[Federal Register Volume 87, Number 88 (Friday, May 6, 2022)]
[Rules and Regulations]
[Pages 27002-27024]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-09658]



[[Page 27002]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2020-0560; FRL-7546-02-OAR]
RIN 2060-AU59


National Emission Standards for Hazardous Air Pollutants: Mercury 
Cell Chlor-Alkali Plants Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action finalizes the residual risk and technology review 
(RTR) conducted for the Mercury Cell Chlor-Alkali Plants source 
category regulated under national emission standards for hazardous air 
pollutants (NESHAP). In addition, this action finalizes the beyond-the-
floor determination that EPA performed in response to a petition for 
reconsideration of the 2003 NESHAP. These final amendments prohibit 
mercury emissions from existing mercury cell chlor-alkali plants based 
on the results of our technology review and our beyond-the-floor 
maximum achievable control technology (MACT) determination. The 
compliance date for this requirement is three years. Since mercury 
emissions will be eliminated as a result of the final rule standards, 
any adverse health or environmental effects from mercury emissions from 
the source category will also be eliminated in that three-year time 
frame. Furthermore, the EPA is finalizing work practice standards and 
instrumental monitoring of mercury to minimize fugitive mercury 
emissions from the cell rooms during the period of time before 
emissions are eventually eliminated. In addition, the EPA is finalizing 
work practice standards to minimize fugitive chlorine emissions from 
mercury cell chlor-alkali plants, which were not previously regulated 
under the NESHAP. The EPA is also finalizing revisions related to 
emissions during periods of startup, shutdown, and malfunction (SSM) 
and amendments to correct a few minor errors in compliance provisions 
in the 2003 rule.

DATES: This final rule is effective on May 6, 2022.

ADDRESSES: The U.S. Environmental Protection Agency (EPA) has 
established a docket for this action under Docket ID No. EPA-HQ-OAR-
2020-0560. All documents in the docket are listed on the https://www.regulations.gov/ website. Although listed, some information is not 
publicly available, e.g., Confidential Business Information 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 https://www.regulations.gov/, or in hard copy at the EPA Docket Center, WJC 
West Building, Room Number 3334, 1301 Constitution Ave. NW, Washington, 
DC. The Public Reading Room hours of operation are 8:30 a.m. to 4:30 
p.m. Eastern Standard Time (EST), Monday through Friday. The telephone 
number for the Public Reading Room is (202) 566-1744, and the telephone 
number for the EPA Docket Center is (202) 566-1742. Hand Deliveries and 
couriers may be received by scheduled appointment only. For further 
information and updates on EPA Docket Center services and the current 
status, please visit us online at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: For questions about this final action, 
contact Phil Mulrine, Sector Policies and Programs Division (D243-02), 
Office of Air Quality Planning and Standards, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711; 
telephone number: (919) 541-5289; fax number: (919) 541-4991; and email 
address: [email protected]. For specific information regarding the 
risk modeling methodology, contact James Hirtz, Health and 
Environmental Impacts Division, Office of Air Quality Planning and 
Standards, U.S. Environmental Protection Agency, Research Triangle 
Park, North Carolina 27711; telephone number: (919) 541-0881; fax 
number: (919) 541-0840; and email address: [email protected].

SUPPLEMENTARY INFORMATION: 
    Preamble acronyms and abbreviations. We use multiple acronyms and 
terms in this preamble. Throughout this document wherever ``we,'' 
``us,'' or ``our'' is used, it is intended to refer to the EPA. While 
this list may not be exhaustive, to ease the reading of this preamble 
and for reference purposes, the EPA defines the following terms and 
acronyms here:

AEGL acute exposure guideline level two
CAA Clean Air Act
CFR Code of Federal Regulations
Cl2 Chlorine
CRA Congressional Review Act
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
HAP hazardous air pollutants(s)
HCl hydrochloric acid
Hg mercury
HI hazard index
HQ hazard quotient
MACT maximum achievable control technology
MATS Mercury and Air Toxics Standards
NAIC North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
NTTAA National Technology Transfer and Advancement Act
NOCS Notification of Compliance Status report
NRDC Natural Resources Defense Council
OMB Office of Management and Budget
PB-HAP HAPs known to be persistent and bioaccumulative in the 
environment
PDF portable document format
PM particulate matter
ppm parts per million
ppmv parts per million by volume
PRA Paperwork Reduction Act
REL reference exposure limit
RTR risk and technology review
SSM startup, shutdown, and malfunction
SV screening value
TOSHI target organ-specific hazard index
tpy tons per year
UMRA Unfunded Mandates Reform Act

    Background information. On January 8, 2021, the EPA proposed 
revisions to the 2003 Mercury Cell Chlor-Alkali Plants NESHAP, 40 CFR 
part 63, subpart IIIII, based on our RTR and MACT beyond-the-floor 
analyses (86 FR 1362, January 8, 2021). In this action, we are 
finalizing decisions and revisions for the rule. We summarize the 
comments we timely received regarding the proposed rule and provide our 
responses in this preamble. A ``track changes'' version of the 
regulatory language that incorporates the changes in this action is 
available in the docket.
    Organization of this document. The information in this preamble is 
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
    C. Judicial Review and Administrative Reconsideration
II. Background
    A. What is the statutory authority for this action?
    B. What is the Mercury Cell Chlor-Alkali Plants source category 
and how does the NESHAP regulate HAP emissions from the source 
category?
    C. What changes did we propose for the Mercury Cell Chlor-Alkali 
Plants source category in our January 8, 2021 proposal?
III. What is included in this final rule?
    A. What are the final rule amendments based on the risk review 
for the Mercury Cell Chlor-Alkali Plants source category?
    B. What are the final rule amendments related to a non-mercury 
option for the Mercury Cell Chlor-Alkali Plants Source Category 
pursuant to CAA sections 112(d)(2), (3), and (6)?
    C. What are the final rule amendments based on the technology 
review for the

[[Page 27003]]

Mercury Cell Chlor-Alkali Plants source category?
    D. What are the final rule amendments pursuant to sections 
112(d)(2) and (3) and (h) for the Mercury Cell Chlor-Alkali Plants 
source category?
    E. What are the final rule amendments addressing emissions 
during periods of startup, shutdown, and malfunction?
    F. What are the effective and compliance dates of the standards?
IV. What is the rationale for our final decisions and amendments for 
the Mercury Cell Chlor-Alkali Plants source category?
    A. Residual Risk Review for the Mercury Cell Chlor-Alkali Plants 
Source Category
    B. Non-Mercury Option for the Mercury Cell Chlor-Alkali Plants 
Source Category
    C. Technology Review for the Mercury Cell Chlor-Alkali Plants 
Source Category
    D. Amendments Pursuant to Sections 112(d)(2) and (3) and (h) for 
the Mercury Cell Chlor-Alkali Plants Source Category
    E. Amendments Addressing Emissions During Periods of Startup, 
Shutdown, and Malfunction and Other Topics
    F. Public Notice and Comments
V. Summary of Cost, Environmental, and Economic Impacts and 
Additional Analyses Conducted
    A. What are the affected facilities?
    B. What are the air quality and other environmental impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we 
conduct?
VI. Statutory and Executive Order Reviews
    A. Executive Orders 12866: Regulatory Planning and Review and 
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act (CRA)

I. General Information

A. Does this action apply to me?

    Regulated entities. Categories and entities potentially regulated 
by this action are shown in Table 1 of this preamble.

 Table 1--NESHAP and Industrial Source Categories Affected by This Final
                                 Action
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                                                               NAICS \1\
                 NESHAP and source category                      code
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Mercury Cell Chlor-Alkali Plants............................      325180
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\1\ North America Industry Classification System.

    Table 1 of this preamble is not intended to be exhaustive, but 
rather to provide a guide for readers regarding entities likely to be 
affected by the final action for the source category listed. To 
determine whether your facility is affected, you should examine the 
applicability criteria in the appropriate NESHAP. If you have any 
questions regarding the applicability of any aspect of this NESHAP, 
please contact the appropriate person listed in the preceding FOR 
FURTHER INFORMATION CONTACT section of this preamble.

B. Where can I get a copy of this document and other related 
information?

    In addition to being available in the docket, an electronic copy of 
this final action will also be available on the internet. Following 
signature by the EPA Administrator, the EPA will post a copy of this 
final action at: https://www.epa.gov/stationary-sources-air-pollution/mercury-cell-chloralkali-plants-national-emissions-standards. Following 
publication in the Federal Register, the EPA will post the Federal 
Register version and key technical documents at this same website.
    Additional information is available on the RTR website at https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous. This information 
includes an overview of the RTR program and links to project websites 
for the RTR source categories.

C. Judicial Review and Administrative Reconsideration

    Under Clean Air Act (CAA) section 307(b)(1), judicial review of 
this final action is available only by filing a petition for review in 
the United States Court of Appeals for the District of Columbia Circuit 
(the Court) by July 5, 2022. Under CAA section 307(b)(2), the 
requirements established by this final rule may not be challenged 
separately in any civil or criminal proceedings brought by the EPA to 
enforce the requirements.
    Section 307(d)(7)(B) of the CAA further provides that only an 
objection to a rule or procedure which was raised with reasonable 
specificity during the period for public comment (including any public 
hearing) may be raised during judicial review. This section also 
provides a mechanism for the EPA to reconsider the rule if the person 
raising an objection can demonstrate to the Administrator that it was 
impracticable to raise such objection within the period for public 
comment or if the grounds for such objection arose after the period for 
public comment (but within the time specified for judicial review) and 
if such objection is of central relevance to the outcome of the rule. 
Any person seeking to make such a demonstration should submit a 
Petition for Reconsideration to the Office of the Administrator, U.S. 
EPA, Room 3000, WJC South Building, 1200 Pennsylvania Ave. NW, 
Washington, DC 20460, with a copy to both the person(s) listed in the 
preceding FOR FURTHER INFORMATION CONTACT section, and the Associate 
General Counsel for the Air and Radiation Law Office, Office of General 
Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW, 
Washington, DC 20460.

II. Background

A. What is the statutory authority for this action?

    Section 112 of the CAA establishes a two-stage regulatory process 
to address emissions of hazardous air pollutants (HAP) from stationary 
sources. In the first stage, we must identify categories of sources 
emitting one or more of the HAP listed in CAA section 112(b) and then 
promulgate technology-based NESHAP for those sources. ``Major sources'' 
are those that emit, or have the potential to emit, any single HAP at a 
rate of 10 tons per year (tpy) or more, or 25 tpy or more of any 
combination of HAP. For major sources, these standards are commonly 
referred to as MACT standards and must reflect the maximum degree of 
emission reductions of HAP achievable (after considering cost, energy 
requirements, and non-air quality health and environmental impacts). In 
developing MACT standards, CAA section 112(d)(2) directs the EPA to 
consider the application of measures, processes, methods, systems, or 
techniques, including, but not limited to, those that reduce the volume 
of or eliminate HAP emissions through process changes, substitution of 
materials, or other modifications; enclose systems or processes to 
eliminate emissions; collect, capture, or treat HAP when released from 
a process, stack, storage, or fugitive emissions point; are design, 
equipment, work

[[Page 27004]]

practice, or operational standards; or any combination of the above.
    For these MACT standards, the statute specifies certain minimum 
stringency requirements, which are referred to as MACT floor 
requirements, and which may not be based on cost considerations. See 
CAA section 112(d)(3). For new sources, the MACT floor cannot be less 
stringent than the emission control achieved in practice by the best-
controlled similar source. The MACT standards for existing sources can 
be less stringent than floors for new sources, but they cannot be less 
stringent than the average emission limitation achieved by the best-
performing 12 percent of existing sources in the category or 
subcategory (or the best-performing five sources for categories or 
subcategories with fewer than 30 sources). In developing MACT 
standards, we must also consider control options that are more 
stringent than the floor under CAA section 112(d)(2). We may establish 
standards more stringent than the floor, based on the consideration of 
the cost of achieving the emissions reductions, any non-air quality 
health and environmental impacts, and energy requirements.
    In the second stage of the regulatory process, the CAA requires the 
EPA to undertake two different analyses, which we refer to as the 
technology review and the residual risk review. Under the technology 
review, we must review the technology-based standards and revise them 
``as necessary (taking into account developments in practices, 
processes, and control technologies)'' no less frequently than every 8 
years, pursuant to CAA section 112(d)(6). In conducting this review, 
the EPA is not required to recalculate the MACT floors that were 
established in earlier rulemakings. Natural Resources Defense Council 
v. EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008) (NRDC). Association of 
Battery Recyclers, Inc. v. EPA, 716 F.3d 667 (D.C. Cir. 2013). The EPA 
may consider cost in deciding whether to revise the standards pursuant 
to CAA section 112(d)(6). The EPA is required to address regulatory 
gaps, such as missing standards for listed air toxics known to be 
emitted from the source category, and any new MACT standards must be 
established under CAA sections 112(d)(2) and (3), or, in specific 
circumstances, CAA sections 112(d)(4) or (h). Louisiana Environmental 
Action Network v. EPA, 955 F.3d 1088 (D.C. Cir. 2020) (LEAN). Under the 
residual risk review, we must evaluate the risk to public health 
remaining after application of the technology-based standards and 
revise the standards, if necessary, to provide an ample margin of 
safety to protect public health or to prevent, taking into 
consideration costs, energy, safety, and other relevant factors, an 
adverse environmental effect. The residual risk review is required 
within 8 years after promulgation of the technology-based standards, 
pursuant to CAA section 112(f). In conducting the residual risk review, 
if the EPA determines that the current standards provide an ample 
margin of safety to protect public health, it is not necessary to 
revise the MACT standards pursuant to CAA section 112(f).\1\ For more 
information on the statutory authority for this rule, see https://www.federalregister.gov/documents/2021/01/08/2021-00174/national-emission-standards-for-hazardous-air-pollutants-mercury-cell-chlor-alkali-plants-residual.
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    \1\ The Court has affirmed this approach of implementing CAA 
section 112(f)(2)(A): NRDC, 529 F.3d at 1083 (``If EPA determines 
that the existing technology-based standards provide an 'ample 
margin of safety,' then the Agency is free to readopt those 
standards during the residual risk rulemaking.'').
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B. What is the Mercury Cell Chlor-Alkali Plants source category and how 
does the NESHAP regulate HAP emissions from the source category?

    The EPA promulgated the Mercury Cell Chlor-Alkali Plants NESHAP on 
December 19, 2003 (68 FR 70904). The standards are codified at 40 CFR 
part 63, subpart IIIII. The mercury cell chlor-alkali industry consists 
of facilities that use mercury cells to manufacture product chlorine, 
product caustic, and by-product hydrogen via an electrolytic process. 
The source category covered by these MACT standards currently includes 
one operating facility, Westlake located in West Virginia.
    Subpart IIIII covers both major and area sources. The single 
remaining operational mercury cell-chlor-alkali plant in the category 
is located at a major source site. In addition to subpart IIII, 
processes at this major source site are subject to subparts ZZZZ 
(Reciprocating Internal Combustion Engine NESHAP) and DDDDD 
(Industrial/Commercial/Institutional Boilers and Process Heaters). The 
mercury cell chlor-alkali NESHAP includes standards for mercury 
emissions from two types of affected sources at plant sites where 
chlorine and caustic are produced in mercury cells: Mercury cell chlor-
alkali production facility affected sources and mercury recovery 
facility affected sources. The 2003 rule prohibited mercury emissions 
from new and reconstructed mercury cell chlor-alkali production 
affected sources. 40 CFR 63.8190(a)(1). For existing mercury cell 
chlor-alkali production affected sources, the 2003 standards included 
emission limitations for mercury emissions from process vents 
(including emissions from end-box ventilation systems and hydrogen 
systems) and work practices for fugitive mercury emissions from the 
cell room. 40 CFR 63.8190(a)(2), 63.8192(a) through (f).
    For new, reconstructed, and existing mercury recovery facilities, 
the 2003 NESHAP included emission limitations for mercury emissions 
from oven type thermal recovery unit vents and non-oven type thermal 
recovery unit vents. 40 CFR 63.8190(a)(3). Note that the single 
remaining operational facility does not operate a mercury recovery 
facility, so there are no operating mercury recovery facilities subject 
to subpart IIIII.
    The 2003 rule did not promulgate standards for chlorine 
(Cl2) or hydrochloric acid (HCl), citing the authority of 
section 112(d)(4) of the CAA (68 FR 70906). In its 2003 action (68 FR 
70904), the EPA promulgated the initial Mercury Cell Chlor-Alkali 
Plants NESHAP pursuant to CAA section 112(d)(2) and (3) and added the 
source category to the EPA's Source Category List under CAA sections 
112(c)(1), as well as under (c)(3), (c)(6) and (k)(3)(B), in each case 
because of the mercury emissions.
    Following promulgation of the 2003 Mercury Cell Chlor-Alkali Plants 
NESHAP, the EPA received a petition to reconsider several aspects of 
the rule from the Natural Resources Defense Council (NRDC). NRDC also 
filed a petition for judicial review of the rule in the U.S. Court of 
Appeals for the District of Columbia Circuit. In a letter dated April 
8, 2004, the EPA granted NRDC's petition for reconsideration and on 
July 20, 2004, the court placed the petition for judicial review in 
abeyance pending the EPA's action on reconsideration.
    The EPA issued proposed revisions to the 2003 rule on June 11, 2008 
(73 FR 33258) and on March 14, 2011 (76 FR 13852), to respond to the 
reconsideration petition. This final action completes EPA's rulemaking 
following those two proposals and the third action proposed on January 
8, 2021 (86 FR 1362), and completes the EPA's action in response to the 
2004 petition for reconsideration of the 2003 rule.

[[Page 27005]]

C. What changes did we propose for the Mercury Cell Chlor-Alkali Plants 
source category in our January 8, 2021, proposal?

    On January 8, 2021, the EPA published a proposed rule in the 
Federal Register for the Mercury Cell Chlor-Alkali Plants NESHAP, 40 
CFR part 63, subpart IIIII, that took into consideration the RTR 
analyses and the MACT beyond-the-floor analysis. In the proposed rule, 
we proposed: (1) The determination that risks due to emissions of HAP 
are acceptable from the Mercury Cell Chlor-Alkali Plants source 
category and that the 2003 NESHAP provides an ample margin of safety to 
protect public health; (2) to amend the requirements for cell room 
fugitive mercury emissions to require work practice standards for the 
cell rooms plus instrumental monitoring of cell room fugitive mercury 
emissions under the technology review; (3) work practice standards for 
fugitive chlorine emissions from mercury cell chlor-alkali plants, 
which were not previously regulated under the NESHAP; (4) revisions 
related to emissions during periods of startup, shutdown and 
malfunction (SSM), which had also been addressed in the 2011 proposed 
rule; (5) provisions for electronic submission of performance test 
results, compliance reports, and Notification of Compliance Status 
(NOCS) reports; and (6) amendments to correct minor errors and improve 
the compliance provisions of the rule, which had also been addressed in 
the 2008 and 2011 proposals.
    With regard to our technology review and an overdue beyond-the-
floor determination, as explained in the January 2021 document (86 FR 
1362, January 8, 2021), we evaluated two options: (1) Improved cell 
room mercury monitoring and work practices to minimize emissions; and 
(2) the elimination of Hg emissions by requiring the conversion to a 
non-Hg technology.
    Based on this evaluation, we proposed option 1, as mentioned above, 
however we also described option 2 (mercury elimination) in detail in 
the January 2021 notice and solicited comments. Specifically, we 
explained that based on consideration of the updated costs and cost 
effectiveness and uncertainties, and given the passage of time, and the 
fact that the cost-effectiveness data and analysis done in 2011 were 
based on two facilities that are no longer operating, we questioned at 
that time whether those 2011 analyses would still be transferable to 
the one remaining operating facility. Consequently, we did not propose 
to require the elimination of mercury in the January 2021 document. 
However, we solicited comments, data, and other information regarding 
this proposed decision, including data and information regarding the 
capital and annual costs, cost effectiveness, non-air impacts, and 
other relevant information that would be relevant for the remaining 
facility regarding whether the NESHAP should include a zero-mercury 
standard as a beyond-the-floor MACT standard. We also stated that we 
intend to consider any such submitted data and information, in addition 
to the data and information contained in the records for the 2008 and 
2011 proposals and in the 2021 proposal, in reaching final conclusions 
regarding a zero-mercury standard (see 86 FR 1362, January 8, 2021).

III. What is included in this final rule?

    This action finalizes the EPA's determinations pursuant to the RTR 
and MACT provisions of CAA section 112 for the Mercury Cell Chlor-
Alkali Plants source category and amends the Mercury Cell Chlor-Alkali 
Plants NESHAP based on those determinations.

A. What are the final rule amendments based on the risk review for the 
Mercury Cell Chlor-Alkali Plants source category?

    No changes to the Mercury Cell Chlor-Alkali Plants NESHAP are being 
promulgated to meet the requirements of CAA section 112(f). Under this 
action, for purposes of section 112(f), we are finalizing the risk 
assessments and our determination that the risks from the Mercury Cell 
Chlor-Alkali Plants source category are acceptable, the 2003 standards 
provide an ample margin of safety to protect public health, and more 
stringent standards are not necessary to prevent an adverse 
environmental effect.

B. What are the final rule amendments related to a non-mercury option 
for the Mercury Cell Chlor-Alkali Plants Source Category pursuant to 
sections 112(d)(2), (3), and (6)?

    To satisfy the requirements of CAA sections 112(d)(2), (d)(3), and 
(6), including to respond to the petition for reconsideration of the 
2003 rule by completing our MACT beyond-the-floor analysis, we are 
revising the MACT standards to prohibit mercury emissions from existing 
mercury cell chlor-alkali plants. Specifically, these amendments 
prohibit mercury emissions from existing mercury chlor-alkali 
production facility affected sources. This makes the mercury standard 
for existing sources the same as the standard for new and reconstructed 
sources that has been in the NESHAP since 2003. Since we conclude that 
it is improbable that a mercury cell chlor-alkali plant can be operated 
without mercury emissions, we expect this revision will effectively 
require the lone remaining mercury cell chlor-alkali plant in operation 
in the U.S. to cease production of chlorine with their single mercury 
cell production unit. We anticipate the facility will continue to 
produce chlorine through its other, higher-volume non-mercury chlorine 
production units located at the Westlake facility and may convert the 
mercury cell unit to a membrane cell or other non-mercury chlorine 
production process. There are no mercury recovery facilities still in 
operation in the U.S. This final rule provides a three-year period to 
comply with the requirement to eliminate mercury emissions from the 
single remaining existing affected source. To demonstrate compliance, 
the owner or operator will need to submit a notification certifying 
that all mercury emissions have been eliminated permanently no later 
than 120 days after the compliance date.

C. What are the final rule amendments based on the technology review 
for the Mercury Cell Chlor-Alkali Plants source category?

    We determined that there are developments in practices, processes, 
and control technologies that warrant revisions to the MACT standards 
for this source category. As noted above, we are revising the MACT 
standards to include a prohibition of mercury emissions, which is based 
on both a section 112(d)(6) technology review and our beyond-the-floor 
review under section 112(d)(2) and (3) in response to NRDC's 2004 
petition for reconsideration. Also based on the section 112(d)(6) 
technology review and in response to NRDC's 2004 petition, we are 
amending the requirements for cell room fugitive mercury emissions to 
require work practice standards for the cell rooms along with 
instrumental monitoring of cell room fugitive mercury emissions during 
the period of time before emissions are eventually eliminated. In 
addition, under the technology review, we identified a regulatory gap, 
and as discussed below, we are establishing new standards under CAA 
section 112(h).

[[Page 27006]]

D. What are the final rule amendments pursuant to sections 112(d)(2) 
and (3) and (h) for the Mercury Cell Chlor-Alkali Plants source 
category?

    In addition to the requirements for mercury described above, we are 
also finalizing amendments pursuant to section 112(h) for chlorine 
emissions, similar to the standards we proposed in January 2021 (86 FR 
1362), that require implementation of work practices to minimize 
chlorine emissions from the mercury cell chlor-alkali processes. 
Further details regarding these work practice standards are described 
in section IV.D of this document.

E. What are the final rule amendments addressing emissions during 
periods of startup, shutdown, and malfunction?

    We are finalizing amendments related to provisions that apply 
during periods of SSM that the EPA proposed on January 8, 2021. Further 
details are provided in section IV.E of this document.

F. What are the effective and compliance dates of the standards?

    The revisions to the MACT standards being promulgated in this 
action are effective on May 6, 2022. The compliance date for existing 
mercury cell chlor-alkali plants to eliminate mercury emissions is May 
6, 2025.
    These final amendments will essentially require that the single 
remaining operating mercury cell chlor-alkali facility either convert 
its one mercury cell unit to a non-mercury technology (its other units 
are already using non-mercury technology) or close that mercury cell 
unit and thereafter rely solely on its other non-mercury units for 
chlorine production. Either of these options will require significant 
time for the company to reach a decision and to develop and implement a 
plan of action. For example, it is expected that it could take between 
six months and one year to develop an engineering design and plan for 
conversion. The facility would then need to solicit bids for the 
conversion, which could take up to six months. Construction could then 
take up to two years. In addition, arrangements will need to be made to 
dismantle the mercury cell facility, to store the elemental mercury 
removed from the cells and to dispose of the mercury-contaminated 
wastes. The most recent conversion in the U.S. was the facility in 
Ashtabula, Ohio. This Ashtabula facility was, like the West Virginia, 
facility, one of the smaller capacity mercury cell units in the U.S. 
(less than 75,000 tons of chlorine per year). It was also of similar 
age (Ashtabula constructed in 1963 and West Virginia in 1958) and was 
located in a neighboring state. The company announced the plans to 
convert their mercury cell process to membrane cells in 2014. They 
broke ground in 2017 and the conversion was complete in 2020. In 
conclusion, six years elapsed between the time the decision to convert 
was made and the conversion was completed, which included three full 
years for the dismantling/construction. Therefore, we conclude that the 
full three-year compliance period allowed by section 112(i)(3) of the 
CAA to meet new or revised emission standards is warranted. Moreover, 
as discussed further below, this period will provide ample time for the 
United States, via the elimination of mercury emissions from the plant, 
to meet its obligations to eliminate mercury emissions from this source 
category under the international treaty known as the Minamata 
Convention.
    For existing sources, in 2021, we proposed two changes to the work 
practice standards. One of these changes was the requirement to operate 
a cell-room mercury monitoring program in addition to mercury work 
practices. This change was proposed in both 2008 and 2011. The second 
proposed change is a program to require work practices to reduce 
fugitive chlorine emissions. While these proposed work practice 
standards were based on the practices in place at the single facility 
in the source category, they will require some modifications to the 
procedures currently employed at the facility. Specifically, they will 
need to develop and implement a recordkeeping system to record and 
maintain the records required for the mercury cell and fugitive 
chlorine work practices and to incorporate the required material in the 
requisite reports. As proposed, we are providing 180 days for the 
facility to modify their current procedures. Therefore, the mercury and 
chlorine work practice standards being promulgated in this action 
require compliance on November 2, 2022.
    We also proposed in January 2021, a change to the SSM requirements 
to remove the exemption from the requirements to meet the standards 
during SSM periods and to remove the requirement to develop and 
implement an SSM plan. This change was also proposed in 2008 and 2011. 
Our experience with similar industries shows that this sort of 
regulated facility generally requires a time period of 6 months to read 
and understand the amended rule requirements; to evaluate their 
operations to ensure that they can meet the standards during periods of 
startup and shutdown as defined in the rule and make any necessary 
adjustments; and to update their operation, maintenance, and monitoring 
plans to reflect the revised requirements. As proposed, we are 
providing 180 days for the facility to comply with the revised SSM 
requirements. As such, these revisions require compliance by November 
2, 2022.

IV. What is the rationale for our final decisions and amendments for 
the Mercury Cell Chlor-Alkali Plants source category?

    For each issue, this section provides a description of what we 
addressed in the proposed rules for the source category and what we are 
finalizing for the issue, the EPA's rationale for the final decisions 
and amendments, and the comments and responses.

A. Residual Risk Review for the Mercury Cell Chlor-Alkali Plants Source 
Category

1. What did we propose pursuant to CAA Section 112(f) for the Mercury 
Cell Chlor-Alkali Plants source category?
    We proposed that health risks due to emissions of HAP from the 
Mercury Cell Chlor-Alkali Plants source category are acceptable, that 
the 2003 NESHAP provides an ample margin of safety to protect public 
health, and that no additional standards are necessary to prevent an 
adverse environmental effect.
    A two-step evaluation approach was used, similar to the approach 
applied in the Benzene NESHAP, to determine whether or not risks are 
acceptable and to determine whether the 2003 standards provide an ample 
margin of safety to protect public health or needed to be revised to 
meet this goal. We considered health risk and other health information; 
information and additional factors relating to the appropriate level of 
control were also considered--e.g., cost and economic impacts of 
controls, technological feasibility, uncertainties, and any other 
relevant factors.
    Table 2 below provides a summary of the results of the inhalation 
risk assessment for the source category conducted for the January 2021 
proposal. More detailed information on the risk assessment can be found 
in the National Emission Standards for Hazardous Air Pollutants: 
Mercury Cell

[[Page 27007]]

Chlor-Alkali Plants Residual Risk and Technology Review supporting 
document, available in the docket for this action (Docket No.: EPA-HQ-
OAR-2020-0560-0014).

                                Table 2--Inhalation Risk Assessment Summary for the Mercury Cell Chlor-Alkali Plants \1\
                                                                    [Source category]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Maximum          Estimated
                                       Number of      individual      population at   Estimated annual
           Risk assessment             facilities  cancer risk (1-   increased risk   cancer incidence      Maximum chronic      Maximum screening acute
                                          \2\        in-1million)    of cancer  >=1-  (cases per year)    noncancer TOSHI \4\        noncancer HQ \5\
                                                         \3\          in-1 million
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Baseline Actual Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.....................            2            0.004                 0         0.0000003  0.05 (respiratory).....  2 (REL) 7E-4 (AEGL2).
Facility-Wide.......................            2              0.3                 0            0.0001  0.05 (respiratory).....
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Baseline Allowable Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category.....................            2            0.004                 0         0.0000003  0.05 (respiratory).....
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on actual and allowable emissions.
\2\ When the risk assessment was completed in mid-2020, there were 2 operating facilities in the mercury cell chlor-alkali source category and both were
  subject to 40 CFR part 63, subpart IIIII. However, in late 2020 one of those facilities converted to a non-mercury process. Therefore, currently only
  one operating facility remains in the source category.
\3\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\4\ Maximum TOSHI. The target organ with the highest TOSHI for the source category is the respiratory system.
\5\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. The acute
  HQ shown was based upon the lowest acute 1-hour dose-response value, the REL for mercury (elemental). When an HQ exceeds 1, we also show the HQ using
  the next lowest available acute dose-response value.

    As shown in the table above, for the Mercury Cell Chlor-Alkali 
Plants source category, the maximum cancer risk to the individual most 
exposed is less than 1-in-1 million based on actual emissions and 
allowable emissions. The estimated incidence of cancer due to 
inhalation exposures for the source category is 0.0000003 excess cancer 
cases per year, or one excess case every 3 million years. No one is 
exposed to cancer risk greater than or equal to 1-in-1 million based 
upon actual and allowable emissions. We estimated that the maximum 
chronic noncancer TOSHI from inhalation exposure is less than 1 (0.05 
[respiratory]). For both actual and allowable emissions, respiratory 
risks were driven by chlorine emissions from the mercury cell building.
    Based on our refined screening analysis of reasonable worst-case 
acute exposure to actual emissions from the category, the facility 
exceeded an HQ of 1 (the HQ was 2), when compared to the 1-hour REL for 
mercury (elemental). As discussed in section III.C.3.c of the 2021 
proposal preamble, we used an acute hourly multiplier of 10 for all 
emission processes. For this HAP, there are no AEGL-1 or ERPG-1 values 
for comparison, but AEGL-2 or ERPG-2 values are available. For 
elemental mercury, when the maximum off-site concentration is compared 
with the AEGL-2 and ERPG-2, the maximum acute noncancer HQ is well 
below 1 (0.0007). With regard to multipathway exposures, HAP known to 
be persistent and bioaccumulative in the environment (PB-HAP) emissions 
(based on estimates of actual emissions) were reported from both 
facilities in the source category with both exceeding the Tier 1 non-
cancer screening threshold emission rate for mercury. A Tier 2 
screening analysis was conducted, and the facility did not have a 
screening value (SV) greater than 1 for any scenario (the fisher and 
farmer had the highest SV at 0.4). There are no carcinogenic PB-HAP 
emitted from the source category, so there are no cancer SVs to report.
    Considering all the health risk information and factors noted, the 
proposed determination was that the risks are acceptable and that no 
additional standards are necessary to prevent an adverse environmental 
effect. Under the ample margin of safety analysis, we evaluated the 
cost and feasibility of available control technologies and other 
measures that could be applied to further reduce the risks (or 
potential risks) due to emissions of HAP from the source category. 
After careful consideration of these options, since the risks due to 
mercury emissions were already low, we did not propose any additional 
standards for mercury under CAA section 112(f).
2. How did the risk review change for the Mercury Cell Chlor-Alkali 
Plants source category?
    We made no changes to either the risk assessments or our 
determinations regarding risk acceptability, ample margin of safety, or 
adverse environmental effects for the Mercury Cell Chlor-Alkali Plants 
source category since the proposal was published on January 8, 2021. We 
are finalizing the risk review as proposed (86 FR 1362, January 8, 
2021).
3. What key comments did we receive on the risk review, and what are 
our responses?
    The only comment received regarding the risk assessment was that 
one commenter agreed with our assessment that emissions were low and 
that risks were low and at acceptable levels.
4. What is the rationale for our final approach and final decisions for 
the risk review?
    As noted above, in 2021, we proposed that the 2003 Mercury Cell 
Chlor-Alkali NESHAP provides an ample margin of safety to protect 
public health without any revisions. Other than a general agreement 
with the results, there were no specific comments submitted on the risk 
review approach, results, or decision. Therefore, we are finalizing the 
proposed determination that the risks are acceptable, that the 2003 
rule provides an ample margin of safety to protect public health and 
that no additional standards are necessary to prevent an adverse 
environmental effect.

[[Page 27008]]

B. Non-Mercury Option for the Mercury Cell Chlor-Alkali Plants Source 
Category

1. What did we propose related to the non-mercury option for the 
Mercury Cell Chlor-Alkali Plants source category?
    We addressed this issue in all three of our proposed rules issued 
following promulgation of the 2003 rule, in response to the 2004 
petition for reconsideration of the 2003 rule's consideration of 
section 112(d)(2) and (3) beyond-floor options and most recently as 
part of the technology review under section 112(d)(6). In the 2021 
proposal, we further considered our two prior proposals, but did not 
re-propose the option to require non-mercury production technology for 
existing sources, which has been the requirement for new and 
reconstructed mercury cell chlor-alkali production sources since the 
rule was originally promulgated in 2003. This option was considered 
both as part of the technology review under the authority of section 
112(d)(6) and as a ``beyond-the-floor'' option under sections 112(d)(2) 
and (3). As explained in the several proposed rules, selecting this 
option would eliminate all mercury emissions by forcing the remaining 
facility to either convert to a non-mercury technology or close its 
mercury cell chlor-alkali operations. While we did not in 2021, re-
propose this option under either 112(d)(2) and (3) or (d)(6), we 
described this option in detail in the proposed rule's Federal Register 
(FR) notice published on January 8, 2021 (86 FR 1362), including the 
estimated capital costs, annualized costs and cost effectiveness if it 
were to be adopted, and we specifically solicited comments, data, and 
other information regarding this proposed decision. Furthermore, in the 
January 2021 FR document, we discussed and referred to the previous 
2011 proposed rule in which the EPA also analyzed expected capital 
costs, annualized costs and cost effectiveness of the then proposed 
non-mercury option but for which EPA had not taken final action at the 
time of the 2021 proposal.
2. What changed related to the non-mercury option for the Mercury Cell 
Chlor-Alkali Plants source category?
    After consideration of public comments received on the 2021 
proposed rule and further assessment of the expected costs, we have 
changed our 2021 proposed decisions under sections 112(d)(2) and (3) 
and (6) regarding the non-mercury option and the final rule includes an 
amendment that prohibits mercury emissions from existing mercury cell 
chlor-alkali plants as was proposed in 2011 under section 112(d)(2) and 
(3). Existing mercury cell chlor-alkali plants will have three years to 
comply with this requirement.
3. What key comments did we receive on the non-mercury option, and what 
are our responses?
    Comment: One commenter remarked that the EPA must revise MACT 
standards when it finds there have been developments in processes, 
products, or control technologies under CAA section 112(d)(6) to reduce 
emissions to the maximum achievable degree. They further stated that it 
is achievable for facilities to switch to membrane cell technology, as 
demonstrated by the number of facilities that have already made this 
switch since adoption of the 2003 rule, which would eliminate emissions 
of mercury. The commenter also stated that because the EPA is also 
responding to the 2004 petition for reconsideration in this rulemaking 
regarding whether eliminating mercury emissions is achievable, the EPA 
must either promulgate a zero-emissions standard or determine that such 
as standard is not achievable. The commenter added that under the CAA, 
the EPA cannot refuse to set such standards because it does not think 
they are ``reasonable,'' but it must set them at the maximum degree of 
reduction that is achievable.
    Response: We agree that it is technically achievable for facilities 
to switch from mercury cell to membrane cell technology, as there are 
many instances of successful switches spanning the last three decades. 
We also agree that it is technologically achievable, as a section 
112(d)(2) and (3) beyond-floor measure, to require elimination of 
mercury emissions from the single remaining operating existing source. 
However, we disagree with the commenter's assertion that the EPA must 
promulgate a standard solely based on technical achievability in the 
context of section 112(d)(6). Section 112(d)(6) requires the EPA to 
review and revise emission standards as necessary, considering 
developments in practices, processes, or control technologies, but does 
not require revisions for all developments that are technically 
achievable. Other factors are considered, including cost, economic 
impacts, physical limitations of the site, etc.
    Nevertheless, based on consideration of public comments, and after 
reassessing the costs and feasibility of converting to the non-mercury 
technology, we have determined that the non-mercury option is 
technically and economically feasible and is cost effective and 
therefore reasonable to impose under both sections 112(d)(2) and (3) 
and (d)(6). As explained elsewhere in this preamble, we estimate the 
annualized costs to convert to a membrane process would be $2.7 million 
per year (2019 dollars), with cost-effectiveness of $21,500 per pound 
of reduced mercury emissions. This cost effectiveness is within the 
range of cost effectiveness values the EPA has accepted historically 
for mercury reduction. For example, in the 2012 Mercury and Air Toxics 
(MATS) final rule, the EPA finalized a beyond-the-floor standard for 
mercury with a cost effectiveness of $22,496 per pound (based on 2007 
dollars), which would be approximately $27,500 per pound based on 2019 
dollars. Furthermore, we conclude that conversion to a non-mercury 
process is clearly feasible, as demonstrated by the six mercury cell 
facilities in the U.S. that have converted to the non-mercury membrane 
process since the year 2000. Additionally, non-mercury chlorine 
production accounts for more than 98% of chlorine production in the 
U.S.
    Comment: One commenter maintained that the EPA's vague 
characterizations of costs and its ignorance of current costs for the 
one remaining facility to switch to membrane technology did not 
constitute an excuse for failing to determine whether the measure is 
achievable. The commenter said that the Agency has had 17 years since 
the 2004 petition for reconsideration to gather the data it needs, and 
any uncertainty about costs due to the EPA's failure to gather the 
necessary data is not a lawful or reasonable basis for not setting a 
zero-emissions standard for mercury.
    Response: We disagree with the commenter's characterization of our 
assessment of the costs of conversion. While the EPA did not commission 
a comprehensive detailed study to assess the costs specifically for the 
conversion of the West Virginia mercury cell chlor-alkali unit to 
convert to membrane cells, the EPA did update the previous analysis to 
incorporate new information to ensure that the estimated costs 
reflected ``current'' costs expected to be incurred for a conversion. 
The commenter did not mention or provide any specific comments on the 
updated analysis.
    The foundation for the analysis was the series of evaluations 
conducted by the EPA in 2008 through 2010, in support of the 2008 and 
2011 proposed rules. The EPA first presented our evaluation of impacts 
of requiring conversion of all operating mercury cell

[[Page 27009]]

chlor-alkali production plants to non-mercury technology in 2008. Based 
on comments received after the June 11, 2008, proposed amendments (73 
FR 33258), we updated this analysis and released it for public review 
in June 2009. Comments were received on this revised analysis, and a 
second revision was released for public review in September 2009. The 
EPA received comments on this second revision of the analysis and 
issued another revision in April 2010. Therefore, the 2010 analysis, 
which was based on extensive research by the EPA, had undergone three 
rounds of public review by the environmental community and the industry 
before it was relied upon to support the 2011 proposed rule.
    The 2020 update to the 2010 conversion cost analysis involved 
several steps to ensure that the cost estimates were current. These 
included converting 2010 capital cost estimates, the savings associated 
with compliance with the mercury cell room monitoring program, and the 
electricity savings, to a 2019 base year. It also included 
incorporation of the reported costs of the latest conversion of a 
mercury cell facility in the U.S., which was the Ashta facility in Ohio 
that completed its conversion in late 2020. In addition, the 2020 
analysis considered the conversion cost estimate specifically provided 
for the West Virginia facility by the previous owner in public comments 
on the 2011 proposal and updated that estimate to base year 2019.
    Comment: One commenter (the owner of the single operating mercury 
cell facility) noted that the facility has not revisited the cost 
associated with converting to a non-mercury process since 2012, but 
they believe it is significantly higher than the EPA's estimate of $69 
million.
    Response: While the EPA recognizes that the facility may not have 
recently performed an update of the cost to convert their mercury cell 
unit to membrane technology, we believe there is sufficient information 
available to obtain a reasonable estimate of this cost. In our 2020 
analysis, we estimated the conversion costs using three approaches. One 
was to base the capital cost of conversion solely on the highest cost 
factor (dollars per ton of chlorine production capacity) from the 
conversions considered in the 2010 analysis (after adjusting to a 2019 
base year). The second approach used the cost factor calculated from 
the reported cost for the most recent conversion at the Ashta facility 
in Ohio. The cost factor for this Ashta conversion was over 20 percent 
higher than the highest cost factor from the previous conversions after 
updating them to a 2019 base year. The third approach was to 
incorporate the Ashta factor into an average of all the cost factors 
for conversions in the U.S. since 2003. These factors, which were in 
units of dollars per ton of chlorine production capacity, were then 
applied to the site-specific production capacity of the West Virginia 
mercury cell unit. The resulting estimates of the capital cost of 
conversion of the West Virginia facility using these three approaches 
were approximately $76 million, $92 million, and $58 million, 
respectively (in 2019 dollars). Given all the site-specific factors 
that are inherent in the cost of conversion, we do not believe it is 
appropriate to base an estimate on the factor from the conversion of a 
single facility. So, we did not select either of the first two options 
described above. We also did not want to potentially bias our estimate 
low, so we did not select the third option (average factor for five 
facilities that have converted since 2003). Therefore, we calculated 
the average cost between the three options ($69.3 million) and selected 
that average as our estimated cost of conversion for our consideration 
for our 2021 proposal. Considering the inflation that has occurred 
since 2019, the updated capital cost of conversion estimate is $80.7 
million (in 2021 dollars). Our confidence in this estimate was 
bolstered by a comparison of this result with the estimate that was 
specifically provided earlier in 2011 for the West Virginia facility by 
its previous owner. This estimate, when converted to 2019 to be 
consistent with the year for our cost analysis, was $69.4 million (or 
$80.8 million for 2021 base year). Since the commenter did not provide 
any updated information in response to the 2020 analysis and 2021 
proposed rule, we continue to maintain that our estimate is a 
reasonable estimate of the capital costs of converting the West 
Virginia mercury cell unit to membrane cell technology.
    Comment: One commenter stated that the EPA's proposal ignored the 
U.S. obligations under the Minamata Convention on Mercury, which is a 
global treaty that requires the phase-out of manufacturing processes 
using mercury. The commenter remarked that under Article 5(2), the 
phase-out date for chlor-alkali production using mercury is 2025, 
unless an exemption is filed. The commenter noted that an exemption was 
filed for these processes in the U.S., and the phase-out date is now 
2030. According to the commenter, since companies are typically given 
three years to comply with MACT standards, a final rule requiring the 
phase-out of mercury would be required to be promulgated by the end of 
2027 for the U.S. to meet its obligations under the Minamata 
Convention. The commenter stated that since a final rule in 2021 that 
does not require elimination of mercury would put the next 8-year 
review completion time at the end of 2029 at the earliest, the U.S. 
will then be out of compliance with the Minamata Convention. The 
commenter stated that the EPA must issue a new proposal explaining how 
the 2030 phase-out deadline will be met.
    Response: We agree with the commenter's summary of the U.S. 
obligations under the Minamata Convention agreement. We also agree that 
a NESHAP standard adopted under the authority of section 112 of the CAA 
is a valid approach to meet this obligation. In fact, during treaty 
negotiations, the U.S. specifically concluded that CAA section 112 
gives the EPA the authority to require elimination of mercury 
emissions. We also agree with the commenter's conclusions about the 
timing of when a NESHAP would need to be promulgated. Assuming a 3-year 
compliance timeframe would be needed for a final rule requirement that 
prohibits mercury emissions, a section 112 NESHAP would need to either 
be finalized as part of this review, or a separate ``out of cycle'' 
review would be needed prior to 2027 to meet the current phase-out date 
of 2030 required under the Convention. (More information regarding the 
Minamata Convention is available at: https://www.mercuryconvention.org/en/about).
    Comment: One commenter remarked that the environmental impacts the 
EPA cites as a reason not to require a zero-emission standard for 
mercury are actually environmental benefits. The commenter stated that 
the 1,000 pounds of mercury that are discharged to the environment 
every year would be eliminated. The commenter also stated that the EPA 
ignored the fact that mercury-contaminated piping and equipment must be 
removed at some point, and it is just a question of when. The commenter 
added that the costs of storing and moving mercury to a secure location 
is not a new expense, as the facility made a choice to continue 
operations with mercury past the date the Mercury Export Ban of 2008 
(Pub. L. 110-414) went into effect in 2013, and it determined at that 
point to assume those costs.
    Response: We estimate that the non-mercury requirement would 
eliminate just over 125 pounds of mercury released to the atmosphere 
per year.

[[Page 27010]]

Furthermore, at proposal we stated the following: ``The EPA also 
examined the non-air impacts associated with switching from mercury 
cell to non-mercury cell processes. For 2019, the West Virginia 
facility reported a total of 898.1 pounds of non-air mercury releases. 
This consists of 9 pounds to streams/water bodies, 883.3 pounds to 
Resource Conservation and Recovery Act, Subtitle C Landfills, and 5.8 
pounds to other offsite sources. All these releases would be eliminated 
with the conversion to non-mercury cell processes.'' (86 FR 1382-1383)
    We also acknowledge the point made by the commenter regarding the 
costs associated with moving the mercury recovered from a conversion 
and storing it. Even without a regulatory requirement to eliminate 
mercury emissions from existing sources, the mercury cell unit would 
eventually reach the end of its useful life and be shut down or 
replaced. Since the standards for new and reconstructed sources in 
subpart IIIII prohibit mercury emissions, the owner or operator could 
not replace the unit with another mercury cell process. Even without 
this standard, which has been in place since 2003, it is reasonable to 
assume that a new mercury cell facility would not be built. Prior to 
the promulgation of subpart IIIII, the use of the outdated mercury cell 
technology had been declining for decades and no new mercury cell 
facility had been constructed since the early 1970s. Hence, we agree 
that the owner most likely recognized this future cost when the 
decision was made not to convert prior to the effective date of the 
mercury export ban. Therefore, we conclude that the costs of the 
mercury storage should not be attributed to the non-mercury option 
under this rulemaking.
    The cost of this mercury storage was estimated to be just over 
$53,000 per year in our 2020 conversion cost analysis. Removing these 
mercury storage costs lowers the overall estimated annual cost, which 
includes the annualized capital cost, electricity savings and reduced 
compliance costs from $2.77 million to just over $2.7 million. This 
improves the cost effectiveness from just over $22,000 per pound of 
mercury released to the air to around $21,500 per pound. In addition, 
as noted above, it also results in the reduction of around 900 pounds 
of mercury releases per year to other media.
    Comment: One commenter registered agreement with the EPA's proposal 
to not require the elimination of mercury and stated that the NESHAP 
should not include a zero-mercury standard at this time. The commenter 
added that the single operating facility operates with low mercury 
emissions and pointed out that risks due to mercury are already low and 
at acceptable levels. However, another commenter expressed support for 
a zero-emission policy and a switch to non-mercury polluting processes 
at the West Virginia facility. This commenter stated that while the 
current mercury emissions may be in compliance with the 2003 NESHAP's 
standards, effort should be made to increase sustainable industrial 
processes if possible. According to the commenter, considering the 
cost-benefit analysis, it would be more beneficial for the chlor-alkali 
plant to transition sooner rather than later because the plant will 
eventually have to transition or adopt a zero-mercury emission policy 
as our green infrastructure increases. The commenter added that when 
considering pollution, especially mercury, the goal should be zero, 
regardless of its economic impact. Additionally, the commenter 
supported policies that are more proactive in tackling pollution 
because accidents can happen and they're typically more of an economic 
burden than taking proactive measures. Further, the commenter stated 
that even if the data shows no benefits to human health or the 
environment from further reducing the mercury emissions at the West 
Virginia plant, it would ultimately be one step closer to the national 
transition to cleaner, more sustainable industry.
    Response: As discussed above in section IV.A of this preamble, the 
first commenter is correct that our conclusion of the section 112(f) 
residual risk assessment was that health risks due to emissions of HAP 
from the Mercury Cell Chlor-Alkali Plants source category are 
acceptable, that the 2003 NESHAP provides an ample margin of safety to 
protect public health, and that no additional standards are necessary 
to prevent an adverse environmental effect. While the recommendations 
of the second commenter generally lack any statutory authority to 
implement measures for a ``green infrastructure'' to ``transition to 
cleaner, more sustainable industry,'' their point about a transition to 
zero mercury pollution is recognized.
    The residual risk assessment conducted under the authority of 
section 112(f) is focused on the local impacts (within 50km) directly 
resulting from HAP emissions from a NESHAP affected source. This type 
of assessment does not necessarily capture all the potential risks or 
impacts associated with mercury emissions. Mercury is a highly 
neurotoxic contaminant that enters the food web as a methylated 
compound, methylmercury. The contaminant is concentrated in higher 
trophic levels, including fish eaten by humans. Mercury is emitted to 
the air from various anthropogenic and natural sources. These emissions 
transport through the atmosphere and eventually deposit to land or 
water bodies. This deposition can occur locally, regionally, or 
globally, depending on the form of mercury emitted and other factors 
such as the weather. The form of mercury emitted from the single 
remaining operating plant is estimated to be about 98 percent elemental 
and two percent divalent mercury. Gaseous elemental mercury can be 
transported very long distances, even globally, to regions far from the 
emissions source (becoming part of the global ``pool'') before 
deposition occurs. Inorganic ionic (divalent) mercury has a shorter 
atmospheric lifetime and can deposit to land or water bodies closer to 
the emissions source. Furthermore, elemental mercury in the atmosphere 
can undergo transformation into ionic mercury, providing a significant 
pathway for deposition of emitted elemental mercury (UNEP, Global 
Mercury Assessments, available at: https://www.unep.org/resources/publication/global-mercury-assessment-2018).
    Therefore, even though the estimated risks due to the mercury 
emissions are low based on our residual risk assessment, and the 
results of the residual risk assessment do not necessitate additional 
regulation to meet the requirements of CAA section 112(f), we agree 
that there is merit in eliminating mercury emissions where it is 
technically and economically feasible to do so, consistent with other 
statutory authority and requirements. And, as the second commenter 
points out, this is certainly possible in this situation, and the plant 
would need to ultimately eliminate mercury emissions anyway in order 
for the United States to meet its obligations under the Minamata 
Convention.
4. What is the rationale for our final approach for the non-mercury 
option?
    As noted above, we are finalizing an amendment that prohibits 
mercury emissions from existing mercury cell chlor-alkali plants. Our 
rationale for this decision is based on the following points. First, 
our re-evaluation of the costs and associated emission reductions 
reveal that the cost effectiveness is within the range considered 
reasonable by the EPA for mercury and based on our economic analysis, 
the estimated annualized costs are only about 0.04 percent of the

[[Page 27011]]

annual revenue of the facility's ultimate parent company in 2020 and 
therefore the amendment is reasonable as a beyond-floor standard under 
section 112(d)(2) and (3). Second, this action will also eliminate the 
non-air releases that occur from the remaining mercury cell plant. 
Third, using the authority under section 112(d) of the CAA at this time 
is the most effective mechanism to ensure the U.S complies with the 
Minamata Convention agreement by the 2030 deadline. Finally, as 
mentioned above, we conclude that conversion to a non-mercury process 
is clearly feasible and has been shown to be a development in 
practices, processes and control technologies under section 112(d)(6), 
as demonstrated by six facilities in the U.S. that have converted to 
the non-mercury membrane process since the year 2000. Some of these 
points are discussed in more detail below.
    In response to a comment discussed above, we adjusted the annual 
costs to remove the mercury storage cost. This resulted in the cost 
effectiveness of the non-mercury option decreasing slightly to $21,500 
per pound of mercury emission reduction. While this cost effectiveness 
is near the upper end of the range of cost effectiveness values the EPA 
has accepted historically for achievable mercury control, the EPA has 
previously determined that cost effectiveness values higher than this 
are acceptable and achievable. For example, in the 2012 MATS final 
rule, the EPA finalized a beyond-the-floor standard for mercury of 
$22,496 per pound (based on 2007 dollars), which would be about $27,500 
per pound based on 2019 dollars. Therefore, we conclude that the cost 
effectiveness of $21,500 per pound of mercury emissions reduction is 
reasonable especially given the other factors described above, and we 
have decided to finalize the amendment to prohibit mercury emissions 
from existing sources as an achievable beyond-floor measure under 
section 112(d)(2) and (3).
    As noted above, we evaluated the economic impacts of this amendment 
and determined that the impacts are not substantial, with the 
annualized costs being less than 0.04 percent of sales for the subject 
facility's ultimate parent company (Westlake). We determined that the 
environmental benefit of the non-mercury option warranted these 
economic impacts.
    The primary reasons provided at proposal for discussing but not re-
proposing the non-mercury option were related to costs, cost 
effectiveness, and uncertainties. For example, in the January 2021 
proposal FR document, the EPA stated that ``first, mercury emissions 
are based on calculations and assumptions regarding the facility's 
emissions (no test data are available for this facility), and second, 
because there are uncertainties with the cost estimates from the 2011 
proposal as being transferable to the remaining facility. In the 2011 
proposal, the estimated cost effectiveness was $20,000 per pound for 
the industry (see 76 FR 13852, March 14, 2011), but this was 
substantially based on the studies conducted for the two no longer 
operating sources.'' (86 FR 1378-1379)
    While no additional emissions data based on testing was submitted 
in response to the 2021 proposal, we point out that subpart IIIII 
requires that measurements of the stack emissions be taken. The 
estimates reported by the West Virginia facility that were used in our 
analyses for fugitive emissions (121.4 pounds per year) are lower than 
the average level of 362 pounds per year per plant found during the 
extensive study conducted by the EPA prior to the 2008 proposal (see 
description in the June 11, 2008, proposal at 73 FR 33263-33266). 
Therefore, if the confidence is lacking regarding these estimates, it 
is realistic to consider that emissions, and thus emission reductions, 
would likely only be higher. This would result in improved cost 
effectiveness values (i.e., the requirements would be more cost 
effective), providing further justification for our decision to 
finalize the non-mercury option.
    In the 2021 proposal we stated, ``Based on consideration of the 
updated costs and cost effectiveness and uncertainties, and given the 
passage of time, and the fact that the cost- effectiveness data and 
analysis done in 2011 were based on two facilities that are no longer 
operating, we question whether those 2011 analyses would still be 
transferable to the one remaining operating facility.'' (86 FR 1378) 
Upon additional consideration, we have determined that this point is 
not relevant to the decision regarding the cost effectiveness of a non-
mercury standard for the West Virginia facility. In 2011, we calculated 
an average cost effectiveness for the conversion of the four mercury 
cell facilities operating at that time. The range was between $13,000 
to $31,000 per pound for the four individual facilities. However, the 
estimated cost effectiveness values for the two facilities that closed 
prior to 2020 is not determinative of the estimate of the conversion 
cost for the West Virginia facility. Also, the cost effectiveness for 
these two facilities does not compel what the EPA considers a 
reasonable cost effectiveness level for mercury. Therefore, we now 
reject the two major points used as rationale in the 2021 proposal for 
not accepting and proposing the non-mercury option. We are confident 
that the mercury emissions estimates for the West Virginia facility are 
reliable and, if anything, are underestimated. We also have determined 
that the cost estimate is reasonable and applicable and could be even 
more cost effective than presented here due to potential 
underestimation of the emissions. Consequently, the non-mercury option 
is a reasonable beyond-floor measure under section 112(d)(2) and (3), 
and the fact that six mercury cell facilities have converted to non-
mercury membrane technology since 2000 and only a single mercury cell 
source remains at a facility that already has two non-mercury chlorine 
production units shows that is necessary to revise our existing source 
standard to take into account developments in practices, processes and 
control technologies.
    Regarding the Minamata Convention on Mercury, this is a global 
treaty to protect human health and the environment from the adverse 
effects of mercury. It was agreed at the fifth session of the 
Intergovernmental Negotiating Committee on mercury in Geneva, 
Switzerland on January 19, 2013, and adopted later that year on October 
10. The Minamata Convention entered into force on August 16, 2017.
    Major highlights of the Minamata Convention include a ban on new 
mercury mines, the phase-out of existing ones, the phase out and phase 
down of mercury use in a number of products and processes, control 
measures on emissions to air and on releases to land and water, and the 
regulation of the informal sector of artisanal and small-scale gold 
mining. The Convention also addresses interim storage of mercury and 
its disposal once it becomes waste, sites contaminated by mercury, and 
health issues.
    Under the Minamata Convention, the U.S. has specifically addressed 
mercury cell chlor-alkali production. For example, in the registration 
for an extension of the mercury phase out deadline from 2025 to 2030, 
the U.S. stated the following:
    ``Pursuant to Article 6, paragraph 1 of the Minamata Convention on 
Mercury, the United States hereby registers for an exemption from the 
phase-out date listed in Annex B for the use of mercury in chlor-alkali 
production.'' \2\ The United States also provides the

[[Page 27012]]

following statement explaining the need for the exemption:
---------------------------------------------------------------------------

    \2\ https://www.mercuryconvention.org/en/parties/exemptions.
---------------------------------------------------------------------------

    ``The United States supports the phase-out of mercury use in chlor-
alkali production facilities. It has implemented domestic strategies to 
encourage a timely transition to mercury-free alternative technologies 
with a view to phasing out all mercury use in domestic chlor-alkali 
production facilities. New or reconstructed chlor-alkali production 
facilities in the United States are already effectively prohibited from 
using mercury under section 112 of the Clean Air Act. See 40 CFR 
63.8190. Most mercury cell chlor-alkali facilities in the United States 
have already closed or converted. While there were 14 such facilities 
in 1998, only two remained as of late 2013. The United States will, 
pursuant to Article 6, paragraph 7, withdraw this exemption if that 
becomes possible prior to its expiration date.'' \3\
---------------------------------------------------------------------------

    \3\ Ibid.
---------------------------------------------------------------------------

    Therefore, the U.S. is committed to phasing out all mercury 
emissions in domestic chlor-alkali facilities by 2030. The EPA is not 
aware of any plans by the owner of the lone remaining mercury cell 
chlor-alkali facility in West Virginia to close or convert their 
mercury cell facility before 2030. Therefore, we have determined that 
it is necessary to require this action to ensure the facility converts 
or closes the mercury cell chlor-alkali production process in order to 
eliminate mercury emissions and section 112 of the CAA provides an 
appropriate regulatory mechanism to enact such a requirement to 
eliminate emissions. The two main options regarding timing are: (1) 
Promulgate a non-mercury standard at this time under section 112(d)(2) 
and (3) and/or section 112(d)(6); or (2) promulgate a non-mercury 
standard by fall 2027 (i.e., before the next 8-year cycle for a 
technology review required by section 112(d)(6)).
    As pointed out by commenters, the next 8-year review will not be 
required until 2030. If a non-mercury standard was promulgated in 2030 
and included the 3-year compliance date allowed by CAA section 112, the 
phase-out would not occur in time to comply with the 2030 deadline. We 
do not think it is prudent to plan a separate ``out of cycle'' review 
to promulgate a non-mercury standard in 2027, especially since the 
review shows that the non-mercury standard is technologically feasible, 
cost effective and will not impose significant economic impacts at this 
time, and there is no reason to think a decision would be any different 
in 2027. Therefore, we concluded that the best option to ensure 
compliance with the Minamata Convention is to promulgate a non-mercury 
standard at this time.
    We recognize that we did not specifically propose this option in 
the January 2021 proposal. However, we did include it as an option that 
was considered and described it in detail, we provided our analysis of 
this option and specifically requested comment on the option. 
Specifically, we stated the following:
    ``However, we are soliciting comments, data, and other information 
regarding these proposed decisions, including data and information 
regarding the costs, cost effectiveness, non-air, and economic impacts 
and other relevant information regarding whether the NESHAP should 
include a non-mercury standard as either a beyond-the-floor MACT 
standard or a revised standard under the technology review, and whether 
the proposed work practices for chlorine emissions and proposed 
amendments to the mercury work practices would be necessary if a non-
mercury standard were to be adopted.''
    EPA also stated that ``We intend to consider any such submitted 
data and information, in addition to the data and information contained 
in the records for the 2008 and 2011 proposals and in this proposal, in 
reaching final conclusions under CAA sections 112(d)(2) and (6) 
regarding a non-mercury standard.'' (86 FR 1383)
    Furthermore, the EPA proposed the non-mercury option in 2011 and 
referred to this 2011 proposal in the January 2021 FR document. 
Therefore, we provided sufficient notice of the potential that we would 
finalize a non-mercury option, and we are finalizing the non-mercury 
requirement based on a logical outgrowth of comments on our proposal 
and the record that public commenters had an opportunity to review and 
address.

C. Technology Review for the Mercury Cell Chlor-Alkali Plants Source 
Category

1. What did we propose pursuant to CAA section 112(d)(6) for the 
Mercury Cell Chlor-Alkali Plants source category?
    Pursuant to CAA section 112(d)(6), we proposed amendments to the 
rule that would have required the combination of both a cell room 
monitoring program to continuously monitor mercury vapor in the cell 
room and a suite of equipment standards and work practices to reduce 
fugitive mercury emissions. This is different from the NESHAP 
promulgated in 2003, which required either the equipment standards and 
work practices or the cell room monitoring program. As described above, 
we also evaluated the non-mercury option under our section 112(d)(6) 
technology review.
2. How did the technology review change for the Mercury Cell Chlor-
Alkali Plants source category?
    As discussed above in section IV.B, we changed our decision related 
to the non-mercury option and are promulgating a prohibition of mercury 
emissions from the source category. The result of this final amendment 
prohibiting mercury emissions will be that there will no longer be any 
operating mercury cell chlor-alkali plants in the U.S. after May 6, 
2025.
3. What key comments did we receive on the technology review, and what 
are our responses?
    The only comment received on our proposed technology review, other 
than those related to the non-mercury option discussed above in section 
IV.B.3, was one from the facility that clarified that the existing 
continuous monitor analyzers for mercury at the facility are capable of 
detecting mercury concentration of 0.1 [micro]g/m\3\, which would meet 
the EPA's proposed detection requirements.
4. What is the rationale for our final approach for the technology 
review?
    The rationale for our final decision regarding the non-mercury 
option is discussed above in section IV.B.4. Regarding the cell room 
monitoring program and equipment and work practice standards to reduce 
fugitive mercury emissions, the facility complies with the fugitive 
mercury standards by operating a continuous cell room monitoring 
program in accordance with paragraph 63.8192(g) as an alternative to 
the equipment standards and work practices in paragraphs 63.8192(a) 
through (d). However, while not required to do so under the NESHAP 
promulgated in 2003, the facility also implements those equipment 
standards and work practices. Therefore, the EPA determined that the 
combination of implementing a cell room monitoring program and 
performing work practices constitutes a development in emissions 
control practices and is finalizing the proposed requirement that both 
a cell room monitoring program and equipment and work practices be 
implemented during the period of up to 3 years before the facility 
converts the mercury cell process to a non-mercury process or closes 
the mercury cell process.

[[Page 27013]]

D. Amendments Pursuant to Sections 112(d)(2) and (3) and (h) for the 
Mercury Cell Chlor-Alkali Plants Source Category

1. What did we propose pursuant to CAA section 112(d)(2) and (3) and 
(h) for the Mercury Cell Chlor-Alkali Plants source category?
    Pursuant to CAA sections 112(d)(2) and (3) and (h), in 2021 we 
proposed amendments to the rule that would have required a leak 
detection and repair program to identify chlorine equipment leaks in 
the cell room and throughout the other parts of the mercury cell chlor-
alkali production facility affected source that handle and process the 
chlorine gas produced. The proposed rule would have also required that 
chlorine monitors be installed and operated continuously throughout the 
affected source and that each time one of these sensors measured a 
chlorine concentration of 2 ppmv or greater, a complete inspection for 
leaks of all equipment containing 5 percent chlorine by volume would 
have been required within 1 hour of detection.
    In addition, we evaluated the beyond-the-floor non-mercury option 
under our consideration of section 112(d)(2) and (3); however, we did 
not propose the non-mercury standard in the January 8, 2021 proposal.
2. How did the decision related to CAA section 112(d)(2) and (3) change 
for the Mercury Cell Chlor-Alkali Plants source category?
    As discussed above in section IV.B, we changed our decision related 
to the non-mercury option and are promulgating a prohibition of mercury 
emissions from the source category. The result of this final amendment 
prohibiting mercury emissions will be that there will no longer be any 
operating mercury cell chlor-alkali plants in the U.S. after May 6, 
2025.
3. What key comments did we receive on our proposed decision related to 
CAA sections 112(d)(2) and (3) and (h), and what are our responses?
    As discussed above in section IV.B.3, comments were received 
regarding the proposed determination not to require the non-mercury 
option as a beyond-the-floor requirement. Comments were also received 
related to the proposed fugitive chlorine requirements. In addition, 
comments were received claiming that standards should have been 
proposed for emissions of HCl. These comments, along with responses 
from the EPA, are provided below in this section.
    Comment: The single operating facility provided several comments 
regarding the proposed requirements to reduce chlorine emissions. While 
they corrected the EPA's assumption that the cell room was under 
negative pressure, they noted that most of the equipment containing 
chlorine gas is under negative pressure, which would be excluded from 
the proposed leak detection requirements. They noted that the facility 
already complies with most of the proposed fugitive chlorine 
requirements, and they explained how they would comply with the 
additional requirements. They agreed that the proposed olfactory 
observations are appropriate versus visual or auditory inspections, due 
to the low odor threshold of chlorine. They did, however, register 
concern about the chlorine leak repair requirements, noting that final 
repairs to leaks from some causes may take more than one day to 
complete, as required in the proposal. They also provided responses to 
the EPA's requests for comments regarding the proposed requirements for 
continuous chlorine sensors and the proposed 2 parts per million by 
volume (ppmv) action level and averaging time. In response to the EPA's 
request for comment regarding whether the EPA should specify sensor 
placement locations, they expressed concern about placing chlorine 
sensors in the cell room, as they stated that the high magnetic field 
in the cell room has historically caused unreliable transmitter 
responses. They indicated that, if the EPA finalized a requirement to 
place chlorine sensors in the cell room, additional time would be 
needed to comply with the standard, as the facility would need to 
evaluate whether the use of a chlorine sensor(s) in the cell room is 
technically feasible and, if feasible, to procure and install the 
sensors.
    Response: The EPA appreciates the effort provided by the commenter 
to carefully review the proposed fugitive chlorine requirements, to 
provide thoughtful comments, and to put forth preliminary ideas on how 
they would comply. We also appreciate the concerns raised about the 
repair timing requirement and the placement of chlorine sensors in the 
cell room. Based on these comments, we have revised the final 
requirements to add time to make repairs, which would allow time to 
obtain equipment that is not kept onsite, by increasing the time for 
final repairs to be made from 24 to 72 hours. Further, based on these 
comments and the technical feasibility of placing sensors in certain 
locations, we have not added requirements stipulating sensor locations 
in the final rule. Finally, we agree that an action level for equipment 
inspections based on a single sensor reading may not be indicative of a 
problem that warrants special investigation. Accordingly, we have 
revised the action level that triggers an inspection of all chlorine-
containing equipment to be detection by a sensor of a one-hour average 
chlorine concentration of 2 ppmv or greater.
    Comment: One commenter stated that the EPA must set emissions 
standards for HCl. The commenter contended that even if the HCl 
emissions are from direct synthesis HCl production units, these units 
are part of the mercury cell chlor-alkali plant and must be regulated. 
The commenter stated that these units would be affected sources because 
they are ``cell rooms and ancillary operations used in the manufacture 
of product chlorine, product caustic, and by-product hydrogen at a 
plant site'' and ``processes and associated operations needed for 
mercury recovery from wastes at a plant site.''
    Response: We disagree with the commenter's rationale of why the 
direct synthesis HCl production units would be part of an affected 
source under subpart IIIII. They are not part of the cell room or the 
ancillary operations used in the manufacture of product chlorine, 
product caustic, or by-production hydrogen. In fact, the HCl production 
units are downstream operations from the chlor-alkali process, as they 
use the product chlorine and by-product hydrogen to create HCl. 
Additionally, these units are not associated with the processes needed 
for the recovery of mercury.
    While not cited by the commenter, the EPA has previously considered 
direct synthesis HCl units co-located with chlor-alkali plants to be 
part of the chlor-alkali plant. In the July 3, 2002, proposal for the 
chlorine production source category, the EPA stated ``Since chlor-
alkali processes produce both chlorine and hydrogen, it is common for a 
direct synthesis HCl production unit to be incorporated into a chlor-
alkali facility. Therefore, we consider these direct synthesis HCl 
production units to be a part of the chlor-alkali facilities.'' (67 FR 
44713). The HCl (and chlorine) emissions from the co-located direct 
synthesis HCl plants were included in the risk assessment that led to 
the EPA's decision in 2003 not to develop any NESHAP for non-mercury 
cell chlor-alkali plants and to delete the non-mercury subcategory. 
Further, because these units were considered part of the deleted non-
mercury cell chlorine production subcategory, they were specifically 
exempted from the HCl

[[Page 27014]]

NESHAP, 40 CFR subpart NNNNN, at 63.8985(d).
    At the West Virginia facility, there are three chlor-alkali units: 
The mercury cell unit and two diaphragm cell units. According to the 
air permit for the facility, the diaphragm cell units produce 
approximately four times as much chlorine as the mercury cell unit. 
Therefore, if the HCl production units were assigned to one of the 
chlorine production subcategories based on the contribution of the 
chlorine and hydrogen contributed, they would be considered part of the 
non-mercury cell subcategory of chlor-alkali plants. In addition, when 
the EPA finalized the decision to delete the non-mercury subcategory on 
December 19, 2003, we stated ``we have clarified that chlorine and HCl 
emissions from the absorber vents of direct synthesis HCl production 
units at chlor-alkali facilities, as well as the associated storage 
tanks and transfer operations specified above, are included in the non-
mercury cell chlorine production subcategory . . .'' (68 FR 70948)
    As shown through this cited history, the EPA has clearly 
established that HCl direct synthesis units are not part of the mercury 
cell chlor-alkali source category, and we are not pursuing their 
regulation under subpart IIIII.
    Comment: One commenter stated that the EPA proposed to limit the 
applicability of the rule with changes to -63.8182, -63.8184(a) and 
definitions in -62.8266. The commenter asserted that the EPA did not 
provide any explanation or justification for these proposed changes, 
which is a violation of the CAA and makes it impossible to determine 
what the EPA is intending to accomplish. The commenter's interpretation 
was that the EPA was changing the existing regulation to avoid 
regulating HCl emissions from the plant. The commenter stated that if 
that is the case, the EPA is acting unlawfully by attempting to bypass 
its statutory obligations to regulate all HAP and HAP emission points 
within a source category.
    Response: The commenter is correct that these changes were not 
explained in the January 2021 proposal. They were changes that were 
proposed in both the 2008 proposal and the 2011 supplemental proposal, 
with the purpose of ensuring that a mercury thermal recovery unit 
affected source at a site where the mercury cell production facility 
was either converted or closed would continue to be subject to the 
emission limitations while processing the wastes from the closed 
mercury cell plant. Since the single remaining mercury cell chlor-
alkali plant does not have a thermal mercury recovery unit, these 
changes are not necessary and should not have been included. They are 
in no way related to HCl emissions from the plant. In fact, as noted 
above, these amendments were holdovers from the 2008 proposal and the 
2011 supplemental proposal when only mercury emissions were under 
consideration.
4. What is the rationale for our final approach for the CAA sections 
112(d)(2) and (3) and (h)?
    The rationale for our final decision regarding the non-mercury 
option is discussed above in section IV.B.4. For the fugitive chlorine 
work practices, the facility voluntarily implements work practices that 
are consistent with the proposed requirements and represents the MACT 
floor. As these chlorine emissions are fugitive in nature resulting 
from potential equipment leaks, they cannot be emitted through a 
conveyance designed and constructed to emit or capture such pollutant 
or measured. Therefore, we are finalizing the proposed amendments 
requiring work practices to minimize chlorine emissions. Further, as 
discussed above, we are not developing standards under section 
112(d)(2) and (3) for the HCl emissions from the direct synthesis HCl 
production units at the West Virginia site.

E. Amendments addressing emissions during periods of startup, shutdown, 
and malfunction and other topics?

1. What did we propose related to emissions during periods of startup, 
shutdown, and malfunction and other topics?
    We proposed revisions related to emissions during periods of 
startup, shutdown, and malfunction (SSM); provisions for electronic 
submission of performance test results, performance evaluation reports, 
and Notification of Compliance Status (NOCS) reports; and corrections 
of various errors in compliance provisions in the NESHAP.
2. How did the decision related to emissions during periods of startup, 
shutdown, and malfunction and other topics change?
    No changes have been made regarding our decisions concerning 
periods of SSM and the corrections of various compliance provisions in 
the current rule. For submission of performance test results, 
performance evaluation reports, and Notification of Compliance Status 
(NOCS) reports, we have determined it is necessary for the facility to 
switch to electronic reporting, considering the timing of the final 
non-mercury emission standard and related upcoming closure or 
conversion of the one remaining mercury cell chlor-alkali unit.
3. What key comments did we receive on proposed decision related to 
emissions during periods of startup, shutdown, and malfunction and 
other topics?
    Comment: One commenter relayed several concerns regarding the 
proposed startup, shutdown, and malfunction provisions. According to 
the commenter, higher mercury emissions may occur during startup due to 
the hydrogen vent system and its control device, which will cause 
compliance concerns until alternative work practices can be developed 
to reduce emissions from this system. The commenter stated, at the time 
they submitted public comments, that the control device cannot be 
operated until the exhaust stream composition can be regulated, and the 
facility would need additional time to evaluate operational methods to 
improve operation of the control device. The commenter added that 
additional time would also be needed to determine the modifications 
necessary to reduce emissions during startup, to develop and implement 
a recordkeeping system, and perform operator training. The commenter 
requested a time frame of 12 months rather than 6 months for compliance 
with all the proposed SSM requirements.
    Response: To understand the commenter's concerns better and to 
determine whether a different standard was needed for startup periods, 
the EPA had a teleconference meeting with the commenter to discuss the 
issue. During this discussion, the commenter indicated that the 
facility had found a way to comply with the emissions standards at all 
times, including startup. The notes of the meeting are in the docket 
for this rulemaking (EPA-HQ-OAR-2020-0560). Therefore, with the issue 
resolved, the EPA is finalizing the proposed requirements that the 
emissions limits apply at all times and no separate requirements are 
necessary for periods of startup, and further, no additional time is 
necessary or provided for compliance.
    Comment: One commenter supported electronic reporting in general 
but stated a preference to submit any such information in PDF format.
    Response: Given that the facility could operate for up to 3 more 
years before it converts to a non-mercury process or shut down, we have 
decided

[[Page 27015]]

to require the facility to switch to electronic reporting.
    Comment: One commenter noted that the EPA proposed to add a 
performance testing requirement at 40 CFR 63.8232(a). The commenter 
believes that the annual calibration testing at the facility satisfies 
the requirements of a performance test, and additional performance 
testing is not needed.
    Response: The commenter misinterpreted the proposed changes to 40 
CFR 63.8323(a), which did not add a new performance testing 
requirement. Rather, these proposed changes clarified the conditions 
under which the performance test must be conducted. These changes 
establish that performance tests must be conducted during normal 
operations and remove a reference to 40 CFR 63.7(e)(1), which conflicts 
with the requirement to comply with the standards at all times, 
including during periods of SSM. As these requirements are simply 
clarifying performance test conditions and ensuring the standards are 
met at all times, we are finalizing the revised provisions as proposed.
4. What is the rationale for our final approach for requirements 
related to emissions during periods of startup, shutdown, and 
malfunction and other topics?
    The rationale for our final decision regarding the non-mercury 
option is discussed above in section IV.B.4. As discussed in the 
responses in the previous section, we are finalizing the proposed 
electronic reporting amendments for the reasons described above. 
Furthermore, we have not changed our final approach to the requirements 
for periods of SSM, and we are finalizing these requirements as 
proposed based on the considerations described above.

F. Public Notice and Comments

    In addition to the comments on the proposal, one commenter objected 
to the EPA's decision not to publish the proposed rule amendments in 
the Federal Register.
    Comment: The commenter observed that the EPA proposed significant 
changes to the regulatory language, but these changes were not in the 
EPA's proposed rule. The commenter remarked that the CAA and the 
Administrative Procedures Act (APA) both make plain that proposed rules 
must be published in the Federal Register (42 U.S.C. 7607(d)(3); 5 
U.S.C. 553(b)). Further, the commenter stated that the CAA requires the 
EPA to include a summary of the major legal interpretations and policy 
considerations underlying its proposed rules, and the EPA did not 
provide this explanation nor any explanation for its proposed changes 
to the regulatory text. The commenter states that if the EPA wishes to 
make changes to the Code of Federal Regulations, it must withdraw this 
proposal, publish the proposed changes in the Federal Register and 
provide a new opportunity for public comment.
    Response: The proposal met all APA and CAA notice and comment 
requirements. Nothing in the APA or the CAA, including the language the 
commenter cites, requires the EPA to publish proposed rule text in the 
Federal Register. The commenter suggests that because the EPA did not 
publish the proposed rule text, the EPA failed to meet the CAA 
307(d)(3) requirement to publish a ``notice of proposed rulemaking.'' 
However, the requirement to publish a ``notice of proposed rulemaking'' 
is not a requirement to publish ``proposed rule text.'' Section 
307(d)(3) specifies the required elements of a ``notice of proposed 
rulemaking'' and ``proposed rule text'' is not a required element. The 
elements the commenter cites that are required to be included in the 
notice of proposed rulemaking (a ``statement of basis and purpose,'' 
``a summary of . . . the major legal interpretations and policy 
considerations underlying the proposed rule, etc. . .'') were included, 
and commenter does not suggest otherwise.
    The APA does not require publication of proposed rule text in the 
Federal Register either. Section 553(b)(3) of the APA provides that a 
notice of proposed rulemaking shall include ``either the terms or 
substance of the proposed rule or a description of the subjects and 
issues involved.'' (emphases added). Thus, the APA clearly provides 
flexibility to describe the ``subjects and issues involved'' as an 
alternative to inclusion of the ``terms or substance'' of the proposed 
rule. See also Rybachek v. U.S. E.P.A., 904 F.2d 1276, 1287 (9th Cir. 
1990). (The EPA's failure to propose in advance the actual wording of a 
regulation does not make the regulation invalid where the EPA's 
discussion of the regulatory provisions ``clearly describe `the 
subjects and issues involved.' '').
    The commenter claims that the EPA did not publish ``any explanation 
for its proposed changes''. However, the commenter does not identify 
any specific regulatory text that was not explained or specify any 
deficiency in any explanation of regulatory text in the Federal 
Register document. Such a generalized objection is not sufficiently 
specific. See, e.g., Appalachian Power Co. v. E.P.A., 251 F.3d 1026, 
1036 (D.C. Cir. 2001) (`` `An objection must be made with sufficient 
specificity reasonably to alert the agency.' '' (quoting Tex Tin Corp. 
v. EPA, 935 F.2d 1321, 1323 (D.C. Cir. 1991)).
    The commenter makes a vague assertion that the EPA's approach was 
prejudicial to the ability of the public to be able to find and comment 
on the proposed regulatory changes but does not claim any actual 
difficulty in finding or commenting on the proposed rule language. The 
EPA approach was not prejudicial to the commenter or any member of the 
public. The notice of proposed rulemaking clearly explained that the 
proposed amendatory language and a redline strikeout version of the 
subpart IIIII showing proposed changes were available in the docket and 
on EPA's website: https://www.epa.gov/stationary-sources-air-pollution/mercury-cell-chloralkali-plants-national-emissions-standards.
    The proposed changes to the CFR that would be necessary to 
incorporate the changes proposed in this action are set out in an 
attachment to the memorandum titled Proposed Regulation Edits for 40 
CFR part 63, subpart IIIII, available in the docket for this action 
(EPA-HQ-OAR-2020-0560). The document includes the specific proposed 
amendatory language for revising the CFR and, for the convenience of 
interested parties, a redline version of the regulation.
    Although the EPA's recent practice has generally been to publish 
proposed amendatory regulatory text, the EPA's practice has varied. 
See, e.g., Hazardous Air Pollutants: Proposed Regulations Governing 
Constructed, Reconstructed or Modified Major Sources, 59 FR 15504 
(April 1, 1994) (``The proposed regulatory text is not included in the 
Federal Register document, but is available in Docket No. A-91-64 or by 
request from the EPA contact persons designated earlier in this note. 
The proposed regulatory language is also available on the technology 
Transfer Network (TTN), of EPA's electronic bulletin boards.''); 
Federal Standards for Marine Tank Vessel Loading and Unloading 
Operations and National Emission Standards for Hazardous Air Pollutants 
for Marine Tank Vessel Loading and Unloading Operations, 59 FR 25004 
(May 13, 1994) (``The proposed regulatory text and other materials 
related to this rulemaking are available for review in the docket.''). 
And even when we do include the proposed text in the Federal Register, 
we often include a redline version of proposed regulations in the 
docket for

[[Page 27016]]

rulemakings to assist the public in understanding the proposed 
regulatory changes. In our experience, stakeholders find the redline 
version far more useful than the proposed amendatory language in the 
format required by the Office of the Federal Register. Although 
appropriate for the task of revising the Code of Federal Regulations, 
this language can be difficult to assess without the accompanying full 
regulatory text. Given this and given that we rarely receive comments 
on the proposed amendatory language or on proposed regulatory language 
at all, we determined that for rulemakings such as these, it would be 
more efficient to take the approach here of making both easily 
accessible but not including the proposed amendatory text in the 
document.

V. Summary of Cost, Environmental, and Economic Impacts and Additional 
Analyses Conducted

A. What are the affected facilities?

    There is one facility affected by this action, which is the one 
remaining mercury cell chlor-alkali facility operating in the U.S. This 
facility is located in West Virginia.

B. What are the air quality and other environmental impacts?

    The air quality impacts of this final action will be the 
elimination of approximately 125 pounds of mercury emissions annually. 
In addition to this air quality impact, this action will result in the 
elimination of around 900 pounds of mercury that are released annually 
to other media.
    In addition, it is estimated that the conversion of the remaining 
mercury cell facility to membrane cells will result in an energy 
savings of around 25 percent which results in an estimated cost savings 
of around $1.5 million per year.

C. What are the cost impacts?

    The capital cost of complying with the promulgation of the non-
mercury requirement is estimated to be $69.4 million if the facility 
chooses to convert its mercury unit to a non-mercury process rather 
than rely on its two existing non-mercury units. The total estimated 
annual costs, including the annualized capital costs minus the savings 
realized from the lower electricity needs and the savings related to 
the elimination of the burden of the environmental regulations 
associated with mercury, are $2.7 million per year in 2019 dollars. 
Table 3 presents the estimated annual cost components for conversion 
from mercury cell to membrane cell technology.

  Table 3--Total Annual Cost of Conversion of the West Virginia Mercury
                         Cells to Membrane Cells
                                 [2019$]
------------------------------------------------------------------------
                                                          Annual cost ($/
                  Annual cost component                         yr)
------------------------------------------------------------------------
Capital Recovery........................................      $4,764,982
Mercury Storage.........................................          53,364
Compliance Savings......................................        -546,572
Electricity Savings.....................................      -1,504,893
                                                         ---------------
    Total Annual........................................       2,766,880
------------------------------------------------------------------------

D. What are the economic impacts?

    The net present value of the estimated cost impacts of the final 
amendments to the Mercury Cell Chlor-Alkali NESHAP is $43.0 million, 
discounted at a 7 percent rate to 2020 over a 20-year analytic time 
frame from 2021 to 2040 in 2019 dollars. Using a 3 percent discount 
rate, the net present value of the estimated cost impacts is $39.4 
million. The equivalent annualized value, which is a measure of the 
annualized costs of the final rule consistent with the net present 
value, is $4.0 million and $2.6 million for 7 and 3 percent discount 
rates respectively.
    As stated previously in section B.3., the estimated total annual 
costs are $2.7 million for the Westlake facility. Based on our 
analysis, the estimated annualized costs are only about 0.04 percent of 
the annual revenue of the facility's ultimate parent company in 2020. 
Since the estimated cost impacts are minimal, no significant economic 
impacts to the ultimate parent company nor its consumers are 
anticipated due to the final amendments. For additional details on the 
economic impact analysis please see the memorandum entitled Economic 
Impact Analysis for the Final Mercury Cell Chlor-Alkali National 
Emission Standard for Hazardous Air Pollutants (NESHAP) Beyond-Floor 
Determination and Risk and Technology Review (RTR) available in the 
docket (EPA-HQ-OAR-2020-0560).

E. What are the benefits?

    The EPA anticipates a complete elimination of mercury emissions at 
the one remaining mercury cell chlor-alkali plant as a result of the 
final amendments to the Mercury Cell Chlor-Alkali Plants NESHAP. This 
is estimated to be a reduction of 125 pounds of mercury emitted to the 
atmosphere annually and approximately 900 pounds of mercury released 
annually to other media. EPA has not monetized the health benefits of 
reduced mercury emissions due to this rulemaking due to the lack of 
site specific data and insufficient economic research to support the 
valuation of the health impacts often associated with exposure to 
individual HAP. For the 2022 proposed rule for the Mercury Air Toxics 
Standard (MATS) EPA did develop bounding estimates for the risk and 
associated dollar valuation associated with mercury emitted from U.S. 
Electric Utility Steam Generating Units. These estimates focused on 
exposure of the general population to methylmercury through commercial 
fish consumption and included IQ loss for children exposed in-vitro and 
adult myocardial infarction (MI)-related mortality. These bounding 
estimates are subject to uncertainty which is discussed in the rule 
language.\4\ While the risk assessment conducted for the RTR indicates 
that risks from the source category are already low, future risks from 
this source category will be reduced to zero. Furthermore, as described 
above, this action will eliminate the releases of mercury to the global 
pool from this source.
---------------------------------------------------------------------------

    \4\ National Emission Standards for Hazardous Air Pollutants: 
Coal- and Oil-Fired Electric Utility Steam Generating Units--
Revocation of the 2020 Reconsideration, and Affirmation of the 
Appropriate and Necessary Supplemental Finding; Notice of Proposed 
Rulemaking (87 FR 7624, February 9, 2022).
---------------------------------------------------------------------------

F. What analysis of environmental justice did we conduct?

    Consistent with EPA's commitment to integrating environmental 
justice (EJ) in the agency's actions, and following the directives set 
forth in multiple Executive Orders, the Agency has carefully considered 
the impacts of this action on communities with EJ concerns. For this 
action, we performed a demographic analysis, which is an assessment of 
risks to individual demographic groups of the populations living within 
5 kilometers (km) and within 50 km of the single Mercury Cell Chlor-
Alkali facility associated with this rule. While there are three 
demographic groups (i.e., over age 25 without a high school diploma, 
those below the poverty level, and those aged 65 and up) around this 
facility that are higher than the national average, we find that no one 
is exposed to a cancer risk at or above 1-in-1 million or to a chronic 
noncancer TOSHI greater than 1. As such, the EPA determined that this 
action provides an ample margin of safety to protect public health for 
all populations, including communities already overburdened by 
pollution. Following is a more detailed description of how the agency 
considers

[[Page 27017]]

EJ in the context of regulatory development.
    Executive Order 12898 directs the EPA to identify the populations 
of concern who are most likely to experience unequal burdens from 
environmental harms; specifically, populations of people of color, low-
income populations, and indigenous peoples (59 FR 7629, February 16, 
1994). Additionally, Executive Order 13985 is intended to advance 
racial equity and support underserved communities through federal 
government actions (86 FR 7009, January 20, 2021). Executive Order 
14008 further declares a policy ``to secure environmental justice and 
spur economic opportunity for disadvantaged communities that have been 
historically marginalized overburdened by pollution and under-
investment in housing, transportation, water and wastewater 
infrastructure, and health care'' (86 FR 7619, February 1, 2021). The 
EPA defines EJ as ``the fair treatment and meaningful involvement of 
all people regardless of race, color, national origin, or income with 
respect to the development, implementation, and enforcement of 
environmental laws, regulations, and policies \5\''. The EPA further 
defines the term fair treatment to mean that ``no group of people 
should bear a disproportionate burden of environmental harms and risks, 
including those resulting from the negative environmental consequences 
of industrial, governmental, and commercial operations or programs and 
policies''. In recognizing that people of color and low-income 
populations often bear an unequal burden of environmental harms and 
risks, the EPA continues to consider ways of protecting them from 
adverse public health and environmental effects of air pollution.
---------------------------------------------------------------------------

    \5\ See https://www.epa.gov/environmentaljustice.
---------------------------------------------------------------------------

    To examine the potential for any environmental justice issues that 
might be associated with the source category, we performed a 
demographic analysis, which is an assessment of risks to individual 
demographic groups of the populations living within 5 kilometers (km) 
and within 50 km of the facilities. In the analysis, we evaluated the 
distribution of HAP-related cancer and noncancer risks from the Mercury 
Cell Chlor-Alkali Plants source category across different demographic 
groups within the populations living near facilities.
    As mentioned above, the results of the demographic analysis for the 
source category indicate that three demographic groups included in the 
analysis are higher than the national average in percentage terms 
within 5 km of the facility.\6\ These groups include those over 25 
without a high school diploma (17 percent versus 14 percent 
nationally), those below the poverty level (25 percent versus 14 
percent nationally) and those aged 65 and up (18 percent versus 14 
percent nationally). When examining the risk levels of those exposed to 
emissions from Mercury Cell Chlor-Alkali plants, we determined that no 
one is exposed to a cancer risk at or above 1-in-1 million or to a 
chronic noncancer TOSHI greater than 1. The methodology and the results 
of the demographic analysis are presented in a technical report, Risk 
and Technology Review--Analysis of Demographic Factors for Populations 
Living Near Mercury Cell Chlor-Alkali Plants Source Category 
Operations, which is available in the docket.
---------------------------------------------------------------------------

    \6\ When the demographic analysis was completed in mid-2020, 
there were 2 facilities in the mercury cell chlor-alkali source 
category and both were subject to 40 CFR part 63, subpart IIIII. 
However, in late 2020 one of those facilities converted to a non-
mercury process. Therefore, currently only one facility remains in 
the source category.
---------------------------------------------------------------------------

G. What analysis of children's environmental health did we conduct?

    The EPA does not believe the environmental health or safety risks 
addressed by this action present a disproportionate risk to children. 
The health risk assessments for this action are contained in the 
document titled Residual Risk Assessment for the Mercury Cell Chlor-
Alkali Plants Source Category in Support of the 2021 Risk and 
Technology Review Final Rule, available in the docket (Docket ID No. 
EPA-HQ-OAR-2020-0560).

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.

A. Executive Orders 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is a significant regulatory action that was submitted 
to the Office of Management and Budget (OMB) for review because it 
raises novel legal or policy issues. Any changes made in response to 
OMB recommendations have been documented in the docket.

B. Paperwork Reduction Act (PRA)

    The information collection activities in rule have been submitted 
for approval to OMB under the PRA. The Information Collection Request 
(ICR) document that the EPA prepared has been assigned EPA ICR number 
2046.11. 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 information requirements in this rulemaking are based on the 
notification, recordkeeping, and reporting requirements in the NESHAP 
General Provisions (40 CFR part 63, subpart A), which are mandatory for 
all operators subject to national emission standards. These 
notifications, reports, and records are essential in determining 
compliance, and are specifically authorized by CAA section 114 (42 
U.S.C. 7414). All information submitted to the EPA pursuant to the 
recordkeeping and reporting requirements for which a claim of 
confidentiality is made is safeguarded according to Agency policies set 
forth in 40 CFR part 2, subpart B.
    The EPA is finalizing amendments to eliminate the SSM plan and 
reporting requirements; add requirements for electronic reporting of 
notifications and reports and performance test results; and add a 
reporting requirement for meeting the mercury emissions prohibitions. 
This information will be collected to assure compliance with the 
Mercury Cell Chlor-Alkali Plants NESHAP.
    Respondents/affected entities: The respondents to the recordkeeping 
and reporting requirements are owners or operators of flexible 
polyurethane foam fabrication operations subject to 40 CFR part 63, 
subpart IIIII.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart IIIII).
    Estimated number of respondents: 1 facility.
    Frequency of response: Initially, occasionally, and semi-annually.
    Total estimated burden: 3,567 total hours (per year). Burden is 
defined at 5 CFR 1320.3(b).
    Total estimated cost: $457,200 (per year), includes $29,200 
annualized capital or operation & 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

[[Page 27018]]

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. This 
action will not impose any requirements on small entities. The ultimate 
parent company for the single affected facility in the source category 
is not a small entity given the Small Business Administration small 
business size definition for this industry (1,000 employees or greater 
for NAICS 325180).

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. While this action 
creates an enforceable duty on the private sector, the cost does not 
exceed $100 million or more in any one year.

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. The mercury cell chlor-alkali plant affected by 
this final action is not owned or operated by tribal governments or 
located within tribal lands. Thus, Executive Order 13175 does not apply 
to this action.

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

    This action is not subject to Executive Order 13045 because it is 
not economically significant as defined in Executive Order 12866, and 
because the EPA does not believe the environmental health or safety 
risks addressed by this action present a disproportionate risk to 
children. This action's health and risk assessments are contained in 
section IV.A of this preamble and the document, Residual Risk 
Assessment for the Mercury Cell Chlor-Alkali Plants Source Category in 
Support of the 2021 Risk and Technology Review Final Rule, which is 
available in the docket for this rulemaking.

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. New standards are proposed for 40 CFR 
part 63, subpart IIIII to limit mercury and Cl emissions from mercury 
cell chlor-alkali plants. The proposed limits will have lower 
electricity costs for the one affected facility so it will not have a 
significant adverse effect on the supply, distribution, or use of 
energy.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately 
high and adverse human health or environmental effects on minority 
populations, low-income populations, and/or indigenous peoples, as 
specified in Executive Order 12898 (59 FR 7629, February 16, 1994).
    The documentation for this decision is contained in the technical 
report titled, Risk and Technology Review--Analysis of Demographic 
Factors for Populations Living Near Mercury Cell Chlor-Alkali Plants 
Source Category Operations, available 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 is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 63

    Environmental protection, Administrative practice and procedures, 
Air pollution control, Hazardous substances, Intergovernmental 
relations, Reporting and recordkeeping requirements.

Michael S. Regan,
Administrator.
    For the reasons set out in the preamble, 40 CFR part 63 is amended 
as follows:

PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS 
FOR SOURCE CATEGORIES

0
1. The authority citation for part 63 continues to read as follows:

    Authority:  42 U.S.C. 7401 et seq.


0
2. The heading for subpart IIIII is revised to read as follows:

Subpart IIIII--National Emission Standards for Hazardous Air 
Pollutants for Mercury Cell Chlor-Alkali Plants

0
3. Section 63.8180 is revised to read as follows:


Sec.  63.8180   What is the purpose of this subpart?

    This subpart establishes national emission standards for hazardous 
air pollutants (NESHAP) for affected sources at mercury cell chlor-
alkali plants. This subpart also establishes requirements to 
demonstrate initial and continuous compliance with all applicable 
emission limitations and work practice standards in this subpart.

0
4. Section 63.8182 is amended by revising paragraph (c) introductory 
text to read as follows:


Sec.  63.8182   Am I subject to this subpart?

* * * * *
    (c) Beginning on December 19, 2006, the provisions of subpart E of 
40 CFR part 61 that apply to mercury cell chlor-alkali plants, which 
are listed in paragraphs (c)(1) through (3) of this section, are no 
longer applicable.
* * * * *

0
5. Section 63.8184 is amended by revising paragraphs (a)(1) and (2) to 
read as follows:


Sec.  63.8184   What parts of my plant does this subpart cover?

    (a) * * *
    (1) The mercury cell chlor-alkali production facility designates an 
affected source consisting of all cell rooms and ancillary operations 
used in the manufacture of product chlorine, product caustic, and by-
product hydrogen at a plant site. This subpart covers mercury emissions 
from by-product hydrogen streams and end box ventilation system vents, 
mercury fugitive emissions associated with cell rooms, hydrogen 
systems, caustic systems, and storage areas for mercury-containing 
wastes; and chlorine fugitive emissions associated with the mercury 
cell chlor-alkali production facility.
    (2) The mercury recovery facility designates an affected source 
consisting of all processes and associated operations needed for 
mercury recovery

[[Page 27019]]

from wastes at a plant site. This subpart covers mercury emissions from 
mercury thermal recovery unit vents and fugitive emission sources of 
mercury associated with storage areas for mercury-containing wastes.
* * * * *

0
6. Section 63.8186 is amended by revising paragraph (a) to read as 
follows:


Sec.  63.8186   When do I have to comply with this subpart?

    (a) If you have an existing affected source, you must comply 
according to the dates specified in paragraphs (a)(1) through (5) of 
this section, as applicable.
    (1) You must comply with each emission limitation, each work 
practice standard specified in paragraphs Sec.  63.8192(a) through (f) 
or each work practice standard in paragraphs Sec.  63.8192(e) through 
(g), and with each recordkeeping and reporting requirement in this 
subpart that applies to you by December 19, 2006, except as specified 
in paragraphs (a)(2) through (5) of this section.
    (2) You must comply with each work practice standard in Sec.  
63.8192(a) through (c) and (e) through (h) and the electronic reporting 
requirements in Sec.  63.8232(g), Sec.  63.8252(g), and Sec.  
63.8254(e) by November 7, 2022.
    (3) Until November 7, 2022, you must comply with the requirements 
in Sec.  63.8226(a) and the requirements specified in the startup, 
shutdown, and malfunction plan required at Sec.  63.8226(b).
    (4) On and after November 7, 2022, you must comply with the 
applicable requirements in paragraph Sec.  63.8226(c).
    (5) On and after May 6, 2025, you must comply with the emission 
limitations in Sec.  63.8190(a)(2)(ii) and the notification requirement 
in Sec.  63.8252(h).
* * * * *

0
7. Section 63.8190 is amended by revising paragraph (a)(2) to read as 
follows:


Sec.  63.8190   What emission limitations must I meet?

    (a) * * *
    (2) Existing mercury cell chlor-alkali production facility. Until 
the compliance date listed in Sec.  63.8186(a)(5), you must comply with 
paragraph (a)(2)(i) of this section. On and after the compliance date 
listed in Sec.  63.8186(a)(5), you must comply with paragraph 
(a)(2)(ii) of this section.
    (i) During any consecutive 52-week period, you must not discharge 
to the atmosphere total mercury emissions in excess of the applicable 
limit in paragraph (a)(2)(i)(A) or (B) of this section calculated using 
the procedures in Sec.  63.8243(a).
    (A) 0.076 grams of mercury per megagram of chlorine produced (1.5 x 
10-4 pounds of mercury per ton of chlorine produced) from 
all by-product hydrogen streams and all end box ventilation system 
vents when both types of emission points are present.
    (B) 0.033 grams of mercury per megagram of chlorine produced (6.59 
x 10-5 pounds of mercury per ton of chlorine produced) from 
all by-product hydrogen streams when end box ventilation systems are 
not present.
    (ii) Emissions of mercury are prohibited from an existing mercury 
cell chlor-alkali production facility.
* * * * *

0
8. Section 63.8192 is amended by revising the introductory text, 
paragraph (a), and paragraph (g) introductory text, and adding 
paragraph (h) to read as follows:


Sec.  63.8192   What work practice standards must I meet?

    In accordance with the compliance dates specified in Sec.  
63.8186(a)(1), you must meet the work practice requirements specified 
in paragraphs (a) through (f) of this section. As an alternative to the 
requirements specified in paragraphs (a) through (d) of this section, 
you may choose to comply with paragraph (g) of this section. On and 
after the compliance date specified in Sec.  63.8186(a)(2) and until 
the compliance date specified in Sec.  63.8186(a)(5), you must meet the 
work practice requirements specified in paragraphs (a) through (c) and 
(e) through (h) of this section.
    (a) You must meet the work practice standards in Tables 1 through 4 
to this subpart.
* * * * *
    (g) You must institute a cell room monitoring program to 
continuously monitor the mercury vapor concentration in the upper 
portion of each cell room and to take corrective actions as quickly as 
possible when elevated mercury vapor levels are detected. As specified 
in Sec.  63.8252(e)(1)(iv), you must prepare and submit to the 
Administrator, a cell room monitoring plan containing the elements 
listed in Table 5 to this subpart and meet the requirements in 
paragraphs (g)(1) through (4) of this section.
* * * * *
    (h) You must comply with the requirements specified in paragraphs 
(h)(1) through (4) of this section to reduce fugitive chlorine 
emissions in the mercury cell chlor-alkali production facility affected 
source.
    (1) You must identify each piece of equipment located throughout 
the mercury cell chlor-alkali production facility affected source that 
contains chlorine gas at a concentration of at least 5 percent by 
volume. You may identify equipment by a list or on a process or piping 
diagram. You may exclude equipment that is under negative pressure.
    (2) You must install ambient chlorine sensors at the mercury cell 
chlor-alkali production facility affected source to measure the ambient 
chlorine concentration.
    (i) Ambient chlorine sensors must have a detection limit of 0.5 
ppmv or less.
    (ii) The sensors must be operated continuously to obtain a 
measurement at least once each 15 minutes.
    (iii) You must identify the location of the sensors by a list or on 
a process or piping diagram.
    (iv) You must operate, calibrate, and maintain these sensors in 
accordance with manufacturer instructions.
    (v) You must keep the necessary parts for routine repairs of the 
sensors readily available.
    (3) You must perform inspections to identify leaks of chlorine 
using olfactory observations according to the schedules in paragraphs 
(h)(3)(i) and (ii) of this section. A leak is detected when there is an 
olfactory observation of a leak. If a leak is detected, you must comply 
with the repair provisions in paragraph (h)(4) of this section.
    (i) At least once each 12 hours, you must inspect each piece of 
equipment located throughout the mercury cell chlor-alkali production 
facility affected source that contains chlorine gas at a concentration 
of greater than 5 percent by volume for chlorine leaks, excluding 
equipment that is under negative pressure.
    (ii) Within 1 hour of detection of a 1-hour average chlorine 
concentration of 2 ppmv or greater by a sensor installed and operated 
in accordance with paragraph (h)(2) of this section, you must inspect 
each piece of equipment located throughout the mercury cell chlor-
alkali production facility affected source that contains chlorine gas 
at a concentration of greater than 5 percent by volume for chlorine 
leaks, excluding equipment that is under negative pressure.
    (4) You must undertake a first attempt at repair no later than 1 
hour after the leak is detected, and the leak must be repaired no later 
than 72 hours after the leak is detected. A leak is repaired when there 
is no olfactory observation of a leak.

[[Page 27020]]


0
9. Section 63.8222 is revised to read as follows:


Sec.  63.8222   What are my operation and maintenance requirements?

    At all times you must operate and maintain any affected source, 
including associated air pollution control equipment and monitoring 
equipment, in a manner consistent with safety and good air pollution 
control practices for minimizing emissions. The general duty to 
minimize emissions does not require you to make any further efforts to 
reduce emissions if levels required by the applicable standards have 
been achieved. Determination of whether a source is operating in 
compliance with operation and maintenance requirements will be based on 
information available to the Administrator which may include, but is 
not limited to, monitoring results, review of operation and maintenance 
procedures, review of operation and maintenance records, reports and 
inspection of the source.

0
10. Section 63.8226 is revised to read as follows:


Sec.  63.8226   What are my general requirements for complying with 
this subpart?

    (a) Until November 7, 2022, you must be in compliance with the 
applicable emission limitations in Sec.  63.8190 and the applicable 
work practice standards in Sec.  63.8192 at all times, except during 
periods of startup, shutdown, and malfunction.
    (b) Until November 7, 2022, you must develop and operate as 
specified by a written startup, shutdown, and malfunction plan (SSMP) 
according to the provisions in Sec.  63.6(e)(3).
    (c) On and after November 7, 2022, the provisions of paragraphs (a) 
and (b) of this section no longer apply, and you must be in compliance 
with the applicable emission limitations in Sec.  63.8190 and the 
applicable work practice standards in Sec.  63.8192 at all times.

0
11. Section 63.8232 is amended by revising the introductory text and 
paragraph (a) and adding paragraph (g) to read as follows:


Sec.  63.8232   What test methods and other procedures must I use to 
demonstrate initial compliance with the emission limits?

    You must conduct a performance test for each by-product hydrogen 
stream, end box ventilation system vent, and mercury thermal recovery 
unit vent according to the conditions detailed in paragraphs (a) 
through (d) of this section.
    (a) You must conduct each performance test under conditions 
representative of normal operations. You may not conduct performance 
tests during periods of startup, shutdown, or malfunction. You must 
record the process information that is necessary to document operating 
conditions during the test and include in such record an explanation to 
support that such conditions represent normal operation. Upon request, 
you shall make available to the Administrator such records as may be 
necessary to determine the conditions of performance tests.
* * * * *
    (g) Within 60 days after the date of completing each performance 
test specified in this section, you must submit the results of the 
performance test following the procedures specified in paragraphs 
(g)(1) through (3) of this section.
    (1) Data collected using test methods supported by the EPA's 
Electronic Reporting Tool (ERT) as listed on the EPA's ERT website 
(https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert) at the time of the test. Submit the results of the 
performance test to the EPA via the Compliance and Emissions Data 
Reporting Interface (CEDRI), which can be accessed through the EPA's 
Central Data Exchange (CDX) (https://cdx.epa.gov/). The data must be 
submitted in a file format generated using the EPA's ERT. 
Alternatively, you may submit an electronic file consistent with the 
extensible markup language (XML) schema listed on the EPA's ERT 
website.
    (2) Data collected using test methods that are not supported by the 
EPA's ERT as listed on the EPA's ERT website at the time of the test. 
The results of the performance test must be included as an attachment 
in the ERT or an alternate electronic file consistent with the XML 
schema listed on the EPA's ERT website. Submit the ERT generated 
package or alternative file to the EPA via CEDRI.
    (3) Confidential business information (CBI). Do not use CEDRI to 
submit information you claim as CBI. Anything submitted using CEDRI 
cannot later be claimed CBI. Although we do not expect persons to 
assert a claim of CBI, if you wish to assert a CBI claim for some of 
the information submitted under paragraph (g)(1) or (2) of this 
section, you must submit a complete file, including information claimed 
to be CBI, to the EPA. The file must be generated using the EPA's ERT 
or an alternate electronic file consistent with the XML schema listed 
on the EPA's ERT website. Submit the file on a compact disc, flash 
drive, or other commonly used electronic storage medium and clearly 
mark the medium as CBI. Mail the electronic medium to U.S. EPA/OAQPS/
CORE CBI Office, Attention: Group Leader, Measurement Policy Group, MD 
C404-02, 4930 Old Page Rd., Durham, NC 27703. The same file with the 
CBI omitted must be submitted to the EPA via the EPA's CDX as described 
in paragraphs (g)(1) and (2) of this section. All CBI claims must be 
asserted at the time of submission. Furthermore, under CAA section 
114(c), emissions data is not entitled to confidential treatment, and 
the EPA is required to make emissions data available to the public. 
Thus, emissions data will not be protected as CBI and will be made 
publicly available.

0
12. Section 63.8236 is amended by revising paragraph (c) introductory 
text and adding paragraphs (e) and (f) to read as follows:


Sec.  63.8236   How do I demonstrate initial compliance with the 
emission limitations and work practice standards?

* * * * *
    (c) Prior to the compliance date specified in Sec.  63.8186(a)(2), 
for each affected source, you have demonstrated initial compliance with 
the applicable work practice standards in Sec.  63.8192 if you comply 
with paragraphs (c)(1) through (7) of this section.
* * * * *
    (e) On and after the compliance date specified in Sec.  
63.8186(a)(2), for each affected source, you have demonstrated initial 
compliance with the applicable work practice standards for mercury 
emissions in Sec.  63.8192(a) through (c) and (e) through (g) if you 
comply with paragraphs (e)(1) through (4) of this section.
    (1) You have submitted a Revised Notification of Compliance Status 
containing the results of the initial compliance demonstration 
according to the requirements in Sec.  63.8252(f).
    (2) You certify in your Revised Notification of Compliance Status 
that you are operating according to the work practice standards for 
mercury emissions in Sec.  63.8192(a) through (c), (e), and (f).
    (3) You have submitted your cell room monitoring plan as part of 
your Revised Work Practice Notification of Compliance Status and you 
certify in your Revised Notification of Compliance Status that you are 
operating according to the continuous cell room monitoring program 
under Sec.  63.8192(g).
    (4) You have re-submitted your washdown plan as part of your 
Revised Notification of Compliance Status and you re-certify in your 
Revised

[[Page 27021]]

Notification of Compliance Status that you are operating according to 
your washdown plan under Sec.  63.8192(e).
    (f) On and after the compliance date specified in Sec.  
63.8186(a)(2), for each affected source, you have demonstrated initial 
compliance with the applicable work practice standards for chlorine 
emissions in Sec.  63.8192(h) if you meet the requirements of 
paragraphs (f)(1) through (3) of this section.
    (1) You have installed chlorine sensors in accordance with Sec.  
63.8192(h)(2).
    (2) You have certified in your Revised Notification of Compliance 
Status that you are operating according to the work practice standards 
in Sec.  63.8192(h).
    (3) You have submitted your Revised Notification of Compliance 
Status containing the results of the initial compliance demonstration 
according to the requirements in Sec.  63.8252(f).

0
13. Section 63.8242 is amended by revising the section heading and 
paragraphs (a)(2) and (a)(3)(v) to read as follows:


Sec.  63.8242   What are the installation, operation, and maintenance 
requirements for my continuous mercury monitoring systems?

    (a) * * *
    (2) Each mercury continuous emissions monitor analyzer must have a 
detector with the capability to detect a mercury concentration of 
either 0.1 [mu]g/m\3\ or 0.5 times the mercury concentration level 
measured during the performance test conducted according to Sec.  
63.8232.
    (3) * * *
    (v) Ongoing data quality assurance procedures according to the 
requirements of Sec.  63.8(d)(1) and (2). You shall keep these written 
procedures on record for the life of the affected source or until the 
affected source is no longer subject to the provisions of this part, to 
be made available for inspection, upon request, by the Administrator. 
If the performance evaluation plan is revised, you shall keep previous 
(i.e., superseded) versions of the performance evaluation plan on 
record to be made available for inspection, upon request, by the 
Administrator, for a period of 5 years after each revision to the plan. 
The program of corrective action shall be included in the plan required 
under Sec.  63.8(d)(2).
* * * * *

0
14. Section 63.8246 is amended by revising paragraphs (b)(1) 
introductory text and (c) and adding paragraph (d) to read as follows:


Sec.  63.8246   How do I demonstrate continuous compliance with the 
emission limitations and work practice standards?

* * * * *
    (b) * * *
    (1) For each mercury thermal recovery unit vent, you must 
demonstrate continuous compliance with the applicable emission limit 
specified in Sec.  63.8190(a)(3) by maintaining the outlet mercury 
daily-average concentration no higher than the applicable limit. To 
determine the outlet mercury concentration, you must monitor according 
to paragraph (b)(1)(i) or (ii) of this section.
* * * * *
    (c) You must demonstrate continuous compliance with the applicable 
work practice standards for mercury emissions in Sec.  63.8192 by 
maintaining records in accordance with Sec.  63.8256(c) and (e).
    (d) You must demonstrate continuous compliance with the applicable 
work practice standards for chlorine emissions in Sec.  63.8192(h) by 
continuously operating the chlorine sensors required by Sec.  
63.8192(h)(2), inspecting equipment in accordance with Sec.  
63.8192(h)(3), repairing equipment in accordance with Sec.  
63.8192(h)(4) and maintaining records in accordance with Sec.  
63.8256(f).

0
15. Section 63.8248 is amended by revising paragraphs (a) introductory 
text, (a)(1) and (2), and (2), and adding paragraph (b) introductory 
text to read as follows:


Sec.  63.8248   What other requirements must I meet?

    (a) Deviations. The instances specified in paragraphs (a)(1) 
through (4) of this section are deviations and must be reported 
according to the requirements in Sec.  63.8254 and recorded according 
to the requirements in Sec.  63.8256(a)(2).
    (1) You must report each instance in which you did not meet each 
emission limitation in Sec.  63.8190 that applies to you.
    (2) You must report each instance in which you did not meet each 
work practice standard in Sec.  63.8192 that applies to you.
* * * * *
    (b) * * * The provisions of paragraphs (b)(1) through (3) of this 
section apply until November 7, 2022. On and after November 7, 2022, 
the provisions of paragraphs (b)(1) through (3) of this section no 
longer apply.
* * * * *

0
16. Section 63.8252 is amended by revising paragraphs (d) and (e)(1)(i) 
and adding paragraphs (f) through (h) to read as follows:


Sec.  63.8252   What notifications must I submit and when?

* * * * *
    (d) For each performance test that you are required to conduct for 
by-product hydrogen streams and end box ventilation system vents and 
for mercury thermal recovery unit vents, you must submit a notification 
of intent to conduct a performance test at least 60 calendar days 
before the performance test is scheduled to begin as required in Sec.  
63.7(b)(1).
    (e) * * *
    (1) * * *
    (i) If you choose not to implement a cell room monitoring program 
according to Sec.  63.8192(g), a certification that you are operating 
according to the applicable work practice standards for mercury 
emissions in Sec.  63.8192(a) through (d) and your floor-level mercury 
vapor measurement plan required by Sec.  63.8192(d).
* * * * *
    (f) You must submit a Revised Notification of Compliance Status 
before the close of business on the date 30 days after the compliance 
date in Sec.  63.8186(a)(2) containing the items in paragraphs (f)(1) 
through (5) of this section:
    (1) A certification that you are operating according to the work 
practice standards for mercury emissions in Sec.  63.8192(a) through 
(c) and (e) through (g).
    (2) Your cell room monitoring plan, including your initial action 
level determined in accordance with Sec.  63.8192(g)(2), and a 
certification that you are operating according to the continuous cell 
room monitoring program under Sec.  63.8192(g).
    (3) Your washdown plan, and a certification that you are operating 
according to your washdown plan under Sec.  63.8192(e).
    (4) Records of the mass of virgin mercury added to cells for every 
year since 2001.
    (5) A certification that you have installed chlorine sensors in 
accordance with Sec.  63.8192(h)(2) and that you are operating 
according to the work practice standards for chlorine emissions in 
Sec.  63.8192(h).
    (g) You must submit all subsequent Notification of Compliance 
Status reports and Revised Notification of Compliance Status reports in 
PDF format to the EPA via CEDRI, which can be accessed through EPA's 
CDX (https://cdx.epa.gov/).
    (h) You must submit a notification of compliance with the 
prohibition of mercury emissions as specified in paragraphs (e)(1) and 
(2) of this section.

[[Page 27022]]

    (1) The notification must include the information specified in 
paragraph (e)(1)(i) and (ii) of this section.
    (i) A certification that the requirement of Sec.  63.8190(a)(2)(ii) 
has been met.
    (ii) A brief explanation of how the requirement of Sec.  
63.8190(a)(2)(ii) has been met.
    (2) You must submit this notification before the close of business 
on the 30th calendar day following the date when compliance with Sec.  
63.8190(a)(2)(ii) is attained.

0
17. Section 63.8254 is amended by:
0
a. Revising paragraph (b) introductory text;
0
b. Removing and reserving paragraph (b)(4);
0
c. Revising paragraphs (b)(7) through (9);
0
d. Adding paragraphs (b)(13) and (14);
0
e. Removing and reserving paragraph (c); and
0
f. Adding paragraph (e).
    The revisions and additions read as follows:


Sec.  63.8254   What reports must I submit and when?

* * * * *
    (b) Compliance report contents. Each compliance report must contain 
the information in paragraphs (b)(1) through (3) of this section, and 
as applicable, paragraphs (b)(5) through (13) of this section.
* * * * *
    (7) For each deviation from the requirements for work practice 
standards in Sec.  63.8192, the information in paragraphs (b)(7)(i) and 
(ii) of this section.
    (i) For each deviation from the mercury work practice standards in 
Tables 1 through 4 to this subpart that occurs at an affected source 
(including deviations where the response intervals were not adhered to 
as described in Sec.  63.8192(b)), each deviation from the cell room 
monitoring program monitoring and data recording requirements in Sec.  
63.8192(g)(3), and each deviation from the response intervals required 
by Sec.  63.8192(g)(4) when an action level is exceeded, the compliance 
report must contain the information in paragraphs (b)(1) through (3) of 
this section and the information in paragraphs (b)(7)(i)(A) through (C) 
of this section.
    (A) The total operating time of each affected source during the 
reporting period.
    (B) Information on the number, date, time, duration, and cause of 
deviations (including unknown cause, if applicable), as applicable, and 
the corrective action taken.
    (C) A list of the affected sources or equipment.
    (ii) For each deviation from the fugitive chlorine requirements in 
Sec.  63.8192(h), including periods when the chlorine sensors required 
by Sec.  63.8192(h)(2) were not operating; instances where the chlorine 
sensors required by Sec.  63.8192(h)(2) were not calibrated and 
maintained in accordance with manufacturer instructions or spare parts 
were not maintained; instances where inspections were not performed in 
accordance with Sec.  63.8192(h)(3)(i) and (ii); and instances where 
leak repair intervals in Sec.  63.8192(h)(4) were not met; the 
compliance report must contain the information in paragraphs (b)(1) 
through (3) of this section and the information in paragraphs 
(b)(7)(ii)(A) through (C) of this section.
    (A) The total operating time of each affected source during the 
reporting period.
    (B) Information on the number, date, time, duration, and cause of 
deviations (including unknown cause, if applicable), as applicable, and 
the corrective action taken.
    (C) A list of the affected sources or equipment.
    (8) For each deviation from an emission limitation occurring at an 
affected source where you are using a mercury continuous emission 
monitor, according to the site-specific monitoring plan required in 
Sec.  63.8242(a)(3), to comply with the emission limitation in this 
subpart, you must include the information in paragraphs (b)(1) through 
(3) of this section and the information in paragraphs (b)(8)(i) through 
(xv) of this section.
    (i) A list of the affected sources and equipment.
    (ii) The date and time that each deviation started and stopped.
    (iii) For each deviation, the cause of the deviation (including 
unknown cause, if applicable), as applicable, and corrective action 
taken.
    (iv) For each deviation, an estimate of the quantity of each 
regulated pollutant emitted over any emission limit.
    (v) A description of the method used to estimate the emissions.
    (vi) The date and time of each instance in which a continuous 
monitoring system was inoperative, except for zero (low-level) and 
high-level checks.
    (vii) The date, time, and duration of each instance in which a 
continuous monitoring system was out-of-control, including the 
information in Sec.  63.8(c)(8).
    (viii) A summary of the total duration of the deviation during the 
reporting period and the total duration as a percent of the total 
source operating time during that reporting period.
    (ix) A breakdown of the total duration of the deviations during the 
reporting period including those that are due to control equipment 
problems, process problems, other known causes, and other unknown 
causes.
    (x) A summary of the total duration of continuous monitoring system 
downtime during the reporting period and the total duration of 
monitoring system downtime as a percent of the total source operating 
time during the reporting period.
    (xi) An identification of each hazardous air pollutant that was 
monitored at the affected source.
    (xii) A brief description of the process units.
    (xiii) A brief description of the continuous monitoring system.
    (xiv) The date of the latest continuous monitoring system 
certification or audit.
    (xv) A description of any changes in monitoring system, processes, 
or controls since the last reporting period.
    (9) For each deviation from an operation and maintenance standard 
occurring at an affected source where you are using the periodic 
monitoring option specified in Sec.  63.8240(b) and your final control 
device is not a nonregenerable carbon adsorber, the compliance report 
must include the information in paragraphs (b)(1) through (3) of this 
section and the information in paragraphs (b)(9)(i) through (xiii) of 
this section.
    (i) A list of the affected sources or equipment.
    (ii) The total operating time of each affected source during the 
reporting period.
    (iii) Information on the number, duration, and cause of deviations 
(including unknown cause, if applicable), as applicable, and the 
corrective action taken.
    (iv) For each deviation, an estimate of the quantity of each 
regulated pollutant emitted over any emission limit.
    (v) A description of the method used to estimate the emissions.
    (vi) The date and time of each instance in which a CPMS was 
inoperative, except for zero (low-level) and high-level checks.
    (vii) The date, time, and duration of each instance in which a CPMS 
was out-of-control, including the information specified in Sec.  
63.8(c)(8).
    (viii) A summary of the total duration of the deviation during the 
reporting period and the total duration as a percent of the total 
source operating time during that reporting period.
    (ix) A breakdown of the total duration of the deviations during the 
reporting

[[Page 27023]]

period including those that are due to control equipment problems, 
process problems, other known causes, and other unknown causes.
    (x) A summary of the total duration of continuous monitoring system 
downtime during the reporting period and the total duration of 
monitoring system downtime as a percent of the total source operating 
time during the reporting period.
    (xi) A brief description of the CPMS.
    (xii) The date of the latest CPMS certification or audit.
    (xiii) A description of any changes in monitoring system, 
processes, or controls since the last reporting period.
* * * * *
    (13) The compliance report must contain the information specified 
in paragraphs (b)(13)(i) through (iii) for each instance where the 1-
hour average concentration of chlorine detected by a chlorine sensor 
required by Sec.  63.8192(h)(2) was 2 ppmv or greater.
    (i) The date and times a chlorine sensor detected chlorine 
concentrations of 2 ppmv or greater.
    (ii) The location of the sensor.
    (iii) The date and time that the sensor returned to a 1-hour 
average concentration of less than 2 ppmv.
    (14) The compliance report must contain the information specified 
in paragraphs (b)(14)(i) and (ii) for all inspections conducted under 
either Sec.  63.8192(h)(3)(i) or (ii). You must also record the 
information in paragraphs (b)(14)(iii) through (vii) of this section 
for each leak identified.
    (i) The date of each inspection.
    (ii) The reason for each inspection (i.e., a routine inspection 
conducted each 12 hours or an inspection conducted in response to a 2 
ppmv or greater 1-hour average concentration of chlorine, as detected 
by a sensor).
    (iii) Location of the leak.
    (iv) Date and time the leak was identified.
    (v) Date and time of initial repair attempt.
    (vi) Date and time the leak is repaired.
    (vii) A description of the repair made to stop the leak.
* * * * *
    (e) The owner or operator must submit semiannual compliance reports 
in PDF formatto the EPA viaCEDRI, which can be accessedthrough EPA's 
CDX (https://cdx.epa.gov/).

0
18. Section 63.8256 is amended by revising paragraphs (a)(2) and (c) 
introductory text and adding paragraphs (e) and (f) to read as follows:


Sec.  63.8256   What records must I keep?

    (a) * * *
    (2) The records specified in paragraphs (a)(2)(i) and (ii) of this 
section related to deviations.
    (i) Record actions taken to minimize emissions in accordance with 
Sec.  63.8222 and any corrective actions taken to return the affected 
unit to its normal or usual manner of operation.
    (ii) Records of the information reported as required in Sec.  
63.8254(b)(7) through (9) and (11) through (13).
* * * * *
    (c) Records associated with the work practice standards for mercury 
emissions that must be kept prior to the compliance date in Sec.  
63.8186(a)(2).
* * * * *
    (e) Records associated with the work practice standards for mercury 
emissions that must be kept after the compliance date in Sec.  
63.8186(a)(2).
    (1) The records specified in Table 9 to this subpart related to the 
work practice standards in Tables 1 through 4 of this subpart.
    (2) You must maintain a copy of your current washdown plan and 
records of when each washdown occurs.
    (3) You must maintain records of the mass of virgin mercury added 
to cells for each reporting period.
    (4) You must keep your current cell room monitoring plan and the 
records specified in paragraphs (e)(4)(i) through (v) of this section.
    (i) Records of the monitoring conducted in accordance with Sec.  
63.8192(g)(2)(i) to establish your action level, and records 
demonstrating the development of this action level.
    (ii) Records of the cell room mercury concentration monitoring data 
collected.
    (iii) Instances when the action level is exceeded.
    (iv) Records specified in Sec.  63.8192(g)(4)(i) for maintenance 
activities that cause the mercury vapor concentration to exceed the 
action level.
    (v) Records of all inspections and corrective actions taken in 
response to a non-maintenance related situation in which the mercury 
vapor concentration exceeds the action level.
    (f) You must keep the records specified in paragraphs (f)(1) 
through (4) of this section associated with the work practice standards 
for fugitive chlorine emissions specified in Sec.  63.8192(h) after the 
compliance date in Sec.  63.8186(a)(2).
    (1) Identification of all equipment in the mercury cell chlor-
alkali production facility affected source containing chlorine gas at a 
concentration of greater than 5 percent by volume. You may exclude 
equipment that is under negative pressure.
    (2) Records of the information reported as required in Sec.  
63.8254(b)(13) and (14).
    (3) You must record the information specified in paragraphs 
(f)(3)(i) through (iv) of this section for the chlorine sensors 
required by Sec.  63.8192(h)(2).
    (i) The location, manufacturer, and model number of each sensor.
    (ii) The manufacturer's instructions for operation, maintenance, 
and calibration of the chlorine sensors.
    (iii) Records of all maintenance and calibration of the chlorine 
sensors.
    (iv) You must record all periods when the chlorine sensors are not 
operating.
    (4) You must maintain records of all chlorine concentration 
measurements.

0
19. Section 63.8262 is revised to read as follows:


Sec.  63.8262   What parts of the General Provisions apply to me?

    Table 10 to this subpart shows which parts of the General 
Provisions in Sec. Sec.  63.1 through 63.13 apply to you.

0
20. Section 63.8264 is amended by revising paragraph (c) introductory 
text and adding paragraph (c)(5) to read as follows:


Sec.  63.8264   Who implements and enforces this subpart?

* * * * *
    (c) The authorities in paragraphs (c)(1) through (5) of this 
section will not be delegated to State, local, or tribal agencies.
* * * * *
    (5) Approval of an alternative to any electronic reporting to the 
EPA required by this subpart.

0
21. Section 63.8266 is amended by revising the definition of 
``Deviation'' to read as follows:


Sec.  63.8266   What definitions apply to this subpart?

* * * * *
    Deviation means any instance in which an affected source subject to 
this subpart, or an owner or operator of such a source:
    (1) Fails to meet any requirement or obligation established by this 
subpart including, but not limited to, any emission limitation 
(including any operating limit) or work practice standard (including 
any monitoring plan);
    (2) Fails to meet any term or condition that is adopted to 
implement an applicable requirement in this subpart and that is 
included in the title V operating permit for any affected source 
required to obtain such a permit; or
    (3) Fails to take corrective actions within 48 hours that result in 
parameter monitoring values being within range.
* * * * *

[[Page 27024]]


0
22. Table 5 to subpart IIIII of part 63 is amended by revising the 
introductory text to read as follows:

Table 5 to Subpart IIIII of Part 63--Required Elements of Floor-Level 
Mercury Vapor Measurement and Cell Room Monitoring Plans

    Your Floor-Level Mercury Vapor Measurement Plan required by Sec.  
63.8192(d) prior to the applicable compliance date specified in Sec.  
63.8186(a)(2) and Cell Room Monitoring Plan required by Sec.  
63.8192(g) must contain the elements listed in the following table:
* * * * *

0
23. Table 10 to subpart IIIII of part 63 is revised to read as follows:

Table 10 to Subpart IIIII of Part 63--Applicability of General 
Provisions to Subpart IIIII

    As stated in Sec.  63.8262, you must comply with the applicable 
General Provisions requirements according to the following table:

----------------------------------------------------------------------------------------------------------------
                                                                Applies to subpart
              Citation                        Subject                  IIIII                 Explanation
----------------------------------------------------------------------------------------------------------------
Sec.   63.1.........................  Applicability..........  Yes.................
Sec.   63.2.........................  Definitions............  Yes.................
Sec.   63.3.........................  Units and Abbreviations  Yes.................
Sec.   63.4.........................  Prohibited Activities..  Yes.................
Sec.   63.5.........................  Construction/            Yes.................
                                       Reconstruction.
Sec.   63.6(a)-(g), (i), (j), except  Compliance with          Yes.................
 for (e)(1)(i) and (ii), (e)(3), and   Standards and
 (f)(1).                               Maintenance
                                       Requirements.
Sec.   63.6(e)(1)(i) and (ii),        SSM Requirements.......  Yes.................  Only applies until the date
 (e)(3), and (f)(1).                                                                  specified in Sec.
                                                                                      63.8186(a)(3).
Sec.   63.6(h)......................  Compliance with Opacity  No..................  Subpart IIIII does not have
                                       and Visible Emission                           opacity and visible
                                       Standards.                                     emission standards.
Sec.   63.7(a)-(h), except for        Performance Testing      Yes.................  Subpart IIIII specifies
 (a)(2) and (e)(1).                    Requirements.                                  additional requirements
                                                                                      related to site-specific
                                                                                      test plans and the conduct
                                                                                      of performance tests.
Sec.   63.7(a)(2)...................  Applicability and        No..................  Subpart IIIII requires the
                                       Performance Test Dates.                        performance test to be
                                                                                      performed on the
                                                                                      compliance date.
Sec.   63.7(e)(1)...................  Performance Test         No..................  See Sec.   63.8232(a).
                                       Conditions.
Sec.   63.8(a)(1), (a)(3); (b);       Monitoring Requirements  Yes.................  Only applies for CEMS,
 (c)(1)(ii), (2)-(4), (6)-(8);                                                        except Subpart IIIII
 (d)(1)-(2); (e); and (f)(1)-(5).                                                     specifies how and when the
                                                                                      performance evaluation
                                                                                      results are reported.
Sec.   63.8(a)(2)...................  Continuous Monitoring    No..................  Subpart IIIII requires a
                                       System (CMS)                                   site-specific monitoring
                                       Requirements.                                  plan in lieu of a
                                                                                      promulgated performance
                                                                                      specification for a
                                                                                      mercury concentration CMS.
Sec.   63.8(a)(4)...................  Additional Monitoring    No..................  Subpart IIIII does not
                                       Requirements for                               require flares.
                                       Control Devices in
                                       Sec.   63.11.
Sec.   63.8(c)(1)(i) and (iii)......  CMS Operation and SSM    Yes.................  Only applies until the date
                                       Plan.                                          specified in Sec.
                                                                                      63.8186(a)(3).
Sec.   63.8(c)(5)...................  COMS Minimum Procedures  No..................  Subpart IIIII does not have
                                                                                      opacity and visible
                                                                                      emission standards.
Sec.   63.8(d)(3)...................  Written Procedures for   No..................  See Sec.
                                       CMS.                                           63.8242(a)(3)(v).
Sec.   63.8(f)(6)...................  Alternative to Relative  No..................  Subpart IIIII does not
                                       Accuracy Test.                                 require CEMS.
Sec.   63.8(g)......................  Data Reduction.........  No..................  Subpart IIIII specifies
                                                                                      mercury concentration CMS
                                                                                      data reduction
                                                                                      requirements.
Sec.   63.9(a)-(e), (g)-(j).........  Notification             Yes.................
                                       Requirements.
Sec.   63.9(f)......................  Notification of VE/      No..................  Subpart IIIII does not have
                                       Opacity Test.                                  opacity and visible
                                                                                      emission standards.
Sec.   63.9(k)......................  Electronic reporting     Yes.................  Only as specified in Sec.
                                       procedures.                                    63.9(j).
Sec.   63.10(a); (b)(1); (b)(2)(vi)-  Recordkeeping/Reporting  Yes.................
 (xii), (xiv); (b)(3); (c)(1)-(14);
 (d)(1), (4); (e); (f).
Sec.   63.10(b)(2)(i)-(v)...........  Recordkeeping/Reporting  Yes.................  Only applies until the date
                                       Associated with                                specified in Sec.
                                       Startup, Shutdown, and                         63.8186(a)(3).
                                       Malfunctions.
Sec.   63.10(b)(2)(xiii)............  CMS Records for RATA     No..................  Subpart IIIII does not
                                       Alternative.                                   require CEMS.
Sec.   63.10(c)(15).................  Use of SSM Plan........  Yes.................  Only applies until the date
                                                                                      specified in Sec.
                                                                                      63.8186(a)(3).
Sec.   63.10(d)(2)..................  Performance Test         No..................  This subpart at 63.8232(g)
                                       Results.                                       specifies how and when the
                                                                                      performance test results
                                                                                      are reported
                                                                                      electronically.
Sec.   63.10(d)(3)..................  Reporting Opacity or VE  No..................  Subpart IIIII does not have
                                       Observations.                                  opacity and visible
                                                                                      emission standards.
Sec.   63.10(d)(5)..................  Startup, Shutdown, and   No..................
                                       Malfunction Reports.
Sec.   63.10(e)(2)(i)...............  CEM Reporting..........  Yes.................  Except this subpart
                                                                                      specifies how and when the
                                                                                      performance evaluation
                                                                                      results are reported.
Sec.   63.11........................  Flares.................  No..................  Subpart IIIII does not
                                                                                      require flares.
Sec.   63.12........................  Delegation.............  Yes.................
Sec.   63.13........................  Addresses..............  Yes.................
Sec.   63.14........................  Incorporation by         Yes.................
                                       Reference.
Sec.   63.15........................  Availability of          Yes.................
                                       Information.
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[FR Doc. 2022-09658 Filed 5-5-22; 8:45 am]
BILLING CODE 6560-50-P