impacts caused by that 
contamination. None of these facts are affected by whether the damage 
is ultimately mitigated or remedied. This is entirely consistent with 
RCRA section 8002(n), which requires EPA to evaluate the ``potential 
danger, if any, to human health and the environment from the disposal 
and reuse of such materials'' in addition to ``documented'' damage 
cases. 42 U.S.C. 6982(n)(3)-(4). Accordingly, the fact that any 
contamination has subsequently been remediated is not a basis for 
disregarding a damage case. See 80 FR 21455.
    In summary, EPA continues to believe the damage cases provide 
extremely valuable evidence that is directly relevant to the question 
of whether and how to regulate CCR. For example, the damage cases 
provide ``real world'' evidence against which to compare EPA's risk 
modeling estimates, such as evidence regarding the frequency with which 
particular constituents leach into groundwater. 80 FR 21326. They also 
provide direct evidence regarding specific waste management practices 
at electric utilities, along with the potential consequences of those 
practices. Accordingly, EPA has sufficient confidence in the veracity 
of the collected information to rely on it in making decisions in this 
rule. EPA expects that additional damage cases will be discovered in 
response to the installation of the groundwater monitoring systems 
required by the final rule.
a. Examples of CCRMU With Identified SSLs
    Under the existing CCR regulations, when a facility determines 
there is an SSL for one or more Appendix IV constituents and completes 
a successful ASD showing that a source other than the regulated unit is 
the cause of the SSL(s), the facility is not required to initiate 
corrective action for that particular constituent. Through reviewing 
the ASD posted on facility websites, EPA identified several areas at 
active facilities where CCR is managed outside of a regulated unit and 
is identified as a source of one or more Appendix IV SSL(s). The 
following facilities are examples of situations in which such areas 
have been identified as the source of an SSL and therefore support 
EPA's determination that such areas warrant regulation under RCRA 
section 4004(a).
James H Campbell Power Plant, West Olive, Michigan
    The JH Campbell Power Plant, owned and operated by Consumers Energy 
Company, is located within a mile of Lake Michigan. The facility has 
five regulated CCR units, including three CCR surface impoundments 
(Pond A, Bottom Ash Ponds 1-2, and Bottom Ash Pond 3) and two CCR 
landfills. The ``wet ash ponds area'' is approximately 267 acres and is 
bounded by perimeter dikes with a system of internal dikes separating 
the individual ash ponds. In addition to the five regulated CCR units, 
there are at least seven other unregulated, unlined ``closed'' 
impoundments \65\ that ceased placement of waste prior to October 19, 
2015, do not have an engineered cap nor vegetative cap, and have a 
closure plan that was approved by the State. Based on the groundwater 
monitoring report reviews, there were SSIs over background at many 
wells at all units and some had an SSL for arsenic and selenium. At 
Pond A, which closed with waste in place in 2019, there are SSIs for 
boron and sulfate, and SSLs were identified for arsenic (13 [micro]g/L 
[MCL of 10 [micro]g/L]) and selenium \66\ (143 [micro]g/L [MCL of 50 
[micro]g/L]) for which an assessment of corrective measures was 
completed, and the selected remedy is source removal and final cover as 
the primary corrective action. In the 2021 Annual Groundwater 
Monitoring and Corrective Action Report posted in January 2022, 
Consumers Energy concluded there was an ASD for Pond A and said, 
``Increases in Appendix III constituents (e.g. boron) and direct 
exceedances of the selenium GWPS in JHC-MW-15011, JHC-MW-15010, JHC-MW-
15009, and JHC-MW-15008R that have not yet resulted in a statistically 
significant exceedance suggest a detectable influence from the 
immediately adjacent, upgradient, closed, pre-existing CCR units on-
site. The closed, preexisting units are not regulated under the RCRA 
CCR Rule, but remedial action is being taken under Consent Agreement 
WMRPD No. 115-01-2018. A [remedial action plan] for these units was 
submitted to [Michigan's Department of Environment, Great Lakes, and 
Energy] on September 30, 2021.'' During the 2021 groundwater monitoring 
period for Bottom Ash Ponds 1-2, which closed by removal in 2018, SSIs 
were identified for boron, calcium, chloride, pH, sulfate, and total 
dissolved solids (TDS); also, one SSL was identified for arsenic (38 
[micro]g/L [MCL of 10 [micro]g/L]).\67\ An assessment of corrective 
measures has been completed for the CCR unit and the primary selected 
remedy is source removal and final cover. Consumers Energy also said in 
the 2022 semiannual progress report that the facility is reevaluating 
the groundwater ``monitoring system for [Bottom Ash] Ponds 1-2 to more 
accurately account for the influence from the closed, pre-existing 
units.''
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    \65\ These ``closed'' impoundments (Pond B, Pond C, Pond D, Pond 
F, Pond G (G1 and G2), Pond H, and Pond K) are listed in a figure on 
page 12 of the 2021 Annual Groundwater Monitoring and Corrective 
Action Report, JH Campbell Power Plant Pond A, January 2022, 
Prepared for Consumer's Energy.
    \66\ JH Campbell Semiannual Progress Report--Selection of 
Remedy, Ponds 1-2 North and 1-2 South, and Pond A, July 30, 2022. 
Pages 3-4.
    \67\ Annual Groundwater Monitoring and Corrective Action Report, 
JH Campbell Power Plant Ponds 1-2 North and 1-2 South, January 2022, 
Prepared for Consumers Energy. Page 23.
---------------------------------------------------------------------------

New Castle Generating Station, Pennsylvania
    GenOn Power Midwest LP (GenOn) operates the New Castle Generating 
Station located in West Pittsburg, Pennsylvania. The New Castle 
Generating Station has two CCR units subject to the regulations--an 
impoundment (North Bottom Ash Pond) and a landfill (New Castle Plant 
Ash Landfill). Each of these CCR units has relevance to this proposal 
due to other unregulated disposal units located adjacent to the 
regulated CCR units.
    The North Bottom Ash Pond was used for the management of bottom ash 
until 2016 when the facility transitioned from coal to natural gas. 
After the transition to natural gas, GenOn initiated closure of the 
North Bottom Ash Pond by removing all waste from the impoundment. 
Closure of the impoundment was certified in 2019.\68\ Groundwater 
monitoring associated with the impoundment while the unit was operating 
detected arsenic at SSL above the GWPS in all downgradient monitoring 
wells.\69\ In accordance with the procedures in the regulations for CCR 
units in 40 CFR 257.94(e)(2), GenOn determined that an alternative 
source was responsible for these SSLs of arsenic. Specifically, the ASD 
found that a 120-acre unlined CCR surface impoundment located 
immediately adjacent to the North Bottom Ash Pond

[[Page 39039]]

was responsible for the arsenic concentrations in the downgradient 
monitoring wells.\70\ According to the 2019 Annual Report prepared by 
GenOn, there were SSLs for arsenic (0.087 mg/L [MCL of 10 [micro]g/L]) 
in the downgradient monitoring wells.\71\ Consequently, because the 
SSLs of arsenic were attributed to another source (i.e., a former 
unlined CCR surface impoundment), GenOn concluded it was not required 
to remediate the arsenic contamination under the Federal CCR 
regulations.
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    \68\ CCR Compliance, Closure Certification Report, Closure by 
Removal, New Castle North Bottom Ash Pond. June 2019.
    \69\ Id. At 5.
    \70\ Id.
    \71\ CCR Compliance, Groundwater Monitoring and Corrective 
Action Annual Report, New Castle North Ash Pond and Ash Landfill. 
January 2020.
---------------------------------------------------------------------------

    GenOn also determined that there were SSIs above background levels 
for multiple analytes at the New Castle Plant Ash Landfill (Ash 
Landfill), which is the other regulated CCR unit at the New Castle 
Generating Station. In its most recent annual groundwater monitoring 
report in 2022, GenOn reported SSIs for boron, calcium, fluoride, 
sulfate, and total dissolved solids.\72\ GenOn determined that an 
alternative source was responsible for these analyte increases, 
specifically pointing to an ``underlying historic ash impoundment and 
other closed stages of the landfill.'' \73\ Prior to development of the 
60-acre Ash Landfill, CCR was disposed in an impoundment from 
approximately 1939 to 1978.\74\ After the impoundment was dewatered in 
1978, dry CCR was disposed in this area in several stages of CCR 
placement up until the time Ash Landfill began operation. Since 2018, 
GenOn has attributed SSIs for boron, calcium, fluoride, sulfate, and 
TDS to this historic disposal of CCR.
---------------------------------------------------------------------------

    \72\ CCR Compliance, Groundwater Monitoring and Corrective 
Action Annual Report, New Castle Ash Landfill. December 2022.
    \73\ Id. At 3.
    \74\ New Castle Plant Ash Landfill--Annual CCR Unit Inspection 
Report. January 16, 2018.
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Huntington Power Plant, Utah
    The Huntington Power Plant in Huntington, Utah is owned and 
operated by PacifiCorp and has one regulated unit, the Huntington CCR 
Landfill. While conducting the required groundwater monitoring for the 
Huntington CCR Landfill, there were SSLs for chromium, cobalt, lithium, 
molybdenum, selenium, fluoride, and arsenic, so the owner or operator 
conducted assessment of corrective measures. There is also a former 
combustion waste landfill called the Old Landfill, which is located 
northwest of the regulated Huntington CCR Landfill. The ACM report \75\ 
assumes the SSLs are the result of groundwater interactions with both 
the Huntington CCR Landfill and the Old Landfill. Both landfills have 
stormwater run-on from the area surrounding the landfill. This run-on 
is routed around the landfills via diversion ditches and run-off from 
the landfills itself is collected and retained in a sediment basin 
north of the Huntington CCR Landfill. The facility is implementing a 
remedy to address releases only from the regulated CCR Huntington 
Landfill, but the remedy selection report \76\ does not appear to 
address releases from the Old Landfill.
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    \75\ Corrective Measures Assessment CCR Landfill--Huntington 
Power Plant Huntington, Utah. May 2019.
    \76\ Remedy Selection Report CCR Landfill--Huntington Power 
Plant, Huntington, Utah. August 2020.
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J.B. Sims, Grand Haven, Michigan
    The J.B. Sims Generating Station, owned and operated by Grand Haven 
Board of Light and Power, is located on Harbor Island, north of Grand 
Haven, Michigan. Harbor Island is bound to the north, east, and west by 
the Grand River and to the south by the South Channel, tributaries of 
Lake Michigan. The facility has two Federally regulated CCR units (Unit 
1 & 2 and Unit 3), both of which are inactive, unlined surface 
impoundments. Unit 1 & 2 is approximately 1.2 acres and includes areas 
where, prior to October 19, 2015, CCR was placed in unlined 
impoundments and used as fill in low-lying areas of adjacent wetlands. 
Unit 3 is approximately 0.5 acres and was built on top of historically 
placed CCR. The boundary of Unit 1 & 2 was updated in an agreement with 
EPA and the State in January 2021,\77\ to include an area that received 
CCR prior to 1978. Therefore, the groundwater monitoring network and 
closure plan are currently being updated to reflect the new boundary 
and better address contamination from historical CCR across the 
units.\78\ Additionally, in March 2022, the State issued an enforcement 
notice \79\ to J.B. Sims citing inadequate groundwater monitoring and 
failure to address all areas where CCR were managed (e.g., stored, 
placed) prior to disposal during the unit's operation. As such, the 
facility is considering expanding Unit 3's groundwater monitoring 
network. The units are often partially flooded, and groundwater 
elevations and flow direction are influenced by precipitation and water 
levels in the Grand River and the South Channel.
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    \77\ The meeting between Grand Haven Board of Light and Power, 
the State, and EPA during which the new boundaries for Unit 1 & 2 
were agreed to is discussed on page 3 (PDF page 10) of the 2021 
Annual Groundwater Monitoring & Corrective Action Report by Golder 
Associates. January 28, 2022.
    \78\ Letter to Grand Haven Board of Light and Power-Update To 
The October 14, 2019 J.B. Sims Generating Station Inactive Units \1/
2\ Impoundment And Unit 3 Closure Plan--Interim Conditions For 
Closure. October 22, 2021.
    \79\ The State of Michigan, Department of Environment, Great 
Lakes, and Energy (EGLE) issued an enforcement notice via email 
March 22, 2022, to Grand Haven Board of Light and Power, J.B. Sims.
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    Based on groundwater monitoring report reviews, both units have had 
SSIs and SSLs since groundwater monitoring was initiated in 2017. 
During 2021, both Unit 1 & 2 and Unit 3 had SSIs for all Appendix III 
constituents and SSLs for arsenic (98 [micro]g/L [MCL is 10 [micro]g/
L]), chromium (270 [micro]g/L [MCL is 100 [micro]g/L]), cobalt (22 
[micro]g/L [GWPS is 6 [micro]g/L], fluoride (13 mg/L [MCL is 4 mg/L]), 
and lithium (2800 [micro]g/L [site-specific GWPS is 59 [micro]g/
L]).\80\ In December 2020, J.B. Sims submitted an ASD for Unit 3's 2019 
SSLs for chromium, cobalt, fluoride, lead, and lithium, pointing to the 
historic fill across the island as the source of the SSLs. 
81 82 Furthermore, the Fourth Quarterly 2021 Monitoring 
Report suggested the continued SSIs and SSLs at Unit 3 were due to 
historical CCR fill beneath the unit, historical fill outside of Unit 1 
& 2, and waste historically placed across the site.\83\ However, until 
the groundwater monitoring networks are finalized, the extent of 
groundwater contamination and the source of all contamination cannot be 
determined. The assessment of corrective measures for both units began 
in February 2019 and is ongoing, pending finalization of the 
groundwater monitoring networks. Based on groundwater monitoring 
reports, EPA has found that due to the fluctuations in groundwater 
elevations in response to precipitation and nearby surface water 
levels, portions of the facility, including Unit 1 & 2, can be 
inundated or partially in contact with groundwater.
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    \80\ SSL concentrations can be found in Appendix B (PDF page 
512) of the 2021 Groundwater Monitoring & Corrective Action Report 
prepared by Golder Associates on behalf of Grand Haven.
    \81\ 2020 Alternate Source Demonstration J.B. Sims Generating 
Station--Unit 3 Impoundments Submitted to: Grand Haven Board of 
Light and Power Submitted by Golder Associates Inc. December 28, 
2020.
    \82\ Technical Memorandum to Michigan Department of Environment, 
Great Lakes, and Energy-Unit 3 Impoundments Alternate Source 
Demonstration Response Grand Haven Board Of Light And Power--JB Sims 
Power Generating Station. February 12, 2020.
    \83\ Memorandum to Michigan Department of Environment, Great 
Lakes, and Energy- Fourth Quarter 2021 Monitoring Report, Former JB 
Sims Generating Station, Unit 3 A&B Impoundments--Response to 
Comments. March 8, 2022.

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[[Page 39040]]

b. Examples of CCRMU With Identified SSIs
    Under the existing CCR regulations, when a facility determines 
there is an SSI for one or more Appendix III constituents and completes 
a successful ASD showing that a source other than the regulated unit is 
the cause of the SSI(s), the facility is not required to initiate 
assessment monitoring for that particular constituent. 40 CFR 
257.94(e). Through ASD reviews, EPA identified several areas at active 
facilities where CCR was managed outside of a regulated unit and was 
identified as a source of one or more Appendix III SSI(s). As such, any 
groundwater contamination from these potential CCRMU have not been 
investigated under the existing Federal CCR regulations. The following 
facilities are examples of situations in which potential CCRMU have 
been identified as the source of an SSI and demonstrate the need to 
regulate CCRMU.
Reid Gardner Generating Station, Moapa Valley, Nevada
    Reid Gardner Generating Station (Reid Gardner), owned and operated 
by NV Energy, is located adjacent to the Muddy River and the Moapa Band 
of Paiutes reservation, approximately 45 miles northeast of Las Vegas. 
Reid Gardner has seven regulated CCR units: four unlined inactive 
surface impoundments (Pond 4B-1, Pond 4B-2, Pond 4B-3, and Pond E-1), 
two active unlined surface impoundments (Pond M-5 and Pond M-7), and 
one partially lined landfill (Mesa Landfill). The inactive surface 
impoundments covered 47 acres and were closed by removal in 2017.\84\ 
The inactive surface impoundments were constructed in 2003 (Pond E-1) 
and 2006 (Pond 4B-1, Pond 4B-2, and Pond 4B-3) to replace four of the 
eleven historical unlined evaporation ponds located at the facility 
that made up the evaporation pond complex (Pond 4A, Pond 4B-1, Pond 4B-
2, Pond 4B-3, Pond 4C-1, Pond 4C-2, Pond D, Pond E-1, Pond E-2, Pond F, 
and Pond G).\85\ The evaporation pond complex was built within the 
Muddy River floodplain and used from approximately 1974 until 
approximately 2002 to evaporate CCR and other process wastewaters from 
the facility. The two active surface impoundments (Ponds M-5 and M-7) 
were constructed in 2010 approximately 0.75 miles south of the 
historical evaporation ponds and cover 28 acres. Mesa Landfill was 
constructed and operational prior to the 2015 CCR Rule and has a 
surface area of roughly 252 acres.
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    \84\ Reid Gardner Generating Station Inactive Coal Combustion 
Residual Surface Impoundments Ponds 4B-1, 4B-2, 4B-3, and E-1 
Closure Certification, April 2019.
    \85\ Construction History, Pond E1, Reid Gardner Generating 
Station. April 11, 2018.
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    Based on groundwater monitoring report reviews, the inactive 
surface impoundments had no Appendix III SSIs above their established 
background concentrations during the detection monitoring event in 
2019.86 87 88 89 90 91 However, the inactive surface 
impoundments did have Appendix IV constituent concentrations above the 
standard GWPS, including arsenic (2.52 mg/L [MCL is 0.01 mg/L]), 
cadmium (0.0072 mg/L [MCL is 0.005 mg/L]), cobalt (242 [micro]g/L 
[standard GWPS is 6 [micro]g/L]), fluoride (35.4 mg/L [MCL is 4.0 mg/
L]), lithium (27,300 [micro]g/L [standard GWPS is 40 [micro]g/L]), 
molybdenum (6,390 [micro]g/L [standard GWPS is 100 [micro]g/L]), 
selenium (0.204 mg/L [MCL is 0.05 mg/L]), thallium (0.026 mg/L [MCL is 
0.002 mg/L]), and radium 226 & 228 combined (8.02 pCi/L [MCL is 5 pCi/
L]). Ponds M-5 and M-7 and the Mesa Landfill have had SSIs for fluoride 
every year of detection monitoring for which ASDs have been performed 
pointing to natural variation in groundwater 
quality.92 93 94 95 96 97 ASDs were also performed for SSIs 
at Mesa Landfill for pH (2019 and 2021) and turbidity (2020 and 2021) 
that attributed the SSIs to natural variation in groundwater quality. 
Therefore, since ASDs have been performed for all SSIs and the active 
units, Reid Gardner has not moved from detection monitoring to 
assessment monitoring. The facility also claims the historical, co-
located evaporation ponds are the source of groundwater contamination 
in the area and not the CCR-regulated units. Specifically, in the 
closure certification for the inactive surface impoundments, the 
facility points to documentation as far back as the 1980s that describe 
seepage from Pond D, the historical Pond E-1 and E-2, Pond F, and Pond 
G and leakage at an estimated rate of 50 acre-feet/year from Ponds 4C-1 
and 4C-2 and historical Ponds 4B-1, 4B-2, and 4B-3.
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    \86\ Reid Gardner Generating Station Inactive CCR Surface 
Impoundment E-1. Coal Combustion Residual 209 Annual Groundwater 
Monitoring and Corrective Action Report. July 31, 2019.
    \87\ Reid Gardner Generating Station Inactive CCR Surface 
Impoundments 4B-1, 4B-2, and 4B-3. Coal Combustion Residual 2019 
Annual Groundwater Monitoring and Corrective Action Report. Revision 
1. May 14, 2020.
    \88\ Reid Gardner Generating Station Mesa Impoundments M5 and M7 
Coal Combustion Residual 2019 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
31, 2020.
    \89\ Reid Gardner Generating Station Mesa Impoundments M5 and M7 
Coal Combustion Residual 2020 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
29, 2021.
    \90\ Reid Gardner Generating Station Mesa Impoundments M5 and M7 
Coal Combustion Residual 2021 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
28, 2022.
    \91\ Alternate Source Demonstration and Addendum to the Coal 
Combustion Residual 2017 Annual Groundwater Monitoring and 
Corrective Action Report Reid Gardner Generating Station Mesa CCR 
Surface Impoundments (Ponds M5 and M7). Prepared for NV Energy. 
April 13, 2018.
    \92\ Reid Gardner Generating Station Mesa Landfill Coal 
Combustion Residual 2018 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
31, 2019.
    \93\ Reid Gardner Generating Station Mesa Impoundments M5 and M7 
Coal Combustion Residual 2018 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
31, 2019.
    \94\ Reid Gardner Generating Station Mesa Landfill Coal 
Combustion Residual 2019 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
31, 2020.
    \95\ Reid Gardner Generating Station Mesa Landfill Coal 
Combustion Residual 2020 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
31, 2021.
    \96\ Reid Gardner Generating Station Mesa Landfill Coal 
Combustion Residual 2021 Annual Groundwater Monitoring and 
Corrective Action Report and Alternate Source Demonstration. January 
28, 2022.
    \97\ Alternate Source Demonstration and Addendum to the Coal 
Combustion Residual 2017 Annual Groundwater Monitoring and 
Corrective Action Report Reid Gardner Generating Station Mesa 
Landfill. Prepared for NV Energy. April 13, 2018
---------------------------------------------------------------------------

Seminole Electric Cooperative, Florida
    Seminole Electric Cooperative (Seminole) operates the Seminole 
Generating Station located in Palatka, Florida. For CCR that is not 
beneficially used, CCR is disposed at the facility in a landfill 
(Increment One Landfill), which is subject to the CCR regulations. This 
CCR landfill is a double-lined landfill with a leachate collection 
system and, because part of the Increment One Landfill overlaps with 
the side-slope of a former, Federally unregulated landfill, the liner 
system also includes a high-density polyethylene geomembrane where the 
two units interface.\98\ Seminole determined there were SSIs above 
background levels for multiple analytes in one or more monitoring wells 
at the downgradient waste boundary in 2018, including SSIs for boron, 
calcium, chloride, sulfate, and TDS. Seminole determined that one or 
more alternative sources were responsible for these analyte increases. 
These sources include

[[Page 39041]]

former test cells (i.e., areas where CCR was placed in the 1980s for 
purposes of construction evaluations that are now located beneath the 
Increment One Landfill), a former CCR landfill adjacent to the 
Increment One Landfill, and several process water ponds next to the 
Increment One Landfill.\99\ Since 2018, Seminole has attributed SSIs 
for these analytes to these alternative sources and therefore, has not 
moved from detection monitoring to assessment monitoring.
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    \98\ Seminole Generating Station Increment One Landfill Annual 
Groundwater Monitoring and Corrective Action Report. January 31, 
2019.
    \99\ Id. at 20.
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R.M. Schahfer Generating Station, Indiana
    The R.M. Schahfer Generating Station, owned and operated by 
Northern Indiana Public Service Company, LLC (NIPSCO), has several CCR 
units subject to the regulations, including several CCR impoundments 
and a CCR landfill consisting of multiple cells or phases of operation 
(``Landfill''). The Landfill is of particular relevance to this 
proposal because includes three cells subject to Federal CCR 
regulations (Phases V through VII) and four landfill cells that are not 
(Phases I through IV). In the course of conducting the required 
groundwater monitoring for the regulated cells of the Landfill, in 
January 2018, NIPSCO determined that there were SSIs above background 
levels for all seven analytes in Appendix III at one or more monitoring 
wells at the downgradient waste boundary of the regulated CCR units. 
This included SSIs for boron, calcium, chloride, fluoride, pH, sulfate, 
and TDS.\100\ Through procedures laid out in the regulations for 
regulated CCR units in 40 CFR 257.94(e)(2), NIPSCO determined that 
these groundwater SSI impacts were not due to a release from the 
regulated CCR landfill cells, but instead were attributable to another 
source. Specifically, NIPSCO has concluded that ``a release from the 
non-regulated, unlined portions of the landfill, Phases 1 and II, is 
the source of the identified SSIs.'' \101\ Subsequent groundwater 
monitoring of the regulated Landfill cells since 2018 continues to 
identify SSIs and NIPSCO continues to attribute those impacts to 
releases from the unregulated Phase I and II cells.\102\
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    \100\ 2018 Annual Groundwater Monitoring and Corrective Action 
Report--Landfill Phase V and Phase VI, NIPSCO R.M. Schahfer 
Generating Station. January 31, 2019.
    \101\ Northern Indiana Public Service Company, R.M. Schahfer 
Generating Station, Wheatfield, Indiana, Schahfer Landfill Phase V 
and Phase VI, Alternative Source Demonstration. April 13, 2018. 
Begins on PDF page 20 of the 2018 Annual Groundwater Monitoring and 
Corrective Action Report--Landfill Phase V and Phase VI. April 13, 
2018.
    \102\ 2021 Annual Groundwater Monitoring and Corrective Action 
Report, Landfill Phase V, Phase VI, and Phase VII, NIPSCO LLC R.M. 
Schahfer Generating Station. January 31, 2022.
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    Landfill Phase I is a 20-acre unlined cell that received CCR (flue 
gas desulfurization materials and fly ash) between 1984 and 1991 and 
subsequently closed with a final cover system in 1999. Phase II of the 
Landfill is an unlined 42-acre cell where flue gas desulfurization 
materials and fly ash were disposed between 1991 to 1998. The Phase II 
cell was closed with a final cover system in 1998. CCR landfills such 
as the Phase I and II cells are not regulated by the existing 
regulations because the cells have not received CCR on or after October 
19, 2015. As a result, NIPSCO has not been required under the existing 
Federal CCR regulations to investigate further and remediate as 
necessary groundwater impacts from the unlined Phase I and II cells.
Waukegan Generating Station, Illinois
    An example of CCR used as fill on-site is Midwest Generation's 
Waukegan Generating Station in Waukegan, Illinois. There are two CCR 
surface impoundments named the East Ash Pond and West Ash Pond, which 
were used interchangeably during the facility's operational history and 
have a multi-unit groundwater monitoring system. The East Ash Pond has 
a surface area of 9.8 acres with a storage capacity of 184,000 cubic 
yards. The West Ash Pond has a surface area of 10 acres with a storage 
capacity of 223,000 cubic yards. According to the 2018 Annual 
Groundwater Monitoring and Corrective Action Report, there was 
detection of SSIs over background for Appendix III constituents, 
including pH and sulfate.\103\ An ASD was completed that claimed other 
potential historic sources were the cause of the SSIs. In the 2019 
Annual Groundwater Monitoring and Corrective Action Report, an ASD for 
Appendix III constituents identified calcium and TDS with the same 
claim that other potential historic sources were the cause of the 
SSIs.\104\ The ASDs discuss that the downgradient monitoring wells were 
installed within the berms for the surface impoundments that consisted 
of a ``mixture of fill and beneficially reused coal combustion by-
product''.105 106 The 2018 ASD also notes that a upgradient 
well, MW-05 which is not a part of the CCR groundwater monitoring 
network, has substantially higher sulfate and boron concentrations than 
the downgradient wells suggesting an upgradient source. Furthermore, 
the 2019 ASD mentions that the fluctuating TDS concentrations at 
downgradient well MW-16 are correlated to fluctuations in TDS at MW-05 
further suggesting an upgradient source. While these ASDs suggest that 
the sources may be CCR within the berms and a upgradient source they do 
not analyze these potential sources to verify the claims. EPA did 
verify that the boring logs for groundwater monitoring wells MW-01 
through MW-05 and MW-16 show they were installed within 11 to 20 feet 
of CCR in the berms surrounding the surface impoundments.\107\ In 
addition, construction drawings in the history of construction show 
``existing fill'' or CCR was used in the construction of the surface 
impoundment access ramps and underneath the surface impoundments 
liners.\108\ The facility continued to use the ASDs for SSIs in 2020 
and 2021, therefore, the surface impoundments remain in detection 
monitoring.
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    \103\ 2018 Waukegan Generating Station Annual GWMCA Report, 
Appendix B, PDF pg. 100. January 2019.
    \104\ 2019 Waukegan Generating Station Annual GWMCA Report, 
Appendix B, PDF pg. 100. January 2020.
    \105\ 2020 Waukegan Generating Station Annual GWMCA Report. 
January 2021.
    \106\ 2021 Waukegan Generating Station Annual GWMCA Report. 
January 2022.
    \107\ Waukegan boring well logs.
    \108\ October 2016, Waukegan Generating Station History of 
Construction.
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White Bluff Steam Electric Station, Arkansas
    The White Bluff Steam Electric Station in Redfield, Arkansas is 
owned or operated by Entergy and has three CCR units: two CCR surface 
impoundments (A Recycle Pond/South Pond and B Recycle Pond/North Pond); 
and one CCR landfill (Existing CCR Landfill Cells 1-4). CCR previously 
was disposed in a 20-acre ravine,\109\ which was closed and covered in 
accordance with the original facility State-issued permit. The active 
landfill was then built on top of, and adjacent to, the unlined, closed 
landfill. In 2018, the facility conducted intrawell monitoring of the 
groundwater at the facility and SSIs for pH, calcium, TDS, and boron 
were detected. An ASD was completed and determined that the sources of 
the SSIs were: (1) Releases from portions of the Coal Ash Disposal 
Landfill (CADL) closed before the effective date of the CCR Rule 
(October 19, 2015); (2) Surface water that has come into contact with 
on[hyphen]site CCR and has migrated into the subsurface; and/or (3) 
Natural variation

[[Page 39042]]

in groundwater quality. Therefore, the landfill remains in detection 
monitoring.
---------------------------------------------------------------------------

    \109\ Entergy Arkansas, LLC White Bluff Steam Electric Station 
Landfill Cells 1-4 2021 Annual Groundwater Monitoring and Corrective 
Action Report. January 31, 2022.
---------------------------------------------------------------------------

c. Examples of CCRMU With Identified SSIs or SSLs From Comments
    EPA received several comments about potential damage cases from 
CCRMU. In addition, many comments provided additional potential CCRMU 
but evidence of a thorough groundwater quality investigation in this 
area was not presented. If there are monitoring wells at the facility, 
the wells are not sufficient to characterize groundwater impacts from 
the CCRMU. Therefore, due to lack of data, EPA and the commenters could 
not definitively determine if certain unregulated placement of CCR at 
facilities is a CCRMU or if the CCRMU could be potential damage cases. 
EPA presents the following additional examples of CCRMU that have 
adequate groundwater monitoring to show impacts.
Brandywine Ash Management Facility, Maryland
    The Brandywine Ash Management Facility in Prince George's County, 
Maryland has a 217-acre CCR landfill. It is operated by GenOn MD Ash 
Management, LLC. CCR has been landfilled at the facility since 
approximately 1971. As of 2018, an estimated 6.8 million cubic yards, 
or 7 billion kilograms, of CCR were placed at the site. CCR at 
Brandywine has contaminated groundwater and surface water, leading to 
legal action by the State of Maryland. A 2013 Consent Decree resulted 
in the development of a Corrective Measures Plan and a Nature and 
Extent of Contamination Study.110 111 According to the 
Consent Decree, ``The original design of the disposal cells and 
operation of the disposal areas. . .has resulted in some leachate 
escaping the disposal cells via groundwater and constructed outfalls 
and entering surface waters . . .'' \112\
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    \110\ Consent Decree, State of Maryland et. al v. Genon MD Ash 
Management, LLC (No. 8:12-cv-03755-PJM, D. Md., May 1, 2013).
    \111\ Id.
    \112\ Id.
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    ``Based on a review of the quarterly Discharge Monitoring Reports . 
. . and other quarterly and annual monitoring reports submitted by 
GenOn, [Maryland Department of the Environment (MDE)] has determined 
that wastewater discharges from monitoring points at Brandywine have at 
times exceeded ambient surface water quality standards for cadmium and/
or selenium. MDE has also determined that leachate has entered 
groundwater and is causing the [maximum contaminant level (MCL)] for 
cadmium to be exceeded at times at certain groundwater monitoring 
points, as were federally recommended secondary standards for 
manganese, sulfate, iron, [total dissolved solids (TDS)], aluminum and 
chloride.'' \113\
---------------------------------------------------------------------------

    \113\ Geosyntec Consultants. 2018. 2017 Annual Groundwater 
Monitoring And Corrective Action Report, Brandywine Ash Management 
Facility Phase II, Brandywine, Maryland. Prepared for GenOn MD Ash 
Management. January.
---------------------------------------------------------------------------

    This broader context related to State law--which is absent from 
documents submitted pursuant to the 2015 CCR Rule--is important for 
understanding the complexity of the Brandywine site and its impacts. 
For example, unsafe lithium levels hundreds of times higher than the 
default GWPS in the 2015 CCR Rule have been documented at groundwater 
monitoring wells, as have unsafe molybdenum levels up to approximately 
80 times higher than its default GWPS. Some of these unsafe levels are 
found in monitoring wells not included in the network used to 
demonstrate compliance with the Federal CCR Rule.\114\
---------------------------------------------------------------------------

    \114\ Earthjustice et al. Legacy Proposal Comment Appendix VI. 
EPA-HQ-OLEM-2020-0107-0368.
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    The Brandywine site includes four areas of interest: Historical 
Area 1, Historical Area 2, Phase I, and Phase II.115 116 
Because these four areas are all part of a single landfill and in some 
cases overlap, they should have all been subject to the 2015 CCR Rule--
even though three of the areas were closed before the rule took effect. 
In its filings to comply with the 2015 CCR Rule, GenOn has treated the 
Historical Area 1, Historical Area 2, and Phase I areas as unregulated 
units and has pointed to these areas as the source of pollution in its 
ASDs. For this reason, the site has remained in detection monitoring 
through at least 2021.\117\
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    \115\ Geosyntec Consultants. 2018. Nature and Extent of 
Contamination Study, Final Report, Brandywine Ash Management 
Facility, Brandywine, Maryland. Prepared for GenOn MD Ash 
Management. June.
    \116\ Geosyntec Consultants. 2018. Corrective Measures Plan, 
Brandywine Ash Management Facility, Brandywine, Maryland. Prepared 
for GenOn MD Ash Management. June.
    \117\ Geosyntec Consultants. 2022. 2021 Annual Groundwater 
Monitoring and Corrective Action Report, Federal CCR Rule, 
Brandywine Ash Management Facility, Phase II, Brandywine, Maryland. 
Prepared for GenOn MD Ash Management. January.
---------------------------------------------------------------------------

Bull Run Fossil Plant, Tennessee
    The Bull Run Fossil Plant is owned and operated by Tennessee Valley 
Authority (TVA) in Clinton, Tennessee and has two unregulated CCR 
landfills. Groundwater monitoring results show the landfills have been 
leaching arsenic, boron, cobalt, manganese, and molybdenum into the 
groundwater for decades, resulting in groundwater that exceeds health 
standards for these toxins by many times. In addition, a portion of one 
of the landfills, the Dry Fly Ash Stack, is not regulated by the 2015 
CCR Rule as it ceased receipt of CCR in 2015 an interim soil cover was 
placed on Phase 2, and in accordance with a permit issued by the 
Tennessee Department of Environment and Conservation, it will be closed 
in conjunction with the currently operating Dry Fly Ash Stack Lateral 
Expansion.\118\ Among other things, the 2023 Bull Run Environmental 
Assessment Report states that the Dry Fly Ash Stack contains 3.7 
million cubic yards of coal ash, and shows that lithium and molybdenum 
in downgradient groundwater exceed groundwater screening levels by at 
least an order of magnitude.\119\
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    \118\ Tennessee Valley Authority. Bull Run Environmental 
Assessment Report. Appendix D-CCR Management Unit Cross Sections. 
August 2023.
    \119\ Tennessee Valley Authority. Bull Run Environmental 
Assessment Report. Bull Run Fossil Plant, Clinton, Tennessee. August 
2023.
---------------------------------------------------------------------------

Hennepin Power Station, Illinois
    The Hennepin Power Station in Hennepin, Illinois has five CCR units 
including four CCR surface impoundments (Ash Pond No. 2, East Ash Pond, 
Old West Ash Pond, and Old West Polishing Pond) and one CCR landfill 
(CCR Landfill). The East Ash Pond System includes Ash Pond No. 2, the 
East Ash Pond, and Ash Pond No. 4, which were built on top of historic 
CCR fill.\120\ Ash Pond No. 4 was a 30-foot-deep gravel quarry where 
coal ash fill was disposed in the mid-1980s.\121\ Groundwater 
downgradient of the East Ash Pond System, showed concentrations of 
sulfate and boron that exceeded State groundwater standards.\122\ The 
groundwater was (and may still be) contaminated with coal ash 
constituents.\123\
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    \120\ U.S. EPA, Damage Case Compendium, Technical Support 
Document, Vol. IIa: Potential Damage Cases (Reassessed, Formerly 
Published), Docket ID EPA-HQ-RCRA-2009-0640-12119 (Dec. 18, 2014) at 
30, ns.110.
    \121\ Id at 30.
    \122\ Id at 30.
    \123\ Id at 30.
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Will County Station, Illinois
    The Will County Station in Romeoville, Illinois is owned and 
operated by Midwest Generation Co. The facility has two CCR surface 
impoundments, Ash Pond 2S and Ash Pond 3S. Ash Ponds 1N and 1S were 
removed from service in 2010, and although they were not actively used 
for

[[Page 39043]]

waste storage, they still contained at least one inch of water in 2019 
and the base of these unlined impoundments are in contact with at least 
one foot of groundwater.\124\ In addition, through borings taken at the 
facility, historical CCR has been buried around the ash ponds, and the 
Former Slag and Bottom Ash Placement Area has been identified at the 
southeast corner of the station's boundary.
---------------------------------------------------------------------------

    \124\ Interim Opinion and Order, Sierra Club et al vs. Midwest 
Generation, LLC, Illinois Pollution Control Board, June 20, 2019.
---------------------------------------------------------------------------

    When constructing the groundwater monitoring system in 2010 and 
2011, well borings also showed a thick layer of CCR buried along the 
eastern edge of the four ash ponds. MW-1, MW-2, MW-3, MW-4, and MW-6 
show layers of fill between five and twelve feet thick containing 
CCR.\125\ Historical topographic maps and aerial imagery document ponds 
extending from north of Pond 1N to close to the southern property 
boundary. These historical waste storage areas would have surrounded 
the current regulated ponds and the area where CCR has been found 
buried near the ponds. The topographic map and aerial imagery from 1962 
show a large pond extending from north of Pond 1N to the southern 
property boundary. In 1973, waste storage areas are present in the 
vicinity of Ponds 2S and 3S and extend to the southern property 
boundary. By 1980, waste areas are depicted south of Pond 3S and 
surrounding Pond 1N. The series of unregulated ponds near the southern 
property boundary south of Pond 3S are visible on available maps until 
present day.126 127
---------------------------------------------------------------------------

    \125\ Id.
    \126\ Earthjustice et al. Legacy Proposal Comment Appendix VI. 
EPA-HQ-OLEM-2020-0107-0368.
    \127\ Earthjustice Appendix II. Examples of historical satellite 
imagery and topographic maps are included in Figure 23, Figure 24, 
and Figure 25. EPA-HQ-OLEM-2020-0107-0368.
---------------------------------------------------------------------------

    Historical ash in fill near the ponds is in contact with 
groundwater. Groundwater elevations fluctuate between 579 and 584 feet 
above mean sea level in this area. CCR is buried at elevations as low 
as 578.6 feet above mean sea level. MW-2 provides an example of ash in 
contact with groundwater. The boring log completed during its 
installation shows CCR down to 578.6 feet above mean sea level and the 
groundwater elevation was at 580.6 feet above mean sea level, meaning 
that at least two feet of groundwater was in contact with CCR at that 
time. Groundwater measurements at this well commonly range from 582 to 
584 feet, meaning three to five feet of CCR are routinely saturated 
with groundwater near MW-2.\128\
---------------------------------------------------------------------------

    \128\ Interim Opinion and Order, Sierra Club et al vs. Midwest 
Generation, LLC, Illinois Pollution Control Board, June 20, 2019.
---------------------------------------------------------------------------

    The Former Slag and Bottom Ash Placement Area is located at the 
southeast corner of the Will County site. A Phase II Environmental Site 
Assessment completed in 1998 identified this location as an ash 
disposal area. Borings revealed coal ash mixed with gravel up to three 
feet below the ground surface.\129\
---------------------------------------------------------------------------

    \129\ Id.
---------------------------------------------------------------------------

    Groundwater monitoring completed under the 2015 CCR Rule also 
demonstrates groundwater contamination at Will County. SSIs for 
chloride, fluoride, and TDS have been identified since the inception of 
the monitoring program in 2017 and in 2022, SSLs for arsenic and 
selenium were detected.\130\
---------------------------------------------------------------------------

    \130\ Earthjustice et al. Legacy Proposal Comment Appendix VI. 
EPA-HQ-OLEM-2020-0107-0368.
---------------------------------------------------------------------------

    While the regulated ponds are likely contributing to groundwater 
contamination, historical ash at the station is also a likely culprit. 
Historical ash along the eastern boundary of the four ponds is not 
capped or lined and is thus exposed to precipitation and groundwater. 
The regulated and unregulated ponds are unlined and are in contact with 
groundwater, making these units potential sources of groundwater 
contamination. Groundwater contamination increases as it passes 
through/under the ponds. Boron and sulfate concentrations doubled 
between well MW-1 upgradient of Pond 1N and MW-7 downgradient of the 
pond in monitoring data collected between 2010 and 2018.\131\
---------------------------------------------------------------------------

    \131\ Earthjustice et al. Legacy Proposal Comment Appendix VI. 
EPA-HQ-OLEM-2020-0107-0368.
---------------------------------------------------------------------------

    ASDs also provide evidence of a contaminant source other than the 
regulated ponds. An ASD completed in 2018 following SSIs for chloride, 
fluoride, and TDS at the regulated units concluded that the SSIs were 
from ``other potential sources'' and not from the regulated units.\132\
---------------------------------------------------------------------------

    \132\ Id.
---------------------------------------------------------------------------

    Groundwater monitoring during 2022 identified SSIs for boron, 
calcium, chloride, fluoride, and TDS across the monitoring network. 
SSLs for selenium at one well and arsenic at two wells were also 
identified and resulted in initiation of an ACM for the site. Notably, 
the two upgradient monitoring wells are contaminated. MW-06 had an SSI 
for calcium and an SSI for boron and SSL for selenium were detected at 
MW-05. These two upgradient wells are located along the eastern edge of 
the ponds in the area known to contain buried ash. SSIs and SSLs in 
downgradient wells indicate that the regulated ponds may also be 
contributing to groundwater contamination.\133\
---------------------------------------------------------------------------

    \133\ Id.
---------------------------------------------------------------------------

    The ASD completed following identification of SSLs at regulated 
Pond 2S and 3S determined that Pond 3S is likely contributing to 
groundwater contamination. The ASD reported statistically significant 
decreasing trends in chloride concentrations in both upgradient 
monitoring wells and statistically significant increasing trends in 
chloride concentrations in MW-09 and MW-11, both of which are 
immediately downgradient of Pond 2S.\134\
---------------------------------------------------------------------------

    \134\ Id.
---------------------------------------------------------------------------

    The prevailing groundwater flow at the site is from the east to the 
west across the ponds. Because historical ash is present along the 
eastern boundary of the ponds, the current monitoring network is not 
capable of accurately measuring groundwater contamination from each 
potential source. Further, all the wells designated upgradient are 
within the likely footprint of the historical CCR disposal area 
described above. Thus, none of the wells can assess upgradient 
groundwater quality accurately.
EPA Impoundment Assessments
    Commenters provided additional reviews of EPA's impoundment 
assessment reports that were conducted in 2011-2013. During the 
impoundment assessments, EPA documented eight power plants with 
historical ponds where coal dams were constructed in whole or part of 
coal ash.\135\ These plants include six plants on EPA's list of 
potential legacy CCR surface impoundments: Glen Lyn (VA), Hutsonville 
(IL), Jefferies (SC), Muskigum River (OH), Philip Sporn (WV), and 
Tanners Creek (IN). At two additional plants where historical ponds are 
identified, Cape Fear (NC) and Frank E. Ratts (IN), EPA also found coal 
ash used in the construction of the dams. The commenters included these 
plants as additional potential CCRMU.
---------------------------------------------------------------------------

    \135\ EPA, Coal Combustion Residuals Impoundment Assessment 
Reports (2014), https://www.epa.gov/sites/default/files/2016-06/documents/ccr_impoundmnt_asesmnt_rprts.pdf.
---------------------------------------------------------------------------

2. Applicability and Definitions Related to CCR Management Units
    EPA is finalizing new definitions and revising several existing 
definitions necessary to implement the new requirements for CCRMU. 
Specifically,

[[Page 39044]]

the final rule establishes new definitions for ``CCR management unit,'' 
``Contains CCR and liquids,'' ``Inactive CCR landfill,'' ``Liquids,'' 
and ``Regulated CCR unit'' and revises existing definitions for ``CCR 
landfill or landfill,'' ``CCR unit,'' ``Operator,'' ``Owner,'' and 
``State Director.'' Some of these definitions are discussed elsewhere 
in the preamble.
    EPA is also revising Sec.  257.50(d) to specify that part 257, 
subpart D applies to CCRMU of 1,000 tons or greater, located at 
facilities with a regulated CCR unit or active facilities without a 
regulated CCR unit. That provision also applies to CCRMU greater than 
or equal to one ton and less than 1,000 tons, located at active 
facilities or facilities legacy CCR surface impoundment are only 
subject to the requirements of the FER in Sec.  257.75 until a 
permitting authority determines that regulation of these units, either 
individually or in the aggregate, is warranted and determines the 
applicable requirements. Under the 2015 CCR Rule, Sec.  257.50(d) 
exempted from regulation those CCR landfills that had ceased receiving 
CCR prior to October 19, 2015. This action amends the exemption 
included in the 2015 CCR Rule.
    The sections below briefly explain what EPA proposed, summarize the 
public comments received, and provide the Agency's responses. The 
Agency addresses new and revised definitions in the following order: 
(1) CCR management unit; (2) CCR unit; (3) Owner and operator; and (4) 
Conforming revisions to other existing definitions.
a. Definition of CCR Management Unit
    EPA proposed to define a CCR management unit or CCRMU to capture 
the solid waste management practices that have been demonstrated in the 
2014 and 2024 Risk Assessments and the damage cases to have the 
potential to contaminate groundwater. EPA proposed to define a CCRMU as 
any area of land on which any non-containerized accumulations of CCR 
are received, placed, or otherwise managed, that is not a CCR unit. EPA 
explained in the proposed rule that the definition of a CCRMU is based 
on the current definitions of a CCR pile--which is currently regulated 
as a CCR landfill under part 257, subpart D--and of a CCR surface 
impoundment, which both rely on the concept of ``accumulations of 
CCR.'' See, 40 CFR 257.53 and 88 FR 32018.
    EPA proposed that CCRMU would include historical solid waste 
management units such as CCR landfills and surface impoundments that 
closed prior to the effective date of the 2015 CCR Rule (October 19, 
2015), as well as inactive CCR landfills (including abandoned piles). 
The proposal stated that a CCRMU would also include any other areas 
where the solid waste management of CCR on the ground has occurred, 
such as structural fill sites, CCR placed below currently regulated CCR 
units, evaporation ponds, or secondary or tertiary finishing ponds that 
have not been properly cleaned up, and haul roads made of CCR if the 
use does not meet the definition of beneficial use in Sec.  257.53. EPA 
explained that all of these examples involved the direct placement of 
CCR on the land, in sufficient quantities to raise concern about 
releases of hazardous constituents, and--in most, if not all cases--
with no measures in place to effectively limit the contact between the 
CCR and liquids, and subsequent generation and release of any leachate.
    EPA acknowledged that the proposed definition was broad, but the 
Agency did not intend that the placement of any amount of CCR would 
necessarily constitute a CCRMU. Accordingly, EPA proposed that the 
following would not be considered CCRMU: consistent with the current 
regulations, closed or inactive process water ponds, cooling water 
ponds, wastewater treatment ponds, and stormwater holding ponds or 
aeration ponds. EPA explained that these units are not designed to hold 
an accumulation of CCR, and in fact, do not generally contain a 
significant amount of CCR. See, 80 FR 21357. EPA also explained, 
consistent with the existing regulations, neither an area or unit at 
which exclusively non-CCR waste is managed, nor any containerized CCR, 
such as a silo, would be considered CCRMU because neither of these 
units present conditions that give rise to the risks modeled in EPA's 
assessment or identified in the damage cases. See, Id. at 21356.
    For similar reasons, the Agency proposed that any CCR used in 
roadbed and associated embankments would not be considered CCRMU. As 
EPA explained in the 2015 rule the methods of application are 
sufficiently different from CCR landfills that EPA cannot extrapolate 
from the available risk information to determine whether these 
activities present similar risks. Roadways are subject to engineering 
specifications that generally specify CCR to be placed in a thin layer 
(e.g., six to 12 inches) under a road. The placement under the surface 
of the road limits the degree to which rainwater can influence the 
leaching of the CCR. There are also significant differences between the 
manner in which roadways and landfills can potentially impact 
groundwater, such as the nature of mixing in the media and the leaching 
patterns. First, CCR landfills are typically a homogenously mixed 
system, and as a result, there are no spatial variations of the 
chemical and physical properties of the media (e.g., bulk density, 
hydraulic conductivity and contaminant concentration). By contrast, 
roadways are generally constructed of several layers with different 
material properties (heterogeneity). This difference affects the 
hydraulic conductivity of a mass of CCR in a landfill, as compared to 
CCR placed in an embankment. Any potential leaching will tend to spread 
over the length of the embankment, as opposed to the leaching in a 
downward motion that would occur in a homogenously filled landfill. 
Finally, EPA is concerned that groundwater monitoring of a road may not 
be practicable. However, even though EPA considers that the available 
information does not demonstrate that use in roadbed present sufficient 
risk to warrant the suite of requirements applicable to CCRMU, that 
calculus changes in the event the CCR in roadbed is contaminating 
groundwater. Accordingly, EPA proposed that if a facility subsequently 
determines that the CCR in onsite roadbed is contributing to 
contamination to the aquifer, the facility would be required to address 
the contamination. For example, if during an ongoing corrective action, 
a facility identifies the roadbed as an additional source of 
contamination, it would be required to address that contamination as 
part of the ongoing remediation of the aquifer. In addition, the 
measures EPA proposed to require facilities to take would not be 
expected to identify truly de minimis quantities of CCR. As discussed 
in greater detail in the next section, EPA proposed that facilities 
would only be required to identify accumulations if records confirm the 
existence of the CCRMU or visual evidence of CCR placement on the 
ground.
    In addition, EPA proposed to define the term inactive CCR landfill 
to mean an area of land or an excavation that contains CCR but that no 
longer receives CCR on or after the effective date of this final rule 
and that is not a surface impoundment, an underground injection well, a 
salt dome formation, a salt bed formation, an underground or surface 
coal mine or a cave. For purposes of this subpart, this term also 
includes sand and gravel pits that received CCR and abandoned CCR 
piles.

[[Page 39045]]

i. RCRA Authority
    Some commenters contended that West Virginia v. EPA, 142 S. Ct. 
2587, 2609 (2022) requires EPA to have clear congressional 
authorization to regulate CCRMU, and that Congress has not provided EPA 
with such authorization under either RCRA sections 4004(a) or 4005(d). 
The commenters are incorrect. All of the requirements adopted in this 
rulemaking to regulate CCRMU fall squarely within the authority 
Congress delegated to the Agency in RCRA sections 1008(a)(3), 4004(a), 
and 4005(d). Commenters' arguments to the contrary are based 
misunderstandings of the statutory structure and EPA's historical 
practice. The rule does not expand the scope of CCR regulation beyond 
what Congress envisioned. Further, in large part, commenters' arguments 
are premised on aspects of the proposal which have been revised in this 
final action in response to comments. Although the revisions were not 
necessary under West Virginia v. EPA (because EPA's exercise of 
authority through this rule does not implicate a major question), the 
revisions resolve many of the commenters' objections based on their 
view of the major questions doctrine. EPA addresses the comments in 
turn.
    Some commenters based their claim that the regulation of CCRMU 
presents a major question on the assertion that the proposal would 
regulate an undefinable number of past CCR management and disposal 
practices, ``irrespective of risk, location, or even whether such past 
activities have been (or are currently being) addressed by state 
governments or by EPA itself under other federal authorities.'' These 
commenters claimed that the proposal has no bounds.

    Just as an example, the Proposal would require operating power 
generation facilities to identify every CCRMU within its boundaries, 
even if located under existing structures critical to a plant's 
energy production operations, and to ``close,'' and in many cases 
reclose, those CCRMUs under the CCR rule's closure provisions. The 
Proposal blithely ignores whether in fact such requirements could be 
met, the associated costs, and the resulting interruption to power 
generation activities that could be incurred in attempting to meet 
these requirements.

    These commenters also note that Congress's failure to include the 
same authority for corrective action applicable to permitted hazardous 
waste sites found in section 3004(u) under subtitle D demonstrates that 
EPA lacks the authority to require CCRMU to comply with the part 257 
corrective action and closure requirements.
    Another commenter argued that the proposal ``would impermissibly 
expand EPA's role in the Subtitle D statutory regime beyond the limited 
role that Congress envisioned for the Agency'' based on their belief 
that the Congressional intent behind the WIIN Act was ``to restore the 
States to their historical, congressionally-intended lead role under 
RCRA Subtitle D in the implementation and enforcement of solid waste 
management programs.'' According to this commenter,

[w]hether or not EPA should have such a ``central role'' in the 
regulation of CCR under RCRA Subtitle D--one that would allow the 
Agency to assert federal jurisdiction over any area of land in any 
state simply because the land was, at any time, used to manage any 
non-containerized accumulation of CCR, regardless of whether the 
land has been and is in compliance with applicable state 
regulations--is a major policy question of significant national 
economic and political magnitude that Congress has not clearly 
delegated EPA the authority to address. . . At its core, EPA's 
delegated RCRA Subtitle D authority entails only the authority to 
promulgate guidelines and criteria, to be implemented by the States, 
to prohibit open dumping and to ensure that units are classified as 
sanitary landfills ``only if there is no reasonable probability of 
adverse effects on health or the environment from disposal of solid 
wastes at such facility. EPA's Proposal construes ``open dumps'' and 
``sanitary landfills'' to now include historically state-regulated 
solid waste management and resource conservation and recovery 
practices that Congress never intended (clearly or otherwise) for 
the Agency to regulate federally, as most recently evidenced by 
Congress's definition of a ``sanitary landfill'' in the WIIN Act as 
a CCR unit that complies with a state CCR permit, or a federal CCR 
permit in a nonparticipating state, or the requirements of the CCR 
Rule applicable to CCR units in the absence of a federal CCR 
permitting program.

    This commenter stated that the WIIN Act limited the reach of EPA's 
authority to `` `CCR units,' as defined in the 2015 CCR Rule, i.e., to 
`any CCR landfill, CCR surface impoundment, or lateral expansion of a 
CCR unit, or a combination of more than one of these.' '' In addition, 
the commenter argued that EPA lacks the authority to now regulate units 
that were expressly exempted from regulation under the EPA regulations 
that Congress specifically incorporated by reference in the WIIN Act. 
According to this commenter, in 2015 EPA interpreted its RCRA Subtitle 
D statutory authority to regulate, as ``CCR units,'' only existing and 
new CCR landfills, existing and new CCR surface impoundments, and 
inactive CCR surface impoundments at active facilities, and Congress 
did not in 2016 grant the Agency any authority to regulate anything 
else. The commenter further claimed that EPA has acknowledged that the 
definition of a ``CCR unit'' does not include the areas of land that 
EPA proposed to regulate as CCRMU. Finally, the commenter objected that 
the proposal would regulate activities or sites that ``have 
historically been regulated under state programs, per EPA approved 
State Solid Waste Management Plans, and have closed or continued to 
operate in accordance with the State's program and plan.''
    EPA disagrees that the regulation of CCRMU under this final rule is 
fairly characterized as an ``unprecedented'' expansion of authority 
under RCRA Subtitle D or otherwise presents a major question under West 
Virginia v. EPA, 142 S. Ct. at 2609. The commenters have 
mischaracterized EPA's proposal, which largely just removes regulatory 
exemptions adopted in 2015, and requires the owners and operators of 
solid waste disposal units to clean up the contamination from their 
disposal of solid waste (CCR). These are the same requirements that 
apply to the currently regulated CCR landfills and CCR impoundments--
most of which are located at the same sites as the CCRMU regulated 
under this final rule--and that Congress incorporated into RCRA in the 
2016 WIIN Act. See, e.g., See, 42 U.S.C. 6945(d)(3), (6), (7). EPA has 
imposed these types of requirements on these kinds of entities and 
activities since 1980. Characterizing this as novel or unprecedented 
fundamentally misstates both the nature of EPA's action and the 
authority Congress delegated to the Agency in RCRA sections 1008(a)(3), 
4004(a), and 4005(d).
(a) Types of Units and Activities Regulated
    As an initial matter, these commenters have mischaracterized EPA's 
statements about the extent of its authority under subtitle D. EPA 
never stated that its authority was limited to the particular CCR units 
regulated by the 2015 CCR Rule. The only citation the commenter 
provides to support its assertion is 80 FR 21303, which is simply a 
factual recitation of the CCR units covered by the 2015 CCR Rule. That 
section contains no statement about EPA's authority to regulate; nor 
does any other section of the 2015 CCR Rule preamble contain such a 
statement.
    Similarly, EPA never stated or in any way suggested in the May 2023 
proposed rule that the existing regulatory definition of a CCR unit--
and by implication, the statutory term in 4005(d)--does not include the 
``areas of land that EPA proposed to regulate as

[[Page 39046]]

CCRMUs.'' Based on the pages in the proposal that the commenter cites, 
it appears the commenter was confused by EPA's explanation that it was 
proposing to use two different terms to distinguish between: (1) the 
CCR units that would be subject to all of the requirements in part 257 
and (2) the CCR units that would subject to only a subset of the 
existing requirements. EPA proposed to use the terms CCR unit and 
CCRMU, respectively, to refer to these two categories of units. To 
effectuate this, EPA proposed to revise the existing definition of a 
CCR unit by adding a statement that CCR management units are not 
covered by the definition. If the commenter were correct that EPA did 
not consider CCRMU to be a type of CCR unit, EPA would not have needed 
to revise the definition.
    But to the larger point, the CCRMU regulated under this rule 
clearly fall within RCRA sections 1008(a)(3), 4004(a) and 4005(d). In 
essence, as the commenter recognizes, CCRMU are simply CCR landfills 
and CCR surface impoundments that were not regulated by the 2015 Rule: 
inactive CCR landfills, or CCR surface impoundments and landfills that 
were closed prior to the effective date of the 2015 rule.\136\ As EPA 
explained in the May 2023 proposal, the proposed definition of a CCRMU 
was based on the existing definitions of a CCR pile--which is currently 
included in the definition of a CCR landfill--and of a CCR surface 
impoundment, which both rely on the concept of ``accumulations of 
CCR.'' See, 40 CFR 257.53 and 88 FR 32018. And the record for this 
rulemaking documents that the CCRMU regulated under this final rule 
present risks at least as significant as the units regulated under the 
2015 rule. CCRMU thus clearly are CCR units under both the regulations 
and the statute. As the commenter itself notes, when the WIIN Act was 
passed in 2016, and Congress incorporated the term CCR unit into the 
statute, the 2015 CCR Rule defined (and still defines) a CCR unit as 
``any CCR landfill, CCR surface impoundment, or lateral expansion of a 
CCR unit, or a combination of more than one of these.'' 40 CFR 257.53 
(emphasis added).
---------------------------------------------------------------------------

    \136\ The proposal described an additional category: any solid 
waste management that involves the placement or receipt of CCR 
directly on the land; such activities fall within the existing 
definition of a CCR pile, which is in turn defined as a CCR 
landfill.
---------------------------------------------------------------------------

    The commenter relies heavily on the fact that CCRMU were exempt 
under the 2015 CCR Rule; but that is ultimately irrelevant. First, as 
noted above, CCRMU actually fall within the 2015 regulatory definition 
of a CCR unit. More to the point, Congress did not define the term 
``CCR unit,'' thereby leaving it to EPA develop a definition. Although 
the WIIN Act incorporates the 2015 regulations into the statute, 
Congress simultaneously made clear that EPA retains the authority to 
modify or expand those requirements as necessary to ensure that the 
standard in section 4004(a) will continue to be met. See, e.g., 42 
U.S.C. 6945(d)(1)(A)(i), (3), (6) (referencing ``or successor 
regulations promulgated pursuant to sections 6907(a)(3) and 6944(a) of 
this title''). The commenters never acknowledge these provisions or 
address their logical implications.
    Instead, the commenters focus on two aspects of the CCRMU 
definition to support their claims of an ``unprecedented expansion'': 
(1) the proposal to define a CCRMU as ``any non-containerized 
accumulation of CCR'' without limitation or threshold; and (2) the 
regulation of ``any area of land'' on which CCR ``is received, placed, 
or otherwise managed at any time.'' With the incorporation of the 
thresholds in Sec.  257.50(d) the first issue has been rendered moot. 
EPA has also deleted the phrase ``at any time'' from the CCRMU 
definition. EPA had originally included that phrase to clarify that it 
did not matter when the CCR was originally placed, received, or 
otherwise managed, provided the CCR remained at the site. EPA deleted 
the phrase from the final definition because, as the D.C. Circuit 
explained, this concept is fully communicated by the phrase ``is 
placed.''

    Importantly, while the ``is'' retains its active present tense, 
the ``disposal'' takes the form of a past participle (``disposed''). 
In this way, the disposal itself can exist (it ``is''), even if the 
act of disposal took place at some prior time . . . . Properly 
translated then, an open dump includes any facility (other than a 
sanitary landfill or hazardous waste disposal facility), where solid 
waste still ``is deposited,'' ``is dumped,'' ``is spilled,'' ``is 
leaked,'' or ``is placed,'' regardless of when it might have 
originally been dropped off. See 42 U.S.C. 6903(3), (14).

    901 F.3d at 440. The same logic applies to the phrases ``is 
received'' and ``is otherwise managed.'' Including the phrase ``at any 
time,'' is consequently at best redundant, and at worst confusing--as 
demonstrated by the above comments.
    In any event, these aspects of the CCRMU definition were either 
taken directly from or largely mirror existing regulatory or statutory 
definitions. The phrase ``any non-containerized accumulation of CCR'' 
appears verbatim in the existing ``CCR pile'' definition, which as EPA 
previously explained, essentially mirrors the existing definition of a 
``waste pile or pile'' from Sec.  257.2 (i.e., the regulation that 
applied to CCR facilities prior to 2015), as well as the definition in 
part 260 that has been in place since 1982. See 80 FR 21356. Compare, 
Sec. Sec.  257.2, 257.53, and 260.10. More to the point, regulating the 
placement of non-containerized \137\ CCR directly on any land is fully 
consistent with RCRA's definition of disposal, which is defined in part 
as the `` `placing of any solid waste or hazardous waste into or on any 
land or water so that such solid waste or hazardous waste or any 
constituent thereof may enter the environment or be emitted into the 
air or discharged into any waters, including ground waters.'' 42 U.S.C. 
6903(3) (emphasis added). Similarly, and as illustrated by the D.C. 
Circuit decision quoted above, the phrase ``is received, is placed, or 
is otherwise managed,'' flows from the statutory definition of an open 
dump, which RCRA defines as ``any facility or site where solid waste is 
disposed of . . . .'' 42 U.S.C. 6903(14) (emphasis added).
---------------------------------------------------------------------------

    \137\ The phrase ``non-containerized'' means that specific 
measures to control exposures to human health and the environment 
have not been adopted. See 80 FR 21356.
---------------------------------------------------------------------------

    EPA responds to comments about the ``any area of land'' portion of 
the CCRMU definition in relevant portions of the discussions below.
(b) Extent of Requirements
    The commenters complain that the proposal was ``virtually 
unbounded'' as it would require operating power generation facilities 
to identify every CCRMU within its boundaries, even if located under 
existing structures critical to a plant's energy production operations, 
and to ``close,'' and in many cases reclose, those CCRMUs under the CCR 
rule's closure provisions. While EPA disagrees with the commenters' 
characterization of the proposal, the final rule, in any event, is more 
limited than the proposal, and is not unbounded. Under the final rule a 
covered facility must still identify every CCRMU of one ton or more 
within its boundaries, but groundwater monitoring, corrective action, 
closure, and post-closure requirements apply only to CCRMU containing 
at least 1,000 tons of CCR. Regulation of CCRMU between one and 1,000 
tons is deferred to a subsequent permitting authority who will assess 
the risks posed by these smaller CCRMU, individually and/or in the 
aggregate, and determine which, if any, requirements are appropriate 
for the CCRMU. In addition, this final rule defers the requirement to 
demonstrate

[[Page 39047]]

compliance with Sec.  257.102 for CCRMU that closed prior to the 
effective date of this rule in accordance with alternative, 
substantially equivalent requirements. EPA is also deferring the 
requirement to initiate closure where the CCRMU is located beneath 
critical infrastructure, such as high power electric transmission 
towers, air pollution control or wastewater treatment systems, or an 
electrical substation until the infrastructure is no longer needed, a 
permit authority determines closure is necessary to ensure that there 
is no reasonable probability of adverse effects on human health or the 
environment, or the closure or decommissioning of the facility, 
whichever occurs first.
    The commenters also objected to the imposition of corrective action 
and closure obligations on disposal units that were closed in 
accordance with State law or on areas where the State considered the 
placement of CCR on the land to be beneficial use under State law. But 
the regulation under subtitle D of closed or inactive disposal units or 
of activities exempt under State law is neither novel nor 
unprecedented. Indeed, many CCR units currently regulated under the 
2015 CCR rule were inactive or exempt under State law. See, 80 FR 
21322-21323, 21456. And in this case EPA is only extending the part 257 
regulations to activities or placements of CCR that, as discussed 
above, are already defined as ``disposal'' under Federal law--and that 
the record demonstrates present risks exceeding the threshold for 
regulation in section 4004(a).
    Under section 4004(a), EPA is charged with issuing regulations to 
address all ``reasonable probabilities of adverse effects'' (i.e., all 
reasonably anticipated risks) to health and the environment from the 
disposal of solid waste.\138\ The statute is clear that this includes 
regulations to address the current risks from previous solid waste 
management activities (including disposal). EPA explained at length the 
basis for this conclusion as part of the Agency's rationale for 
regulating inactive impoundments. See, 80 FR 21344-21345. See also 
USWAG, et al. v. EPA 901 F.3d at 440. See also In re Consolidated 
Consol. Land Disposal Regulation Litig., 938 F.2d 1386, 1389 (D.C. Cir. 
1991) (EPA's reading of the term ``disposal'' in RCRA's Subtitle C, 42 
U.S.C. 6924, to include ``the continuing presence of waste'' was 
reasonable); USWAG, 901 F.3d at 453-54 (Henderson, J., concurring) 
(same). By the same logic, these provisions authorize EPA to regulate 
inactive landfills and closed disposal units that continue to pose 
risks to health or the environment, for example by requiring the owners 
and operators of such units to remediate any contamination from these 
units, or to take action to prevent such contamination.
---------------------------------------------------------------------------

    \138\ Although section 1008(a)(3) expands EPA's authority to 
address the risks from any of the listed activities, the CCRMU 
regulated under this final rule--consisting of CCR surface 
impoundments and landfills (including CCR piles) only involve 
disposal.
---------------------------------------------------------------------------

    The 2016 WIIN Act amendments reaffirmed EPA's authority over these 
activities. In section 4005(d), Congress relied on the 2015 
regulations, and expressly stated that the amendments were not intended 
to limit or restrict the authority already provided under sections 
1008(a)(3) and 4004(a). See, 42 U.S.C. 6945(d)(3), (6), (7). With these 
amendments, Congress also affirmed the Agency's authority to impose the 
kind of requirements established in part 257 (e.g., corrective action 
to remediate groundwater contamination and closure to prevent it). This 
rule simply extends many of those same requirements to additional areas 
at which disposal of CCR is occurring--often at the same sites covered 
by the original 2015 CCR Rule. Moreover, Congress made clear that EPA 
retains the authority to modify or expand the requirements in the 2015 
CCR rule as necessary to ensure that the standard in section 4004(a) 
will continue to be met. See, e.g., 42 U.S.C. 6945(d)(1)(A)(i), (3), 
(6) (referencing ``or successor regulations promulgated pursuant to 
sections 6907(a)(3) and 6944(a) of this title''). None of the 
commenters acknowledge these provisions or address their logical 
implications.
    Moreover, this rule requires CCR facilities to remediate only the 
contamination associated with the disposal of CCR on site of a facility 
with other currently regulated CCR disposal units. Although expanding 
the corrective action obligations to other areas of CCR disposal on 
site may seem similar to the facility wide corrective action 
obligations applicable under the hazardous waste program--in that a 
facility will be required to clean up all of the on-site contamination 
caused by its disposal of CCR--the two requirements are not 
commensurate. For example, in contrast to a clean up under 3004(u), 
this rule does not require a facility to clean up any Appendix IV 
constituent from any source on-site, such as a spilled commercial 
product, unconnected to the solid waste (CCR) in the disposal unit. 
Rather, this rule imposes the same unit specific obligations that CCR 
facilities have been required to comply with since 2015, that were 
clearly authorized under 4004(a) and that Congress effectively affirmed 
in 2016 with the WIIN Act.
(c) Relationship to State Law
    Finally, EPA disagrees that either the proposed or final rule 
expands ``EPA's role in the Subtitle D statutory regime'' or otherwise 
alters the Congressionally mandated relationship between EPA and the 
States.
    The fact that EPA regulation affects the status of activities or 
units that were previously regulated under State law is precisely what 
the statute authorizes. Even under the more limited authority conferred 
upon the Agency prior to WIIN Act, EPA's subtitle D criteria 
established minimum national standards with which facilities were 
required to comply, irrespective of State law. See 80 FR 21310-21311.
    Moreover, the commenter has misunderstood both the intent and 
effect of the WIIN Act. Under the legal framework in place when the 
2015 CCR rule was enacted,

    EPA's delegated RCRA Subtitle D authority entails the authority 
to promulgate guidelines and criteria, to be implemented by the 
States, to prohibit open dumping and to ensure that units are 
classified as sanitary landfills ``only if there is no reasonable 
probability of adverse effects on health or the environment from 
disposal of solid wastes at such facility

    See 80 FR 21310-21311. Congress deliberately expanded EPA's role 
under that framework in 2016 when it granted EPA the authority to 
enforce the Federal criteria, issue permits in nonparticipating States, 
and to establish the minimum national standards that are both 
applicable directly to facilities and used to evaluate State programs. 
The commenter's description of the section 4005(d)(6) definition of a 
``sanitary landfill'' is similarly misleading. Congress did not define 
a sanitary landfill as a CCR unit that complies with any State CCR 
permit, but a State permit issued in accordance with an EPA approved 
program. See 42 U.S.C. 6845(d)(6)(A)(i).
(d) Other Comments Concerning Authority To Regulate CCRMU
    Other commenters stated that the proposed CCRMU definition exceeds 
the Agency's authority under RCRA subtitle D because EPA has failed to 
demonstrate that any amount of CCR placed anywhere on the land at any 
time presents the level of risk necessary to warrant regulation under 
section 4004(a). These commenters contend that the proposed CCRMU 
definition unlawfully eliminates the concept of risk out of the 
statutory definition of disposal. These commenters further asserted 
that the authority to regulate

[[Page 39048]]

``solid waste management practices'' under section 1008(a)(3) similarly 
does not authorize the regulation of any amount of CCR placed anywhere 
on the land at any time. Finally, a commenter raised concern that the 
proposed definition would encompass CCR used as fill material pursuant 
to acts of Congress or validly issued Section 404 permits under the 
Clean Water Act, which commenter alleged falls outside the scope of 
RCRA.
    EPA disagrees that it lacks the authority for any of the provisions 
in this final rule. The record demonstrates that the CCRMU regulated 
under the final rule meet the standard for regulation under section 
4004(a). This rule is supported by two separate risk assessments; the 
final rule adheres closely to the results, and regulates only the units 
and activities that present risks that warrant regulation under 
sections 1008(a)(3) and 4004(a). Further, the results of EPA's risk 
assessments are consistent with the damage cases discussed in Unit 
III.C.1 of this preamble.
    As discussed at length in Unit III.A of this preamble, leakage from 
CCRMU can adversely impact groundwater quality and pose risk to future 
receptors in the range that EPA typically considers for regulation. 
Closed and inactive landfills and surface impoundments pose 
substantially the same levels of risk to offsite receptors as those 
estimated in 2014 for currently regulated units. This is particularly 
true if the unit has not been properly closed, e.g., lacks a final 
cover system.
    In response to comments received on the proposed rule raising 
concerns about the adequacy of EPA's basis for regulating smaller 
CCRMU, EPA modeled groundwater concentrations at the boundary of 
smaller CCRMU fills to understand the potential for exceedance of GWPS 
that would trigger corrective action. The results of that 2024 Risk 
Assessment confirm that smaller CCRMU fills can pose risk to onsite 
receptors and materially contribute to broader groundwater 
contamination across the facility. In addition, depending on the 
location of these fills, they can also pose risk to offsite receptors 
that exceed the levels at which EPA normally regulates. On the whole, 
this analysis identified the potential for both moderate and high-end 
groundwater concentrations of molybdenum (among other Appendix IV 
constituents) to exceed GWPS.
    EPA conducted further sensitivity analysis to better understand 
whether there is an amount below which there is no reasonable 
probability of adverse impacts to groundwater quality. EPA remodeled 
quantities of CCR between one ton and 78,000 tons to determine both the 
risks associated with the potential for groundwater contamination and 
radioactivity. EPA modeled only individual placements of CCR in these 
quantities rather than the aggregate risks from the placement of 
multiple small quantities of CCR co-located at the same site.
    This analysis found that exceedances of the GWPS by a factor of as 
much as 40 are still possible for placements below 1,000 tons of CCR. 
Thus, such placements can meaningfully contribute to groundwater 
contamination at these facilities, including, for example by adding two 
contaminant plumes already present on site from larger placements, or 
in the aggregate. Although further analysis of the results indicates 
that there will be a tonnage that does not present a reasonable 
probability of adverse effects to groundwater quality, EPA was unable 
to identify that amount based on the available information. EPA 
conducted no modeling below one ton; however all indications in the 
existing data are that groundwater concentrations from individual 
quantities below one ton are very unlikely to exceed GWPSs. In other 
words, although EPA's modeling indicates that some amount between one 
ton and 1,000 tons is likely below EPA's level of concern, EPA cannot 
determine what that precise amount would be. It was not possible to 
identify a limit much lower than 1,000 tons because too few model runs 
were conducted at smaller amounts to support extrapolation.
    To ensure that the final rule is consistent with the Agency's 
authority under RCRA section 4004(a), this final rule incorporates 
thresholds consistent with the results of its risk analyses. 
Accordingly, the final rule only requires CCRMU containing 1,000 tons 
or more of CCR to comply with the applicable requirements for CCRMU.
    However, EPA estimated the risks associated with a 1,000 ton CCRMU 
to be an HQ of 40, which exceeds the Agency's normal level of 
acceptable risk by a significant margin. In addition, EPA's risk 
assessment may underestimate the risks at some sites. EPA modeled the 
risks associated with individual CCRMU of varying sizes, rather than 
the aggregate risks associated with numerous smaller CCRMU across the 
facility. It is possible that even though smaller CCRMU may not 
individually give rise to levels of concern, the risks may be greater 
when all of the CCRMU are considered together. According to many of the 
commenters, it is common for multiple small CCRMU to be located at a 
single facility. And although EPA's modeling estimated radiation risks 
of concern at lower quantities, EPA's concerns were based on a future 
residential use of the property (e.g., after clean closure of the 
regulated units, but where smaller CCRMU remain on site). As several 
commenters noted, current exposures at existing facilities 
(occupational) are very different. To address these risks, as section 
4004(a) requires, the final rule does not exempt CCRMU containing 
between one and 1,000 tons of CCR, but defers the regulation of such 
units to a permitting authority who will assess the risks posed by 
these smaller CCRMU, individually and/or in the aggregate, and 
determine which, if any, requirements are appropriate for the CCRMU to 
ensure there will be no reasonable probability of adverse effects on 
health or the environment. In order to facilitate this, the final rule 
requires facilities to identify these smaller units as part of the FER, 
so that this information can be submitted as part of their permit 
application. The facility will also continue to monitor the regulated 
units and larger CCRMU at the site, consistent with the requirements in 
this rule and the existing regulations. To the extent that these 
smaller unmonitored CCRMU are leaching contaminants and contributing to 
groundwater plumes, that should become apparent as the facility 
continues to monitor and conduct any necessary corrective action at the 
currently monitored units.
    EPA has codified these provisions in the ``Scope'' section of the 
regulations, at Sec.  257.50(d). The provision reads as follows:

    (1) This subpart applies to CCR management units of 1,000 tons 
or greater, located at facilities with a regulated CCR unit or 
active facilities without a regulated CCR unit.
    (2) CCR management units greater than or equal to 1 ton and less 
than 1,000 tons, located at facilities with a regulated CCR unit or 
active facilities without a regulated CCR unit, are only subject to 
the requirements of the facility evaluation report in Sec.  257.75 
until a permitting authority determines that regulation of these 
units, either individually or in the aggregate, is warranted and 
determines the applicable requirements.

    Finally, the commenter is mistaken that CCR used as fill material 
pursuant to acts of Congress or validly issued CWA section 404 permits 
under the State falls outside the scope of RCRA. To support its 
allegation, the commenter references section 1006(a), claiming that 
this ``expressly carves out any activity covered by 33 U.S.C. 1251 et 
seq.'' But RCRA section 1006(a) does not bar EPA

[[Page 39049]]

from imposing requirements under one of the listed statutes and RCRA on 
the same units and waste streams, unless those requirements are 
inconsistent with a requirement in one of the statutes. 42 U.S.C. 
6906(a). This is clear from the second sentence, which provides that 
``such integration shall be effected only to the extent that it can be 
done in a manner consistent with the goals and policies expressed in 
this chapter and in the other acts referred to in this subsection,'' 
and thus expressly contemplates that there will be situations in which 
EPA regulates under both RCRA and one of the listed statutes. Id. See, 
Chemical Waste Management v. EPA, 976 F2d 2, 23, 25 (D.C. Cir. 1992).
    Numerous courts have upheld this interpretation. See, Ecological 
Rights Foundation v. Pacific Gas & Electric Co., 874 F.3d 1083, 1095 
(9th Cir., 2017) (``RCRA's anti-duplication provision does not bar 
RCRA's application unless that application contradicts a specific 
mandate imposed under the CWA (or another statute listed in RCRA 
section 1006(a))''); Goldfarb v. Mayor and City Council of Baltimore, 
791 F.3d 500 510 (4th Cir. 2015) (The CWA must require something 
fundamentally at odds with what RCRA would otherwise require to be 
``inconsistent'' under 1006(a)); Edison Electric Institute v. EPA, 996 
F.2d 326, 337 (D.C. Cir.1993) (rejecting ``generalized claim'' that EPA 
action was barred under section 1006(a) because it interfered with 
``the primary purpose'' of the Atomic Energy Act); U.S. v. E.I. du Pont 
de Nemours & Co., Inc., 341 F.Supp.2d 215, 236 (W.D. N.Y. 2004) 
(approving EPA action as ``not inconsistent'' under RCRA where CERCLA's 
heightened standard would not be met by release of hazardous 
substance). The commenter has identified no requirement in the Clean 
Water Act that is inconsistent with EPA's regulation of CCRMU.
    The same is true with respect to the commenter's contention 
regarding acts of Congress. Although the commenter refers to ``acts of 
Congress'' it cites only to 33 U.S.C. 59d. That provision of the Clean 
Water Act states only that a particular area is not a water of the 
United States, and authorizes the owner to place fill in the area.

The old channel of the River Raisin in Monroe County, Michigan, 
lying between the Monroe Harbor range front light and Raisin Point, 
its entrance into Lake Erie, is declared to be not a navigable 
stream of the United States within the meaning of the Constitution 
and the laws of the United States, and the consent of Congress is 
hereby given for the filling in of the old channel by the riparian 
owners on such channel.

Regulation of CCRMU neither contradicts a specific mandate nor is 
fundamentally at odds with this provision, which does not require the 
owner to place CCR in the old channel or grant the owner an exemption 
from any requirement other than section 404 of the Clean Water Act.
ii. Subcategorization Is Appropriate for CCRMU Because CCRMU Are 
Dissimilar
    Commenters stated that the proposal groups all pre-2015 CCR Rule 
disposal areas into one large category. According to the commenters, 
this approach treats many different scenarios as a worst-case by 
imposing burdensome requirements for all. Commenters provided examples 
of potential subcategories, including: past CCR disposal varies based 
on site location (close to a surface water body), geography (eastern vs 
western sites), hydrology (flow variability/distance to uppermost 
aquifer), regulatory status (State closed-units vs unaddressed CCR 
sites), and historical CCR disposal areas currently used to harvest CCR 
for beneficial use. By categorizing all these situations together, the 
commenters claimed that EPA ignores the risk profiles of these 
subcategories and forces actions not tailored to the issues at hand. 
Some of these commenters opposed including in the CCRMU definition 
former landfills, impoundments and other accumulations of CCR that been 
closed in accordance with existing Federal or State regulations and 
regulatory oversight that pose no risk to groundwater.
    As discussed in Unit III.A, the risk record does not support the 
distinctions the commenters make. This final rule already imposes only 
a subset of the regulations in part 257 on CCRMU, consisting primarily 
of groundwater monitoring and closure. Corrective action is required 
only if triggered by site-specific determinations particular to 
individual units. EPA disagrees that the commenters have shown that any 
further differentiation is warranted.
iii. Size Threshold for a CCRMU
    Many commenters stated that the proposed definition of CCRMU does 
not provide the regulated community with ``fair notice'' of what in 
fact is forbidden or required. Citing to FCC v. Fox Television 
Stations, Inc., 567 U.S. 239, 253 (2012), these commenters stated that 
due process requires that ``laws which regulate persons or entities 
must give fair notice of conduct that is forbidden or required.'' 
According to these commenters, the proposed CCRMU definition does not 
give fair notice of what is regulated because it is an overly broad 
definition that would apply to ``any non-containerized accumulation of 
CCR.'' Furthermore, commenters raised concern that EPA has not provided 
any clarity on how much non-containerized CCR is enough to trigger 
regulation, nor does the proposal provide any criteria for determining 
significance, but instead points to examples where it does not expect 
this to be the case, such as closed or inactive process water ponds, 
cooling water ponds, wastewater treatment ponds, and stormwater holding 
ponds or aeration ponds. These commenters also questioned the 
references to evaporation ponds or secondary or tertiary finishing 
ponds that have not been properly cleaned up as examples of potential 
CCRMU, because in the 2015 CCR Rule preamble, EPA had identified these 
as examples of impoundments that would not be considered CCR surface 
impoundments because they contained only de minimis concentrations of 
CCR. These commenters argued that the burden is on EPA to provide the 
regulated community with ascertainable certainty as to what the 
regulation requires, a mark for which they believe the proposed CCRMU 
definition falls short.
    Commenters also pointed out that the limitations of or exemptions 
from the definition were only discussed in the preamble to the proposed 
rule but were not reflected in the regulatory text itself. These 
commenters argued that the CCRMU definition must include various 
limitations and exceptions in the final rule, such as, specifying a de 
minimis or insignificant quantity threshold in the definition of a 
CCRMU. Commenters further stated that without such clarity, owners or 
operators would be required to consider all CCR placement as CCRMU.
    As discussed in the preceding section, EPA has revised the rule to 
be consistent with the results of the 2024 Risk Assessment, and the 
final rule defers the regulation of CCRMU containing between one and 
1,000 tons of CCR to a permitting authority. Only CCRMU containing 
1,000 tons or more of CCR will be subject to the applicable 
requirements for CCRMU after the effective date of this rule. Although 
EPA has codified the thresholds in Sec.  257.50(d) rather than the 
CCRMU definition, the effect is the same. In addition, as discussed in 
more detail in Unit III.C.2.a, EPA has revised the CCRMU definition in 
response to concerns raised by commenters that the definition was 
confusing and unclear. The combined effect of these revisions is more 
than sufficient to address the commenters' concerns about the clarity 
of the definition including claims that

[[Page 39050]]

the proposed regulations would not provide regulated entities fair 
notice of what the regulations require.
    Finally, EPA acknowledges that the reference in the proposal to 
evaporation ponds, or secondary or tertiary finishing ponds that have 
not been properly cleaned up as examples of potential CCRMU was a 
mistake. EPA agrees that these units would generally be expected to 
contain no more than a de minimis amount of CCR.
iv. Exemption for Beneficial Use of CCR
    Several commenters stated that the CCRMU definition is too broad 
and does not account for the beneficial use of CCR. According to these 
commenters, the proposal to regulate CCRMU effectively revoked or 
amended the current exemption for beneficial use in Sec.  257.50, and 
the broad CCRMU definition now requires previously approved beneficial 
uses to be reexamined for potential regulation. Several of these 
commenters criticized the agency for failing to address the issue in 
the proposal, and argued that the Agency lacked the authority to 
include such beneficial uses, either because neither RCRA section 
1008(a)(3) nor section 4004(a) authorize EPA to regulate use or because 
such regulation would be inconsistent with the 2015 Regulatory 
Determination. These commenters recommended that the CCRMU definition 
be revised to exclude any beneficial use of CCR as defined by Sec.  
257.53 or as previously approved by State agencies.
    By contrast, several commenters request EPA to prohibit the use of 
coal ash as fill unless full protective measures such as liners, 
monitoring, and caps are required everywhere it is placed. Commenters 
claimed that immediate attention to this recommendation will protect 
the health and environment of millions of U.S. residents by preventing 
the spread of toxic coal ash pollution.
    EPA disagrees that the proposal to regulate CCRMU effectively 
revoked or amended the current exemption for beneficial use in Sec.  
257.50. The proposal merely accurately reflects the existing 
regulations, which these commenters have misunderstood.
    Under the existing regulations, the direct placement of CCR on the 
land on site of a utility, with nothing to control releases is, by 
definition, a CCR pile and therefore not beneficial use. The examples 
of historical CCRMU discussed in the proposal, structural fill and CCR 
placed below currently regulated CCR units on-site of a utility also 
clearly fit that definition.
    These are the same provisions that have been in place since 2015. 
The existing definition of a CCR pile is

Any non-containerized accumulation of solid, non-flowing CCR that is 
placed on the land. CCR that is beneficially used off-site is not a 
CCR pile.

Sec.  257.53 (emphasis added). The second sentence expressly limits the 
beneficial use of CCR to ``off site,'' and thus any non-containerized 
CCR placed directly on the land on-site of a utility is not beneficial 
use.
    EPA previously explained this in its August 14, 2019, proposal 
``Hazardous and Solid Waste Management System: Disposal of Coal 
Combustion Residuals From Electric Utilities; Enhancing Public Access 
to Information; Reconsideration of Beneficial Use Criteria and Piles'' 
to revise the definition of a CCR pile with respect to temporary piles. 
84 FR 40353. Specifically, EPA proposed to establish a new set of 
requirements that would apply equally to temporary or ``storage piles'' 
located on-site and off-site of a utility. As part of the background to 
that proposal, EPA described the requirements under the existing 
regulation so that the public could fully understand what it was-and 
was not \139\--proposing to revise. The proposal reiterated the 
existing definition of a CCR pile in Sec.  257.53, and explained that 
this definition closely mirrors the RCRA definition of disposal, which 
is defined in part as the ``placing of any solid waste or hazardous 
waste into or on any land or water so that such solid waste or 
hazardous waste or any constituent thereof may enter the environment or 
be emitted into the air or discharged into any waters, including ground 
waters.'' See 42 U.S.C. 6903(3). EPA further explained:
---------------------------------------------------------------------------

    \139\ EPA expressly advised the public that it was ``not 
reconsidering, proposing to reopen, or otherwise soliciting comment 
on any other provisions of the final CCR rule beyond those 
specifically identified in this proposal.'' 84 FR 40355.

Under this regulation, CCR piles constitute disposal and are 
consequently subject to all regulatory criteria applicable to CCR 
landfills. In contrast, activities that meet the definition of a 
beneficial use are not considered disposal, even if they involve the 
direct placement on the land of ``non-containerized'' CCR. See 
Sec. Sec.  257.50(g) and 257.53 (definitions of CCR landfill and CCR 
pile); 80 FR 21327-30.
The current regulation distinguishes piles of CCR on-site (at an 
electric utility or independent power producer site) from temporary 
piles of CCR off-site (at a beneficial use site), based on whether 
CCR from the pile could fairly be considered to be in the process of 
being beneficially used. See Sec.  257.53 (definition of CCR pile); 
80 FR 21356 (April 17, 2015). While the CCR from the pile on-site 
may someday be beneficially used, it is not currently in the process 
of being beneficially used . . . If CCR is not containerized, the 
pile is a CCR pile and subject to the same requirements as a CCR 
landfill. See Id.
In contrast, the regulations treat CCR stored off-site at a 
beneficial use site in a temporary pile to be in the process of 
being beneficially used (even though a pile is not itself a 
beneficial use). If the CCR is temporarily placed at a beneficial 
use site and meets the regulatory definition of a beneficial use, 
the pile is not a CCR pile and is not subject to disposal 
requirements.

. . . .

In the current definition [of a CCR pile], EPA distinguishes between 
piles on-site (which were almost always regulated as landfills) and 
piles off-site, (which, if temporary, were generally considered to 
be beneficial use, subject only to the four criteria in the 
definition). The current regulation also distinguishes between on-
site piles that are not containerized and those that are 
containerized. See 80 FR 21356 (April 17, 2017); Sec.  257.53.

84 FR 40365.

    Thus, under the 2015 CCR Rule the activities covered under the 
definition of a CCRMU (i.e., permanent placement of CCR on the land, 
on-site of a utility, without controlling releases) were defined as 
disposal rather than beneficial use. In 2019, EPA did not propose to 
revise or reconsider that. Instead, EPA proposed to extend that 
existing requirement to permanent piles located off-site of a utility. 
EPA therefore declines to reconsider the issue here.
    In the May 2023 proposed rule EPA expressly stated that it did not 
intend to reopen or reconsider any issue other than those on which the 
agency expressly solicited comment.

In this proposal, EPA is not reconsidering, proposing to reopen, or 
otherwise soliciting comment on any other provisions of the existing 
CCR regulations beyond those specifically identified in this 
proposal. For the reader's convenience, EPA has provided a 
background description of existing requirements in several places 
throughout this preamble. In the absence of a specific request for 
comment and proposed change to the identified provisions, these 
descriptions do not reopen any of the described provisions.

88 FR 31984. EPA further advised the public that it would ``not respond 
to comments submitted on any issues other than those specifically 
identified in this proposal, and such comments will not be considered 
part of the rulemaking record.'' Id.

    Nowhere in the May 2023 proposed rule did EPA solicit comment on or 
suggest that it was in any way reconsidering the existing definition of

[[Page 39051]]

a CCR pile. The sole mention in the proposal is EPA's explanation that 
its proposed definition of a CCRMU was ``based on the current 
definitions of a CCR pile--which is currently regulated as a CCR 
landfill. . . .'' Id at 32018. Consistent with the interpretation that 
all CCR placed on the land on-site of a utility is currently regulated, 
EPA also characterized structural fill and CCR placed below currently 
regulated CCR units on-site of a utility as ``historical'' solid waste 
management. Id. While commenters mischaracterize such activities as 
beneficial use, EPA's characterization of this conduct as 
``historical'' shows that the Agency assumed that facilities were 
complying with the existing requirement and had not continued these 
practices on-site.
    Accordingly, EPA declines the commenters' request to reconsider the 
definition of a CCR pile. EPA also declines to prohibit the use of CCR 
structural fill as part of this rulemaking. That issue is related to 
the 2019 proposal \140\ to revise the fourth criterion in the 
definition of beneficial use, which remains pending.
---------------------------------------------------------------------------

    \140\ 84 FR 40353 (August 14, 2019).
---------------------------------------------------------------------------

v. Exemption for Roadbeds and Associated Embankments
    EPA proposed to exempt CCR used in roadbeds and associated 
embankments. EPA further proposed that if a facility subsequently 
determined that the CCR in onsite roadbed is contributing to 
contamination of the aquifer, the facility would be required to address 
the contamination as part of the ongoing remediation.
    No commenters opposed EPA's proposal, and several commenters 
supported it. However, commenters pointed out that EPA had neglected to 
include an exemption for roadbeds and associated embankments in the 
proposed regulatory text.
    EPA is finalizing the exemption for roadbeds as proposed, and has 
amended the definition of a CCRMU accordingly.
b. Revision to Definition of CCR Unit
    In order to distinguish between CCR units that would be subject to 
all of the requirements in part 257, and those that would be subject to 
only a subset, EPA proposed to rely on two terms: (1) CCR unit and (2) 
CCR management unit. Under the proposal the term, ``CCR units'' would 
refer to only the units subject to all of part 257, subpart D. As 
defined in the proposal, the term ``CCR management unit'' would refer 
to the units subject only to the subset of groundwater monitoring, 
corrective action, closure, and post-closure requirements. To 
effectuate this EPA proposed to modify the definition of CCR unit by 
stating that CCR management units are not covered by the definition of 
a CCR unit. Under the existing regulations, CCR units are defined as 
``CCR landfills and CCR surface impoundments, as well as any lateral 
expansion of a CCR landfill or CCR surface impoundment. In addition, 
the term CCR unit already covers inactive CCR surface impoundments at 
active facilities because these units are CCR surface impoundments.'' 
40 CFR 257.53
    Commenters raised concern about the ``circularity'' of these 
definitions. and requested clarification on what type of unit would be 
considered a CCR unit, CCRMU, CCR landfill, or CCR surface impoundment. 
Several commenters noted that

``[f]or instance, `CCR landfill,' `CCR management unit,' and `CCR 
unit' are defined by reference to each other. For example, a `CCR 
landfill is `not a surface impoundment'' and not a `CCRMU,' while a 
`CCRMU' is ``not a CCR unit'' but includes `inactive CCR landfills' 
and ``CCR units that closed prior to October 17, 2015.'' And 
similarly, a `CCR unit' is ``not a CCRMU,'' but includes CCR 
landfills and CCR surface impoundments. Similar circular references 
are contained in the definitions of `inactive CCR landfill,' 
`inactive facility,' and `legacy CCR surface impoundment.'

Commenters claimed that defining one term by exclusion of another and 
in turn defining the latter term by exclusion of the former provides no 
clarity on the boundary between the two. These commenters went on to 
state that ``in a context in which definitional clarity is essential 
for regulatory clarity--i.e., what's ``in'' and what's ``out''--such 
ambiguity is fatal, EPA must clarify these definitions to define these 
terms by their essential characteristics, not by circular references to 
each other.'' And as discussed in a previous section, some commenters 
were also confused by EPA's explanation in the proposal that, because 
it planned to use the term ``CCR unit'' to refer only to those CCR 
units that would be subject to all of the regulations in subpart D, 
CCRMU would not be included in this term.
    In light of these comments, EPA reevaluated the proposed 
definitions and agrees that revisions are necessary. As noted, the 
proposed terms were intended to categorize units according to the 
requirements that would eventually be applied to them. EPA hoped that 
as a consequence, few revisions to the regulations would be necessary, 
with the idea that this would be less confusing to regulated entities 
and the public. Unfortunately, that was not the case and as the 
commenters noted, the definitions were frequently circular. 
Consequently, the final rule relies on three definitions: CCR unit, 
Regulated CCR unit, and CCR management unit.
    EPA has largely reverted to the existing definition of a CCR unit. 
The definition, as it was promulgated in 2015, provides that

``CCR unit means any CCR landfill, CCR surface impoundment, or 
lateral expansion of a CCR unit, or a combination of more than one 
of these units, based on the context of the paragraph(s) in which it 
is used. This term includes both new and existing units, unless 
otherwise specified.

Section 257.53. To avoid any ambiguity, EPA has also added a sentence 
stating that ``This term includes both Regulated CCR units and CCR 
management units.'' This is now the broadest term under the regulations 
and encompasses all units subject to 40 CFR part 257, subpart D.

    This final rule now also includes the term Regulated CCR unit, 
which refers to the units regulated by the 2015 CCR rule, i.e., new CCR 
landfills and new CCR surface impoundments (which include all lateral 
expansions of CCR landfills and CCR surface impoundments), existing CCR 
landfills, existing CCR surface impoundments, and inactive surface 
impoundments at active facilities. It also includes legacy CCR surface 
impoundments. Because legacy CCR surface impoundments will be subject 
to the same requirements as other inactive CCR surface impoundments, 
using this term will allow the Agency to implement this with relatively 
few revisions to the regulatory text.
    Finally, the final rule largely reverts to the proposed definition 
of a CCR management unit. This final rule defines CCR management unit 
to mean any area of land on which any noncontainerized accumulation of 
CCR is received, is placed, or is otherwise managed, that is not a 
regulated CCR unit. This term includes inactive CCR landfills and CCR 
units that closed prior to October 19, 2015. EPA has also included a 
definition of the phrase, ``closed prior to October 19, 2015,'' which 
provides that the term means ``the CCR landfill or surface impoundment 
completed closure of the unit in accordance with state law prior to 
October 19, 2015.''
    EPA deleted the phrase ``at any time'' from the proposed 
definition. EPA had originally included that phrase to clarify that it 
did not matter when the CCR was placed, received, or otherwise managed, 
provided the CCR remained present at the site. EPA deleted the phrase 
from

[[Page 39052]]

the final definition because, as the D.C. Circuit has already 
explained, this concept is fully communicated by the phrase ``is 
placed,'' and the inclusion of the phrase ``at any time,'' is therefore 
redundant. In addition, several commenters were confused by the phrase, 
assuming it meant that if CCR had ever been placed on the land at any 
time, even if it is no longer present, the site would be considered a 
CCRMU.
    These definitions are all codified in the regulatory text at Sec.  
257.53. EPA also made conforming changes throughout 40 CFR part 257, 
subpart D to clarify which types of CCR units are subject to which 
requirements. As discussed elsewhere in this preamble, consistent with 
the proposal, EPA is extending only a subset of the existing 
requirements in part 257, subpart D to CCRMU, consisting of 
requirements for groundwater monitoring, corrective action, closure, 
post-closure care, and recordkeeping.
c. Revisions to Definitions of Owner and Operator
    EPA proposed revisions to the existing definitions of Owner and 
Operator. The existing definition of Owner is the ``person(s) who owns 
a CCR unit or part of a CCR unit.'' First, EPA proposed to revise the 
definition to incorporate the concept of CCRMU into the existing 
definition because CCRMU would otherwise be excluded from the 
definition of a CCR unit as discussed in the preceding Unit of the 
preamble. This would be accomplished by adding ``or CCR management 
unit'' to the existing definition. Second, the Agency proposed to 
revise the definition of Owner to include the owner(s) of the entire 
facility, which would be achieved by adding ``or a facility, whether in 
whole or in part'' to the definition. EPA did not propose to revise the 
definition of a ``facility,'' which under the existing regulations 
means ``all contiguous land, and structures, other appurtenances, and 
improvements on land, used for treating, storing, disposing, or 
otherwise conducting solid waste management of CCR. A facility may 
consist of several treatment, storage, or disposal operational units 
(e.g., one or more landfills, surface impoundments, or combinations of 
them).'' 40 CFR 257.53.
    Some commenters opposed changing the definition of Owner. One 
commenter said ``It may be the current owner is unaware he owns the 
newly regulated facility. The current operator may have none of those 
parties responsible conducting activities since the parties may have 
ceased to exist long ago. Or, if the current owner is unwilling to work 
with those who previously disposed of the ash (potentially 
beneficially) there are legal issues (including potential access and 
trespass rules) that will need to be resolved.''
    Commenters agreed that it would not be appropriate to include an 
innocent owner provision, specifically because of the difficulty in 
defining complex owner structures where direct accountability is 
difficult to define. One commenter ``does not fully agree with this 
``limited accountability'' and suggest accountability must also honor 
indemnity and the assignment of liability defined in a Purchase and 
Sale Agreement (PSA). Specifically, any entity should transition or 
maintain liability based on an established purchase and sale agreement, 
thus responsibility cannot be limited to only the current owner. In 
addition, it is reasonable to expect that for known active or inactive 
CCR Units at an active facility, the current owner should be 
responsible for required closure that satisfies the requirements of the 
2015 CCR Rule and for corrective action that does not exceed industry 
standard for remediation. However, it is unreasonable to expect only 
current owners to be accountable for all past practices and the 
responsibility for the unknown, specifically for areas that were 
undefined and unknown and most importantly unregulated at the time of a 
transaction from a previous owner, most often a regulated utility.''
    EPA proposed and is finalizing this revision in part to account for 
the more complicated ownership arrangements that exist at some 
utilities. EPA has found that there may be multiple owners at the same 
facility; for example, one entity may hold title to a single 
impoundment, while another entity may own the remaining disposal units 
at the site. Moreover, ownership can change over time, as individual 
units or portions of the facility are parceled off. This final rule 
also more accurately reflects the nature of the obligations EPA is 
establishing for CCRMU. For example, as discussed below, EPA is 
finalizing the regulations to require an investigation of the entire 
facility to identify CCRMU. At many sites, this would involve areas 
other than those encompassed by the definition of a CCR unit, extending 
to all areas where disposal or other solid waste management may be 
occurring. Moreover, relying exclusively on the ``owner'' of the CCRMU 
may be ambiguous in this context, as at some sites the owner may not 
yet be aware that a CCRMU is present (e.g., because it results from the 
historic placement or accumulation of CCR). EPA recognizes that this 
final rule will apply to currently regulated facilities and newly 
regulated facilities, but EPA does not expect that this revision will 
actually amend the entities that currently are liable. EPA expects that 
most (if not all) utilities currently operate as though the regulation 
already required the owner and operator of the facility to take 
actions; for example, under the existing regulations owners and 
operators are required to conduct corrective action even where the 
plume has migrated beyond the footprint of the regulated unit. In 
addition, EPA is extending the deadlines for the CCRMU requirements, 
which can accommodate any issues with access to the facility in order 
to conduct the applicable requirements.
    For similar reasons, EPA proposed to revise the definition of 
Operator to incorporate the concept of CCRMU into the existing 
definition by adding ``or CCR management unit'' to the existing 
definition. In addition, the Agency proposed revisions to account for 
the unique characteristics of a CCRMU. In cases where the CCRMU is 
closed (i.e., not receiving waste or otherwise in operation) or is a 
historic placement or accumulation of CCR, there may not be an entity 
that neatly fits the normal concept of an ``operator,'' because there 
may not be any current or ongoing oversight or activity with respect to 
the continued use of the unit. To avoid any ambiguity, EPA proposed to 
revise the definition of ``operator'' to clarify that the term Operator 
includes those person(s) or parties responsible for disposal or 
otherwise actively engaged in solid waste management of CCR. It also 
includes those responsible for directing or overseeing groundwater 
monitoring, closure, or post-closure activities at a CCR unit or CCRMU.
    Commenters said the revised definition of operator is ``too broad 
and may be interpreted to impose CCR Rule liability on individuals or 
contractors who are retained by owners or operators to `actively 
engage' in CCR waste management. This definition should be revised to 
reflect the standard principles for `operator' liability under 
environmental laws, which should not include employees, individuals, or 
contractors operating under the direction of a responsible owner or 
operator.'' Another commenter disagreed with the revised definition of 
Operator, ``which can imply the operator could have obligations under 
this rule. We disagree. While some owners and operators are one and the 
same many facilities are operated by third parties operators and in 
these cases, such operators should have no obligations under this 
proposed rule. We request EPA clarify that distinction

[[Page 39053]]

and clearly state that third party operators have no obligation.''
    Another commenter stated ``Companies actively engaged in the solid 
waste management of CCR'' would include the construction contractors 
responsible for installation of CCR units including excavation, lining, 
filling, regrading, covering, closure, and more. Companies 
``responsible for directing or overseeing groundwater monitoring, 
closure or post-closure activities'' would include well drillers, the 
professional engineers who certify the plans for CCR units, and again, 
construction contractors. Contractors will no longer be willing to 
`actively engage[ ] in the solid waste management of CCR' or `direct[ ] 
or oversee[ ] groundwater monitoring, closure or post-closure 
activities' if they will consequently become liable for compliance with 
the CCR rule. As a result, the `shortage of contractors' will continue 
and grow worse. EPA should revise the definition of `Operator' to 
clarify that contractors are not Operators.''
    The revision to the definition of Operator is not intended to 
include every person who is ``actively engaged in the solid waste 
management of CCR'' but would follow the standard ``operator'' 
liability under environmental regulations. Such liability would include 
the operator who oversees the facility to ensure compliance with the 
regulations.
    Because multiple entities may potentially be liable, (i.e., owners 
and operators) EPA is providing the following guidance. Consistent with 
EPA's typical practice, unless otherwise provided in the regulations, 
as long as one responsible entity (an owner or operator) has complied 
with the requirements, EPA will consider the obligation satisfied as to 
all potentially liable parties and will initially rely on owners and 
operators to determine among themselves how best to ensure compliance 
with the requirements. See, e.g., 45 FR 33295 (May 19, 1980). (``EPA 
has no intention to require both owner and operator to take all or even 
most compliance actions in tandem. EPA will regard compliance by either 
owner or operator with any given obligation under the permit as 
sufficient for both of them'').
    EPA is finalizing the revisions to Owner and Operator as proposed 
without revision. This is codified in the regulatory text at Sec.  
257.53.
d. Conforming Revisions to Other Existing Definitions
    EPA proposed revisions to eight definitions in Sec.  257.53 to 
refer to CCRMU. These definitions currently refer only to CCR units and 
EPA proposed to add the words ``or CCR management unit'' to the 
definitions to incorporate the concept of CCRMU into the existing 
definition. The eight definitions for which EPA proposed this revision 
are: Active life or in operation, Active portion, Closed, CCR landfill 
or landfill, Qualified person, Qualified professional engineer, State 
Director, and Waste boundary. EPA received comments only about 
clarifying the definition of ``closed,'' which is discussed in the 
Volume II Response to Comments document. EPA did not receive comments 
about the other seven definitions for which EPA proposed this revision. 
As described in Unit III.C.2.b of this preamble, EPA has revised the 
definition of ``CCR unit'' in response to comments, and as a 
consequence the definitions for Active life or in operation, Active 
portion, Closed, Qualified person, Qualified professional engineer, and 
Waste boundary no longer need to be amended. EPA is finalizing the 
proposed revisions to the definitions of CCR landfill and State 
Director. These are codified in the regulatory text at Sec.  257.53.
e. Scope of Regulated Facilities With CCRMU
    EPA proposed to require the owners or operators of both active 
facilities with one or more currently regulated CCR unit(s) and 
inactive facilities with a legacy CCR surface impoundment to comply 
with the CCRMU regulations. The term active facility or active electric 
utilities or independent power producers is defined in Sec.  257.53. 
Inactive facilities are discussed in Unit III.A.1.c of this preamble.
    Some commenters on the proposed rule opposed limiting the universe 
to active facilities and inactive facilities with at least one CCR 
unit. They argued that CCR in landfills, dewatered surface 
impoundments, and CCRMU at other, currently unregulated, active 
facilities pose the same risks to groundwater, surface water, and air 
as facilities with CCR units. These commenters said RCRA section 
4004(a) cannot be met if these leaking units are arbitrarily excluded 
from regulation. Other commenters said EPA does not have the authority 
to regulate CCRMU at all and should limit the scope of the final rule 
to units that pose risks.
    After reviewing the comments on the proposed rule, EPA reconsidered 
whether the regulated universe should be expanded to include other 
facilities currently generating power for the electrical grid that only 
have CCRMU on-site. These unregulated active facilities, or ``Other 
Active Facilities,'' are those that: (1) On or after October 19, 2015, 
were producing electricity for the grid; (2) Had ceased placement of 
CCR in their on-site CCR units before the effective date of the 2015 
CCR Rule (October 19, 2015); and (3) Had no inactive CCR surface 
impoundments. As such, CCRMU (e.g., inactive CCR landfills, closed CCR 
landfills, or closed CCR surface impoundments) are located at these 
facilities. Commenters on the proposed rule identified 13 units at six 
other active facilities, based on sourced data, and these units 
including inactive CCR landfills, closed CCR landfills, or closed CCR 
surface impoundments. Based on the most recent information, including 
from NODA comments, EPA believes there are nine units at five other 
active facilities.\141\
---------------------------------------------------------------------------

    \141\ This universe is included in ``Universe of CCR Management 
Units. April 2024.'' in the docket for this action.
---------------------------------------------------------------------------

    The addition of these units provides regulatory consistency; the 
CCRMU at these active facilities pose the same risks to human health 
and the environment whether or not they are co-located with a currently 
regulated CCR unit or a legacy CCR surface impoundment. And with the 
expansion of corrective action and closure obligations to CCRMU, these 
facilities are more similarly situated to the currently regulated 
active utilities and independent power producers than they are to the 
inactive facilities that remain exempt under this final rule (i.e., 
inactive facilities with only CCRMU). Moreover, in contrast to the 
exempt facilities, EPA was able to identify the affected facilities and 
evaluate the potential consequences of regulating them.
    EPA disagrees that it lacks the authority to regulate these CCRMU, 
for the same reasons discussed in Units II.C and III.C.2.a of this 
preamble.
    The Agency also considered whether to regulate all CCRMU at 
inactive power plants. But as EPA explained in Unit III.B.1.b.i.(b) of 
this preamble, the location and number of inactive facilities without a 
legacy CCR surface impoundment are unknown, as is the number and 
condition of the units at these facilities. Without being able to 
better understand the full extent of the sites and entities that could 
be affected, EPA is not prepared to expand the regulations to this 
extent at the current time. Even though CCRMU pose the same risk when 
located at active or inactive facilities, EPA considers that the higher 
priority is to ensure that active facilities address the full extent of 
the contamination that currently exists, and to prevent further 
contamination at

[[Page 39054]]

these sites--in other word to address rather ``those ills we have, than 
fly to others that we know not of.''
    Therefore, EPA is finalizing amendments to regulate CCRMU at all 
active electric utilities or independent power producers that generated 
power for the electrical grid on or after October 19, 2015, in addition 
to those facilities with legacy CCR surface impoundments. As noted, EPA 
refers to these facilities as ``covered facilities'' throughout this 
preamble. This is codified in the regulatory text at Sec.  257.50(d).
3. Facility Evaluation for Identifying CCR Management Units
    EPA proposed that owners or operators of active facilities with a 
currently regulated unit or inactive facilities with a legacy CCR 
surface impoundment would need to conduct facility evaluations. The 
purpose of the facility evaluation is to confirm whether any CCRMU 
exist on-site, and, if so, to delineate the lateral and vertical extent 
of the unit(s). In developing the proposal, EPA relied heavily on the 
RCRA subtitle C Facility Assessment process for identifying solid waste 
management units at a hazardous waste facility. In addition, EPA 
accounted for certain existing requirements in the CCR regulations; for 
example, under the 2015 CCR Rule, facilities were required to compile a 
history of construction for their existing impoundments. 40 CFR 
257.73(c)(1). Facilities were generally able to obtain all information 
specified in Sec.  257.73(c)(1)(i) through (ix), even for units 
constructed decades ago. EPA expected that facilities will similarly be 
able to obtain the information that EPA proposed would be required in 
the Facility Evaluation Report (FER).
    EPA proposed that facilities prepare one report, to be completed in 
two consecutive steps, with a single deadline. As proposed, the first 
step would consist of a thorough review of available records in 
combination with a physical facility inspection and any necessary field 
work, such as soil sampling, to fill any data gaps from the information 
obtained from the review of available records. The second step of the 
facility evaluation would be to generate a FER to document the findings 
of the facility evaluation. EPA proposed separate deadlines to complete 
the investigation and to compile the report: a deadline of no later 
than the effective date of this final rule to initiate the facility 
evaluation and a deadline of no later than three months after the 
effective date to complete the FER. Commenters suggested that EPA 
follow more closely the investigation processes developed under the 
current RCRA and CERCLA regulatory programs, that is, RCRA Facility 
Assessment Guidance, CERCLA all appropriate inquiry (Phase I and Phase 
II) process. Commenters suggested that separating the information 
collection requirements from the physical evaluation requirements will 
provide a more thorough evaluation of existing available information to 
better inform the physical evaluation to fill data gaps and properly 
identify CCRMU.
    EPA is finalizing the procedures for facility evaluation for 
identifying CCR management units with a few revisions from the 
proposal. Owners or operators of any covered facilities will need to 
conduct a facility evaluation. The purpose of the facility evaluation 
is to confirm whether any CCRMU containing one ton (or more) exist on-
site, and, if so, to delineate the lateral and vertical extent of the 
unit(s). In developing the final rule EPA relied heavily on the 
investigation processes EPA developed under the current RCRA and CERCLA 
regulatory programs, that is, the RCRA subtitle C Facility Assessment 
process for identifying solid waste management units at a hazardous 
waste facility, and the CERCLA all appropriate inquiry (Phase I and 
Phase II) process.
    There is a two-step process for a facility evaluation. The first 
step consists of a thorough review of available records. The second 
step of the facility evaluation is to conduct a physical facility 
inspection and any necessary field work, such as soil sampling, to fill 
any data gaps from the information obtained from the review of 
available records.
    In response to comments, EPA examined facility evaluation processes 
currently being implemented under RCRA and CERCLA and concurs that 
creating two separate reports--one for each step of the process--is 
consistent with these established approaches. EPA believes this two-
step approach to facility evaluation will reduce the need for rework 
and the overall burden for both facility owners or operators and 
contractors who may be hired to complete this work. Additionally, EPA 
concludes this approach increases transparency by allowing the public 
the opportunity to see the work plan developed by the owner or 
operator.
    Therefore, the final rule creates two parts to the facility 
evaluation--the Part 1 FER includes the results of the available 
information collection and evaluation. The Part 2 FER addresses data 
and information gaps through a physical evaluation of the facility. 
Together, the Part 1 and Part 2 reports will give a complete picture of 
the historic use, placement and the current status of CCR at each 
facility, ultimately identifying any CCRMU containing 1,000 tons or 
more that will be required to meet the regulatory requirements of this 
final rule. The FER must also identify those CCRMU containing between 
one and 1,000 tons, whose regulations is deferred until permitting. 
See, Unit III.C.2.a.iii of this preamble for further discussion.
a. Final Requirements for Facility Evaluation for CCR Management Units
    During the facility evaluation, the owner or operator of a covered 
facility will need to identify and delineate the extent, laterally and 
vertically, of any CCRMU containing one ton or more at the facility. To 
begin, the owner or operator reviews all existing records and documents 
reasonably and readily available to (including information that is 
readily and reasonably attainable by) the facility, that contain 
information regarding any past and present CCR management that resulted 
in the accumulation of CCR on the ground. Consistent with the 
definition of a CCRMU, in this context EPA considers the terms 
``placement'' and ``receipt'' to include situations in which spilled or 
released CCR has been left on the ground. During this first step, the 
facility is required to gather and review reasonably and readily 
available information to identify potential locations of CCR placement 
at, and to determine preliminary boundaries, lateral and vertical 
dimensions, and estimates of volume of any CCRMU. Then, at the second 
step, the facility evaluation requires physical inspection of the 
facility. Where necessary, the physical inspection must include field 
investigation activities, such as conducting exploratory soil borings, 
geophysical assessments, or any other similar physical investigation 
confirmation activities to establish the location and boundaries of 
identified CCRMU, and to affirmatively rule out other areas of 
potential CCR placement at the facility that were identified during the 
information review. The scope of the facility evaluation is the entire 
facility as the term is currently defined in 40 CFR 257.53.
    As noted, the facility evaluation begins with a review of all 
reasonably and readily available information regarding past and present 
placement of CCR at the facility. In this first stage, the facility 
must gather all reasonably and readily available existing information 
that may be useful to determine any locations at the facility where CCR 
may have been placed (including spilled) on the ground. EPA expects 
that in this

[[Page 39055]]

initial phase, the facility will cast a wide net, and collect all 
reasonably and readily available information that could potentially 
contain useful information to identify the potential locations of CCR 
placement at the facility. Finally, to complete the information review, 
the investigatory process must be documented, any data gaps identified, 
and plans for conducting a physical inspection of the site to verify 
locations, boundaries, and volumes of CCR placement at the facility 
formalized. This information is documented in the Part 1 FER. Then, at 
Part 2, the physical inspection must be documented. Each step of this 
process is described in greater detail below.
    All recorded observations and data gathered during the facility 
evaluation, including any conclusions regarding the status of each 
CCRMU containing one ton or more of CCR at the facility (e.g., 
delineation of the lateral and vertical extent of each CCRMU and an 
associated site map that identifies the location of the CCRMU 
(including GIS coordinates)), must be assembled and incorporated into 
the FER.
    If, after conducting a thorough document review and a visual 
inspection, the facility has found no evidence of any CCRMU containing 
one ton or greater, no further testing or sampling is required to 
conclude that no such CCRMU are present at the facility. Consistent 
with the proposal, the final rule does not require facilities to 
conduct widespread site sampling to prove that no such CCRMU exists on-
site.
    The FER must include a certification to be signed by a P.E. and the 
owner or operator or an authorized representative. Owners or operators 
of active or inactive facilities with one or more CCR unit(s) that do 
not contain any CCRMU would need to complete and place in the operating 
record a certified FER documenting the steps taken during the facility 
evaluation to determine the absence of any CCRMU. Both Part 1 and Part 
2 of the FER must be placed in the facility operating record (Sec.  
257.105(f)(25)), submitted to the appropriate regulating entity (Sec.  
257.106(f)(24)), and published on the facility's website (Sec.  
257.107(f)(24)). Further, the Agency is requiring that the FER include 
a certification to be signed by the owner or operator or an authorized 
representative similar to the certification that is required at Sec.  
257.102(e) and (f) for existing units undergoing closure.
i. Facility Evaluation Report Part 1--Information Collection, Data Gap 
Identification
    The first step in the facility evaluation process involves the 
collection of reasonably and readily available information that 
contains any detail or information on whether CCR was either routinely 
and systematically placed on land, or where facility activities 
otherwise resulted in measurable accumulations of CCR on land. The 
quality and reliability of the information review will depend greatly 
on the owner's and operator's ability to collect relevant information. 
Information reviews may provide misleading results when significant 
sources of information are not considered. The information that must be 
gathered during this step should include any documents that contain 
information relevant to past facility operations and waste disposal 
processes. By the conclusion of the facility evaluation, EPA expects 
that the facility would be able to identify the date, locations, 
durations, and volumes or estimated quantities of CCR placement.
    EPA expects that the amount of available written information and 
documentation that will be available for review during the document 
review phase may vary by facility. However, the following documents 
developed as part of complying with 40 CFR part 257, subpart D, which 
are reasonably and readily available to facilities, would normally 
contain information that can be useful in identifying CCRMU: inspection 
reports; history of construction reports; fugitive dust control plans; 
annual groundwater monitoring and corrective action reports; ASDs; ACM 
reports or other corrective action reports; and closure plans and 
reports. Further, there are other sources of reasonably and readily 
available data that frequently contain information relevant to past 
facility operations and waste disposal processes, such as facility 
compliance reports produced for non-CCR programs (e.g., Toxic 
Substances Control Act [TSCA]/Occupational Safety and Health 
Administration [OSHA]/National Pollutant Discharge Elimination System 
[NPDES]/Clean Air Act [CAA]/Clean Water Act [CWA]); permits and permit 
applications, including NPDES, solid waste, dam safety, and air 
permits; historical and contemporary monitoring and reporting data, and 
facility operating logs and maps; and site imagery including available 
historical aerial photographs, site photographs, topographic maps, and/
or engineering or construction drawings, including drawings for 
physical facility improvement projects, such as surface water control, 
water and power infrastructure and utilities, roads, berms, ponds and/
or other physical features at the facility. EPA expects that facilities 
will search all reasonably and readily available records to determine 
whether they contain information relevant to the potential existence 
and locations of CCRMU containing at leat one ton of CCR.
    EPA proposed that as part of this process, owners and operators 
must further gather information by conducting meetings with current 
facility personnel familiar with the facility to the extent that those 
persons are available and have knowledge about past and/or present 
facility operations. The goal of the meeting process was to help gather 
any information relevant to the facility operations and waste disposal 
processes.
    Commenters objected that conducting interviews of current or former 
facility personnel and any available State and local officials is 
burdensome and will place a significant strain, specifically, on State 
and local agencies. In addition, commenters stated that interviews with 
State personnel would put the State personnel in a difficult position 
to verify compliance on EPA's behalf without receiving State permit 
approval first.
    In this final rule, EPA is not requiring the owner or operator to 
conduct interviews of current or former facility personnel, nor any 
available State and local officials. The regulatory language of the 
final rule only requires documentation of any interviews that are 
conducted as part of the information collection process. Nevertheless, 
owner and operator interviews of current or former personnel could well 
assist in identification of data and information that will be helpful 
in identifying CCRMU, particularly at those facilities that have not 
been in operation recently. Consequently, EPA continues to recommend 
that facilities use good faith efforts to collect information through 
interviews where current or past personnel are willing to assist in the 
identification of information or data that will assist the 
identification of CCRMU.
    During this stage, EPA is requiring that a P.E. review the 
documents and information gathered during the information review 
process to draw conclusions regarding the existence of CCRMU at the 
facility. At the end of this stage, EPA expects the facility to 
identify: (1) Any areas where the facility can affirmatively conclude 
based on the reasonably and readily available information that one or 
more CCRMU

[[Page 39056]]

containing greater than one ton are present; and (2) Any areas where 
the reasonably and readily available information indicates that CCR may 
have been either routinely and systematically placed on the land, or 
where facility activities otherwise could have resulted in one ton of 
CCR on the land (i.e., areas where the available information indicates 
that one or more CCRMU may be present).
    Each of the information sources discussed above can provide 
valuable information that can be used to identify the existence and 
locations of CCRMU. In addition, some specific examples are provided 
below:
     Environmental reports for multimedia inspections contain 
useful information on site management practices, monitoring data, and 
unit conditions. These reports can also describe comprehensive 
monitoring evaluations at the site that can indicate where releases or 
areas of concern exist.
     Multimedia permit and permit applications contain large 
amounts of information on the facility design, waste management 
practices including how wastes were disposed of, and the physical 
characteristics of the surrounding area. These documents can contain 
old topographic maps, facility figures and drawings, wastestream flow 
diagrams, and unit and process descriptions.
     If a groundwater monitoring report for a CCR unit 
indicates that contaminant levels in groundwater monitoring wells are 
the result of CCRMU rather than the monitored CCR unit, this would need 
to be further investigated during the facility evaluation process to 
fully delineate the locations of areas where CCR was placed on the 
ground, including the size of the unit and other related unit details.
     Similarly, a review of aerial photographs can identify 
potential CCRMU at the facility at locations that have become overgrown 
or otherwise hidden over time. When used in conjunction with USGS 
topographic maps, owners or operators can look for evidence that may be 
indicative of placement of CCR on the ground. As an example, if aerial 
photographs and USGS topographic maps indicate the existence of a pond 
or dam system at the site, this may be enough to warrant further 
investigation of available documents and may require field 
investigation depending on the strength of information to determine if 
the changes were made to allow placement of CCR on the ground.
    One of the primary purposes of the information review is to provide 
an understanding of the CCR management activities at the facility, 
allowing for subsequent observations during the physical site 
inspection to be focused to the greatest extent practical. While 
information obtained during the review may be insufficient to support 
affirmative conclusions regarding the existence or non-existence of a 
CCRMU, based on the information available at most facilities, EPA 
expects that it will be possible to determine which areas at the 
facility would need to be inspected, and the type of data that would be 
needed to draw definitive conclusions. The Agency expects that the 
information gathered in the information review will be relevant to 
determining the areas to be inspected during the physical (visual) site 
inspection. Further, the information gathered during the information 
review would be used to support any necessary field activities.
    EPA notes that the amount of available written information and 
documentation that will be available for review during the document 
review phase will vary by facility. Commenters confirmed this 
expectation by noting that many of the facilities subject to this final 
rule may have ceased operations years, and sometimes decades, ago. They 
also stated that record retention and storage locations may be 
difficult to determine and require some effort to access for some 
facilities. Based on past experience, EPA continues to believe that 
sufficient information is reasonably and readily available to allow 
facilities to obtain the information required under the FER. For 
example, as discussed in the proposal, under the 2015 CCR Rule 
facilities were generally able to obtain all of the information needed 
to compile a history of construction for their existing impoundments, 
even for units constructed decades ago. See, 40 CFR 257.73(c)(1). 
Nevertheless, owners or operators are required to compile this 
information only to the extent it is reasonably and readily available. 
EPA acknowledges that there may be certain information or data that may 
be unknown or lost. EPA intends that facilities provide relevant 
information only if documentation exists or if it is obtained during 
the physical site inspection. EPA does not expect owners or operators 
to provide anecdotal or speculative information regarding the presence 
or absence of CCRMU. However, if data gaps exist, owners or operators 
subject to these provisions may need to collect additional field data 
to fill the gaps.
    The Part 1 FER must also include a narrative that documents the 
data reviewed as part of the facility evaluation process, and that 
lists all of the data and information reviewed that indicates the 
presence or absence of CCR management units at the facility. Finally, 
the FER must identify any data gaps, and provide a plan for remedying 
all identified data gaps through a physical examination of the 
facility, including any field or laboratory work needed to remedy data 
gaps identified in the narrative in the Part 1 FER record. The plan 
must include the major milestones needed to fill each identified data 
gaps (e.g., a physical examination of the facility, sampling of media, 
measurements of CCR concentrations or physical presence, delineation of 
CCRMU) and dates to complete the needed tasks.
    EPA is finalizing that Part 1 FER must contain the following: (1) 
The name and address of the person(s) owning and operating the 
facility; the unit name associated with any regulated CCR unit and 
CCRMU containing one ton or more of CCR at the facility; and the 
identification number of each CCR unit and CCRMU if any have been 
assigned by the State or by the owner; (2) The location of any CCRMU 
identified on the most recent U.S. Geological Survey (USGS) 7.5-minute 
or 15-minute topographic quadrangle map, or a topographic map of 
equivalent scale if a USGS map is not available, with the location of 
each regulated CCR unit at the facility identified. The location of 
each regulated CCR unit at the facility must also be identified in the 
same manner; (3) A statement of the purpose(s) for which each CCRMU at 
the facility is or was being used; (4) A description of the physical 
and engineering properties of the foundation and abutment materials on 
which each CCRMU is constructed; (5) A discussion of any known spills 
or releases of CCR, including any associated remediation activities, 
from each CCRMU and whether the spills or releases were reported to 
State or Federal agencies; (6) Any record or knowledge of structural 
instability of each CCRMU; (7) Any record or knowledge of groundwater 
contamination associated or potentially associated with each CCRMU; (8) 
The size of each CCRMU, including the general lateral and vertical 
dimensions and an estimate of the volume of waste contained within the 
unit; (9) Identification of all types of CCR in each CCRMU at the 
facility; (10) A narrative description of any closure activities that 
have occurred, including any applicable engineering drawings or 
reports; (11) A narrative that documents the data reviewed as part of 
the facility evaluation process, and that lists all data and 
information indication the

[[Page 39057]]

presences or absence of CCRMU at the facility; (12) Any supporting 
information used to identify and assess CCRMU at the facility, 
including but not limited to any construction diagrams, engineering 
drawings, permit documents, wastestream flow diagrams, aerial 
photographs, satellite images, historical facility maps, any field or 
analytical data, groundwater monitoring data or reports, inspection 
reports, documentation of interviews with current or former facility 
workers, and other documents or sources of information used to identify 
and assess CCRMU at the facility; (13) narrative description of any 
data gaps, for information in paragraphs (c)(i) through (xiii) of this 
section, not available in existing information collection records and a 
plan for remedying identified data gaps through a physical examination 
of the facility, including any field or laboratory work needed to 
remedy data gaps in the FER Part 1 record. The plan must include the 
major milestones needed to fill the identified data gaps (e.g., a 
physical examination of the facility, sampling of media, measurements 
of CCR concentrations in and around the unit or physical presence, 
delineation of CCR management unit(s)) and dates to complete such 
needed tasks. Also, as necessary and timely, any updates to data gap 
remedy plans must be added to the public record during the FER Part 1. 
In addition, the FER is required to include a certification from a P.E. 
stating that the FER meets the requirements at Sec.  257.75(c).
ii. Facility Evaluation Report Part 2--Physical Evaluation and Remedy 
of Data Gaps
    A facility must conduct a physical site inspection of the entire 
facility in all cases. The purpose of the physical site inspection is 
to visually inspect the entire facility for evidence of CCR placement 
on the land, ensure that all CCRMU containing one ton or more of CCR 
have been identified, and fill any data gaps identified during the 
initial information evaluation. To that end, EPA is finalizing without 
revision the requirement that the physical site inspection must consist 
of a visual inspection of the entire facility to look for evidence that 
CCR is currently being managed on the land. At a minimum, a facility is 
required to visually inspect the site to confirm the information 
obtained from the information review phase and to identify any 
anomalies that warrant further investigation, such as an unnatural 
topographic rise or depression or an area where unspecified liquid 
waste was applied over several years. In addition, the facility is 
required to conduct any field work, such as soil sampling, necessary to 
determine whether areas that had been identified as a potential CCRMU 
in fact contain at least one ton of CCR and to obtain the information 
required for the FER.
    The complexity of past and current facility operations, combined 
with the amount of data that was available for review during the 
information review phase would impact how extensive the facility 
inspection must be. For example, if facility records are sparse or 
contain data gaps, the Agency expects that the facility inspection 
would be more thorough than in situations where detailed records exist. 
However, even in situations where detailed facility records exist, the 
facility must still conduct a visual inspection to ensure that all 
CCRMU containing one ton or more of CCR have been identified, whether 
or not those areas were identified in the initial document review. In 
addition, EPA expects that in most cases, a facility will need to 
conduct some sampling or other fieldwork to obtain all the information 
required for the FER. For example, even if the facility had as-built 
engineering drawings for an old landfill, EPA expects that in some 
cases the facility may still need to conduct some sampling to establish 
the lateral and vertical dimensions of the CCRMU.
    A facility can use a variety of visual means to inspect the entire 
site (e.g., physically walking the site, using motorized vehicles to 
inspect the site, using drone video footage to inspect the site) to 
confirm the information obtained from the information review in Part 1 
and to identify any anomalies that warrant further investigation, such 
as an unnatural topographic rise or depression or an area where 
unspecified liquid waste was applied over several years. EPA recommends 
that any sampling be conducted using standard industry methods, 
including any relevant standards and methodologies established by State 
environmental agencies. The FER must also include a discussion of 
quality assurance procedures, sampling equipment handling, sample 
collection, analytical methods, and data reporting.
    If, after conducting a thorough document review and a visual 
inspection, the facility has found no evidence of any CCRMU, no further 
testing or sampling would be required to conclude that there is no 
CCRMU present at the facility. EPA is not requiring facilities to 
conduct widespread site sampling to prove that no CCRMU exists on-site. 
All recorded observations and data gathered during the facility 
evaluation, including any conclusions regarding the status of each 
CCRMU at the facility, must be assembled and incorporated into a FER, 
which is described in detail below.
    EPA is finalizing that Part 2 FER must contain the following: (1) 
The name and address of the person(s) owning and operating the 
facility; the unit name associated with any regulated CCR unit and 
CCRMU containing one ton or more of CCR at the facility; and the 
identification number of each CCR unit and CCRMU if any have been 
assigned by the State; (2) The location of any CCRMU containing one ton 
or greater identified on the most recent U.S. Geological Survey (USGS) 
7.5-minute or 15-minute topographic quadrangle map, or a topographic 
map of equivalent scale if a USGS map is not available. The location of 
each regulated CCR unit at the facility must also be identified in the 
same manner; (3) A statement of the purpose(s) for which each CCRMU at 
the facility is or was being used; (4) A description of the physical 
and engineering properties of the foundation and abutment materials on 
which each CCRMU was constructed; (5) Any further evidence of known 
spills or releases of CCR, including any associated remediation 
activities, of CCR from each CCRMU and whether the spills or releases 
were reported to State or Federal agencies; (6) Any further evidence of 
structural instability of each CCRMU; (7) Any further evidence of 
groundwater contamination associated or potentially associated with 
each CCRMU; (8) The size of each CCRMU, including the general lateral 
and vertical dimensions and an estimate of the volume of CCR contained 
within the unit; (9) Identification of the types of CCR in each CCRMU; 
(10) A narrative description of any closure activities that have 
occurred, including any applicable engineering drawings or reports; 
(11) A narrative that documents the nature and extent of field 
oversight activities and data reviewed as part of the facility 
evaluation process, and that lists all data and information that was 
reviewed indicating the presence or absence of CCRMU at the facility; 
and (12) Any additional supporting information used to identify and 
assess CCRMU at the facility, including but not limited to any 
construction diagrams, engineering drawings, permit documents, 
wastestream flow diagrams, aerial photographs, satellite images, 
historical facility maps, any field or analytical data, groundwater 
monitoring data or reports, inspection reports, documentation of 
interviews with

[[Page 39058]]

current or former facility workers, and other documents or sources of 
information used to identify and assess CCRMU at the facility. In 
addition, the FER is required to include a certification from a P.E. 
stating that the FER meets the requirements at Sec.  257.75(c).
    In addition to the information described in numbers (1)-(12) in the 
preceding paragraph, Part 2 of the FER must include a narrative that 
documents the nature and extent of field oversight activities and data 
reviewed as part of the facility evaluation process, and that lists all 
data and information reviewed that indicated the absence or presence of 
any CCRMU containing one ton or more of CCR at the facility. The 
narrative must also discuss how each data gap identified in Part 1 was 
addressed. As many commenters stated, the physical examination and any 
field work will require the hiring of specialized contractors. EPA 
understands this level of field and laboratory work will require a 
detailed work plan, and EPA expects the FER Part 1 data gap remedy plan 
to reflect this detail, including milestones and time frames for 
completion. EPA also anticipates that as field activities commence, 
plans to address data gaps may change and/or additional field work may 
be necessary based on ongoing discoveries. In these cases, the owner or 
operators will need to update the plans accordingly and update the 
publicly available information in the Part 1 or Part 2 FER, depending 
on the timing of the update.
b. Certification of Facility Evaluation Report--Part 1 and Part 2
    The Agency proposed to require that the FER include a certification 
from a P.E. stating that the FER meets the requirements at Sec.  
257.75(c). Further, the Agency proposed to require that the FER include 
a certification to be signed by the owner or operator or an authorized 
representative similar to the certification that is required at Sec.  
257.102(e) and Sec.  257.102(f) for existing units undergoing closure. 
Commenters raised concerns that the rules were not sufficiently 
objective or technically precise for a P.E. to be able to certify. One 
commenter raised that EPA has indicated that no facility has 
successfully implemented the 2015 CCR Rule's requirements to date, even 
though facilities have secured the certification of Qualified 
Professional Engineers as prescribed by the 2015 CCR Rule.
    These commenters have misunderstood the purpose and role of the 
P.E. in the FER reports. The P.E. does not make final determinations; 
the role of the P.E. is to act as an engineer in information 
collection, data gap identification, physical site inspection, and 
remedy of data gaps and certify accordingly. As stated in the preamble 
of the 2015 CCR Rule, EPA reasoned that the requirement for a P.E. 
maintains the most important components of any certification 
requirement: (1) That the engineer be qualified to perform the task 
based on training and experience; and (2) that she or he be a 
professional engineer licensed to practice engineering under the title 
Professional Engineer which requires following a code of ethics with 
the potential of losing his/her license for negligence. The final rule 
requirements are sufficient for an P.E. to implement the final rule and 
follow industry standards.
    Other commenters raised that the P.E. certification requirement is 
overly burdensome and will extend the timeframe to complete the 
facility evaluation. EPA has re-structured the process for the FER by 
extending the time frame and separated the FER into two parts with 
separate and adequate time frames to prepare the reports. When 
determining the new compliance deadlines, EPA considered the shortages 
and backlogs of qualified contractors as well as the increased strain 
on those contractors.
    Another commenter asked for EPA to modify or add language to 
acknowledge the good faith and due diligence efforts of a P.E., 
especially when considering the age and nature of the potential CCRMUs. 
EPA does not agree with this suggestion. As discussed above, EPA 
discussed in the preamble of the 2015 CCR Rule that the P.E. follows a 
code of ethics with the potential of losing their license for 
negligence. As stated in the 2015 CCR Rule preamble, the Agency 
maintains that an engineer is able to give fair and technical review 
because of the oversight programs established by the State licensing 
boards that will subject the professional engineer to penalties, 
including the loss of license and potential fines if certifications are 
provided when the facts do not warrant it.
    EPA does not agree with suggestions to modify the certification and 
therefore we are finalizing the certification language as proposed.
c. Facility Evaluation Reports Deadlines
    The majority of the comments related to the timing and due date of 
the FER report stated that EPA had not allowed sufficient time to 
gather the required information and conduct a physical inspection of 
the facility. Comments cited many concerns with the proposed time 
frame, i.e., the time frame was too short to complete all the tasks 
required, for the FER, e.g., the difficulty in collecting historic 
information/data that may or may not be accessible at the facility or 
place of off-site records retention, the possible extensive volume of 
information, reports and/or data that owner or operators would need to 
review, the possible iterative nature of field work and sampling, the 
impact of seasonal disruptions to field work, the lack of qualified 
field personnel and the timing to acquire their services through 
contracts. Commenters suggested allowing significantly more time to 
complete individual aspects of the FER requirements.
    EPA has reviewed the information provided by commenters citing the 
shortages and backlogs of qualified contractors, increased strain on 
those contractors related to the number of CCR units complying with the 
CCR rule simultaneously, difficulty accessing and reviewing historical 
documentation, potential seasonal disruptions, and time needed to 
perform quality control and quality assurance, and considers it to be 
persuasive. After considering these factors EPA has extended the time 
frame and separated the FER into two parts with separate and adequate 
time frames to prepare the reports.
    The FER Part 1 is required to be prepared and placed in the 
operating record and posted on the facility's website, pursuant to 
Sec.  257.105(f) no later than 15 months after the effective date of 
the final rule. This time frame was determined based on suggestions 
from commenters as to the time necessary to conduct a thorough review 
of historic records, and, if necessary, conduct interviews of those 
with facility and site knowledge, and by EPA further considering the 
time needed under RCRA Subtitle C and CERCLA to do similar reviews for 
historic sites.
    The FER Part 2 is required to be prepared and included in the 
public record no later than 27 months after the effective date of the 
final rule. EPA established this time frame by also considering 
suggestions from commenters, who gave examples of timelines to hire 
contractors and conduct site work, as well as EPA's own experience and 
timelines at RCRA Subtitle C and CERCLA sites for conducting facility 
investigations. EPA believes the provided limited additional time is 
adequate to perform all necessary tasks under the FER, Part 1 and Part 
2 respectively.
    After completing the information gathering part of the facility 
evaluation process, owners or operators of covered facilities must 
compile and place in the operating record information pertaining

[[Page 39059]]

to every CCRMU containing one ton or more of CCR located at the 
facility no later than the deadline identified below. Both Part 1 and 
Part 2 of the FER must be posted to the facility's CCR publicly 
accessible internet site within 30 days of that date. In developing the 
list of items to be included in the FER, the Agency examined certain 
requirements from existing regulations for History of Construction 
reports that must be generated for existing CCR surface impoundments at 
Sec.  257.73(c)(1) as well as other requirements necessary to provide 
basic information about each CCRMU containing one ton or more of CCR at 
the facility.
    After gathering the information required for the FER Part 1 (i.e., 
not including a physical evaluation of the facility), the owner or 
operator must prepare a Part 1 FER by placing the information required 
in the facility's operating record as required by Sec.  257.105(f)(25).
4. Applicable Existing CCR Requirements for CCR Management Units and 
Compliance Deadlines
    EPA proposed that in addition to the facility evaluation 
requirements discussed in Unit III.C.3 of this preamble, owners or 
operators of a CCR facility comply with the existing requirements in 
part 257 for fugitive dust, groundwater monitoring, corrective action, 
closure, post-closure care, recordkeeping, notification, and internet 
posting. As explained in the preamble of the proposed rule, these 
requirements are intended to address the risks posed by any existing 
releases of CCR or CCR constituents to the groundwater, regardless of 
when the CCR was placed in the units and prevent future releases. The 
other existing requirements in 40 CFR part 257, subpart D are not 
necessary for CCRMU. For example, (1) since CCRMU should not contain 
sufficient liquids to create a hydraulic head or to otherwise cause the 
conditions that might lead to a structural failure, the structural 
stability requirements are not appropriate; (2) similar to legacy CCR 
surface impoundments, since CCRMU are existing units and will be 
required to close, the location restriction and liner design 
requirements would not be appropriate. EPA proposed that the fugitive 
dust, groundwater monitoring, corrective action, closure, post-closure 
care, recordkeeping, notification, and internet posting requirements 
apply to all CCRMU at active facilities and at inactive facilities with 
one or more legacy CCR surface impoundment.
    Several commenters generally supported the regulatory approach, 
although a commenter suggested that CCRMU be subject to more existing 
CCR regulations, namely the location restrictions at Sec. Sec.  257.60 
through 257.64, the liner design criteria at Sec.  257.71, and the 
structural stability requirements at Sec.  257.73. This commenter 
stated that these requirements were necessary to protect human health 
and the environment from the risk of failure posed by poorly 
constructed and sited CCRMU and to provide information ``critical'' to 
developing unit closure plans and any necessary corrective action.
    EPA disagrees that generally applying location restrictions, the 
structural stability requirements, and the liner design criteria to 
CCRMU would be appropriate. First, as explained in the proposed rule, 
the structural stability criteria are more appropriate for operational 
units and those units that maintain a hydraulic head. Second, the 
consequence of failing to comply with the location restrictions and 
liner design criteria requirements is closure by a specific date. 40 
CFR 257.101(a) through (b)(1). Except for those situations described in 
Unit III.C.4.e (i.e., deferral for CCRMU beneath critical 
infrastructure and deferral for CCRMU closed under a regulatory 
authority), because CCRMU are not operational CCR units and will in any 
event be required to close, the consequence for failure to comply with 
location restrictions or the liner design criteria (i.e., ceased 
receipt of waste and closure) is moot. Additionally, the commenter 
failed to identify any information necessary for conducting corrective 
action pursuant to Sec. Sec.  257.96 through 257.98 or closure in 
accordance with Sec. Sec.  257.101 and 257.102 that would be gained by 
requiring CCRMU to comply with the location restrictions or liner 
design criteria that would not be gained by compliance with the 
facility evaluation and groundwater monitoring requirements.
    Other commenters opposed the regulation of CCRMU holistically, 
citing lack of authority or lack of demonstrated risk to human health 
or the environment from CCRMU. Other commenters opposed EPA's proposal 
to apply specific existing requirements to CCRMU (i.e., groundwater 
monitoring, corrective action, closure). Several of the commenters that 
opposed requiring CCRMU to comply with the existing regulations stated 
that applying a ``one-size-fits-all'' approach to CCRMU was not 
appropriate due to the variety of units that would be captured in the 
definition of CCMRU and suggested the EPA wait to regulate these units 
until site-specific requirements could be developed (i.e., permitting 
programs). Comments regarding lack of authority or lack of demonstrated 
risk from CCRMU are summarized and addressed in Units III.A and 
III.C.2.a.i of this preamble, respectively. Comments about the 
applicability of specific existing requirements are described and 
responded to in later portions of this unit (Unit III.C.4). Regarding 
comments about the existing regulations being what commenters 
characterized as a ``one-size-fits-all'' approach to the variety of CCR 
units captured under the definition of CCRMU, EPA disagrees that the 
existing regulations are not holistically appropriate to apply to CCRMU 
or to address the potential risk from these units. Furthermore, 
commenters did not provide suggestions on how to regulate these units 
under the existing regulatory framework (i.e., self-implementing rule) 
and EPA, as explained in Units III.A and III.C.1, finds the risks posed 
by these units to be not only credible but significant enough to 
warrant regulation at this time (i.e., under the self-implementing rule 
as opposed to waiting until the Federal permitting program is 
established).
    In response to comments and for the reasons laid out below, EPA is 
finalizing the requirements for CCRMU to comply with fugitive dust, 
groundwater monitoring, corrective action, closure, post-closure care, 
recordkeeping, notification, and internet posting requirements. These 
requirements apply to all CCRMU at active CCR facilities, at inactive 
facilities with one or more legacy CCR surface impoundments, and at 
active facilities that ceased placement of CCR in onsite CCR units 
before October 19, 2015, regardless of how or when the CCR was placed 
in the CCRMU. These issues are discussed in more detail in this Unit of 
the preamble.
a. Compliance Deadlines for CCR Management Units
    EPA proposed compliance deadlines for CCRMU that closely aligned to 
the proposed compliance deadlines for legacy CCR surface impoundments. 
The proposed rule explained that the 2015 CCR Rule compliance deadlines 
were based on the amount of time determined to be necessary to 
implement the requirements and the proposed compliance dates for legacy 
CCR surface impoundments, and CCRMU were determined using the same 
approach. The proposed rule further explained that some factors 
considered in determining the 2015 CCR Rule compliance deadlines were 
not relevant for CCRMU, such as the need to coordinate compliance 
deadlines with

[[Page 39060]]

the then recently promulgated ELG rule. In addition, EPA anticipated 
most owners or operators of CCRMU would already be familiar with the 
existing regulations, and therefore most of the proposed requirements 
for CCRMU. Consequently, EPA proposed generally expedited deadlines, as 
compared to the 2015 CCR Rule deadlines, based on the expected shortest 
average amount of time needed to complete the necessary activities to 
meet the requirements. In the proposed rule, EPA requested comment on 
the proposed compliance deadlines and the feasibility of meeting the 
proposed compliance time frames for CCRMU.
    EPA received numerous comments regarding the proposed compliance 
deadlines. Several commenters expressed support for the proposed 
compliance deadlines for CCRMU. Generally, these commenters stated that 
expedited compliance was appropriate due to significant risk posed by 
these units, the likelihood that these units are actively contaminating 
groundwater, and the urgent need for corrective action to address that 
contamination for the protection of human health and the environment. 
Some of these commenters echoed the proposed rule, stating that owners' 
or operators' familiarity with the existing requirements, along with 
the fact that these units are no longer in use and therefore would not 
need time to cease receipt of waste, further justified the expedited 
deadlines.
    Many other commenters stated the proposed compliance deadlines were 
infeasible and should, at a minimum, allow as much time for compliance 
as the 2015 CCR Rule deadlines, although several commenters expressed 
that even the 2015 CCR Rule deadlines were inadequate, and that the 
insufficient time frames were likely a factor in the gap between EPA's 
expectations and facilities' good faith efforts and utilization of best 
practices in developing groundwater monitoring networks, sampling and 
analysis plans, corrective action programs, and closure plans. 
Commenters pointed to several factors that they believed EPA did not 
fully incorporate into the proposed deadline calculations that make 
compliance with the proposed deadlines infeasible: EPA's grossly 
underestimated number of CCRMU; the large number of CCR units (i.e., 
existing CCR units, legacy CCR surface impoundments, CCRMU) competing 
for limited resources to meet overlapping compliance deadlines; the 
limited number of qualified contractors available to conduct necessary 
activities to reach the compliance deadlines; the nationwide labor 
shortage exacerbated by impacts from the COVID-19 pandemic; limited 
existing alternative disposal options; overlapping regulatory 
requirements (e.g., State drilling permits, timing restrictions related 
to protected habitats, State CCR permits, Consent Decrees/Orders); 
seasonality impacts in different regions across the nation; and 
accessibility and completeness, or lack thereof, of historical 
documentation and information. One commenter provided specific 
information regarding typical delays experienced during the 
implementation of the 2015 CCR Rule caused by third-party availability 
and backlogs: two to four weeks for contractor mobilization; two to six 
weeks for site clearing; two to three weeks for surveys; three to 12 
weeks for environmental drillers; and three to four weeks for 
laboratory analyses. These commenters also said EPA grossly 
underestimated the amount of time needed to hire a contractor, locate 
and review historical information, access historical or heavily 
vegetated portions of facilities, characterize and delineate a site, 
comply with the groundwater monitoring requirements, and conduct 
quality control or quality assurance on data and reports. Several of 
these commenters expressed the belief that the proposed deadlines would 
result in unintentional non-compliance despite facilities' best efforts 
to comply due to the constraints listed above. Finally, a few 
commenters suggested EPA create alternative deadlines or mechanisms for 
extensions based on site-specific characteristics.
    In response to comments, EPA reevaluated the compliance deadlines 
for CCRMU. EPA reconsidered the impact of the following on the amount 
of time facilities needed to complete the activities involved in 
meeting the requirements: the potential size of the CCRMU universe; 
accessibility and abundance, or lack thereof, of historical 
documentation; seasonality; clearing restrictions and required local 
and State approvals to clear vegetation or drill wells; need to 
coordinate with local or State regulatory authorities; existing 
disposal options; impact of the national labor shortage and contractor 
and laboratory backlogs; and the strain on limited resources from 
overlapping compliance deadlines for legacy CCR surface impoundments, 
existing units (i.e., groundwater monitoring, closure, and post-closure 
care), and CCRMU. Overall, EPA found the information provided regarding 
the infeasibility of the proposed deadlines convincing. Specifically, 
EPA acknowledges the potential for an underestimation of the CCRMU 
universe given the number of comments received regarding non-
containerized CCR historically being spread across facilities. 
Additionally, EPA agrees that the shortage of qualified contractors and 
laboratory resources has persisted, if not increased, since the 2015 
CCR Rule and that the increasing demand on these finite resources from 
new and existing CCR units, legacy CCR surface impoundments, and CCRMU 
complying with overlapping requirement deadlines will likely result in 
additional delays. EPA acknowledges that the proposed deadlines did not 
adequately account for those nationwide impacts of seasonality and 
extreme weather events; necessary coordination with outside parties 
(e.g., State agencies, local governments); locating disposal capacity 
for those units closing by removal; the need to comply with overlapping 
regulatory requirements, such as State drilling permits or timing 
restrictions related to protected habitats; or necessary quality 
assurance and quality control in calculating the proposed deadlines. 
Furthermore, as detailed in Unit III.C.3.c, EPA recognizes that the 
proposed CCRMU deadlines did not provide sufficient time for the 
completion of the FER which serves as the prerequisite requirement for 
all other CCRMU requirements. Additionally, the concurrent deadlines 
for legacy CCR surface impoundments and CCRMU did not allow for 
inactive facilities to first determine if there is a legacy CCR surface 
impoundments onsite before complying with the CCRMU regulations. 
Therefore, as detailed in Units III.C.3 and III.C.4.c through e, EPA 
extended the deadlines for CCRMU to provide: (1) At least as much time 
facilities had to come into compliance with the 2015 CCR Rule, (2) 
Sufficient time for owners or operators to complete a robust FER, and 
(3) Additional time such that the deadlines for legacy CCR surface 
impoundment do not coincide with the CCRMU deadlines, with the 
exception of the requirement to establish a CCR website and the 
completion of the history of construction (for legacy CCR surface 
impoundments) and the FER Part 1 (for CCRMU) which can be conducted 
concurrently. These extended deadlines for CCRMU will mitigate factors 
mentioned by commenters that convinced EPA the proposed deadlines would 
be infeasible for CCRMU. Overall, most of the comments EPA received 
supported deadlines that allowed at least as much time as EPA 
originally provided in the 2015 CCR Rule.

[[Page 39061]]

    Note that all deadlines herein are framed by reference to the 
effective date of the rule; the final rule will be effective six months 
after publication of the final rule. Accordingly, facilities will have 
an additional six months beyond the deadlines to come into compliance. 
The Agency has included a document in the docket for this rule that 
summarizes the finalized compliance deadlines.\142\
---------------------------------------------------------------------------

    \142\ A document ``Final Rule Compliance Deadlines for CCR 
Management Units. April 2024.'' is available in the docket for this 
action.

                                 Table 2--Final Compliance Time Frames for CCRMU
----------------------------------------------------------------------------------------------------------------
                                            Description of       Deadline (months after
      40 CFR Part 257, Subpart D          requirement to be      effective date of the             Date
             requirement                      completed               final rule)
----------------------------------------------------------------------------------------------------------------
Internet Posting (Sec.   257.107)....  Establish CCR website..  15.....................  Monday, February 9,
                                                                                          2026.
Facility Evaluation Report (Sec.       Complete the Facility    15.....................  Monday, February 9,
 257.75).                               Evaluation Report Part                            2026.
                                        1.
Facility Evaluation Report (Sec.       Complete the Facility    27.....................  Monday, February, 8,
 257.75).                               Evaluation Report Part                            2027.
                                        2.
GWMCA (Sec.   257.91)................  Install the groundwater  42.....................  Monday, May 8, 2028.
                                        monitoring system.
GWMCA (Sec.   257.93)................  Develop the groundwater  42.....................  Monday, May 8, 2028.
                                        sampling and analysis
                                        program.
GWMCA (Sec.  Sec.   257.90-257.95)...  Initiate the detection   42.....................  Monday, May 8, 2028.
                                        monitoring and
                                        assessment monitoring.
                                        Begin evaluating the
                                        groundwater monitoring
                                        data for SSIs over
                                        background levels and
                                        SSLs over GWPS.
GWMCA (Sec.   257.90(e)).............  Complete the initial     January 31, 2029.......  January 31, 2029.
                                        annual GWMCA report.
Closure (Sec.   257.102).............  Prepare written closure  48.....................  Wednesday, November 8,
                                        plan.                                             2028.
Post-Closure Care (Sec.   257.104)...  Prepare written post-    48.....................  Wednesday, November 8,
                                        closure care plan.                                2028.
Closure and Post-Closure Care (Sec.    Initiate closure.......  54.....................  Tuesday, May 8, 2029.
 257.101).
----------------------------------------------------------------------------------------------------------------

b. Fugitive Dust Requirements for CCR Management Units
    The air criteria in the existing regulations address the pollution 
caused by windblown dust by requiring the owners or operators of CCR 
units to minimize CCR from becoming airborne at the facility. 40 CFR 
257.80. These requirements apply to the entire facility, which means 
that the owner or operator is required to minimize CCR fugitive dust 
originating not only from the CCR unit, but also from roads and other 
CCR management and material handling activities at the facility. 
Consequently, under the proposal, CCRMU would already be covered by the 
fugitive dust requirements in Sec.  257.80 because CCRMU are located at 
facilities with a CCR unit. EPA therefore only proposed to make those 
changes to the fugitive dust requirements in Sec.  257.80 that are 
necessary to make clear that these requirements also apply to CCRMU. 
Specifically, EPA proposed to amend the regulations to add ``CCRMU'' to 
the list of units subject to the requirements under Sec.  257.80 and 
associated provisions under Sec. Sec.  257.105 through 257.107. 
Additionally, EPA solicited comments on amending Sec.  257.80(b)(6) to 
include a deadline for facilities to amend the fugitive dust control 
plan no later than 30 days following a triggering event, such as the 
closure of a CCRMU or change in facility or CCR unit operations.
    No commenters raised concern about requiring CCRMU to comply with 
the existing requirements in Sec.  257.80. EPA is therefore finalizing 
this provision without revision.
    One commenter supported creating a deadline for the amendment of 
the fugitive dust plan no later than 30 days following a triggering 
event. This commenter went on to suggest that EPA further revise Sec.  
257.80 to require owners or operators to notify potentially impacted 
populations including residents living within three miles of the plant, 
populations potentially impacted by transportation of CCR, and 
residents living near disposal areas where CCR will be off-loaded and 
disposed and to require air monitoring at excavation sites and plant 
boundaries. The commenter was not clear on the circumstances in which 
owners or operators would notify potentially impacted population or 
what these populations would be notified of and did not provide a 
factual basis to support the need for air monitoring at regulated CCR 
units. Therefore, EPA is therefore only finalizing an amendment to 
Sec.  257.80(b)(6) to require owners or operators to amend the fugitive 
dust plan no later than 30 days following a triggering event, such as 
the closure of a CCR unit or change in facility or CCR unit operations.
c. Groundwater Monitoring and Corrective Action Requirements for CCR 
Management Units
    EPA proposed to require CCRMU to comply with the existing 
groundwater monitoring and corrective action criteria in 40 CFR 257.90 
through 257.98, with one revision, to require sampling and analysis of 
constituents listed in Appendix IV at the same time as those listed in 
Appendix III. As explained in the proposed rule at 88 FR 32003, 
Sec. Sec.  257.90 through 257.95 require owners or operators of a CCR 
unit to install a system of monitoring wells, specify procedures for 
sampling these wells, and set forth methods for analyzing the 
groundwater data collected to detect hazardous constituents (e.g., 
toxic metals) and other monitoring parameters (e.g., pH, total 
dissolved solids) released from the units. If the groundwater 
monitoring required in Sec.  257.95, demonstrates an exceedance of the 
groundwater protection standards for constituents identified in 
Appendix IV of part 257, corrective action is required as laid out in 
Sec. Sec.  257.96 through 257.98. These requirements apply until 
closure in accordance with Sec.  257.102(c) is

[[Page 39062]]

complete or the post-closure care period of the CCRMU ends.
    Several commenters expressed support for requiring CCRMU to comply 
with these groundwater monitoring and corrective action requirements, 
stating CCRMU can and have caused groundwater contamination. Some 
commenters suggested additional requirements be added to those in 
Sec. Sec.  257.90 through 257.98, including a mandate to test 
groundwater quality outside the boundary of the facility and make those 
results public, a deadline for the completion of the selection of 
remedy required by Sec.  257.97, and a prohibition against using 
intrawell groundwater data comparisons at CCRMU. However, other 
commenters stated that applying the existing groundwater monitoring and 
corrective action requirements to CCRMU is not appropriate and 
suggested that instead EPA incorporate flexibility into the CCRMU 
regulations by providing for alternative groundwater monitoring 
standards and site-specific risk-based corrective action into the CCR 
regulations. These commenters suggested groundwater monitoring 
standards that allow owners or operators to complete evaluations to 
determine if Appendix IV constituents are above the GWPS instead of 
conducting monitoring, allowing a site-wide groundwater network, and 
exempting units from groundwater monitoring when owners or operators 
are able to demonstrate through site-specific risk assessments there is 
no probable risk to groundwater. These commenters said these 
alternative approaches are necessary to address the overburdensome 
nature of compliance with groundwater monitoring and corrective action 
when a unit has already completed closure under a State authority and 
when units are completing groundwater monitoring under a State or other 
Federal program. Some of these commenters stated that EPA does not have 
the record to demonstrate potential risk from these units to justify 
requiring groundwater monitoring and corrective action as laid out in 
the existing regulations, especially for units that have already 
completed closure under a State authority. Other commenters said that 
flexibility is needed due to the diversity of CCR units captured in the 
definition of CCRMU, age of some of the units, and overlapping State 
requirements.
    EPA further proposed two deadlines for the groundwater monitoring 
requirements, as opposed to the single deadline in the 2015 CCR Rule. 
EPA received numerous comments on EPA's proposal to split the single 
deadline for groundwater monitoring requirements contained within the 
2015 CCR Rule (24 months from the effective date of the final 2015 
rule) into two separate deadlines (six months from the effective date 
of the final rule for the installation of the groundwater monitoring 
network and development of the groundwater sampling and analysis plan 
and 24 months from the effective date of the final rule for the 
initiation of the combined detection and assessment monitoring). A few 
commenters expressed support of the two separate deadlines for 
groundwater monitoring requirements, stating it increased 
accountability and ensured owners or operators were not unnecessarily 
delaying the installation of the groundwater monitoring system. 
However, overall, commenters stated that the groundwater monitoring 
requirements should have a single deadline as the separate deadlines 
made compliance with the rule infeasible. Several commenters said the 
proposed split deadlines eliminated the flexibility necessary for 
compliance that was contained within the 2015 CCR Rule's single 
deadline. Those commenters went on to say the single deadline allowed 
facilities to accommodate for delays associated with factors outside 
their control, such as third-party availability, weather, and required 
permits or approvals, by making schedule adjustments necessary to 
achieve compliance (e.g., expedite the development of the sampling plan 
in the case of delays with the well installation). Other commenters 
said the proposed two deadlines were unnecessarily prescriptive. One 
commenter pointed out that the proposed rule contained no deliverables 
to verify compliance for the installation of wells or the development 
of the sampling and analysis plan.
    As explained in the proposed rule, the existing groundwater 
monitoring and corrective action requirements are essentially the same 
requirements that have been applied to both hazardous waste and 
municipal solid waste disposal units for decades, and with the one 
exception discussed below, there is nothing about CCRMU that makes them 
distinct enough to warrant separate groundwater monitoring requirements 
from other CCR units. No commenter provided any factual basis for 
treating CCRMU differently than all of the other units that currently 
comply with the same groundwater monitoring and corrective action 
requirements. Specifically, for commenters who requested alternative 
groundwater monitoring requirements to allow site-wide or property-
boundary groundwater monitoring due to the potential presence of CCRMU 
across the facility, the commenters failed to explain how the 
provisions at Sec.  257.91(d), which allow for multiunit groundwater 
monitoring systems fail to address their concern.
    Regarding the request for alternative groundwater monitoring 
criteria to mitigate the inappropriateness of requiring compliance with 
the CCR groundwater monitoring and corrective action requirements when 
the CCRMU has already completed closure under a State authority or when 
the CCRMU is already subject to another State or Federal groundwater 
monitoring program, the commenters did not provide any factual or 
specific information to support the conclusions that groundwater 
monitoring and corrective action is not appropriate for all CCRMU that 
have completed closure under a State authority or that utilizing or 
augmenting an existing groundwater monitoring network that may have 
been required as part of the State closure or other groundwater 
monitoring program would be infeasible or inappropriate. Furthermore, 
as explained in Unit III.C.4.e, EPA received comments regarding State 
closures during which no groundwater monitoring was required, thereby 
highlighting the need for groundwater monitoring and corrective action, 
if necessary, even in situations in which closure has been completed 
under a State authority.
    For those commenters requesting that EPA adopt ``risk-based 
groundwater monitoring and corrective action'' into the requirements, 
EPA notes that the commenters have provided no further explanation of 
what requirements in the existing regulations they wanted EPA to 
revise, what the revisions should accomplish, or any factual basis for 
why they are necessary or appropriate. As a general matter EPA 
considers that the corrective action regulations in Sec. Sec.  257.95 
through 257.98 do currently require facilities to tailor remedies to 
address the risks to human health and the environment, based on the 
conditions at the site. It is unclear what more the commenters are 
seeking. Accordingly, EPA is finalizing the proposal that CCRMU comply 
with the existing groundwater monitoring and corrective action 
requirements with one modification, combined detection and assessment 
monitoring.
    However, EPA agrees that having a single deadline for groundwater 
monitoring requirements as opposed to two deadlines allows flexibility 
to complete tasks, such as installing groundwater wells and collecting

[[Page 39063]]

independent samples, that is necessary for compliance with a nationwide 
rule. The activities involved in achieving compliance with the 
groundwater monitoring requirements (i.e., drilling wells, collecting 
samples, receiving lab results) are more susceptible to factors outside 
a facility's control, such as extreme weather events, shortages of 
qualified contractors, and permitting or approval delays, and 
therefore, warrant greater flexibility. Additionally, activities can be 
restricted dependent on the time of year and the location of the 
facility (e.g., due to seasonality, protected species, clearing 
restrictions). Because the groundwater monitoring requirements build 
upon each other, EPA must ensure that facilities nationwide are 
reasonably able to achieve regulatory compliance by the deadline. 
Utilizing a single deadline for the groundwater monitoring requirements 
allows facilities to make reasonable accommodations for regional 
factors in a way the proposed deadlines do not, while still maintaining 
the same level of protection for human health and the environment. 
Furthermore, EPA agrees that the proposed rule does not have a clear 
mechanism for facilities to prove compliance or for interested parties 
to verify compliance with the separate deadlines for the installation 
of the groundwater monitoring network and the development of the 
groundwater sampling and analysis plan.
    As stated in Unit III.C.4.a, EPA recognizes that the proposed CCRMU 
deadlines did not provide sufficient time for the completion of the FER 
and therefore extended the deadline for the completion of the FER by 24 
months as detailed in Unit III.C.3.c. The FER informs the owner or 
operator of the presence or absence of CCRMU at the facility, which is 
vital information for the completion of the groundwater monitoring 
system requirements (i.e., design and installation of the groundwater 
monitoring system). As such, the deadline for the groundwater 
monitoring requirements must be extended as well to allow owners or 
operators time to locate CCRMU as part of the FER. Furthermore, EPA was 
convinced that the deadlines for compliance with the legacy CCR surface 
impoundments and CCRMU requirements should be offset to mitigate 
impacts mentioned by commenters regarding the current labor shortages 
and backlogs experienced by third-parties necessary to accomplish tasks 
involved in complying with the groundwater monitoring requirements 
(e.g., drillers for well installation, laboratories for sample 
analysis) and the need for owners or operator of inactive facilities to 
first determine if there are legacy CCR surface impoundments onsite. 
Finally, based on the above-mentioned factors and the information 
provided by commenters, specifically the information regarding the 
suspected underestimation of the CCRMU universe due to historic 
facility-wide placement of non-containerized CCR on land, time needed 
to obtain necessary approvals (e.g., State permits to drill water wells 
or clear vegetation), and to accommodate for seasonality, EPA has 
calculated 18 months as the appropriate extension of the groundwater 
monitoring system deadlines for the latest groundwater monitoring 
requirement. In the proposed rule, the latest proposed deadline for 
groundwater monitoring requirements was the deadline of 24 months from 
the effective date of this final rule for the initiation of the 
combined detection and assessment monitoring and the collection of the 
eight baseline samples. Therefore, EPA is finalizing a single deadline 
of no later than 42 months after the effective date of this final rule 
for the groundwater monitoring requirements found at Sec. Sec.  257.90 
through 257.95.
i. Design and Installation of the Groundwater Monitoring System for CCR 
Management Units
    EPA proposed that owners or operators of CCRMU install the 
groundwater monitoring system as required by Sec.  257.91 no later than 
six months from the effective date of this final rule. EPA further 
proposed that existing monitoring wells can be used as a part of the 
CCRMU groundwater monitoring systems provided the wells meet the 
Federal criteria. As explained in the proposed rule, based on the 
amount of time most facilities needed to complete or to collect 
baseline sampling, EPA calculated that facilities would be able to 
install the necessary monitoring wells within a single year.
    As mentioned earlier, some commenters supported the expedited 
deadlines. However, most commenters stated the proposed deadline of six 
months from the effective date of the final rule for the design and 
installation of the groundwater monitoring network was infeasible and 
should be extended to no less than 24 months from the effective date to 
align with the 2015 rule deadline. As explained above, many of these 
commenters expressed the need for a single deadline for groundwater 
monitoring requirements. Furthermore, as described in Unit III.C.4.a of 
this preamble, these commenters cited seasonality restrictions, the 
nationwide labor shortages, limited qualified contractor availability, 
the need for State approvals and permits, and the number of facilities 
competing for limited resources as reasons for why the proposed 
expedited deadline is infeasible. A few commenters noted that in recent 
decisions on Part A demonstrations, EPA cited deficiencies in the 
groundwater monitoring network as a basis for noncompliance. These 
commenters went on to state that the proposed deadline does not 
facilitate the establishment of a monitoring system that would meet the 
standards laid out in the CCR rule or the recent proposed decisions and 
thus, the proposed deadline creates de facto non-compliance. Some of 
these commenters elaborated by saying that the deadline does not allow 
facilities to acquire the permits that may be required to drill wells 
and precludes the observation of groundwater levels over time, which is 
needed to properly characterize groundwater flow. Other commenters 
stated meeting the proposed compliance deadline would prevent a 
facility from conducting proper site characterization, which is needed 
to inform well placement and depth and providing P.E.s sufficient 
information to certify the groundwater monitoring system. Lastly, 
commenters stated that contrary to EPA's assertion in the proposed rule 
that expediting the installation of the groundwater monitoring network 
is protective of human health and the environment, to meet the proposed 
deadline, facilities would likely be forced to design groundwater 
monitoring systems based on inadequate data resulting in unreliable 
groundwater monitoring data. Commenters provided estimates of time 
needed to comply with the design and installation of the groundwater 
monitoring system requirements ranging from nine to 36 months.
    As stated in Unit III.C.4.a of this preamble, in response to 
comments EPA reevaluated the compliance deadline for the design and 
installation of the groundwater monitoring network and found the 
information provided regarding the general infeasibility of the 
proposed deadline compelling. Specifically, EPA agrees that more time 
is needed to allow inactive facilities time to determine if a legacy 
CCR surface impoundment is online prior to complying with the CCRMU 
requirements and to account for limited third-party availability (e.g., 
contractor shortages and laboratory backlogs), seasonality and extreme 
weather events, procuring a contractor, complying with

[[Page 39064]]

overlapping regulatory requirements, and coordinating with outside 
parties. EPA acknowledges the importance of proper site 
characterization as the foundation for designing a groundwater 
monitoring system and is convinced that although there may be some 
facilities that have adequate information for site characterization, 
many of these facilities, especially inactive facilities, may need to 
conduct more extensive site reconnaissance and field work to obtain the 
necessary information due to the widespread use of non-containerized 
CCR across facilities. EPA further recognizes that groundwater 
monitoring systems designed using inadequate data would be unable to 
properly monitor groundwater quality coming from the unit and therefore 
would not be protective of human health and the environment. Lastly, 
because EPA is convinced by information from the commenters that 
facilities would be unable to conduct all the steps necessary to design 
and install a groundwater monitoring system capable of meeting the 
standards in Sec.  257.91 by the proposed deadline, EPA has extended 
the deadline.
    As stated in Unit III.C.4.c, based on information provided by 
commenters, EPA concluded that a single deadline of 42 months from the 
effective date of this final rule should be used for the groundwater 
monitoring requirements. Therefore, EPA is finalizing a deadline for 
the completion of the design and installation of the groundwater 
monitoring system of no later than Monday, May 8, 2028, which is 42 
months from the effective date of this final rule. This is codified in 
the regulatory text at Sec.  257.90(b)(3)(i).
    To complete the installation of the groundwater monitoring system, 
the owner or operator of a CCRMU must ensure the monitoring system 
consists of sufficient number of wells both upgradient and downgradient 
of the CCR unit, installed at appropriate locations and depths, to 
yield groundwater samples from the uppermost aquifer that accurately 
represent the quality of background groundwater and groundwater passing 
the downgradient waste boundary of the CCR unit, monitoring all 
potential contaminant pathways. 40 CFR 257.91(a)(1) through (2). 
Because hydrogeologic conditions vary so widely from one site to 
another, the regulations do not prescribe the exact number, location, 
and depth of monitoring wells needed to achieve the general performance 
standard. Rather the regulation requires installation of a minimum of 
one upgradient and three downgradient wells, as well as any additional 
monitoring wells necessary to achieve the general performance standard 
of accurately representing the quality of the background groundwater 
and the groundwater passing. See, 80 FR 21399. The number and placement 
of the monitoring wells is critical to proper characterization of the 
groundwater. Thus, the specific number, spacing, and depth of the 
monitoring wells must be determined based on site-specific information, 
including but not limited to the thorough characterization of aquifer 
thickness, groundwater flow rate, groundwater flow direction throughout 
seasonal and temporal fluctuations, the unit's geological setting, and 
the unit's hydrogeological setting.
    The monitoring wells must be cased, constructed, operated, and 
maintained in a way that preserves the integrity of the monitoring well 
borehole, screened interval and other components so as to ensure the 
well performs to the design specifications throughout the life of the 
monitoring system. EPA expects owners or operators to ensure the 
groundwater monitoring wells are adequately protected from activities 
that may damage the wells or otherwise adversely impact their 
performance, such as accidental damage caused by livestock, vehicles, 
machinery, or other activities near the unit.
    The owner or operator of the unit must ensure that the design, 
installation, development, and decommissioning of any aspect of the 
groundwater monitoring system is thoroughly documented and included in 
the operating record. Furthermore, the owner or operator must obtain a 
P.E. certification or approval from the Participating State Director or 
EPA stating the groundwater monitoring system meets the standards set 
out in Sec.  257.91.
ii. Development of the Groundwater Sampling and Analysis Plan for CCR 
Management Units
    EPA proposed to require owners or operators of CCRMU to comply with 
the existing groundwater sampling and analysis program requirements for 
CCR units, including the selection of the statistical procedures that 
will be used for evaluating groundwater monitoring data. 40 CFR 257.93. 
EPA proposed a deadline of no later than six months after the effective 
date of the final rule for owners or operators to comply with this 
requirement.
    One commenter suggested EPA prohibit use of intrawell groundwater 
data comparisons for CCRMU. This commenter stated that intrawell 
comparisons are only appropriate when the background samples are 
collected before CCR was placed in the unit and therefore, since these 
units are likely already contaminating groundwater, they would be 
ineligible for intrawell data comparisons. Other commenters requested 
EPA allow alternative groundwater monitoring requirements, such as 
alternative groundwater sampling procedures and statistical analysis 
because of the inability to collect groundwater samples unaffected by 
CCR at some facilities due to the number of CCRMU at the site. As 
stated in Unit III.C.4.c, the existing groundwater monitoring and 
corrective action requirements are essentially the same requirements 
that have been applied to both hazardous waste and municipal solid 
waste disposal units for decades, and with the one exception discussed 
below, there is nothing about CCRMU that makes them distinct enough to 
warrant separate or additional requirements. Furthermore, while EPA 
expects many CCRMU have leaked or are potentially leaking, the 
commenter did not provide any evidence for creating a prohibition 
against intrawell data comparisons. Therefore, EPA will not be 
finalizing a prohibition on intrawell data comparisons at CCRMU. 
However, EPA acknowledges that since the 2015 CCR Rule went into 
effect, intrawell groundwater data comparisons have been misused to a 
large degree. Regarding the commenter who stated that the owner or 
operator would be unable to accurately represent background groundwater 
quality due to the potential extensive presence of CCRMU across the 
facility, during implementation of the 2015 CCR Rule, EPA has not found 
a situation in which representing background groundwater quality was 
impossible nor does EPA believe such a situation exists, as owners or 
operators are allowed to collect samples as far upgradient as needed, 
even offsite, to ensure that the groundwater sample is not impacted by 
CCR. Additionally, at Sec.  257.91(a)(1), EPA allows the owner or 
operator to collect background groundwater samples at other 
representative wells when hydrogeologic condition do not allow the 
determination of what wells are hydraulically upgradient wells or when 
other wells are more representative of background groundwater quality 
than upgradient wells. Furthermore, the commenter's assertion relied 
solely on the exhaustive presence of CCRMU at the facility as evidence 
of the inability to represent background water quality and did not 
provide any factual basis to support their claim that the requirement 
to

[[Page 39065]]

establish background groundwater quality as part of the groundwater 
monitoring requirements is infeasible. EPA is therefore finalizing this 
provision without revision. This is codified in the regulatory text at 
Sec.  257.90(b)(3)(ii).
    EPA received several comments on the proposed deadline for the 
development of the groundwater sampling and analysis plan. As mentioned 
in Unit III.C.4.c, some commenters supported the expedited deadline. 
However, several other commenters pointed out that the sampling and 
analysis plan cannot be completed prior to the collection of the 
baseline samples, which had a proposed deadline of 24 months from the 
effective date. Many of these commenters went on to state that the 
proposed expedited deadline for the development of the sampling and 
analysis plan could result in too frequent sampling leading to non-
independent, autocorrelated baseline samples for a large number of 
facilities, undermining the required statistical analysis. A few 
commenters further stated that EPA published decisions on Part A and 
Part B demonstrations citing lack of statistical independence in 
sampling as a basis for non-compliance, and failure for EPA to extend 
the deadline for the sampling and analysis plan to allow adequate time 
for facilities nationwide to gather independent samples would create de 
facto non-compliance.\143\ Commenters also said that the proposed 
deadlines do not account for the backlogs already experienced due to 
the existing CCR units using the small number of laboratories qualified 
to conduct the specialized analyses required by the rule, coupled with 
the national labor shortages. The commenters predicted the backlogs 
with laboratories will only increase with the regulation of legacy CCR 
surface impoundments and CCRMU, making the proposed deadlines even more 
infeasible. Finally, as mentioned in Unit III.C.4.c, commenters 
emphasized the need for one deadline for all groundwater monitoring 
requirements.
---------------------------------------------------------------------------

    \143\ On January 25, 2023, EPA proposed determinations on six 
Part B applications for alternate liner demonstrations (``Part B''). 
All six proposals are proposed denials. The CCR Part B Final Rule 
(85 FR 72506, November 12, 2020), allowed a limited number of 
facilities to demonstrate to EPA or a Participating State Director 
that, based on groundwater data and the design of a particular 
surface impoundment, the unit has and will continue to ensure there 
is no reasonable probability of adverse effects to human health and 
the environment.
---------------------------------------------------------------------------

    EPA agrees that a sampling and analysis plan cannot reasonably be 
completed before the collection of baseline samples. EPA also 
acknowledges the adverse impact of too frequent sampling on the 
validity of statistical analysis and the need to account for seasonal 
variability in groundwater flow, groundwater levels, and constituent 
concentrations. EPA further acknowledges that providing insufficient 
time for the collection of baseline samples or the development of the 
sampling and analysis plan would likely result in ineffective 
groundwater monitoring programs that may fail to alert facilities to 
groundwater contamination coming from CCR units. As explained in Unit 
III.C.4.a and Unit III.C.4.c respectively, EPA recognizes the need for 
more time to accommodate third-party availability and a single deadline 
for the groundwater monitoring requirements. As stated in Unit 
III.C.4.c.i, for the reasons laid out above, EPA is finalizing a single 
deadline for the groundwater monitoring requirements of no later than 
Monday, May 8, 2028, which is 42 months from the effective date of this 
final rule. This is codified in the regulatory text at Sec.  
257.90(b)(3)(ii).
    The owner or operator must develop the groundwater sampling and 
analysis program that satisfies the requirements in Sec.  257.93 and 
includes a list of monitoring wells to be sampled (i.e., the monitoring 
network), the schedule for sampling, sampling procedures and 
techniques, sample preservation and shipping protocols, analytical 
procedures including an appropriate statistical method for analysis, 
and quality assurance and quality control methods. The sampling and 
analysis plan must include all analytes listed in Appendix III and 
Appendix IV. Recommendations and information on how to comply with many 
of the requirements for the groundwater sampling and analysis program 
(e.g., analytical procedures, QA/QC controls, sampling protocol) can be 
found in the following EPA guidance documents (e.g., RCRA Groundwater 
Monitoring: Draft Technical Guidance, 1992, EPA/530/R-93/001; Low-Flow 
(Minimal Drawdown) Ground-Water Sampling Procedures, 1996, EPA/540/S-
95/504).
iii. Detection Monitoring Program and Assessment Monitoring Program 
Combined
    EPA proposed to require sampling and analysis of constituents 
listed in Appendix IV at the same time as those listed in Appendix III. 
The proposed rule explained that this would expedite groundwater 
monitoring and initiation of corrective action by at least six months 
at sites where units have potentially been leaking for a long period of 
time, as is likely the case at CCRMU. The proposed rule further 
explained that the expediting Appendix IV constituent detection and any 
resulting corrective action is necessary for the protection of human 
health and the environment. EPA proposed no other revisions to the 
existing groundwater monitoring requirements in Sec. Sec.  257.90 
through 257.95.
    EPA received several comments on its proposal to combine detection 
and assessment monitoring. One commenter pointed out the increased 
demand on laboratory services, facility staff and/or contractors, and 
professional engineers that would result from having CCRMU comply with 
both monitoring programs simultaneously. Another commenter stated that 
by combining detection and assessment monitoring and assuming 
groundwater contamination, EPA has rendered detection monitoring 
superfluous. Further, the commenter asserted that skipping detection 
monitoring entirely would lose critical data regarding whether there 
are statistically significant increases in groundwater constituents 
specifically due to the unit being monitored. One commenter stated that 
EPA lacked the record demonstrating risk posed by CCRMU to warrant 
combined detection and assessment monitoring and should either maintain 
the approach in the existing regulations or only apply groundwater 
monitoring to those CCRMU that have been identified as a source of an 
SSI or SSL in an ASD. Another commenter said that the justification in 
proposed rule regarding phased groundwater monitoring being ``best 
suited to situations where there is little likelihood of pre-existing 
contamination'' conflicts with EPA's position in the 2015 CCR Rule. 
According to the commenter, in the 2015 CCR Rule, the Agency was aware 
many CCR surface impoundments were decades old and potentially leaking; 
yet EPA still adopted a phased approach with detection monitoring to 
monitor indicators of potential groundwater contamination and 
assessment monitoring to determine if releases of CCR constituents of 
concern did occur.
    As a practical matter, EPA expects combining Appendix III and 
Appendix IV constituents into a unified sampling and analysis plan and 
approach will likely have only minor effects on schedules, as this 
change will not require additional field mobilizations or sampling 
events and will only require collection of a slightly larger number of 
sample containers at each monitoring well to allow for analysis for 
both Appendix III and IV constituents. As such, no additional shipments 
of

[[Page 39066]]

samples to the analytical laboratory will be required. However, EPA 
acknowledges that combining Appendix III and Appendix IV constituents 
into a unified sampling and analysis plan may increase the total 
throughput burden on analytical laboratories and related services. 
Similarly, while combined monitoring may require additional evaluation 
(e.g., concentration and trend analysis of data concerning both 
Appendix III and Appendix IV constituents), this incremental increase 
is unlikely to significantly increase the overall reporting level of 
effort, as the number of reports will be essentially unchanged.
    Nevertheless, as discussed in Units III.C.4.a and III.C.4.c of this 
preamble, EPA acknowledges the commenters' concerns regarding existing 
and projected labor shortages, backlogs, and third-party availability, 
and agrees this has the potential to affect facilities' ability to 
comply with the proposed deadlines for groundwater monitoring 
requirements. EPA is therefore extending the deadline, as well as 
building in flexibility for facilities to accommodate for delays, by 
finalizing a single deadline for groundwater monitoring requirements in 
lieu of the proposed split deadlines.
    However, EPA disagrees that combining detection and assessment 
monitoring will render detection monitoring redundant, and that 
critical data would be lost, by sampling for Appendix IV constituents 
at the same time as Appendix III constituents (i.e., by collecting more 
information). The commenters provided no further explanation of what 
information they thought would be lost, but under the combined 
monitoring, the facility would collect the same information on Appendix 
III constituents that is collected under the detection monitoring in 
Sec.  257.94. Given that under the existing assessment monitoring 
provisions, facilities must simultaneously analyze samples for all 
parameters in Appendix III and for any Appendix IV constituent detected 
in the initial sampling, it is not apparent why the commenter believes 
that requiring simultaneous monitoring more broadly is appreciably 
different. 40 CFR 257.95(d)(1).
    As stated in the previous paragraph, concurrent monitoring for 
Appendix III and Appendix IV constituents provides considerably more 
information and enables a more complete understanding of the 
geochemical nature, fate, and transport of any detected releases. 
Additionally, simultaneously collecting samples for Appendix III and 
Appendix IV constituents will still provide the basis for determining 
SSIs, should they exist, so no information will be lost. Contrary to 
the commenter's concern, additional information will be gained in an 
expedited manner (e.g., the potential spatial and temporal correlation 
of Appendix III SSIs with exceedances of SSLs for Appendix IV 
constituents). Furthermore, EPA disagrees that its explanation that 
phased groundwater monitoring is ``best suited to situations where 
there is little likelihood of pre-existing contamination'' 
fundamentally conflicts with EPA's decision to adopt phased monitoring 
in the 2015 CCR Rule. Unlike this rule, the 2015 CCR Rule applied to 
both new facilities, which would be expected to have little likelihood 
of pre-existing contamination, and to existing facilities. Over the 
long-term, EPA expected that there would eventually be a greater 
percentage of new units than existing units as the older units reached 
capacity and closed. In addition, as discussed in the proposal at 88 FR 
32010 and in Unit III.A.2 of this preamble, it is clear from the data 
posted on facilities' websites that in 2015 EPA significantly 
underestimated the number of unlined units (both impoundments and 
landfills), and consequently, significantly underestimated the number 
of leaking units and the extent of contamination at these sites.
    Under the phased approach in the current regulations, detection 
monitoring was intended to provide an early detection of whether 
groundwater was potentially being contaminated. In selecting the 
parameters for detection monitoring, EPA chose constituents present in 
CCR that would be expected to move rapidly through the subsurface and 
thus provide an early detection of a potential problem before 
significant releases of constituents of greatest concern (i.e., those 
in Appendix IV) had occurred. This approach rests on a presumption that 
the unit is not already leaking and the record shows (see Unit III.C.1) 
that presumption is largely inappropriate for CCRMU.
    If an alternate source is causing an exceedance of an Appendix III 
constituent, it may also be the source of any SSL detected for any 
Appendix IV constituents; in such a case, a facility may simply prepare 
a single ASD that covers constituents from both appendices. The sole 
difference between phased monitoring and combined monitoring is if the 
alternate source is only responsible for the Appendix III constituent, 
but the unit actually is releasing one or more Appendix IV 
constituents. In such a case, under a phased approach detection of the 
Appendix IV constituent can be delayed or even remain undetected, 
because the facility would not trigger assessment monitoring absent an 
SSI from another Appendix III constituent. In such situations, combined 
monitoring can make the monitoring program more accurate; it is unclear 
why the commenter believes this is inappropriate.
    Ultimately, the combined monitoring expedites the initiation of 
assessment monitoring which in turn, allows for more expeditious 
identification of statistically relevant exceedances of Appendix IV 
constituents. This will in turn expedite ASD development or corrective 
action, depending on the circumstances.
    The phased approach in the 2015 CCR Rule provides for a graduated 
response to groundwater contamination as the evidence of contamination 
increases over time. This approach allows facilities ample time to 
investigate the source of contamination as well as the transport 
characteristics of CCR constituents in groundwater, while usually being 
protective of human health and the environment. However, at sites where 
there is a strong likelihood that groundwater contamination has been 
occurring for a long time, the advantages provided by a protracted 
graduated response are outweighed by disadvantages of persistent or 
even increasing contamination that continues to move downgradient. At 
these sites, the need to protect human health and the environment 
necessitates the quick detection of Appendix IV constituents of concern 
to expedite any necessary corrective action. See, USWAG, 901 F.3d at 
427-30. In this case, as highlighted in Unit III.A, the record provides 
strong reason to conclude that many CCRMU are contaminating 
groundwater, given the large number of currently regulated CCR units 
that have been found to be leaking.
    Therefore, EPA is finalizing this requirement as proposed to be 
completed no later than Monday, May 8, 2028, which is 42 months after 
the effective date of this final rule. This is codified in the 
regulatory text at Sec.  257.90(b)(3)(iv) and (v).
iv. Collection and Analyses of Eight Independent Samples for CCR 
Management Units
    EPA proposed that no later than 24 months after the effective date 
of the final rule, owners or operators of CCRMU initiate the detection 
monitoring program by completing sampling and analysis of a minimum of 
eight independent samples for each background and downgradient well, as

[[Page 39067]]

required by Sec.  257.94(b). The proposed rule explained that within 90 
days after initiation of the detection monitoring program, owners or 
operators must identify any SSIs over background levels for the 
constituents listed in Appendix III, as required by Sec.  257.94. To 
expedite the time to initiate any required corrective action, EPA also 
proposed that by this same deadline owners or operators initiate the 
assessment monitoring program by establishing groundwater protection 
standards and by starting to evaluate the groundwater monitoring data 
for an SSL over GWPS for the constituents listed in Appendix IV as 
required by Sec.  257.95.
    EPA is finalizing this requirement as proposed. This is codified in 
the regulatory text at Sec.  257.90(b)(3)(iii).
    EPA received several comments on the proposed deadline for the 
collection of the eight baseline samples. As mentioned in Unit 
III.B.2.a.ii, some commenters supported the expedited deadline. 
However, several other commenters requested that the groundwater 
monitoring requirement deadlines be combined into a single deadline 
that provided at least as much time to come into compliance as was 
provided in the 2015 CCR Rule deadlines (i.e., 24 months after the 
effective date of the final rule). As stated in Unit III.C.4.c, based 
on information provided by commenters, EPA concluded that a single 
deadline of 42 months after the effective date of this final rule 
should be used for the groundwater monitoring requirements. Therefore, 
EPA is finalizing a deadline for the completion of sampling and 
analysis of a minimum of eight independent samples for each background 
and downgradient well of no later than Monday, May 8, 2028, which is 42 
months from the effective date of this final rule.
v. Preparation of Initial Groundwater Monitoring and Corrective Action 
Report for CCR Management Units
    EPA proposed to apply the existing requirements in Sec.  257.90(e) 
to CCRMU and require that owners or operators of CCRMU comply no later 
than January 31 of the year following the calendar year after a 
groundwater monitoring system has been established (and annually 
thereafter).
    One commenter suggested that the initial groundwater monitoring and 
corrective action report be due no later than January 31 of the year 
following the collection of the eight baseline samples and the first 
semi-annual sampling event in order to allow facilities to provide all 
the documentation required by Sec.  257.90(e). EPA disagrees that the 
information required by Sec.  257.90(e) would not be available to a 
facility upon completion of the groundwater monitoring system, as the 
annual report serves as an update on the activities related to the 
groundwater monitoring program, including the installation of 
groundwater monitoring wells. Additionally, when specific actions are 
not required by the CCR regulations (e.g., a facility has not triggered 
corrective action), facilities are not out of compliance merely because 
they do not have activities related to that action to discuss in the 
groundwater monitoring and corrective action annual report (e.g., not 
describing progress in selecting a remedy when not in corrective 
action).
    EPA is finalizing the requirement for owners or operators of CCRMU 
to comply with the requirements in Sec.  257.90(e), which mandate the 
preparation of an annual groundwater monitoring and corrective action 
report no later than January 31, 2029 and annually thereafter. This is 
codified in the regulatory text at Sec.  257.90(e).
    The report documents the activities associated with the groundwater 
monitoring program and progress of any corrective action over the past 
year and must contain specific information identified in the 
regulations, including but not limited to maps; aerial images or 
diagrams showing the CCRMU and all upgradient (background) and 
downgradient wells; identification of any monitoring wells installed or 
decommissioned in the previous year; monitoring data collected under 
Sec. Sec.  257.90 through 257.98; and a narrative discussion of any 
transition between monitoring programs (i.e., detection and assessment 
monitoring). The annual reporting requirement will help ensure that 
groundwater level data collected over the reporting period is 
tabulated, presented, and analyzed to determine groundwater levels 
relative to any residual CCR left in place as well as to confirm or 
determine groundwater flow directions.
    Upgradient and downgradient well locations and depths should be 
validated annually with respect to measured and mapped flow directions. 
Groundwater quality sampling data should be included in appendices and 
summarized and tabulated in the annual reports. If appropriate, 
exceedances (SSIs and SSLs) of Appendix III and IV constituents should 
be tabulated and highlighted. As mentioned in some comments, annual 
reports should identify the nearest downgradient surface water bodies 
as well as groundwater supply wells in the vicinity of the unit.
    It is critical that annual corrective action and monitoring reports 
provide the basis for selection and documentation of corrective actions 
as early as possible. The owner or operator must not only document 
compliance in the annual report, but also post the annual report on the 
public CCR website to allow the public to review the groundwater 
monitoring results. It is critical that the annual reports contain the 
basic data which informs the positions and status reported in those 
documents, including but not limited to boring logs, monitoring well 
installation diagrams, water level data, field sampling data sheets for 
groundwater sample collection, laboratory analytical data including QA/
QC data, data validation, etc. In summary, the annual groundwater 
monitoring and corrective action reports should not only contain the 
information required by the regulations but should be organized in such 
a way that: (1) Compliance with the CCR regulations is evident; (2) 
Data supporting compliance conclusions are easily located within the 
document; and (3) The public is readily able to review the groundwater 
monitoring data and related information. Lastly, the name of the 
document on the public CCR website should be such that it is clear what 
the file is and it must be capable of being readily printed and 
downloaded by the public.
vi. Corrective Action Requirements for CCR Management Units
    EPA proposed to require owners or operators of CCRMU to comply with 
the existing corrective action criteria, as appropriate in Sec. Sec.  
257.96 through 257.98. The proposed rule explained that conducting the 
sampling simultaneously would expedite groundwater monitoring and, 
where necessary, initiation of corrective action by at least six months 
at sites where units have potentially been leaking for a long period of 
time, as is likely the case at many CCRMU. The proposed rule further 
explained that expediting Appendix IV constituent detection, assessment 
and any required corrective action would protect human health and the 
environment.
    Under the existing regulations, if groundwater monitoring 
demonstrates an exceedance of the groundwater protection standards for 
constituents identified in Appendix IV of part 257, corrective action 
is required, as laid out in Sec. Sec.  257.96 through 257.98. These 
requirements apply throughout the active life and any post-closure care 
period of the CCR unit.

[[Page 39068]]

    A commenter suggested EPA create a deadline for the completion of 
the selection of remedy required by Sec.  257.97 of 90 days after the 
completion of the assessment of corrective measures (ACM) with the 
ability to extend the deadline up to 180 days after the completion of 
the ACM. The commenter pointed to the failure of owners and operators 
of units regulated by the 2015 CCR Rule to select a remedy as soon as 
feasible after the completion of the ACM as required by the rule and 
the subsequent unnecessary delay in addressing contaminated 
groundwater. Other commenters stated that applying the existing 
groundwater monitoring and corrective action requirements to historic 
sites, such as CCRMU, is not appropriate and suggested that instead EPA 
incorporate site-specific risk-based corrective action or State 
corrective action programs into the CCR regulations. Finally, some 
commenters requested EPA adopt a RCRA subtitle C approach and utilize 
existing EPA guidance. One of these commenters further stated that the 
application of the existing CCR corrective action requirements conflict 
with EPA's decision-making frameworks in other programs such as RCRA 
and CERCLA due to lack of site-specific risk assessments to evaluate 
risk and drive corrective action decisions. This commenter suggested 
that EPA utilize site-specific, risk-based corrective action that is 
consistent with the guidance documents EPA has developed for RCRA and 
CERCLA programs.
    EPA acknowledges the widespread non-compliance with the mandate to 
complete the selection of remedy as soon as feasible after the 
completion of the ACM. However, EPA disagrees with the commenter's 
suggested deadline for two reasons. First, the recommended deadline 
extends the deadline for the completion of the selection of remedy 
beyond that in 2015 CCR Rule since ``as soon as feasible'' in many 
cases would likely be before 90 days after the completion of the ACM 
and granting owners or operators more time to select a remedy would be 
less protective of human health and the environment. Second, EPA is 
taking action to address the non-compliance related to the failure of 
owner or operators to select a remedy as soon as feasible as part of 
the EPA's National Enforcement and Compliance Initiative and expects 
this enforcement initiative to address the concern raised by the 
commenter.\144\
---------------------------------------------------------------------------

    \144\ EPA Enforcement Alert, National Enforcement and Compliance 
Initiative, Protecting Communities from Coal Ash Contamination. EPA 
Document #310F23002. December 2023. https://www.epa.gov/system/files/documents/2023-12/ccr-enf-alert-2023.pdf.
---------------------------------------------------------------------------

    EPA disagrees with the suggestion that existing corrective action 
requirements, if triggered, are inappropriate at CCRMU. As stated in 
Units III.A and III.C.4.d, the physical characteristics and potential 
risks of CCRMU are not sufficiently different from currently regulated 
units to justify different requirements. For those commenters 
requesting that EPA adopt ``risk-based corrective action'' into the 
requirements, EPA notes that the commenters have provided no further 
explanation of what requirements in the existing regulations they 
wanted EPA to revise, what the revisions should accomplish, or why such 
revisions are necessary or appropriate. As a general matter EPA 
considers that the corrective action regulations in Sec. Sec.  257.95 
through 257.98 do currently require facilities to tailor remedies to 
address the risks to human health and the environment, based on the 
conditions at the site. It is unclear what more the commenters are 
seeking. Additionally, regarding incorporating or allowing State 
corrective action programs to substitute for the existing corrective 
action requirements, the commenters failed to demonstrate through 
factual or specific information that the State corrective action 
programs referenced are either different than that required by the CCR 
regulations or adequate to address the risks posed by CCRMU. Even if 
individual examples were sufficient to overcome the record with respect 
to State programs generally, none of the examples presented by the 
commenters provided sufficient detail for EPA to actually evaluate the 
adequacy of the corrective action programs. More to the point, EPA 
lacks the record necessary to support a broad exemption for all CCRMU 
conducting corrective actions under any State requirements. Regarding 
comments requesting a RCRA subtitle C approach be adopted for CCRMU, a 
RCRA subtitle C approach is more appropriate for regulation under a 
permitting program than under the existing regulatory framework (i.e., 
self-implementing) and as explained in Units III.A and III.C.1, EPA 
finds the risks posed by CCRMU to be not only credible but significant 
enough to warrant regulation at this time (i.e., under the self-
implementing rule as opposed to waiting until the Federal permitting 
program is established). Lastly, the commenter that stated that the 
existing corrective action regulations conflict with other EPA programs 
(i.e., RCRA and CERCLA) failed to fully explain how the existing 
corrective action regulations conflict with EPA-published RCRA or 
CERCLA guidance documents or how they preclude corrective action 
decisions driven by site-specific risks. Accordingly, EPA is 
finalizing, without revision, its proposal that CCRMU comply with the 
existing corrective action requirements at Sec. Sec.  257.95 through 
257.98.
    As explained in the proposed rule at 88 FR 32003, Sec. Sec.  257.90 
through 257.95 require that an owner or operator of a CCR unit to 
install a system of monitoring wells, specify procedures for sampling 
these wells, and set forth methods for analyzing the groundwater data 
collected to detect hazardous constituents (e.g., toxic metals) and 
other monitoring parameters (e.g., pH, total dissolved solids) released 
from the units (i.e., all parameters listed in Appendices III and IV). 
If the groundwater monitoring required in Sec.  257.95, demonstrates an 
exceedance of the groundwater protection standards for constituents 
identified in Appendix IV of part 257, corrective action is required as 
laid out in Sec. Sec.  257.96 through 257.98. These requirements apply 
throughout the active life and post-closure care period of the CCRMU.
    When corrective action is required, it must be initiated without 
delay, in accordance with the time frames laid out in the regulations. 
The corrective action program includes initiating an ACM to prevent 
further releases, to remediate any releases, and to restore affected 
areas to original conditions, as specified in Sec.  257.96(a). After 
the ACM has been completed, the owner or operator must select a remedy 
that meets prescribed standards, including a requirement that the 
remedy attain the groundwater protection standards. See Sec.  257.97(a) 
and (b). Finally, the corrective action program requires the owner or 
operator of the CCR unit to initiate remedial activities within 90 days 
of selecting a remedy. See Sec.  257.98(a). The requirement to address 
releases under this requirement is identical to those requirements for 
any CCR unit undertaking groundwater corrective action with the 
additional requirement that implementation of corrective action begin 
during the active life of the unit.
    EPA expects that when assessing corrective measures and selecting a 
remedy, the owner or operator of the unit will consider the impact of 
the corrective measures on the water quality and safety of the nearest 
surface water bodies and the nearest private and/or public groundwater 
wells.
    With respect to completion of an ACM and remedy selection, Sec.  
257.96(a) requires an ACM be initiated within 90

[[Page 39069]]

days of determining an SSL has occurred, and then completed within 
another 90 days. An extension, not to exceed 60 days, may be warranted 
due to site-specific conditions or circumstances. Prior to closure of a 
CCR unit, the facilities have been required to characterize site 
conditions, including groundwater flow conditions and geology. The 
facilities have knowledge of the wastestreams and water volumes it 
discharges to CCR units. This information can be used to develop a 
groundwater model to predict groundwater flow conditions after waste 
stream disposal ceases and closure is initiated. Therefore, EPA 
believes this would provide sufficient characterization of post-closure 
conditions to assess and compare groundwater cleanup alternatives to 
complete an ACM.
    Once the ACM is complete, a public meeting has been held, and 
community input has been considered, a remedy must be selected as soon 
as feasible. A selected remedy may include closure by removal to comply 
with source control requirements. This would constitute commencing 
implementation of a remedy. However, the selected groundwater 
remediation portion of the remedy must also be implemented within a 
reasonable time, in accordance with the schedule established in the 
remedy selection report. 40 CFR 257.97(d). Implementation of the source 
control measure does not negate this requirement.
d. Closure and Post-Closure Care Criteria for CCR Management Units
    EPA proposed that all of the existing closure and post-closure care 
requirements in Sec. Sec.  257.101 through 257.104 would apply to 
CCRMU, except for the alternative closure requirements in Sec.  
257.103(f). EPA further explained that the alternative closure 
provisions in Sec.  257.103(f) were not appropriate for CCRMU as these 
units, by definition, are inactive impoundments at inactive facilities 
and could not therefore demonstrate the need to continue to use the 
disposal unit, which is a qualifying component of the alternative 
closure provisions. In addition, EPA solicited comments on two 
potential revisions to the existing closure standards in Sec.  
257.102(d). The first potential revision would extend the existing 
dewatering requirement in Sec.  257.102(d)(2)(i) to any CCR landfill 
constructed in groundwater or otherwise saturated by liquids. The 
second potential revision would incorporate a definition of the term 
``infiltration'' into Sec.  257.102.
    EPA also proposed to require that all CCRMU initiate closure within 
12 months of the effective date of this final rule. While EPA proposed 
that the CCR unit closure requirements would apply, EPA also solicited 
comment on other approaches to how a facility might implement the 
requirement to close at a site where the CCRMU lies beneath an 
operating unit.
    Finally, EPA proposed to apply the existing post-closure care 
requirements in Sec.  257.104 to CCRMU. Each of these proposals and the 
comments are discussed in detail below.
    EPA received numerous comments on its proposal to apply the 
existing closure and post-closure care requirements Sec. Sec.  257.100-
257.104 to CCRMU. Several commenters stated that EPA must require all 
CCRMU to close, because the risks EPA identified in the proposal, 
together with information provided by regulated facilities under the 
2015 CCR Rule, indicate that CCRMU pose significant and ongoing threats 
of contamination if not properly closed. These commenters also 
identified several examples of units that the commenters believe 
demonstrate the need for CCRMU to close. One commenter referenced a 
report it submitted to support EPA's proposal to regulate CCRMU. The 
report focuses on six sites with both CCR units currently regulated by 
the CCR Rule and with CCRMU. According to the commenter the report 
documents significant and harmful coal ash pollution that has been 
allowed to persist under the 2015 CCR Rule and that would be remediated 
under the proposed rule.

For example, the report analyzes the Brandywine Ash Management 
Facility in Maryland, which has a single landfill that its operator 
GenOn has treated as four distinct CCR dumpsites for purposes of the 
CCR Rule. This artificial division of the landfill has enabled GenOn 
to claim that three of the four areas of the landfill are 
unregulated under the CCR Rule; to attribute contamination at the 
site, such as molybdenum levels eighty times above the GWPS, to the 
three purportedly unregulated areas; and to keep the site in 
detection monitoring through ASDs. The Proposed Rule will compel 
GenOn to address all coal ash at the site.
Another site that demonstrates the necessity of regulating CCRMU 
under the Proposed Rule is the Joliet #29 Station owned by Midwest 
Generation in Illinois. This site has one regulated pond, Ash Pond 
2, and a number of additional units that would be treated as CCRMU 
under the Proposed Rule. In fact, the site was used for coal ash 
disposal long before it had a power plant, potentially as early as 
1917, indicating the presence of unlined landfills going back 
decades. Midwest Generation has found statistically significant 
increases (``SSIs'') for TDS, sulfates, chloride, and calcium at the 
site, but is only monitoring the groundwater around Ash Pond 2 and 
two former ash ponds, and not monitoring the groundwater around 
three large onsite landfills.

These commenters also described a facility where, according to the 
commenters, two million tons of fill containing CCR sits behind 
corroding steel pilings on the shore of Lake Michigan, and is leaking 
arsenic and other hazardous chemicals into the lake, as well as into an 
adjacent creek commonly used for fishing and boating. These commenters 
also pointed to a facility with an inactive 90-acre unlined CCR 
landfill that, according to the commenter, is contaminating groundwater 
with unsafe levels of sulfate, lithium, radium, cobalt, arsenic, 
molybdenum and selenium. Similarly, a private citizen also provided the 
following example of a potential CCRMU during one of public hearings:

My utility is City Utilities. Once the current coal ash landfill is 
full, CU plans to dispose of future coal ash at a temporarily closed 
landfill next to Lake Springfield, which feeds into the James River. 
Both dumps are in karst terrain. This makes them susceptible to 
sinkhole collapses and leakage of pollutants into the James River 
watershed and the area's shallow and deep aquifers. These waters 
affect a four-state area, including Table Rock Lake near Branson 
where tourism is the main industry. Safer methods of disposal exist, 
although they are more cumbersome and expensive, In December 2022, 
CU held a public meeting regarding the utility's future. After 
questions about pollution, one representative said he wasn't aware 
of any pollutants coming from the landfill. The Interdisciplinary 
Environmental Clinic at Washington University School of Law 
researched this. Twelve rounds of sampling done by CU from late 2016 
to early 2018 showed 387 statistically significant increases in 
pollutants in every down-gradient well. Those increases included 27 
out of the 35 monitored parameters. Regarding CU's dye tests at the 
dump site, a 2017 memo from the Missouri Department of Natural 
Resources stated, ``Dye is moving through the karst system and not 
being detected by the monitoring well network.''

These commenters also pointed to the high likelihood that many CCRMU 
have waste in contact with groundwater, as many are located in 
floodplains, wetlands, or near large rivers and lakes. According to the 
commenters, if EPA does not mandate closure of CCRMU, aquifer 
contamination would not be identified until it is too late to be 
prevented--in contravention of RCRA's protectiveness standard. These 
commenters have also argued that CCRMU are inactive units with no 
practical justification to avoid closure.
    A number of other commenters however argued that a national 
requirement to close was not appropriate for CCRMU and that EPA should 
instead determine whether

[[Page 39070]]

closure is warranted at each site based on a finding that the 
individual unit at that particular site poses unacceptable risks. Many 
of these commenters suggested that the risks associated with CCRMU can 
be better managed through corrective action implemented under a permit 
program, which the commenters believed would make the mandate to close 
these units unnecessary. For example, one commenter claimed that 
mandating the closure of all CCRMU as part of the proposed CCR 
corrective action regime is more stringent than what EPA requires under 
subtitle C for solid waste management units (SWMUs), and therefore any 
final CCRMU rule cannot impose a mandatory closure requirement on 
CCRMU. According to this commenter, the subtitle C process does not 
require the closure of SWMUs, because EPA recognizes that addressing 
the risks from SWMUs via the site-specific subtitle C corrective action 
process alone is fully protective. Many commenters also raised concern 
that CCRMU at their facilities are located beneath vital 
infrastructure, such as pipelines or transmission lines, active CCR 
units, or buildings and that requiring closure of these CCRMU could 
adversely impact grid reliability, business operations, or other 
necessary public services (e.g., military infrastructure). These 
commenters suggested that EPA exempt these units or at least extend the 
closure time frames to allow for closure of the CCRMU when the other 
unit or structure is closed or decommissioned.
    Numerous commenters again requested that EPA exempt any CCRMU that 
had been closed in accordance with State requirements. These commenters 
claimed that these closures were protective and that EPA should only 
regulate these CCRMU where the Agency has affirmative evidence that the 
particular unit is contaminating groundwater or otherwise presents 
unacceptable risks. For example, one commenter stated that a more 
rational approach to regulating CCRMU would be first to determine if 
the uses are impacting groundwater before requiring expensive closure. 
According to the commenter,

[i]t is not clear why EPA requires closure before groundwater data 
indicates there is a problem. If groundwater is impacted by the 
CCRMU then other corrective action measures should be taken, but 
only after data indicates that groundwater is being affected. As 
noted earlier, the 2015 CCR Rule did not require unlined landfills 
to close unless they failed to meet the location restrictions for 
unstable areas. In the event an unlined CCR landfill is the source 
of groundwater contamination, the unit is subject to the CCR Rule's 
corrective action requirements, but closure is not mandatory.

    But many other commenters characterized the proposed deadline as 
infeasible for the reasons discussed in Unit III.B.2.a.ii, including 
seasonality, the need to comply with overlapping regulatory 
requirements, labor shortages, and the limited resources available to 
achieve compliance (e.g., contractors, laboratories, P.E.s), which the 
commenters claimed would become even more limited as a consequence of 
the number of CCR units that would need to come into compliance at the 
same time. Commenters also stated that compliance with the closure 
requirements should not be required until after the groundwater 
monitoring system was installed and baseline samples collected so that 
closure could be informed by the groundwater monitoring data.
    EPA has largely adopted the proposal, with a few significant 
revisions. This final rule requires CCRMU that contain 1,000 tons or 
greater of CCR to comply with the existing closure and post-closure 
care requirements in Sec. Sec.  257.101 through 257.104, except for the 
alternative closure requirements in Sec.  257.103(f). The final rule 
also extends the existing dewatering requirement in Sec.  
257.102(d)(2)(i) to any CCR landfill constructed in groundwater or 
otherwise saturated by liquids, and incorporates a definition of the 
term ``infiltration'' in Sec.  257.53.
    However, consistent with the provision adopted for legacy CCR 
surface impoundments, EPA is deferring, in certain cases, the 
requirement to demonstrate compliance with Sec.  257.102 for CCRMU that 
closed prior to the effective date of this rule in accordance with 
alternative requirements that are likely to be as protective as the 
requirements in Sec.  257.102. This is the same provision that EPA is 
establishing for legacy CCR surface impoundments, as EPA is not aware 
of a reason to treat CCRMU differently. In addition, EPA is deferring 
the requirement to initiate closure where the CCRMU is located beneath 
critical infrastructure or large buildings or structures vital to the 
continuation of current site activities, such as beneath high power 
electric transmission towers, air pollution control or wastewater 
treatment systems, large buildings, or an electrical substation. In 
this case, the potential exists for adverse, localized impacts on 
electric reliability (e.g., voltage support, local resource adequacy) 
from requiring all facilities to meet these requirements on the same 
time frame, and EPA lacks the record to determine that such impacts are 
unlikely. Consequently, EPA is deferring the requirement to initiate 
closure of such a CCRMU until the infrastructure is no longer needed, a 
permit authority determines closure is necessary to ensure that there 
is no reasonable probability of adverse effects on human health or the 
environment, or the closure or decommissioning of the facility, 
whichever occurs first.
    Finally, EPA has extended the deadline to initiate closure to 
Wednesday, November 8, 2028, which is 48 months the effective date of 
the final rule to allow groundwater monitoring data to inform closure, 
consistent with the approach for legacy CCR surface impoundments.
    Each of these issues are discussed in greater detail in subsequent 
sections of this preamble.
i. Requirement To Initiate Closure
    The final rule requires CCRMU containing 1,000 tons or greater of 
CCR to close. Closure will address the existing risks associated with 
these units. In addition, requiring the closure of CCRMU is consistent 
with the existing regulations, which require closure of all units that 
no longer receive waste as a preventative measure, whether or not the 
unit is currently leaking. See, 40 CFR 257.102(e)(1). CCRMU, which 
consist of inactive CCR landfills and previously closed CCR surface 
impoundments and CCR landfills, meet these criteria as they also no 
longer receive waste.
    The closure of CCRMU of 1,000 tons or greater also provides 
significant risk mitigation. As laid out in Unit III.A of this 
preamble, CCRMU at both active facilities and inactive facilities with 
legacy impoundments pose risks to human health and the environment that 
are at least as significant as the risks presented by legacy CCR 
surface impoundments and the units currently regulated under the 2015 
CCR Rule. In particular, for highly exposed individuals off site, 
landfill CCRMU were estimated to pose cancer risks as high as 7 x 
10-6 from arsenic III, while surface impoundment CCRMU were 
estimated to pose cancer risks as high as 8 x 10-5 from 
arsenic III and noncancer HQs as high as two for arsenic III, two for 
lithium, and one for molybdenum. Differences in national risks between 
currently regulated units and these older units are attributed largely 
to the proportion of units that were modeled at the time as lined. 
However, the risks associated with these older units may be even higher 
than EPA modeled in the 2014 Risk Assessment for active units. These 
units have been present onsite

[[Page 39071]]

longer and had more time to leak. In addition, there are several 
management practices that have the potential to result in higher 
leakage, but that were previously modeled either less frequently for 
active units--based on a belief that the practices had declined over 
time--or not at all--due to data constraints on a national scale. These 
include: (1) The greater prevalence of unlined units; (2) The greater 
likelihood of co-management of CCR with coal refuse and other wastes in 
surface impoundments, making the overall waste pH far more acidic and 
(3) The potential for the units to be constructed below the water table 
or to have become inundated with groundwater after the time of 
construction. As discussed in Unit III.A, each of these practices 
individually have the potential to result in nationwide risks higher 
than previously reported on a national basis for the currently 
operating universe of CCR units. For example, unlined landfill CCRMU 
were estimated to pose cancer risks as high as 1 x 10-5 from 
arsenic III, while unlined surface impoundment CCRMU were estimated to 
pose cancer risks ranging from 2 x 10-4 from arsenic III and 
noncancer HQs as high as 5 for arsenic III, 3 for lithium, 2 for 
molybdenum, and 1 for thallium. A combination of these practices could 
push risks even higher than modeled.
    In addition, the modeling conducted in 2024 confirms that smaller 
CCRMU fills can meaningfully contribute to groundwater contamination 
across a facility. The 90th percentile concentrations at the waste 
boundary exceeded GWPS by factors of 26 for arsenic III, 19 for arsenic 
V, 156 for molybdenum, and 19 for thallium. The 50th percentile 
concentrations exceeded GWPS by a factor of two for molybdenum. EPA's 
modeling also confirms that any prior contamination from CCRMU is 
likely to still be present. EPA calculated, for example, that it could 
take around 2,300 years from the time of first exceedance for high-end 
releases of arsenic V to fully dissipate.
    Depending on their location, leakage of Appendix IV constituents 
from individual CCRMU fills may not migrate off-site at levels of 
concern. However, according to the commenters it is highly unlikely 
that only one CCRMU would be present on-site. In addition, these 
concentrations can combine with contamination from other CCRMU, 
currently regulated CCR units, or legacy CCR surface impoundments that 
are also present on the same site. EPA did not model the aggregate or 
cumulative risk associated with these potential sources of co-located 
contamination, which may underestimate the risks. At a minimum, EPA 
expects that the presence of multiple sources of potential 
contamination at the same facility would increase the likelihood of a 
contaminant plume that could migrate off-site at levels of concern. In 
sum, the record confirms that, at a minimum, regulation of the smaller 
sized CCRMU fills is necessary for any corrective action to 
successfully reduce the concentrations of Appendix IV constituents in 
the aquifer to concentrations below the GWPS.
    Available toxicological profiles indicate that ingestion of arsenic 
is linked to increased likelihood of cancer in the skin, liver, bladder 
and lungs, as well as nausea, vomiting, abnormal heart rhythm, and 
damage to blood vessels; ingestion of lithium is linked to neurological 
and psychiatric effects, decreased thyroid function, renal effects, 
cardiovascular effects, skin eruptions, and gastrointestinal effects; 
and ingestion of molybdenum is linked to higher levels of uric acid in 
the blood, gout-like symptoms, and anemia. 80 FR 21451. To date, 
groundwater monitoring required by the 2015 CCR Rule has revealed that 
at least 40% of currently regulated surface impoundments and landfills 
have identified groundwater contamination and require corrective action 
to mitigate the associated risks. This number is expected to increase 
as more facilities come into compliance with the groundwater monitoring 
requirements. Another 23% of existing CCR units have identified 
evidence of leakage and continue to monitor groundwater to ensure that 
contamination does not occur before the unit can be closed and source 
controls put in place. In many cases, CCRMU are historical landfills 
and surface impoundments. Thus, the relevant release pathways, exposure 
routes, and associated harm that can result are the same.
    Given the locations of many CCRMU (located in floodplains, or 
wetlands, or near large surface water bodies), EPA is also concerned 
that the base of these units may intersect with the groundwater beneath 
the unit. If such CCRMU were not required to close, EPA would not 
adequately address the risks from those units that still contain CCR 
saturated with free liquids.
    In general, EPA considers that closure is the only effective way to 
adequately address the source of potential or existing releases from 
these units. Although, as some commenters suggested, EPA could rely 
upon the existing corrective action requirements to achieve source 
reduction, the Agency is concerned that this will not adequately 
prevent harm, as the statute requires, because these requirements would 
only apply upon a determination that the CCRMU has contaminated the 
aquifer above the GWPS. In addition, the closure requirements in Sec.  
257.102 provide a uniform approach that EPA is confident will 
adequately protect human health and the environment.
    Contrary to the commenter's contentions the regulation of CCRMU 
under RCRA section 4004(a) is not analogous to the corrective action 
requirements applicable to SWMUs under RCRA section 3004(u). Nor is the 
absence of a national mandate to close SWMUs as part of every 
corrective action under section 3004(u) based on the recognition that 
closure is unnecessary because the corrective action process alone is 
fully protective. The closure and corrective action regulations are 
distinct and independent requirements that generally serve different 
purposes. The closure requirements under both subtitle C and D are 
largely intended to be prevent contamination from occurring in the 
first place, by ensuring that the closed unit does not become a source 
of future contamination. See, e.g., 47 FR 32318, 32321, 32323. By 
contrast, corrective actions are remedial or retrospective in that they 
are designed to clean up contamination that has already occurred. EPA 
has previously promulgated regulations mandating the closure of 
disposal units for wastes under both subtitles C and D for wastes 
within each subsection's jurisdiction. See, 40 CFR 264, subpart G, 258, 
subpart F. But the requirement for corrective action of solid waste 
management units under the provisions applicable to hazardous wastes 
under section 3004(u) is an anomaly; Congress has otherwise limited 
subtitle C to the regulation of hazardous wastes. The appropriate 
comparison is thus not to EPA's regulation of SWMUs under subtitle C, 
but rather to EPA's regulation of hazardous waste units under subtitle 
C, where the Agency requires hazardous waste units to comply with both 
closure and corrective action requirements.
    In sum, the record demonstrates that closure is warranted for 
CCRMU, even for those that are not yet leaking. As the D.C. Circuit 
explained, RCRA requires EPA to set minimum criteria for sanitary 
landfills that prevent harm, not merely to ensure that contamination is 
remediated. See, USWAG, 901 F.3d at 430.
    Consistent with the requirements for legacy CCR surface 
impoundments, EPA is not requiring previously closed CCRMU to 
automatically re-close but simply to evaluate whether the unit

[[Page 39072]]

meets the requirements of Sec.  257.102(d), and if they do not, to take 
such measures as are necessary to bring the unit into compliance.
ii. Deferral for CCRMU Under Critical Infrastructure
    As noted above, many commenters stated that some CCRMU are 
currently located beneath critical infrastructure. For example, a 
number of commenters stated that CCR has historically been used on-site 
at generating stations for many years as structural fill, including for 
utility line bedding, and under site infrastructure such as 
switchyards, coal piles, railroad embankments, and occupied buildings. 
Additionally, commenters pointed to many areas at their existing 
facilities with CCR currently located under existing critical energy 
infrastructure such as generating units, cooling towers, substations, 
levees, dikes, on-site wastewater treatment systems, dams, transmission 
towers, gas lines, and solar installations.
    These commenters claimed that requiring closure of CCRMU beneath 
infrastructure could adversely impact grid reliability, business 
operations, or other necessary public services and suggested EPA create 
exemptions or extensions for these units. According to these 
commenters, attempting to close any of these areas under the rule's 
closure standards would not only be impossible, but also would require 
disturbing and/or even disassembling critical components of power 
plant's energy infrastructure, which would only further exacerbate the 
pressures on grid reliability. Other commenters raised concern that 
remediation would require removal of existing infrastructure to access 
the CCR, which in some cases could present significant operational risk 
and potential danger. As one commenter characterized it,

Particularly at active power plants, requiring closure of CCRMU . . 
. would cause massive ripple effects that need to be more carefully 
considered. Closure would be incredibly disruptive for these type of 
sites--particularly given the inadequate time for electricity 
resource planning--and exacerbate the grid reliability challenges 
that co-ops and other utilities are already facing. Moreover, EPA 
must consider and allow for power plant owners to follow the 
mandated procedures put in place by the relevant balancing 
authority, such as regional transmission organizations or electric 
utilities, and by state authorities which have a role in ensuring 
the reliability of the local grid.

    Several commenters also expressed concern about the closure of 
CCRMU located under active CCR landfills, asserting that such closures 
pose complex challenges that EPA did not fully understand or account 
for in the proposed rule. Many of these commenters asserted that these 
closed landfill or surface impoundment CCRMU present no risks. For 
example, one commenter discussed a closed surface impoundment located 
beneath its active CCR landfill. The commenter asserted that the 
permitted, Federally regulated CCR landfill above the closed unit, 
combined with the collective effect of the CCR landfill liner and 
leachate collection system, runoff controls, and engineered cap, keeps 
the impoundment isolated from exposure to stormwater runoff and other 
sources of water infiltration. The commenter further asserts that there 
is no evidence that this former impoundment is impounding or otherwise 
contains any significant amount of free liquids, and that such a 
condition is unlikely given the overlying landfill infrastructure.
    By contrast, numerous commenters supported the proposed mandate to 
close due to the substantial risks that these kinds of ``overfill'' 
units can pose. As one of these commenters explained,

In this situation the underlying CCRMU serves the function of the 
foundation of the overlying CCR unit. The liner of the overlying CCR 
unit serves as a cap over the underlying CCRMU. CCR contaminants 
released from either the overlying CCR unit or underlying CCRMU can 
adversely impact groundwater quality with little potential for 
distinguishing between contaminants released from one or the other 
of these units. Each of the co-located units must be capable of 
containing CCR contaminants if releases to the environment are to be 
avoided.
Construction of a CCR unit over a previously existing CCRMU is known 
to have the potential to increase concentrations of CCR groundwater 
contaminants. A 2001 study by the Electric Power Research Institute 
(EPRI) showed that reducing the hydraulic gradient beneath a CCR 
impoundment can induce increased contaminant concentrations when the 
waste is in contact with groundwater. EPRI concluded that reducing 
the hydraulic gradient by dewatering an impoundment slowed 
groundwater flow and increased contact time between the waste and 
groundwater. Contact time between waste and water is an important 
variable that influences concentrations of contaminants found in 
groundwater.
Release of contaminants from the overlying unit, while possible, is 
not necessary to cause increasing contaminant concentrations. The 
bottom liner of the overlying CCR unit reduces infiltration of water 
from above, reducing the hydraulic gradient and increasing waste/
water contact time. The increased contact time can increase 
contaminant concentrations in downgradient monitoring wells.

The commenters acknowledged that where the waste in the CCRMU is dry 
and the owner/operator can assure that separation of the waste from 
water (groundwater and/or infiltration from above) will be maintained 
the unit may be closed in place under the CCR rule without posing 
ongoing risks. The commenter also noted, however, that where unlined 
waste units are continually or periodically in contact with 
groundwater, more extensive closure techniques such as engineering 
controls designed to prevent groundwater from flowing through waste or 
to stabilize the waste and fix contaminants in place may be attempted, 
or excavation and clean closure of the unit may ultimately be 
necessary.

    Unlike the comments received on legacy CCR surface impoundments, 
the overwhelming majority of commenters provided concrete examples of 
concerns with respect the timing of closure activities for to CCRMU. In 
total, these commenters have provided sufficient information to raise a 
legitimate question whether adverse, localized impacts on electric 
reliability (e.g., voltage support, local resource adequacy) could 
result from a nationwide requirement to close all CCRMU within the 
deadlines under the regulations.
    EPA agrees that closing CCRMU underlying critical infrastructure at 
active generating facilities is very different and more challenging 
than closing disposal units at inactive utilities. When it was 
developing the proposal, EPA was unaware of the extent to which 
facilities had historically used CCR as part of the foundation 
supporting generating units, cooling towers, substations, or on-site 
wastewater treatment systems. In some cases, it appears that in order 
to close these CCRMU individual facilities may need to disturb 
substantial portions of the entire site and disassemble critical 
components of the power plant's energy infrastructure, such as high 
power electric transmission towers, and electrical substations.
    EPA agrees that its proposal did not adequately account for this 
circumstance. This is particularly true in the case of a CCRMU located 
beneath infrastructure necessary for energy production, where the 
potential exists for adverse, localized impacts on electric reliability 
(e.g., voltage support, local resource adequacy). This issue arises 
whenever multiple facilities need to take their EGU offline for an 
extended period to complete construction or other compliance 
activities. The likelihood of an adverse impact on electric reliability 
can be greater if multiple facilities need to schedule outages 
simultaneously in order to comply with EPA's closure deadlines. EPA 
understands that it is

[[Page 39073]]

also possible that in some instances temporarily taking generating 
units (including coal-fired units) offline could have an adverse, 
localized impact on electric reliability (e.g., voltage support, local 
resource adequacy). If a generating asset were needed for local 
reliability requirements, the grid operator might not approve a request 
for a planned outage. In such instances, the owners/operators of the 
generating unit could find themselves in the position of either 
operating in noncompliance with RCRA or halting operations and thereby 
potentially causing adverse reliability conditions. In addition, 
failure of an electric transmission or generation system can lead to 
substantial risks to human health (e.g., if an outage impairs the 
ability of emergency services to function properly or it causes home 
heating or cooling systems to fail, which increases risk, particularly 
for vulnerable populations).
    However, such impacts are far less likely to arise from an 
individual facility-specific decisions, and should normally be 
adequately managed by the established RTO processes for scheduling 
outages. EPA recognizes that this final rule provides a substantial 
amount of time for facilities to complete these closures. In contrast 
with the proposal, the final rule provides facilities 54 months to 
initiate closure, and depending on the CCRMU, the facility may have as 
much as an additional seven to 15 years to complete closure. Based on 
the comments, however it appears that the overwhelming majority of 
CCRMU below critical energy production infrastructure are likely to be 
landfills, and therefore the seven year deadline is more likely to be 
applicable.
    Further, this situation is not analogous to the closure of unlined 
and clay lined impoundments in response to the USWAG vacatur, and thus 
the information used to develop the deadline for those CCR units in the 
Part A rule cannot be used to develop a comparable requirement for 
these CCRMU. For example, there appear to be a greater number of CCRMU 
at these sites and the construction estimates EPA relied upon in 2020 
in the Part A final rule applied exclusively to the six specific 
technologies that a facility might use to develop alternative disposal 
capacity. That rulemaking did not involve the potential effect of 
disturbing substantial portions of the entire site or disassembling 
critical components of the power plant's energy infrastructure, such as 
high power electric transmission towers or electrical substations, 
which is what some commenters have alleged will be necessary in this 
case.
    Unfortunately, because EPA only became aware of these facts after 
development of the proposal the Agency has not had the time to obtain 
the information necessary to evaluate--or to consult with balancing 
authorities and other electric reliability authorities (e.g., DOE or 
NERC) on the feasibility of mandating closure of all CCRMU within these 
deadlines, within the time to complete this rulemaking.\145\
---------------------------------------------------------------------------

    \145\ EPA is obligated to take final action on the proposal no 
later than May 6, 2024, pursuant to Statewide Organizing for 
Community eMpowerment v. EPA, No. 1:22-cv-2562-JDB (D.D.C.).
---------------------------------------------------------------------------

    EPA acknowledges that the risks associated with CCRMU above the 
regulatory threshold are substantial, and generally warrant a mandate 
to close in accordance with Sec.  257.102. Moreover, the fact that EPA 
did not model the aggregate risks associated with the widespread use of 
small amounts of unencapsulated CCR throughout the entire facility 
raises questions about whether EPA may have underestimated the 
potential risks associated with these CCRMU. EPA also agrees that 
overfills can present significant risks, particularly when the closed 
CCR unit remains inundated by groundwater or otherwise continues to 
contain free liquids. EPA therefore concludes that exempting these 
CCRMU from the requirement to close in accordance with Sec.  257.102 is 
not appropriate.
    Given that EPA has the ability to rely on the permitting process to 
address issues on a case-by-case basis, and because doing so will allow 
the Agency to adequately address both the competing environmental and 
reliability risks presented at individual sites, it is reasonable for 
the Agency to choose this option. Consequently, EPA is deferring the 
requirement to initiate closure of CCRMU located beneath critical 
infrastructure until either: (1) The infrastructure is no longer 
essential for the activity to be successful; (2) A permit authority 
determines closure is necessary to ensure there will be no reasonable 
probability of adverse effect on health or the environment; or (3) The 
closure or decommissioning of the facility, whichever occurs first.
    The final rule also includes an additional condition on CCRMU under 
active disposal units. In order for these units to qualify for the 
deferral, the facility must document that the CCRMU meets one of two 
existing performance standards: either (1) The standard in Sec.  257.60 
that the unit was constructed with a base that is located no less than 
1.52 m (5 feet) above the upper limit of the uppermost aquifer, or must 
demonstrate that there is no intermittent, recurring, or sustained 
hydraulic connection between any portion of the CCR unit and the upper 
limit of the uppermost aquifer or surface water; or (2) The dewatering 
standard in Sec.  257.102(d)(2)(i) that all free liquids have been 
eliminated. EPA believes the location standard in Sec.  257.60 is 
likely to be more directly applicable to many CCRMU, as they are 
landfills that would not have been constructed or designed to hold free 
liquids. EPA has also included the dewatering standards in Sec.  
257.102(d)(2)(i) for those closed CCR surface impoundment CCRMU. Based 
on the descriptions provided by commenters EPA expects that this 
requirement will largely be relevant to closed CCRMU located beneath 
active disposal units, rather than CCRMU located beneath infrastructure 
vital to energy production, which are unlikely to be inundated by 
groundwater. Moreover, this requirement directly addresses the reason 
that EPA has concluded that many previously completed closures do not 
meet the standard in RCRA section 4004(a).
    To be clear, EPA is not exempting these CCRMU from the requirement 
to close as commenters requested, but merely extended the deadline for 
compliance until the Agency can address it on an individualized basis 
as part of permitting. In addition, these units will be required to 
comply with all other requirements applicable to CCRMU, including the 
requirements for groundwater monitoring and corrective action, if 
necessary.
    As noted above and discussed in the next section, in response to 
public comments, EPA has extended the deadline to initiate closure to 
Tuesday, May 8, 2029, which is 54 months after the effective date of 
this final rule. Based on its current schedule, EPA expects to be 
issuing permits before that deadline.
    EPA is defining ``critical infrastructure'' as infrastructure, 
large buildings, or other structures vital to the success or 
continuation of current site operations or activities for the public 
welfare. This does not include infrastructure, large buildings, or 
other structures that solely provide commercial or financial benefit to 
private entities. Examples of critical infrastructure include high 
power electric transmission towers, large buildings, and electrical 
substations. The structures must be both (1) necessary for the 
continued generation of power or currently used for an ongoing site 
activity; and (2) not readily replaced or relocated. For example, a

[[Page 39074]]

parking lot that could easily be replaced by a parking lot in a 
different location onsite would not qualify as critical infrastructure; 
but a lined industrial stormwater ponds, wind or solar farms, 
substations, or military infrastructure would qualify.
    The owner or operator of a CCRMU located under critical 
infrastructure must include information documenting their eligibility 
for the deferral in the FER part 2 in Sec.  257.75(d) that includes at 
a minimum a description of the infrastructure, its current and 
anticipated use(s), and the decommissioning date or anticipated active 
lifespan. The documentation must also demonstrate that the CCRMU 
complies with either Sec.  257.60 or Sec.  257.102(d)(2)(i). The 
documentation must also demonstrate that the structures are both: (1) 
Necessary for the continued generation of power or currently used for 
an ongoing site activity; and (2) Not readily replaced or relocated.
    When it comes time for a permit authority to evaluate the CCRMU, 
EPA intends to rely on the permit application process as the primary 
mechanism to collect the information to allow a determination to be 
made as to whether to require closure of the CCRMU prior to facility 
closure. The permit application process is a well-established system 
for reviewing the types of groundwater, soil and other sampling and 
analytical data that will typically be required in determining the 
potential risks associated with the CCRMU.
    When the permit application is called in, the facility must provide 
sufficient information, including data on contaminant levels in 
groundwater, to demonstrate that the criteria listed above for the 
deferral have been met, and for the permit authority to be able to 
evaluate the risks associated with the CCRMU. EPA (or other permit 
authority) will review the information to determine whether the 
criteria for deferral have been met and whether closure is necessary to 
mitigate unacceptable risks to human health or the environment from the 
CCRMU.
    Finally, EPA received a substantial number of comments requesting 
that the Agency not require facilities to ``re-close'' any unit that 
already completed closure. This final rule does not mandate that any 
previously closed unit automatically re-close. But as described in the 
next section, the final rule does require all CCRMU to meet the 
performance standards in Sec.  257.102, although as discussed above, 
some may not be required to do so until the permitting process begins 
for that unit. EPA does not consider this to be equivalent to a 
requirement to ``re-close'' as facilities may be able to implement 
engineering measures to address any deficits without removing the cover 
system or entirely re-closing the whole impoundment. Whether any 
particular measure will be effective is a site-specific determination, 
but some reasonably available engineering measures that may be 
effective and should be considered include the installation of physical 
barriers (e.g., slurry walls), groundwater diversion techniques (e.g., 
interception trench) or hydraulic containment systems (e.g., 
groundwater extraction wells) to prevent groundwater infiltration.
iii. Requirement To Comply With Performance Standards in Sec.  257.102
    As discussed above, this final rule requires that the closure of 
CCRMU meet the performance standards in either Sec.  257.102(c) or (d). 
Under this final rule all closures initiated after the effective date 
of this rule, as well as to those that were not completed prior to the 
effective date of this rule, will need to comply with these 
requirements.
    And in general, the same is true with respect to closures that were 
completed prior to the effective date of this rule. As discussed 
previously, a facility that can certify that prior closure of a unit 
meets the performance standards in Sec.  257.102(c) only needs to post 
the documentation that the closure meets the standard. Similarly, if a 
facility can demonstrate that the closed unit meets the requirements 
under Sec.  257.102(d), EPA will consider the unit to be closed and the 
only requirements that will be applicable are those that apply to 
closed units under post closure care--that is groundwater monitoring, 
and if necessary, corrective action. EPA never intended to require 
facilities that otherwise met the closure standards to go through the 
process again and re-close the unit. In addition, as discussed in the 
next section, where the facility was subject to standards that are 
different than the Federal CCR closure standards--e.g., if the closure 
was conducted as part of a CERCLA cleanup--but otherwise is equivalent 
in terms of mitigating the risks, the requirement to meet the Sec.  
257.102 standards will be deferred to permitting, where a closure 
equivalency determination will be made.
(a) Closure of CCRMU Under State Law and Deferral of Certain Completed 
Closures to Permitting
    In response to EPA's proposal that all CCRMU comply with Sec.  
257.102, many commenters requested that EPA exempt any unit that has 
either completed closure or is in the process of closing pursuant to 
State law (e.g., solid waste permit, consent orders or decrees). 
Commenters also requested that EPA exempt any site that closed as part 
of a cleanup conducted pursuant to another Federal requirement, such as 
CERCLA or RCRA subtitle C. For the most part, these commenters simply 
repeated the comments that they had made with respect to legacy CCR 
surface impoundments, stating that EPA had failed to demonstrate that 
these units posed any risk as a consequence of the lack of ponded 
water, and that ``re-closure'' of these previously closed units is 
consequently unnecessary and overly burdensome. However, several 
commenters also presented individual examples of CCRMU that had been 
closed in accordance with State requirements, which the commenters 
believed would demonstrate the State closures were equally as 
protective as those conducted in accordance with Sec.  257.102. These 
included the following examples:

[A facility] has an approximately 20-acre dry stack landfill with 20 
plus years of groundwater monitoring that does not show groundwater 
exceedances, zero potential receptors downstream (from the direction 
of groundwater) that use wells for drinking water (also no potable 
wells within a two-mile radius). The landfill construction using 
best practices to minimize erosion potential, including only 
placement of stabilized material in the landfill, perimeter ditch 
surrounding the entire landfill to collect any runoff that is 
processed before discharge, and the unit is regulated by the Florida 
Department of Environmental Protection that includes semi-annual 
groundwater monitoring results review and yearly on-site regulatory 
inspections.
[Another facility] had two CCRMU landfills that were closed prior to 
the effective date of the 2015 CCR Rule and were closed in 
accordance with the State of Florida's Chapter 62-701, F.A.C., for 
municipal and solid waste landfills. Neither landfill was built on 
top of a liner system. The closed landfills were subject to design 
criteria for cover systems and stormwater management, as well as 
long-term operations and maintenance provisions. The groundwater 
monitoring system requirements for landfills in Florida are similar 
to, but not the same as, those in the 2015 CCR rule. Both closed 
cells would be subject to corrective action if dictated by the 
monitoring program. Maintenance, inspections, and repair of the 
cover systems, as needed, are also part of the long-term care 
program.
[Another facility] reported closing an inactive CCR landfill in the 
1980s. The 20-acre site was used to dispose of bottom and fly ash, 
including scrubber sludge. The owner performed monitoring of a 
nearby spring to demonstrate whether any ponded water was leaking. 
Upon visual inspection, it was determined that the bentonite/clay-
lined pond remained intact throughout the active

[[Page 39075]]

operation of the landfill. However, because of the age of the site, 
groundwater monitoring wells were not required.

    In addition, several States provided information about their 
existing programs or individual closures. In some instances, the 
information was intended to demonstrate that the closures were equally 
as protective as Sec.  257.102, and to provide factual support for an 
exemption for CCRMU that closed in accordance with State requirements. 
Other States acknowledged the risks but urged EPA to make the CCRMU 
requirements ``more flexible and allow for practical alternatives to 
closure and corrective action for units that have not impacted 
groundwater,'' or to provide an opportunity to demonstrate if the 
previous closure of the CCRMU is protective of human health and the 
environment.
    By contrast, several commenters supported EPA's proposal to require 
all CCRMU to comply with the performance standards in Sec.  257.102, 
even if the closure was previously approved by a State regulatory 
agency. These commenters also largely made the same comments they had 
made with respect to legacy CCR surface impoundments, pointing to EPA's 
conclusions in 2015 that significant gaps remain in many State 
programs. These commenters also identified recent examples of closures 
approved by various State agencies that they believed were not 
consistent with the Federal closure standards.
    No commenter submitted any information that would support a 
conclusion that different provisions are warranted for CCRMU that 
closed prior to the effective date of this rule than EPA adopted for 
similarly situated legacy CCR surface impoundments. Even if individual 
examples were sufficient to overcome the record with respect to State 
programs generally, none of the examples presented by the commenters 
provided sufficient detail for EPA to actually evaluate the adequacy of 
the closures. For instance, in the three examples presented above, 
neither of the first two examples actually describe the groundwater 
monitoring that was required; while the second states that 
``groundwater monitoring system requirements for landfills in Florida 
are similar to, but not the same as, those in the 2015 CCR rule'' it 
provides no further information. The third example explains that no 
groundwater monitoring at all was required because of the age of the 
unit; it is unclear why the commenter believes that this supports a 
finding that the State program is as protective as those in part 257.
    More to the point, as EPA explained in Unit III.B.2.g of this 
preamble, with respect to legacy CCR surface impoundments, EPA lacks 
the record necessary to support a broad exemption for all CCRMU 
closures under any State requirement. The limited information currently 
available does not demonstrate that all closures conducted under State 
authority, particularly those completed prior to 2015, ``will ensure 
there is no reasonable probability of adverse effects on health or the 
environment.'' 42 U.S.C. 6944(a).
    EPA, however, agrees that there are examples of closures that are 
substantially equivalent to those conducted in accordance with Sec.  
257.102. Moreover, EPA has no basis for concluding that the same 
considerations that warrant deferral of certain legacy CCR surface 
impoundments closures are not equally applicable to comparable CCRMU 
closures. Accordingly, EPA is deferring the requirement for a CCRMU 
that closed prior to the effective date of this rule to demonstrate 
compliance with Sec.  257.102(d) until a permit application is required 
to be submitted where the facility can document that all of the 
following conditions have been met. First, the deferral is limited to 
circumstances in which a regulatory authority played an active role in 
overseeing and approving the closure activities. EPA considers a 
``regulatory authority'' to include a State or Federal agency or 
department that oversaw implementation of requirements imposed through 
a permit, an administrative order, or consent order issued after 2015 
under CERCLA or by an EPA-approved RCRA State program. The permit, 
order, regulatory or other authority must have required groundwater 
monitoring to ensure there was no contamination coming from the unit 
that is not addressed by corrective action until cleanup standards are 
achieved.
    To support deferral of a prior closure of a CCRMU as substantially 
equivalent, the facility must also document that the CCRMU meets one of 
two existing performance standards: either: (1) The standard in Sec.  
257.60 that the unit was constructed with a base that is located no 
less than 1.52 m (5 feet) above the upper limit of the uppermost 
aquifer, or must demonstrate that there is no intermittent, recurring, 
or sustained hydraulic connection between any portion of the CCR unit 
and the upper limit of the uppermost aquifer or surface water; or (2) 
The dewatering standard in Sec.  257.102(d)(2)(i) that all free liquids 
have been eliminated. This requirement directly addresses the reason 
that EPA has concluded that many previously completed closures do not 
meet the standard in RCRA section 4004(a).
    In addition, a facility must document that it had installed a 
groundwater monitoring system and performed groundwater monitoring that 
meets a subset of the performance standards found in Sec.  257.91(a). 
Specifically, the facility must demonstrate that the groundwater 
monitoring system was capable of: (1) Accurately representing 
background water quality, (2) Accurately representing the quality of 
water passing the waste boundary, and (3) Detecting contamination in 
the uppermost aquifer. The groundwater monitoring system must have 
monitored all potential contaminant pathways.
    Next, a facility would need to demonstrate that a site-specific 
risk assessment was conducted or approved by the regulatory authority 
prior to (or as part of) approving the closure, and that the closure 
and any necessary corrective action has been overseen by the regulatory 
authority, pursuant to an enforceable requirement.
    Finally, the facility would be required to prepare and include 
documentation in the applicability report and operating record, 
demonstrating that it has met these criteria and is eligible for 
deferral. The documentation must include specifics including the State 
permit, order, data, GWM results, etc. This must be certified by the 
owner/operator or an authorized representative using the same language 
in Sec.  257.102(e).
    When it comes time for the permit authority to evaluate the 
closure, EPA intends to rely on the permit application process as the 
primary mechanism to collect the information to allow a determination 
to be made as to whether a CCRMU that closed under these alternative 
standards did so in compliance with the requirements of Sec.  257.102. 
The permit application process is a well-established system for 
reviewing the types of groundwater, soil and other sampling and 
analytical data that will typically be required in determining the 
``equivalency'' of alternative closures.
    When the permit application is called in, the facility must provide 
sufficient information, including data on contaminant levels in ground 
water, to demonstrate that the applicable Sec.  257.102 standards have 
been met. EPA or an approved State Director (the permitting authority) 
will review the information to determine whether the ``equivalency'' of 
the closure has been successfully demonstrated. If EPA determines that 
the closure has met the

[[Page 39076]]

appropriate part 257 closure standard, EPA or an approved State 
Director will issue a post-closure permit. If EPA or an approved State 
Director determines that the closure does not meet the part 257 
standards, the owner or operator will be required to submit a permit 
application containing all the applicable information for an operating 
permit, and EPA will issue a permit that contains the specific 
requirements necessary for the unit to achieve compliance with Sec.  
257.102.
(b) Revisions to Performance Standards for Closing With Waste in Place
(1) Expansion of Sec.  257.102(d)(2)(i) to CCR Landfills
    Given the locations of many CCRMU (located in floodplains, or 
wetlands, or near large surface water bodies), EPA is concerned that 
the base of these units may intersect with the groundwater beneath the 
unit. As EPA has previously explained, where the base of a surface 
impoundment intersects with groundwater, the facility will typically 
need to include engineering measures specifically to address any 
continued infiltration of groundwater into the impoundment in order to 
close with waste in place consistent with Sec.  257.102(d). See, e.g., 
87 FR 72989 (November 28, 2022), 85 FR 12456, 12464 (March 3, 2020). 
The same holds true for CCRMU that intersect with groundwater. The 
existing requirements in Sec.  257.102(d)(1) and (3) apply to all CCR 
units and EPA proposed that these provisions would also apply to CCRMU 
without revision. By contrast, the existing requirements in Sec.  
257.102(d)(2), which establish performance standards for drainage and 
stabilization of the unit, only apply to CCR surface impoundments. 
These performance standards are critical to ensuring that units that 
contain liquids are properly and safely closed, and therefore should 
apply to any unit, including a CCRMU and a CCR landfill, where free 
liquids remain in the unit. Accordingly, EPA proposed to revise Sec.  
257.102(d)(2) so that it applies to all CCR units and CCRMU. To assist 
commenters, the proposal included a background discussion of the 
existing closure performance standards. Finally, EPA explained that if 
there are no liquids in the unit, the proposed revision would not 
require the facility to do anything to meet the performance standards.
    Several commenters supported the proposed revision. For example, 
one commenter provided data about an unlined CCR landfill that was 
constructed above the groundwater table and was found to be ``impacting 
groundwater with high concentrations of heavy metals, with particularly 
high concentrations of boron fluctuating between 14 and 30 mg/L.'' The 
State of Michigan required closure of this landfill due to groundwater 
impacts and after the landfill completed closure, ``the boron 
concentrations returned to background concentrations approximately five 
years later.'' The commenter further went on to state, ``this example 
is provided to demonstrate that any type of water contact with CCR 
disposal areas can impact groundwater, causing concentrations to rise 
to concerning levels above water quality standards.'' Another commenter 
suggested that, consistent with its statement in the proposal, EPA 
should further revise Sec.  257.102 to clarify that the performance 
standards are met if there is no liquid in the CCRMU. The commenter 
recommended the following revisions to Sec.  257.102(d)(1) and (2):

(1) General performance standard. The owner or operator of a CCR 
unit or CCR management unit that contains liquid must ensure that, 
at a minimum, the CCR unit or CCR management unit is closed in a 
manner that will: * * *
(2) Drainage and stabilization of CCR units and CCR management 
units. The owner or operator of any CCR unit or CCR management unit 
that contains liquid must meet the requirements of paragraphs 
(d)(2)(i) and (ii) of this section prior to installing the final 
cover system required under paragraph (d)(3) of this section.

    A few commenters opposed extending Sec.  257.102(d)(2) to CCR 
landfills and CCRMU, asserting that EPA had failed to provide a factual 
basis to justify the revision. For example, one commenter stated that:

There are two purposes for free liquids removal--addressing 
stability and potential groundwater contamination. For long-closed 
units, stability is demonstrably not a concern. For groundwater, any 
potential contamination can be addressed through corrective action 
rather than closure. . . . EPA does not explain why the existing 
corrective action regulations--which would require corrective action 
and potentially source control in the event groundwater contact 
causes impacts to groundwater--are insufficient. In short, the 
proposed extension of the requirements is unnecessary and 
unsupported by the record.

Another commenter contested the factual basis for the ``proposed rule's 
assumption'' that CCR are in contact with groundwater. According to the 
commenter, CCR surface impoundments and CCR landfills are not located 
in the same hydrogeological environments and requires a site-specific 
evaluation to determine, which is beyond the requirements of the 
existing CCR regulations. One commenter criticized EPA for failing to 
identify the 19 landfills ``already regulated under the 2015 CCR final 
rule, but which have waste in contact with groundwater,'' and depriving 
the public of an opportunity to comment on the accuracy of that 
proposed finding. Another commenter said it takes a very long time to 
eliminate free liquids in a CCRMU or landfill, which typically happens 
during post-closure care.

    EPA disagrees that it has failed to justify the revision. The 
proposed rule did not rest on an assumption but on information (e.g., 
annual groundwater monitoring and corrective action reports, closure 
plans) posted to facility CCR websites showing that the bases of their 
CCR landfills are in contact with groundwater. EPA has included a list 
of these facilities in the docket for this final rule. In addition, 
other commenters have provided further examples of landfills that are 
submerged in the aquifer. Moreover, while the commenter is correct that 
whether groundwater is infiltrating a particular unit is a site-
specific determination, the commenter failed to provide any factual 
basis for its assertion that CCR surface impoundments and CCR landfills 
are never located in the same hydrogeological environments. And 
contrary to the commenter's assertion EPA has repeatedly explained why 
it is insufficient to rely on corrective action rather than closure to 
address the risks associated with CCR landfills. The closure and 
corrective action regulations are distinct and independent 
requirements, each of which must be met. The closure in-place standards 
are designed to ensure that the waste in the closed unit has been dried 
out and is kept dry so that leachate cannot form in the closed unit and 
subsequently be released to the environment. See, e.g., 47 FR 32318, 
32321, 32323. For impoundments that are not yet leaking compliance with 
these provisions are largely designed to ensure that the closed unit 
does not become a source of future contamination. In other words, the 
closure standards are expressly designed to prevent groundwater 
contamination. By contrast, the corrective action provisions in 
Sec. Sec.  257.96 through 257.98 contain the standards and procedures 
for cleaning up the contamination in the groundwater that has already 
leaked out of the unit. See, e.g., 40 CFR 257.97(b)(2) and (4) 
(requiring that clean up remedies ``attain the groundwater protection 
standard [in] Sec.  257.95(h)'' and ``remove from the environment as 
much of the contaminated material as was released

[[Page 39077]]

from the CCR unit as feasible''). See, USWAG, 901 F.3d at 429-430, 431.
    EPA appreciates the commenter's suggested alternative regulatory 
text; however, EPA is concerned that the suggested revision is 
effectively redundant of the new definition of ``contains CCR and 
liquids'' and would not clearly communicate the entities that are 
subject to the regulation. Therefore, EPA is finalizing this 
requirement as proposed. In addition, because it can take a significant 
amount of time to meet the performance standards in Sec.  
257.102(d)(2), EPA has extended the closure deadlines applicable to any 
CCR landfill that needs to meet these standards.
(2) Definition of Infiltration
    EPA requested comment on whether to adopt a regulatory definition 
of the term ``infiltration,'' consistent with term's plain meaning and 
the dictionary definitions discussed in the preamble.
    Several commenters agreed that EPA should adopt a regulatory 
definition of infiltration that explicitly recognizes the myriad ways 
that liquids can infiltrate CCR surface impoundments. Some commenters 
supported EPA's proposed definition of ``infiltration'' because 
industry has argued that ``the presence of groundwater in ash ponds is 
essentially irrelevant to closure compliance and that the CCR Rule's 
closure in place requirements are limited to draining the surface 
portion of the pond, constructing a final cover, and preventing surface 
water--but not groundwater--infiltration thereafter.'' Another 
commenter stated EPA should define ``infiltration'' to make clear that 
it is ``a general term that refers to the migration or movement of 
liquid into or through a CCR unit from any direction, including the 
top, sides, and bottom of the unit.''
    Other commenters objected to EPA's proposal to adopt a definition, 
citing on-going litigation in Electric Energy, Inc., et al. v. EPA, 
Case Nos. 22-1056 and 23-1035. These commenters complained that EPA 
makes no mention of this litigation in the proposed rule, even as it 
claims that its interpretation is ``sufficiently clear that a 
definition is not necessary.'' One commenter further stated that if EPA 
ultimately elects to adopt regulatory definitions of those terms, it 
should wait until the court rules so that the definitions are informed 
by and consistent with any such ruling.
    Another commenter asserted that EPA must acknowledge (and make a 
good faith attempt to reconcile) the competing interpretations of key 
terms of art in the 2015 CCR Rule before extending them into this final 
rule.
    One commenter argued that even if EPA adopted its proposed 
definition, the rule provides no criteria--in contrast to the detailed 
criteria for the necessary cover system--for how to ``control, minimize 
or eliminate to the maximum extent feasible'' horizontal groundwater 
``infiltration.'' The commenter alleged that ``this type of undefined 
performance standard would be void for vagueness, especially when 
compared to the great lengths EPA went to specify the other technical 
criteria to address vertical infiltration in the performance 
standard.''
    EPA also received numerous comments recommending that infiltration 
be defined by reference to technical definitions that define 
infiltration as exclusively the vertical flow of water from the surface 
down into the unit. These included a definition provided by the U.S. 
Geological Survey (``USGS''), as ``flow of water from the land surface 
into the subsurface.'' Also, according to the USGS: ``Water that 
infiltrates at land surface moves vertically downward to the water 
table to become ground water. The ground water then moves both 
vertically and laterally within the ground-water system.''
    As discussed previously, EPA disagrees that it is necessary to wait 
until the court issues its decision in the pending litigation (Electric 
Energy, Inc., et al. v. EPA, Case Nos. 22-1056 and 23-1035). However, 
the court may rule on the procedural question at issue, it would not 
resolve the substantive question EPA posed in the proposal, of whether 
the inclusion of a definition would be useful.
    EPA also disagrees that it should adopt a definition of 
infiltration as exclusively the vertical flow of water from the surface 
down into the unit. The purpose of adopting a definition is not to 
establish a generic definition of infiltration, but to assist in the 
application of standards to ensure that a CCR unit closes in a manner 
that will protect human health and the environment. When promulgating 
definitions applicable in regulatory programs, EPA relies not only on 
available dictionary definitions, but also the surrounding context of 
the regulation as a whole, as well as what will best achieve the 
overall purpose of the regulation, and the Agency's statutory mandate. 
None of the commenters address-any of these factors in recommending 
that EPA adopt their various technical definitions. In this case, the 
plain language definition of infiltration best fits within the context 
of the regulation as a whole, and best achieves both the purpose of the 
regulation and the RCRA section 4004(a) mandate to protect human health 
and the environment. This is because under the commenters' 
unnecessarily restrictive definitions the regulation would allow a 
significant number of sites to continue leaking hazardous constituents, 
such as arsenic and mercury, indefinitely.
    Accordingly, the final rule adopts a definition of infiltration 
based on the dictionary definitions discussed in the proposal. The 
final rule defines infiltration to mean ``the migration or movement of 
liquid, such as surface water or ground water, into or through a CCR 
unit from any direction, including from the surface, laterally, and 
through the bottom of the unit.'' This definition also is consistent 
with two technical sources that use infiltration more broadly by 
incorporating lateral flow through continuous porous media. As EPRI 
explained in its comments, Geotechnical Aspects of Landfill Design and 
Construction (Qian 2002) does not contain an explicit definition of 
infiltration but does refer to both ``surface water infiltration'' and 
``groundwater infiltration'' in its description of landfill leachate. 
Similarly, the National Research Council in Assessment of the 
Performance of Engineered Waste Containment Barriers (National Research 
Council 2007) does not explicitly define infiltration but uses 
infiltration to describe surface water and groundwater movements into 
waste as well as soil migration into drainage systems.
    With respect to the comment requesting EPA to ``acknowledge (and 
make a good faith attempt to reconcile) the competing interpretations 
of key terms of art in the 2015 regulation,'' EPA considers that its 
adoption of this definition does this. As noted, the definition is 
consistent with both the plain language meaning of the term, and with 
relevant technical sources. Further, the definition fits within the 
context of the regulation as a whole and best achieves both the purpose 
of the regulation and RCRA's mandate to protect human health and the 
environment.
    Finally, EPA disagrees that the regulation, with or without a 
regulatory definition of infiltration, is unconstitutionally vague. The 
scope of the regulatory definition is clear, and thus regulated parties 
have adequate notice of the rule's requirements.
    In point of fact, the commenter's complaint is not that it cannot

[[Page 39078]]

determine what is required under the regulation, but that it dislikes 
what the plain language clearly compels. Relying on the plain language 
definition of infiltration simply requires facilities that want to 
close an unlined CCR impoundment with waste in place to implement 
engineering measures to ``control, minimize, or eliminate, to the 
maximum extent feasible'' liquid entering the unit from the sides or 
the base of the unit. EPA has previously identified several reasonably 
available engineering measures exist that can prevent, or at least 
control, the flow of groundwater into the unit (and consequently the 
releases out of the unit). For example, EPA's 1982 guidance on the 
closure of hazardous waste surface impoundments, which the commenter 
also references, identifies several engineering controls ``to prevent 
the subsurface flow of ground water into the impounded waste.'' EPA 
Office of Solid Waste, Closure of Hazardous Waste Surface Impoundments, 
SW-873, p 81 (September 1982), Revised Edition (emphasis added). In 
other words, the regulation ``clearly proscribes'' the commenter's 
preferred conduct of closing its CCR impoundments without addressing 
the groundwater in its unit. Finally, Sec.  257.102(d)(1)(i) is no more 
vague than the corresponding requirement in Sec.  265.111(a), which has 
been in effect since 1982 (requiring interim status facilities to 
``control, minimize or eliminate to the extent necessary to protect 
human health and the environment, post-closure releases of leachate . . 
.). The clarity of this regulation is shown by the fact that, over the 
past 40 years the regulation has been in effect, interim status 
hazardous waste facilities have been able to adequately determine what 
the regulation requires and comply with it. The commenter has offered 
nothing to distinguish the interim status requirements from those in 
Sec.  257.102(d)(i).
(3) Closure in Place Performance Standards Under Sec.  257.102(d)
    The May 2023 proposal explained how the performance standards for 
closing with waste in place applied to a CCR surface impoundment that 
intersected with groundwater. EPA received a number of comments that 
agreed with the Agency's explanation, as well as several that opposed 
it. Several commenters raised objections they had previously presented 
in the context of prior decisions. EPA has previously responded to 
these comments in detail in (1) U.S. EPA. Denial of Alternative Closure 
Deadline for General James M. Gavin Plant, Cheshire, Ohio (November 18, 
2022) in the docket at EPA-HQ-OLEM-2021-0590-0100; (2) 88 FR 31982 (May 
18, 2023); and (3) 88 FR 55220 (August 14, 2023). EPA continues to be 
unpersuaded by the commenters objections and to avoid any confusion is 
reiterating below the explanation provided in the May 2023 proposal.
    The CCR closure requirements applicable to closing with waste in 
place include general performance standards and specific technical 
standards that set forth individual engineering requirements related to 
the drainage and stabilization of the waste and to the final cover 
system. The general performance standards and the technical standards 
complement each other, and both must be met at every unit.
    The specific technical standards related to the drainage of the 
waste in the unit require that, ``free liquids must be eliminated by 
removing liquid wastes or solidifying the remaining wastes and waste 
residues.'' 40 CFR 257.102(d)(2)(i). Free liquids are defined as all 
``liquids that readily separate from the solid portion of a waste under 
ambient temperature and pressure,'' regardless of whether the source of 
the liquids is from sluiced water or groundwater. 40 CFR 257.53. 
Consequently, the directive applies to both the freestanding liquid in 
the impoundment and to all readily separable porewater in the 
impoundment, whether the porewater was derived from sluiced water, 
stormwater run-off, or groundwater that migrates into the impoundment. 
In situations where the waste in the unit is inundated with 
groundwater, the requirement to eliminate free liquids thus obligates 
the facility to take engineering measures necessary to ensure that the 
groundwater, along with the other free liquids, has been permanently 
removed from the unit prior to installing the final cover system. See, 
40 CFR 257.102(d)(2)(i).
    In addition to the process-specific technical requirements, all 
closures must meet the requirements in the general performance standard 
to ``control, minimize or eliminate, to the maximum extent feasible,'' 
both post closure infiltration of liquids into the waste and releases 
of CCR or leachate out of the unit to the ground or surface waters, and 
to ``preclude the probability of future impoundment of water, sediment, 
or slurry.'' 40 CFR 257.102(d)(1)(i), (ii).
    In situations where the groundwater intersects an unlined CCR unit, 
water may infiltrate into the unit from the sides and/or bottom of the 
unit because the base of the unit is below the water table. In this 
scenario, the CCR in the unit will be in continuous contact with water. 
This contact between the waste and groundwater provides a potential for 
waste constituents to be dissolved and to migrate out of (or away from) 
the closed unit. In such a case, the general performance standard also 
requires the facility to take measures, such as engineering controls, 
that will ``control, minimize, or eliminate, to the maximum extent 
feasible, post-closure infiltration of liquids into the waste'' as well 
as ``post-closure releases to the groundwater'' from the sides and 
bottom of the unit. 40 CFR 257.102(d)(1).
    Whether any particular unit can meet these performance standards is 
a fact and site-specific determination that will depend on a number of 
considerations, such as the hydrogeology of the site, the design and 
construction of the unit, and the kinds of engineering measures 
implemented at the unit. Accordingly, the fact that prior to closure 
the base of a unit intersects with groundwater does not mean that the 
unit may not ultimately be able to meet the performance standards in 
Sec.  257.102(d) for closure with waste in place.
    Depending on the site conditions, a facility may be able to meet 
these performance standards by demonstrating that a combination of 
engineering measures and site-specific circumstances will ensure that 
as a consequence of complying with the closure performance standards, 
the groundwater will no longer be in contact with the waste in the 
closed unit. As one example, where groundwater intersects with only a 
portion of an impoundment, the facility could close that portion of the 
unit by removing the CCR from that area of the unit but leaving waste 
in place in other areas. As another example, if the entire unit sits 
several feet deep within the water table, engineering controls can 
potentially be implemented to stop the continued flow of groundwater 
into and out of the waste. See, EPA Office of Solid Waste, Closure of 
Hazardous Waste Surface Impoundments, SW-873, p 81 (September 1982), 
Revised Edition.
(4) Methods and Tools for the Identification and Elimination of Free 
Liquids
    Many commenters requested EPA provide greater clarity regarding the 
closure performance standard that requires that ``free liquids must be 
eliminated by removing liquid wastes or solidifying the remaining 
wastes and waste residues.'' 40 CFR 257.102(d)(2)(i). Commenters stated 
that there continues to be confusion over

[[Page 39079]]

what technical means and methods can be implemented to meet EPA's 
expectations and, in particular, what design considerations must be 
taken into account to achieve compliance with the existing closure 
performance standards (as applied to both currently and newly regulated 
units). The commenters explained that there are no regulatory 
specifications for eliminating free liquids prior to installing the 
final cover system or controlling, minimizing or eliminating, to the 
maximum extent feasible, the post-closure infiltration of liquids as 
required by Sec.  257.102(d)(2)(i) and (d)(1)(i), respectively.
    In response to these requests, EPA is providing further information 
with this final rule. EPA has included in the docket to this rulemaking 
a document titled ``Methods and Tools for the Identification and 
Elimination of Free Liquids.'' A summary of some of the main points of 
the guidance are discussed below.
    The document discusses many of the methods and tools needed to 
identify and eliminate free liquids that are already widely used by 
industry to investigate and close surface impoundments. For example, 
tools that may be used to identify free liquids include soil borings 
and cone penetrometers to map the stratigraphy of the CCR unit and 
characterize the geotechnical and hydraulic properties of the various 
CCR layers, as well as the installation of traditional piezometers, 
monitoring wells and vibrating wire piezometers to monitor pore 
pressures and water levels. Properly constructed wells and piezometers 
screened in the appropriate locations and depths have a prominent role 
in networks of instruments necessary for assessing free liquids in that 
their design directly measures water levels under ambient conditions. 
At the most basic level water levels in wells and piezometers are 
indicative of free liquids. Conversely, networks of wells and 
piezometers could be used as part of a program used to determine that 
free liquids no longer exist. Similarly, methods and tools to eliminate 
free liquids within the CCR, such as rim ditches, pumping wells, 
extraction wellpoints are also currently employed by industry. These 
technologies also provide insights into the presence and nature of free 
liquids at a given CCR unit, e.g., rim ditches and open excavations 
enable direct observation of free liquids.
    Finally, the document identifies considerations useful to 
developing successful site-specific strategies and approaches to 
identify, measure, monitor and eliminate free liquids. Longer term 
variables such as potential groundwater intrusion or other influences 
are also discussed. In summary, full compliance requires successful 
sustained attainment of performance standards over the long term. 
Designing successful approaches will necessarily involve careful 
consideration of all potential sources of free liquids, including 
groundwater. Owners or operators of units that contain CCR in contact 
with groundwater will likely need to take additional actions such as 
CCR removal or implement specific engineering measures applied over 
time frames needed to preclude groundwater from intruding back into CCR 
units after free liquids have been initially eliminated.
iv. Preparation of a Written Closure Plan for CCR Management Units
    EPA proposed that owners or operators of CCRMU comply with the 
existing requirements of Sec.  257.102(b) requiring the preparation of 
a written closure plan no later than 12 months after the effective date 
of the final rule.
    As mentioned in Unit III.C.4.d, aside from those commenters that 
disagreed with requiring CCRMU to comply with overall closure 
requirements, commenters on the proposed rule agreed that the written 
closure plan requirement would generally be appropriate for CCRMU. One 
commenter suggested additional requirements for the content of the 
closure plan including the elevation of the base of the unit, 
groundwater information, and descriptions of compliance with Sec.  
257.102 will be achieved (e.g., how free liquids would be eliminated, 
how waste will be stabilized, measures to minimize the need for further 
maintenance of the CCR unit). A few commenters supported the proposed 
deadline but as summarized in Units III.C.4.a and III.C.4.d of this 
preamble, other commenters stated the proposed deadline was infeasible 
and inappropriate. One commenter suggested the deadline for the closure 
plan be extended to be concurrent with the initiation of closure. 
Another commenter requested EPA create extension mechanisms for this 
requirement based on the number of CCRMU at the facility. Commenters 
suggestions for the deadline for the completion of the closure plan 
ranged from 12 (the 2015 CCR Rule deadline) to 60 months.
    EPA disagrees with the commenter that additional requirements 
regarding the content of the closure plan are necessary. The 
information the commenter requested be included in the closure plan is 
1) already required to be in the closure plan pursuant to Sec. Sec.  
257.102(b) or 2) readily available in other required reports (e.g., the 
annual groundwater monitoring and corrective action reports). 
Furthermore, the commenter failed to fully explain how compliance with 
Sec.  257.102(b) does not provide the information needed to determine 
if compliance with the closure performance standards will be met.
    Regarding the deadline, for the same reasons in Units III.B.2.g and 
III.B.2.g.iv.b for legacy CCR surface impoundments, EPA concludes that 
the deadline for the closure plan should be extended from the proposed 
deadline to allow for owners or operators to incorporate information 
about groundwater quality, groundwater flows, seasonality impacts, and 
the migration of contaminants (if any) into the plan. Therefore, EPA is 
finalizing a deadline of no later than Wednesday, November 8, 2028, 
which is 48 months after the effective date. This final deadline 
extends the proposed deadline by 36 months and EPA expects that this 
adequately address the concern regarding the infeasibility of the 
deadline expressed by a commenter requesting EPA create extension based 
on the number of CCRMU at the facility. This is codified in the 
regulatory text at Sec.  257.102(b)(2)(iii).
    However, consistent with the requirements for legacy CCR surface 
impoundments, EPA is not requiring compliance with the written closure 
plan requirement for CCRMU that, by the effective date of this final 
rule, have completed: (1) closure with waste in place or (2) a closure 
eligible for deferral to permitting as described in Sec.  257.101(g). 
Instead, the final rule requires the owner or operator to provide 
information on the completed closure of the CCRMU, along with 
supporting documentation to demonstrate that the closure meets the 
performance standards in Sec.  257.102(d) or the standards specified in 
Sec.  257.101(g). This is codified in the regulatory text at Sec.  
257.102(b)(2)(v).
    Based on comments on the proposed rule and experience from the 2015 
CCR Rule, EPA expects the incorporation of this information into the 
closure plan will allow facilities to select a closure method that most 
appropriately addresses issues like waste that is in contact with 
groundwater, groundwater contamination, and long-term structural 
stability concerns. Closure plans that adequately address these issues 
will result in better protection of human health and the environment.
    The closure plan describes the steps necessary to close a CCR unit 
at any

[[Page 39080]]

point during the active life of the unit based on recognized and 
generally accepted good engineering practices. 40 CFR 257.102(b)(1). 
The plan must set out whether the closure of the CCR unit will be 
accomplished by leaving CCR in place or through closure by removal and 
include a written narrative describing how the unit will be closed in 
accordance with the section, or in other words, how the closure will 
meet all the performance standards in the regulations. 40 CFR 
257.102(b)(1)(i). The written closure plan must also provide a schedule 
for completing all activities necessary to satisfy the closure criteria 
of the rule. See also 80 FR 21410-21425.
    If the CCR is left in place, the closure plan must include a 
description of the final cover system and how the final cover system 
will achieve the regulatory performance standards. If the base of the 
impoundment intersects with groundwater, the closure plan would need to 
discuss the engineering measures taken to ensure that the groundwater 
had been removed from the unit prior to the start of installing the 
final cover system, as required by Sec.  257.102(d)(2)(i). The closure 
plan would also need to describe how the facility plans to meet the 
requirements in Sec.  257.102(d)(1) to ``control, minimize or 
eliminate, to the maximum extent feasible, post-closure infiltration of 
liquids into the waste and releases of CCR, leachate, or contaminated 
run-off to the ground or surface waters.'' This could include, for 
example, the installation of engineering controls that would address 
the post-closure infiltration of liquids into the waste from all 
directions, as well as any post-closure releases to the groundwater 
from the sides and bottom of the unit.
v. Preparation of a Written Post-Closure Care Plan for CCR Management 
Units
    EPA proposed that owners or operators of CCRMU would be required to 
comply with the existing requirement in Sec.  257.104(d) regarding the 
preparation of a written post-closure no later than 12 months after the 
effective date of the final rule.
    As mentioned in Unit III.C.4.d, aside from those commenters that 
disagreed with requiring CCRMU to comply with overall closure 
requirements, commenters on the proposed rule agreed that the written 
post-closure care plan requirement would generally be appropriate for 
CCRMU. Overall commenters requested an extension of the post-closure 
care deadline to allow for a more feasible deadline and the 
incorporation of groundwater monitoring data. Another commenter 
requested EPA create extension mechanisms for this requirement based on 
the number of CCRMU at the facility. For the same reasons in Units 
III.B.2.g and III.B.2.g.iv.c for legacy CCR surface impoundments, EPA 
is finalizing a deadline of no later than Wednesday, November 8, 2028, 
which is 48 months from the effective date of the final rule to comply 
with the post-closure care requirement in Sec.  257.104(d). This final 
deadline extends the proposed deadline by 36 months and EPA expects 
that this adequately address the concern regarding the infeasibility of 
the deadline expressed by commenter requesting EPA create extension 
based on the number of CCRMU at the facility. This is codified in the 
regulatory text at Sec.  257.104(d)(2)(iii).
    Section 257.104(d) requires that an owner or operator of a CCR unit 
prepare a written post-closure plan. The contents of the P.E.-certified 
plan are stated in the rule Sec.  257.104(d)(1)(i) through (iii) and 
can be summarized as a description of the monitoring and maintenance 
activities required for the unit, the frequency that these activities 
will be performed, information for the point-of-contact during the 
post-closure care period, and planned uses of the property.
vi. Deadline To Initiate Closure for CCR Management Units
    EPA proposed that owners or operators of CCRMU initiate closure no 
later than 12 months after the effective date of the final rule. As 
explained in the proposed rule, the proposed deadline was expedited 
from the 2015 CCR Rule to address the risks posed from these units and 
EPA's estimated minimum amount of time necessary to collect the 
information needed to determine whether to close the unit in place or 
close by removal.
    Several commenters expressed support for the proposed 12-month 
deadline to initiate closure, stating that the shorter deadlines are 
necessary to address the increased risk from CCRMU and likelihood these 
units are and have been contaminating groundwater. However, as 
mentioned in Unit III.C.4.d, many other commenters characterized the 
proposed deadline as infeasible for the reasons mentioned in Unit 
III.C.4.a, including seasonality, need to comply with overlapping 
regulatory requirements, labor shortages, and the strain on the limited 
resources necessary to achieve compliance (e.g., contractors, 
laboratories, P.E.s) caused by the number of CCR units coming into 
compliance at the same time. Commenters emphasized the importance of 
the groundwater monitoring data to inform closure, stating that 
compliance with the closure requirements should not be required until 
after the groundwater monitoring system was installed and baseline 
samples collected. These commenters pointed to recent EPA Part A and 
Part B decisions as evidence of the gap between EPA's expectations and 
the closure and post-closure plans developed by owners or operators and 
best practices; these commenters further stated that the proposed 
deadline precludes the incorporation of groundwater monitoring data in 
developing closure plans and is likely a contributing factor to the gap 
between EPA's expectation and closure and post-closure care plans 
submitted by owners or operators of currently regulated units. 
Additionally, as described in Unit III.C.4.d.ii, several commenters 
requested the delays for the initiation of closure for CCRMU beneath 
critical infrastructure until the decommissioning or closure of the 
infrastructure or facility. Finally, a few commenters suggested EPA 
create extensions for the deadline to initiate closure to address 
concerns about comply with overlapping State permitting requirements or 
based on the number of CCRMU present at the facility. Commenters' 
suggestions for alternative deadlines to initiate closure ranged from 
12 with extensions to 60 months, or at least after the collection of 
the baseline groundwater monitoring samples required by Sec.  257.94.
    Consistent with the approach for legacy CCR surface impoundments 
closure, EPA acknowledges the benefit of allowing owners or operators 
the time needed to incorporate groundwater monitoring data into the 
closure plan. Additionally, as stated in the proposed rule, EPA 
acknowledges the importance of using information gained by compliance 
with the groundwater monitoring and corrective action requirements to 
inform closure decisions and therefore the initiation of closure. For 
the reasons explained in Unit III.C.4.c, EPA is extending the deadline 
for the groundwater monitoring and corrective action requirements to a 
single deadline of no later than 42 months from the effective date of 
the final rule. As such, the initiation of closure is being extended as 
well. To ensure owners or operators have enough groundwater monitoring 
data to draw conclusions about seasonality impacts on groundwater 
levels and flow and the source of any potential groundwater 
contamination in the area, EPA is finalizing a deadline of no later 
than Tuesday, May 8, 2029, which is 54 months from the effective

[[Page 39081]]

date of the final rule. This is codified in the regulatory text at 
Sec.  257.101(f)(1). This final deadline extends the proposed deadline 
by 42 months and EPA expects that the concerns expressed by commenters 
requesting EPA create extensions (i.e., the need to comply with State 
permitting requirements and the number of CCRMU at the facility) are 
addressed by this overall deadline extension. Finally, regarding those 
CCRMU under critical infrastructure, owners or operators of these units 
have the opportunity to defer the deadline to initiate closure until 
the Agency can address these units on an individual basis as part of 
permitting. See Unit III.C.4.d.ii.
vii. Deadline To Complete Closure for CCR Management Units
    EPA proposed to apply the current CCR surface impoundment closure 
time frames at Sec.  257.102(f) to CCRMU. The existing CCR regulations 
currently require an owner or operator of a CCR surface impoundment 
generally to complete closure activities within five years from 
initiating closure. The regulations also establish the conditions for 
extending this deadline, upon a showing that additional time is 
necessary. Consistent with the existing requirements for CCR surface 
impoundments, EPA proposed the amount of additional time that an owner 
or operator could obtain would vary based on the size (using surface 
area acreage of the CCR unit as the surrogate of size) of the CCRMU. 
For CCRMU 40 acres or smaller, the proposed maximum time extension is 
two years. For CCRMU greater than 40 acres, the proposed maximum time 
extension is five 2-year extensions (10 years), and the owner or 
operator must substantiate the factual circumstances demonstrating the 
need for each year extension.
    Several commenters expressed support for the proposed deadlines to 
complete closure, citing the increased risk from CCRMU and likelihood 
these units are and have been contaminating groundwater. However, many 
commenters on the proposed rule requested an extension of the deadline 
to complete closure to allow for a more feasible deadline and to 
mitigate the factors mentioned in Unit III.C.4.a. Some of these 
commenters stated if the deadline to initiate closure was extended to 
no less than the time granted for CCR unit closure in the 2015 CCR 
Rule, then the proposed deadlines would be feasible. These commenters 
supported the ability of CCRMU to seek extensions of the deadline based 
on size. However, a few of the commenters requested longer extensions 
or an increase in the maximum number of extensions for CCRMU. These 
commenters cited factors mentioned in Unit III.C.4.a as reasons to 
allow for longer or more extensions (i.e., third-party availability, 
need to comply with State permitting requirements prior to certain 
activities, backlogs, number of CCR units coming into compliance at the 
same time). One commenter stated more extensions were necessary to meet 
the closure performance standards in Sec.  257.102 (i.e., remove liquid 
from the unit and meet the groundwater protection standards).
    For the reasons described throughout this Unit of the preamble, EPA 
has extended the deadline for the initiation of closure. EPA expects 
the extension to the deadlines for the closure plan and initiation of 
closure, as well as the options to defer closure requirements for CCRMU 
under critical infrastructure and those that have completed closure 
under a regulatory authority (see Units III.C.4.d.ii and 
III.C.4.d.iii.a, respectively), to address the concerns commenters 
expressed with the infeasibility or inappropriateness of the deadline 
to complete closure. Furthermore, with respect to requests for longer 
or more extensions for CCRMU as compared to the existing CCR 
regulations, EPA still concludes that as explained in the proposed 
rule, CCRMU closure will closely resemble CCR impoundment closures 
because of half of these identified potential CCRMU were associated 
with former, Federally unregulated CCR surface impoundments. 
Additionally, the requirements for former impoundments to be closed 
with waste in place (i.e., procurement, transportation, and placement 
of substantial volumes of soil or borrow material), would also apply to 
certain CCR fill placements as well as to inactive CCR landfills where 
past waste disposal did not reach the landfill's design capacity (i.e., 
landfill airspace was not fully utilized). As such, in these 
situations, EPA has determined the time frames to complete closure for 
existing CCR surface impoundments are appropriate (i.e., 5 years). 
Finally, as discussed in proposed rule, the Agency believes that the 
base of at least some CCRMU may intersect with the groundwater because 
CCRMU may be located in floodplains or wetlands, or near large surface 
water bodies. EPA's experience in implementing the regulations is that 
such closures are generally more complex and take longer to complete. 
EPA thus believes the time frames to complete closure of CCRMU should 
be the same as the time frames provided for existing CCR surface 
impoundments. No commenters provided factual information or evidence to 
support the conclusion that CCRMU closure, apart from those CCRMU under 
critical infrastructure or closed under a regulatory authority 
mentioned above, is different enough from closure of units regulated 
under the 2015 CCR Rule to warrant additional extensions or separate 
requirements. Therefore, EPA is finalizing the deadline for the 
completion of closure of CCRMU as proposed. This is codified in the 
regulatory text at Sec.  257.102(f).
viii. Post-Closure Care for CCR Management Units
    EPA proposed to apply the existing post-closure care requirements 
at Sec.  257.104 to CCRMU without revision. These criteria are 
essential to ensuring the long-term safety of CCRMU.
    As mentioned in Unit III.C.4.d, aside from those commenters that 
disagreed with requiring CCRMU to comply with overall closure 
requirements, no commenters raised specific concern about requiring 
CCRMU to comply with the existing requirements in Sec.  257.104. 
However, one commenter suggested that EPA allow units that have closed 
under a State program to either continue post-closure care under that 
State program or reduce the post-closure care period for these units by 
the number of years of post-closure care completed under the State 
program. As described in Unit III.C.4.d.iii(a), EPA is finalizing a 
provision to address closures completed under other authorities 
provided the closure meets specific criteria by deferring any closure 
activities to permitting, including the determination of when post-
closure care is completed. In instances where the criteria for deferral 
to permitting has been met and units have conducted post-closure care 
under a State program for many years, the permitting authority, once 
authorized, will be able to look at the site-specific information, 
including the closure and the specific activities required by the 
State's post-closure care program, and determine what, if any, further 
closure or post-closure activities would be appropriate. EPA is 
therefore finalizing this provision without revision.
    The existing post-closure care criteria require the monitoring and 
maintenance of units that have closed in place for at least 30 years 
after closure has been completed. 40 CFR 257.104. During this post-
closure period, the facility would be required to continue groundwater 
monitoring and corrective action, where necessary.

[[Page 39082]]

e. Recordkeeping, Notification and Internet Posting for CCR Management 
Units

    EPA proposed that, like legacy CCR surface impoundments, owners or 
operators of CCRMU be subject to the existing recordkeeping, 
notification and website reporting requirements in the CCR regulations 
found at Sec. Sec.  257.105 through 257.107. EPA also proposed changes 
to add CCRMU to Sec.  257.107(a) to require the facility to notify the 
Agency using the procedures for the establishment of the website no 
later than the effective date of the final rule. For reasons specified 
in the 2015 CCR Rule, the CCR regulations require the owner or operator 
of a new or existing CCR unit to record specific information in the 
facility's operating record, maintain files of all required information 
(e.g., demonstrations, plans, notifications, and reports) that supports 
implementation and compliance with the rule, notify State Director and 
Tribal authorities, and maintain a public CCR website that hosts this 
information. 80 FR 21427.
    A commenter supported applying recordkeeping, notification, and 
internet posting requirements to CCRMU but stated that the existing 
requirements were ineffective at ensuring compliance with the CCR 
regulations or allowing for meaningful public awareness or 
participation. The commenter suggested that EPA create mechanisms 
within the rule to ensure the public has the opportunity to participate 
in the decision-making processes at regulated CCR units; standardize 
reporting to make the report more easily understood by the public; 
establish organizational requirements for the CCR websites; require 
public notice and engagement when notifying the State Director and/or 
appropriate Tribal authority as required by the CCR rule; extend the 
period of time the files required by the CCR rule must be maintained in 
the operating record; and require owners or operators certify 
compliance documentation for the CCR units. This commenter also 
suggested EPA clarify what records owners or operators are required to 
retain and to publish. Other commenters suggested the website 
requirement not be due until the first document is required to be 
posted.
    EPA agrees with the commenter on the importance of meaningful 
public participation. The current regulations allow for public 
participation by requiring owner or operators to hold a public meeting 
as part of the assessment of corrective measures in Sec.  257.96, 
creating a mechanism for the public to file dust complaints in Sec.  
257.80(b), and the ``contact us'' form or specific email address on 
facilities' public CCR websites for questions or issues from the public 
as required by Sec.  257.107(a). Public comment periods are also held 
as part of the determination process for Part A and Part B 
demonstrations; however, these demonstrations are not applicable to 
CCRMU. EPA does not have evidence to support the claim by the commenter 
that these opportunities for public participation are ineffective. 
Furthermore, EPA does not find other decision-making points in the rule 
appropriate for mandatory public meetings or public comment periods 
although facilities are encouraged to engage with the public and to 
both solicit and incorporate public input into decisions, such as 
closure methods, as able and appropriate.
    With respect to the commenter's suggestions that EPA require the 
owners or operators of CCR units to certify compliance documentation 
and create standardized reporting and website layout requirements, as 
explained in the proposed rule, EPA does not have evidence that CCRMU 
are sufficiently different than currently regulated facilities to 
necessitate substantially different requirements. The commenter 
provided no factual basis to support the suggestion that requiring 
owner or operator certifications would improve compliance with the 
regulations beyond the certifications currently required by 
professional engineers. When justifying the request for standardized 
reporting and website layout requirements, the commenter failed to 
explain how compliance with the public website posting requirements in 
Sec.  257.107, including the requirement to ensure all information is 
``clearly identifiable and must be able to be immediately printed and 
downloaded by anyone accessing the site'' is inadequate or a hinderance 
to the public accessing the required information. Therefore, EPA does 
not believe additional notification, certification, or public 
engagement requirements for CCRMU would be appropriate.
    EPA agrees with the commenter on the need to extend the period of 
time files required by the CCR rule must be maintained on the 
facilities' public websites and in the operating records. As described 
in Unit III.D.5, EPA is extending how long files must be maintained in 
the operating record and on the public website. While EPA believes the 
regulations at Sec. Sec.  257.105 and 257.107 clearly lay out what 
records must be retained and published, EPA has included in Unit 
III.D.5. a table that details what records are required to be 
maintained in the operating record and on the public website as well as 
the corresponding retention periods. No commenters raised concerns 
about requiring CCRMU to comply with the existing requirements in 
Sec. Sec.  257.105 through 257.107.
    Lastly, EPA agrees with the commenters who suggested the deadline 
for the establishment of the website coincide with the first required 
document (i.e., the FER Part 1). Therefore, EPA is finalizing a 
deadline of 15 months after the effective date for the establishment of 
the website.
    EPA is also finalizing the requirement that owners or operators of 
CCRMU comply with recordkeeping, notification, and internet posting 
requirements at Sec. Sec.  257.105 through 257.107.
    As discussed in Unit III.B.2.h of this preamble, owners or 
operators must document implementation and compliance with the rule and 
must place these files into the facility's operating record. Each 
required file must be maintained in the operating record for the 
entirety of the retention period specified in Sec.  257.105 following 
submittal of the file into the operating record. Each file must also 
indicate the date the file was placed in the operating record. Files 
are required to be submitted into the operating record at the time the 
documentation becomes available or by the compliance deadline specified 
in the CCR regulations. Section 257.105 contains a comprehensive 
listing of each recordkeeping requirement and corresponding record 
retention periods.
    Furthermore, the owner or operator of a CCRMU must maintain a CCR 
website titled, ``CCR Rule Compliance Data and Information'' that hosts 
the compliance information so that it may be viewed by the public. 
Unless provided otherwise in the rule (see, Unit III.E.5), information 
posted to the CCR website must be available for a period no less than 
five years from the initial posting date for each submission. Posting 
of information must be completed no later than 30 days from the 
submittal of the information to the operating record. Owners or 
operators of CCRMU have 15 months from the effective date of this rule 
to establish a CCR website and post the required applicable 
information.

D. Closure of CCR Units By Removal of CCR

1. Background
    On March 3, 2020, in the Proposed Rule entitled: Hazardous and 
Solid Waste Management System: Disposal of CCR; A Holistic Approach to 
Closure Part B: Alternate Demonstration for

[[Page 39083]]

Unlined Surface Impoundments; Implementation of Closure, EPA proposed 
to revise the 2015 CCR Rule to, among other things, provide facilities 
with an additional option for CCR units being closed by removal of CCR. 
85 FR 12456. Specifically, EPA proposed to allow a facility to complete 
the closure in two stages: first, by completing all removal and 
decontamination procedures; and second, by completing all groundwater 
remediation in a separate post-closure care period. 85 FR 12456. In 
this final rule, the Agency is taking final action on this proposal.
    The closure by removal regulation consists of two performance 
standards. In the first standard, the owner or operator must remove all 
CCR from the unit and decontaminate all areas affected by releases from 
the CCR unit. In the second standard, the regulation specifies that 
closure is complete when all CCR in the unit and any areas affected by 
releases from the CCR unit have been removed and groundwater monitoring 
demonstrates that there are no exceedances of any groundwater 
protection standard. See Sec.  257.102(c). Importantly, the second 
performance standard requires groundwater corrective action of a unit 
to be completed in order for closure of the unit to be considered 
complete.
    As previously discussed, the CCR regulations also establish 
deadlines to initiate and complete closure activities. For example, the 
regulations generally require owners and operators of CCR surface 
impoundments to complete closure activities within five years of 
commencing closure activities, while closure of CCR landfills must be 
completed within six months. See Sec.  257.102(f)(1). Notwithstanding 
these deadlines to complete closure, the CCR regulations also allow for 
additional time provided the owner or operator can make the prescribed 
demonstrations that are based on site-specific circumstances beyond the 
facility's control. For CCR surface impoundments, the amount of 
additional time beyond the five years varies based on the demonstrated 
need and the surface area acreage of the impoundment. For impoundments 
40 acres or smaller, the maximum time extension that can be obtained is 
two years. For impoundments greater than 40 acres, the maximum time 
extension is five two-year extensions (for a total extension of ten 
years). For CCR landfills, the amount of additional time beyond the six 
months does not vary according to the size of the landfill, rather the 
maximum time extension is two one-year extensions (for a total 
extension of two years). To obtain additional time, owners or operators 
of CCR units must substantiate the factual circumstances demonstrating 
the need for the extension. See Sec.  257.102(f)(2). In all instances 
the number of time extensions is capped to a certain number of years.
    The CCR regulations also require the owner or operator of the CCR 
unit to obtain a certification from a qualified professional engineer 
or approval from the Participating State Director (or EPA where EPA is 
the permitting authority) verifying that closure has been completed in 
accordance with the written closure plan and all applicable closure 
requirements of Sec.  257.102. See Sec.  257.102(f)(3). In addition, 
the owner or operator must prepare a notification stating that closure 
of the unit has been completed. This notification must be completed 
within 30 days of completion of unit closure and must include the 
certification required by Sec.  257.102(f)(3). See Sec.  257.102(h). As 
the CCR regulations are currently structured for units closing by 
removal of CCR, the closure certification and notification cannot be 
completed until all CCR removal and decontamination activities, 
including groundwater corrective action,\146\ are completed. Prior to 
this final rule, owners and operators that complete closure of a unit 
by removal of CCR were exempt from any other post-closure care 
requirements for the unit and were also exempt from the deed notation 
requirements upon certification that closure by removal of CCR has been 
completed.
---------------------------------------------------------------------------

    \146\ For purposes of this preamble discussion, the term 
``groundwater corrective action: includes those actions taken to 
implement the selected remedy specified in Sec.  257.98(c) to attain 
the groundwater protection standards in Sec.  257.95(h).
---------------------------------------------------------------------------

2. March 2020 Proposed Rule
    Under the March 2020 proposal, an owner or operator that cannot 
complete groundwater corrective action by the time all other closure by 
removal activities have been completed (i.e., during the active life 
\147\ of the CCR unit) may complete groundwater corrective action 
during a post-closure care period. Under this option, the owner or 
operator must first complete all other removal and decontamination 
activities within the time frames provided for completing closure. In 
addition, EPA proposed to require the owner or operator to have 
implemented the remedy selected under Sec.  257.97 such that all 
components of the remedy are in place and operating as intended prior 
to completing all removal and decontamination activities. Upon 
completion of all removal and decontamination activities (except for 
completion of groundwater corrective action) and implementation of the 
selected remedy, the owner or operator would be allowed to certify that 
the CCR unit has been closed. Thereafter, the CCR unit would be 
required to continue to conduct corrective action in accordance with 
the existing requirements in Sec.  257.98 and would be subject to the 
existing post-closure care requirements in Sec.  257.104 until 
completion of groundwater corrective action. EPA did not propose any 
substantive revisions to the current closure standard when closing by 
removal of CCR under Sec.  257.102(c), but presented the current 
closure standard in a slightly revised format to accommodate the 
proposed action.
---------------------------------------------------------------------------

    \147\ The ``active life'' of a CCR unit is defined in Sec.  
257.53 as the period of operation beginning with the initial 
placement of CCR in the CCR unit and ending at completion of closure 
activities in accordance with Sec.  257.102.
---------------------------------------------------------------------------

    EPA proposed this option because the Agency received new 
information indicating that the closure of CCR units will likely be 
more complex than EPA envisioned in 2015, and that more than 40% of 
existing CCR surface impoundments were planned to be closed by removal 
of CCR. In addition, available information indicated that more than 70% 
of all CCR surface impoundments are unlined. EPA determined that, given 
the number of unlined CCR units, many of which have already reported 
exceedances of groundwater protection standards, it was evident that 
many CCR units have released CCR constituents into the surrounding 
soils and groundwater. EPA concluded that this meant that closure would 
not simply be a matter of removing CCR from the unit, but would likely 
require a significant undertaking to remediate impacted soil and 
groundwater in order to achieve the current CCR removal and 
decontamination standards. The proposal explained that based on this 
new information EPA concluded that the existing timelines to complete 
closure by removal of CCR were not designed to also provide sufficient 
time to complete groundwater corrective action. The Agency explained 
that it was also concerned that the existing deadlines in Sec.  
257.102(c) may create a disincentive to close a unit by removal of CCR.
    After considering the comments received, the same considerations 
discussed in the proposal remain relevant. Moreover, the groundwater 
monitoring installed pursuant to the 2015 CCR Rule has documented 
groundwater contamination that is more extensive and more frequent that 
EPA had originally estimated. It is now apparent not only that a 
greater number

[[Page 39084]]

of facilities are electing to close by removal than EPA originally 
estimated, but also that some facilities may need to close by removal 
because they are unable to meet the standards to close with waste in 
place due to the site conditions. And more critically, EPA is concerned 
that, based on the existing time frames, some facilities could not 
comply with either performance standard because it is not feasible to 
remediate the contamination within the existing deadlines in Sec.  
257.102(f). EPA has therefore incorporated this provision into this 
final rule.
    Most of the comments EPA received on this proposal \148\ related to 
the revised regulatory text in Sec.  257.102, the requirement to 
implement the corrective action remedy during the active life of the 
unit and the requirement for deed notifications. One commenter also 
stated that there was nothing in the record to demonstrate that 
facilities were not able to meet the existing Sec.  257.102(c) 
performance standard by deadlines in Sec.  257.102(f). The commenter 
also expressed concern that the proposed option would allow exceedances 
of groundwater protection standards to continue indefinitely after an 
impoundment is closed by removal. Further, the commenter contended that 
the proposed change did not include any additional requirements for 
owners and operators to substantiate the need to take additional time 
following removal activities. This, they stated, could incentivize the 
selection of the slowest, least protective corrective measures such as 
``natural attenuation,'' allowing dangerous contamination to persist 
for long periods of time when it could have been stopped decades 
earlier. They were concerned that owners or operators would 
unreasonably select remedies that take much longer to achieve 
compliance over other available options that could achieve compliance 
faster.
---------------------------------------------------------------------------

    \148\ See the Response to Comments document found in the docket 
for this rule.
---------------------------------------------------------------------------

    The Agency disagrees that there is no record to support the need 
for additional time to complete groundwater remediation within the time 
frames provided in Sec.  257.102(f). For example, this same commenter 
submitted comments on the May 2023 proposed rule providing examples of 
numerous plants who have certified the removal portion of closure by 
removal while noting the need for additional time beyond the existing 
deadlines in Sec.  257.102(f) in order to be able to certify compliance 
with GWPS.\149\ These facilities include Duke Energy's Gibson Station, 
LG&E-KU's Ghent Generating Station, and Dominion Energy's Possum Point 
Power Station.
---------------------------------------------------------------------------

    \149\ EPA-HQ-OLEM-2020-0107-0368.
---------------------------------------------------------------------------

    Additionally, EPA compiled data on remediation efforts published in 
the Superfund 5-Year Review Reports conducted pursuant to CERCLA Sec.  
121(c).\150\ The data review focused on sites that presented releases 
of metals similar to those expected at CCR facilities and sites that 
were likely to choose remediation technologies that could also be 
applicable to CCR facilities. The compilation included data for 20 
sites with groundwater remediation remedies in place for at least 15 
years. There were eight sites that implemented a combination of 
remediation strategies (for example, pump and treat and vertical 
barrier wall in the same site). The most common remedy noted was pump 
and treat (14 sites), followed by monitored natural attenuation (MNA) 
(eight sites), barrier walls (five sites), in-situ stabilization (two 
sites), and permeable reactive barriers (one site). At the time of this 
data compilation, 18 out of 20 remedies were still ongoing with cleanup 
durations ranging from 15 to more than 32 years. 11 of 20 remedies 
exceeded 20 years of operation.
---------------------------------------------------------------------------

    \150\ Memorandum from RTI International to Mary Jackson, U.S. 
EPA, Development of Benchmark Times for Conducting the Closure of 
CCR Units, February 29. 2024. Superfund 5-Year Review Reports 
conducted pursuant to CERCLA Sec.  121(c). Available in the docket.
---------------------------------------------------------------------------

    The Agency also disagrees that the proposal would allow exceedances 
to continue indefinitely, and the owner or operator to purposely choose 
the slowest, least protective groundwater remediation technology. The 
facility would remain subject to the existing requirements for 
corrective action, Sec. Sec.  257.96 through 257.98, which prohibit the 
actions the commenter describes. Additionally, the facility must have 
initiated remedial activities as required by Sec.  257.98(a) during the 
active life of the unit in order to be eligible for this closure 
alternative. The sole exception to this would be where the facility 
only triggered corrective action for the constituent near the end of 
the closure process, and the facility cannot extend the active life of 
the unit because it would exceed a deadline in Sec.  257.102(f). In 
such a case, the facility would be required to document that (1) it was 
in compliance with all applicable requirements in Sec. Sec.  257.96 
through 257.98; and (2) that it could not extend the active life of the 
unit, consistent with Sec.  257.102(f).
3. What EPA Is Finalizing Related to the March 2020 Proposed Rule
    EPA is finalizing its proposal with some limited revisions adopted 
in response to public comments. Under this final rule and consistent 
with the proposal an owner or operator would be able to able to close a 
CCR unit by completing removal of all CCR from the unit and 
decontamination of all areas affected by releases from the CCR unit, 
except for groundwater, during the active life of the CCR unit, and 
completing the groundwater corrective action during post-closure care. 
The owner or operator will need to meet the following requirements when 
closing a CCR unit under this option. First, the owner or operator must 
complete all removal and decontamination activities, except groundwater 
corrective action, during the active life of the unit. Second, with one 
exception, the owner or operator must have begun to implement the 
corrective action remedy selected in accordance with Sec. Sec.  257.96 
through 257.97 to achieve compliance with the GWPS during the active 
life of the unit (i.e., before completing closure). Third, groundwater 
corrective action must be completed during post-closure care. Fourth, 
the owner or operator must amend the written closure and post-closure 
plans to reflect this approach to close the unit. Fifth, the owner or 
operator must obtain the certification or approval of closure 
completion within the current time frames for closure in Sec.  
257.102(f). Finally, prior to the start of the post-closure care 
period, the owner or operator must record the notation on the deed to 
the property that the land has been used as a CCR unit. Each of these 
requirements is discussed further below. EPA is revising the regulatory 
text of Sec.  257.102(c) and Sec.  257.104(g) and (h). The revisions to 
Sec.  257.104 are to make it clear that the unit must be in detection 
monitoring in order to complete post closure care.
a. Removal and Decontamination Activities
    EPA proposed to revise the closure performance standard at Sec.  
257.102(c) to specify all of the various actions that would be required 
prior to certifying that closure is complete. EPA proposed that this 
would include removing or decontaminating all CCR and CCR residues, 
containment system components, contaminated subsoils, contaminated 
groundwater, and CCR unit structures and ancillary equipment. To 
qualify for the new closure by CCR removal option, owners or operators 
would need to complete all the specified removal and decontamination

[[Page 39085]]

activities within the closure time frame except for completing 
groundwater remediation. The proposal specified that to demonstrate 
that all CCR has been removed from the unit, the owner or operator 
would need to remove the entire contents of the CCR unit, including all 
CCR and any CCR residues. This would include, for example, the removal 
of any fugitive dust (CCR) discovered outside the waste unit boundary. 
In addition, the proposal specified that any containment system 
components such as a bottom liner, contaminated subsoils, and unit 
structures and equipment (e.g., concrete outlet structures and 
ancillary piping) would have to be removed prior to closure of the 
unit. Finally, EPA proposed that any areas affected by releases from 
the CCR unit must have been removed (e.g., impacted soils beneath the 
bottom liner system).
    Commenters pointed out that the term ``CCR residues'' was not a 
defined term. They also pointed out that it may not be necessary or 
wise to require the removal of ancillary equipment or structures if 
they are not contaminated with CCR. Further, they pointed out that 
requiring the removal of fugitive dust outside the unit boundary would 
expand the closure performance standard.
    One commenter was concerned that the term ``CCR unit structures,'' 
appears to encompass both areas impacted by CCR disposal (which should 
be removed) and non-contaminated disposal unit structural components, 
which, according to the commenter, in some cases includes CCR that has 
been beneficially used in the construction of the impoundment or other 
disposal units (which the commenter asserted need not be removed). The 
commenter further stated that structural components, including those 
structures built with beneficially reused CCR (e.g., bottom ash), must 
be allowed to remain in place.
    The Agency does not agree that components of the unit that are 
constructed with CCR can be left in place if the unit is in fact 
closing by removal of CCR. If the unit is to be ``closed by removal of 
CCR,'' consistent with the existing requirement to remove all CCR, the 
final rule requires that any components of the unit made of or 
including CCR must also be removed.
    The regulatory text included in this final rule requires removing 
all CCR from the unit, including CCR mixed with soils or that are 
included in berms, liners or other unit structures, and either removing 
or decontaminating all areas affected by releases from the CCR unit. 
Although there are no soil cleanup standards in the CCR regulations, if 
the soil beneath the unit is contaminated sufficiently to serve as a 
secondary source of groundwater contamination, its removal may be 
required as part of the source control portion of a remedy selected 
under Sec.  257.97. To clarify, contaminated groundwater (groundwater 
with constituent concentrations triggering corrective action) must be 
remediated through the corrective action process detailed in Sec. Sec.  
257.96 through 257.98.
    Although the regulatory text now specifies the removal and 
decontamination activities to be conducted, the Agency does not 
consider this to be a substantive revision to Sec.  257.102(c). The 
revision is intended to clearly describe the activities that must be 
completed prior to closure under the new alternative in Sec.  
257.102(c)(2). The regulation now expressly describes how EPA 
interpreted the original phrase ``CCR removal and decontamination.'' 
Therefore, the regulatory text for Sec.  257.102(c) has been revised 
from what was proposed:

    (c) Closure by removal of CCR. An owner or operator closing a 
CCR unit by removal of CCR must follow the procedures specified in 
either paragraph (c)(1) or (c)(2) of this section. Closure by 
removal activities include removing or decontaminating all CCR and 
CCR residues, containment system components such as the unit liner, 
contaminated subsoils, contaminated groundwater, and CCR unit 
structures and ancillary equipment.

To what is being finalized:

    (c) Closure by removal of CCR. An owner or operator that elects 
to close a CCR unit by removal of CCR must follow the procedures 
specified in either paragraph (c)(1) or (c)(2) of this section. 
Closure by removal is complete when CCR has been removed; any areas 
affected by releases from the CCR unit have been removed or 
decontaminated; and groundwater monitoring concentrations of the 
constituents listed in appendix IV to this part do not exceed 
groundwater protection standards established pursuant to Sec.  
257.95(h). Removal and decontamination activities include removing 
all CCR from the unit, CCR mixed with soils, and CCR included in 
berms, liners or other unit structures, and removing or 
decontaminating all areas affected by releases from the CCR unit.

    Under this provision, the owner or operator must complete all CCR 
removal activities during closure prior to transitioning to the post-
closure care period which will largely consist of a groundwater cleanup 
activity.
b. Implementation of Selected Remedy
    Under the existing regulations, if one or more constituents in 
Appendix IV to part 257 are detected at SSLs above the GWPS in any 
sampling event, the owner or operator must, among other requirements, 
initiate a corrective action program. See Sec.  257.95(g). The 
corrective action program includes initiating an assessment of 
corrective measures to prevent further releases, to remediate any 
releases, and to restore affected areas to original conditions, as 
specified in Sec.  257.96(a). After the ACM has been completed, the 
owner or operator must select a remedy that meets prescribed standards, 
including a requirement that the remedy attain the GWPS. See Sec.  
257.97(a) and (b). Finally, the corrective action program requires the 
owner or operator of the CCR unit to initiate remedial activities 
within 90 days of selecting a remedy. See Sec.  257.98(a). EPA did not 
propose to revise any of these requirements as part of this option. 
However, under this closure option, the owner or operator must have 
initiated remedial activities required by Sec.  257.98(a) prior to 
certifying that it has completed closure. This requirement would help 
ensure that impacted groundwater is returned to original conditions as 
soon as is feasible.
    Several commenters objected to this requirement. Some of these 
commenters suggested that at many sites, it is not appropriate to 
implement a remedy before source removal is complete. Other commenters 
claimed that after excavation is complete at certain sites, new 
groundwater flow patterns may be established and/or groundwater 
chemistry may need to stabilize, and in these cases neither design nor 
implementation of a corrective measure may be practical before CCR 
removal is finished. A few commenters went further yet, stating that it 
would not be appropriate to require completion of an ACM and selection 
of a remedy until after CCR removal activities are complete. Finally, 
other commenters state that source control is required by Sec.  
257.97(b) and may be considered part of the remedy, therefore, 
implementation of the remedy would commence with closure by removal.
    Under the existing regulations, the closure requirements and the 
corrective action requirements operate independent of one another, and 
facilities are required to comply with both. The commenters cite 
nothing to support their claim that closure must be completed prior to 
initiating corrective action. In fact, it would be inconsistent with 
the existing mandatory deadlines for initiating and pursuing corrective 
action. For example, Sec.  257.96(a) requires an ACM to be initiated 
within 90 days of determining an SSL has occurred, and then completed 
within another 90

[[Page 39086]]

days. An extension, not to exceed 60 days, may be warranted due to 
site-specific conditions or circumstances. EPA did not propose to 
revise these deadlines, so comments suggesting changes to these 
provisions are outside the scope of the rulemaking. Additionally, the 
commenters provided no reason why corrective measures could not be 
assessed and compared in an ACM and a remedy could not be selected. 
Long before initiating closure of a CCR unit, the facility was required 
to characterize site conditions, including groundwater flow conditions 
and geology to design and install the groundwater monitoring system. 
See, e.g., Sec.  257.91(b). The facility already has knowledge of the 
wastestreams and water volumes it disposes into a CCR surface 
impoundment. This information can be used to develop a groundwater 
model to predict groundwater flow conditions after wastestream disposal 
ceases and closure is initiated, which would provide sufficient 
characterization of post-closure conditions to assess and compare 
groundwater cleanup alternatives to complete an ACM. The commenters 
have provided neither reasons nor explanation why this would not be 
feasible.
    Once the ACM is complete, a public meeting has been held, and 
community input has been considered, a remedy must be selected as soon 
as feasible. EPA agrees that a selected remedy may include closure by 
removal to comply with source control requirements, and that this would 
constitute commencing implementation of a remedy. However, the selected 
groundwater remediation portion of the remedy must also be implemented 
within a reasonable time, in accordance with the schedule established 
in the remedy selection report. 40 CFR 257.97(d). Implementation of the 
source control measure does not satisfy this separate requirement.
    With respect to commenters' assertion that the design and 
implementation of the groundwater remediation portion of the remedy is 
not feasible until closure by removal is complete, the commenters 
provided no explanation or reasons to support this claim, although one 
commenter identified MNA as an example of such a remedy. EPA does not 
agree that design or implementation of MNA would need to be delayed due 
to closure activities. The ACM would include identification of 
attenuation mechanisms and characterization of site conditions 
influencing them. This could be based on current site conditions and 
any modeled future conditions. If MNA is evaluated more favorably than 
other groundwater remedies and is ultimately selected, it requires no 
construction other than installation of additional monitoring wells to 
identify plume boundaries and monitor performance. This installation 
would occur downgradient of the unit and should not be affected by unit 
closure activities. The data from downgradient wells are critical to 
determining if MNA is working. While groundwater elevations may 
decrease after dewatering a surface impoundment, and therefore 
additional wells may need to be installed with screens at lower 
elevations later in the corrective action process, this would be an 
expected aspect of implementing MNA for a CCR unit.
    Some commenters mentioned that geochemical conditions of 
groundwater may change during closure. The commenters did not provide 
specific reasons for this or the anticipated effects of excavation. 
While removal of CCR is not expected to remove reactants available for 
immobilization reactions (i.e., any attenuation mechanisms) from the 
environment, EPA agrees that groundwater chemistry could be impacted, 
particularly near the excavation site. However, in the absence of 
evidence that permanent immobilization mechanisms are viable at the 
site, either under current conditions or in modeled future conditions, 
MNA would not meet the Sec.  257.97(b) criteria for selection as a 
remedy.
    The CCR regulations establish independent performance standards for 
corrective action and closure. The regulations do not provide for 
delaying corrective action while closure occurs, or vice versa. In the 
example of MNA or, in fact, any groundwater remedy, delaying remedy 
implementation until after closure is complete would be inconsistent 
with the requirement in Sec.  257.98(d) to complete remedial activities 
within a reasonable period. This is particularly true in this example, 
because collecting monitoring data is the primary action required in an 
MNA remedy. When data collection is delayed, those data are lost. 
Because this monitoring can be done during closure, it is required in 
order to move forward with corrective action as soon as possible.
    Additionally, delaying groundwater remediation would not be 
protective. When a release has been detected, corrective action to 
clean up the contamination is necessary to prevent it from migrating to 
downgradient receptors, both human and environmental. Because Appendix 
IV constituents persist in the environment, delaying corrective action 
increases the amount of the contamination that is released to the 
environment and allows existing contamination to move further 
downgradient. To ensure there will be no reasonable probability of 
adverse effect on health or the environment as EPA is required to do 
under RCRA section 4004(a), the final regulation requires that 
corrective action be implemented in accordance with the requirements of 
Sec. Sec.  257.96 through 257.98 without unnecessary or unreasonable 
delays.
    Further, as one commenter mentioned, in the event that measures 
taken to implement the remedy following closure are not proving to be 
effective, the remedy can be altered during corrective action. Under 
the existing regulations, an owner or operator is required to 
``implement other methods or techniques that could feasibly achieve 
compliance'' if, after the remedy is implemented, it is determined that 
compliance is not being achieved. 40 CFR 257.98(b). If such additional 
measures are necessary after certification of closure, an owner/
operator would have the ability to undertake those measures without 
impacting the facility's closure certification.
    Therefore, EPA is finalizing the proposal that the owner or 
operator must have initiated the remedial activities as required by 
Sec.  257.98(a) in order to be eligible for this closure alternative.
    The sole exception would be if the facility only triggered 
corrective action for a constituent sufficiently late in the closure 
process that it would not be feasible to delay closure until a remedy 
could be selected. For example, if a facility first detected an SSL of 
antimony one week before the deadline to complete closure in Sec.  
257.102(f), it would not be possible to comply with all of the 
requirements in Sec. Sec.  257.96-257.97 before the deadline. As 
explained above, the closure and corrective action obligations are 
independent of one another and run concurrently. To prevent placing a 
facility in such a position, EPA has incorporated a provision to allow 
the facility to demonstrate that it was not feasible to implement the 
corrective action remedy prior to the expiration of a deadline in Sec.  
257.102(f). In such a case, the facility must document that (1) it was 
in compliance with all applicable requirements in Sec. Sec.  257.96 
through 257.98; and (2) that it could not extend the active life of the 
unit, consistent with Sec.  257.102(f).

[[Page 39087]]

c. Groundwater Corrective Action
    For owners and operators that close a unit under this provision, 
the CCR unit would remain subject to the post-closure care requirements 
under Sec.  257.104 until groundwater corrective action has been 
completed. These units would not be subject to the requirement to 
conduct post-closure care for 30 years; rather, these units would 
remain in post-closure care until all groundwater monitoring and 
corrective action requirements are completed, which may be longer or 
shorter than 30 years. EPA proposed that groundwater corrective action 
is complete when the groundwater monitoring concentrations do not 
exceed the groundwater protection standards for constituents listed in 
Appendix IV to part 257. EPA has reconsidered this, as the Agency did 
not intend to modify the existing requirement for completing post-
closure care, which also applies to concluding post closure care for a 
unit closed with waste-in-place. The existing provision in Sec.  
257.104(c) states that post-closure care ends after 30 years unless at 
the end of the post-closure care period the owner or operator of the 
CCR unit is operating under assessment monitoring in accordance with 
Sec.  257.95. If the unit remains in assessment monitoring, the owner 
or operator must continue to conduct post-closure care until the owner 
or operator returns to detection monitoring in accordance with Sec.  
257.95. This means that there can be no detections of any Appendix IV 
constituents for two consecutive sampling events. Therefore, the final 
regulatory text has been revised to account for this.
    The requirement to be in detection monitoring to conclude the post-
closure care is the same standard currently specified in the 
requirements for closure by leaving waste in place. This rule does not 
change any requirements of the groundwater monitoring and corrective 
action program. The owner or operator would need to conduct groundwater 
monitoring and corrective action in accordance with the requirements of 
Sec. Sec.  257.90 through 257.98. See revised Sec.  257.104(c).
d. Closure and Post-Closure Care Plans
    The Agency is finalizing as proposed the requirement that owners 
and operators closing a CCR unit under this new closure alternative 
would need to revise their written closure plan. The closure plan 
describes the closure of the unit and provides a schedule for 
implementation of the plan. The owner or operator would need to revise 
the current plan and describe how the CCR unit would be closed in 
accordance with the revised closure options. The current CCR 
regulations already include procedures to amend written plans under 
certain circumstances, including when there is a change in the 
operation of a CCR unit that would substantially affect the current 
written plan or when unanticipated events necessitate a revision of the 
plan. See Sec.  257.102(b)(3)(ii). EPA expects owners and operators to 
revise the current closure plan according to these existing procedures. 
This rule also requires owners or operators opting for this approach to 
prepare an initial post-closure care plan within six months of the 
effective date of this final rule. The post-closure care plan describes 
how the CCR unit will be maintained after closure of the unit is 
completed. Prior to this final rule, CCR units that closed by removal 
of CCR are exempt from any post-closure care requirements so the 
preparation of a post-closure care plan will be a new requirement for 
owners and operators closing a unit under this new option. EPA believes 
that six months from the effective date of this final rule, or one year 
from publication of this final rule is a reasonable amount of time to 
prepare the post-closure care plan because the owner or operator should 
already have prepared the closure plan for the unit and begun 
implementation of the corrective measures remedy.
    EPA is aware that some facilities that planned to close a unit by 
removal of CCR nonetheless completed a post-closure care plan. In this 
situation, the CCR regulations already include requirements to amend 
written plans under certain circumstances, including when there is a 
change in the operation of a CCR unit that would substantially affect 
the current written plan or when unanticipated events necessitate a 
revision of the plan. See Sec.  257.104(d)(3). EPA expects that these 
owners or operators would revise the existing post-closure care plan 
according to these existing procedures.
e. Notation on the Deed to the Property
    Under the existing regulations, following the closure of a CCR unit 
that will be subject to post-closure care, the owner or operator must 
record a notation on the deed to the property, or some other instrument 
that is normally examined during title search, notifying any potential 
purchaser of the property in perpetuity that the land has been used as 
a CCR unit, and its use is restricted under the post-closure care 
requirements. See Sec.  257.102(i). The rationale for this requirement 
is to ensure that prospective and subsequent owners are aware of the 
presence of a closed unit on the property and of the need for continued 
maintenance of the cover or of any ongoing corrective actions. 
Following that same logic, units that have closed by removal in 
accordance with Sec.  257.102(c) have been exempt from the deed 
notation requirement, both because all waste and associated 
contamination have been removed, and because there is no continuing 
post-closure care that needs to be maintained.
    Units closing under this new closure option will be required to 
record a deed notation because they would not have closed by removal in 
accordance with Sec.  257.102(c)(1) (as corrective action would not 
have been completed) and because post-closure care would be required. 
See Sec.  257.102(i)(4). But these units are not wholly analogous to 
the other units subject to a deed notation (i.e., those closing with 
waste in place). Units falling under this new closure option will have 
already had all waste removed in its entirety and so would require no 
continued maintenance. However, groundwater remediation actions would 
be continuing, raising concern about potential exposures.
    Therefore, EPA proposed that the owner or operator record a 
notation on the deed to the property (or some other instrument normally 
examined during a title search) until all groundwater corrective action 
has been completed--that is, when groundwater monitoring concentrations 
do not exceed the groundwater protection standard established pursuant 
to Sec.  257.95(h) for constituents listed in appendix IV to part 257. 
EPA proposed the deed notation because all removal and decontamination 
actions have not been completed. Given that groundwater corrective 
action may continue for years or decades, the deed restrictions are a 
practical way of limiting human exposure during a period when 
contamination is still present, and thereby ensuring that the statutory 
standard under RCRA section 4004(a) continues to be met.
    As part of the post-closure care provisions under Sec.  257.104, 
EPA proposed to allow removal of the deed notation, or the addition of 
a second notation reflecting the inapplicability of the first notation, 
as may be applicable under existing State or local law, when 
groundwater corrective action is completed for the CCR unit. Under this 
closure option, completion of groundwater corrective action would 
indicate that all removal and decontamination actions have been 
completed. To remove the deed notation (or add a second notation), the 
owner or

[[Page 39088]]

operator would need to complete two actions. First, the owner or 
operator would need to demonstrate that groundwater monitoring 
concentrations no longer exceed any groundwater protection standard 
established pursuant to Sec.  257.95(h) for constituents listed in 
Appendix IV to part 257. See Sec.  257.104(g). Second, the owner or 
operator would need to complete the notification stating the post-
closure care requirements have been met as required in Sec.  
257.104(e). Removing the deed notation upon completion of all removal 
and decontamination activities is consistent with the current 
procedures for CCR units that close by removal under Sec.  
257.102(i)(4).
    The existing CCR regulations require a specific type of control 
(i.e., deed notations) to communicate use limitations to present and 
future users of the land with the closed CCR unit. The Agency solicited 
comments on whether the use of deed restriction controls is too narrow 
under this new closure option and whether the CCR regulations should 
allow for the use of different legal mechanisms and controls to 
communicate limits on the activities that can safely take place at the 
site. Some commenters supported inclusion of more flexibility and 
alternative instruments to accomplish this purpose. For example, one 
commenter pointed out that in Colorado, the State routinely uses 
Environmental Use Restrictions/Environmental Covenants. Other 
commenters asserted that EPA should allow the owner or operator to 
determine which instrument to use or allow the Participating State 
Director to decide. ASTSWMO commented that the proposed language 
requiring the use of deed restriction controls appears to be consistent 
with language in 40 CFR 258.60(i) as applicable to Municipal Solid 
Waste (MSW) Landfills, and that it might be helpful for States that the 
language between CCR and MSW landfills aligns.
    Other commenters mentioned the importance of deed notations is that 
it compels impoundment owners to create a publicly accessible record 
attached to a property deed noting that the property is subject to 
ongoing groundwater corrective action requirements. Attaching such a 
note to the deed also ensures any subsequent owner of the property 
would be on notice of ongoing cleanup obligations and would be liable 
for following through on them. The commenter stated that any 
alternative to deed notification that EPA may be considering (i.e., 
other approaches under private property law) should only be considered 
if they also provide these benefits of the deed notification 
requirement.
    The Agency has decided to finalize the proposal to require that the 
owner or operator record a notation on the deed to the property until 
all groundwater corrective action has been completed. EPA agrees that a 
deed notation performs an important function to ensure any subsequent 
owner of the property is on notice of the ongoing cleanup obligations 
and of the liability of any subsequent owner until those obligations 
are completed. None of the commenters provided sufficient information 
for EPA to conclude that the alternative measures that they suggested 
would provide the same level of assurance as a deed notation. Moreover, 
the use of a deed notation is consistent with the requirements for MSW 
landfills and with CCR units closing by leaving waste in place, and 
therefore EPA expects the public and regulated entities will be 
familiar with them. Additionally, as discussed above, once the closure 
by removal is complete, the owner or operator can remove the deed 
notification.
f. Closure Certification or Approval
    The Agency is adopting without revision the proposal that the owner 
or operator will continue to be subject to the same certification or 
approval requirement that is currently applicable to all CCR units as 
specified in Sec.  257.102(f)(3). Under this requirement, the owner or 
operator must obtain a certification from a qualified P.E. or approval 
from the Participating State Director (or EPA where EPA is the 
permitting authority) verifying that closure has been completed in 
accordance with the written closure plan and all applicable closure 
requirements of Sec.  257.102. Under this provision, the certification 
or approval would reflect that all removal and decontamination 
activities, except for groundwater corrective action, have been 
completed. The certification or approval would not address the 
remediation of the impacted groundwater because groundwater corrective 
action will be completed during the post-closure care period, including 
applicable post-closure care certification and approval requirements.

E. Technical Corrections

    Through the implementation of the 2015 CCR Rule, the Agency 
identified several minor errors and inconsistencies. Therefore, EPA is 
amending the CCR regulations to clarify definitions, accurately 
reference the definition of wetlands, and use consistent language when 
referring to publicly accessible internet sites. The Agency is also 
amending an incorrect reference to Sec.  257.99 in the groundwater 
monitoring scope section. Finally, EPA is extending the period for 
certain document retention and posting.
1. Definitions of ``Technically Feasible'' and ``Technically 
Infeasible''
    EPA proposed to revise the definition of technically feasible to 
clarify that the terms technically feasible and feasible have the same 
meaning in the regulations. The existing regulations define technically 
feasible as ``possible to do in a way that would likely be 
successful.'' EPA codified this definition in 2020 when amending the 
alternative closure requirements for landfills and impoundments. 85 FR 
53542 (August 28, 2020). As EPA explained, the definition was based on 
two dictionary definitions of ``feasible'': ``capable of being done or 
carried out'' (Merriam website (https://www.merriam-webster.com/dictionary/feasible)) and ``possible to do and likely to be 
successful'' (Cambridge English Dictionary (https://dictionary.cambridge.org/us/dictionary/english/feasible)). Id.
    However, some rule provisions use the term feasible. EPA never 
intended to distinguish between these terms. See, e.g., 80 FR 21422-
21423, 85 FR 53542. Therefore, EPA proposed to add the term feasible to 
the existing definition of technically feasible to make clear that both 
terms have the same meaning in the regulations. This definition 
revision would be accomplished by adding ``or feasible'' to the 
existing definition so that the definition would read ``Technically 
feasible or feasible means possible to do in a way that would likely be 
successful.'' For similar reasons, EPA proposed to also revise the 
definition of technically infeasible to clarify that the terms 
technically infeasible and infeasible have the same meaning in the 
regulations.
    EPA received comments on this issue that opposed adding 
``feasible'' and ``infeasible'' as definitions. The commenters said the 
term ``feasible'' is used in the Sec.  257.102(f)(2)(i) standard for 
obtaining extensions to the closure time frames, and that if EPA 
finalizes the provision as proposed, the change should not be applied 
retroactively to facilities that used the closure extension. Other 
commenters said this is not how EPA should correct regulatory errors 
and there is a lack of discussion on all situations and regulatory 
history regarding these terms.
    EPA disagrees that these terms have different meanings under the 
CCR regulations or that this clarification will

[[Page 39089]]

negatively impact implementation of the requirements by regulated 
entities. See, 85 FR 53542 (relying on dictionary definitions of 
``feasible'' to define `technically feasible'). EPA is simply 
clarifying the meaning of these synonymous terms. Id. Therefore, EPA is 
finalizing these changes as proposed. This is codified in the 
regulatory text at Sec.  257.53.
2. Wetlands Reference Correction
    When the 2015 CCR Rule was finalized in April 2015, Sec.  257.61(a) 
referenced Sec.  232.2, which contained a definition of wetlands. An 
EPA and United States Army Corps of Engineers joint final rule 
published June 29, 2015 (80 FR 37053) amended Sec.  232.2 by removing 
the definition of wetlands. However, the reference to Sec.  232.2 in 
Sec.  257.61(a) of the 2015 CCR Rule was not updated. EPA proposed an 
amendment that would correct the CFR reference for the wetlands 
definition by referring to 40 CFR 230.41(a) (December 24, 1980, 45 FR 
85344). EPA received one comment on this issue about the U.S. Supreme 
Court decision in Sackett v. EPA, 21-454, in which the Court 
substantially narrowed the scope of wetlands subject to Federal 
jurisdiction under the Clean Water Act. EPA reviewed the Sackett 
decision and determined that the wetlands definition contained in Sec.  
257.61(a) remains valid after that decision. EPA is therefore 
finalizing this provision as proposed. This is codified in the 
regulatory text at Sec.  257.61.
3. Groundwater Monitoring and Corrective Action Applicability
    EPA proposed to correct a typographical error in the initial 
applicability paragraph of the groundwater monitoring and corrective 
action regulations. In Sec.  257.90(a), the existing regulations refer 
to the ``groundwater monitoring and corrective action requirements 
under Sec. Sec.  257.90 through 257.99''; however, there are no 
requirements codified under Sec.  257.99. This was brought to EPA's 
attention by a State interested in permit program approval. To avoid 
confusion with the regulations, EPA proposed to revise the section 
references in Sec.  257.90(a) to read ``groundwater monitoring and 
corrective action requirements under Sec. Sec.  257.90 through 
257.98.'' EPA did not receive any comments on this issue and is 
therefore finalizing this provision as proposed.
4. Publicly Accessible Internet Site
    EPA proposed to change several provisions using the term ``CCR 
website'' to ``CCR website,'' which is the term used in Sec.  
257.107(a). The inconsistent spelling of CCR website was brought to our 
attention by a State interested in permit program approval. To avoid 
confusion with the regulations, EPA proposed to correct such references 
in Sec. Sec.  257.100(e)(1)(iii) and 257.107(b) through (j). EPA did 
not receive any comments on this issue and is therefore finalizing 
these provisions as proposed.
    EPA is also revising Sec.  257.107(b) to provide owners and 
operators the flexibility to maintain one website for multiple electric 
power sector rules. This new provision allows an owner or operator to 
document the facility's compliance with the requirements of other 
environmental rules on the same website that is used for CCR units. In 
order to use a combined website, the final rule requires that the owner 
or operator delineate the postings for each regulatory program under a 
separate heading on the website. For example, the required CCR rule 
postings must be placed under a ``CCR Rule Compliance Data and 
Information'' heading, while postings required by the ELG rule would be 
posted under a separate heading ``ELG Rule Compliance Data and 
Information.'' \151\ EPA is providing this flexibility to reduce 
paperwork burden and make it easier for communities to access this 
information.
---------------------------------------------------------------------------

    \151\ See Sec.  423.19 for ELG rule posting requirements.
---------------------------------------------------------------------------

5. Document Retention
    The CCR regulations require the production of many documents that 
provide information on many aspects of regulated CCR units, for example 
from history of construction to periodic inspections, as well as 
closure activity and groundwater sampling and cleanup, if necessary. 
These documents must be retained in the facility operating record as 
well as posted on the facility CCR website, generally for a five-year 
period. In the proposed rule, EPA requested comment on potential 
revision of document posting and retention times currently in the 
regulations. EPA raised the concern that some of the current retention 
times may be too short to accomplish the goals underlying the posting 
requirement, namely transparency and information availability. This 
concern stems from the fact that information that is still relevant for 
CCR units may reach the original retention time limit while the 
availability of the documents would still serve the purposes of 
transparency and information availability after the original retention 
deadline.
    The comments received were largely in favor of revising the 
document retention periods, though those commenters who provided 
suggested approaches or examples of longer retention periods were not 
entirely consistent in the approaches offered.
    One commenter opposed the concept of expanding the retention time 
for any documents that are required to be posted on facility websites. 
This commenter stated the current retention period provides clear 
guidance to the regulated community and that extending the retention 
period could add to additional redundant or outdated material on the 
websites. This commenter also said that the purpose of the website 
posting requirement has been obviated by the passage of the WIIN Act. 
For several reasons, EPA disagrees with this comment. First, the 
regulations already include provisions to decrease or eliminate 
redundancy or outdated postings. See, for example, Sec.  257.107(g)(1), 
which requires only the most recent dust suppression plan to be 
maintained on the website. Second, the core principle of the website 
posting requirement is relevance: facilities are required to post 
information relevant to the operation and closure of CCR units and 
cleanup of any releases from those units. It is clear that a five-year 
retention period may not be adequate for documents that remain relevant 
well beyond that length of time, which is proving to be true for many 
of the required documents. Third, while it is true that website posting 
is one of several measures EPA implemented in the original rule before 
the WIIN Act was enacted, nothing in the WIIN Act makes the goals of 
transparency and information availability for communities and other 
interested parties obsolete.
    The other commenters all agree that extensions to the website 
posting and retention time periods are warranted. Those comments that 
included actual time frame suggestions based those suggestions on the 
type of document and relevance to the operation, closure, and cleanup 
requirements of the regulations, though they varied in the exact 
approach and length of extensions.
    EPA has decided that to accomplish the regulatory goals underlying 
the document preparation and retention requirements, longer retention 
times are required. Therefore, EPA is revising the retention periods as 
provided in this final rule. EPA does agree that the approach for 
extensions should be based on the nature of each document and the 
relevance of each document to demonstrating compliance with regulatory 
milestones. This approach was already employed in the 2015 CCR

[[Page 39090]]

Rule for numerous documents (e.g., the groundwater remedy selection 
document is currently required to be retained until remedy completion). 
See Sec.  257.107(h)(9). In this rule, EPA is applying this same 
approach to other documents prepared under the regulations.
    There are several related issues that are involved in the document 
preparation, retention and posting requirements that deserve discussion 
here. First, the website posting regulations in Sec.  257.107 are 
companions to, and cross-reference, the operating record regulations in 
subpart Sec.  257.105. The interrelation of these sections means that 
this revisiting of the website posting regulations necessitates a 
review of those regulations that address the placing and retaining of 
documents in the facility operating record. Accordingly, EPA is 
including accompanying retention time period changes to Sec.  257.105 
as appropriate and relevant to the changes to Sec.  257.107. 
Additionally, as suggested by several commenters, the retention of the 
documents in the operating record for a longer period than retention on 
the website not only makes sense for some documents, but supports the 
Agency not requiring that every prepared document remain on the 
website. This is particularly true for documents that are either 
periodically updated or result from recurring assessments. In 
implementing this approach, the Agency is mindful of and in agreement 
with the comments that urged the Agency to not require the posting of 
all documents out of concern that the websites would become cluttered 
and confusing.
    Second, a related issue arises where there may be more than one 
version of a document, which version of a required document must be 
posted or retained in the operating record. This situation arises, for 
example, when a required document is updated or a document is required 
to be prepared for recurring assessments. Where appropriate, the 
regulations are being revised to ensure they are clear about what 
version or versions of documents must be posted and retained.
    A third issue is that, for some documents, the five-year retention 
and posting duration requirements may have expired. However, some of 
these documents are still relevant to an operating or closing unit, or 
a unit in post-closure care status or undergoing groundwater cleanup. 
For these documents, the purposes of retaining and posting them are 
still viable and there are compelling reasons to ensure these documents 
are available on the facility website and in the facility operating 
record. EPA is, therefore, requiring that documents that may have been 
taken down and removed from operating records are placed back in the 
operating records and reposted on the website. Although it is unlikely 
that documents that were required to be prepared under the CCR 
regulations, placed in the operating record, and posted on the website 
were destroyed or discarded after the applicable retention time ran, 
this requirement nonetheless includes such documents. In other words, 
any required documents that have been destroyed or discarded must be 
reproduced and placed in the operating record and reposted on the 
facility website. Otherwise, there could be inconsistencies among the 
required facility websites totally dependent upon whether a facility 
had elected to remove documents from the website and operating record 
and not otherwise retain the documents in any facility files. EPA 
believes that allowing this inconsistency across facility websites is 
an unacceptable approach to ensuring information relevant to each CCR 
unit is publicly available.
    Finally, while the approach adopted here links retention and 
posting times to document relevance and the status of the CCR unit and 
work undertaken at the unit, EPA does not believe that the interest in 
information availability ends at the moment a unit's status changes or 
required work ends (e.g., completion of closure). Therefore, EPA is 
requiring that documents remain available for a reasonable time period 
after related milestones are reached. For many documents, EPA has 
chosen five years as the reasonable time period for document posting 
and retention after work is completed or the unit's status changes. 
This is also consistent with timeframes offered by commenters where 
specific timeframes were suggested.

   Table 3--Document Retention in the Operating Record and CCR Website
------------------------------------------------------------------------
          Document              Operating record         CCR website
------------------------------------------------------------------------
Location restrictions         Sec.   257.105(e): 5  Sec.   257.107(e): 5
 demonstration as specified    years after:          years after: CBR or
 in Sec.  Sec.   257.60-       closure by removal    post-closure care
 257.64.                       (CBR) or post-        ends.
                               closure care ends.
Landfill liner and leachate   Sec.                  Sec.
 collection preconstruction    257.105(f)(1): 5      257.107(f)(1): 5
 design certification and      years after: CBR or   years after: CBR or
 post construction             post-closure care     post-closure care
 certification as specified    ends.                 ends.
 in Sec.   257.70(e) and (f).
Documentation of liner type   Sec.                  Sec.
 as specified in Sec.          257.105(f)(2): 5      257.107(f)(3): 5
 257.71(a).                    years after: CBR or   years after: unit
                               post-closure care     ends post closure
                               ends.                 care OR liner is
                                                     removed.
Surface impoundment liner     Sec.                  Sec.
 preconstruction design        257.105(f)(3): 5      257.107(f)(2): 5
 certification and             years after: CBR or   years after: CBR or
 postconstruction              post-closure care     post-closure care
 certification as specified    ends.                 ends OR liner is
 in Sec.   257.72(c) and (d).                        removed.
Documentation that permanent  Sec.                  N/A.
 identification marker was     257.105(f)(4): 5
 installed as specified in     years after: CBR or
 Sec.  Sec.   257.73(a)(1)     post-closure care
 and 257.74(a)(1).             ends.
The initial and periodic      Sec.                  Sec.
 hazard potential              257.105(f)(5):        257.107(f)(4):
 classification assessments    Retain all versions.  Current and
 as specified in Sec.  Sec.   CBR Until closure is   previous one.
  257.73(a)(2) and             complete not         CBR Until closure is
 257.74(a)(2).                 including meeting     complete not
                               GWPS.                 including meeting
                              Closure in place       GWPS.
                               (CIP): until post-   CIP: Until post
                               closure care is       closure care is
                               complete.             complete.
The emergency action plan,    Sec.                  Sec.
 and any revisions of it, as   257.105(f)(6):        257.107(f)(5):
 specified in Sec.  Sec.       Retain all.           Current version, if
 257.73(a)(3) and             5 years after: CBR     EAP is required.
 257.74(a)(3).                 not including
                               meeting GWPS or
                               unit ends post-
                               closure care.

[[Page 39091]]

 
Documentation prepared by     Sec.                  Sec.
 the owner or operator         257.105(f)(7):        257.107(f)(6):
 recording the annual face-    Retain all.           Current version, if
 to-face meeting or exercise  5 years after: CBR     EAP is required.
 between representatives of    or unit ends post
 the owner or operator of      closure care.
 the CCR unit and the local
 emergency responders, as
 specified in Sec.  Sec.
 257.73(a)(3)(i)(E) and
 257.74(a)(3)(i)(E).
Documentation prepared by     Sec.                  Sec.
 the owner or operator         257.105(f)(8):        257.107(f)(7): Any
 recording any activation of   Retain all.           documentation
 the emergency action plan,   5 years after: CBR     prepared in the
 as specified in Sec.  Sec.    or unit ends post     last five years; if
  257.73(a)(3)(v) and          closure care.         no activation in
 257.74(a)(3)(v).                                    the last 5 years, a
                                                     statement posted
                                                     relating that
                                                     information.
The history of construction,  Sec.                  Sec.
 and any revisions of it as    257.105(f)(9):        257.107(f)(8): Only
 specified in Sec.             Retain all.           most recent and any
 257.73(c).                   5 years after: CBR     revisions from the
                               or unit ends post     last 5 years.
                               closure care.        5 years after: CBR
                                                     or unit ends post
                                                     closure care.
The initial and periodic      Sec.                  Sec.
 structural stability          257.105(f)(10):       257.107(f)(9):
 assessments as specified in   Retain all.           Current and
 Sec.  Sec.   257.73(d) and   CBR Until closure is   previous one.
 257.74(d).                    complete not         CBR Until closure is
                               including meeting     complete not
                               GWPS.                 including meeting
                              CIP: Until post        GWPS.
                               closure care is      CIP: Until post
                               complete.             closure care is
                                                     complete.
The documentation detailing   Sec.                  Sec.
 the corrective measures       257.105(f)(11):       257.107(f)(10):
 taken to remedy the           Retain all.           Current and any
 structural stability         5 years after: CBR     corrective
 deficiency for existing or    or unit ends post     measures.
 new surface impoundments as   closure care.        5 years after: CBR
 specified in Sec.  Sec.                             or unit ends post
 257.73(d)(2) and                                    closure care.
 257.74(d)(2).
The initial and periodic      Sec.                  Sec.
 safety factor assessments     257.105(f)(12):       257.107(f)(11):
 as specified in Sec.  Sec.    Retain all.           Current and
  257.73(e) and 257.74(e).    5 years after: CBR     previous one.
                               or unit ends post    5 years after: CBR
                               closure care.         or unit ends post
                                                     closure care.
The design and construction   Sec.                  Sec.
 plans of the unit, and any    257.105(f)(13):       257.107(f)(12):
 revisions of the plans as     Retain all.           Current and
 specified in Sec.            5 years after: CBR     previous one.
 257.74(c).                    or unit ends post    5 years after: CBR
                               closure care.         or unit ends post
                                                     closure care.
The application and any       Sec.                  Sec.
 supplemental materials        257.105(f)(14): 5     257.107(f)(13): 5
 submitted in support of the   years after: CBR or   years after: CBR or
 alternative liner             unit ends post        unit ends post
 demonstration application     closure care.         closure care.
 as specified in Sec.
 257.71(d)(1)(i)(E).
CCRMU Facility Evaluation     Sec.                  Sec.
 Report Document Part 1 as     257.105(f)(25): 5     257.107(f)(24): 5
 specified in Sec.             years after: CBR or   years after: CBR or
 257.75(c).                    unit ends post        unit ends post
                               closure care.         closure care.
CCRMU Facility Evaluation     Sec.                  Sec.
 Report Document Part 2 as     257.105(f)(26): 5     257.107(f)(25): 5
 specified in Sec.             years after: CBR or   years after: CBR or
 257.75(d).                    unit ends post        unit ends post
                               closure care.         closure care.
The decision on the           Sec.                  Sec.
 alternative liner             257.105(f)(19): 5     257.107(f)(18): 5
 application as specified in   years after: CBR or   years after: CBR or
 Sec.   257.71(d)(2)(iii)(F).  unit ends post        unit ends post
                               closure care.         closure care.
The CCR fugitive dust         Sec.                  Sec.
 control plan, or any          257.105(g)(1):        257.107(g)(1): Only
 subsequent amendment of the   Retain all until      most recent.
 plan as specified in Sec.     last CCR unit at     Retain until last
 257.80(b).                    the facility          unit completes post
                               completes post        closure care or
                               closure care or CBR.  CBR.
The annual CCR fugitive dust  Sec.                  Sec.
 control report as specified   257.105(g)(2):        257.107(g)(2):
 in Sec.   257.80(c).          Retain all until      Current plus last 5
                               last CCR unit at      years.
                               the facility         Retain until last
                               completes post        unit completes post
                               closure care or CBR.  closure care or
                                                     CBR.
The initial and periodic run- Sec.                  Sec.
 on and run-off control        257.105(g)(3): Only   257.107(g)(3):
 system CCR landfill plans     most recent.          Current plus any
 as specified in Sec.         Until 5 years after    other versions from
 257.81(c).                    closure of the        the last 5 years
                               landfill is           (if updated).
                               complete not         Until 5 years after
                               including             closure of the
                               achievement of GWPS.  landfill is
                                                     complete not
                                                     including
                                                     achievement of
                                                     GWPS.
Initial and periodic inflow   Sec.                  Sec.
 design flood control system   257.105(g)(4): Only   257.107(g)(4):
 CCR surface impoundment       most recent.          Current plus any
 plans as specified in Sec.   Until 5 years after    other versions from
  257.82(c).                   closure of the        the last 5 years
                               landfill is           (if updated).
                               complete not         Until 5 years after
                               including             closure of the
                               achievement of GWPS.  landfill is
                                                     complete not
                                                     including
                                                     achievement of
                                                     GWPS.
Documentation recording the   Sec.                  N/A.
 results of each CCR surface   257.105(g)(5):
 impoundment inspection and    Retain all until 5
 monitoring as specified in    years after closure
 Sec.   257.83(a).             is complete not
                               including
                               achievement of GWPS.
Annual CCR surface            Sec.                  Sec.
 impoundment inspection        257.105(g)(6):        257.107(g)(5):
 reports as specified in       Retain all until 5    Current plus last
 Sec.   257.83(b)(2).          years after closure   5.
                               is complete not      Retain until 5 years
                               including             after closure is
                               achievement of GWPS.  complete not
                                                     including
                                                     achievement of
                                                     GWPS.
The documentation detailing   Sec.                  Sec.
 the corrective measures       257.105(g)(7):        257.107(g)(6): Any
 taken to remedy the           Retain all until 5    corrective measures
 deficiency or release as      years after closure   until 5 years after
 specified in Sec.  Sec.       is complete not       closure is complete
 257.83(b)(5) and              including             not including
 257.84(b)(5).                 achievement of GWPS.  achievement of
                                                     GWPS.
Documentation recording the   Sec.                  N/A.
 results of weekly landfill    257.105(g)(8):
 structural weakness           Retain all until 5
 inspection as specified in    years after closure
 Sec.   257.84(a).             is complete not
                               including
                               achievement of GWPS.
Annual landfill inspection    Sec.                  Sec.
 reports as specified in       257.105(g)(9):        257.107(g)(7):
 Sec.   257.84(b)(2).          Retain all until 5    Current plus last
                               years after closure   5.
                               is complete not      Retain until 5 years
                               including             after closure is
                               achievement of GWPS.  complete not
                                                     including
                                                     achievement of
                                                     GWPS.

[[Page 39092]]

 
Annual groundwater            Sec.                  Sec.
 monitoring and corrective     257.105(h)(1):        257.107(h)(1):
 action report as specified    Retain all until 5    Current plus
 in Sec.   257.90(e).          years after the       previous 5 years.
                               last CCR unit at     Retain until 5 years
                               the facility          after last unit
                               completes post-       completes post-
                               closure care or       closure care or
                               completion of CBR     completion of CBR
                               including achieving   including achieving
                               GWPS for 3            GWPS for 3
                               consecutive years.    consecutive years.
Documentation of design,      Sec.                  N/A.
 installation, development,    257.105(h)(2): 5
 and decommissioning of any    years after CBR and
 monitoring wells,             GWPS have been met
 piezometers and other         or 5 years after
 devices as specified in in    completion of post-
 Sec.   257.91(e)(1).          closure care.
Groundwater monitoring        Sec.                  Sec.
 system certification as       257.105(h)(3): 5      257.107(h)(2): 5
 specified in Sec.             years after CBR and   years after CBR and
 257.91(f).                    GWPS have been met    GWPS have been met
                               or 5 years after      or 5 years after
                               completion of post-   completion of post-
                               closure care.         closure care.
Selection of a statistical    Sec.                  Sec.
 method certification as       257.105(h)(4): 5      257.107(h)(3): 5
 specified in Sec.             years after CBR and   years after CBR and
 257.93(f)(6).                 GWPS have been met    GWPS have been met
                               or 5 years after      or 5 years after
                               completion of post-   completion of post-
                               closure care.         closure care.
Assessment of corrective      Sec.                  Sec.
 measures as specified in      257.105(h)(10): 5     257.107(h)(8): 5
 Sec.   257.96(d).             years after CBR and   years after CBR and
                               GWPS have been met    GWPS have been met
                               or 5 years after      or 5 years after
                               completion of post-   completion of post-
                               closure care.         closure care.
Documentation recording the   Sec.                  N/A.
 public meeting for the        257.105(h)(11): 5
 corrective measures           years after CBR and
 assessment as specified in    App IV GWPS have
 Sec.   257.96(e).             been met or 5 years
                               after completion of
                               post-closure care.
Notification that the remedy  Sec.                  Sec.
 has been completed            257.105(h)(13): 5     257.107(h)(10): 5
 specified under in Sec.       years after           years after
 257.98(e).                    completion of         completion of
                               remedy.               remedy.
Demonstration supporting the  Sec.                  Sec.
 suspension of groundwater     257.105(h)(14): 5     257.107(h)(11): 5
 monitoring activities as      years after last      years after
 specified in Sec.             unit ends post        posting.
 257.90(g).                    closure care.
Written closure plan, and     Sec.                  Sec.
 any amendment of the plan     257.105(i)(4): Only   257.107(i)(4): Only
 as specified in Sec.          the most recent.      the most recent.
 257.102(b).                  5 years after CBR or  5 years after CBR or
                               5 years after post-   5 years after post-
                               closure care is       closure care is
                               complete.             complete.
Demonstration(s) for a time   Sec.                  Sec.
 extension for initiating      257.105(i)(5):        257.107(i)(5):
 closure as specified in       Until notice of       Until notice of
 Sec.   257.102(e)(2)(ii)      closure completion    closure completion
 and (iii).                    is posted.            is posted.
Demonstration(s) for a time   Sec.                  Sec.
 extension for completing      257.105(i)(6): 5      257.107(i)(6): 5
 closure as specified in       years after closure   years after closure
 Sec.   257.102(f)(2)(i) and   is complete.          is complete.
 (iii).
Notification of intent to     Sec.                  Sec.
 close a CCR unit as           257.105(i)(7): 5      257.107(i)(7): 5
 specified in Sec.             years after closure   years after closure
 257.102(g).                   complete.             complete.
Notification of completion    Sec.                  Sec.
 of closure of a CCR unit as   257.105(i)(8): 5      257.107(i)(8): 5
 specified in Sec.             years after unit      years after unit
 257.102(h).                   ends post closure     ends post closure
                               care or CBR.          care or CBR
Notification recording a      Sec.                  Sec.
 notation on the deed as       257.105(i)(9): 5      257.107(i)(9): 5
 specified in Sec.             years after unit      years after unit
 257.102(i).                   ends post closure     ends post closure
                               care.                 care.
Notification of intent to     Sec.                  Sec.
 comply with the alternative   257.105(i)(10): 5     257.107(i)(10): 5
 closure requirements for      years after the       years after the
 landfills as specified in     unit completes        unit completes
 Sec.   257.103(c)(1).         closure.              closure.
Annual progress reports       Sec.                  Sec.
 under the alternative         257.105(i)(11): 5     257.107(i)(11): 5
 closure requirements for      years after the       years after the
 landfills as specified in     unit completes        unit completes
 Sec.   257.103(c)(2).         closure.              closure.
Written post-closure plan,    Sec.                  Sec.
 and any amendment of the      257.105(i)(12): 5     257.107(i)(12): 5
 plan as specified in Sec.     years after unit      years after unit
 257.104(d).                   ends post closure     ends post closure
                               care.                 care.
Notification of completion    Sec.                  Sec.
 of post-closure care as       257.105(i)(13): 5     257.107(i)(13): 5
 specified in Sec.             years after unit      years after unit
 257.104(e).                   ends post closure     ends post closure
                               care.                 care.
Notification of intent to     Sec.                  Sec.
 comply with the site-         257.105(i)(14): 5     257.107(i)(14): 5
 specific alternative to       years after: CBR or   years after: CBR or
 initiation of closure due     unit ends post        unit ends post
 to development of             closure care.         closure care.
 alternative capacity
 infeasible as specified in
 Sec.   257.103(f)(1)(ix)(A).
Approved or denied            Sec.                  Sec.
 demonstration for the site-   257.105(i)(15): 5     257.107(i)(15): 5
 specific alternative to       years after: CBR or   years after: CBR or
 initiation of closure due     unit ends post        unit ends post
 to development of             closure care.         closure care.
 alternative capacity
 infeasible as specified in
 Sec.   257.103(f)(1)(ix)(B).
Notification for requesting   Sec.                  Sec.
 additional time to the        257.105(i)(16): 5     257.107(i)(16): 5
 alternative cease receipt     years after: CBR or   years after: CBR or
 of waste deadline as          unit ends post        unit ends post
 specified in Sec.             closure care.         closure care.
 257.103(f)(1)(ix)(C).
Semi-annual progress reports  Sec.                  Sec.
 for the site-specific         257.105(i)(17): 5     257.107(i)(17): 5
 alternative to initiation     years after: CBR or   years after: CBR or
 of closure due to             unit ends post        unit ends post
 development of alternative    closure care.         closure care.
 capacity infeasible as
 specified in Sec.
 257.103(f)(1)(xi).
Notification of intent to     Sec.                  Sec.
 comply with the site-         257.105(i)(18): 5     257.107(i)(18): 5
 specific alternative to       years after: CBR or   years after: CBR or
 initiation of closure due     unit ends post        unit ends post
 to permanent cessation of a   closure care.         closure care.
 coal-fired boiler(s) by a
 date certain as specified
 in Sec.
 257.103(f)(1)(viii).

[[Page 39093]]

 
Approved or denied            Sec.                  Sec.
 demonstration for the site-   257.105(i)(19): 5     257.107(i)(19): 5
 specific alternative to       years after: CBR or   years after: CBR or
 initiation of closure due     unit ends post        unit ends post
 to permanent cessation of a   closure care.         closure care.
 coal-fired boiler(s) by a
 date certain as specified
 in Sec.   257.103(f)(2)(ix).
Annual progress report for    Sec.                  Sec.
 the site-specific             257.105(i)(20): 5     257.107(i)(20): 5
 alternative to initiation     years after: CBR or   years after: CBR or
 of closure due to permanent   unit ends post        unit ends post
 cessation of a coal-fired     closure care.         closure care.
 boiler(s) by a date certain
 as specified in Sec.
 257.103(f)(2)(x).
Legacy Applicability Report   Sec.                  Sec.
 as specified in Sec.          257.105(k)(1): 5      257.107(k)(1): 5
 257.100(f)(1)(i).             years after: CBR or   years after: CBR or
                               unit ends post        unit ends post
                               closure care.         closure care.
------------------------------------------------------------------------

IV. Effect on State CCR Permit Programs

    In the proposed rule, EPA discussed the effect of the amended 
regulations on State CCR permit programs. The revisions to the CCR 
regulations both establish standards for new types of units and revise 
existing requirements for CCR units defined in and subject to the 2015 
CCR Rule. For this reason, the requirements for approval and retention 
of a State CCR permit program in accordance with RCRA section 4005(d) 
will change. How these revisions will affect States depends on whether 
the State has received approval for the provisions that are ultimately 
included in any final rule and whether the State is seeking full or 
partial approval of its permit program.
    EPA received several comments asking for clarification on what 
States need to do to adopt these revisions. As EPA explained in the 
proposed rule, if a State has an approved program pursuant to RCRA 
section 4005(d), that State program will continue to operate in lieu of 
the portions of the Federal program adopted by the State, even if EPA 
revised the Federal analog of that regulation in this final action. See 
42 U.S.C. 6945(d)(1)(A), (3). This means that the applicable revisions 
to the Federal CCR regulations will only take effect in an approved 
State when the State revises its program to adopt them. For this 
reason, RCRA requires a State to revise its program within three years 
of any applicable revision to the Federal CCR regulation that is more 
protective than the existing State program in order to maintain 
approval. See, 42 U.S.C. 6945(d)(1)(D)(i)(II). Conversely, the Federal 
requirements continue to apply directly to CCR facilities in States 
without an approved CCR program and in States with a partial CCR 
program. EPA will work with each State that is interested in adopting 
these regulations to ensure the State CCR permit program is at least as 
protective as the Federal program. If a State chooses not to adopt 
certain portions of this final rule, when EPA establishes a Federal CCR 
permit program, EPA will begin issuing permits for CCR units, legacy 
CCR surface impoundments, and CCRMU in nonparticipating States.
    As discussed in Units III.A. and III.B of this preamble, EPA is 
establishing requirements for legacy CCR surface impoundments and 
CCRMU. Because legacy CCR surface impoundments and CCRMU are new types 
of Federally regulated units, no State is currently approved to issue 
State CCR permits to such units in lieu of the Federal CCR regulations. 
Thus, any State that wants approval to issue permits to such units will 
be required to update the State CCR regulations and go through the 
State CCR permit program approval process set forth in RCRA section 
4005(d).
    As discussed in Units III.B.g and III.D of this preamble, EPA is 
also revising requirements under the existing CCR regulations. The 
revised requirements will directly apply to affected facilities except 
to the extent EPA has already approved the State to issue permits for 
the original requirement. In such a case, the State requirement will 
apply in lieu of the new Federal requirement until the State program is 
revised. certain provisions (i.e., the requirement to expand Sec.  
257.102(d)(2) to landfills that are inundated with groundwater, 
document retention timeframes) to be more protective
    One commenter asked if a State can adopt regulations for either 
legacy CCR surface impoundments or CCRMU, but not both. EPA issued the 
Coal Combustion Residuals State Permit Program Guidance Document; 
Interim Final (82 FR 38685, August 15, 2017) (the ``Guidance 
Document'') to advise States interested in developing a State CCR 
permit program for approval by EPA. The Guidance Document explains the 
process for developing a State CCR permit program and expressly 
contemplates a State requesting partial approval of such a program. 
Thus, a State may request approval of the final rule provisions 
applicable to either or both the legacy CCR surface impoundments and 
the CCRMU requirements.
    Some commenters discussed the process for approving State CCR 
permit programs and inquired about the number of States that EPA is 
currently working with and the timeframe for approval of a State 
program package. As noted above, the Guidance Document explains the 
process for States to develop of State CCR permit program. The time it 
takes to develop an approvable State program depends on a number of 
factors, including the time it takes for a State to promulgate or enact 
regulations that are as protective as the Federal CCR regulations. Once 
the State has a complete and approvable program, EPA will issue the 
final program determination within 180 days of determining that the 
State's submission is complete. EPA commits to working with States to 
adopt regulations that are at least as protective as the Federal CCR 
regulations and to review any draft application materials and provide 
comments to ensure the final application package can go through EPA's 
approval process in a timely manner. The process for approving program 
modifications is the same as for the initial program approval: EPA will 
propose to approve or deny the program modification and hold a public 
hearing during the comment period. EPA will then issue the final 
program determination within 180 days of determining that the State's 
submission is complete.
    Finally, EPA received comments saying that EPA seems to be 
finalizing these regulations under the self-implementing regulatory 
scheme that existed when the 2015 CCR rule was promulgated. The 
comments further say that since then, Congress enacted the WIIN Act, 
which fundamentally changed the regulatory landscape and now requires 
implementation through

[[Page 39094]]

State and Federal permit programs. EPA acknowledges this Congressional 
mandate and is working to finalize the Federal CCR permit program in 
addition to approving State permit programs. States have requested that 
EPA finalize the legacy CCR surface impoundment provisions and other 
provisions that were remanded back to the Agency to allow States to 
apply for full program approval. EPA disagrees that the self-
implementing rule is inappropriate in lieu of the WIIN Act requirements 
because all owners and operators of CCR units and CCRMU will need to 
follow the self-implementing rule until they obtain a State or Federal 
permit. Lastly, any permits that are issued by EPA will refer to the 
regulatory requirements in 40 CFR part 257, subpart D, or the 
equivalent State regulation in the case of State permits.

V. The Projected Economic Impact of This Action

A. Introduction

    EPA estimated the costs and benefits of this action in a Regulatory 
Impact Analysis (RIA), which is available in the docket for this 
action.

B. Affected Universe

    The universe of facilities and units affected by the final rule 
includes four categories. The first is comprised of facilities with 
legacy CCR surface impoundments. The RIA identifies 194 legacy CCR 
surface impoundments located at 84 facilities. The second component of 
the affected universe is composed of CCRMU. The RIA identifies 195 
CCRMU at 104 facilities. The third component of the affected universe 
is composed of CCRMU at ``other active facilities,'' or OAFUs. The RIA 
identifies 15 OAFUs at six facilities. The final component of the 
universe is comprised of CCR landfills that are already regulated under 
the 2015 CCR Rule, but which have waste in contact with groundwater. 
The RIA identifies 39 such landfills at 33 facilities.

C. Baseline Costs

    The RIA examines the extent to which baseline practices at legacy 
CCR surface impoundments and CCRMU address contamination in a manner 
consistent with the requirements of the final rule. To the extent that 
legacy CCR surface impoundments and CCRMU are already sufficiently 
addressing contamination, they are assumed to not incur costs or 
realize benefits under the final rule. To estimate the proportion of 
legacy CCR surface impoundments addressing contamination in the 
baseline, the RIA examines relevant Federal and State programs and 
determines that about 9.8% of legacy CCR surface impoundments are 
addressing site contamination. To estimate the proportion of CCRMU 
addressing contamination, the RIA examines publicly available filings 
from owners and operators of regulated coal-fired power plants. The RIA 
estimates that about 20.8% of CCRMU are undergoing sitewide corrective 
action and closure in a manner sufficient to meet the requirements of 
the final rule.

D. Costs and Benefits of the Final Rule

    The RIA estimates that the annualized costs of this action will be 
approximately $214-$240 million per year when discounting at 2%. Of 
this, $123-$135 million is attributable to the requirements for legacy 
CCR surface impoundments, which are subject to the D.C. Circuit's order 
in USWAG, $79-$92 million is attributable to the requirements for 
CCRMU, $8-$9 million is attributable to the requirements for OAFUs, and 
$4 million is attributable to requirements for landfills. The costs of 
this final rule are discussed further in the RIA and include the costs 
of unit closure, corrective action, fugitive dust controls, structural 
integrity inspections, and recordkeeping and reporting.
    The RIA estimates that the annualized monetized benefits 
attributable to this action will be approximately $53-$80 million per 
year when discounting at 2%. Of this, $43-$57 million is attributable 
to the requirements for legacy CCR surface impoundments, $9-$21 million 
is attributable to the requirements for CCRMU, $1-$2 million is 
attributable to the requirements for CCRMU at ``other active 
facilities,'' or OAFUs. Requirements for landfills account for a de 
minimis amount of benefits. The monetized benefits of this proposed 
rule are discussed further in the RIA, and include reduced incidents of 
cancer from the consumption of arsenic in drinking water, avoided 
intelligence quotient (IQ) losses from mercury and lead exposure, non-
market benefits of water quality improvements, and the protection of 
threatened and endangered species. EPA also monetized the benefits of 
avoided impoundment failures, including both ``catastrophic'' failures 
and smaller-volume releases. One example of a severe impoundment 
failure is the Dan River Steam Station failure that occurred in 2014, 
when a stormwater drainage pipe under the inactive surface impoundments 
at the Dan River Steam Station caused the inadvertent release of 39,000 
tons of CCR directly into the nearby Dan River. The resulting high-end 
estimate of the costs of this impoundment failure is $300 million.
    The monetized benefits in the RIA are incomplete and omit 
categories of benefits that are known to be significant. One such 
category of benefits is avoided cases of lung and bladder cancers due 
to exposure to arsenic III and arsenic V. Inorganic arsenic is known to 
occur in CCRs, and can leach into drinking water from leaking CCR 
disposal units. The EPA IRIS Toxicological Review of Inorganic Arsenic 
(CASRN 7440-38-2) draft, published in October 2023, provides updated 
toxicity values for cancer outcomes associated with inorganic arsenic 
exposure. From these values the benefits of avoided cancer cases can be 
monetized. The RIA does not consider these avoided cancer benefits in 
the main analysis because the IRIS report underlying them is still 
draft and subject to revision. These benefits are instead monetized in 
a sensitivity analysis and are estimated to be $19 million per year 
when discounting at 2%. As these benefits are but two health endpoints 
from a single contaminant, they point to the possible true magnitude of 
benefits attributable to the final rule.
    The RIA also describes a number of important benefits that cannot 
currently be quantified or monetized due to data limitations or 
limitations in current methodologies. These benefits include reducing 
the baseline risk of unit leakage and failure attributable to climate-
change driven severe weather events. Many legacy CCR surface 
impoundments and CCRMU are situated close to rivers or are located 
along the coast. These units are vulnerable to inland or coastal 
flooding, which may occur at an increased frequency due to the effects 
of climate change. Flooding events may cause these units to overtop or 
catastrophically collapse, releasing CCR into the environment, exposing 
nearby communities to toxic contamination and necessitating potentially 
costly cleanup and remediation. EPA has identified 62 legacy CCR 
impoundments at medium or high risk from climate change-driven 
flooding, and 74 CCRMU at medium or high risk from climate change 
driven-flooding.
    Another set of benefits outside the scope of quantification include 
reducing the instance of negative human health impacts such as 
cardiovascular mortality, neurological effects, and cancers (separate 
from the quantified cancer benefits) brought on by exposure to toxins 
found in coal ash. Either through leaking impoundment sites or release 
events, many pollutants from legacy CCR surface impoundments are

[[Page 39095]]

likely to contaminate nearby water bodies, affecting surface waters, 
local fish populations, and drinking water reservoirs. Because known 
transport pathways exist between these release events and human health 
endpoints, EPA expects the proposed rule to cause risk reductions for 
various categories that are not yet quantifiable. Toxins such as 
thallium, molybdenum, and lithium, while all present in CCR, lack the 
data to create dose-response relationships between ingestion rates and 
specific health endpoints, and thus precludes EPA from quantifying 
associated benefits.
    The RIA describes several surface water quality benefits such as 
the improved health of ecosystems proximate to CCR disposal units, and 
the avoided costs of treating public drinking water impacted by CCR 
contamination. EPA expects leakages or releases of effluent from any 
CCR surface impoundment site to contaminate nearby surface waters and 
environments. Introduction of arsenic, selenium, and other heavy metals 
associated with CCR surface impoundment contents are shown to 
accumulate in sediments of nearby stream and lake beds, posing risks 
and injury to organisms and consequently ecosystems. Although surface 
waters are broadly protected from high levels of contaminants under 
EPA's regulations and Water Quality Criteria (WQC), complex 
interactions from trace amounts of heavy metals and other toxins known 
to be released from legacy CCR surface impoundment sites have displayed 
measurable impact to aquatic animals and ecosystems.\152\
---------------------------------------------------------------------------

    \152\ Brandt, Jessica E., et al. ``Beyond selenium: coal 
combustion residuals lead to multielement enrichment in receiving 
lake food webs.'' Environmental science & technology 53.8 (2019): 
4119-4127.
---------------------------------------------------------------------------

    The RIA discusses how the final rule may result in avoided drinking 
water treatment costs and drinking water quality improvements at public 
water systems. First, by reducing the risk of CCR leakage events and 
impoundment failures, the proposed rule will help avoid costs of water 
quality treatment at public intake sources. Second, by preventing 
release events the proposed rule has the potential to reduce the 
incidence of eutrophication in source waters for public drinking 
supplies. Eutrophication is primarily caused by an overabundance of 
nitrogen and phosphorus. It causes foul tastes and odors, which require 
additional treatment, and commensurate expenditure, to remove.
    The RIA discusses potential impacts on the market for the 
beneficial use of CCR as a substitute for virgin materials. Future uses 
of CCR are unknown. Research on the recovery of rare earth elements and 
yttrium from coal fly ash is ongoing but currently only at laboratory 
scale. It is possible that in the future, the availability of 
additional CCR may reach an equilibrium price that encourages demand, 
particularly as coal plants retire and the supply of ``new'' CCR falls. 
However, the quality of CCR in legacy CCR surface impoundments and 
CCRMU may limit their value. Older, closed impoundments or other CCR 
storage areas are less likely to have CCR material of a known and 
reliable composition.
    The RIA also discusses potential reductions in fugitive dust 
emanating from legacy CCR surface impoundments, which will benefit 
fence line communities by reducing the amount of resuspended ash from 
legacy CCR surface impoundments that could otherwise lead to 
respiratory health hazards for communities surrounding a given legacy 
impoundment.
    The RIA discusses the benefits of improved property values near 
closed and remediated sites. Neighborhoods located near hazardous waste 
sites often experience depressed property values due to health risks 
posed by contaminant exposure pathways, potential reductions in 
ecological services, unsightly aesthetics of the disposal unit site, 
and potential stigma associated with proximity to a disposal site. 
Almost a million households, and over 2.5 million people are located 
within three miles of legacy CCR surface impoundments and CCRMU. 
Approximately 75,000 households and 200,000 people are located within a 
mile. Improvements in home values resulting from the proposed rule have 
the potential to bestow welfare gains to homeowners located near legacy 
CCR surface impoundments and CCRMU.
    The RIA also discusses the value of reusing land formerly occupied 
by legacy CCR surface impoundments, and CCRMU. Once legacy CCR surface 
impoundments and CCRMU are closed by removal, landfills are properly 
capped, or corrective action activities are completed, the land is more 
likely to move into alternative, economically productive purposes. For 
example, these land reuse projects might include industrial 
redevelopment or implementation of green energy generation which can 
utilize the existing electricity grid infrastructure.
    Finally, based on the demographic composition and environmental 
conditions of communities within one and three miles of legacy CCR 
surface impoundments, the final rule will reduce existing 
disproportionate and adverse effects on economically vulnerable 
communities, as well as those that currently face environmental 
burdens. For example, in Illinois the population living within one mile 
of legacy CCR surface impoundment sites is over three times as likely 
compared to the State average to have less than a high school education 
(35.66% compared to 10.10%, see RIA exhibit ES.14), and that population 
already experiences higher than average exposures to particulate 
matter, ozone, diesel emissions, lifetime air toxics cancer risks, and 
proximity to traffic, Superfund sites, Risk Management Plan sites, and 
hazardous waste facilities (see RIA exhibit ES.15).
    The RIA also discusses the interaction of the CCR rules with Office 
of Air rules governing emissions at power plants. Following on the 
significant progress EPA has made over many decades to reduce dangerous 
pollution from coal-fired electric utilities' stack emissions and 
effluents, this proposed rule will help EPA further ensure that the 
communities and ecosystems closest to coal facilities are sufficiently 
protected from harm from groundwater contamination, surface water 
contamination, fugitive dust, floods and impoundment overflows, and 
threats to wildlife. The volume and toxicity of CCR at many sites 
persisted or increased over past decades even as coal-fired units' air 
and water emissions decreased, and this proposed rule will help EPA 
fulfill the promise of substantial public health and welfare gains from 
its full suite of regulations aimed at reducing the harms from coal-
combustion pollution.
    As noted previously, EPA establishes the requirements under RCRA 
sections 1008(a)(3) and 4004(a) without taking cost into account. See, 
USWAG, 901 F.3d at 448-49. Although EPA has accordingly designed its 
proposal based on its statutory factors and court precedent and has not 
relied on this benefit-cost analysis in the selection of its proposed 
alternative, EPA believes that after considering all unquantified and 
distributional effects, the public health and welfare gains that will 
result from the proposed alternative would justify the rule's costs.

VI. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

[[Page 39096]]

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 14904: Modernizing Regulatory Review

    This action is a ``significant regulatory action'' under section 
3(f)(1) of Executive Order 12866, as amended by Executive Order 14094. 
Accordingly, the EPA submitted this action to the Office of Management 
and Budget (OMB) for review. Any changes made in response to 
recommendations received as part Executive Order 12866 review have been 
documented in the docket. The EPA prepared an analysis of the potential 
costs and benefits associated with this action. This analysis, 
Regulatory Impact Analysis: Hazardous and Solid Waste Management 
System: Disposal of Coal Combustion Residuals from Electric Utilities; 
Legacy CCR Surface Impoundments, is available in the docket and is 
briefly summarized in Unit V.

B. Paperwork Reduction Act (PRA)

    The information collection activities in this rule will be 
submitted for approval to the Office of Management and Budget (OMB) 
under the PRA. EPA submitted the proposed rule ICR to OMB for approval 
on March 25th, 2024, triggering a 30-day public comment period for this 
proposed information collection. EPA anticipates the final ICR will be 
approved by the effective date of this final rule. If EPA receives any 
new and substantive comments on proposed collection, i.e., substantive 
comments that were not received during the 60 day public comment period 
on the rule (from May 18, 2023-July 17, 2023), EPA will address those 
comments in a revision to the ICR via the standard PRA approval 
process. The Information Collection Request (ICR) document that the EPA 
prepared has been assigned EPA ICR number 2761.01. Due to the 
concurrent timing of this rulemaking and the timing of the renewal of 
the collection of information 2050-0223, Disposal of Coal Combustion 
Residuals From Electric Utilities, EPA is requesting a temporary OMB 
control number for this rulemaking collection, which will be assigned 
upon approval of the proposed ICR by OMB. EPA will submit a request to 
merge this rulemaking collection into the existing ICR for the program, 
2050-0223, once the final rulemaking ICR and renewal for 2050-0223 are 
approved by OMB. You can find a copy of the ICR in the docket for this 
rule, and it is briefly summarized here. The information collection 
requirements are not enforceable until OMB approves them.
    The final rule requires legacy CCR surface impoundments to comply 
with the reporting and recordkeeping requirements already in place for 
regulated CCR units. Many of these requirements are one-time 
requirements that will occur soon after the promulgation of the rule, 
while several are ongoing. The final rule also requires legacy CCR 
surface impoundments to submit an applicability report, unique to this 
universe of units, which will provide stakeholders with essential site 
characteristic and contact information for the unit.
    Respondents/affected entities: Inactive electric utility plants 
with inactive CCR surface impoundments (legacy CCR surface 
impoundments), electric utility plants with CCRMU, electric utility 
plants with OAFUs, and electric utility plants with landfills already 
subject to regulation under the 2015 final CCR rule, but which have 
waste in contact with groundwater.
    Respondent's obligation to respond: The recordkeeping, 
notification, and posting are mandatory as part of the minimum national 
criteria promulgated under Sections 1008(a), 2002(a), 4004, and 4005(a) 
and (d) of RCRA.
    Estimated number of respondents: 2,083.
    Frequency of response: one-time and annually.
    Total estimated burden: 172,909 hours (per year). Burden is defined 
at 5 CFR 1320.3(b).
    Total estimated cost: $11.2 million (per year), includes $11.2 
million annualized capital or operation and maintenance costs.
    An agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for the 
EPA's regulations in 40 CFR are listed in 40 CFR part 9. When OMB 
approves this ICR, the Agency will announce that approval in the 
Federal Register and publish a technical amendment to 40 CFR part 9 to 
display the OMB control number for the approved information collection 
activities contained in this final rule.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. The 
small entities subject to the requirements of this action are owners 
and operators of coal fired electric utility plants in NAICS code 
221112 and firms that own property on which an inactive/retired coal 
fired power plant is located. The Agency has identified 175 small 
entities subject to the final rule. The Agency estimates that the 
average annual cost to a small entity will be approximately $0.31 
million; the vast majority of these entities do not own legacy CCR 
surface impoundments, CCRMU, or OAFUs, and must only complete the 
evaluation report requirements of the final rule. EPA has identified 15 
small entities owning legacy CCR surface impoundments, CCRMU, and/or 
OAFUs; EPA assumes that small entities will not be able to pass on any 
compliance costs to ratepayers. This assumption, in EPA's opinion, 
constitutes a high-end scenario. In total, these 15 small entities are 
estimated to incur approximately $52.1 million in annual costs. The 
Agency has determined that five small entities may experience an impact 
greater than 3% of annual revenues. Details of this analysis are 
presented in the Regulatory Impact Analysis, which can be found in the 
docket for this action.

D. Unfunded Mandates Reform Act (UMRA)

    This action contains a Federal mandate under UMRA, 2 U.S.C. 1531-
1538, that may result in expenditures of $100 million or more for 
State, local and Tribal governments, in the aggregate, or the private 
sector in any one year. Accordingly, the EPA has prepared a written 
statement required under section 202 of UMRA. The statement is included 
in the docket for this action and briefly summarized here.
    The RIA estimates that the proposed rule may affect 194 legacy CCR 
surface impoundments at 84 facilities, 195 CCRMU at 104 facilities, 15 
OAFUs at six facilities, and 39 landfills already regulated under the 
2015 final rule. The final rule will extend the existing requirements 
of the 2015 CCR final rule, found in 40 CFR part 257, subpart D, to 
these units.
    In preparing the 2015 CCR final rule, and consistent with the 
intergovernmental consultation provisions of section 204 of the UMRA, 
EPA initiated pre-proposal consultations with governmental entities 
affected by the rule. In developing the regulatory options for the 2015 
CCR Rule, EPA consulted with small governments according to EPA's UMRA 
interim small government consultation plan developed pursuant to 
section 203 of UMRA. The details of this consultation can be found in 
the preamble to the 2015 CCR final rule. Consistent with section 205 of 
UMRA, EPA identified and considered a reasonable number of regulatory 
alternatives, and adopted the least-costly approach (i.e., a modified 
version

[[Page 39097]]

of the ``D Prime'' least costly approach presented in the 2010 proposed 
CCR rule). The final rule merely extends the provisions of the 2015 
final rule to four additional classes of facilities.
    This action is not subject to the requirements of section 203 of 
UMRA because it contains no regulatory requirements that might 
significantly or uniquely affect small governments. The threshold 
amount established for determining whether regulatory requirements 
could significantly affect small governments is $100 million annually. 
The RIA estimates annual average costs of $7 million total for the four 
local governments identified as owning units subject to the final rule. 
These estimates are well below the $100 million annual threshold 
established under UMRA. There are no known Tribal owner entities of 
facilities that would incur substantial direct costs under the final 
rule.

E. Executive Order 13132: Federalism

    This action does not have Federalism implications. It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have Tribal implications as specified in 
Executive Order 13175. For the ``Final Rule: Hazardous and Solid Waste 
Management System; Disposal of Coal Combustion Residuals from Electric 
Utilities'' published April 17, 2015 (80 FR 21302), EPA identified 
three of the 414 coal-fired electric utility plants (in operation as of 
2012) as being located on Tribal lands. To the extent that these plants 
contain CCRMU subject to the proposed rule, the impacts to Tribes will 
be limited to document review and walking the site. As these are not 
substantial direct costs, this action does not impose substantial 
direct compliance costs or otherwise have a substantial direct effect 
on one or more Indian Tribes, to the best of EPA's knowledge. Neither 
will it have substantial direct effects on the relationship between the 
Federal Government and Indian Tribes, or on the distribution of power 
and responsibilities between the Federal Government and Indian Tribes. 
Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    Executive Order 13045 directs Federal agencies to include an 
evaluation of the health and safety effects of the planned regulation 
on children in Federal health and safety standards and explain why the 
regulation is preferable to potentially effective and reasonably 
feasible alternatives. This action is subject to E.O. 13045 (62 FR 
19885, April 23, 1997) because it is a significant regulatory action 
under section 3(f)(1) of E.O. 12866, and EPA believes that the 
environmental health or safety risks addressed by this action may have 
a disproportionate effect on children. In addition, EPA's Policy on 
Children's Health applies. Accordingly, EPA evaluated the environmental 
health or safety effects of CCR constituents of potential concern on 
children. The results of this evaluation are contained in the Human and 
Ecological Risk Assessment of Coal Combustion Wastes available in the 
docket for this action.
    As ordered by E.O. 13045 Section 1-101(a), EPA identified and 
assessed environmental health risks and safety risks that may 
disproportionately affect children in the revised risk assessment. 
Pursuant to U.S. EPA's Guidance on Selecting Age Groups for Monitoring 
and Assessing Childhood Exposures to Environmental Contaminants, 
children are divided into seven distinct age cohorts: 1 to <2 yr, 2 to 
<3 yr, 3 to <6 yr, 6 to <11 yr, 11 to <16 yr, 16 to <21 yr, and infants 
(<1 yr). Using exposure factors for each of these cohorts, EPA 
calculated cancer and non-cancer risk results in both the screening and 
probabilistic phases of the assessment. In general, risks to infants 
tended to be higher than other childhood cohorts, and also higher than 
risks to adults. However, for drinking water cancer risks, the longer 
exposure periods for adults led to the highest risks over a standard 
adult lifetime. Screening risks exceeded EPA's human health criteria 
for children exposed to contaminated air, soil, and food resulting from 
fugitive dust emissions and run-off. Similarly, 90th percentile child 
cancer and non-cancer risks exceeded the human health criteria for the 
groundwater to drinking water pathway under the full probabilistic 
analysis (Table 5-17 in the Human and Ecological Risk Assessment of 
Coal Combustion Wastes). The closure, groundwater monitoring and 
corrective action required by the rule will reduce risks from currently 
unregulated legacy CCR surface impoundments, and CCRMU. Thus, EPA 
believes that this rule will be protective of children's health.
    In general, because the pollution control requirements under the 
CCR rule will reduce health and environmental exposure risks at all 
coal-fired electric utility plants, the CCR rule is not expected to 
create additional or new risks to children.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution or Use

    This action is not a ``significant energy action'' because it is 
not likely to have a significant adverse effect on the supply, 
distribution or use of energy. Because the final rule addresses 
management of CCR and pertains mainly to inactive CCR units (legacy CCR 
surface impoundments at inactive facilities and CCRMU at facilities 
already regulated under the 2015 CCR rule), this final rule will have 
no effect on the production of crude oil, coal, fuel, or natural gas. 
In addition, the final rule will have no direct effect on electricity 
production, generating capacity, or on foreign imports or exports of 
energy.
    Electricity price effects on the price of energy are only possible 
because in some cases, utilities may attempt to pass the costs of 
managing CCR under the proposed rule on to ratepayers in the form of 
increased electricity rates through Public Utility Commissions (PUCs). 
As a result, the final rule may indirectly affect electricity prices 
within the energy sector. To estimate what the electricity price 
effects of this final rule may be on a national level, EPA compared the 
expected costs of this rule to the expected costs and effects resulting 
from three previously conducted IPM runs for three previous RIAs, the 
2015 CCR Rule, the 2015 ELG Rule (which included the costs of the 2015 
CCR Rule in its baseline), and the 2019 ELG Rule, which was a 
deregulatory rule. Extrapolating from these IPM runs, EPA estimates 
that the effect of the current action on electricity prices will be 
between 0.060% and 0.156%. Since these effects fall below the 1% 
threshold, EPA concludes that this rule is not expected to generate 
significant adverse energy effects. The full energy impacts analysis is 
available in the Regulatory Impact Analysis that accompanies this 
action.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking involves technical standards. The EPA has decided 
to use technical standards in this rule as the existing CCR regulations 
rely on the

[[Page 39098]]

following: (1) RCRA Subpart D, Section 257.70 liner design criteria for 
new CCR landfills and any lateral expansion of a CCR landfill includes 
voluntary consensus standards developed by ASTM International and EPA 
test methods such as SW-846, (2) Section 257.71 liner design criteria 
for existing CCR surface impoundments includes voluntary consensus 
standards developed by ASTM International and EPA test methods such as 
SW-846, (3) Section 257.72 liner design criteria for new CCR surface 
impoundments and any lateral expansion of a CCR surface impoundment 
includes voluntary consensus standards developed by ASTM International 
and EPA test methods such as SW-846, and (4) Section 257.73 structural 
stability standards for new and existing surface impoundments use the 
ASTM D 698 and 1557 standards for embankment compaction. In this 
rulemaking, EPA expands the application of Sec.  257.73 structural 
stability standards, which as noted, rely on the ASTM D 698 and 1557 
standards for embankment compaction, to facilities with legacy CCR 
surface impoundments. This rulemaking does not adopt or otherwise 
involve any additional technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations and 
Executive Order 14096: Revitalizing Our Nation's Commitment to 
Environmental Justice for All

    EPA believes that the human health or environmental conditions that 
exist prior to this action result in or have the potential to result in 
disproportionate and adverse human health or environmental effects on 
communities with environmental justice concerns.
    EPA conducted a demographic screening analysis for all facilities 
subject to the rule to determine the composition of populations living 
within one and three miles of facilities with these units. 
Specifically, EPA looked at the percentages of the relevant populations 
that are identified as minority/people of color, households below the 
Federal poverty level, population with less than high school education 
(among those 25 years and older), and populations characterized by 
linguistic isolation. EPA chose to look at radii of one and three miles 
because they represent the areas most likely to be affected by 
groundwater contamination and surface water impacts from legacy CCR 
surface impoundments and CCRMU. EPA compared the demographic profile 
within these radii to national and State averages to assess the extent 
to which marginalized groups are disproportionately affected by CCR-
related contamination in the baseline.
    To more fully explore the conditions in communities and populations 
surrounding facilities subject to the 2024 final rule, EPA expanded the 
demographic proximity analysis to include a suite of metrics that 
represent baseline health and social factors that are likely to be 
affected by, or interact with, changes in the management of facilities 
as a result of the rule. This analysis also focuses on populations 
within one mile of legacy CCR surface impoundments and CCRMU sites, but 
includes a combination of eight baseline indicators from the CDC 
Environmental Justice Index (EJI) and EPA's EJScreen that document 
community conditions that (a) suggest potential environmental justice 
concerns and (b) are relevant to actions resulting from the 2024 final 
rule. These include:
     CDC EJI Indicators: Lack of internet access, prevalence of 
disabilities, cancer, poor mental health, high blood pressure, asthma, 
and diabetes.
     EJScreen Indicators: PM2.5 concentrations and 
low life expectancy.
    This specific subset of indicators captures health-related risks, 
environmental burdens, and access to information that affect a 
substantial number of communities living near the universe of 
facilities to provide a clearer picture of the baseline conditions. To 
assess the extent to which facilities affected by the final rule are 
located within communities with high baseline risks, the analysis 
specifically identifies, for each indicator, communities that fall in 
the highest (most at risk) 40 percent, or top two quintiles of 
communities nationwide. In other words, the analysis only identifies 
instances where a community is more at risk or more burdened than 60 
percent of all communities in the U.S. For each indicator, the analysis 
calculates the number of communities within one mile of legacy CCR 
surface impoundments, CCRMU, and OAFU facilities that are in the top 
two quintiles.
    Many of the health-related indicators appeared in communities with 
high percentiles for other health-related indicators, especially 
combinations of high blood pressure, diabetes, and asthma. Communities 
with high populations of people with disabilities were also likely to 
have high prevalence of high blood pressure, asthma, diabetes, poor 
mental health, and cancer. Additionally, high prevalence of poor mental 
health and lack of internet accompanied prevalence of morbidities 
besides cancer.
    EPA also identified lack of internet access, which is generally 
associated with poverty but also is a distinct factor in ensuring that 
information about regulated facilities and units that is required by 
the 2024 final rule is accessible to the people in surrounding 
communities. Half of the facilities with a lack of internet access in 
surrounding communities were also above two times the State average for 
households below the national poverty level, but the other half are 
not, suggesting that this barrier to information may be more widespread 
and less predictable in the 2024 rule context. In addition to the 
income-related implications, lack of internet access has consequences 
for information access that are pertinent to the 2024 final rule, which 
requires facilities to publish information online for public access. 
Therefore, a lack of internet access is a key barrier for communities 
who may be unable to receive important information.
    These analyses found that of the roughly 182 sites in the regulated 
universe, more than half are located in areas with environmental 
justice concerns in surrounding communities. These communities are 
likely to face existing environmental burdens, economic stressors, and 
health conditions that put their residents and ecosystems at greater 
cumulative risk from the impacts associated with proximity to legacy 
impoundments. Because the final rule is designed to both prevent future 
contamination and eliminate existing contamination from CCR units that 
are near these already-vulnerable communities, EPA believes that the 
rule is likely to incrementally reduce existing disproportionate and 
adverse effects on communities with EJ concerns. EPA believes that the 
rule is particularly likely to reduce disproportionate and adverse 
effects on people of color and populations who experience low income. 
The rule improves overall environmental quality for all exposed 
communities and populations by ensuring protection and remediation of 
groundwater, resulting in avoided health effects (including cancer) 
from drinking water exposures to arsenic and other contaminants, and by 
reducing releases of CCR from impoundments into the surface waters, 
ecosystems, and air surrounding the facilities. The final rule is 
equity-enhancing in that it addresses EJ concerns present in the 
communities and populations near many of the facilities by reducing 
environmental and health burdens that contribute to the cumulative 
impacts experienced by

[[Page 39099]]

these communities, including the often-costly burdens associated with 
health effects. Moreover, the rule requires that facilities make 
information about their contamination and remediation actions available 
on public websites; this provides all interested members of the public, 
including communities with EJ concerns, improved access to information 
related to their environment or health, supporting effective community 
involvement.
    Overall, EPA found that facilities affected by the rule are often 
located near populations of color with higher rates of poverty and 
linguistic isolation, and lower levels of education. Of the roughly 182 
sites in the regulated universe, more than half are located in areas 
with environmental justice concerns in surrounding communities. These 
communities are likely to face existing environmental burdens, economic 
stressors, and health conditions that put their residents and 
ecosystems at greater cumulative risk from the impacts associated with 
proximity to legacy impoundments. Because the final rule is designed to 
both prevent future contamination and eliminate existing contamination 
from CCR units that are near these already-vulnerable communities, EPA 
believes that the rule is likely to incrementally reduce existing 
disproportionate and adverse effects on communities with EJ concerns. 
EPA believes that the rule is particularly likely to reduce 
disproportionate and adverse effects on people of color and populations 
who experience low income.
    The information supporting this Executive Order review is contained 
in the accompanying Regulatory Impact Analysis, which can be found in 
the docket for this action.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action meets the criteria set forth in 5 U.S.C. 
804(2).

List of Subjects

40 CFR Part 9

    Environmental protection, Reporting and recordkeeping requirements.

40 CFR Part 257

    Environmental protection, Beneficial use, Coal combustion products, 
Coal combustion residuals, Coal combustion waste, Disposal, Hazardous 
waste, Landfill, Surface impoundment.

Michael S. Regan,
Administrator.

    For the reasons set out in the preamble, title 40, chapter I, of 
the Code of Federal Regulations is amended as follows:

PART 9--OMB APPROVALS UNDER THE PAPERWORK REDUCTION ACT

0
 1. The authority citation for part 9 continues to read as follows:

    Authority: 7 U.S.C. 135 et seq., 136-136y; 15 U.S.C. 2001, 2003, 
2005, 2006, 2601-2671; 21 U.S.C. 331j, 346a, 31 U.S.C. 9701; 33 
U.S.C. 1251 et seq., 1311, 1313d, 1314, 1318, 1321, 1326, 1330, 
1342, 1344, 1345 (d) and (e), 1361; E.O. 11735, 38 FR 21243, 3 CFR, 
1971-1975 Comp. p. 973; 42 U.S.C. 241, 242b, 243, 246, 300f, 300g, 
300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-1, 300j-2, 
300j-3, 300j-4, 300j-9, 1857 et seq., 6901-6992k, 7401-7671q, 7542, 
9601-9657, 11023, 11048.


0
2. Amend Sec.  9.1 by adding an undesignated center heading and an 
entry for ``257.50-257.107'' in numerical order to read as follows:


Sec.  9.1   OMB approvals under the Paperwork Reduction Act

* * * * *

------------------------------------------------------------------------
                                                            OMB control
                     40 CFR citation                            No.
------------------------------------------------------------------------
 
                                * * * * *
------------------------------------------------------------------------
      Disposal of Coal Combustion Residuals From Electric Utilities
------------------------------------------------------------------------
257.50-257.107..........................................       2050-0223
 
                                * * * * *
------------------------------------------------------------------------

* * * * *

PART 257--CRITERIA FOR CLASSIFICATION OF SOLID WASTE DISPOSAL 
FACILITIES AND PRACTICES

0
3. The authority citation for part 257 is revised to read as follows:

    Authority: 42 U.S.C. 6907(a)(3), 6912(a)(1), 6927, 6944, 6945(a) 
and (d); 33 U.S.C. 1345(d) and (e).

Subpart A [Amended]

0
4. Amend Sec.  257.1 by revising paragraph (c)(12) to read as follows:


Sec.  257.1  Scope and purpose.

* * * * *
    (c) * * *
    (12) Except as otherwise specifically provided in subpart D of this 
part, the criteria in subpart A of this part do not apply to CCR units, 
as that term is defined in subpart D of this part. CCR units are 
instead subject to subpart D of this part.

Subpart D [Amended]

0
5. Amend subpart D by removing the phrase ``Web site'' and adding in 
its place the word ``website'' wherever it appears.

0
6. Amend Sec.  257.50 by revising paragraph (c), (d), and (e) to read 
as follows:


Sec.  257.50  Scope and purpose.

* * * * *
    (c) This subpart also applies to inactive CCR surface impoundments 
at active electric utilities or independent power producers, regardless 
of how electricity is currently being produced at the facility.
    (d) (1) This subpart applies to CCR management units containing 
1,000 tons or greater of CCR, located at active facilities or 
facilities with a legacy CCR surface impoundment.
    (2) CCR management units containing greater than or equal to 1 ton 
and less than 1,000 tons of CCR, located at active facilities or 
facilities with a legacy CCR surface impoundment, are subject only to 
the requirements of the facility evaluation report in Sec.  257.75 
until a permitting authority determines that regulation of these units, 
either individually or in the aggregate, is warranted and determines 
the applicable requirements.
    (e) This subpart applies to electric utilities or independent power 
producers that ceased producing electricity prior to October 19, 2015 
and have a legacy CCR surface impoundment onsite.
* * * * *


Sec.  257.51   [Removed and Reserved]

0
7. Amend subpart D by removing and reserving Sec.  257.51.

0
8. Revise Sec.  257.52 to read as follows:


Sec.  257.52  Applicability of other regulations.

    (a) Compliance with the requirements of this subpart does not 
affect the need for the owner or operator of a CCR unit to comply with 
all other applicable federal, state, tribal, or local laws or other 
requirements.
    (b) Any CCR unit continues to be subject to the requirements in 
Sec. Sec.  257.3-1, 257.3-2, and 257.3-3.

0
9. Amend Sec.  257.53 by:
0
a. Revising the definition of ``Active facility or active electric 
utilities or independent power producers'';

[[Page 39100]]

0
b. Adding in alphabetical order the definition of ``Closed prior to 
October 19, 2015'';
0
c. Revising the definition of ``CCR landfill or landfill'';
0
d. Adding in alphabetical order the definition of ``CCR management 
unit'';
0
e. Revising the definitions of ``CCR surface impoundment or 
impoundment'' and ``CCR unit'';
0
f. Adding in alphabetical order the definitions of ``Critical 
infrastructure'', ``Contains both CCR and liquids'' and ``Inactive CCR 
landfill'';
0
g. Revising the definition of ``Inactive CCR surface impoundment'';
0
h. Adding in alphabetical order the definitions of ``Inactive facility 
or inactive electric utility or independent power producer'', 
``Infiltration'', ``Legacy CCR surface impoundment'', and ``Liquids'';
0
i. Revising the definitions of ``Operator'' and ``Owner'';
0
j. Adding in alphabetical order the definition of ``Regulated CCR 
unit'';
0
k. Revising the definition of ``State Director'';
0
l. Removing the definitions of ``Technically feasible'' and 
``Technically infeasible''; and
0
m. Adding in alphabetical order the definitions of ``Technically 
feasible or feasible'' and ``Technically infeasible or infeasible''.
    The revisions and additions read as follows:


Sec.  257.53  Definitions.

* * * * *
    Active facility or active electric utilities or independent power 
producers means any facility subject to the requirements of this 
subpart that is in operation on or after October 19, 2015. An electric 
utility or independent power producer is in operation if it is 
generating electricity that is provided to electric power transmission 
systems or to electric power distribution systems on or after October 
19, 2015. An off-site disposal facility is in operation if it is 
accepting or managing CCR on or after October 19, 2015.
* * * * *
    Closed prior to October 19, 2015 means the CCR landfill or surface 
impoundment completed closure of the unit in accordance with state law 
prior to October 19, 2015.
* * * * *
    CCR landfill or landfill means an area of land or an excavation 
that contains CCR and which is not a surface impoundment, an 
underground injection well, a salt dome formation, a salt bed 
formation, an underground or surface coal mine, or a cave. For purposes 
of this subpart, a CCR landfill also includes sand and gravel pits and 
quarries that receive CCR, CCR piles, and any practice that does not 
meet the definition of a beneficial use of CCR.
    CCR management unit means any area of land on which any 
noncontainerized accumulation of CCR is received, is placed, or is 
otherwise managed, that is not a regulated CCR unit. This includes 
inactive CCR landfills and CCR units that closed prior to October 19, 
2015, but does not include roadbed and associated embankments in which 
CCR is used unless the facility or a permitting authority determines 
that the roadbed is causing or contributing to a statistically 
significant level above the groundwater protection standard established 
under Sec.  257.95(h).
* * * * *
    CCR surface impoundment or impoundment means a natural topographic 
depression, man-made excavation, or diked area, designed to hold an 
accumulation of CCR and liquids, and the unit treats, stores, or 
disposes of CCR.
    CCR unit means any CCR landfill, CCR surface impoundment, or 
lateral expansion of a CCR landfill or CCR surface impoundment, or a 
combination of more than one of these units, based on the context of 
the paragraph(s) in which it is used. This term includes both new and 
existing units, unless otherwise specified. This term includes CCR 
management units and legacy CCR surface impoundments.
    Contains both CCR and liquids means that both CCR and liquids are 
present in a CCR surface impoundment, except where the owner or 
operator demonstrates that the standard in Sec.  257.102(d)(2)(i) has 
been met.
    Critical infrastructure means physical structures, such as 
buildings, railways, bridges, or tunnels, that are not readily replaced 
or relocated and are either:
    (1) Necessary for the continued generation of power, or
    (2) Vital to the success or continuation of other on-going site 
activity for the public welfare. Examples of critical infrastructure 
include high power electric transmission towers, air pollution control 
or wastewater treatment systems, active CCR units, buildings, or an 
electrical substation. Buildings or other structures that exclusively 
provide commercial or financial benefit to private entities are not 
critical infrastructure.
* * * * *
    Inactive CCR landfill means an area of land or an excavation that 
contains CCR but that no longer receives CCR on or after October 19, 
2015 and that is not a surface impoundment, an underground injection 
well, a salt dome formation, a salt bed formation, an underground or 
surface coal mine, or a cave. This term also includes sand and gravel 
pits that contain CCR and CCR piles, which have not received CCR on or 
after October 19, 2015, and abandoned or inactive CCR piles.
    Inactive CCR surface impoundment means a CCR surface impoundment 
located at an active facility that no longer receives CCR on or after 
October 19, 2015, and still contains both CCR and liquids on or after 
October 19, 2015.
    Inactive facility or inactive electric utility or independent power 
producer means any electric utility or independent power producer that 
ceased providing power to electric power transmission systems or to 
electric power distribution systems before October 19, 2015. An off-
site disposal facility is inactive if it ceased accepting or managing 
CCR prior to October 19, 2015.
* * * * *
    Infiltration means the migration or movement of liquid, such as 
surface water or ground water, into or through a CCR unit from any 
direction, including from the surface, laterally, and through the 
bottom of the unit.
* * * * *
    Legacy CCR surface impoundment means a CCR surface impoundment that 
no longer receives CCR but contained both CCR and liquids on or after 
October 19, 2015, and that is located at an inactive electric utility 
or independent power producer.
* * * * *
    Liquids means any fluid (such as water) that has no independent 
shape but has a definite volume and does not expand indefinitely and 
that is only slightly compressible. This encompasses all of the various 
types of liquids that may be present in a CCR unit, including water 
that was sluiced into an impoundment along with CCR, precipitation, 
surface water, groundwater, and any other form of water that has 
migrated into the impoundment, which may be found as free water or 
standing water ponded above CCR or porewater intermingled with CCR.
* * * * *
    Operator means the person(s) responsible for the overall operation 
of a CCR unit. This term includes those person(s) or parties 
responsible for disposal or otherwise actively engaged in the solid 
waste management of CCR. It also includes those responsible for 
directing or overseeing groundwater

[[Page 39101]]

monitoring, closure or post-closure activities at a CCR unit.
* * * * *
    Owner means the person(s) who owns a CCR unit or part of a CCR 
unit, or a facility, whether in full or in part.
* * * * *
    Regulated CCR unit means any new CCR landfill, existing CCR 
landfill, new CCR surface impoundment, existing CCR surface 
impoundment, inactive CCR surface impoundment, or legacy CCR surface 
impoundment. This term does not include CCR management units.
* * * * *
    State Director means the chief administrative officer of the lead 
state agency responsible for implementing the state program regulating 
disposal in CCR units.
* * * * *
    Technically feasible or feasible means possible to do in a way that 
would likely be successful.
    Technically infeasible or infeasible means not possible to do in a 
way that would likely be successful.
* * * * *

0
10. Amend Sec.  257.61 by revising the introductory text of paragraph 
(a) to read as follows:


Sec.  257.61  Wetlands.

    (a) New CCR landfills, existing and new CCR surface impoundments, 
and all lateral expansions of CCR units must not be located in 
wetlands, as defined in Sec.  230.41(a) of this chapter, unless the 
owner or operator demonstrates by the dates specified in paragraph (c) 
of this section that the CCR unit meets the requirements of paragraphs 
(a)(1) through (5) of this section.
* * * * *

0
11. Amend Sec.  257.73 by revising the introductory text of paragraph 
(a) to read as follows:


Sec.  257.73  Structural integrity criteria for existing CCR surface 
impoundments.

    (a) The requirements of paragraphs (a)(1) through (4) of this 
section apply to all existing CCR surface impoundments and legacy CCR 
surface impoundments, except for those that are incised CCR surface 
impoundments.
* * * * *

0
12. Add Sec.  257.75 to read as follows:


Sec.  257.75  Requirements for identifying CCR management units.

    (a) Applicability. The requirements of this section apply to owners 
and operators of active facilities or facilities with a legacy CCR 
surface impoundment.
    (b) Facility evaluation. The owner or operator of an active 
facility or a facility with a legacy CCR surface impoundment must 
conduct a facility evaluation to identify all CCR management units at 
the facility in accordance with paragraphs (c) through (e) of this 
section. At a minimum, the presence or absence of CCR management units 
at the facility must be confirmed and documented through a thorough 
evaluation of reasonably and readily available records that contain the 
information needed to prepare the Facility Evaluation Reports Part 1 
and Part 2 required by paragraphs (c) and (d) of this section. The 
facility evaluation must also include a physical inspection of the 
facility. Where necessary, the physical inspection must include field 
investigation activities to fill data gaps, such as conducting 
exploratory soil borings, geophysical assessments, or any other similar 
physical investigation activities to establish the location and 
boundaries of potential or likely CCR management units, and to 
affirmatively rule out other areas of potential CCR placement at the 
facility that were identified during the information review or physical 
inspection. The facility evaluation must identify all CCR management 
units at the facility regardless of when the CCR management unit came 
into existence.
    (c) Facility Evaluation Report Part 1. (1) No later than Monday, 
February 9, 2026, the owner or operator of an active facility or a 
facility with a legacy CCR surface impoundment must prepare a Facility 
Evaluation Report Part 1, which shall contain, to the extent reasonably 
and readily available, the information specified in paragraphs 
(c)(1)(i) through (xiv) of this section. The owner or operator has 
prepared the Facility Evaluation Report Part 1 when the report has been 
placed in the facility's operating record as required by Sec.  
257.105(f)(25).
    (i) The name and address of the person(s) owning and operating the 
facility; the unit name associated with each regulated CCR unit and CCR 
management unit at the facility; and the identification number of each 
regulated CCR unit and CCR management unit if any have been assigned by 
the state or by the owner.
    (ii) The location of any CCR management unit identified on the most 
recent U.S. Geological Survey (USGS) 7\1/2\ minute or 15-minute 
topographic quadrangle map, or a topographic map of equivalent scale if 
a USGS map is not available. The location of each regulated CCR unit at 
the facility must also be identified in the same manner.
    (iii) A statement of the purpose(s) for which each CCR management 
unit at the facility is or was used.
    (iv) A description of the physical and engineering properties of 
the foundation and abutment materials on which each CCR management unit 
is constructed.
    (v) A discussion of any known spills or releases of CCR, including 
any associated remediation activities, from each CCR management unit 
and whether the spills or releases were reported to state or federal 
agencies.
    (vi) Any record or knowledge of structural instability of each CCR 
management unit.
    (vii) Any record or knowledge of groundwater contamination 
associated or potentially associated with each CCR management unit.
    (viii) The size of each CCR management unit, including the general 
lateral and vertical dimensions and an estimate of the volume of waste 
contained within the unit.
    (ix) Dates when each CCR management unit first received CCR and 
when each CCR management unit ceased receiving CCR.
    (x) Identification of all types of CCR in each CCR management unit 
at the facility.
    (xi) A narrative description of any closure activities that have 
occurred, including any applicable engineering drawings or reports.
    (xii) A narrative that documents the data reviewed as part of the 
facility evaluation process, and that lists all data and information 
indicating the presence or absence of CCR management units at the 
facility.
    (xiii) Any supporting information used to identify and evaluate CCR 
management units at the facility, including but not limited to any 
construction diagrams, engineering drawings, permit documents, 
wastestream flow diagrams, aerial photographs, satellite images, 
historical facility maps, any field or analytical data, groundwater 
monitoring data or reports, inspection reports, documentation of 
interviews with current or former facility workers, and other documents 
used to identify and evaluate CCR management units at the facility.
    (xiv) A narrative description of any data gaps for information in 
paragraphs (c)(i) through (xiii) of this section, not available in 
existing information collection records and a plan for remedying 
identified data gaps through a physical examination of the facility, 
including any field or laboratory work needed to remedy data gaps in 
the Facility Evaluation Report Part 1 record. The plan must include the 
major

[[Page 39102]]

milestones needed to fill the identified data gaps (e.g., a physical 
examination of the facility, sampling of media, measurements of CCR 
concentrations in and around the unit or physical presence, delineation 
of CCR management unit(s)) and dates to complete such needed tasks. 
Also, as necessary and timely, any updates to data gap remedy plans 
must be added to the public record during the Facility Evaluation 
Report Part 1.
    (2) The owner or operator of any facility regulated under this 
subpart must obtain a certification from a qualified professional 
engineer stating that the Facility Evaluation Report Part 1 meets the 
requirements of paragraph (c)(1) of this section.
    (3) The owner or operator of any facility regulated under this 
subpart must certify the Facility Evaluation Report Part 1 required by 
paragraph (c)(1) of this section with the following statement signed by 
the owner or operator or an authorized representative:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (4) No later than Monday, February 9, 2026, the owner or operator 
must notify the Agency of the establishment of a CCR website using the 
procedures in Sec.  257.107(a) via the ``contact us'' form on EPA's CCR 
website.
    (5) The owner or operator of any facility regulated under this 
subpart that does not contain any CCR management unit must submit 
Facility Evaluation Report Part 1 documenting the steps taken during 
the facility evaluation to determine the absence of any CCR management 
unit. The Facility Evaluation Report Part 1 must include the 
certifications required under paragraph (c)(3) of this section.
    (d) Facility evaluation report part 2. (1) No later than Monday, 
February 8, 2027, the owner or operator of an active facility or a 
facility with a legacy CCR surface impoundment must prepare a facility 
evaluation report part 2, which shall contain, to the extent not 
provided in the Facility Evaluation Report Part 1 under paragraph (c) 
of this section, the information specified in paragraphs (d)(1)(i) 
through (xiii) of this section obtained from a physical evaluation of 
the facility, including where necessary field sampling. The owner or 
operator has prepared the facility evaluation report part 2 when the 
report has been placed in the facility's operating record as required 
by Sec.  257.105(f)(26).
    (i) The name and address of the person(s) owning and operating the 
facility; the unit name associated with each regulated CCR unit and CCR 
management unit at the facility; and the identification number of each 
regulated CCR unit and CCR management unit if any have been assigned by 
the state or by the owner.
    (ii) The location of any CCR management unit identified on the most 
recent U.S. Geological Survey (USGS) 7\1/2\ minute or 15-minute 
topographic quadrangle map, or a topographic map of equivalent scale if 
a USGS map is not available. The location of each regulated CCR unit at 
the facility must also be identified in the same manner.
    (iii) A statement of the purpose(s) for which each CCR management 
unit at the facility is or was used.
    (iv) A description of the physical and engineering properties of 
the foundation and abutment materials on which each CCR management unit 
was constructed.
    (v) Any further evidence of known spills or releases, including any 
associated remediation activities, of CCR from each CCR management unit 
and whether the spills or releases were reported to state or federal 
agencies.
    (vi) Any further evidence of structural instability of each CCR 
management unit.
    (vii) Any further evidence of groundwater contamination associated 
or potentially associated with each CCR management unit.
    (viii) The size of each CCR management unit, including the general 
lateral and vertical dimensions and an estimate of the volume of CCR 
contained within the unit.
    (ix) Identification of the types of CCR in each CCR management 
unit.
    (x) A narrative description of any closure activities that have 
occurred, including any applicable engineering drawings or reports.
    (xi) A narrative that documents the nature and extent of field 
oversight activities and data reviewed as part of the facility 
evaluation process, and that lists all data and information that was 
reviewed indicating the presence or absence of CCR management units at 
the facility.
    (xii) Any additional supporting information used to identify and 
evaluate CCR management units at the facility, including but not 
limited to any construction diagrams, engineering drawings, permit 
documents, wastestream flow diagrams, aerial photographs, satellite 
images, historical facility maps, any field or analytical data, 
groundwater monitoring data or reports, inspection reports, and other 
documents used to identify and assess CCR management units at the 
facility. Additionally, as necessary and timely, any updates to the 
part 1 data gap remedy plan must be added to the record during the 
facility evaluation report part 2 timeframe.
    (xiii) The Facility Evaluation Report Part 2 must explain how each 
data gap identified in Facility Evaluation Report Part 1 was addressed.
    (xiv) A description of each CCR management unit for which 
regulation under this subpart is deferred for allowable reasons as 
specified in Sec.  257.101(g) or (h). The owner or operator must 
provide documentation in the Facility Evaluation Report Part 2 to 
substantiate that the requirements Sec.  257.101(g) or (h) have been 
met.
    (2) The owner or operator of any facility regulated under this 
subpart must obtain a certification from a qualified professional 
engineer stating that the Facility Evaluation Report Part 2 meets the 
requirements of paragraph (d)(1) of this section.
    (3) The owner or operator of any facility regulated under this 
subpart must certify the Facility Evaluation Report Part 2 required by 
paragraph (d)(1) of this section with the following statement signed by 
the owner or operator or an authorized representative:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (4) The owner or operator of any facility regulated under this 
subpart that does not contain any CCR management unit must submit 
Facility Evaluation Report Part 2 documenting the steps taken during 
the facility evaluation to determine the absence of any CCR management 
unit. The Facility Evaluation Report Part 2 must include the 
certifications required under paragraph (d)(3) of this section.
    (e) The owner or operator of the facility must comply with the 
recordkeeping requirements specified in Sec.  257.105(f), the 
notification requirements specified in Sec.  257.106(f), and the 
internet requirements specified in Sec.  257.107(f).

[[Page 39103]]


0
13. Amend Sec.  257.80 by revising paragraphs (a) and (b)(6) to read as 
follows:


Sec.  257.80  Air criteria.

    (a) The owner or operator of a CCR unit must adopt measures that 
will effectively minimize CCR from becoming airborne at the facility, 
including CCR fugitive dust originating from CCR units, roads, and 
other CCR management and material handling activities.
    (b) * * *
    (6) Amendment of the plan. The owner or operator subject to the 
requirements of this section may amend the written CCR fugitive dust 
control plan at any time provided the revised plan is placed in the 
facility's operating record as required by Sec.  257.105(g)(1). The 
owner or operator must amend the written plan no later than 30 days 
whenever there is a change in conditions that would substantially 
affect the written plan in effect, such as the construction and 
operation of a new CCR unit.
* * * * *

0
14. Amend Sec.  257.82 by revising the introductory text of paragraph 
(a) to read as follows:


Sec.  257.82  Hydrologic and hydraulic capacity requirements for CCR 
surface impoundments.

    (a) The owner or operator of an existing or new CCR surface 
impoundment, legacy CCR surface impoundment, or any lateral expansion 
of a CCR surface impoundment must design, construct, operate, and 
maintain an inflow design flood control system as specified in 
paragraphs (a)(1) and (2) of this section.
* * * * *

0
15. Amend Sec.  257.83 by revising the introductory text of paragraphs 
(a)(1) and (b)(1) to read as follows:


Sec.  257.83  Inspection requirements for CCR surface impoundments.

    (a) * * *
    (1) All CCR surface impoundments, including legacy CCR surface 
impoundments, and any lateral expansion of a CCR surface impoundment 
must be examined by a qualified person as follows:
* * * * *
    (b) * * *
    (1) If the existing or new CCR surface impoundment or any lateral 
expansion of the CCR surface impoundment or legacy CCR surface 
impoundments is subject to the periodic structural stability assessment 
requirements under Sec.  257.73(d) or Sec.  257.74(d), the CCR unit 
must additionally be inspected on a periodic basis by a qualified 
professional engineer to ensure that the design, construction, 
operation, and maintenance of the CCR unit is consistent with 
recognized and generally accepted good engineering standards. The 
inspection must, at a minimum, include:
* * * * *

0
16. Revise and republish Sec.  257.90 to read as follows:


Sec.  257.90  Applicability.

    (a) Applicability. All CCR units are subject to the groundwater 
monitoring and corrective action requirements under Sec. Sec.  257.90 
through 257.98, except as provided in paragraph (g) of this section.
    (b) Initial timeframes--(1) Existing CCR landfills and existing CCR 
surface impoundments. No later than October 17, 2017, the owner or 
operator of the CCR unit must be in compliance with the following 
groundwater monitoring requirements:
    (i) Install the groundwater monitoring system as required by Sec.  
257.91;
    (ii) Develop the groundwater sampling and analysis program to 
include selection of the statistical procedures to be used for 
evaluating groundwater monitoring data as required by Sec.  257.93;
    (iii) Initiate the detection monitoring program to include 
obtaining a minimum of eight independent samples for each background 
and downgradient well as required by Sec.  257.94(b); and
    (iv) Begin evaluating the groundwater monitoring data for 
statistically significant increases over background levels for the 
constituents listed in appendix III of this part as required by Sec.  
257.94.
    (2) New CCR landfills, new CCR surface impoundments, and all 
lateral expansions of CCR units. Prior to initial receipt of CCR by the 
CCR unit, the owner or operator must be in compliance with the 
groundwater monitoring requirements specified in paragraph (b)(1)(i) 
and (ii) of this section. In addition, the owner or operator of the CCR 
unit must initiate the detection monitoring program to include 
obtaining a minimum of eight independent samples for each background 
well as required by Sec.  257.94(b).
    (3) CCR management units. No later than Monday, May 8, 2028, the 
owner or operator of the CCR management unit must be in compliance with 
the following groundwater monitoring requirements:
    (i) Install the groundwater monitoring system as required by Sec.  
257.91.
    (ii) Develop the groundwater sampling and analysis program to 
include selection of the statistical procedures to be used for 
evaluating groundwater monitoring data as required by Sec.  257.93.
    (iii) Initiate the detection monitoring program to include 
obtaining a minimum of eight independent samples for each background 
and downgradient well, as required by Sec.  257.94(b).
    (iv) Begin evaluating the groundwater monitoring data for 
statistically significant increases over background levels for the 
constituents listed in appendix III of this part, as required by Sec.  
257.94.
    (v) Begin evaluating the groundwater monitoring data for 
statistically significant levels over groundwater protection standards 
for the constituents listed in appendix IV of this part as required by 
Sec.  257.95.
    (c) Requirement to conduct groundwater monitoring and corrective 
action. Once a groundwater monitoring system and groundwater monitoring 
program has been established at the CCR unit as required by this 
subpart, the owner or operator must conduct groundwater monitoring and, 
if necessary, corrective action throughout the active life and post-
closure care period of the CCR unit.
    (d) Responding to a release from a CCR unit. In the event of a 
release from a CCR unit, the owner or operator must immediately take 
all necessary measures to control the source(s) of releases so as to 
reduce or eliminate, to the maximum extent feasible, further releases 
of contaminants into the environment. The owner or operator of the CCR 
unit must comply with all applicable requirements in Sec. Sec.  257.96, 
257.97, and 257.98.
    (e) Annual groundwater monitoring and corrective action report. For 
existing CCR landfills and existing CCR surface impoundments, no later 
than January 31, 2018, and annually thereafter, the owner or operator 
must prepare an annual groundwater monitoring and corrective action 
report. For new CCR landfills, new CCR surface impoundments, and all 
lateral expansions of CCR units, the owner or operator must prepare the 
initial annual groundwater monitoring and corrective action report no 
later than January 31 of the year following the calendar year a 
groundwater monitoring system has been established for such CCR unit as 
required by this subpart, and annually thereafter. For CCR management 
units, the owner or operator must prepare the initial annual 
groundwater monitoring and corrective action report no later than 
January 31, 2029, and annually thereafter. For the preceding calendar

[[Page 39104]]

year, the annual report must document the status of the groundwater 
monitoring and corrective action program for the CCR unit, summarize 
key actions completed, describe any problems encountered, discuss 
actions to resolve the problems, and project key activities for the 
upcoming year. For purposes of this section, the owner or operator has 
prepared the annual report when the report is placed in the facility's 
operating record as required by Sec.  257.105(h)(1). At a minimum, the 
annual groundwater monitoring and corrective action report must contain 
the following information, to the extent available:
    (1) A map, aerial image, or diagram showing the CCR unit and all 
background (or upgradient) and downgradient monitoring wells, to 
include the well identification numbers, that are part of the 
groundwater monitoring program for the CCR unit;
    (2) Identification of any monitoring wells that were installed or 
decommissioned during the preceding year, along with a narrative 
description of why those actions were taken;
    (3) In addition to all the monitoring data obtained under 
Sec. Sec.  257.90 through 257.98, a summary including the number of 
groundwater samples that were collected for analysis for each 
background and downgradient well, the dates the samples were collected, 
and whether the sample was required by the detection monitoring or 
assessment monitoring programs;
    (4) A narrative discussion of any transition between monitoring 
programs (e.g., the date and circumstances for transitioning from 
detection monitoring to assessment monitoring in addition to 
identifying the constituent(s) detected at a statistically significant 
increase over background levels); and
    (5) Other information required to be included in the annual report 
as specified in Sec. Sec.  257.90 through 257.98.
    (6) A section at the beginning of the annual report that provides 
an overview of the current status of groundwater monitoring and 
corrective action programs for the CCR unit. At a minimum, the summary 
must specify all of the following:
    (i) At the start of the current annual reporting period, whether 
the CCR unit was operating under the detection monitoring program in 
Sec.  257.94 or the assessment monitoring program in Sec.  257.95;
    (ii) At the end of the current annual reporting period, whether the 
CCR unit was operating under the detection monitoring program in Sec.  
257.94 or the assessment monitoring program in Sec.  257.95;
    (iii) If it was determined that there was a statistically 
significant increase over background for one or more constituents 
listed in appendix III to this part pursuant to Sec.  257.94(e):
    (A) Identify those constituents listed in appendix III to this part 
and the names of the monitoring wells associated with such an increase; 
and
    (B) Provide the date when the assessment monitoring program was 
initiated for the CCR unit.
    (iv) If it was determined that there was a statistically 
significant level above the groundwater protection standard for one or 
more constituents listed in appendix IV to this part pursuant to Sec.  
257.95(g) include all of the following:
    (A) Identify those constituents listed in appendix IV to this part 
and the names of the monitoring wells associated with such an increase;
    (B) Provide the date when the assessment of corrective measures was 
initiated for the CCR unit;
    (C) Provide the date when the public meeting was held for the 
assessment of corrective measures for the CCR unit; and
    (D) Provide the date when the assessment of corrective measures was 
completed for the CCR unit.
    (v) Whether a remedy was selected pursuant to Sec.  257.97 during 
the current annual reporting period, and if so, the date of remedy 
selection; and
    (vi) Whether remedial activities were initiated or are ongoing 
pursuant to Sec.  257.98 during the current annual reporting period.
    (f) Recordkeeping, notification, and internet requirements. The 
owner or operator of the CCR unit must comply with the recordkeeping 
requirements specified in Sec.  257.105(h), the notification 
requirements specified in Sec.  257.106(h), and the internet 
requirements specified in Sec.  257.107(h).
    (g) Suspension of groundwater monitoring requirements.(1) The 
Participating State Director or EPA where EPA is the permitting 
authority may suspend the groundwater monitoring requirements under 
Sec. Sec.  257.90 through 257.95 for a CCR unit for a period of up to 
ten years, if the owner or operator provides written documentation 
that, based on the characteristics of the site in which the CCR unit is 
located, there is no potential for migration of any of the constituents 
listed in appendices III and IV to this part from that CCR unit to the 
uppermost aquifer during the active life of the CCR unit and the post-
closure care period. This demonstration must be certified by a 
qualified professional engineer and approved by the Participating State 
Director or EPA where EPA is the permitting authority, and must be 
based upon:
    (i) Site-specific field collected measurements, sampling, and 
analysis of physical, chemical, and biological processes affecting 
contaminant fate and transport, including at a minimum, the information 
necessary to evaluate or interpret the effects of the following 
properties or processes on contaminant fate and transport:
    (A) Aquifer Characteristics, including hydraulic conductivity, 
hydraulic gradient, effective porosity, aquifer thickness, degree of 
saturation, stratigraphy, degree of fracturing and secondary porosity 
of soils and bedrock, aquifer heterogeneity, groundwater discharge, and 
groundwater recharge areas;
    (B) Waste Characteristics, including quantity, type, and origin;
    (C) Climatic Conditions, including annual precipitation, leachate 
generation estimates, and effects on leachate quality;
    (D) Leachate Characteristics, including leachate composition, 
solubility, density, the presence of immiscible constituents, Eh, and 
pH; and
    (E) Engineered Controls, including liners, cover systems, and 
aquifer controls (e.g., lowering the water table). These must be 
evaluated under design and failure conditions to estimate their long-
term residual performance.
    (ii) Contaminant fate and transport predictions that maximize 
contaminant migration and consider impacts on human health and the 
environment.
    (2) The owner or operator of the CCR unit may renew this suspension 
for additional ten year periods by submitting written documentation 
that the site characteristics continue to ensure there will be no 
potential for migration of any of the constituents listed in Appendices 
III and IV of this part. The documentation must include, at a minimum, 
the information specified in paragraphs (g)(1)(i) and (ii) of this 
section and a certification by a qualified professional engineer and 
approved by the State Director or EPA where EPA is the permitting 
authority. The owner or operator must submit the documentation 
supporting their renewal request for the state's or EPA's review and 
approval of their extension one year before the groundwater monitoring 
suspension is due to expire. If the existing groundwater monitoring 
extension expires or is not approved, the owner or operator must begin 
groundwater monitoring according to paragraph (a) of this section 
within 90 days. The owner or operator may continue to renew the 
suspension for

[[Page 39105]]

ten-year periods, provided the owner or operator demonstrate that the 
standard in paragraph (g)(1) of this section continues to be met for 
the unit. The owner or operator must place each completed demonstration 
in the facility's operating record.
    (3) The owner or operator of the CCR unit must include in the 
annual groundwater monitoring and corrective action report required by 
Sec.  257.90(e) or Sec.  257.100(e)(5)(ii) any approved no migration 
demonstration.

0
17. Amend Sec.  257.95 by revising paragraph (b) to read as follows:


Sec.  257.95  Assessment monitoring program.

* * * * *
    (b) (1) Within 90 days of triggering an assessment monitoring 
program, and annually thereafter:
    (i) Except as provided by paragraph (b)(1)(ii) of this section, the 
owner or operator of the CCR unit must sample and analyze the 
groundwater for all constituents listed in appendix IV to this part.
    (ii) The owner or operator of a CCR management unit must sample and 
analyze the groundwater for all constituents listed in appendix IV to 
this part no later than Monday, May 8, 2028.
    (2) The number of samples collected and analyzed for each well 
during each sampling event must be consistent with Sec.  257.93(e), and 
must account for any unique characteristics of the site, but must be at 
least one sample from each well.
* * * * *

0
18. Revise and republish Sec.  257.100 to read as follows:


Sec.  257.100  Inactive CCR surface impoundments and Legacy CCR surface 
impoundments.

    (a) General. (1) Inactive CCR surface impoundments are subject to 
all of the requirements of this subpart applicable to existing CCR 
surface impoundments, except that an active electric utility or 
independent power producer that generates electricity without the use 
of fuel is subject to the compliance deadlines applicable to legacy CCR 
surface impoundments, provided the facility has not generated 
electricity using fuels on or after October 19, 2015.
    (2) Legacy CCR surface impoundments are subject to all of the 
requirements of this subpart applicable to existing CCR surface 
impoundments, except for the requirements in Sec. Sec.  257.60 through 
257.64 and 257.71.(b) through (d) [Reserved]
    (e) Timeframes for certain inactive CCR surface impoundments. (1) 
An inactive CCR surface impoundment for which the owner or operator has 
completed the actions by the deadlines specified in paragraphs 
(e)(1)(i) through (iii) of this section is eligible for the alternative 
timeframes specified in paragraphs (e)(2) through (6) of this section. 
The owner or operator of the CCR unit must comply with the applicable 
recordkeeping, notification, and internet requirements associated with 
these provisions. For the inactive CCR surface impoundment:
    (i) The owner or operator must have prepared and placed in the 
facility's operating record by December 17, 2015, a notification of 
intent to initiate closure of the inactive CCR surface impoundment 
pursuant to Sec.  257.105(i)(1);
    (ii) The owner or operator must have provided notification to the 
State Director and/or appropriate Tribal authority by January 19, 2016, 
of the intent to initiate closure of the inactive CCR surface 
impoundment pursuant to Sec.  257.106(i)(1); and
    (iii) The owner or operator must have placed on its CCR website by 
January 19, 2016, the notification of intent to initiate closure of the 
inactive CCR surface impoundment pursuant to Sec.  257.107(i)(1).
    (2) Location restrictions. (i) No later than April 16, 2020, the 
owner or operator of the inactive CCR surface impoundment must:
    (A) Complete the demonstration for placement above the uppermost 
aquifer as set forth by Sec.  257.60(a), (b), and (c)(3);
    (B) Complete the demonstration for wetlands as set forth by Sec.  
257.61(a), (b), and (c)(3);
    (C) Complete the demonstration for fault areas as set forth by 
Sec.  257.62(a), (b), and (c)(3);
    (D) Complete the demonstration for seismic impact zones as set 
forth by Sec.  257.63(a), (b), and (c)(3); and
    (E) Complete the demonstration for unstable areas as set forth by 
Sec.  257.64(a), (b), (c), and (d)(3).
    (ii) An owner or operator of an inactive CCR surface impoundment 
who fails to demonstrate compliance with the requirements of paragraph 
(e)(2)(i) of this section is subject to the closure requirements of 
Sec.  257.101(b)(1).
    (3) Design criteria. The owner or operator of the inactive CCR 
surface impoundment must:
    (i) No later than April 17, 2018, complete the documentation of 
liner type as set forth by Sec.  257.71(a) and (b).
    (ii) No later than June 16, 2017, place on or immediately adjacent 
to the CCR unit the permanent identification marker as set forth by 
Sec.  257.73(a)(1).
    (iii) No later than October 16, 2018, prepare and maintain an 
Emergency Action Plan as set forth by Sec.  257.73(a)(3).
    (iv) No later than April 17, 2018, compile a history of 
construction as set forth by Sec.  257.73(b) and (c).
    (v) No later than April 17, 2018, complete the initial hazard 
potential classification, structural stability, and safety factor 
assessments as set forth by Sec.  257.73(a)(2), (b), (d), (e), and (f).
    (4) Operating criteria. The owner or operator of the inactive CCR 
surface impoundment must:
    (i) No later than April 18, 2017, prepare the initial CCR fugitive 
dust control plan as set forth in Sec.  257.80(b).
    (ii) No later than April 17, 2018, prepare the initial inflow 
design flood control system plan as set forth in Sec.  257.82(c).
    (iii) No later than April 18, 2017, initiate the inspections by a 
qualified person as set forth by Sec.  257.83(a).
    (iv) No later than July 19, 2017, complete the initial annual 
inspection by a qualified professional engineer as set forth by Sec.  
257.83(b).
    (5) Groundwater monitoring and corrective action. The owner or 
operator of the inactive CCR surface impoundment must:
    (i) No later than April 17, 2019, comply with groundwater 
monitoring requirements set forth in Sec. Sec.  257.90(b) and 
257.94(b); and
    (ii) No later than August 1, 2019, prepare the initial groundwater 
monitoring and corrective action report as set forth in Sec.  
257.90(e).
    (6) Closure and post-closure care. The owner or operator of the 
inactive CCR surface impoundment must:
    (i) No later than April 17, 2018, prepare an initial written 
closure plan as set forth in Sec.  257.102(b); and
    (ii) No later than April 17, 2018, prepare an initial written post-
closure care plan as set forth in Sec.  257.104(d).
    (f) Timeframes for legacy CCR surface impoundments. Owners and 
operators of legacy CCR surface impoundments are subject to the 
requirements of paragraphs (f)(1) through (5) of this section, except 
as provided in paragraphs (g) through (i) of this section.
    (1) Legacy CCR surface impoundment applicability report. (i) Except 
as provided in paragraph (f)(1)(iii) of this section, owners and 
operators of legacy CCR surface impoundments must prepare a report for 
each legacy CCR surface impoundment no later than Friday, November 8, 
2024. The owner or operator has prepared the applicability report when 
the report has been placed in the facility's operating record as 
required by Sec.  257.105(k)(1). At a minimum, the report for each 
legacy

[[Page 39106]]

CCR surface impoundment must contain:
    (A) The name and address of the person(s) owning and operating the 
legacy CCR surface impoundment with their business phone number and 
email address.
    (B) The name associated with the legacy CCR surface impoundment.
    (C) Information to identify the legacy CCR surface impoundment, 
including a figure of the facility and where the unit is located at the 
facility, facility address, and the latitude and longitude of the 
facility.
    (D) The identification number of the legacy CCR surface impoundment 
if one has been assigned by the state. (E) A description of the current 
site conditions, including the current use of the inactive facility.
    (ii) (A) The owner or operator of any legacy CCR surface 
impoundment must certify the applicability report required by paragraph 
(f)(1)(i) of this section with the following statement signed by the 
owner or operator or an authorized representative:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (B) The owner or operator must notify the Agency of the 
establishment of the facility's CCR website and the applicability of 
the rule, using the procedures in Sec.  257.107(a) via the ``contact 
us'' form on EPA's CCR website.
    (iii) (A) Notwithstanding the deadline to complete the 
applicability report under paragraph (f)(1)(i) of this section, an 
owner or operator may secure additional time to complete the report for 
the sole reason of determining through a field investigation whether 
the unit contains both CCR and liquids. The amount of additional time 
that can be secured is limited as specified in paragraph (f)(1)(iii)(B) 
of this section. For owners and operators following the procedures of 
this paragraph (f)(1)(iii), the compliance timeframes for the 
requirements specified under paragraphs (f)(2) through (5) of this 
section are adjusted by the length of the extension(s) justified under 
this paragraph (f)(1)(iii). To qualify for additional time, the owner 
or operator must prepare an applicability extension report consisting 
of the following:
    (1) The information specified in paragraph (f)(1)(i)(A) through (C) 
of this section;
    (2) A statement by the owner or operator that to the best of their 
knowledge or belief, existing and available information does not 
provide a sufficient basis to determine that the unit contained free 
liquids on or after October 19, 2015; and
    (3) The details of a written field investigation work plan, 
including of the following:
    (i) A detailed description of the approach to characterize the 
physical, topographic, geologic, hydrogeologic, and hydraulic 
properties of the CCR in the unit and native geologic materials beneath 
and surrounding the unit, and how those properties will be used to 
investigate for the presence of free liquids in the CCR unit.
    (ii) A detailed description of the methods and tools that will be 
employed to determine whether the unit contains free liquids, the 
rationale for choosing these methods and tools, how these methods and 
tools will be implemented, and at what level of spatial resolution at 
the CCR unit to identify and monitor for the presence of free liquids.
    (iii) A detailed description of how groundwater elevations will be 
determined, and at what level of spatial resolution, in relation to the 
sides and bottom of the CCR unit and how any intersection of the 
groundwater table with the CCR unit will be evaluated, and at what 
level of spatial resolution.
    (iv) A plan for evaluating stormwater flow over the surface of the 
unit, stormwater drainage from the unit, and stormwater infiltration 
into the unit and how those processes may result in the formation of 
free liquids in the CCR unit. This plan must include a current 
topographic map showing surface water flow and any pertinent natural or 
man-made features present relevant to stormwater drainage, infiltration 
and related processes.
    (v) An estimated timeline to complete the workplan and make a 
determination if the CCR unit contains free liquids.
    (vi) A narrative discussion of how the results from implementing 
the workplan will determine whether the unit contains free liquids 
specified.
    (vii) A narrative discussion describing any anticipated problems 
that may be encountered during implementation of the workplan and what 
actions will be taken to resolve the problems, and anticipated 
timeframes necessary for such a contingency.
    (viii) The owner or operator of the CCR unit must obtain a written 
certification from a qualified professional engineer stating that the 
field investigation work plan meets the requirements of paragraph 
(f)(1)(iii)(A)(3) of this section.
    (B) The maximum amount of additional time that can be secured under 
paragraph (f)(1)(iii) of this section is 18 months, secured in 6-month 
increments, provided each 6-month increment is supported by an 
applicability extension report.
    (C) Owners and operator must prepare the initial applicability 
extension report no later than Friday, November 8, 2024. Subsequent 
applicability extension reports must be prepared no later than 6 months 
after completing the preceding applicability extension report. The 
owner or operator has prepared the applicability extension report when 
the report is placed in the facility's operating record as required by 
Sec.  257.105(k)(2).
    (D) No later than Friday, November 8, 2024, the owner or operator 
must notify the Agency of the establishment of a CCR website using the 
procedures in Sec.  257.107(a) via the ``contact us'' form on EPA's CCR 
website.
    (E) If the owner or operator determines that the unit contains free 
liquids during implementation of the written field investigation 
workplan, the owner or operator must cease operating under these 
extension provisions and prepare the applicability report required by 
paragraph (f)(1) of this section within 14 days of determining that the 
unit contains free liquids. The owner or operator must comply with the 
requirements specified under paragraphs (f)(2) through (5) of this 
section under new timeframes. The new timeframes are determined by 
adding the total length of the extension(s) justified under paragraph 
(f)(1)(iii) of this section to each of the deadlines specified under 
paragraphs (f)(2) through (5) of this section.
    (F) If the owner or operator determines that the unit does not 
contain both CCR and liquids during implementation of the written field 
investigation work plan, the owner or operator must prepare a 
notification stating that the field investigation has concluded and 
that the owner or operator has determined that the unit does not 
contain both CCR and liquids and does not meet the definition of a 
legacy CCR surface impoundment. The owner or operator has prepared the 
notification when the report is placed in the facility's operating 
record as required by Sec.  257.105(k)(3).
    (G) If the owner or operator does not complete the field 
investigation work within the timeframes specified in paragraph 
(f)(1)(iii)(B) of this section,

[[Page 39107]]

the unit shall be considered a legacy CCR surface impoundment and must 
comply with the requirements under paragraphs (f)(2) through (5) of 
this section pursuant to the timeframes specified under paragraph 
(f)(1)(iii)(E) of this section.
    (2) Design criteria. The owner or operator of a legacy CCR surface 
impoundment must:
    (i) Except for legacy CCR surface impoundments that are incised, no 
later than Wednesday, January 8, 2025, place on or immediately adjacent 
to the CCR unit the permanent identification marker as set forth by 
Sec.  257.73(a)(1).
    (ii) Except for legacy CCR surface impoundments that do not exceed 
the height and/or storage volume thresholds under Sec.  257.73(b), no 
later than Monday, February 9, 2026, compile a history of construction 
as set forth by Sec.  257.73(c).
    (iii) Except for legacy CCR surface impoundments that are incised, 
no later than Friday, May 8, 2026, complete the initial hazard 
potential classification assessment as set forth by Sec.  257.73(a)(2) 
and (f).
    (iv) Except for legacy CCR surface impoundments that do not exceed 
the height and/or storage volume thresholds under Sec.  257.73(b), no 
later than Friday, May 8, 2026, complete the structural stability and 
safety factor assessments as set forth by Sec.  257.73(d), (e), and 
(f).
    (v) Except for legacy CCR surface impoundments that are incised, no 
later than Friday, May 8, 2026, prepare and maintain an Emergency 
Action Plan as set forth by Sec.  257.73(a)(3).
    (3) Operating criteria. The owner or operator of the legacy CCR 
surface impoundment must:
    (i) No later than Friday, November 8, 2024, prepare the initial CCR 
fugitive dust control plan as set forth in Sec.  257.80(b).
    (ii) No later than Friday, November 8, 2024, prevent the unknowing 
entry, and minimize the possibility for the unauthorized entry, of 
persons or livestock onto the legacy CCR surface impoundment.
    (iii) No later than Friday, November 8, 2024, initiate the 
inspections by a qualified person as set forth by Sec.  257.83(a).
    (iv) No later than Monday, February 10, 2025, complete the initial 
annual inspection by a qualified professional engineer as set forth by 
Sec.  257.83(b).
    (v) No later than Friday, May 8, 2026, prepare the initial inflow 
design flood control system plan as set forth in Sec.  257.82(c).
    (vi) No later than Thursday, January 8, 2026, prepare the initial 
annual fugitive dust control report as set forth in Sec.  257.80(c).
    (4) Groundwater monitoring and corrective action. No later than 
Monday, May 10, 2027, the owner or operator of the legacy CCR surface 
impoundment must:
    (i) Install the groundwater monitoring system as required by Sec.  
257.91.
    (ii) Develop the groundwater sampling and analysis program, 
including the selection of the statistical procedures, that will be 
used for evaluating groundwater monitoring data as required by Sec.  
257.93.
    (iii) Be in compliance with the following groundwater monitoring 
requirements:
    (A) Initiate the detection monitoring program to include obtaining 
a minimum of eight independent samples for each background and 
downgradient well, as required by Sec.  257.94(b).
    (B) Begin evaluating the groundwater monitoring data for 
statistically significant increases over background levels for the 
constituents listed in appendix III of this part, as required by Sec.  
257.94.
    (C) Begin evaluating the groundwater monitoring data for 
statistically significant levels over groundwater protection standards 
for the constituents listed in appendix IV of this part as required by 
Sec.  257.95.
    (iv) No later than January 31, 2027, prepare the initial 
groundwater monitoring and corrective action report as set forth in 
Sec.  257.90(e).
    (5) Closure and post-closure care. Except as provided in Sec.  
257.102(g), the owner or operator of the legacy CCR surface impoundment 
must:
    (i) No later than Monday, November 8, 2027, prepare an initial 
written closure plan as set forth in Sec.  257.102(b); and
    (ii) No later than Monday, November 8, 2027, prepare an initial 
written post-closure care plan as set forth in Sec.  257.104(d).
    (g) For owners and operators of legacy CCR surface impoundments 
that completed closure of the CCR unit by removal of waste prior to 
Friday, November 8, 2024, no later than Friday, November 8, 2024, 
complete a closure certification that includes the following supporting 
information:
    (1) The type and volume of CCR and all other materials in the unit 
prior to closure;
    (2) The methods used to verify complete removal of all CCR and 
other contaminated materials from the unit, including any post-removal 
sampling and analysis;
    (3) Documentation that all CCR and other contaminated materials 
were removed from the unit, including, the results of any post-removal 
sampling and analysis that was conducted;
    (4) The methods used to verify complete decontamination of all 
areas affected by releases from the unit, including but not limited to 
post-decontamination sampling and analysis;
    (5) Documentation that all areas affected by releases from the unit 
were decontaminated and that all groundwater affected by releases has 
achieved groundwater protection standards; and
    (6) Document that groundwater monitoring concentrations do not 
exceed the groundwater protection standards established pursuant to 
Sec.  257.95(h) for constituents listed in appendix IV to this part. 
The documentation must also include a demonstration that the 
groundwater monitoring system has met all of the following:
    (i) Was capable of accurately representing background water quality 
unaffected by a CCR unit;
    (ii) Was capable of accurately representing the quality of water 
passing the waste boundary of the unit;
    (iii) Was capable of detecting contamination in the uppermost 
aquifer;
    (iv) Monitored all potential contaminant pathways;
    (v) Established groundwater background concentrations for appendix 
IV constituents and compared samples to those background 
concentrations;
    (vi) Monitoring wells must have been cased in a manner that 
maintains the integrity of the monitoring well borehole. This casing 
must have been screened or perforated and packed with gravel or sand, 
where necessary, to enable collection of groundwater samples. The 
annular space (i.e., the space between the borehole and well casing) 
above the sampling depth must have been sealed to prevent contamination 
of samples and the groundwater; and
    (vii) The last groundwater monitoring sample used to document that 
the standard in paragraph (g)(3) of this section has been met must have 
been collected no earlier than one year prior to the initiation of 
closure.
    (h) If the owner or operator of a legacy CCR surface impoundment is 
unable to complete the closure by removal certification by the date 
listed in paragraph (f)(1)(i) of this section, they may elect to 
conduct groundwater monitoring in accordance with Sec. Sec.  257.90 
through 257.95 to demonstrate there are no exceedances of the 
groundwater protection standards. If the owner or operator meets all 
the requirements of paragraph (h)(1) of this

[[Page 39108]]

section, no further requirements under this subpart apply. If the owner 
or operator does not meet the requirements of paragraph (h)(1) of this 
section by Monday, May 8, 2028 or if one or more constituents in 
appendix IV to this part are detected at statistically significant 
levels above the groundwater protection standard established under 
Sec.  257.95(h), they must proceed in accordance with paragraph (h)(2) 
of this section.
    (1) In order to comply with this paragraph (h)(1), the owner or 
operator must complete all of the following:
    (i) Prepare a notification of intent to certify closure no later 
than Friday, November 8, 2024. The owner or operator has prepared the 
notification when the report is placed in the facility's operating 
record as required by Sec.  257.105(k)(4).
    (ii) Conduct groundwater monitoring in accordance with Sec. Sec.  
257.90-257.95 for at least two consecutive sampling events to 
demonstrate that all constituents in appendix IV of this part have 
concentrations that do not exceed the groundwater protection standards 
listed in Sec.  257.95(h).
    (iii) Complete a closure by removal certification documenting 
compliance with paragraphs (g)(1) through (5) and (h)(1)(ii) of this 
section no later than Monday, May 8, 2028.
    (2) If the owner or operator does not meet the requirements of 
paragraph (h)(1) of this section (e.g., by the date or they detect an 
SSL of an appendix IV constituent), they must comply with all of the 
following:
    (i) If a statistically significant level is detected, the 
corrective action provisions and proceed in accordance with Sec.  
257.102(c)(2).
    (ii) The permanent marker requirements in Sec.  257.73(a)(1) no 
later than 8 months from the date they became subject to this 
requirement.
    (iii) The applicability report requirements of paragraph (f)(1)(i) 
of this section no later than 6 months from the date they became 
subject to this requirement.
    (iv) The facility evaluation provisions for CCR management units 
under Sec.  257.75 no later than 33 months from the date they became 
subject to this requirement.
    (v) If any CCR management unit is discovered after completing the 
facility evaluation report, the fugitive dust requirements of Sec.  
257.80(b) no later than 6 months from the date of the facility 
evaluation report.
    (vi) The groundwater monitoring requirements for CCR management 
units under Sec.  257.90(b)(3)(i) through (iv) no later than 48 months 
from the date they became subject to this requirement.
    (vii) The requirement to prepare an initial written closure plan 
for CCR management units consistent with the requirements specified in 
Sec.  257.102(b)(1) no later than 54 months from the date they became 
subject to this requirement.
    (viii) The requirement to prepare an initial post-closure plan for 
CCR management units consistent with the requirements specified in 
Sec.  257.104(d)(2)(iii) no later than 54 months from the date they 
became subject to this requirement.
    (ix) The requirement to initiate the closure of CCR management 
units in accordance with the requirements of Sec.  257.102 no later 
than 60 months from the date they became subject to this requirement.
    (i) Owners and operators of legacy CCR surface impoundments that 
completed closure of the unit in accordance with Sec.  257.102(d) or 
that meet the requirements in Sec.  257.101(g) prior to Friday, 
November 8, 2024 must only:
    (1) Prepare the applicability report as set forth by Sec.  
257.100(f)(1);
    (2) Prevent the unknowing entry, and minimize the possibility for 
the unauthorized entry, of persons or livestock onto the legacy CCR 
surface impoundment as set forth in Sec.  257.100(f)(3)(ii);
    (3) Place on or immediately adjacent to the unit the permanent 
identification marker as set forth by Sec.  257.73(a)(1);
    (4) Compile a history of construction as set forth by Sec.  
257.73(c);
    (5) Prepare the initial CCR fugitive dust control plan as set forth 
in Sec.  257.80(b);
    (6) Prepare the initial annual fugitive dust control report as set 
forth in Sec.  257.80(c);
    (7) (i) Install the groundwater monitoring system as required by 
Sec.  257.91;
    (ii) Develop the groundwater sampling and analysis program, 
including the selection of the statistical procedures, that will be 
used for evaluating groundwater monitoring data as required by Sec.  
257.93;
    (iii) Be in compliance with the following groundwater monitoring 
requirements:
    (A) Initiate the detection monitoring program to include obtaining 
a minimum of eight independent samples for each background and 
downgradient well, as required by Sec.  257.94(b);
    (B) Begin evaluating the groundwater monitoring data for 
statistically significant increases over background levels for the 
constituents listed in appendix III of this part, as required by Sec.  
257.94;
    (C) Begin evaluating the groundwater monitoring data for 
statistically significant levels over groundwater protection standards 
for the constituents listed in appendix IV of this part as required by 
Sec.  257.95;
    (8) Include in the applicability report specified in Sec.  
257.100(f)(1) information on the completed closure, along with 
supporting documentation to demonstrate that the closure meets the 
performance standards in Sec.  257.102(d) or the standards specified in 
Sec.  257.101(g);
    (9) Prepare an initial written post-closure care plan as set forth 
in Sec.  257.104(d);
    (10) Conduct post-closure care as set forth in Sec.  257.104(b); 
and
    (11) Comply with applicable recordkeeping, notification, and 
website posting requirements as set forth by Sec. Sec.  257.105 through 
257.107.
    (j) The owner or operator of the legacy CCR surface impoundment 
must comply with the recordkeeping requirements specified in Sec.  
257.105(k), the notification requirements specified in Sec.  
257.106(k), and the internet requirements specified in Sec.  
257.107(k).

0
19. Amend Sec.  257.101 by adding paragraphs (e), (f), (g) and (h) to 
read as follows:


Sec.  257.101  Closure or retrofit of CCR units.

* * * * *
    (e) Except as provided in paragraph (g) of this section, the owner 
or operator of a legacy CCR surface impoundment is subject to the 
requirements of paragraphs (e)(1) and (2) of this section.
    (1) No later than Monday, May 8, 2028, an owner or operator of a 
legacy CCR surface impoundment must initiate the closure of the legacy 
CCR surface impoundment in accordance with the requirements of Sec.  
257.102.
    (2) An owner or operator of a legacy CCR surface impoundment that 
closes in accordance with paragraph (e)(1) of this section must include 
a statement in the notification required under Sec.  257.102(g) that 
the legacy CCR surface impoundment is closing under the requirement of 
paragraph (e)(1) of this section.
    (f) Except as provided in paragraphs (g) and (h) of this section, 
the owner or operator of a CCR management unit must comply with the 
requirements of paragraphs (f)(1) and (2) of this section.
    (1) No later than Tuesday, May 8, 2029, an owner or operator of a 
CCR management unit must initiate the closure of the CCR management 
unit in accordance with the requirements of Sec.  257.102.
    (2) An owner or operator of a CCR management unit that closes in

[[Page 39109]]

accordance with paragraph (f)(1) of this section must include a 
statement in the notification required under Sec.  257.102(g) that the 
CCR management unit is closing under the requirements of paragraph 
(f)(1) of this section.
    (g) Deferral to permitting for closures conducted under 
substantially equivalent regulatory authority. Notwithstanding the 
provisions of paragraphs (e) and (f) of this section, the owner or 
operator of a CCR management unit or a legacy CCR surface impoundment 
need not demonstrate compliance with the performance standards in Sec.  
257.102(c) or (d) provided they demonstrate that the closure of the CCR 
unit met the standards specified in paragraphs (g)(1) through (g)(6) of 
this section.
    (1) The owner or operator of the CCR unit must document that a 
regulatory authority played an active role in overseeing and approving 
the closure and any necessary corrective action, pursuant to an 
enforceable requirement. This includes a State or Federal permit, an 
administrative order, or consent order issued after 2015 under CERCLA 
or by an EPA-approved RCRA State program.
    (2) The owner or operator of the CCR unit must document that the 
regulatory authority required or conducted a site-specific risk 
assessment prior to (or as part of) approving the closure and any 
necessary corrective action.
    (3) The owner or operator of the CCR unit must document that it 
installed a groundwater monitoring system and performed groundwater 
monitoring that meets all of the following:
    (i) Was capable of accurately representing background water 
quality;
    (ii) Was capable of accurately representing the quality of water 
passing the waste boundary;
    (iii) Was capable of detecting contamination in the uppermost 
aquifer; and
    (iv) Monitored all potential contaminant pathways.
    (4) Must document that the closed unit meets either:
    (i) The performance standard in Sec.  257.60; or
    (ii) The performance standard in Sec.  257.102(d)(2)(i).
    (5) The owner or operator must include the following statement, 
signed by the owner or operator or an authorized representative, in the 
facility evaluation report for CCR management units specified in Sec.  
257.75 or applicability report for legacy CCR surface impoundments 
specified in Sec.  257.100(f)(1) along with all information required by 
paragraphs (g)(1) through (4) of the section:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (6) Closure equivalency determination at permitting. The owner or 
operator must submit the following documentation to the permit 
authority.
    (i) A permit application that contains sufficient information, 
including data on contaminant levels in groundwater, to demonstrate 
that the applicable Sec.  257.102 standards have been met.
    (ii) EPA will review the information to determine whether the 
``equivalency'' of the closure has been successfully demonstrated. If 
EPA or a Participating State Director determines that the closure has 
met the appropriate part 257 closure standard, EPA or a Participating 
State Director will issue a permit to require compliance with 
applicable post-closure requirements. If EPA or a Participating State 
Director determines that the closure does not meet the part 257 
standards, the owner or operator will be required to submit a complete 
permit application and obtain a permit that contains the specific 
requirements necessary for the closed unit to achieve compliance with 
Sec.  257.102.
    (h) Deferral for CCR management units under critical 
infrastructure. Notwithstanding the provisions of paragraph (f)(1) of 
this section, the owner or operator of a CCR management unit located 
beneath critical infrastructure need not initiate closure until the 
infrastructure is no longer needed, EPA or a Participating State 
Director determines closure is necessary to ensure that there is no 
reasonable probability of adverse effects on human health or the 
environment, or the closure or decommissioning of the facility, 
whichever occurs first. Owners and operators of CCR management units 
under active disposal units must meet either:
    (1) Demonstrate that the CCR management unit complies with the 
performance standard in Sec.  257.60; or
    (2) Demonstrate that the CCR management unit complies with the 
performance standard in Sec.  257.102(d)(2)(i).

0
20. Revise and republishSec.  257.102 to read as follows:


Sec.  257.102  Criteria for conducting the closure or retrofit of CCR 
units and closure of CCR management units.

    (a) General. Closure of a CCR unit must be completed either by 
leaving the CCR in place and installing a final cover system or through 
removal of the CCR and decontamination of the CCR unit, as described in 
paragraphs (b) through (j) of this section. Retrofit of a CCR surface 
impoundment must be completed in accordance with the requirements in 
paragraph (k) of this section.
    (b) Written closure plan--(1) Content of the plan. The owner or 
operator of a CCR unit must prepare a written closure plan that 
describes the steps necessary to close the CCR unit at any point during 
the active life of the CCR unit consistent with recognized and 
generally accepted good engineering practices. The written closure plan 
must include, at a minimum, the information specified in paragraphs 
(b)(1)(i) through (vi) of this section.
    (i) A narrative description of how the CCR unit will be closed in 
accordance with this section.
    (ii) If closure of the CCR unit will be accomplished through 
removal of CCR from the CCR unit, a description of the procedures to 
remove the CCR and decontaminate the CCR unit in accordance with 
paragraph (c) of this section.
    (iii) If closure of the CCR unit will be accomplished by leaving 
CCR in place, a description of the final cover system, designed in 
accordance with paragraph (d) of this section, and the methods and 
procedures to be used to install the final cover. The closure plan must 
also discuss how the final cover system will achieve the performance 
standards specified in paragraph (d) of this section.
    (iv) An estimate of the maximum inventory of CCR ever on-site over 
the active life of the CCR unit.
    (v) An estimate of the largest area of the CCR unit ever requiring 
a final cover as required by paragraph (d) of this section at any time 
during the CCR unit's active life.
    (vi) A schedule for completing all activities necessary to satisfy 
the closure criteria in this section, including an estimate of the year 
in which all closure activities for the CCR unit will be completed. The 
schedule should provide sufficient information to describe the 
sequential steps that will be taken to close the CCR unit, including 
identification of major milestones such as coordinating with and 
obtaining necessary approvals and permits from other agencies, the 
dewatering and stabilization phases of CCR surface impoundment closure, 
or installation of

[[Page 39110]]

the final cover system, and the estimated timeframes to complete each 
step or phase of CCR unit closure. When preparing the written closure 
plan, if the owner or operator of a CCR unit estimates that the time 
required to complete closure will exceed the timeframes specified in 
paragraph (f)(1) of this section, the written closure plan must include 
the site-specific information, factors and considerations that would 
support any time extension sought under paragraph (f)(2) of this 
section.
    (2) Timeframes for preparing the initial written closure plan--(i) 
Existing CCR landfills and existing CCR surface impoundments. No later 
than October 17, 2016, the owner or operator of the CCR unit must 
prepare an initial written closure plan consistent with the 
requirements specified in paragraph (b)(1) of this section.
    (ii) New CCR landfills and new CCR surface impoundments, and any 
lateral expansion of a CCR unit. No later than the date of the initial 
receipt of CCR in the CCR unit, the owner or operator must prepare an 
initial written closure plan consistent with the requirements specified 
in paragraph (b)(1) of this section.
    (iii) CCR management units. Except as provided for in paragraph 
(b)(2)(v) of this section, no later than November 8, 2028, the owner or 
operator of the CCR management unit must prepare an initial written 
closure plan consistent with the requirements specified in paragraph 
(b)(1) of this section.
    (iv) Recordkeeping. The owner or operator has completed the written 
closure plan when the plan, including the certification required by 
paragraph (b)(4) of this section, has been placed in the facility's 
operating record as required by Sec.  257.105(i)(4).
    (v) Closure documentation for certain CCR management units. Owners 
and operators of a CCR management unit that completed closure of the 
unit in accordance with Sec.  257.102(d) prior to Friday, November 8, 
2024 or that meet the requirements in Sec.  257.101(g) must include in 
the facility evaluation report specified in Sec.  257.75 information on 
the completed closure, along with supporting documentation to 
demonstrate that the closure meets the performance standards in Sec.  
257.102(d) or the standards specified in Sec.  257.101(g).
    (3) Amendment of a written closure plan. (i) The owner or operator 
may amend the initial or any subsequent written closure plan developed 
pursuant to paragraph (b)(1) of this section at any time.
    (ii) The owner or operator must amend the written closure plan 
whenever:
    (A) There is a change in the operation of the CCR unit that would 
substantially affect the written closure plan in effect; or
    (B) Before or after closure activities have commenced, 
unanticipated events necessitate a revision of the written closure 
plan.
    (iii) The owner or operator must amend the closure plan at least 60 
days prior to a planned change in the operation of the facility or CCR 
unit, or no later than 60 days after an unanticipated event requires 
the need to revise an existing written closure plan. If a written 
closure plan is revised after closure activities have commenced for a 
CCR unit, the owner or operator must amend the current closure plan no 
later than 30 days following the triggering event.
    (4) Certification or approval. The owner or operator of the CCR 
unit must obtain a written certification from a qualified professional 
engineer or approval from the Participating State Director or approval 
from EPA where EPA is the permitting authority that the initial and any 
amendment of the written closure plan meets the requirements of this 
section.
    (c) Closure by removal of CCR. An owner or operator that elects to 
close a CCR unit by-removal of CCR must follow the procedures specified 
in either paragraph (c)(1) or (2) of this section. Closure by removal 
is complete when CCR has been removed; any areas affected by releases 
from the CCR unit have been removed or decontaminated; and groundwater 
monitoring concentrations of the constituents listed in appendix IV to 
this part do not exceed groundwater protection standards established 
pursuant to Sec.  257.95(h). Removal and decontamination activities 
include removing all CCR from the unit, CCR mixed with soils, and CCR 
included in berms, liners or other unit structures, and removing or 
decontaminating all areas affected by releases from the CCR unit.
    (1) Complete all removal and decontamination activities during the 
active life of the CCR unit. Within the timeframes specified in 
paragraph (f) of this section the owner or operator must do all of the 
following:
    (i) Complete removal of CCR and decontamination of all areas 
affected by releases from the CCR unit;
    (ii) Document that the standards in paragraph (c) of this section 
have been met. Documentation that groundwater protection standards have 
been met for the constituents listed in appendix IV to this part must 
consist of groundwater monitoring results that show no constituents 
were detected at statistically significant levels above the groundwater 
protection standards for either:
    (A) Two consecutive monitoring events; or
    (B) Three years, in accordance with Sec.  257.98(c); and
    (iii) Obtain the completion of closure certification or approval 
required by paragraph (f)(3) of this section.
    (2) Complete removal and decontamination activities during the 
active life and post-closure care period of the CCR unit. The owner or 
operator may close a CCR unit by completing all removal and 
decontamination activities, except for groundwater corrective action, 
during the active life of the CCR unit and by completing groundwater 
corrective action during the post-closure care period pursuant to the 
following procedures:
    (i) Within the timeframes specified in paragraph (f) of this 
section, document that CCR has been removed from the unit and any areas 
affected by releases from the CCR unit have been removed or 
decontaminated;
    (ii) Within the timeframes specified in paragraph (f) of this 
section, begin implementation of the remedy selected in accordance with 
Sec.  257.97 such that all components of the remedy are constructed, or 
otherwise in place, and operating as intended unless the owner or 
operator documents both that:
    (A) All applicable requirements in Sec. Sec.  257.96 through 257.98 
have been met; and
    (B) The active life of the unit could not be extended until 
implementation of the remedy consistent with Sec.  257.102(f);
    (iii) Complete groundwater corrective action as a post-closure care 
requirement as specified in Sec.  257.104(g);
    (iv) Amend the written closure plan required by paragraph (b) of 
this section and the written post-closure care plan required by Sec.  
257.104(d);
    (v) Within the timeframes specified in paragraph (f) of this 
section, obtain the completion of closure certification or approval 
required by paragraph (f)(3) of this section; and
    (vi) Within the timeframes specified in paragraph (f) of this 
section, record the notation on the deed to the property required by 
paragraph (i) of this section.
    (d) Closure performance standard when leaving CCR in place--
    (1) General performance standard. The owner or operator of a CCR 
unit must ensure that, at a minimum, the CCR unit is closed in a manner 
that will:

[[Page 39111]]

    (i) Control, minimize or eliminate, to the maximum extent feasible, 
post-closure infiltration of liquids into the waste and releases of 
CCR, leachate, or contaminated run-off to the ground or surface waters 
or to the atmosphere;
    (ii) Preclude the probability of future impoundment of water, 
sediment, or slurry;
    (iii) Include measures that provide for major slope stability to 
prevent the sloughing or movement of the final cover system during the 
closure and post-closure care period;
    (iv) Minimize the need for further maintenance of the CCR unit; and
    (v) Be completed in the shortest amount of time consistent with 
recognized and generally accepted good engineering practices.
    (2) Drainage and stabilization of CCR units. The owner or operator 
of any CCR unit must meet the requirements of paragraphs (d)(2)(i) and 
(ii) of this section prior to installing the final cover system 
required under paragraph (d)(3) of this section.
    (i) Free liquids must be eliminated by removing liquid wastes or 
solidifying the remaining wastes and waste residues.
    (ii) Remaining wastes must be stabilized sufficient to support the 
final cover system.
    (3) Final cover system. If a CCR unit is closed by leaving CCR in 
place, the owner or operator must install a final cover system that is 
designed to minimize infiltration and erosion, and at a minimum, meets 
the requirements of paragraph (d)(3)(i) of this section, or the 
requirements of the alternative final cover system specified in 
paragraph (d)(3)(ii) of this section.
    (i) The final cover system must be designed and constructed to meet 
the criteria in paragraphs (d)(3)(i)(A) through (D) of this section. 
The design of the final cover system must be included in the written 
closure plan required by paragraph (b) of this section.
    (A) The permeability of the final cover system must be less than or 
equal to the permeability of any bottom liner system or natural 
subsoils present, or a permeability no greater than 1 x 10-5 
cm/sec, whichever is less.
    (B) The infiltration of liquids through the closed CCR unit must be 
minimized by the use of an infiltration layer that contains a minimum 
of 18 inches of earthen material.
    (C) The erosion of the final cover system must be minimized by the 
use of an erosion layer that contains a minimum of six inches of 
earthen material that is capable of sustaining native plant growth.
    (D) The disruption of the integrity of the final cover system must 
be minimized through a design that accommodates settling and 
subsidence.
    (ii) The owner or operator may select an alternative final cover 
system design, provided the alternative final cover system is designed 
and constructed to meet the criteria in paragraphs (d)(3)(ii)(A) 
through (C) of this section. The design of the final cover system must 
be included in the written closure plan required by paragraph (b) of 
this section.
    (A) The design of the final cover system must include an 
infiltration layer that achieves an equivalent reduction in 
infiltration as the infiltration layer specified in paragraphs 
(d)(3)(i)(A) and (B) of this section.
    (B) The design of the final cover system must include an erosion 
layer that provides equivalent protection from wind or water erosion as 
the erosion layer specified in paragraph (d)(3)(i)(C) of this section.
    (C) The disruption of the integrity of the final cover system must 
be minimized through a design that accommodates settling and 
subsidence.
    (iii) The owner or operator of the CCR unit must obtain a written 
certification from a qualified professional engineer or approval from 
the Participating State Director or approval from EPA where EPA is the 
permitting authority that the design of the final cover system meets 
the requirements of this section.
    (e) Initiation of closure activities. Except as provided for in 
paragraph (e)(4) of this section and Sec.  257.103, the owner or 
operator of a CCR unit must commence closure of the CCR unit no later 
than the applicable timeframes specified in either paragraph (e)(1) or 
(2) of this section.
    (1) The owner or operator must commence closure of the CCR unit no 
later than 30 days after the date on which the CCR unit either:
    (i) Receives the known final receipt of waste, either CCR or any 
non-CCR waste stream; or
    (ii) Removes the known final volume of CCR from the CCR unit for 
the purpose of beneficial use of CCR.
    (2)(i) Except as provided by paragraph (e)(2)(ii) of this section, 
the owner or operator must commence closure of a CCR unit that has not 
received CCR or any non-CCR waste stream or is no longer removing CCR 
for the purpose of beneficial use within two years of the last receipt 
of waste or within two years of the last removal of CCR material for 
the purpose of beneficial use.
    (ii) Notwithstanding paragraph (e)(2)(i) of this section, the owner 
or operator of the CCR unit may secure an additional two years to 
initiate closure of the idle unit provided the owner or operator 
provides written documentation that the CCR unit will continue to 
accept wastes or will start removing CCR for the purpose of beneficial 
use. The documentation must be supported by, at a minimum, the 
information specified in paragraphs (e)(2)(ii)(A) and (B) of this 
section. The owner or operator may obtain two-year extensions provided 
the owner or operator continues to be able to demonstrate that there is 
reasonable likelihood that the CCR unit will accept wastes in the 
foreseeable future or will remove CCR from the unit for the purpose of 
beneficial use. The owner or operator must place each completed 
demonstration, if more than one time extension is sought, in the 
facility's operating record as required by Sec.  257.105(i)(5) prior to 
the end of any two-year period.
    (A) Information documenting that the CCR unit has remaining storage 
or disposal capacity or that the CCR unit can have CCR removed for the 
purpose of beneficial use; and
    (B) Information demonstrating that that there is a reasonable 
likelihood that the CCR unit will resume receiving CCR or non-CCR waste 
streams in the foreseeable future or that CCR can be removed for the 
purpose of beneficial use. The narrative must include a best estimate 
as to when the CCR unit will resume receiving CCR or non-CCR waste 
streams. The situations listed in paragraphs (e)(2)(ii)(B)(1) through 
(4) of this section are examples of situations that would support a 
determination that the CCR unit will resume receiving CCR or non-CCR 
waste streams in the foreseeable future.
    (1) Normal plant operations include periods during which the CCR 
unit does not receive CCR or non-CCR waste streams, such as the 
alternating use of two or more CCR units whereby at any point in time 
one CCR unit is receiving CCR while CCR is being removed from a second 
CCR unit after its dewatering.
    (2) The CCR unit is dedicated to a coal-fired boiler unit that is 
temporarily idled (e.g., CCR is not being generated) and there is a 
reasonable likelihood that the coal-fired boiler will resume operations 
in the future.
    (3) The CCR unit is dedicated to an operating coal-fired boiler 
(i.e., CCR is being generated); however, no CCR are being placed in the 
CCR unit because the CCR are being entirely diverted to beneficial 
uses, but there is a reasonable likelihood that the CCR unit will again 
be used in the foreseeable future.
    (4) The CCR unit currently receives only non-CCR waste streams and 
those

[[Page 39112]]

non-CCR waste streams are not generated for an extended period of time, 
but there is a reasonable likelihood that the CCR unit will again 
receive non-CCR waste streams in the future.
    (iii) In order to obtain additional time extension(s) to initiate 
closure of a CCR unit beyond the two years provided by paragraph 
(e)(2)(i) of this section, the owner or operator of the CCR unit must 
include with the demonstration required by paragraph (e)(2)(ii) of this 
section the following statement signed by the owner or operator or an 
authorized representative:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (3) For purposes of this subpart, closure of the CCR unit has 
commenced if the owner or operator has ceased placing waste and 
completes any of the following actions or activities:
    (i) Taken any steps necessary to implement the written closure plan 
required by paragraph (b) of this section;
    (ii) Submitted a completed application for any required state or 
agency permit or permit modification; or
    (iii) Taken any steps necessary to comply with any state or other 
agency standards that are a prerequisite, or are otherwise applicable, 
to initiating or completing the closure of a CCR unit.
    (4) The timeframes specified in paragraphs (e)(1) and (2) of this 
section do not apply to any of the following owners or operators:
    (i) [Reserved]
    (ii) An owner or operator of an existing unlined CCR surface 
impoundment closing the CCR unit as required by Sec.  257.101(a);
    (iii) An owner or operator of an existing CCR surface impoundment 
closing the CCR unit as required by Sec.  257.101(b);
    (iv) An owner or operator of a new CCR surface impoundment closing 
the CCR unit as required by Sec.  257.101(c); or
    (v) An owner or operator of an existing CCR landfill closing the 
CCR unit as required by Sec.  257.101(d).
    (f) Completion of closure activities.
    (1) Except as provided for in paragraph (f)(2) of this section, the 
owner or operator must complete closure of the CCR unit:
    (i) For existing and new CCR landfills and any lateral expansion of 
a CCR landfill, within six months of commencing closure activities.
    (ii) For existing and new CCR surface impoundments and any lateral 
expansion of a CCR surface impoundment, within five years of commencing 
closure activities.
    (iii) For CCR management units, within five years of commencing 
closure activities.
    (2)(i) Extensions of closure timeframes. The timeframes for 
completing closure of a CCR unit specified under paragraphs (f)(1) of 
this section may be extended if the owner or operator can demonstrate 
that it was not feasible to complete closure of the CCR unit within the 
required timeframes due to factors beyond the facility's control. If 
the owner or operator is seeking a time extension beyond the time 
specified in the written closure plan as required by paragraph (b)(1) 
of this section, the demonstration must include a narrative discussion 
providing the basis for additional time beyond that specified in the 
closure plan. The owner or operator must place each completed 
demonstration, if more than one time extension is sought, in the 
facility's operating record as required by Sec.  257.105(i)(6) prior to 
the end of any two-year period. Factors that may support such a 
demonstration include:
    (A) Complications stemming from the climate and weather, such as 
unusual amounts of precipitation or a significantly shortened 
construction season;
    (B) Time required to dewater a CCR unit due to the volume of CCR 
contained in the CCR unit or the characteristics of the CCR in the 
unit;
    (C) The geology and terrain surrounding the CCR unit will affect 
the amount of material needed to close the CCR unit; or
    (D) Time required or delays caused by the need to coordinate with 
and obtain necessary approvals and permits from a state or other 
agency.
    (ii) Maximum time extensions. (A) CCR surface impoundments of 40 
acres or smaller may extend the time to complete closure by no longer 
than two years.
    (B) CCR surface impoundments larger than 40 acres may extend the 
timeframe to complete closure of the CCR unit multiple times, in two-
year increments. For each two-year extension sought, the owner or 
operator must substantiate the factual circumstances demonstrating the 
need for the extension. No more than a total of five two-year 
extensions may be obtained for any CCR surface impoundment.
    (C) Except as provided in paragraph (f)(2)(ii)(D) of this section, 
CCR landfills may extend the timeframe to complete closure of the CCR 
unit multiple times, in one-year increments. For each one-year 
extension sought, the owner or operator must substantiate the factual 
circumstances demonstrating the need for the extension. No more than a 
total of two one-year extensions may be obtained for any CCR landfill.
    (D) CCR landfills that intersect with groundwater are eligible for 
the time extensions available to CCR units in paragraph (f)(2)(ii)(B) 
of this section, provided the owner or operator documents that 
groundwater intersects the CCR unit in the closure plan.
    (E) CCR management units of 40 acres or smaller may extend the time 
to complete closure by no longer than two years.
    (F) CCR management units larger than 40 acres may extend the 
timeframe to complete closure of the CCR management unit multiple 
times, in two-year increments. For each two-year extension sought, the 
owner or operator must substantiate the factual circumstances 
demonstrating the need for the extension. No more than a total of five 
two-year extensions may be obtained for any CCR management unit.
    (iii) In order to obtain additional time extension(s) to complete 
closure of a CCR unit beyond the times provided by paragraph (f)(1) of 
this section, the owner or operator of the CCR unit must include with 
the demonstration required by paragraph (f)(2)(i) of this section the 
following statement signed by the owner or operator or an authorized 
representative:

    I certify under penalty of law that I have personally examined 
and am familiar with the information submitted in this demonstration 
and all attached documents, and that, based on my inquiry of those 
individuals immediately responsible for obtaining the information, I 
believe that the submitted information is true, accurate, and 
complete. I am aware that there are significant penalties for 
submitting false information, including the possibility of fine and 
imprisonment.

    (3) Upon completion, the owner or operator of the CCR unit must 
obtain a certification from a qualified professional engineer or 
approval from the Participating State Director or approval from EPA 
where EPA is the permitting authority verifying that closure has been 
completed in accordance with the closure plan specified in paragraph 
(b) of this section and the requirements of this section.
    (g) Notification of intent to close. No later than the date the 
owner or operator initiates closure of a CCR unit, the

[[Page 39113]]

owner or operator must prepare a notification of intent to close a CCR 
unit. The notification must include the certification by a qualified 
professional engineer or the approval from the Participating State 
Director or the approval from EPA where EPA is the permitting authority 
for the design of the final cover system as required by Sec.  
257.102(d)(3)(iii), if applicable. The owner or operator has completed 
the notification when it has been placed in the facility's operating 
record as required by Sec.  257.105(i)(7).
    (h) Notification of completion of closure. Within 30 days of 
completion of closure of the CCR unit, the owner or operator must 
prepare a notification of closure of a CCR unit. The notification must 
include the certification by a qualified professional engineer or the 
approval from the Participating State Director or the approval from EPA 
where EPA is the permitting authority as required by Sec.  
257.102(f)(3). The owner or operator has completed the notification 
when it has been placed in the facility's operating record as required 
by Sec.  257.105(i)(8).
    (i) Deed notations. (1) Except as provided by paragraph (i)(4) of 
this section, following closure of a CCR unit, the owner or operator 
must record a notation on the deed to the property, or some other 
instrument that is normally examined during title search.
    (2) The notation on the deed must in perpetuity notify any 
potential purchaser of the property that:
    (i) The land has been used as a CCR unit; and
    (ii) Its use is restricted under the post-closure care requirements 
as provided by Sec.  257.104(d)(1)(iii).
    (3) Within 30 days of recording a notation on the deed to the 
property, the owner or operator must prepare a notification stating 
that the notation has been recorded. The owner or operator has 
completed the notification when it has been placed in the facility's 
operating record as required by Sec.  257.105(i)(9).
    (4) An owner or operator that closes a CCR unit in accordance with 
paragraph (c)(1) of this section is not subject to the requirements of 
paragraphs (i)(1) through (3) of this section.
    (j) Recordkeeping, notification, and internet requirements. The 
owner or operator of the CCR unit must comply with the closure 
recordkeeping requirements specified in Sec.  257.105(i), the closure 
notification requirements specified in Sec.  257.106(i), and the 
closure internet requirements specified in Sec.  257.107(i).
    (k) Criteria to retrofit an existing CCR surface impoundment. (1) 
To retrofit an existing CCR surface impoundment, the owner or operator 
must:
    (i) First remove all CCR, including any contaminated soils and 
sediments from the CCR unit; and
    (ii) Comply with the requirements in Sec.  257.72.
    (iii) A CCR surface impoundment undergoing a retrofit remains 
subject to all other requirements of this subpart, including the 
requirement to conduct any necessary corrective action.
    (2) Written retrofit plan--(i) Content of the plan. The owner or 
operator must prepare a written retrofit plan that describes the steps 
necessary to retrofit the CCR unit consistent with recognized and 
generally accepted good engineering practices. The written retrofit 
plan must include, at a minimum, all of the following information:
    (A) A narrative description of the specific measures that will be 
taken to retrofit the CCR unit in accordance with this section.
    (B) A description of the procedures to remove all CCR and 
contaminated soils and sediments from the CCR unit.
    (C) An estimate of the maximum amount of CCR that will be removed 
as part of the retrofit operation.
    (D) An estimate of the largest area of the CCR unit that will be 
affected by the retrofit operation.
    (E) A schedule for completing all activities necessary to satisfy 
the retrofit criteria in this section, including an estimate of the 
year in which retrofit activities of the CCR unit will be completed.
    (ii) Timeframes for preparing the initial written retrofit plan. 
(A) No later than 60 days prior to date of initiating retrofit 
activities, the owner or operator must prepare an initial written 
retrofit plan consistent with the requirements specified in paragraph 
(k)(2) of this section. For purposes of this subpart, initiation of 
retrofit activities has commenced if the owner or operator has ceased 
placing waste in the unit and completes any of the following actions or 
activities:
    (1) Taken any steps necessary to implement the written retrofit 
plan;
    (2) Submitted a completed application for any required state or 
agency permit or permit modification; or
    (3) Taken any steps necessary to comply with any state or other 
agency standards that are a prerequisite, or are otherwise applicable, 
to initiating or completing the retrofit of a CCR unit.
    (B) The owner or operator has completed the written retrofit plan 
when the plan, including the certification required by paragraph 
(k)(2)(iv) of this section, has been placed in the facility's operating 
record as required by Sec.  257.105(j)(1).
    (iii) Amendment of a written retrofit plan. (A) The owner or 
operator may amend the initial or any subsequent written retrofit plan 
at any time.
    (B) The owner or operator must amend the written retrofit plan 
whenever:
    (1) There is a change in the operation of the CCR unit that would 
substantially affect the written retrofit plan in effect; or
    (2) Before or after retrofit activities have commenced, 
unanticipated events necessitate a revision of the written retrofit 
plan.
    (C) The owner or operator must amend the retrofit plan at least 60 
days prior to a planned change in the operation of the facility or CCR 
unit, or no later than 60 days after an unanticipated event requires 
the revision of an existing written retrofit plan. If a written 
retrofit plan is revised after retrofit activities have commenced for a 
CCR unit, the owner or operator must amend the current retrofit plan no 
later than 30 days following the triggering event.
    (iv) Certification or approval. The owner or operator of the CCR 
unit must obtain a written certification from a qualified professional 
engineer or an approval from the Participating State Director or an 
approval from EPA where EPA is the permitting authority that the 
activities outlined in the written retrofit plan, including any 
amendment of the plan, meet the requirements of this section.
    (3) Deadline for completion of activities related to the retrofit 
of a CCR unit. Any CCR surface impoundment that is being retrofitted 
must complete all retrofit activities within the same time frames and 
procedures specified for the closure of a CCR surface impoundment in 
Sec.  257.102(f) or, where applicable, Sec.  257.103.
    (4) Certification or approval. Upon completion, the owner or 
operator must obtain a written certification from a qualified 
professional engineer or an approval from the Participating State 
Director or an approval from EPA where EPA is the permitting authority 
verifying that the retrofit activities have been completed in 
accordance with the retrofit plan specified in paragraph (k)(2) of this 
section and the requirements of this section.
    (5) Notification of intent to retrofit. No later than the date the 
owner or operator initiates the retrofit of a CCR unit, the owner or 
operator must prepare a notification of intent to retrofit a CCR

[[Page 39114]]

unit. The owner or operator has completed the notification when it has 
been placed in the facility's operating record as required by Sec.  
257.105(j)(5).
    (6) Notification of completion of retrofit activities. Within 30 
days of completing the retrofit activities specified in paragraph 
(k)(1) of this section, the owner or operator must prepare a 
notification of completion of retrofit activities. The notification 
must include the certification from a qualified professional engineer 
or an approval from the Participating State Director or an approval 
from EPA where EPA is the permitting authority has is required by 
paragraph (k)(4) of this section. The owner or operator has completed 
the notification when it has been placed in the facility's operating 
record as required by Sec.  257.105(j)(6).
    (7) Cease retrofit and initiation of closure. At any time after the 
initiation of a CCR unit retrofit, the owner or operator may cease the 
retrofit and initiate closure of the CCR unit in accordance with the 
requirements of Sec.  257.102.
    (8) Recordkeeping, notification, and internet requirements. The 
owner or operator of the CCR unit must comply with the retrofit 
recordkeeping requirements specified in Sec.  257.105(j), the retrofit 
notification requirements specified in Sec.  257.106(j), and the 
retrofit internet requirements specified in Sec.  257.107(j).

0
21. Amend Sec.  257.104 by:
0
a. Revising paragraphs (a) and (c)(1);
0
b. Adding paragraph (c)(3);
0
c. Revising paragraph (d)(2); and
0
d. Adding paragraph (g).
    The additions and revisions read as follows:


Sec.  257.104  Post-closure care requirements.

    (a) Applicability. (1) Except as provided by paragraph (a)(2) of 
this section, Sec.  257.104 applies to the owners or operators of CCR 
units that are subject to the closure criteria under Sec.  257.102.
    (2) An owner or operator of a CCR unit that elects to close a CCR 
unit by removing CCR as provided by Sec.  257.102(c)(1) is not subject 
to the post-closure care criteria under this section.
* * * * *
    (c) * * *
    (1) Except as provided by paragraph (c)(2) and (3) of this section, 
the owner or operator of the CCR unit must conduct post-closure care 
for 30 years.
* * * * *
    (3) An owner or operator closing a unit pursuant to Sec.  
257.102(c)(2) must complete groundwater corrective action in accordance 
with Sec.  257.98(c).
    (d) * * *
    (2) Deadline to prepare the initial written post-closure plan--(i) 
Existing CCR landfills and existing CCR surface impoundments. No later 
than October 17, 2016, the owner or operator of the CCR unit must 
prepare an initial written post-closure plan consistent with the 
requirements specified in paragraph (d)(1) of this section.
    (ii) New CCR landfills, new CCR surface impoundments, and any 
lateral expansion of a CCR unit. No later than the date of the initial 
receipt of CCR in the CCR unit, the owner or operator must prepare an 
initial written post-closure plan consistent with the requirements 
specified in paragraph (d)(1) of this section.
    (iii) CCR management units. No later than Wednesday, November 8, 
2028, the owner or operator of a CCR management unit must prepare an 
initial written post-closure care plan as set forth in paragraph (d)(1) 
of this section.
    (iv) Recordkeeping. The owner or operator has completed the written 
post-closure plan when the plan, including the certification required 
by paragraph (d)(4) of this section, has been placed in the facility's 
operating record as required by Sec.  257.105(i)(4).
* * * * *
    (g) Removal of a deed notation. The owner or operator of a CCR unit 
closed pursuant to Sec. Sec.  257.102(c)(2) and 257.104 may remove the 
notation from the deed specified in Sec.  257.102(i) upon:
    (1) Completion of groundwater corrective action demonstrating that 
any areas affected by releases from the CCR unit do not exceed the 
groundwater protection standards established pursuant to Sec.  
257.95(h) for constituents listed in appendix IV to this part; and
    (2) Completion of the notification of completion of post-closure 
care period required by paragraph (e) of this section.
* * * * *

0
22. Revise Sec.  257.105 to read as follows:


Sec.  257.105  Recordkeeping requirements.

    (a) Operating Record. Each owner or operator of a CCR unit subject 
to the requirements of this subpart must date and maintain files of all 
information required by this section in a written operating record at 
their facility. Each file must indicate the date the file was placed in 
the operating record.
    (b) Document Retention. Unless specified otherwise, each file must 
be retained for at least five years following the date of each 
occurrence, measurement, maintenance, corrective action, report, 
record, or study.
    (c) Recordkeeping for multiple CCR units. An owner or operator of 
more than one CCR unit subject to the provisions of this subpart may 
comply with the requirements of this section in one recordkeeping 
system provided the system identifies each file by the name of each CCR 
unit. The files may be maintained on microfilm, on a computer, on 
computer disks, on a storage system accessible by a computer, on 
magnetic tape disks, or on microfiche.
    (d) State Director and/or appropriate Tribal authority 
notification. The owner or operator of a CCR unit must submit to the 
State Director and/or appropriate Tribal authority any demonstration or 
documentation required by this subpart, if requested, when such 
information is not otherwise available on the owner or operator's CCR 
website.
    (e) Location restrictions. The owner or operator of a CCR unit 
subject to this subpart must place the demonstrations documenting 
whether or not the CCR unit is in compliance with the requirements 
under Sec. Sec.  257.60(a), 257.61(a), 257.62(a), 257.63(a), and 
257.64(a), as it becomes available, in the facility's operating record, 
except each location restrictions demonstration must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g).
    (f) Design criteria. The owner or operator of a CCR unit subject to 
this subpart must place the following information, as it becomes 
available, in the facility's operating record:
    (1) The design and construction certifications as required by Sec.  
257.70(e) and (f), except each certification must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (b) of this section.
    (2) The documentation of liner type as required by Sec.  257.71(a), 
except each liner type documentation must be maintained for five years 
after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (b) of this section.
    (3) The design and construction certifications as required by Sec.  
257.72(c) and (d), except each certification must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in

[[Page 39115]]

accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (4) Documentation prepared by the owner or operator stating that 
the permanent identification marker was installed as required by 
Sec. Sec.  257.73(a)(1) and 257.74(a)(1), except each document must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or until completion of post-closure 
care in accordance with Sec.  257.104(e) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (5) The initial and periodic hazard potential classification 
assessments as required by Sec. Sec.  257.73(a)(2) and 257.74(a)(2), 
except each hazard potential classification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (b) of this section.
    (6) The emergency action plan (EAP), and any amendment of the EAP, 
as required by Sec. Sec.  257.73(a)(3) and 257.74(a)(3), except each 
EAP must be maintained for five years after completion of closure by 
removal in accordance with Sec.  257.102(c) or until completion of 
post-closure care in accordance with Sec.  257.104(e) or (g) 
irrespective of the time requirement specified in paragraph (b) of this 
section.
    (7) Documentation prepared by the owner or operator recording the 
annual face-to-face meeting or exercise between representatives of the 
owner or operator of the CCR unit and the local emergency responders as 
required by Sec. Sec.  257.73(a)(3)(i)(E) and 257.74(a)(3)(i)(E), 
except each document must be maintained for five years after completion 
of closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (8) Documentation prepared by the owner or operator recording all 
activations of the emergency action plan as required by Sec. Sec.  
257.73(a)(3)(v) and 257.74(a)(3)(v), except each documentation of EAP 
activations must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (9) The history of construction, and any revisions of it, as 
required by Sec.  257.73(c), except each history of construction must 
be maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or (2) or until completion of post-
closure care in accordance with Sec.  257.104(e) or (g) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (10) The initial and periodic structural stability assessments as 
required by Sec. Sec.  257.73(d) and 257.74(d), except each structural 
stability assessment must be maintained for five years after completion 
of closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (11) Documentation detailing the corrective measures taken to 
remedy the deficiency or release as required by Sec. Sec.  257.73(d)(2) 
and 257.74(d)(2), except each document must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (12) The initial and periodic safety factor assessments as required 
by Sec. Sec.  257.73(e) and 257.74(e), except each safety factor 
assessment must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (13) The design and construction plans, and any revisions of it, as 
required by Sec.  257.74(c), except the design and construction plans 
must be maintained for five years after completion of closure by 
removal in accordance with Sec.  257.102(c)(1) or (2) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (b) of 
this section.
    (14) The application and any supplemental materials submitted in 
support of the application as required by Sec.  257.71(d)(1)(i)(E), 
except each application and supplemental materials must be maintained 
for five years after completion of closure by removal in accordance 
with Sec.  257.102(c)(1) or (2) or until completion of post-closure 
care in accordance with Sec.  257.104(e) or (g) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (15) The alternative liner demonstration as required by Sec.  
257.71(d)(1)(ii)(D).
    (16) The alternative liner demonstration extension request as 
required by Sec.  257.71(d)(2)(ii)(D).
    (17) The documentation prepared for the preliminary demonstration 
as required by Sec.  257.71(d)(2)(ii)(E).
    (18) The notification of an incomplete application as required by 
Sec.  257.71(d)(2)(iii)(B).
    (19) The decision on the application as required by Sec.  
257.71(d)(2)(iii)(F), except each decision must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (20) The final decision on the alternative liner demonstration as 
required by Sec.  257.71(d)(2)(vii).
    (21) The alternative source demonstration as required under Sec.  
257.71(d)(2)(ix)(A)(4).
    (22) The final decision on the alternative source demonstration as 
required under Sec.  257.71(d)(2)(ix)(A)(5).
    (23) The final decision on the trend analysis as required under 
Sec.  257.71(d)(2)(ix)(B)(3).
    (24) The decision that the alternative source demonstration has 
been withdrawn as required under Sec.  257.71(d)(2)(ix)(C).
    (25) The facility evaluation report part 1 as required by Sec.  
257.75(c), except the facility evaluation report part 1 must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or (2) or until completion of post-
closure care in accordance with Sec.  257.104(e) or (g) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (26) The facility evaluation report part 2 as required by Sec.  
257.75(d), except the facility evaluation report part 2 must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or (2) or until completion of post-
closure care in accordance with Sec.  257.104(e) or (g) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (g) Operating criteria. The owner or operator of a CCR unit subject 
to this

[[Page 39116]]

subpart must place the following information, as it becomes available, 
in the facility's operating record:
    (1) The CCR fugitive dust control plan, and any subsequent 
amendment of the plan, required by Sec.  257.80(b), except each 
fugitive dust control plan must be maintained for five years after 
closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
completes post-closure care in accordance with Sec.  257.104(e) or (g) 
is completed at the last CCR unit at the facility irrespective of the 
time requirement specified in paragraph (b) of this section.
    (2) The annual CCR fugitive dust control report required by Sec.  
257.80(c), except each fugitive dust control report must be maintained 
for five years after closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or post-closure care in accordance with Sec.  
257.104(e) or (g) is completed at the last CCR unit at the facility 
irrespective of the time requirement specified in paragraph (b) of this 
section.
    (3) The initial and periodic run-on and run-off control system 
plans as required by Sec.  257.81(c), except each plan must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or (2) or until completion of post-
closure care in accordance with Sec.  257.104(e) or (g) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (4) The initial and periodic inflow design flood control system 
plan as required by Sec.  257.82(c), except each plan must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or (2) or until completion of post-
closure care in accordance with Sec.  257.104(e) or (g) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (5) Documentation recording the results of each inspection and 
instrumentation monitoring by a qualified person as required by Sec.  
257.83(a), except each document must be maintained for five years after 
completion of closure by removal in accordance with Sec.  257.102(c)(1) 
or (2) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (b) of this section.
    (6) The periodic inspection report as required by Sec.  
257.83(b)(2), except each inspection report must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (7) Documentation detailing the corrective measures taken to remedy 
the deficiency or release as required by Sec. Sec.  257.83(b)(5) and 
257.84(b)(5), except each document must be maintained for five years 
after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (8) Documentation recording the results of the weekly inspection by 
a qualified person as required by Sec.  257.84(a), except each 
inspection report must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (9) The periodic inspection report as required by Sec.  
257.84(b)(2), except each inspection report must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (h) Groundwater monitoring and corrective action. The owner or 
operator of a CCR unit subject to this subpart must place the following 
information, as it becomes available, in the facility's operating 
record:
    (1) The annual groundwater monitoring and corrective action report 
as required by Sec.  257.90(e), except each annual groundwater 
monitoring and corrective action report must be maintained for five 
years after the last CCR unit at the facility either completes closure 
by removal in accordance with Sec.  257.102(c)(1) or completes post-
closure care in accordance with Sec.  257.104(e) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (2) Documentation of the design, installation, development, and 
decommissioning of any monitoring wells, piezometers and other 
measurement, sampling, and analytical devices as required by Sec.  
257.91(e)(1), except each document must be maintained for five years 
after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (3) The groundwater monitoring system certification as required by 
Sec.  257.91(f), except each certification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (4) The selection of a statistical method certification as required 
by Sec.  257.93(f)(6), except each certification must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c)(1) or completion of post-closure care in accordance 
with Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (5) Within 30 days of establishing an assessment monitoring 
program, the notification as required by Sec.  257.94(e)(3).
    (6) The results of appendices III and IV to this part constituent 
concentrations measured as required by Sec.  257.95(d)(1).
    (7) Within 30 days of returning to a detection monitoring program, 
the notification as required by Sec.  257.95(e).
    (8) Within 30 days of detecting one or more constituents in 
appendix IV to this part at statistically significant levels above the 
groundwater protection standard, the notifications as required by Sec.  
257.95(g).
    (9) Within 30 days of initiating the assessment of corrective 
measures requirements, the notification as required by Sec.  
257.95(g)(5).
    (10) The completed assessment of corrective measures as required by 
Sec.  257.96(d), except each certification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (11) Documentation prepared by the owner or operator recording the 
public meeting for the corrective measures assessment as required by 
Sec.  257.96(e), except each certification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.

[[Page 39117]]

    (12) The semiannual report describing the progress in selecting and 
designing the remedy and the selection of remedy report as required by 
Sec.  257.97(a), except that the selection of remedy report must be 
maintained until the remedy has been completed.
    (13) Within 30 days of completing the remedy, the notification as 
required by Sec.  257.98(e), except each notification must be 
maintained for five years after completion of the remedy selected 
pursuant to Sec.  257.97 irrespective of the time requirement specified 
in paragraph (b) of this section.
    (14) The demonstration, including long-term performance data, 
supporting the suspension of groundwater monitoring requirements as 
required by Sec.  257.90(g), except each document must be maintained 
for five years after the last unit at the facility completes post-
closure care in accordance with Sec.  257.104(e) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (i) Closure and post-closure care. The owner or operator of a CCR 
unit subject to this subpart must place the following information, as 
it becomes available, in the facility's operating record:
    (1) The notification of intent to initiate closure of the CCR unit 
as required by Sec.  257.100(c)(1).
    (2) The annual progress reports of closure implementation as 
required by Sec.  257.100(c)(2)(i) and (ii).
    (3) The notification of closure completion as required by Sec.  
257.100(c)(3).
    (4) The written closure plan, and any amendment of the plan, as 
required by Sec.  257.102(b), except that only the most recent closure 
plan must be maintained for five years after completion of closure by 
removal in accordance with Sec.  257.102(c)(1) or completion of post-
closure care in accordance with Sec.  257.104(e) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (5) The written demonstration(s), including the certification 
required by Sec.  257.102(e)(2)(iii), for a time extension for 
initiating closure as required by Sec.  257.102(e)(2)(ii), except each 
demonstration must be maintained until notice of completion of closure 
is placed in the operating record in accordance with Sec.  257.102(h) 
irrespective of the time requirement specified in paragraph (b) of this 
section.
    (6) The written demonstration(s), including the certification 
required by Sec.  257.102(f)(2)(iii), for a time extension for 
completing closure as required by Sec.  257.102(f)(2)(i), except each 
demonstration must be maintained for five years after completion of 
closure in accordance with Sec.  257.102(c) or (d) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (7) The notification of intent to close a CCR unit as required by 
Sec.  257.102(g), except each notification must be maintained for five 
years after completion of closure in accordance with Sec.  257.102(c) 
or (d) irrespective of the time requirement specified in paragraph (b) 
of this section.
    (8) The notification of completion of closure of a CCR unit as 
required by Sec.  257.102(h), except each notification must be 
maintained for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or completion of post-closure care 
in accordance with Sec.  257.104(e) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (9) The notification recording a notation on the deed as required 
by Sec.  257.102(i), except each notification must be maintained for 
five years after completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (10) The notification of intent to comply with the alternative 
closure requirements as required by Sec.  257.103(c)(1), except each 
notification must be maintained for five years after completion of 
closure in accordance with Sec.  257.102(c) or (d) irrespective of the 
time requirement specified in paragraph (b) of this section.
    (11) The annual progress reports under the alternative closure 
requirements as required by Sec.  257.103(c)(2), except each report 
must be maintained for five years after completion of closure in 
accordance with Sec.  257.102(c) or (d) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (12) The written post-closure plan, and any amendment of the plan, 
as required by Sec.  257.104(d), except that only the most recent post-
closure plan must be maintained for five years after completion of 
post-closure care in accordance with Sec.  257.104(e) irrespective of 
the time requirement specified in paragraph (b) of this section.
    (13) The notification of completion of post-closure care period as 
required by Sec.  257.104(e), except each notification must be 
maintained for five years after completion of post-closure care in 
accordance with Sec.  257.104(e) irrespective of the time requirement 
specified in paragraph (b) of this section.
    (14) The notification of intent to comply with the site-specific 
alternative to initiation of closure due to development of alternative 
capacity infeasible as required by Sec.  257.103(f)(1)(ix)(A), except 
each notification must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c)(1) or (2) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (b) of this section.
    (15) The approved or denied demonstration for the site-specific 
alternative to initiation of closure due to development of alternative 
capacity infeasible as required by Sec.  257.103(f)(1)(ix)(B), except 
each approval or denial must be maintained for five years after 
completion of closure by removal in accordance with Sec.  257.102(c)(1) 
or (2) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (b) of this section.
    (16) The notification for requesting additional time to the 
alternative cease receipt of waste deadline as required by Sec.  
257.103(f)(1)(ix)(C), except each notification must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (17) The semi-annual progress reports for the site-specific 
alternative to initiation of closure due to development of alternative 
capacity being infeasible as required by Sec.  257.103(f)(1)(xi), 
except each semi-annual progress report must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (18) The notification of intent to comply with the site-specific 
alternative to initiation of closure due to permanent cessation of a 
coal-fired boiler(s) by a date certain as required by Sec.  
257.103(f)(2)(viii), except each notification must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.

[[Page 39118]]

    (19) The approved or denied demonstration for the site-specific 
alternative to initiation of closure due to permanent cessation of a 
coal-fired boiler(s) by a date certain as required by Sec.  
257.103(f)(2)(ix), except each demonstration must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (20) The annual progress report for the site-specific alternative 
to initiation of closure due to permanent cessation of a coal-fired 
boiler(s) by a date certain as required by Sec.  257.103(f)(2)(x), 
except each annual progress report must be maintained for five years 
after completion of closure by removal in accordance with Sec.  
257.102(c)(1) or (2) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (k) Legacy CCR surface impoundments. In addition to the information 
specified in paragraphs (e) through (j) of this section, the owner or 
operator of a legacy CCR surface impoundment subject to this subpart 
must place the following information, as it becomes available, in the 
facility's operating record:
    (1) The applicability report required by Sec.  257.100(f)(1), 
including the certification required by Sec.  257.100(f)(1)(i), except 
each report must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (b) of 
this section.
    (2) The applicability extension reports required by Sec.  
257.100(f)(1)(iii)(C), except each report must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (b) of this section.
    (3) The notification of field investigation conclusion required by 
Sec.  257.100(f)(1)(iii)(F), except the notification must be maintained 
for five years after completion of closure by removal in accordance 
with Sec.  257.102(c) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (b) of this section.
    (4) The notification of intent to certify closure required by Sec.  
257.100(h)(1)(i), except the notification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.100(h)(1) or Sec.  257.102(c)(2) irrespective of the time 
requirement specified in paragraph (b) of this section.

0
23. Amend Sec.  257.106 by:
0
a. Revising paragraphs (a), (b), (c), and (d);
0
b. Adding paragraphs (f)(24) and (25) and (k).
    The revisions and additions read as follows:


Sec.  257.106  Notification requirements.

    (a) Deadline to submit notification to the relevant State Director 
and/or appropriate Tribal authority. The notifications required under 
paragraphs (e) through (i) of this section must be sent to the relevant 
State Director and/or appropriate Tribal authority before the close of 
business on the day the notification is required to be completed. For 
purposes of this section, before the close of business means the 
notification must be postmarked or sent by electronic mail (email). If 
a notification deadline falls on a weekend or federal holiday, the 
notification deadline is automatically extended to the next business 
day.
    (b) Notifications to Tribal authority. If any CCR unit is located 
in its entirety within Indian Country, the notifications of this 
section must be sent to the appropriate Tribal authority. If any CCR 
unit is located in part within Indian Country, the notifications of 
this section must be sent both to the appropriate State Director and 
Tribal authority.
    (c) Combining notifications. Notifications may be combined as long 
as the deadline requirement for each notification is met.
    (d) Notification deadline after placement in operating record. 
Unless otherwise required in this section, the notifications specified 
in this section must be sent to the State Director and/or appropriate 
Tribal authority within 30 days of placing in the operating record the 
information required by Sec.  257.105.
* * * * *
    (f) * * *
    (24) Provide notification of the availability of the facility 
evaluation report part 1 as specified by Sec.  257.105(f)(25).
    (25) Provide notification of the availability of the facility 
evaluation report part 2 as specified by Sec.  257.105(f)(26).
* * * * *
    (k) Legacy CCR surface impoundments. In addition to the information 
specified in paragraphs (e) through (j) of this section, the owner or 
operator of a legacy CCR surface impoundment subject to this subpart 
must notify the State Director and/or appropriate Tribal authority when 
information has been placed in the operating record and on the owner or 
operator's publicly accessible internet site. The owner or operator 
must:
    (1) Provide notification of the availability of the applicability 
documentation as specified under Sec.  257.105(k)(1).
    (2) Provide notification of the availability of the applicability 
extension report as specified under Sec.  257.105(k)(2).
    (3) Provide notification of the availability of the notification as 
specified under Sec.  257.105(k)(3).
    (4) Provide notification of the availability of the intent to 
certify closure by removal certification as specified under Sec.  
257.105(k)(4).

0
24. Revise and republish Sec.  257.107 to read as follows:


Sec.  257.107  Publicly accessible internet site requirements.

    (a) CCR website requirement. Each owner or operator of a CCR unit 
subject to the requirements of this subpart must maintain a publicly 
accessible internet site (CCR website) containing the information 
specified in this section. The owner or operator's website must be 
titled ``CCR Rule Compliance Data and Information.'' The website must 
ensure that all information required to be posted is immediately 
available to anyone visiting the site, without requiring any 
prerequisite, such as registration or a requirement to submit a 
document request. All required information must be clearly identifiable 
and must be able to be immediately printed and downloaded by anyone 
accessing the site. If the owner/operator changes the web address 
(i.e., Uniform Resource Locator (URL)) at any point, they must notify 
EPA via the ``contact us'' form on EPA's CCR website and the state 
director within 14 days of making the change. The facility's CCR 
website must also have a ``contact us'' form or a specific email 
address posted on the website for the public to use to submit questions 
and issues relating to the availability of information on the website.
    (b) CCR website for multiple CCR units or combined websites for 
multiple regulatory programs.

[[Page 39119]]

    (1) An owner or operator of more than one CCR unit subject to the 
provisions of this subpart may comply with the requirements of this 
section by using the same internet site for multiple CCR units provided 
the CCR website clearly delineates information by the name or 
identification number of each unit.
    (2) An owner or operator may maintain one website combining the 
postings required under this subpart with the postings required by 
other regulatory programs (e.g., the ``ELG Rule Compliance Data and 
Information'' website required pursuant to Sec.  423.19 of this 
chapter), provided the postings required for each regulatory program 
are delineated under a separate heading on the website.
    (c) Document retention on a CCR website. Unless otherwise required 
in this section, the information required to be posted to the CCR 
website must be made available to the public for at least five years 
following the date on which the information was first posted to the CCR 
website.
    (d) Website posting deadline after placement in operating record. 
Unless otherwise required in this section, the information must be 
posted to the CCR website within 30 days of placing the pertinent 
information required by Sec.  257.105 in the operating record.
    (e) Location restrictions. The owner or operator of a CCR unit 
subject to this subpart must place each demonstration specified under 
Sec.  257.105(e) on the owner or operator's CCR website except each 
location restrictions demonstration must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) irrespective of the time requirement specified in paragraph 
(c) of this section.
    (f) Design criteria. The owner or operator of a CCR unit subject to 
this subpart must place the following information on the owner or 
operator's CCR website:
    (1) Within 60 days of commencing construction of a new unit, the 
design certification specified under Sec.  257.105(f)(1) or (3), except 
each certification must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (2) No later than the date of initial receipt of CCR by a new CCR 
unit, the construction certification specified under Sec.  
257.105(f)(1) or (3), except each certification must be posted for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g), or until the liner is removed irrespective of 
the time requirement specified in paragraph (c) of this section, 
whichever is later.
    (3) The documentation of liner type specified under Sec.  
257.105(f)(2), except each document must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g), or until the liner is removed irrespective of the 
time requirement specified in paragraph (c) of this section, whichever 
is later.
    (4) The initial and periodic hazard potential classification 
assessments specified under Sec.  257.105(f)(5), except only the two 
most recent hazard potential classification assessments must be posted 
for five years after completion of closure by removal in accordance 
with Sec.  257.102(c) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (5) The emergency action plan (EAP) specified under Sec.  
257.105(f)(6), except that only the most recent EAP must be maintained 
on the CCR website irrespective of the time requirement specified in 
paragraph (c) of this section.
    (6) Documentation prepared by the owner or operator recording the 
annual face-to-face meeting or exercise between representatives of the 
owner or operator of the CCR unit and the local emergency responders 
specified under Sec.  257.105(f)(7), except only the most recent 
documentation must be posted on the CCR website irrespective of the 
time requirement specified in paragraph (c) of this section.
    (7) Documentation prepared by the owner or operator recording any 
activation of the emergency action plan specified under Sec.  
257.105(f)(8); if no activation in the last five years, documentation 
that includes that information irrespective of the time requirement 
specified in paragraph (c) of this section.
    (8) The history of construction, and any revisions of it, specified 
under Sec.  257.105(f)(9), except the history of constructions, and any 
revisions of it, must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (9) The initial and periodic structural stability assessments 
specified under Sec.  257.105(f)(10), except only the two most recent 
structural stability assessments must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (10) The documentation detailing the corrective measures taken to 
remedy the deficiency or release specified under Sec.  257.105(f)(11), 
except each document must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (11) The initial and periodic safety factor assessments specified 
under Sec.  257.105(f)(12), except only the two most recent safety 
factor assessments must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (12) The design and construction plans, and any revisions of them, 
specified under Sec.  257.105(f)(13), except each plan must be posted 
for five years after completion of closure by removal in accordance 
with Sec.  257.102(c) or until completion of post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (13) The application and any supplemental materials submitted in 
support of the application specified under Sec.  257.105(f)(14), except 
each application must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (14) The alternative liner demonstration specified under Sec.  
257.105(f)(15).
    (15) The alternative liner demonstration specified under Sec.  
257.105(f)(16).

[[Page 39120]]

    (16) The documentation prepared for the preliminary demonstration 
specified under Sec.  257.105(f)(17).
    (17) The notification of an incomplete application specified under 
Sec.  257.105(f)(18).
    (18) The decision on the application specified under Sec.  
257.105(f)(19), except each decision must be posted for five years 
after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (c) of this section.
    (19) The final decision on the alternative liner demonstration 
specified under Sec.  257.105(f)(20).
    (20) The alternative source demonstration specified under Sec.  
257.105(f)(21).
    (21) The final decision on the alternative source demonstration 
specified under Sec.  257.105(f)(22).
    (22) The final decision on the trend analysis specified under Sec.  
257.105(f)(23).
    (23) The decision that the alternative source demonstration has 
been withdrawn specified under Sec.  257.105(f)(24).
    (24) The facility evaluation report part 1 as specified under Sec.  
257.105(f)(25), except each report must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (25) The facility evaluation report part 2 as specified under Sec.  
257.105(f)(26), except each report must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (g) Operating criteria. The owner or operator of a CCR unit subject 
to this subpart must place the following information on the owner or 
operator's CCR website:
    (1) The CCR fugitive dust control plan, or any subsequent amendment 
of the plan, specified under Sec.  257.105(g)(1) except that only the 
most recent plan must be maintained on the CCR website irrespective of 
the time requirement specified in paragraph (c) of this section until 
the last CCR unit at the facility completes closure by removal in 
accordance with Sec.  257.102(c) or completes post-closure care in 
accordance with Sec.  257.104(e) or (g) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (2) The annual CCR fugitive dust control report specified under 
Sec.  257.105(g)(2). Each report must be posted for the duration 
specified in paragraph (c) of this section, except that the final 
report must be posted for five years after completion of closure by 
removal in accordance with Sec.  257.102(c) or until completion of 
post-closure care in accordance with Sec.  257.104(e) or (g) 
irrespective of the time requirement specified in paragraph (c) of this 
section.
    (3) The initial and periodic run-on and run-off control system 
plans specified under Sec.  257.105(g)(3), except each plan must be 
posted for five years after completion of closure by removal in 
accordance with Sec.  257.102(c) or until completion of post-closure 
care in accordance with Sec.  257.104(e) or (g) irrespective of the 
time requirement specified in paragraph (c) of this section.
    (4) The initial and periodic inflow design flood control system 
plans specified under Sec.  257.105(g)(4), except each plan must be 
posted for five years after completion of closure by removal in 
accordance with Sec.  257.102(c) or until completion of post-closure 
care in accordance with Sec.  257.104(e) or (g) irrespective of the 
time requirement specified in paragraph (c) of this section.
    (5) The periodic inspection reports specified under Sec.  
257.105(g)(6). Each report must be posted for the duration specified in 
paragraph (c) of this section, except that the final report must be 
posted for five years after completion of closure by removal in 
accordance with Sec.  257.102(c) or until completion of post-closure 
care in accordance with Sec.  257.104(e) or (g) irrespective of the 
time requirement specified in paragraph (c) of this section.
    (6) The documentation detailing the corrective measures taken to 
remedy the deficiency or release specified under Sec.  257.105(g)(7). 
Each report must be posted for the duration specified in paragraph (c) 
of this section, except that the final documentation must be posted for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (7) The periodic inspection reports specified under Sec.  
257.105(g)(9). Each report must be posted for the duration specified in 
paragraph (c) of this section, except that the final report must be 
posted for five years after completion of closure by removal in 
accordance with Sec.  257.102(c) or until completion of post-closure 
care in accordance with Sec.  257.104(e) or (g) irrespective of the 
time requirement specified in paragraph (c) of this section.
    (h) Groundwater monitoring and corrective action. The owner or 
operator of a CCR unit subject to this subpart must place the following 
information on the owner or operator's CCR website:
    (1) The annual groundwater monitoring and corrective action report 
specified under Sec.  257.105(h)(1). Each report must be posted for the 
duration specified in paragraph (c) of this section, except that the 
final report must be posted for five years after completion of closure 
by removal in accordance with Sec.  257.102(c) or until completion of 
post-closure care in accordance with Sec.  257.104(e) or (g) 
irrespective of the time requirement specified in paragraph (c) of this 
section.
    (2) The groundwater monitoring system certification specified under 
Sec.  257.105(h)(3), except each certification must be posted for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (c) of this section.
    (3) The selection of a statistical method certification specified 
under Sec.  257.105(h)(4), except each certification must be posted for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (4) The notification that an assessment monitoring programs has 
been established specified under Sec.  257.105(h)(5).
    (5) The notification that the CCR unit is returning to a detection 
monitoring program specified under Sec.  257.105(h)(7).
    (6) The notification that one or more constituents in appendix IV 
to this part have been detected at statistically significant levels 
above the groundwater protection standard and the notifications to land 
owners specified under Sec.  257.105(h)(8).
    (7) The notification that an assessment of corrective measures has 
been initiated specified under Sec.  257.105(h)(9).
    (8) The assessment of corrective measures specified under Sec.  
257.105(h)(10), except each assessment must be posted for five years

[[Page 39121]]

after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (c) of this section.
    (9) The semiannual reports describing the progress in selecting and 
designing remedy and the selection of remedy report specified under 
Sec.  257.105(h)(12), except that the selection of the remedy report 
must be maintained until the remedy has been completed.
    (10) The notification that the remedy has been completed specified 
under Sec.  257.105(h)(13), except each notification must be posted for 
five years after completion of the remedy selected pursuant to in Sec.  
257.97 irrespective of the time requirement specified in paragraph (c) 
of this section.
    (11) The demonstration supporting the suspension of groundwater 
monitoring requirements specified under Sec.  257.105(h)(14), except 
each demonstration must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (i) Closure and post-closure care. The owner or operator of a CCR 
unit subject to this subpart must place the following information on 
the owner or operator's CCR website:
    (1) The notification of intent to initiate closure of the CCR unit 
specified under Sec.  257.105(i)(1).
    (2) The annual progress reports of closure implementation specified 
under Sec.  257.105(i)(2).
    (3) The notification of closure completion specified under Sec.  
257.105(i)(3).
    (4) The written closure plan, and any amendment of the plan, 
specified under Sec.  257.105(i)(4), except that only the most recent 
closure plan must be posted on the CCR website irrespective of the time 
requirement specified in paragraph (c) of this section and each closure 
plan must be maintained for five years after completion of closure by 
removal in accordance with Sec.  257.102(c)(1) or completion of post-
closure care in accordance with Sec.  257.104(e) irrespective of the 
time requirement specified in paragraph (c) of this section.
    (5) The demonstration(s) for a time extension for initiating 
closure specified under Sec.  257.105(i)(5), except each demonstration 
must be posted until notice of completion of closure is placed in the 
operating record in accordance with Sec.  257.102(h) irrespective of 
the time requirement specified in paragraph (c) of this section.
    (6) The demonstration(s) for a time extension for completing 
closure specified under Sec.  257.105(i)(6), except each demonstration 
must be posted for five years after completion of closure in accordance 
with Sec.  257.102(c) or (d) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (7) The notification of intent to close a CCR unit specified under 
Sec.  257.105(i)(7), except each notification must be posted for five 
years after completion of closure in accordance with Sec.  257.102(c) 
or (d) irrespective of the time requirement specified in paragraph (c) 
of this section.
    (8) The notification of completion of closure of a CCR unit 
specified under Sec.  257.105(i)(8), except each notification must be 
posted for five years after completion of closure by removal in 
accordance with Sec.  257.102(c)(1) or completion of post-closure care 
in accordance with Sec.  257.104(e) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (9) The notification recording a notation on the deed as required 
by Sec.  257.105(i)(9), except each notification must be posted for 
five years after completion of post-closure care in accordance with 
Sec.  257.104(e) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (10) The notification of intent to comply with the alternative 
closure requirements as required by Sec.  257.105(i)(10), except the 
notification must be posted for five years after completion of closure 
in accordance with Sec.  257.102(c) or (d) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (11) The annual progress reports under the alternative closure 
requirements as required by Sec.  257.105(i)(11), except the 
notification must be posted for five years after completion of closure 
in accordance with Sec.  257.102(c) or (d) irrespective of the time 
requirement specified in paragraph (c) of this section.
    (12) The written post-closure plan, and any amendment of the plan, 
specified under Sec.  257.105(i)(12), except that only the most recent 
post-closure plan must be maintained for five years after completion of 
post-closure care in accordance with Sec.  257.104(e) irrespective of 
the time requirement specified in paragraph (c) of this section.
    (13) The notification of completion of post-closure care specified 
under Sec.  257.105(i)(13), except that only the most recent post-
closure plan must be maintained for five years after completion of 
post-closure care in accordance with Sec.  257.104(e) irrespective of 
the time requirement specified in paragraph (c) of this section.
    (14) The notification of intent to comply with the site-specific 
alternative to initiation of closure due to development of alternative 
capacity infeasible as specified under Sec.  257.105(i)(14), except 
each notification must be posted for five years after completion of 
closure by removal in accordance with Sec.  257.102(c)(1) or completion 
of post-closure care in accordance with Sec.  257.104(e) irrespective 
of the time requirement specified in paragraph (c) of this section.
    (15) The approved or denied demonstration for the site-specific 
alternative to initiation of closure due to development of alternative 
capacity infeasible as required by as specified under Sec.  
257.105(i)(15), except each approval or denial must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (16) The notification for requesting additional time to the 
alternative cease receipt of waste deadline as required by Sec.  
257.105(i)(16), except the notification must be maintained for five 
years after completion of closure by removal in accordance with Sec.  
257.102(c) or until completion of post-closure care in accordance with 
Sec.  257.104(e) or (g) irrespective of the time requirement specified 
in paragraph (c) of this section.
    (17) The semi-annual progress reports for the site-specific 
alternative to initiation of closure due to development of alternative 
capacity infeasible as specified under Sec.  257.105(i)(17), except the 
progress report must be maintained for five years after completion of 
closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (18) The notification of intent to comply with the site-specific 
alternative to initiation of closure due to permanent cessation of a 
coal-fired boiler(s) by a date certain as specified under Sec.  
257.105(i)(18), except the notification

[[Page 39122]]

must be maintained for five years after completion of closure by 
removal in accordance with Sec.  257.102(c) or until completion of 
post-closure care in accordance with Sec.  257.104(e) or (g) 
irrespective of the time requirement specified in paragraph (c) of this 
section.
    (19) The approved or denied demonstration for the site-specific 
alternative to initiation of closure due to permanent cessation of a 
coal-fired boiler(s) by a date certain as required by Sec.  
257.105(i)(19), except the approval or denial must be maintained for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (20) The annual progress report for the site-specific alternative 
to initiation of closure due to permanent cessation of a coal-fired 
boiler(s) by a date certain as required by Sec.  257.105(i)(20), except 
the progress reports must be maintained for five years after completion 
of closure by removal in accordance with Sec.  257.102(c) or until 
completion of post-closure care in accordance with Sec.  257.104(e) or 
(g) irrespective of the time requirement specified in paragraph (c) of 
this section.
    (j) Retrofit criteria. The owner or operator of a CCR unit subject 
to this subpart must place the following information on the owner or 
operator's CCR website:
    (1) The written retrofit plan, and any amendment of the plan, 
specified under Sec.  257.105(j)(1).
    (2) The notification of intent to comply with the alternative 
retrofit requirements as required by Sec.  257.105(j)(2).
    (3) The annual progress reports under the alternative retrofit 
requirements as required by Sec.  257.105(j)(3).
    (4) The demonstration(s) for a time extension for completing 
retrofit activities specified under Sec.  257.105(j)(4).
    (5) The notification of intent to retrofit a CCR unit specified 
under Sec.  257.105(j)(5).
    (6) The notification of completion of retrofit activities specified 
under Sec.  257.105(j)(6).
    (k) Legacy CCR surface impoundments. In addition to the information 
specified in paragraphs (e) through (j) of this section, the owner or 
operator of a legacy CCR surface impoundment subject to this subpart 
must place the following information on the owner or operator's CCR 
website:
    (1) The applicability report as specified under Sec.  
257.105(k)(1), except each report must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (2) The applicability extension reports as specified under Sec.  
257.105(k)(2), except each report must be posted for five years after 
completion of closure by removal in accordance with Sec.  257.102(c) or 
until completion of post-closure care in accordance with Sec.  
257.104(e) or (g) irrespective of the time requirement specified in 
paragraph (c) of this section.
    (3) The notification of field investigation conclusion as specified 
under Sec.  257.105(k)(3), except each notification must be posted for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.
    (4) The notification of intent to certify closure as specified 
under Sec.  257.105(k)(4), except each notification must be posted for 
five years after completion of closure by removal in accordance with 
Sec.  257.102(c) or until completion of post-closure care in accordance 
with Sec.  257.104(e) or (g) irrespective of the time requirement 
specified in paragraph (c) of this section.

[FR Doc. 2024-09157 Filed 5-7-24; 8:45 am]
 BILLING CODE 6560-50-P