[Federal Register Volume 87, Number 7 (Tuesday, January 11, 2022)]
[Proposed Rules]
[Pages 1616-1655]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-28273]



[[Page 1615]]

Vol. 87

Tuesday,

No. 7

January 11, 2022

Part V





Environmental Protection Agency





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40 CFR Part 63





National Emission Standards for Hazardous Air Pollutants: Primary 
Copper Smelting Residual Risk and Technology Review and Primary Copper 
Smelting Area Source Technology Review; Proposed Rule

  Federal Register / Vol. 87 , No. 7 / Tuesday, January 11, 2022 / 
Proposed Rules  

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2020-0430; FRL-7522-01-OAR]
RIN 2060-AU63


National Emission Standards for Hazardous Air Pollutants: Primary 
Copper Smelting Residual Risk and Technology Review and Primary Copper 
Smelting Area Source Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: This proposal presents the results of the U.S. Environmental 
Protection Agency's (EPA's) residual risk and technology review (RTR) 
for the National Emission Standards for Hazardous Air Pollutants 
(NESHAP) for major source Primary Copper Smelters as required under the 
Clean Air Act (CAA). Pursuant to the CAA, this action also presents the 
results of the technology review for the Primary Copper Smelting area 
source NESHAP. The EPA is proposing new emissions standards in the 
major source NESHAP. The EPA is also proposing to remove exemptions for 
periods of startup, shutdown, and malfunction (SSM) and specify that 
the emission standards apply at all times and require electronic 
reporting of performance test results and notification of compliance 
reports.

DATES: Comments. Comments must be received on or before February 25, 
2022. Under the Paperwork Reduction Act (PRA), comments on the 
information collection provisions are best assured of consideration if 
the Office of Management and Budget (OMB) receives a copy of your 
comments on or before February 10, 2022.
    Public hearing. If anyone contacts us requesting a public hearing 
on or before January 18, 2022, the EPA will hold a virtual public 
hearing. See SUPPLEMENTARY INFORMATION for information on requesting 
and registering for a public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2020-0430, by any of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov/ 
(our preferred method). Follow the online instructions for submitting 
comments.
     Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-2020-0430 in the subject line of the message.
     Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-
2020-0430.
     Mail: U.S. Environmental Protection Agency, EPA Docket 
Center, Docket ID No. EPA-HQ-OAR-2020-0430, Mail Code 28221T, 1200 
Pennsylvania Avenue NW, Washington, DC 20460.
     Hand/Courier Delivery: EPA Docket Center, WJC West 
Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 20004. 
The Docket Center's hours of operation are 8:30 a.m.-4:30 p.m., Monday-
Friday (except federal holidays).
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov/, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the SUPPLEMENTARY 
INFORMATION section of this document. Out of an abundance of caution 
for members of the public and our staff, the EPA Docket Center and 
Reading Room are closed to the public, with limited exceptions, to 
reduce the risk of transmitting COVID-19. Our Docket Center staff will 
continue to provide remote customer service via email, phone, and 
webform. The EPA encourages the public to submit comments via https://www.regulations.gov/ or email, as there may be a delay in processing 
mail and faxes. Hand deliveries and couriers may be received by 
scheduled appointment only. For further information 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 proposed 
action, contact Tonisha Dawson, 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) 541-1454; 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 (C539-02), 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) 541-4991; and email address: [email protected].

SUPPLEMENTARY INFORMATION:
    Executive Summary. This proposal presents the results of the EPA's 
residual risk and technology review (RTR) for the NESHAP for major 
source Primary Copper Smelters as required under the CAA. Pursuant to 
the CAA, this action also presents the results of the technology review 
for the Primary Copper Smelting area source NESHAP.
    Based on the results of the risk review, the EPA is proposing that 
risks from emissions of air toxics from this major source category are 
unacceptable. The EPA also completed a demographic analysis which 
indicates that elevated cancer risks associated with emissions from the 
major source category disproportionately affect communities with 
environmental justice concerns, including low-income residents, Native 
Americans, and Hispanics living near these facilities. To address these 
risks, the EPA is proposing new emissions standards in the major source 
NESHAP, which will reduce risks to an acceptable level, and is also 
proposing work practice standards to provide an ample margin of safety 
to protect public health.
    The EPA is also proposing new emissions standards for the major 
source NESHAP to address currently unregulated emissions of hazardous 
air pollutants (HAP), as follows: Particulate matter (PM), as a 
surrogate for particulate HAP metals, for anode refining furnace point 
source emissions; and PM for roofline emissions from anode refining 
furnaces, smelting furnaces, and converters. EPA is also proposing new 
emission standards for mercury emissions from any combination of stacks 
from dryers, converters, anode refining furnaces, and smelting 
furnaces. The EPA is proposing test methods for roofline PM emissions 
and amending the test methods to incorporate by reference three 
voluntary consensus standards (VCS).
    Under the technology review, the EPA identified no developments in 
practices, processes, or control technologies to achieve further 
emissions reductions beyond the controls and reductions proposed under 
the risk review for major sources. With regard to primary copper 
smelting area sources, the Agency did not identify any developments in 
practices, processes, or control technologies.
    The EPA is also proposing to remove exemptions for periods of 
startup, shutdown, and malfunction (SSM) and specify that the emission 
standards apply at all times and require electronic reporting of 
performance test results and notification of compliance reports. 
Implementation of these proposed rules is expected to reduce HAP metal 
emissions from primary copper

[[Page 1617]]

smelters, improve human health, and reduce environmental impacts 
associated with those emissions.
    Participation in virtual public hearing. Please note that the EPA 
is deviating from its typical approach for public hearings because the 
President has declared a national emergency. Due to the current Centers 
for Disease Control and Prevention (CDC) recommendations, as well as 
state and local orders for social distancing to limit the spread of 
COVID-19, the EPA cannot hold in-person public meetings at this time.
    To request a virtual public hearing, contact the public hearing 
team at (888) 372-8699 or by email at [email protected]. If 
requested, the virtual hearing will be held on January 26, 2022. The 
hearing will convene at 9:00 a.m. Eastern Time (ET) and will conclude 
at 3:00 p.m. ET. The EPA may close a session 15 minutes after the last 
pre-registered speaker has testified if there are no additional 
speakers. The EPA will announce further details at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air.
    The EPA will begin pre-registering speakers for the hearing upon 
publication of this document in the Federal Register. To register to 
speak at the virtual hearing, please use the online registration form 
available at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air or 
contact the public hearing team at (888) 372-8699 or by email at 
[email protected]. The last day to pre-register to speak at the 
hearing will be January 24, 2022. Prior to the hearing, the EPA will 
post a general agenda that will list pre-registered speakers in 
approximate order at: https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air.
    The EPA will make every effort to follow the schedule as closely as 
possible on the day of the hearing; however, please plan for the 
hearings to run either ahead of schedule or behind schedule.
    Each commenter will have 5 minutes to provide oral testimony. The 
EPA encourages commenters to provide the EPA with a copy of their oral 
testimony electronically (via email) by emailing it to 
[email protected]. The EPA also recommends submitting the text of 
your oral testimony as written comments to the rulemaking docket.
    The EPA may ask clarifying questions during the oral presentations 
but will not respond to the presentations at that time. Written 
statements and supporting information submitted during the comment 
period will be considered with the same weight as oral testimony and 
supporting information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will 
be posted online at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air. While the EPA expects the hearing to go forward as set 
forth above, please monitor our website or contact the public hearing 
team at (888) 372-8699 or by email at [email protected] to 
determine if there are any updates. The EPA does not intend to publish 
a document in the Federal Register announcing updates.
    If you require the services of a translator or a special 
accommodation such as audio description, please pre-register for the 
hearing with the public hearing team and describe your needs by January 
18, 2022. The EPA may not be able to arrange accommodations without 
advanced notice.
    Docket. The EPA has established a docket for this rulemaking under 
Docket ID No. EPA-HQ-OAR-2020-0430. All documents in the docket are 
listed in https://www.regulations.gov/. Although listed, some 
information is not publicly available, e.g., Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the internet and will be publicly available only in hard 
copy. With the exception of such material, publicly available docket 
materials are available electronically in Regulations.gov.
    Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2020-0430. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at https://www.regulations.gov/, including any personal 
information provided, unless the comment includes information claimed 
to be CBI or other information whose disclosure is restricted by 
statute. Do not submit electronically any information that you consider 
to be CBI or other information whose disclosure is restricted by 
statute. This type of information should be submitted by mail as 
discussed below.
    The EPA may publish any comment received to its public docket. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the Web, cloud, or other 
file sharing system). For additional submission methods, the full EPA 
public comment policy, information about CBI or multimedia submissions, 
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    The https://www.regulations.gov/ website allows you to submit your 
comment anonymously, which means the EPA will not know your identity or 
contact information unless you provide it in the body of your comment. 
If you send an email comment directly to the EPA without going through 
https://www.regulations.gov/, your email address will be automatically 
captured and included as part of the comment that is placed in the 
public docket and made available on the internet. If you submit an 
electronic comment, the EPA recommends that you include your name and 
other contact information in the body of your comment and with any 
digital storage media you submit. If the EPA cannot read your comment 
due to technical difficulties and cannot contact you for clarification, 
the EPA may not be able to consider your comment. Electronic files 
should not include special characters or any form of encryption and be 
free of any defects or viruses. For additional information about the 
EPA's public docket, visit the EPA Docket Center homepage at https://www.epa.gov/dockets.
    The EPA is temporarily suspending its Docket Center and Reading 
Room for public visitors, with limited exceptions, to reduce the risk 
of transmitting COVID-19. Our Docket Center staff will continue to 
provide remote customer service via email, phone, and webform. The EPA 
encourages the public to submit comments via https://www.regulations.gov/ as there may be a delay in processing mail and 
faxes. Hand deliveries or couriers will be received by scheduled 
appointment only. For further information and updates on EPA Docket 
Center services, please visit us online at https://www.epa.gov/dockets.
    The EPA continues to carefully and continuously monitor information 
from the CDC, local area health departments, and our Federal partners 
so that the Agency can respond rapidly as conditions change regarding 
COVID-19.
    Submitting CBI. Do not submit information containing CBI to the EPA 
through https://www.regulations.gov/ or email. Clearly mark all of the

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information that you claim to be CBI. For CBI information on any 
digital storage media that you mail to the EPA, mark the outside of the 
digital storage media as CBI and then identify electronically within 
the digital storage media the specific information that is claimed as 
CBI. In addition to one complete version of the comments that includes 
information claimed as CBI, you must submit a copy of the comments that 
does not contain the information claimed as CBI directly to the public 
docket through the procedures outlined in Instructions above. If you 
submit any digital storage media that does not contain CBI, mark the 
outside of the digital storage media clearly that it does not contain 
CBI. Information not marked as CBI will be included in the public 
docket and the EPA's electronic public docket without prior notice. 
Information marked as CBI will not be disclosed except in accordance 
with procedures set forth in 40 Code of Federal Regulations (CFR) part 
2. Send or deliver information identified as CBI only to the following 
address: Office of Air Quality Planning and Standards Document Control 
Officer (C404-02), OAQPS, U.S. Environmental Protection Agency, 
Research Triangle Park, North Carolina 27711, Attention Docket ID No. 
EPA-HQ-OAR-2020-0430. Note that written comments containing CBI and 
submitted by mail may be delayed and no hand deliveries will be 
accepted.
    Preamble acronyms and abbreviations. The Agency uses multiple 
acronyms and terms in this preamble. 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:

ACI activated carbon injection
AEGL acute exposure guideline level
AERMOD air dispersion model used by the HEM-4 model
BTF beyond-the-floor
CAA Clean Air Act
CalEPA California EPA
CBI Confidential Business Information
CFR Code of Federal Regulations
mg/dscm milligrams per dry standard cubic meter
ECHO Enforcement and Compliance History Online
EPA Environmental Protection Agency
ERPG emergency response planning guideline
ERT Electronic Reporting Tool
GACT generally available control technology
HAP hazardous air pollutant(s)
HCl hydrochloric acid
HEM-4 Human Exposure Model, Version 1.5.5
HF hydrogen fluoride
HI hazard index
HQ hazard quotient
ICR Information Collection Request
IRIS Integrated Risk Information System
km kilometer
MACT maximum achievable control technology
mg/kg-day milligrams per kilogram per day
mg/m\3\ milligrams per cubic meter
MIR maximum individual risk
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System
NEI National Emissions Inventory
NESHAP national emission standards for hazardous air pollutants
NTTAA National Technology Transfer and Advancement Act
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PB-HAP hazardous air pollutants known to be persistent and bio-
accumulative in the environment
PM particulate matter
POM polycyclic organic matter
ppm parts per million
RBLC Reasonably Available Control Technology, Best Available Control 
Technology, and Lowest Achievable Emission Rate Clearinghouse
RfC reference concentration
RTR residual risk and technology review
SAB Science Advisory Board
SV screening value
SSM startup, shutdown, and malfunction
TOSHI target organ-specific hazard index
tpy tons per year
TRIM.FaTE Total Risk Integrated Methodology.Fate, Transport, and 
Ecological Exposure model
UF uncertainty factor
[micro]g/m\3\ microgram per cubic meter
URE unit risk estimate
USGS U.S. Geological Survey
VCS voluntary consensus standards

    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?
II. Background
    A. What is the statutory authority for this action?
    B. What is this source category and how does the current NESHAP 
regulate its HAP emissions?
    C. What data collection activities were conducted to support 
this action?
    D. What other relevant background information and data are 
available?
III. Analytical Procedures and Decision-Making
    A. How do we consider risk in our decision-making?
    B. How do we perform the technology review?
    C. How do we estimate post-MACT risk posed by the source 
category?
IV. Analytical Results and Proposed Decisions
    A. What actions are we taking pursuant to CAA sections 112(d)(2) 
and 112(d)(3)?
    B. What are the results of the risk assessment and analyses?
    C. What are our proposed decisions regarding risk acceptability, 
ample margin of safety, and adverse environmental effect?
    D. What are the results and proposed decisions based on our 
technology review?
    E. What other actions are we proposing?
    F. What compliance dates are we proposing?
V. Summary of Cost, Environmental, and Economic Impacts
    A. What are the affected sources?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
VI. Request for Comments
VII. Submitting Data Corrections
VIII. Incorporation by Reference
IX. Statutory and Executive Order Reviews
    A. Executive Order 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 and 1 CFR part 51
    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

I. General Information

A. Does this action apply to me?

    The source categories that are the subject of this proposal are 
Primary Copper Smelting Major Sources regulated under 40 CFR part 63, 
subpart QQQ, and Primary Copper Smelting Area Sources, regulated under 
40 CFR part 63, subpart EEEEEE. The North American Industry 
Classification System (NAICS) code for the primary copper smelting 
industry is 331410. This list of categories and NAICS codes is not 
intended to be exhaustive, but rather provides a guide for readers 
regarding the entities that this proposed action is likely to affect. 
The proposed standards, once promulgated, will be directly applicable 
to the affected sources. State, local, and tribal governments would not 
be directly affected by this proposed action. As defined in the Initial 
List of Categories of Sources Under Section 112(c)(1) of

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the Clean Air Act Amendments of 1990 (see 57 FR 31576, July 16, 1992) 
and Documentation for Developing the Initial Source Category List, 
Final Report (see EPA-450/3-91-030, July 1992), the Primary Copper 
Smelting major source category was defined as any major source facility 
engaged in the pyrometallurgical process used for the extraction of 
copper from sulfur oxides, native ore concentrates, or other copper 
bearing minerals. As originally defined, the category includes, but is 
not limited to, the following smelting process units: Roasters, 
smelting furnaces, and converters. Affected sources under the current 
major source NESHAP are concentrate dryers, smelting furnaces, slag 
cleaning vessels, converters, and fugitive emission sources. The area 
source category was added to the source category list in 2002 (67 FR 
70427, 70428). Affected sources under the area source NESHAP are 
concentrate dryers, smelting vessels (e.g., furnaces), converting 
vessels, matte drying and grinding plants, secondary gas systems, and 
anode refining operations.

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 action is available on the internet. Following signature by the 
EPA Administrator, the EPA will post a copy of this proposed action at 
https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air and at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-area-sources-national-emissions-standards. Following publication in the 
Federal Register, the EPA will post the Federal Register version of the 
proposal and key technical documents at these same websites. 
Information on the overall RTR program is available at https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous.
    The proposed changes to the CFR that would be necessary to 
incorporate the changes proposed in this action are presented in 
attachments to the two memoranda titled: Proposed Regulation Edits for 
40 CFR part 63, subpart QQQ: Primary Copper Smelting NESHAP Risk and 
Technology Review Proposal; and Proposed Regulatory Edits for 40 CFR 
part 63 Subpart EEEEEE: Primary Copper Smelting Area Sources NESHAP 
Technology Review Proposal, both of which are available in the docket 
for this action (Docket ID No. EPA-HQ-OAR-2020-0430). These documents 
include redline versions of the two regulations. Following signature by 
the EPA Administrator, the EPA will also post a copy of these two 
memoranda and the attachments to https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air and to https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-area-sources-national-emissions-standards.

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by sections 112 
and 301 of the CAA, as amended (42 U.S.C. 7401 et seq.). Section 112 of 
the CAA establishes a two-stage regulatory process to develop standards 
for emissions of HAP from stationary sources. Generally, the first 
stage involves establishing technology-based standards and the second 
stage involves evaluating those standards that are based on maximum 
achievable control technology (MACT) to determine whether additional 
standards are needed to address any remaining risk associated with HAP 
emissions. This second stage is required under CAA section 112(f) and 
is commonly referred to as the ``residual risk review.'' In addition to 
the residual risk review, section 112(d)(6) of the CAA requires the EPA 
to review standards set under CAA section 112 every 8 years and revise 
the standards as necessary taking into account any ``developments in 
practices, processes, or control technologies.'' This review is 
commonly referred to as the ``technology review.'' When the two reviews 
are combined into a single rulemaking, it is commonly referred to as 
the ``risk and technology review.'' The discussion that follows 
identifies the most relevant statutory sections and briefly explains 
the contours of the methodology used to implement these statutory 
requirements. A more comprehensive discussion appears in the document 
titled CAA Section 112 Risk and Technology Reviews: Statutory Authority 
and Methodology, in the docket for this rulemaking.
    In the first stage of the CAA section 112 standard setting process, 
the EPA promulgates technology-based standards under CAA section 112(d) 
for categories of sources identified as emitting one or more of the HAP 
listed in CAA section 112(b). Sources of HAP emissions are either major 
sources or area sources, and CAA section 112 establishes different 
requirements for major source standards and area source standards. 
``Major sources'' are those that emit or have the potential to emit 10 
tons per year (tpy) or more of a single HAP or 25 tpy or more of any 
combination of HAP. All other sources are ``area sources.'' For major 
sources, CAA section 112(d)(2) provides that the technology-based 
NESHAP must reflect the maximum degree of emission reductions of HAP 
achievable (after considering cost, energy requirements, and non-air 
quality health and environmental impacts). These standards are commonly 
referred to as MACT standards. CAA section 112(d)(3) also establishes a 
minimum control level for MACT standards, known as the MACT ``floor.'' 
In certain instances, as provided in CAA section 112(h), the EPA may 
set work practice standards in lieu of numerical emission standards. 
The EPA must also consider control options that are more stringent than 
the floor. Standards more stringent than the floor are commonly 
referred to as beyond-the-floor (BTF) standards. For area sources, CAA 
section 112(d)(5) gives the EPA discretion to set standards based on 
generally available control technologies or management practices (GACT 
standards) in lieu of MACT standards.
    The second stage in standard-setting focuses on identifying and 
addressing any remaining (i.e., ``residual'') risk pursuant to CAA 
section 112(f). For source categories subject to MACT standards, 
section 112(f)(2) of the CAA requires the EPA to determine whether 
promulgation of additional standards is needed to provide an ample 
margin of safety to protect public health or to prevent an adverse 
environmental effect. Section 112(d)(5) of the CAA provides that this 
residual risk review is not required for categories of area sources 
subject to GACT standards. Section 112(f)(2)(B) of the CAA further 
expressly preserves the EPA's use of the two-step approach for 
developing standards to address any residual risk and the Agency's 
interpretation of ``ample margin of safety'' developed in the National 
Emissions Standards for Hazardous Air Pollutants: Benzene Emissions 
from Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene 
Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery 
Plants (Benzene NESHAP) (54 FR 38044, September 14, 1989). The EPA 
notified Congress in the Residual Risk Report that the Agency intended 
to use the Benzene NESHAP approach in making CAA section 112(f) 
residual risk

[[Page 1620]]

determinations (EPA-453/R-99-001, p. ES-11). The EPA subsequently 
adopted this approach in its residual risk determinations and the 
United States Court of Appeals for the District of Columbia Circuit 
upheld the EPA's interpretation that CAA section 112(f)(2) incorporates 
the approach established in the Benzene NESHAP. See NRDC v. EPA, 529 
F.3d 1077, 1083 (D.C. Cir. 2008).
    The approach incorporated into the CAA and used by the EPA to 
evaluate residual risk and to develop standards under CAA section 
112(f)(2) is a two-step approach. In the first step, the EPA determines 
whether risks are acceptable. This determination ``considers all health 
information, including risk estimation uncertainty, and includes a 
presumptive limit on maximum individual lifetime [cancer] risk (MIR) 
\1\ of approximately 1 in 10 thousand.'' (54 FR at 38045). If risks are 
unacceptable, the EPA must determine the emissions standards necessary 
to reduce risk to an acceptable level without considering costs. In the 
second step of the approach, the EPA considers whether the emissions 
standards provide an ample margin of safety to protect public health 
``in consideration of all health information, including the number of 
persons at risk levels higher than approximately 1 in 1 million, as 
well as other relevant factors, including costs and economic impacts, 
technological feasibility, and other factors relevant to each 
particular decision.'' Id. The EPA must promulgate emission standards 
necessary to provide an ample margin of safety to protect public health 
or determine that the standards being reviewed provide an ample margin 
of safety without any revisions. After conducting the ample margin of 
safety analysis, the Agency considers whether a more stringent standard 
is necessary to prevent, taking into consideration costs, energy, 
safety, and other relevant factors, an adverse environmental effect.
---------------------------------------------------------------------------

    \1\ Although defined as ``maximum individual risk,'' MIR refers 
only to cancer risk. MIR, one metric for assessing cancer risk, is 
the estimated risk if an individual were exposed to the maximum 
level of a pollutant for a lifetime.
---------------------------------------------------------------------------

    CAA section 112(d)(6) separately requires the EPA to review 
standards promulgated under CAA section 112 and revise them ``as 
necessary (taking into account developments in practices, processes, 
and control technologies)'' no less often than every 8 years. While 
conducting the technology review, the EPA is not required to 
recalculate the MACT floor. Natural Resources Defense Council (NRDC) v. 
EPA, 529 F.3d 1077, 1084 (D.C. Cir. 2008). 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. Louisiana Environmental Action Network (LEAN) 
v. EPA, 955 F.3d 1088 (D.C. Cir. 2020).

B. What is this source category and how does the current NESHAP 
regulate its HAP emissions?

    The primary copper smelting source category includes any facility 
that uses a pyrometallurgical process to produce anode copper from 
copper ore concentrates. Primary copper smelting begins with copper 
mines supplying the ore concentrate (typically 30 percent copper). In 
most cases, the moisture is reduced from the ore concentrate in dryers, 
and then fed through a smelting furnace where it is melted and reacts 
to produce copper matte. One existing smelter is able to feed its 
copper concentrate directly to the smelting furnace without prior 
drying. Copper matte is a molten solution of copper sulfide mixed with 
iron sulfide and is about 60 percent copper. The solution is further 
refined using converters to make blister copper, which is approximately 
98 percent copper. Converters use oxidation to remove sulfide as sulfur 
dioxide (SO2) gas and the iron as a ferrous oxide slag. The 
majority of the SO2 gases are sent to a sulfuric acid plant. 
The slag is removed, cooled, and often processed again to remove any 
residual copper. The blister copper is reduced in the anode furnace to 
remove impurities and oxygen, typically by injecting natural gas and 
steam, to produce a high purity copper. The molten copper from the 
anode refining furnace is poured into molds and cooled to produce solid 
copper ingots called anodes. This process is known as casting. The 
anodes are sent to a copper refinery, either on-site or at an off-site 
location, for further purification using an electrolytic process to 
obtain high purity copper that is sold as a product.
    The processing units of interest at primary copper smelters, 
because of their potential to generate HAP emissions, are the 
following: Dryers, smelting furnaces, copper converters, anode refining 
furnaces, and, if present, copper holding vessels, slag cleaning 
vessels, and matte drying and grinding plants. In addition, fugitive 
emissions are sources of HAP at primary copper smelters. The transfer 
of matte, converter slag, and blister copper is the primary source of 
fugitive emissions.
    There are three primary copper smelting facilities in the U.S. that 
are subject to the NESHAPs in this review. Two of the facilities 
(Asarco and Freeport--both located in Arizona) are major sources of HAP 
emissions and are subject to subpart QQQ, the major source NESHAP; the 
third facility (Kennecott--located in Utah) is an area source and 
subject to subpart EEEEEE, the area source NESHAP.
    Two of the facilities (Asarco and Kennecott) use flash smelting 
furnaces (the INCO smelting furnace and the Outotec[supreg], 
respectively). Flash smelting furnaces consist of blowing fine, dried 
copper sulfide concentrate and silica flux with air, oxygen-enriched 
air or oxygen into a hot hearth-type furnace. The sulfide minerals in 
the concentrate react with oxygen resulting in oxidation of the iron 
and sulfur, which produces heat and therefore melting of the solids. 
The molten matte and slag are removed separately from the furnace as 
they accumulate, and at the facility using the INCO furnace, the matte 
is transferred via ladles to the copper converters. The Freeport 
facility uses an ISA smelting furnace. The ISA smelt[supreg] process 
involves dropping wet feed through a feed port, such that dryers are 
not needed. A mixture of air, oxygen, and natural gas is blown through 
a vertical lance in the center of the furnace, generating heat and 
melting the feed. The molten metal is then tapped from the bottom and 
sent to an electric furnace to separate the matte from slag. The slag 
is removed from the electric furnace through tapholes and is 
transferred to slag pots via ladles. The matte is also removed from the 
electric furnace through tapholes and transferred to the converter via 
ladles.
    At the area source primary copper smelter, molten copper matte 
tapped from the Outotec[supreg] smelting furnace is not transferred as 
molten material directly to the converting vessel as is performed at 
the two major source smelters. Instead, the matte is first quenched 
with water to form solid granules of copper matte. These matte granules 
are then ground to a finer texture and fed to the flash converting 
furnace for the continuous converting of copper. The continuous copper 
converter differs significantly in design and operation from the 
cylindrical batch converters operated at the other U.S. smelters. 
Because there are no transfers of molten material between the smelting 
furnace and the continuous copper converter, this technology has 
inherently lower potential HAP emissions than a smelter using batch 
copper converting technology.

[[Page 1621]]

    Molten blister copper is transferred from the converting vessel to 
an anode furnace for refining to further remove residual impurities and 
oxygen. The blister copper is reduced in the anode refining furnace to 
remove oxygen, typically by injecting natural gas and steam to produce 
a high purity copper. The molten copper from the anode refining furnace 
is poured into molds to produce solid copper ingots called anodes. The 
anode copper is sent to a copper refinery, either on-site or at another 
location, where it is further purified using an electrolytic process to 
obtain the high purity copper that is sold as a product. The copper 
refinery is not part of the primary copper smelting source category.
    The current NESHAP for major sources (40 CFR part 63, subpart QQQ) 
was proposed on April 20, 1998 (63 FR 19582), with a supplement to the 
proposed rule published on June 26, 2000 (65 FR 39326). The final rule, 
promulgated on June 12, 2002 (67 FR 40478), established PM standards as 
a surrogate for HAP metals for copper concentrate dryers, smelting 
furnaces, slag cleaning vessels, and existing converters. The major 
source NESHAP applies to major sources that use batch copper 
converters. Regarding new sources, the NESHAP prohibits batch 
converters for new sources, which indirectly means that any new source 
would need to have continuous converters, similar to the area source 
(Kennecott), or another technology. The converter building is subject 
to an opacity limit that only applies during performance testing. A 
fugitive dust plan is required to minimize fugitive dust emissions. 
Subpart QQQ also establishes requirements to demonstrate initial and 
continuous compliance with all applicable emission limitations, work 
practice standards, and operation and maintenance requirements. Annual 
performance testing is required to demonstrate compliance.
    The NESHAP for area sources (40 CFR part 63, subpart EEEEEE) 
establishes GACT standards for primary copper smelting area sources and 
was proposed on October 6, 2006 (71 FR 59302), and finalized on January 
23, 2007 (72 FR 2930). Technical corrections were then published on 
July 3, 2007, via direct final rule (72 FR 36363). The affected sources 
(i.e., copper concentrate dryers, smelting vessels, converting vessels, 
matte drying and grinding plants, secondary gas systems and anode 
refining departments) are subject to PM limits as a surrogate for HAP 
metals. Compliance must be demonstrated by performance tests conducted 
every 2.5 years.

C. What data collection activities were conducted to support this 
action?

    For the Primary Copper Smelting source category, the EPA used the 
best available data. Initially, emissions and supporting data from the 
2017 National Emissions Inventory (NEI) were gathered to develop the 
initial draft model input file for the residual risk assessments for 
major source primary copper smelters. The NEI is a database that 
contains information about sources that emit criteria air pollutants, 
their precursors, and HAP. The database includes estimates of annual 
air pollutant emission from point, nonpoint, and mobile sources in the 
50 states, the District of Columbia, Puerto Rico, and the U.S. Virgin 
Islands. The EPA collects this information and releases an updated 
version of the NEI database every 3 years. The NEI includes data 
necessary for conducting risk modeling, including annual HAP emissions 
estimates from individual emission sources at facilities and the 
related emissions release parameters.
    The Arizona Department of Environmental Quality (ADEQ) provided 
2018 emissions test data for both major source primary copper smelters 
located in that state, which allowed the EPA to use more current metal 
HAP emissions data than what was available in the 2017 NEI in some 
cases. The data from ADEQ and the NEI were used to develop an initial 
draft risk model input file. This initial draft model file was posted 
to the EPA's Primary Copper website on February 26, 2020, and 
stakeholders were provided an opportunity to voluntarily review and 
provide input regarding the sources of emissions and release parameters 
that were reported in the NEI. The Asarco and Freeport facilities 
provided input, and the modeling file was finalized. The data include 
multiple emissions test reports for PM and HAP metals for point source 
emissions from both facilities and seven test reports for emissions 
tests conducted in 2018, 2019 and 2020 for process fugitive emissions 
for anode refining, smelting furnaces and converters at Freeport. 
However, we have no test data for Asarco process fugitive emissions. 
The process fugitive emissions estimates for Asarco are based on 
emissions factors and process information. Therefore, we have higher 
confidence and less uncertainty with our emissions estimates for 
Freeport as compared to Asarco. We made an adjustment to the lead 
emissions estimates from the anode refining roofline at Freeport by 
applying a weighting factor to one of the 2018 test results. This 
factor is based on information in the document titled: Technical Report 
on Test Method for Roofline Lead Emissions, Operational Influences 
During Testing, And Effect of Smelter Reconfiguration, by Trinity 
Consultants, December 2018, which is available in the docket for this 
action. The data and data sources used to support this action and 
additional information on the development of the modeling file are 
described in Appendix 1 to the Residual Risk Assessment for the Primary 
Copper Smelting Major Source Category in Support of the 2021 Risk and 
Technology Review Proposed Rule, which is available in the docket for 
this proposed rule (Docket ID No. EPA-HQ-OAR-2020-0430). Additional 
information is provided in section II.D below.

D. What other relevant background information and data are available?

    The EPA used multiple sources of information to support this 
proposed action. Before developing the final list of affected 
facilities described in section II.B of this preamble, the EPA's 
Enforcement and Compliance History Online (ECHO) database was used as a 
tool to identify potentially affected facilities with primary copper 
smelting operations that are subject to the NESHAPs. The ECHO database 
provides integrated compliance and enforcement information for 
approximately 800,000 regulated facilities nationwide. The EPA also 
reviewed the compliance history on the ADEQ website, active consent 
decrees, and consent orders to verify that the facilities were 
accurately classified as major sources.
    During the technology review, the EPA examined information in the 
Reasonably Available Control Technology (RACT)/Best Available Control 
Technology (BACT)/Lowest Achievable Emission Rate (LAER) Clearinghouse 
(RBLC) to identify technologies in use and determine whether there have 
been relevant developments in practices, processes, or control 
technologies. The RBLC is a database that contains case specific 
information on air pollution technologies that have been required to 
reduce the emissions of air pollutants from stationary sources. Under 
the EPA's New Source Review (NSR) program, if a facility is planning 
new construction or a modification that will significantly increase air 
emissions, an NSR permit must be obtained. This central database 
promotes the sharing of information among permitting agencies and aids 
in case-by-case determinations for NSR permits. The EPA also reviewed 
subsequent air toxics regulatory actions for other source categories 
and

[[Page 1622]]

information from a virtual site visit at the Freeport plant to 
determine whether there have been developments in practices, processes, 
or control technologies in the Primary Copper Smelting source category. 
The docket for this rulemaking contains the following document which 
provides more information on the technology review: Final Technology 
Review for the Primary Copper Smelting Source Category.

III. Analytical Procedures and Decision-Making

    In this section, the Agency describes the analyses performed to 
support the proposed decisions for the RTR and other issues addressed 
in this proposal. In this proposed action, pursuant to CAA section 
112(f), the EPA conducted a risk review for the major sources in the 
primary copper smelting source category. Consistent with CAA section 
112(f)(5), the risk review did not cover the area source category. 
Therefore, the discussions of risk assessment procedures described in 
the following paragraphs apply only to the major source category. 
However, pursuant to CAA section 112(d)(6), the EPA conducted a 
technology review for the NESHAPs covering both the major source 
category and the area source category (40 CFR part 63, subpart EEEEEE). 
Therefore, the following discussions of the technology reviews apply to 
both major sources and area sources.

A. How do we consider risk in our decision-making?

    As discussed in section II.A of this preamble and in the Benzene 
NESHAP, in evaluating and developing standards under CAA section 
112(f)(2), the Agency applies a two-step approach to determine whether 
or not risks are acceptable and to determine if the standards provide 
an ample margin of safety to protect public health. As explained in the 
Benzene NESHAP, ``the first step judgment on acceptability cannot be 
reduced to any single factor'' and, thus, ``[t]he Administrator 
believes that the acceptability of risk under section 112 is best 
judged on the basis of a broad set of health risk measures and 
information.'' (54 FR at 38046). Similarly, with regard to the ample 
margin of safety determination, ``the Agency again considers all of the 
health risk and other health information considered in the first step. 
Beyond that information, additional factors relating to the appropriate 
level of control will also be considered, including cost and economic 
impacts of controls, technological feasibility, uncertainties, and any 
other relevant factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors 
the EPA may consider in making determinations and how the EPA may weigh 
those factors for each source category. The EPA conducts a risk 
assessment that provides estimates of the MIR posed by emissions of HAP 
that are carcinogens from each source in the source category, the 
hazard index (HI) for chronic exposures to HAP with the potential to 
cause noncancer health effects, and the hazard quotient (HQ) for acute 
exposures to HAP with the potential to cause noncancer health 
effects.\2\ The assessment also provides estimates of the distribution 
of cancer risk within the exposed populations, cancer incidence, and an 
evaluation of the potential for an adverse environmental effect. The 
scope of the EPA's risk analysis is consistent with the explanation in 
EPA's response to comments on our policy under the Benzene NESHAP:
---------------------------------------------------------------------------

    \2\ The MIR is defined as the cancer risk associated with a 
lifetime of exposure at the highest concentration of HAP where 
people are likely to live. The HQ is the ratio of the potential HAP 
exposure concentration to the noncancer dose-response value; the HI 
is the sum of HQs for HAP that affect the same target organ or organ 
system.

    The policy chosen by the Administrator permits consideration of 
multiple measures of health risk. Not only can the MIR figure be 
considered, but also incidence, the presence of noncancer health 
effects, and the uncertainties of the risk estimates. In this way, 
the effect on the most exposed individuals can be reviewed as well 
as the impact on the general public. These factors can then be 
weighed in each individual case. This approach complies with the 
Vinyl Chloride mandate that the Administrator ascertain an 
acceptable level of risk to the public by employing his expertise to 
assess available data. It also complies with the Congressional 
intent behind the CAA, which did not exclude the use of any 
particular measure of public health risk from the EPA's 
consideration with respect to CAA section 112 regulations, and 
thereby implicitly permits consideration of any and all measures of 
health risk which the Administrator, in his judgment, believes are 
---------------------------------------------------------------------------
appropriate to determining what will ``protect the public health''.

(54 FR at 38057). Thus, the level of the MIR is only one factor to be 
weighed in determining acceptability of risk. The Benzene NESHAP 
explained that ``an MIR of approximately one in 10 thousand should 
ordinarily be the upper end of the range of acceptability. As risks 
increase above this benchmark, they become presumptively less 
acceptable under CAA section 112, and would be weighed with the other 
health risk measures and information in making an overall judgment on 
acceptability. Or, the Agency may find, in a particular case, that a 
risk that includes an MIR less than the presumptively acceptable level 
is unacceptable in the light of other health risk factors.'' Id. at 
38045. In other words, risks that include an MIR above 100-in-1 million 
may be determined to be acceptable, and risks with an MIR below that 
level may be determined to be unacceptable, depending on all of the 
available health information. Similarly, with regard to the ample 
margin of safety analysis, the EPA stated in the Benzene NESHAP that: 
``EPA believes the relative weight of the many factors that can be 
considered in selecting an ample margin of safety can only be 
determined for each specific source category. This occurs mainly 
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at 
38061. The Agency also considers the uncertainties associated with the 
various risk analyses, as discussed earlier in this preamble, in our 
determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information 
to date in making residual risk determinations. At this time, the 
Agency does not attempt to quantify the HAP risk that may be associated 
with emissions from other facilities that do not include the source 
category under review, mobile source emissions, natural source 
emissions, persistent environmental pollution, or atmospheric 
transformation in the vicinity of the sources in the category.
    The EPA understands the potential importance of considering an 
individual's total exposure to HAP in addition to considering exposure 
to HAP emissions from the source category and facility. The Agency 
recognizes that such consideration may be particularly important when 
assessing noncancer risk, where pollutant-specific exposure health 
reference levels (e.g., reference concentrations (RfCs)) are based on 
the assumption that thresholds exist for adverse health effects. For 
example, the EPA recognizes that, although exposures attributable to 
emissions from a source category or facility alone may not indicate the 
potential for increased risk of adverse noncancer health effects in a 
population, the exposures resulting from emissions from the facility in 
combination with emissions from all of the other sources (e.g., other 
facilities) to which an individual is exposed may be sufficient to 
result in an increased risk of adverse noncancer health effects. In May 
2010, the Science Advisory Board

[[Page 1623]]

(SAB) advised the EPA ``that RTR assessments will be most useful to 
decision makers and communities if results are presented in the broader 
context of aggregate and cumulative risks, including background 
concentrations and contributions from other sources in the area.'' \3\
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    \3\ Recommendations of the SAB Risk and Technology Review 
Methods Panel are provided in their report, which is available at: 
https://yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
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    In response to the SAB recommendations, the EPA incorporates 
cumulative risk analyses into its RTR risk assessments. The Agency (1) 
conducts facility-wide assessments, which include source category 
emission points, as well as other emission points within the 
facilities; (2) combines exposures from multiple sources in the same 
category that could affect the same individuals; and (3) for some 
persistent and bioaccumulative pollutants, analyzes the ingestion route 
of exposure. In addition, the RTR risk assessments consider aggregate 
cancer risk from all carcinogens and aggregated noncancer HQs for all 
noncarcinogens affecting the same target organ or target organ system.
    Although the EPA is interested in placing source category and 
facility-wide HAP risk in the context of total HAP risk from all 
sources combined in the vicinity of each source, the EPA is also 
concerned about the uncertainties of doing so. Estimates of total HAP 
risk from emission sources other than those that the Agency has studied 
in depth during this RTR review would have significantly greater 
associated uncertainties than the source category or facility-wide 
estimates. Such aggregate or cumulative assessments would compound 
those uncertainties, making the assessments too unreliable.

B. How do we perform the technology review?

    Our technology review primarily focuses on the identification and 
evaluation of developments in practices, processes, and control 
technologies that have occurred since the MACT standards were 
promulgated. Where we identify such developments, we analyze their 
technical feasibility, estimated costs, energy implications, and non-
air environmental impacts. The EPA also considers the emission 
reductions associated with applying each development. This analysis 
informs our decision of whether it is ``necessary'' to revise the 
emissions standards. In addition, the Agency considers the 
appropriateness of applying controls to new sources versus retrofitting 
existing sources. For this exercise, the EPA considers any of the 
following to be a ``development'':
     Any add-on control technology or other equipment that was 
not identified and considered during development of the original MACT 
standards;
     Any improvements in add-on control technology or other 
equipment (that were identified and considered during development of 
the original MACT standards) that could result in additional emissions 
reduction;
     Any work practice or operational procedure that was not 
identified or considered during development of the original MACT 
standards;
     Any process change or pollution prevention alternative 
that could be broadly applied to the industry and that was not 
identified or considered during development of the original MACT 
standards; and
     Any significant changes in the cost (including cost 
effectiveness) of applying controls (including controls the EPA 
considered during the development of the original MACT standards).
    In addition to reviewing the practices, processes, and control 
technologies that were considered at the time the EPA originally 
developed the NESHAP, we review a variety of data sources in our 
investigation of potential practices, processes, or controls to 
consider. The EPA also reviews the NESHAP and the available data to 
determine if there are any unregulated emissions of HAP within the 
source category, and evaluate the data for use in developing new 
emission standards. See sections II.C and II.D of this preamble for 
information on the specific data sources that were reviewed as part of 
the technology review.

C. How do we estimate post-MACT risk posed by the source category?

    In this section, the EPA provides a complete description of the 
types of analyses that we generally perform during the risk assessment 
process. In some cases, the Agency does not perform a specific analysis 
because it is not relevant. For example, in the absence of emissions of 
hazardous air pollutants known to be persistent and bioaccumulative in 
the environment (PB-HAP), the Agency would not perform a multipathway 
exposure assessment. If an analysis is not performed, the Agency will 
provide the reason. While we present all of our risk assessment 
methods, the Agency only presents risk assessment results for the 
analyses actually conducted (see section IV.B of this preamble).
    The EPA conducts a risk assessment that provides estimates of the 
MIR for cancer posed by the HAP emissions from each source in the 
source category, the HI for chronic exposures to HAP with the potential 
to cause noncancer health effects, and the HQ for acute exposures to 
HAP with the potential to cause noncancer health effects. The 
assessment also provides estimates of the distribution of cancer risk 
within the exposed populations, cancer incidence, and an evaluation of 
the potential for an adverse environmental effect. The eight sections 
that follow this paragraph describe how the Agency estimated emissions 
and conducted the risk assessment. The docket for this rulemaking 
contains the following document which provides more information on the 
risk assessment inputs and models: Residual Risk Assessment for the 
Primary Copper Smelting Major Source Category in Support of the 2021 
Risk and Technology Review Proposed Rule. The methods used to assess 
risk (as described in the eight primary steps below) are consistent 
with those described by the EPA in the document reviewed by a panel of 
the EPA's SAB in 2009 \4\ and described in the SAB review report issued 
in 2010. They are also consistent with the key recommendations 
contained in that report.
---------------------------------------------------------------------------

    \4\ U.S. EPA. Risk and Technology Review (RTR) Risk Assessment 
Methodologies: For Review by the EPA's Science Advisory Board with 
Case Studies--MACT I Petroleum Refining Sources and Portland Cement 
Manufacturing, June 2009. EPA-452/R-09-006. https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous.
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1. How did we estimate actual emissions and identify the emissions 
release characteristics?
    To create the initial modeling input file, the Agency gathered 
actual HAP emissions data from the 2017 NEI and 2018 emissions 
estimates provided by ADEQ. The 2019 emissions data for Asarco and 
Freeport were not available when the initial modeling input file was 
developed. The Asarco plant's smelting operation was shut down for a 
significant portion of 2018 due to equipment upgrades. Since the 2019 
emissions data for Asarco were not available, the 2017 NEI data were 
used for the initial modeling input file. The Freeport plant made 
significant upgrades in 2017, so the 2018 emissions data were used for 
the initial modeling input file as the best representation of the 
current plant configuration. The modeling input file was posted on the 
EPA website on February 26, 2020, for

[[Page 1624]]

public review. Asarco and Freeport provided comments, revisions to the 
initial modeling file, and supporting documents, which consisted of 
2019 emissions data and various performance test reports. The data 
provided by both facilities were used to develop the final modeling 
input file.
    For each NEI record, the EPA reviewed the standard classification 
code (SCC) and emission unit and process descriptions, and assigned the 
record to one of the emission process groups (i.e., Anode Furnaces; 
Anode Refining Roofline; Combustion; Converters; Anode Furnaces and 
Converters; Converters Roofline; Dryers, Furnaces, Converters and Acid 
Plant; Non-process Fugitives; Rod Plant; Smelting Furnace Roofline; 
Smelting Furnace Secondary; Smelting Furnaces and Converters).
    If the SCC and emission unit and process descriptions were 
ambiguous for a specific NEI record, the Agency used the facility air 
permits and flow diagrams to help us assign the appropriate emission 
process group. Both facilities have many combined gas streams that vent 
to a common control system and/or stack. In those cases, there may be 
multiple emissions sources included in the Emission Process Group 
Description. For example, at Asarco, the exhaust gases from the two 
dryers and flash furnace are vented to the same baghouse. The facility 
has a sampling port at the exhaust of the baghouse to measure emissions 
during performance testing. The emission sources associated with this 
example are represented by ``Dryers and Flash Furnace'' under the 
Emission Process Group Description.
    The EPA did not conduct a risk review pursuant to section 112(f) of 
the CAA for Kennecott since it is an area source subject to GACT 
standards (not MACT standards). However, we did obtain emissions 
estimates and evaluated some information on ambient monitoring data 
near the facility.
    Based on reported 2017 estimates to the NEI, Kennecott emits an 
estimated 5.6 tpy of lead and 1.6 tpy of arsenic. However, we do not 
have any HAP metals emissions test data for Kennecott. Therefore, we 
consider these estimates uncertain and we are soliciting comments, data 
and additional information regarding these emissions estimates.
    With regard to ambient monitoring data, Utah Division of Air 
Quality (DAQ) conducted lead monitoring at the Magna station near the 
Kennecott copper smelter from January 2010 through June 2017 (see 
Figure 18 of the memorandum titled Emissions Data Used for Primary 
Copper Smelting Risk and Technology Review (RTR) Modeling Files). At 
that time Utah DAQ was able to demonstrate that the likelihood of 
violating the National Ambient Air Quality Standard (NAAQS) for lead 
was so low, it would no longer be necessary to run the monitor. With 
EPA's concurrence, the Magna lead monitor was shut down in June 2017. 
Utah DAQ and the EPA continue to evaluate the development of 
requirements, such as source emission thresholds, population, and NAAQS 
revisions, that may trigger the necessity to resume monitoring lead in 
Utah.\5\ Nevertheless, the Agency solicits comments, data and 
additional information regarding these ambient monitoring data and how 
they should be considered in the context of the EPA's technology review 
of the Primary Copper Smelting area source NESHAP.
---------------------------------------------------------------------------

    \5\ Utah Division of Air Quality 2019 Annual Report. 2019. Utah 
Department of Environmental Quality--Air Quality. Available at: 
https://deq.utah.gov/air-quality/annual-reports-division-of-air-quality.
---------------------------------------------------------------------------

2. How did we estimate MACT-allowable emissions?
    The available emissions data in the RTR emissions dataset include 
estimates of the mass of HAP emitted during a specified annual time 
period. These ``actual'' emission levels are often lower than the 
emission levels allowed under the requirements of the current MACT 
standards. The emissions allowed under the MACT standards are referred 
to as the ``MACT-allowable'' emissions. The Agency discussed the 
consideration of both MACT-allowable and actual emissions in the final 
Coke Oven Batteries RTR (70 FR 19992, 19998-19999, April 15, 2005) and 
in the proposed and final Hazardous Organic NESHAP RTR (71 FR 34421, 
34428, June 14, 2006, and 71 FR 76603, 76609, December 21, 2006, 
respectively). In those actions, the Agency noted that assessing the 
risk at the MACT-allowable level is inherently reasonable since that 
risk reflects the maximum level facilities could emit and still comply 
with national emission standards. The EPA also explained that it is 
reasonable to consider actual emissions, where such data are available, 
in both steps of the risk analysis, in accordance with the Benzene 
NESHAP approach. (54 FR 38044.)
    The current Primary Copper Smelting NESHAP specifies numerical 
emission standards for each copper concentrate dryer, smelting vessel, 
and slag cleaning vessel. Consequently, the MACT-allowable emissions 
for each of these emission sources are assumed to be equal to the 
numerical emission standard. The NESHAP specifies work practice 
standards for fugitive dust sources. Therefore, the Agency believes 
that the actual fugitive dust sources emission levels are a reasonable 
estimation of the MACT-allowable emissions levels. The current NESHAP 
does not include standards for anode refining departments, anode 
refining rooflines, converter rooflines and smelting furnace rooflines. 
However, the EPA has determined that these sources are part of the 
source category and plans to propose MACT standards with this RTR. The 
MACT-allowable emissions for our baseline risk assessment for the anode 
refining departments, anode refining rooflines, converter rooflines and 
smelting furnace rooflines are assumed to be equal to the actual 
emissions, which are the estimated emissions prior to implementation of 
the proposed MACT standards.
    For further details on the assumptions and methodologies used to 
estimate MACT-allowable emissions, see Appendix X of the document 
titled Emissions Data Used for Primary Copper Smelting Risk and 
Technology Review (RTR) Modeling Files, which is available in the 
docket for this rulemaking.
3. How do we conduct dispersion modeling, determine inhalation 
exposures, and estimate individual and population inhalation risk?
    Both long-term and short-term inhalation exposure concentrations 
and health risk from the source category addressed in this proposal 
were estimated using the Human Exposure Model, Version 1.5.5(HEM-4).\6\ 
The HEM-4 performs three primary risk assessment activities: (1) 
Conducting dispersion modeling to estimate the concentrations of HAP in 
ambient air, (2) estimating long-term and short-term inhalation 
exposures to individuals residing within 50 kilometers (km) of the 
modeled sources, and (3) estimating individual and population-level 
inhalation risk using the exposure estimates and quantitative dose-
response information.
---------------------------------------------------------------------------

    \6\ For more information about HEM-4, go to https://www.epa.gov/fera/risk-assessment-and-modeling-human-exposure-model-hem.
---------------------------------------------------------------------------

a. Dispersion Modeling
    The air dispersion model AERMOD, used by the HEM-4 model, is one of 
the EPA's preferred models for assessing air pollutant concentrations 
from industrial facilities.\7\ To perform the dispersion

[[Page 1625]]

modeling and to develop the preliminary risk estimates, HEM-4 draws on 
three data libraries. The first is a library of meteorological data, 
which is used for dispersion calculations. This library includes 1 year 
(2016) of hourly surface and upper air observations from 840 
meteorological stations. These stations may include multiple years 
other than meteorological data from 2016. These meteorological stations 
provide coverage of the United States and Puerto Rico. However, for 
this source category, the EPA utilized on-site meteorological data 
(2012-2013) from non-attainment modeling conducted by ADEQ. A second 
library of United States Census Bureau census block \8\ internal point 
locations and populations provides the basis of human exposure 
calculations (U.S. Census, 2010). In addition, for each census block, 
the census library includes the elevation and controlling hill height, 
which are also used in dispersion calculations. A third library of 
pollutant-specific dose-response values is used to estimate health 
risk. These are discussed below.
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    \7\ U.S. EPA. Revision to the Guideline on Air Quality Models: 
Adoption of a Preferred General Purpose (Flat and Complex Terrain) 
Dispersion Model and Other Revisions (70 FR 68218, November 9, 
2005).
    \8\ A census block is the smallest geographic area for which 
census statistics are tabulated.
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b. Risk From Chronic Exposure to HAP
    In developing the risk assessment for chronic exposures, the EPA 
uses the estimated annual average ambient air concentrations of each 
HAP emitted by each source in the source category. The HAP air 
concentrations at each nearby census block centroid located within 50 
km of the facility are a surrogate for the chronic inhalation exposure 
concentration for all the people who reside in that census block. A 
distance of 50 km is consistent with both the analysis supporting the 
1989 Benzene NESHAP (54 FR 38044) and the limitations of Gaussian 
dispersion models, including AERMOD.
    For each facility, the Agency calculates the MIR as the cancer risk 
associated with a continuous lifetime (24 hours per day, 7 days per 
week, 52 weeks per year, 70 years) exposure to the maximum 
concentration at the centroid of each inhabited census block. The EPA 
calculates individual cancer risk by multiplying the estimated lifetime 
exposure to the ambient concentration of each HAP (in micrograms per 
cubic meter ([mu]g/m\3\)) by its unit risk estimate (URE). The URE is 
an upper-bound estimate of an individual's incremental risk of 
contracting cancer over a lifetime of exposure to a concentration of 1 
microgram of the pollutant per cubic meter of air. For residual risk 
assessments, the EPA generally uses UREs from the EPA's Integrated Risk 
Information System (IRIS). For carcinogenic pollutants without IRIS 
values, the EPA looks to other reputable sources of cancer dose-
response values, often using California EPA (CalEPA) UREs, where 
available. In cases where new, scientifically credible dose-response 
values have been developed in a manner consistent with the EPA's 
guidelines and have undergone a similar peer review process, the Agency 
may use such dose-response values in place of, or in addition to, other 
values, if appropriate. The pollutant-specific dose-response values 
used to estimate health risk are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
    Arsenic emissions from this source category are driving cancer 
risks. Inhalation cancer risks are based on an association between 
cumulative arsenic exposure and an increase in lung cancer mortality in 
two distinct smelter worker populations.\9\
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    \9\ US EPA IRIS; Chemical Assessment Summary for Arsenic 
(inorganic) https://cfpub.epa.gov/ncea/iris/iris_documents/documents/subst/0278_summary.pdf#nameddest=cancerinhal.
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    Arsenic is also evaluated for multipathway risks as a PB-HAP based 
upon conservative food ingestions rates (i.e., ingestion of fish and 
produce) and ingestion of contaminated soil.
    To estimate individual lifetime cancer risks associated with 
exposure to HAP emissions from each facility in the source category, 
the Agency sums the risks for each of the carcinogenic HAP \10\ emitted 
by the modeled facility. We estimate cancer risk at every census block 
within 50 km of every facility in the source category. The MIR is the 
highest individual lifetime cancer risk estimated for any of those 
census blocks. In addition to calculating the MIR, we estimate the 
distribution of individual cancer risks for the source category by 
summing the number of individuals within 50 km of the sources whose 
estimated risk falls within a specified risk range. We also estimate 
annual cancer incidence by multiplying the estimated lifetime cancer 
risk at each census block by the number of people residing in that 
block, summing results for all of the census blocks, and then dividing 
this result by a 70-year lifetime.
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    \10\ The EPA's 2005 Guidelines for Carcinogen Risk Assessment 
classifies carcinogens as: ``carcinogenic to humans,'' ``likely to 
be carcinogenic to humans,'' and ``suggestive evidence of 
carcinogenic potential.'' These classifications also coincide with 
the terms ``known carcinogen, probable carcinogen, and possible 
carcinogen,'' respectively, which are the terms advocated in the 
EPA's Guidelines for Carcinogen Risk Assessment, published in 1986 
(51 FR 33992, September 24, 1986). In August 2000, the document, 
Supplemental Guidance for Conducting Health Risk Assessment of 
Chemical Mixtures (EPA/630/R-00/002), was published as a supplement 
to the 1986 document. Copies of both documents can be obtained from 
https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=20533&CFID=70315376&CFTOKEN=71597944. Summing 
the risk of these individual compounds to obtain the cumulative 
cancer risk is an approach that was recommended by the EPA's SAB in 
their 2002 peer review of the EPA's National Air Toxics Assessment 
(NATA) titled NATA--Evaluating the National-scale Air Toxics 
Assessment 1996 Data--an SAB Advisory, available at https://
yosemite.epa.gov/sab/sabproduct.nsf/
214C6E915BB04E14852570CA007A682C/$File/ecadv02001.pdf.
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    To assess the risk of noncancer health effects from chronic 
exposure to HAP, we calculate either an HQ or a target organ-specific 
hazard index (TOSHI). We calculate an HQ when a single noncancer HAP is 
emitted. Where more than one noncancer HAP is emitted, we sum the HQ 
for each of the HAP that affects a common target organ or target organ 
system to obtain a TOSHI. The HQ is the estimated exposure divided by 
the chronic noncancer dose-response value, which is a value selected 
from one of several sources. The preferred chronic noncancer dose-
response value is the EPA RfC, defined as ``an estimate (with 
uncertainty spanning perhaps an order of magnitude) of a continuous 
inhalation exposure to the human population (including sensitive 
subgroups) that is likely to be without an appreciable risk of 
deleterious effects during a lifetime'' (https://iaspub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&vocabName=IRIS%20Glossary). In cases where an RfC 
from the EPA's IRIS is not available or where the EPA determines that 
using a value other than the RfC is appropriate, sometimes the EPA uses 
such an alternative value to assess risks. An example of such an 
alternative value is the use of the primary NAAQS for lead. The lead 
NAAQS is based upon a maximum 3-month average ambient concentration of 
0.15 ug/m3. Additional chronic noncancer dose-response values can be a 
value from the following prioritized sources, which define their dose-
response values similarly to the EPA: (1) The Agency for Toxic 
Substances and Disease Registry (ATSDR) Minimum Risk Level (https://www.atsdr.cdc.gov/mrls/index.asp); (2) the CalEPA Chronic Reference 
Exposure Level (https://oehha.ca.gov/air/crnr/notice-adoption-air-
toxics-hot-spots-program-guidance-manual-preparation-

[[Page 1626]]

health-risk-0); or (3) as noted above, a scientifically credible dose-
response value that has been developed in a manner consistent with the 
EPA guidelines and has undergone a peer review process similar to that 
used by the EPA. The pollutant-specific dose-response values used to 
estimate health risks are available at https://www.epa.gov/fera/dose-response-assessment-assessing-health-risks-associated-exposure-hazardous-air-pollutants.
    This assessment identified emissions of arsenic and lead as a 
chronic noncancer hazard concern for children. Both pollutants impact 
brain development. The chronic, noncancer health effect benchmark for 
arsenic exposure is based on a decrease in intellectual function and 
adverse effects on neurobehavioral development in 10-yr-old children 
exposed through drinking water from birth.\11\
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    \11\ Wasserman et al. (2004) and Tsai et al. (2003).
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    For lead, the NAAQS of 0.15 [micro]g/m\3\ specifies a level of air 
quality that protects the most sensitive subpopulation, children, from 
adverse effects, such as IQ loss, with an adequate margin of safety 
following exposure through inhalation or ingestion of lead previously 
emitted into the air.\12\ Several studies were used as the basis for 
the standard, including an international pooled analysis of seven 
prospective cohort studies (n = 1,333).\13\
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    \12\ EPA Final Rule (National Ambient Air Quality Standards for 
Lead; November 12, 2008); https://www.govinfo.gov/content/pkg/FR-2008-11-12/pdf/E8-25654.pdf.
    \13\ Lanphear et al. (2005).
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    A review of the health effect benchmarks for arsenic and lead 
determined that, although the target organ is the same for these two 
pollutants, a TOSHI should not be calculated based upon the difference 
in exposure duration for the two benchmarks. The chronic REL for 
arsenic is an airborne concentration of inorganic arsenic at or below 
which no adverse noncancer health effects are anticipated in 
individuals indefinitely exposed to that concentration, while the lead 
standard is applied to a maximum 3-month rolling average of monitored 
lead concentrations.
c. Risk From Acute Exposure to HAP That May Cause Health Effects Other 
Than Cancer
    For each HAP for which appropriate acute inhalation dose-response 
values are available, the EPA also assesses the potential health risks 
due to acute exposure. For these assessments, the EPA makes 
conservative assumptions about emission rates, meteorology, and 
exposure location. As part of our efforts to continually improve our 
methodologies to evaluate the risks that HAP emitted from categories of 
industrial sources pose to human health and the environment,\14\ the 
EPA revised our treatment of meteorological data to use reasonable 
worst-case air dispersion conditions in our acute risk screening 
assessments instead of worst-case air dispersion conditions. This 
revised treatment of meteorological data and the supporting rationale 
are described in more detail in Residual Risk Assessment for Primary 
Copper Smelting Major Source Category in Support of the 2021 Risk and 
Technology Review Proposed Rule and in Appendix 5 of the report: 
Technical Support Document for Acute Risk Screening Assessment. This 
revised approach has been used in this proposed rule and in all other 
RTR rulemakings proposed on or after June 3, 2019.
---------------------------------------------------------------------------

    \14\ See, e.g., U.S. EPA. Screening Methodologies to Support 
Risk and Technology Reviews (RTR): A Case Study Analysis (Draft 
Report, May 2017. https://www.epa.gov/stationary-sources-air-pollution/risk-and-technology-review-national-emissions-standards-hazardous).
---------------------------------------------------------------------------

    To assess the potential acute risk to the maximally exposed 
individual, we use the peak hourly emission rate for each emission 
point,\15\ reasonable worst-case air dispersion conditions (i.e., 99th 
percentile), and the point of highest off-site exposure. Specifically, 
we assume that peak emissions from the source category and reasonable 
worst-case air dispersion conditions co-occur and that a person is 
present at the point of maximum exposure.
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    \15\ In the absence of hourly emission data, the EPA develops 
estimates of maximum hourly emission rates by multiplying the 
average actual annual emissions rates by a factor (either a 
category-specific factor or a default factor of 10) to account for 
variability. This is documented in Residual Risk Assessment for 
Primary Copper Smelting Major Source Category in Support of the 2020 
Risk and Technology Review Proposed Rule and in Appendix 5 of the 
report: Technical Support Document for Acute Risk Screening 
Assessment. Both are available in the docket for this rulemaking.
---------------------------------------------------------------------------

    To characterize the potential health risks associated with 
estimated acute inhalation exposures to a HAP, we generally use 
multiple acute dose-response values, including acute RELs, acute 
exposure guideline levels (AEGLs), and emergency response planning 
guidelines (ERPG) for 1-hour exposure durations, if available, to 
calculate acute HQs. The acute HQ is calculated by dividing the 
estimated acute exposure concentration by the acute dose-response 
value. For each HAP for which acute dose-response values are available, 
the EPA calculates acute HQs. For this source category, acute risks 
from arsenic were a concern based upon the 1-hour REL of 0.2 [mu]g/
m\3\. The acute REL is based on developmental effects in mice 
(decreased fetal weight, growth retardation, skeletal defects).\16\
---------------------------------------------------------------------------

    \16\ Nagymajtenyi et al. 1985.
---------------------------------------------------------------------------

    An acute REL is defined as ``the concentration level at or below 
which no adverse health effects are anticipated for a specified 
exposure duration.'' \17\ Acute RELs are based on the most sensitive, 
relevant, adverse health effect reported in the peer-reviewed medical 
and toxicological literature. They are designed to protect the most 
sensitive individuals in the population through the inclusion of 
margins of safety. Because margins of safety are incorporated to 
address data gaps and uncertainties, exceeding the REL does not 
automatically indicate an adverse health impact. AEGLs represent 
threshold exposure limits for the general public and are applicable to 
emergency exposures ranging from 10 minutes to 8 hours.\18\ They are 
guideline levels for ``once-in-a-lifetime, short-term exposures to 
airborne concentrations of acutely toxic, high-priority chemicals.'' 
Id. at 21. The AEGL-1 is specifically defined as ``the airborne 
concentration (expressed as ppm (parts per million) or mg/m\3\ 
(milligrams per cubic meter)) of a substance above which it is 
predicted that the general population, including susceptible 
individuals, could experience notable discomfort, irritation, or 
certain asymptomatic nonsensory effects. However, the effects are not 
disabling and are transient and reversible upon cessation of 
exposure.'' Id. at 3. The document also notes that ``Airborne 
concentrations below AEGL-1 represent exposure levels that can produce 
mild and progressively increasing but transient and nondisabling odor, 
taste, and sensory irritation or certain asymptomatic, nonsensory 
effects.'' Id. AEGL-2 are defined as ``the airborne concentration 
(expressed as parts per million or

[[Page 1627]]

milligrams per cubic meter) of a substance above which it is predicted 
that the general population, including susceptible individuals, could 
experience irreversible or other serious, long-lasting adverse health 
effects or an impaired ability to escape.'' Id.
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    \17\ CalEPA issues acute RELs as part of its Air Toxics Hot 
Spots Program, and the 1-hour and 8-hour values are documented in 
Air Toxics Hot Spots Program Risk Assessment Guidelines, Part I, The 
Determination of Acute Reference Exposure Levels for Airborne 
Toxicants, which is available at https://oehha.ca.gov/air/general-info/oehha-acute-8-hour-and-chronic-reference-exposure-level-rel-summary.
    \18\ National Academy of Sciences, 2001. Standing Operating 
Procedures for Developing Acute Exposure Levels for Hazardous 
Chemicals, page 2. Available at https://www.epa.gov/sites/production/files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. Note that the 
National Advisory Committee for Acute Exposure Guideline Levels for 
Hazardous Substances ended in October 2011, but the AEGL program 
continues to operate at the EPA and works with the National 
Academies to publish final AEGLs (https://www.epa.gov/aegl).
---------------------------------------------------------------------------

    ERPGs are ``developed for emergency planning and are intended as 
health-based guideline concentrations for single exposures to 
chemicals.'' \19\ Id. at 1. The ERPG-1 is defined as ``the maximum 
airborne concentration below which it is believed that nearly all 
individuals could be exposed for up to 1 hour without experiencing 
other than mild transient adverse health effects or without perceiving 
a clearly defined, objectionable odor.'' Id. at 2. Similarly, the ERPG-
2 is defined as ``the maximum airborne concentration below which it is 
believed that nearly all individuals could be exposed for up to one 
hour without experiencing or developing irreversible or other serious 
health effects or symptoms which could impair an individual's ability 
to take protective action.'' Id. at 1.
---------------------------------------------------------------------------

    \19\ ERPGS Procedures and Responsibilities. March 2014. American 
Industrial Hygiene Association. Available at: https://www.aiha.org/get-involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERPG%20Committee%20Standard%20Operating%20Procedures%20%20-%20March%202014%20Revision%20%28Updated%2010-2-2014%29.pdf.
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    An acute REL for 1-hour exposure durations is typically lower than 
its corresponding AEGL-1 and ERPG-1. Even though their definitions are 
slightly different, AEGL-1s are often the same as the corresponding 
ERPG-1s, and AEGL-2s are often equal to ERPG-2s. The maximum HQs from 
our acute inhalation screening risk assessment typically result when we 
use the acute REL for a HAP. In cases where the maximum acute HQ 
exceeds 1, we also report the HQ based on the next highest acute dose-
response value (usually the AEGL-1 and/or the ERPG-1).
    For this source category, we developed source category-specific 
acute factors ranging from 3 to 10 to estimate peak hourly emissions 
from annual emissions estimates for the input to the acute risk 
assessment modeling analysis. In general, hourly emissions estimates 
were based on batch cycle times for smelting and anode furnaces with an 
emission hourly multiplier of 3 applied while road fugitive emissions 
were modeled with a default hourly multiplier of 10 times the annual 
average. A further discussion of these factors and why they were chosen 
can be found in the memorandum, Emissions Data Used for Primary Copper 
Smelting Risk and Technology Review (RTR) Modeling Files, available in 
the docket for this rulemaking.
    In our acute inhalation screening risk assessment, acute impacts 
are deemed negligible for HAP for which acute HQs are less than or 
equal to 1, and no further analysis is performed for these HAP. In 
cases where an acute HQ from the screening step is greater than 1, we 
assess the site-specific data to ensure that the acute HQ is at an off-
site location. For this source category, the data refinements employed 
consisted of overlaying satellite imagery with off-site polar receptors 
to estimate off-site acute impacts. These refinements are discussed 
more fully in the Residual Risk Assessment for the Primary Copper 
Smelting Major Source Category in Support of the 2021 Risk and 
Technology Review Proposed Rule, which is available in the docket for 
this source category.
4. How do we conduct the multipathway exposure and risk screening 
assessment?
    The EPA conducts a tiered screening assessment examining the 
potential for significant human health risks due to exposures via 
routes other than inhalation (i.e., ingestion). We first determine 
whether any sources in the source category emit any HAP known to be 
persistent and bioaccumulative in the environment, as identified in the 
EPA's Air Toxics Risk Assessment Library (see Volume 1, Appendix D, at 
https://www.epa.gov/fera/risk-assessment-and-modeling-air-toxics-risk-assessment-reference-library).
    For the Primary Copper Smelting source category, we identified PB-
HAP emissions of lead, arsenic, mercury and cadmium, so we proceeded to 
the next step of the evaluation. Except for lead, the human health risk 
screening assessment for PB-HAP consists of three progressive tiers. In 
a Tier 1 screening assessment, we determine whether the magnitude of 
the facility-specific emissions of PB-HAP warrants further evaluation 
to characterize human health risk through upper-end ingestion rates of 
(meat, produce, fruits, fish, etc.) based upon a combined farmer and 
fisher scenario. To facilitate this step, we evaluate emissions against 
previously developed screening threshold emission rates for several PB-
HAP that are based on a hypothetical upper-end screening exposure 
scenario developed for use in conjunction with the EPA's Total Risk 
Integrated Methodology.Fate, Transport, and Ecological Exposure 
(TRIM.FaTE) model. The PB-HAP with screening threshold emission rates 
are arsenic compounds, cadmium compounds, chlorinated dibenzodioxins 
and furans, mercury compounds, and polycyclic organic matter (POM). 
Based on the EPA estimates of toxicity and bioaccumulation potential, 
these pollutants represent a conservative list for inclusion in 
multipathway risk assessments for RTR rules. (For more details see the 
risk assessment report cited above and Volume 1, Appendix D at https://www.epa.gov/sites/production/files/2013-08/documents/volume_1_reflibrary.pdf.). In this assessment, we compare the facility-
specific emission rates of these PB-HAP to the screening threshold 
emission rates for each PB-HAP to assess the potential for significant 
human health risks via the ingestion pathway. We call this application 
of the TRIM.FaTE model the Tier 1 screening assessment. The ratio of a 
facility's actual emission rate to the Tier 1 screening threshold 
emission rate is a screening value (SV).
    We derive the Tier 1 screening threshold emission rates for these 
PB-HAP (other than lead compounds) to correspond to a maximum excess 
lifetime cancer risk of 1-in-1 million (i.e., for arsenic compounds, 
polychlorinated dibenzodioxins and furans, and POM) or, for HAP that 
cause noncancer health effects (i.e., cadmium compounds and mercury 
compounds), a maximum HQ of 1. If the emission rate of any one PB-HAP 
or combination of carcinogenic PB-HAP in the Tier 1 screening 
assessment exceeds the Tier 1 screening threshold emission rate for any 
facility (i.e., the SV is greater than 1), we conduct a second 
screening assessment, which we call the Tier 2 screening assessment. 
The Tier 2 screening assessment separates the Tier 1 combined fisher 
and farmer exposure scenario into fisher, farmer, and gardener 
scenarios that retain upper-bound ingestion rates.
    In the Tier 2 screening assessment, the location of each facility 
that exceeds a Tier 1 screening threshold emission rate is used to 
refine the assumptions associated with the Tier 1 fisher and farmer 
exposure scenarios at that facility. A key assumption in the Tier 1 
screening assessment is that a lake and/or farm is located near the 
facility. As part of the Tier 2 screening assessment, we use a U.S. 
Geological Survey (USGS) database to identify actual waterbodies within 
50 km of each facility and assume the fisher only consumes fish from 
lakes within that 50 km zone. We also examine the differences between 
local meteorology near the facility and the meteorology used in the 
Tier 1 screening assessment. We then adjust the previously developed 
Tier 1

[[Page 1628]]

screening threshold emission rates for each PB-HAP for each facility 
based on an understanding of how exposure concentrations estimated for 
the screening scenario change with the use of local meteorology and the 
USGS lakes database.
    In the Tier 2 farmer scenario, we maintain an assumption that the 
farm is located within 0.5 km of the facility and that the farmer 
consumes meat, eggs, dairy, vegetables, and fruit produced near the 
facility. We may further refine the Tier 2 screening analysis by 
assessing a gardener scenario to characterize a range of exposures, 
with the gardener scenario being more plausible in RTR evaluations. 
Under the gardener scenario, we assume the gardener consumes home-
produced eggs, vegetables, and fruit products at the same ingestion 
rate as the farmer. The Tier 2 screen continues to rely on the high-end 
food intake assumptions that were applied in Tier 1 for local fish 
(adult female angler at 99th percentile fish consumption \20\) and 
locally grown or raised foods (90th percentile consumption of locally 
grown or raised foods for the farmer and gardener scenarios \21\). If 
PB-HAP emission rates do not result in a Tier 2 SV greater than 1, we 
consider those PB-HAP emissions to pose risks below a level of concern. 
If the PB-HAP emission rates for a facility exceed the Tier 2 screening 
threshold emission rates, we may conduct a Tier 3 screening assessment.
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    \20\ Burger, J. 2002. Daily consumption of wild fish and game: 
Exposures of high end recreationists. International Journal of 
Environmental Health Research, 12:343-354.
    \21\ U.S. EPA. Exposure Factors Handbook 2011 Edition (Final). 
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/
052F, 2011.
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    There are several analyses that can be included in a Tier 3 
screening assessment, depending upon the extent of refinement 
warranted, including validating that the lakes are fishable, locating 
residential/garden locations for urban and/or rural settings, 
considering plume-rise to estimate emissions lost above the mixing 
layer, and considering hourly effects of meteorology and plume-rise on 
chemical fate and transport (a time-series analysis). If necessary, the 
EPA may further refine the screening assessment through a site-specific 
assessment.
    In evaluating the potential multipathway risk from emissions of 
lead compounds, rather than developing a screening threshold emission 
rate, the Agency compares maximum estimated chronic inhalation exposure 
concentrations to the level of the current NAAQS for lead.\22\ Values 
below the level of the primary (health-based) lead NAAQS are considered 
to have a low potential for multipathway risk. For this source category 
based upon high modeled annual concentrations of lead from HEM-4, a 
refined assessment was conducted to estimate the maximum 3-month 
average concentration for lead over multiple years. These refinements 
included the use of a post-processer (Lead-POST) in AERMOD to calculate 
the maximum 3-month lead concentration for each off-site receptor to 
directly compare to the current lead NAAQS standard.\23\
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    \22\ In doing so, the EPA notes that the legal standard for a 
primary NAAQS--that a standard is requisite to protect public health 
and provide an adequate margin of safety (CAA section 109(b))--
differs from the CAA section 112(f) standard (requiring, among other 
things, that the standard provide an ``ample margin of safety to 
protect public health''). However, the primary lead NAAQS is a 
reasonable measure of determining risk acceptability (i.e., the 
first step of the Benzene NESHAP analysis) since it is designed to 
protect the most susceptible group in the human population--
children, including children living near major lead emitting 
sources. 73 FR 67002/3; 73 FR 67000/3; 73 FR 67005/1. In addition, 
applying the level of the primary lead NAAQS at the risk 
acceptability step is conservative since that primary lead NAAQS 
reflects an adequate margin of safety.
    \23\ EPA Support Center for Regulatory Atmospheric Modeling site 
to access LEADPOST utilized in the Pb NAAQS program: https://www.epa.gov/scram/air-quality-dispersion-modeling-preferred-and-recommended-models.
---------------------------------------------------------------------------

    For further information on the multipathway assessment approach, 
see the Residual Risk Assessment for the Primary Copper Smelting Major 
Source Category in Support of the Risk and Technology Review 2021 
Proposed Rule, which is available in the docket for this action.
5. How do we assess risks considering emissions control options?
    In addition to assessing baseline inhalation risks and screening 
for potential multipathway risks, the EPA also estimates risks 
considering the potential emission reductions that would be achieved by 
the control options under consideration. In these cases, the expected 
emission reductions are applied to the specific HAP and emission points 
in the RTR emissions dataset to develop corresponding estimates of risk 
and incremental risk reductions.
6. How do we conduct the environmental risk screening assessment?
a. Adverse Environmental Effect, Environmental HAP, and Ecological 
Benchmarks
    The EPA conducts a screening assessment to examine the potential 
for an adverse environmental effect as required under section 
112(f)(2)(A) of the CAA. Section 112(a)(7) of the CAA defines ``adverse 
environmental effect'' as ``any significant and widespread adverse 
effect, which may reasonably be anticipated, to wildlife, aquatic life, 
or other natural resources, including adverse impacts on populations of 
endangered or threatened species or significant degradation of 
environmental quality over broad areas.''
    The EPA focuses on eight HAP, which are referred to as 
``environmental HAP,'' in its screening assessment: Six PB-HAP and two 
acid gases. The PB-HAP included in the screening assessment are arsenic 
compounds, cadmium compounds, dioxins/furans, POM, mercury (both 
inorganic mercury and methyl mercury), and lead compounds. The acid 
gases included in the screening assessment are hydrochloric acid (HCl) 
and hydrogen fluoride (HF).
    HAP that persist and bioaccumulate are of particular environmental 
concern because they accumulate in the soil, sediment, and water. The 
acid gases, HCl and HF, are included due to their well-documented 
potential to cause direct damage to terrestrial plants. In the 
environmental risk screening assessment, the EPA evaluates the 
following four exposure media: terrestrial soils, surface water bodies 
(includes water-column and benthic sediments), fish consumed by 
wildlife, and air. Within these four exposure media, the Agency 
evaluates nine ecological assessment endpoints, which are defined by 
the ecological entity and its attributes. For PB-HAP (other than lead), 
both community-level and population-level endpoints are included. For 
acid gases, the ecological assessment endpoint evaluated is terrestrial 
plant communities.
    An ecological benchmark represents a concentration of HAP that has 
been linked to a particular environmental effect level. For each 
environmental HAP, the Agency identified the available ecological 
benchmarks for each assessment endpoint and where possible, the 
ecological benchmarks at the following effect levels: probable effect 
levels, lowest-observed-adverse-effect level, and no-observed-adverse-
effect level. In cases where multiple effect levels were available for 
a particular PB-HAP and assessment endpoint, the EPA uses all of the 
available effect levels to help us to determine whether ecological 
risks exist and, if so, whether the risks could be considered 
significant and widespread.
    For further information on how the environmental risk screening

[[Page 1629]]

assessment was conducted, including a discussion of the risk metrics 
used, how the environmental HAP were identified, and how the ecological 
benchmarks were selected, see Appendix 9 of the Residual Risk 
Assessment for the Primary Copper Smelting Major Source Category in 
Support of the Risk and Technology Review 2021 Proposed Rule, which is 
available in the docket for this action.
b. Environmental Risk Screening Methodology
    For the environmental risk screening assessment, the EPA first 
determined whether any facilities in the Primary Copper Smelting source 
category emitted any of the environmental HAP. For the Primary Copper 
Smelting source category, the Agency identified emissions of arsenic, 
mercury, cadmium and lead. Because one or more of the environmental HAP 
evaluated are emitted by at least one facility in the source category, 
the Agency proceeded to the second step of the evaluation.
c. PB-HAP Methodology for Environmental Risk Screening
    The environmental risk screening assessment includes six PB-HAP: 
Arsenic compounds, cadmium compounds, dioxins/furans, POM, mercury 
(both inorganic mercury and methyl mercury), and lead compounds. With 
the exception of lead, the environmental risk screening assessment for 
PB-HAP consists of three tiers. The first tier of the environmental 
risk screening assessment uses the same health-protective conceptual 
model that is used for the Tier 1 human health screening assessment. 
TRIM.FaTE model simulations were used to back-calculate Tier 1 
screening threshold emission rates. The screening threshold emission 
rates represent the emission rate in tons of pollutant per year that 
results in media concentrations at the facility that equal the relevant 
ecological benchmark. To assess emissions from each facility in the 
category, the reported emission rate for each PB-HAP was compared to 
the Tier 1 screening threshold emission rate for that PB-HAP for each 
assessment endpoint and effect level. If emissions from a facility do 
not exceed the Tier 1 screening threshold emission rate, the facility 
``passes'' the screening assessment, and, therefore, is not evaluated 
further under the screening approach. If emissions from a facility 
exceed the Tier 1 screening threshold emission rate, the EPA evaluates 
the facility further in Tier 2.
    In Tier 2 of the environmental risk screening assessment, the 
screening threshold emission rates are adjusted to account for local 
meteorology and the actual location of lakes in the vicinity of 
facilities that did not pass the Tier 1 screening assessment. For 
soils, the EPA evaluates the average soil concentration for all soil 
parcels within a 7.5-km radius for each facility and PB-HAP. For the 
water, sediment, and fish tissue concentrations, the highest value for 
each facility for each pollutant is used. If emission concentrations 
from a facility do not exceed the Tier 2 screening threshold emission 
rate, the facility ``passes'' the screening assessment and typically is 
not evaluated further. If emissions from a facility exceed the Tier 2 
screening threshold emission rate, the EPA evaluates the facility 
further in Tier 3.
    As in the multipathway human health risk assessment, in Tier 3 of 
the environmental risk screening assessment, the Agency examines the 
suitability of the lakes around the facilities to support life and 
remove those that are not suitable (e.g., lakes that have been filled 
in or are industrial ponds), adjust emissions for plume-rise, and 
conduct hour-by-hour time-series assessments. If these Tier 3 
adjustments to the screening threshold emission rates still indicate 
the potential for an adverse environmental effect (i.e., facility 
emission rate exceeds the screening threshold emission rate), the 
Agency may elect to conduct a more refined assessment using more site-
specific information. If, after additional refinement, the facility 
emission rate still exceeds the screening threshold emission rate, the 
facility may have the potential to cause an adverse environmental 
effect.
    To evaluate the potential for an adverse environmental effect from 
lead, we compared the average modeled air concentrations (from HEM-4) 
of lead around each facility in the source category to the level of the 
secondary NAAQS for lead. The secondary lead NAAQS is a reasonable 
means of evaluating environmental risk because it is set to provide 
substantial protection against adverse welfare effects which can 
include ``effects on soils, water, crops, vegetation, man-made 
materials, animals, wildlife, weather, visibility and climate, damage 
to and deterioration of property, and hazards to transportation, as 
well as effects on economic values and on personal comfort and well-
being.''
d. Acid Gas Environmental Risk Methodology
    The environmental risk screening assessment for acid gases 
evaluates the potential phytotoxicity and reduced productivity of 
plants due to chronic exposure to HF and HCl. The environmental risk 
screening methodology for acid gases is a single-tier screening 
assessment that compares modeled ambient air concentrations (from 
AERMOD) to the ecological benchmarks for each acid gas. To identify a 
potential adverse environmental effect (as defined in section 112(a)(7) 
of the CAA) from emissions of HF and HCl, the Agency evaluates the 
following metrics: the size of the modeled area around each facility 
that exceeds the ecological benchmark for each acid gas, in acres and 
square kilometers; the percentage of the modeled area around each 
facility that exceeds the ecological benchmark for each acid gas; and 
the area-weighted average SV around each facility (calculated by 
dividing the area-weighted average concentration over the 50-km 
modeling domain by the ecological benchmark for each acid gas). For 
further information on the environmental screening assessment approach, 
see Appendix 9 of the Residual Risk Assessment for the Primary Copper 
Smelting Major Source Category in Support of the Risk and Technology 
Review 20201 Proposed Rule, which is available in the docket for this 
action.
7. How do we conduct facility-wide assessments?
    To put the source category risks in context, the EPA typically 
examines the risks from the entire ``facility,'' where the facility 
includes all HAP-emitting operations within a contiguous area and under 
common control. In other words, the Agency examines the HAP emissions 
not only from the source category emission points of interest, but also 
emissions of HAP from all other emission sources at the facility for 
which we have data. For this source category, we conducted the 
facility-wide assessment using a dataset compiled from the 2017 NEI and 
2018 actual emissions provided by ADEQ. The source category records of 
that 2017 and 2018 actual emissions dataset were removed, evaluated, 
and updated as described in section II.C of this preamble: What data 
collection activities were conducted to support this action? Once a 
quality assured source category dataset was available, it was placed 
back with the remaining records from the NEI for that facility. The 
facility-wide file was then used to analyze risks due to the inhalation 
of HAP that are emitted ``facility-wide'' for the populations residing 
within 50 km of each facility, consistent with the methods used for the 
source category analysis described above. For these

[[Page 1630]]

facility-wide risk analyses, the modeled source category risks were 
compared to the facility-wide risks to determine the portion of the 
facility-wide risks that could be attributed to the source category 
addressed in this proposal. The EPA also specifically examined the 
facility that was associated with the highest estimate of risk and 
determined the percentage of that risk attributable to the source 
category of interest. The Residual Risk Assessment for the Primary 
Copper Smelting Major Source Category in Support of the Risk and 
Technology Review 20201 Proposed Rule, available through the docket for 
this action, provides the methodology and results of the facility-wide 
analyses, including all facility-wide risks and the percentage of 
source category contribution to facility-wide risks.
8. How do we consider uncertainties in risk assessment?
    Uncertainty and the potential for bias are inherent in all risk 
assessments, including those performed for this proposal. Although 
uncertainty exists, we believe that our approach, which used 
conservative tools and assumptions, ensures that our decisions are 
health and environmentally protective. A brief discussion of the 
uncertainties in the RTR emissions dataset, dispersion modeling, 
inhalation exposure estimates, and dose-response relationships follows 
below. Also included are those uncertainties specific to our acute 
screening assessments, multipathway screening assessments, and our 
environmental risk screening assessments. A more thorough discussion of 
these uncertainties is included in the Residual Risk Assessment for the 
Primary Copper Smelting Major Source Category in Support of the Risk 
and Technology Review 2021 Proposed Rule, which is available in the 
docket for this action. If a multipathway site-specific assessment was 
performed for this source category, a full discussion of the 
uncertainties associated with that assessment can be found in Appendix 
11 of that document, Site-Specific Human Health Multipathway Residual 
Risk Assessment Report.
a. Uncertainties in the RTR Emissions Dataset
    Although the development of the RTR emissions dataset involved 
quality assurance/quality control processes, the accuracy of emissions 
values will vary depending on the source of the data, the degree to 
which data are incomplete or missing, the degree to which assumptions 
made to complete the datasets are accurate, errors in emission 
estimates, and other factors. The emission estimates considered in this 
analysis generally are annual totals for certain years, and they 
generally do not reflect short-term fluctuations during the course of a 
year or variations from year to year except in potentially a few cases, 
such as the May/June 2018 lead test data for anode refining roof vent 
fugitive emissions from the Freeport facility. Nevertheless, the 
estimates of peak hourly emission rates for the acute effects screening 
assessment were based on emission adjustment factors applied to the 
average annual hourly emission rates, which are intended to account for 
emission fluctuations due to normal facility operations.
b. Uncertainties in Dispersion Modeling
    The EPA recognizes there is uncertainty in ambient concentration 
estimates associated with any model, including the EPA's recommended 
regulatory dispersion model, AERMOD. In using a model to estimate 
ambient pollutant concentrations, the user chooses certain options to 
apply. For RTR assessments, we select some model options that have the 
potential to overestimate ambient air concentrations (e.g., not 
including plume depletion or pollutant transformation). We select other 
model options that have the potential to underestimate ambient impacts 
(e.g., not including building downwash). Other options that we select 
have the potential to either under- or overestimate ambient levels 
(e.g., location and year of meteorology data and receptor locations). 
On balance, considering the directional nature of the uncertainties 
commonly present in ambient concentrations estimated by dispersion 
models, the approach we apply in the RTR assessments should yield 
unbiased estimates of ambient HAP concentrations. The uncertainties 
attributed to dispersion modeling in RTR assessments were assessed by 
EPA's Science Advisory Board (SAB) and deemed suitable and 
appropriate.\24\ We also note that the selection of meteorology dataset 
location could have an impact on the risk estimates. For this source 
category, the two facilities being modeled have ambient air toxics 
monitors and on-site meteorological stations in place that can be used 
to help characterize the uncertainty of the emissions modeling. For the 
Freeport facility, we were unable to collect on-site meteorological 
data for the 2019 monitor to model comparison; therefore, the model to 
monitor evaluation was based upon on-site 2011-2012 meteorological data 
with the 2019 monitoring data. This was not an uncertainty for the 
Asarco facility, since both model and monitoring comparisons were for 
2019. A review of the model to monitor comparisons between the two 
site(s) can be found in Appendix 1 of the Residual Risk Assessment for 
the Primary Copper Smelting Source Category in Support of the Risk and 
Technology Review 2021 Proposed Rule, report which is available in the 
docket for this action and Section IV; B-6 of this proposal. As we 
continue to update and expand our library of meteorological station 
data used in our risk assessments, we expect to reduce this 
variability.
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    \24\ USEPA, 2009a. Risk and Technology Review (RTR) Risk 
Assessment Methodologies: For Review by the EPA's Science Advisory 
Board with Case Studies--MACT I Petroleum Refining Sources and 
Portland Cement Manufacturing. EPA-452/R-09-006. https://
yosemite.epa.gov/sab/sabproduct.nsf/
4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-unsigned.pdf.
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c. Uncertainties in Inhalation Exposure Assessment
    Although every effort is made to identify all of the relevant 
facilities and emission points, as well as to develop accurate 
estimates of the annual emission rates for all relevant HAP, the 
uncertainties in our emission inventory likely dominate the 
uncertainties in the exposure assessment. Some uncertainties in our 
exposure assessment include human mobility, using the centroid of each 
census block, assuming lifetime exposure, and assuming only outdoor 
exposures. For most of these factors, there is neither an under nor 
overestimate when looking at the maximum individual risk or the 
incidence, but the shape of the distribution of risks may be affected. 
With respect to outdoor exposures, actual exposures may not be as high 
if people spend time indoors, especially for very reactive pollutants 
or larger particles. For all factors, we reduce uncertainty when 
possible. For example, with respect to census-block centroids, we 
analyze large blocks using aerial imagery and adjust locations of the 
block centroids to better represent the population in the blocks. We 
also add additional receptor locations where the population of a block 
is not well represented by a single location.
d. Uncertainties in Dose-Response Relationships
    There are uncertainties inherent in the development of the dose-
response values used in our risk assessments for cancer effects from 
chronic exposures and noncancer effects from both chronic and acute 
exposures. Some uncertainties are generally expressed quantitatively, 
and others are generally

[[Page 1631]]

expressed in qualitative terms. We note, as a preface to this 
discussion, a point on dose-response uncertainty that is stated in the 
EPA's 2005 Guidelines for Carcinogen Risk Assessment; namely, that 
``the primary goal of EPA actions is protection of human health; 
accordingly, as an Agency policy, risk assessment procedures, including 
default options that are used in the absence of scientific data to the 
contrary, should be health protective'' (the EPA's 2005 Guidelines for 
Carcinogen Risk Assessment, page 1-7). This is the approach followed 
here as summarized in the next paragraphs.
    Cancer UREs used in our risk assessments are those that have been 
developed to generally provide an upper bound estimate of risk.\25\ 
That is, they represent a ``plausible upper limit to the true value of 
a quantity'' (although this is usually not a true statistical 
confidence limit). In some circumstances, the true risk could be as low 
as zero; however, in other circumstances the risk could be greater.\26\ 
Chronic noncancer RfC and reference dose values represent chronic 
exposure levels that are intended to be health-protective levels. To 
derive dose-response values that are intended to be ``without 
appreciable risk,'' the methodology relies upon an uncertainty factor 
(UF) approach,\27\ which considers uncertainty, variability, and gaps 
in the available data. The UFs are applied to derive dose-response 
values that are intended to protect against appreciable risk of 
deleterious effects.
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    \25\ IRIS glossary (https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?details=&glossaryName=IRIS%20Glossary).
    \26\ An exception to this is the URE for benzene, which is 
considered to cover a range of values, each end of which is 
considered to be equally plausible, and which is based on maximum 
likelihood estimates.
    \27\ See A Review of the Reference Dose and Reference 
Concentration Processes, U.S. EPA, December 2002, and Methods for 
Derivation of Inhalation Reference Concentrations and Application of 
Inhalation Dosimetry, U.S. EPA, 1994.
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    Many of the UFs used to account for variability and uncertainty in 
the development of acute dose-response values are quite similar to 
those developed for chronic durations. Additional adjustments are often 
applied to account for uncertainty in extrapolation from observations 
at one exposure duration (e.g., 4 hours) to derive an acute dose-
response value at another exposure duration (e.g., 1 hour). Not all 
acute dose-response values are developed for the same purpose, and care 
must be taken when interpreting the results of an acute assessment of 
human health effects relative to the dose-response value or values 
being exceeded. Where relevant to the estimated exposures, the lack of 
acute dose-response values at different levels of severity should be 
factored into the risk characterization as potential uncertainties.
    Uncertainty also exists in the selection of ecological benchmarks 
for the environmental risk screening assessment. The EPA established a 
hierarchy of preferred benchmark sources to allow selection of 
benchmarks for each environmental HAP at each ecological assessment 
endpoint. We searched for benchmarks for three effect levels (i.e., no-
effects level, threshold-effect level, and probable effect level), but 
not all combinations of ecological assessment/environmental HAP had 
benchmarks for all three effect levels. Where multiple effect levels 
were available for a particular HAP and assessment endpoint, we used 
all of the available effect levels to help us determine whether risk 
exists and whether the risk could be considered significant and 
widespread.
    For a group of compounds that are unspeciated (e.g., glycol 
ethers), we conservatively use the most protective dose-response value 
of an individual compound in that group to estimate risk. Similarly, 
for an individual compound in a group (e.g., ethylene glycol diethyl 
ether) that does not have a specified dose-response value, we also 
apply the most protective dose-response value from the other compounds 
in the group to estimate risk.
e. Uncertainties in Acute Inhalation Screening Assessments
    In addition to the uncertainties highlighted above, there are 
several factors specific to the acute exposure assessment that the EPA 
conducts as part of the risk review under section 112 of the CAA. The 
accuracy of an acute inhalation exposure assessment depends on the 
simultaneous occurrence of independent factors that may vary greatly, 
such as hourly emissions rates, meteorology, and the presence of a 
person. In the acute screening assessment that we conduct under the RTR 
program, we assume that peak emissions from the source category and 
reasonable worst-case air dispersion conditions (i.e., 99th percentile) 
co-occur. We then include the additional assumption that a person is 
located at this point at the same time. Together, these assumptions 
represent a reasonable worst-case actual exposure scenario. In most 
cases, it is unlikely that a person would be located at the point of 
maximum exposure during the time when peak emissions and reasonable 
worst-case air dispersion conditions occur simultaneously.
f. Uncertainties in the Multipathway and Environmental Risk Screening 
Assessments
    For each source category, the Agency generally relies on site-
specific levels of PB-HAP or environmental HAP emissions to determine 
whether a refined assessment of the impacts from multipathway exposures 
is necessary or whether it is necessary to perform an environmental 
screening assessment. This determination is based on the results of a 
three-tiered screening assessment that relies on the outputs from 
models--TRIM.FaTE and AERMOD--that estimate environmental pollutant 
concentrations and human exposures for five PB-HAP (dioxins, POM, 
mercury, cadmium, and arsenic) and two acid gases (HF and HCl). For 
lead, the Agency uses AERMOD to determine ambient air concentrations, 
which are then compared to the secondary NAAQS standard for lead. Two 
important types of uncertainty associated with the use of these models 
in RTR risk assessments and inherent to any assessment that relies on 
environmental modeling are model uncertainty and input uncertainty.\28\
---------------------------------------------------------------------------

    \28\ In the context of this discussion, the term ``uncertainty'' 
as it pertains to exposure and risk encompasses both variability in 
the range of expected inputs and screening results due to existing 
spatial, temporal, and other factors, as well as uncertainty in 
being able to accurately estimate the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the model adequately represents 
the actual processes (e.g., movement and accumulation) that might occur 
in the environment. For example, does the model adequately describe the 
movement of a pollutant through the soil? This type of uncertainty is 
difficult to quantify. However, based on feedback received from 
previous EPA SAB reviews and other reviews, we are confident that the 
models used in the screening assessments are appropriate and state-of-
the-art for the multipathway and environmental screening risk 
assessments conducted in support of RTRs. For example, the SAB found 
that the general methodology of the tiered screening approach and the 
use of TRIM.FaTE and AERMOD are appropriate for both multipathway and 
ecological screening tools. The SAB noted the simplicity of the air 
dispersion treatment in TRIM.FaTE and encouraged the advancement of

[[Page 1632]]

incorporating AERMOD analysis within the TRIM.FaTE framework.\29\
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    \29\ USEPA, 2018. Review of EPA's draft technical report entitle 
Screening Methodologies to Support Risk and Technology Review (RTR): 
A Case Study Analysis; EPA-SAB-18-004. https://yosemite.epa.gov/sab/
sabproduct.nsf/LookupWebReportsLastMonthBOARD/
7A84AADF3F2FE04A85258307005F7D70/$File/EPA-SAB-18-004+.pdf.
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    Input uncertainty is concerned with how accurately the models have 
been configured and parameterized for the assessment at hand. For Tier 
1 of the multipathway and environmental screening assessments, the EPA 
configured the models to avoid underestimating exposure and risk. This 
was accomplished by selecting upper-end values from nationally 
representative datasets for the more influential parameters in the 
environmental model, including selection and spatial configuration of 
the area of interest, lake location and size, meteorology, surface 
water, soil characteristics, and structure of the aquatic food web. The 
EPA also assumes an ingestion exposure scenario and values for human 
exposure factors that represent reasonable maximum exposures.
    In Tier 2 of the multipathway and environmental screening 
assessments, we refine the model inputs to account for meteorological 
patterns in the vicinity of the facility versus using upper-end 
national values, and we identify the actual location of lakes near the 
facility rather than the default lake location that we apply in Tier 1. 
By refining the screening approach in Tier 2 to account for local 
geographical and meteorological data, we decrease the likelihood that 
concentrations in environmental media are overestimated, thereby 
increasing the usefulness of the screening assessment. In Tier 3 of the 
screening assessments, we refine the model inputs again to account for 
hour-by-hour plume-rise and the height of the mixing layer. The EPA can 
also use those hour-by-hour meteorological data in a TRIM.FaTE run 
using the screening configuration corresponding to the lake location. 
These refinements produce a more accurate estimate of chemical 
concentrations in the media of interest, thereby reducing the 
uncertainty with those estimates. The assumptions and the associated 
uncertainties regarding the selected ingestion exposure scenario are 
the same for all three tiers.
    For the environmental screening assessment for acid gases, we 
employ a single-tiered approach. We use the modeled air concentrations 
and compare those with ecological benchmarks.
    For all tiers of the multipathway and environmental screening 
assessments, our approach to addressing model input uncertainty is 
generally cautious. We choose model inputs from the upper end of the 
range of possible values for the influential parameters used in the 
models, and we assume that the exposed individual exhibits ingestion 
behavior that would lead to a high total exposure. This approach 
reduces the likelihood of not identifying high risks for adverse 
impacts.
    Despite the uncertainties, when individual pollutants or facilities 
do not exceed screening threshold emission rates (i.e., screen out), we 
are confident that the potential for adverse multipathway impacts on 
human health is very low. On the other hand, when individual pollutants 
or facilities do exceed screening threshold emission rates, it does not 
mean that impacts are significant, only that the Agency cannot rule out 
that possibility and that a refined assessment for the site might be 
necessary to obtain a more accurate risk characterization for the 
source category.
    The EPA evaluates the following HAP in the multipathway and/or 
environmental risk screening assessments, where applicable: Arsenic, 
cadmium, dioxins/furans, lead, mercury (both inorganic and methyl 
mercury), POM, HCl, and HF. These HAP represent pollutants that can 
cause adverse impacts either through direct exposure to HAP in the air 
or through exposure to HAP that are deposited from the air onto soils 
and surface waters and then through the environment into the food web. 
These HAP represent those HAP for which the Agency can conduct a 
meaningful multipathway or environmental screening risk assessment. For 
other HAP not included in our screening assessments, the model has not 
been parameterized such that it can be used for that purpose. In some 
cases, depending on the HAP, the Agency may not have appropriate 
multipathway models that allow us to predict the concentration of that 
pollutant. The EPA acknowledges that other HAP beyond these that we are 
evaluating may have the potential to cause adverse effects and, 
therefore, the EPA may evaluate other relevant HAP in the future, as 
modeling science and resources allow.

IV. Analytical Results and Proposed Decisions

A. What actions are we taking pursuant to CAA sections 112(d)(2) and 
112(d)(3)?

    In this proposal, the EPA is proposing the following standards 
pursuant to CAA section 112(d)(2) and (3) for the major source NESHAP 
(40 CFR part 63, subpart QQQ):
     PM limits for anode refining point sources at existing and 
new sources.
     PM limits for process fugitive emissions from rooflines of 
smelting furnaces at existing and new sources.
     PM limits for process fugitive emissions from converters 
at existing and new sources.
     PM limits for process fugitive emissions from roof vents 
at anode refining operations at existing and new sources.
     Mercury limits for any existing and new combination of 
stacks or other vents from the copper concentrate dryers, converting 
department, the anode refining department, and the smelting vessels 
affected sources.
     PM limits for new converters.
    The results and proposed decisions based on the analyses performed 
pursuant to CAA section 112(d)(2) and (3) are presented below. When 
addressing previously unregulated HAP emission sources or unregulated 
HAP from previously regulated sources in the proposed rule, we apply 
the MACT methodology, as described in section II.A above.
1. Anode Refining Point Source Emissions
    The 1998 proposal for primary copper smelting identified anode 
refining in the definition of primary copper smelters. However, at that 
time, the EPA said there were insufficient data to set an emission 
limit for anode refining. Therefore, the Agency did not propose 
specific emission standards for anode copper refining operations in the 
major source NESHAP at that time. In contrast, the 2007 area source 
NESHAP for primary copper smelting (subpart EEEEEE) does include 
emissions standards for anode refining. We conclude that anode refining 
is part of the source category and emits HAP emissions. Therefore, 
pursuant to CAA section 112(d)(2) and (3), the Agency is proposing to 
revise the 2002 major source NESHAP to include emission limits for new 
and existing anode refining point sources. We have anode refining point 
source test data from only one source, and because there are less than 
30 sources in the category, the MACT floor is based on the average 
performance of the best 5 sources (in this case, the upper predictive 
limit (UPL) for the best single source because the Agency only has test 
data from one source). Using available test data, we are proposing a 
MACT floor PM limit as a surrogate for particulate metal HAP, which 
includes, but is not limited to,

[[Page 1633]]

antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, 
manganese, nickel, and selenium compounds. This approach is consistent 
with the approach used to limit metal HAP emissions from the other 
copper smelting processes. A detailed analysis and documentation of the 
MACT floor calculations can be found in the technical document, Draft 
MACT Floor Analyses for the Primary Copper Smelting Source Category. 
The MACT floor emissions limit was calculated based on the average of 
the emissions tests, accounting for variability using the 99 percent 
UPL. The MACT floor limit for the anode refining point source emissions 
for existing and new sources is 5.8 milligrams per dry standard cubic 
meter (mg/dscm).
    We identified one BTF option to further reduce PM emissions from 
anode refining furnaces point sources. The BTF option would require the 
two facilities to each install and operate a wet electrostatic 
precipitator (ESP) in addition to their existing controls (baghouses). 
We estimated that emissions of lead would be reduced by about 0.8 tpy 
and arsenic emissions would be reduced by about 0.3 tpy. For the 2 
existing facilities to comply with this BTF standard, we estimated 
capital costs of $72 million and annualized costs of $9.6 million for a 
cost effectiveness of $8.7 million per ton of HAP metal reduced. 
Regarding new sources, the MACT floor control technology would be a 
baghouse since the current best performing source is controlled with a 
baghouse, and the BTF control option for new sources would also be the 
same as existing (i.e., new source BTF option is based on the addition 
of a Wet ESP on top of the baghouse). Therefore, we assume the costs 
for a new source would also be about the same (i.e., $38 million 
capital, with annualized costs of $4.8 million). The Agency cannot 
estimate a precise cost effectiveness number because it would depend on 
unknown factors (such as concentration of HAP metals in the ore and/or 
other input materials used by a new source). Therefore, the Agency 
assumes the cost effectiveness for new sources would be roughly the 
same as for existing sources described above. Based on this analysis, 
the Agency is not proposing this BTF option for existing or new sources 
because of the relatively high costs and poor cost effectiveness.
    Based on the analyses described above, the Agency is proposing to 
revise the 2002 NESHAP to include the following MACT floor-based 
emission limits for anode refining point sources:
     For existing anode refining point sources located at 
primary copper smelting facilities, we are proposing a PM emissions 
limit of 5.8 mg/dscm.
     For new anode refining point sources located at primary 
copper smelting facilities, we are proposing a PM emissions limit of 
5.8 mg/dscm.
    We propose that compliance with the PM emissions limit for anode 
refining will be demonstrated through an initial compliance test 
followed by a compliance test at least once every year.
2. Process Fugitive Roof Vents
    The major source NESHAP currently does not include standards for 
process fugitive emissions from the rooflines of smelting furnaces, 
converters, or anode refining operations, with the exception of an 
opacity limit for converter roof vents that applies during testing. We 
note that some of these rooflines are among the main sources driving 
risks as described in the discussion of the risk results in section 
IV.B. Pursuant to CAA section 112(d)(2) and (3), the EPA is proposing 
to revise the 2002 NESHAP to include emission limits for rooflines for 
smelting furnaces, converters, and anode refining at existing and new 
sources.
    For smelting furnace and converter rooflines, we evaluated the 
potential to establish MACT floor emissions limits for PM, as a 
surrogate for HAP metals, which includes, but is not limited to, 
antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, 
manganese, nickel, and selenium compounds, based on available test 
data. While the Agency only had test data for one of the two facilities 
(i.e., Freeport), the Agency used those data for calculating MACT floor 
PM limits for converters and smelting furnaces using the UPL 
methodology. Establishing PM as a surrogate for HAP metals is 
consistent with the approach used to limit metal HAP emissions from the 
other copper smelting processes in the current NESHAP and for many 
other source categories (i.e., Ferroalloys Production, Integrated Iron 
and Steel Manufacturing, Iron and Steel Foundries). Based on our 
analyses, we calculated a MACT floor emissions limit of 1.7 lbs/hr PM 
for process fugitive emissions for existing and new converter rooflines 
and a MACT floor limit of 4.3 lbs/hr PM for existing and new smelting 
furnaces rooflines.
    The EPA also evaluated BTF PM limits for smelting furnace and 
converter rooflines based on the potential addition of capture and 
control equipment designed to achieve approximately 90 percent 
reduction in process fugitive emissions. With regard to smelting 
furnaces, based on available information, we estimate that 1.2 tpy year 
of HAP metals are emitted from the smelting flash furnace at Asarco. 
Freeport has two smelting furnaces. Freeport already has primary and 
secondary capture systems that capture and control process fugitives, 
resulting in total estimated HAP metal emissions from both furnaces of 
0.626 tpy based on available test data, or about half of the emissions 
from Asarco's furnace. Asarco has primary capture and control and some 
secondary capture and control, but based on available reported emission 
estimates, Asarco emits significantly more HAP metals than Freeport. 
For the BTF option, we evaluated the potential to add enhanced, 
improved capture and control equipment to achieve about 90 percent 
reduction of HAP metal emissions from the Asarco smelting flash furnace 
(i.e., reduce estimated HAP metal emissions from 1.2 tpy to about 0.12 
tpy). To achieve 90 percent reduction of process fugitives from the 
rooflines, the Agency assumes additional secondary capture and/or 
enhanced capture (e.g., hooding, duct work, fans, etc.) would be needed 
for at least one operation (i.e., matte tapping/pouring). We think 
another significant source of fugitives is the material transfer 
operation, which includes movement of a large ladle containing very hot 
liquid matte from the flash furnace tapping/pouring operation by an 
overhead crane to the converters after each tapping/pouring operation. 
To capture these fugitive emissions from the material transfer 
operations, we assume a roof ventilation capture system would be 
needed. We also assume a new baghouse (or other PM collection control 
device) would be needed to handle these additional exhaust gases. 
Another potential source of fugitives is the pouring/tapping of slag, 
but we are assuming 90 percent reduction could be achieved by adding a 
secondary capture and/or enhanced capture system to reduce fugitive 
emissions from at least one operation, such as the matte tapping/
pouring, without adding capture and control equipment to the slag 
operation. Therefore, no costs are estimated for capturing fugitives 
from the slag pouring process.
    Furthermore, to comply with this BTF option for smelting furnaces, 
we estimate Freeport would also need to reduce HAP emissions. If the 
standard was based on total emissions from smelting furnaces, we 
estimate Freeport would need to achieve 80 percent reduction (e.g., 
from 0.626 to 0.12 tpy,

[[Page 1634]]

which is the target level described above for the Asarco smelting 
furnace). To achieve this level of additional reductions of process 
fugitive emissions, we assume Freeport would need to install two roof 
ventilation capture systems, one for each of its two furnaces. Further 
details of this beyond the floor analysis are provided in the technical 
memo Evaluation of Beyond-the-floor and Ample Margin of Safety Control 
Options and Costs for Process Fugitive Emissions from Smelting Furnaces 
and Converters, and for Point Source Emissions from Anode Refining 
Furnaces and for the Combined Emissions Stream Emitted from the 
Freeport Aisle Scrubber, which is available in the docket for this 
action.
    Based on this analysis, the Agency estimates the BTF PM limit of 
0.12 tpy for existing sources would have total capital costs of 
$26,501,600 and annualized costs of $5,443,937 and would achieve about 
1.53 tpy reduction of HAP metals, with cost effectiveness of $3,445,529 
per ton of HAP metal reduction. With regard to new sources (i.e., new 
furnaces), since the MACT Floor limit is based on test data from 
Freeport, the Agency assumes the BTF controls for a new furnace would 
be similar to the BTF controls described above for Freeport (i.e., need 
to install a roof ventilation capture system on top of whatever 
controls they need to meet the MACT Floor level of control for each new 
furnace). Based on costs estimated for Freeport, and applying this to a 
potential new source, the estimated costs for BTF option for a new 
furnace would be $3,700,000 capital and annualized costs of $600,000 
and achieve about 0.25 tpy metal HAP reduction, with cost effectiveness 
of $2,400,000 per ton of HAP. Further information and details regarding 
the MACT floor and BTF analyses are provided in the memorandum titled 
Draft MACT Floor Analyses for the Primary Copper Smelting Source 
Category, and in the costs memo cited above, which are available in the 
docket for this proposed action.
    With regard to converters, Asarco has three converters and Freeport 
has four converters. Asarco already has primary, secondary and tertiary 
capture and controls, and the reported total estimated HAP emissions 
are 0.0000022 tpy. On the other hand, Freeport has primary and 
secondary capture and controls, but no tertiary controls, and the total 
estimated HAP emissions from Freeport converters are 0.115 tpy. 
Therefore, we considered proposing a BTF option for existing converters 
for the source category that would require reductions at Freeport based 
on installation of tertiary controls which would be similar to the 
tertiary capture and controls on the converters at Asarco or the roof 
ventilation capture system described in the BTF analysis above for 
Freeport smelting furnaces. Given that all four converters at Freeport 
are in the same building, we assume that one such system would be 
sufficient to achieve about 80 percent reduction of fugitives. We 
assume Freeport could route these additional emissions to current 
control devices, since they already have two such control systems 
(i.e., scrubbers). Therefore, we are not including an additional 
baghouse for this potential BTF control option. Based on the analysis 
described above, the Agency estimates this potential BTF standard for 
existing converters would have total capital costs of $3,697,200 and 
annualized costs of $599,663, and achieve about 0.09 tpy reduction of 
HAP metals, with cost effectiveness of $6,662,928 per ton of HAP metal 
reduction.
    With regard to potential BTF standards for process fugitive 
emissions from roof vents for new converters, it is difficult to 
determine the appropriate standard because of a number of issues and 
uncertainties. First, based on reported emissions described above, 
Asarco has substantially lower HAP metal emissions as compared to 
Freeport. However, we have no test data for Asarco, so we have low 
confidence in these reported emissions estimates. Second, as described 
above, the current NESHAP prohibits new sources from using batch 
converters. Therefore, we assume any new converter would be a 
continuous converter, and we have no test data or even estimates of 
process fugitive emissions from continuous converter building roof 
vents. Based on this lack of information, we assume the BTF limit and 
associated costs for process fugitives for new sources would be the 
same as the BTF limit and associated costs for existing sources 
described in the paragraph above.
    The EPA also evaluated the potential to establish MACT floor 
limits, or BTF limits, for HAP metals based on establishing additional 
opacity limits in the NESHAP for each affected source. For example, we 
considered proposing opacity limits consistent with the state air 
permits and opacity limits in the Consent Decree (CD) for Asarco as 
potential MACT standards in addition to, or instead of, the MACT floor 
PM limits. The opacity limits are not expected to result in emission 
reductions. Instead, the opacity would be monitored to ensure that the 
process equipment and control devices are operating properly. 
Furthermore, there would be no additional costs associated with 
establishing these opacity limits, since the limits would be consistent 
with what the facilities are already complying with under the state air 
permits or a CD. There is variability in opacity limits in the state 
air permits and CD and uncertainty as to what specific opacity limits 
represent MACT floor and BTF for each of the processes. These opacity 
limits are described in detail in the memorandum titled Opacity 
Standards for Major Primary Copper Smelting Facilities, which is 
available in the docket.
    Based on the above analyses, we are proposing the MACT floor PM 
emissions limits as a surrogate for metal HAP for converter and 
smelting furnace roof vents. The Agency is not proposing the BTF limits 
for converters or smelting furnaces because of the high costs and poor 
cost effectiveness and uncertainties in the estimates of emissions, 
emissions reductions and costs. Furthermore, the Agency is not 
proposing the opacity limits at this time due to variability in opacity 
limits in the state air permits and CD and uncertainty as to what 
specific opacity limits represent MACT floor and BTF for each of the 
processes. Nevertheless, the EPA solicits comments regarding the 
opacity limits, including whether it would be appropriate to establish 
opacity limits (such as the opacity limits in the state air permits and 
CD) in the NESHAP in addition to, or instead of, the numeric PM MACT 
floor emissions limits described above, and, if so, an explanation as 
to how or why these opacity limits reflect MACT floor, or BTF, levels 
of control. The Agency also solicits comments, data and other 
information regarding the MACT Floor analyses and BTF analyses, and our 
proposed determinations described above.
    With regard to process fugitive emissions from anode refining roof 
vents, we estimate that Freeport emits 5.22 tpy of total metal HAP, 
comprised mainly of lead (4.09 tpy) and arsenic (0.622 tpy), and that 
Asarco emits 0.1076 tpy of total metal HAP. To develop a proposed 
standard for this source, we initially calculated a MACT floor 
emissions limit for PM of 15.2 lbs/hr based on available test data and 
application of the UPL methodology. For this standard, PM serves as a 
surrogate for all particulate HAP metals, similar to the other PM 
limits in the NESHAP.
    Subsequently, we evaluated a potential BTF PM emissions limit for 
the anode refining roof vents, which would be set at a level 
approximately 90 percent lower than the MACT floor

[[Page 1635]]

limit. Based on these analyses, which are described in detail in the 
Draft MACT Floor Analyses for the Primary Copper Smelting Source 
Category memorandum, which is available in the docket, the BTF 
emissions limit for PM is 1.6 lbs/hr. Based on available data, to 
comply with this BTF limit, we expect the Freeport facility would need 
to install improved capture systems, including hoods, ductwork, and 
fans, and one additional baghouse to reduce process fugitive emissions 
from anode refining roof vents. We anticipate the improved capture 
systems would need to be applied to four units, including the two anode 
refining furnace pouring operations, the anode casting wheel, and the 
holding vessel. However, the facility might identify other methods or 
approaches to reduce these emissions, such as applying these equipment 
to only a subset of the four units, limiting the input of certain raw 
materials that have relatively high HAP metal content (such as acid 
plant sludge) into the process, and/or converting their holding vessel 
into an enclosed, controlled anode refining furnace. The Agency expects 
that the capture, control and/or other measures the facility adopts to 
reduce metal HAP emissions from roof vents on anode refining buildings 
to meet the BTF limit will also significantly reduce human health risks 
(e.g., due to lead and arsenic emissions) as discussed below in section 
IV.C.2.
    The Agency estimates that total costs for Freeport to comply with 
this BTF PM emissions limit would be capital costs of $5,887,000 and 
annualized costs of $1,558,000, and would achieve about 4.25 tpy 
reduction of lead and arsenic emissions, with cost effectiveness of 
$367,000 per ton of lead and arsenic reduction. Lead and arsenic 
account for more than 90 percent of the HAP metal emissions from the 
roof vents on the anode refining building at Freeport. This cost 
effectiveness estimate is within the range of cost effectiveness values 
that EPA has historically considered acceptable for lead when compared 
to similar prior rulemakings. For example, in the 2012 Secondary Lead 
Smelting RTR, EPA accepted a cost effectiveness up to about $1.3M/ton 
for metal HAP (mainly Pb, based on 2009 dollars). The EPA's 
consideration of the cost effectiveness estimate of $367,000 per ton of 
lead and arsenic (noted above) also reflects fact-specific 
circumstances for addressing lead and arsenic emissions from the 
Primary Copper Smelting source category. For example, in other 
instances when the focus is on controlling other pollutants, such as 
PM, the agency would compare to other cost-effectiveness values. It is 
also important to note that cost effectiveness is but one factor we 
consider in assessing the cost of the emission reduction at issue here. 
See NRDC v. EPA, 749 F.3d 1055, 1060 (D.C. Cir. April 18, 2014) 
(``Section 112 does not command EPA to use a particular form of cost 
analysis.''). We also consider other factors in assessing the cost of 
the emission reduction as part of our BTF analysis, including, but not 
limited to, total capital costs, annual costs and costs compared to 
total revenues (e.g., costs to revenue ratios). As explained in section 
V.D., the estimated total annualized costs for Freeport are about 0.016 
percent of the annual revenue of the facility's ultimate parent company 
in 2019. Furthermore, based on Freeport's existing permit, background 
information in a consent order with the state of Arizona (which are 
available in the docket), and discussions with facility 
representatives, improvements to their anode refining capture and 
control systems are already being considered. Because estimated HAP 
metals emissions from Asarco are much lower, they would not be expected 
to incur additional control costs to meet the BTF limit. However, 
Asarco would have new costs for compliance testing and recordkeeping 
and reporting, as described below. Overall, the EPA concludes that 
these costs are not economically significant and the cost effectiveness 
is within the range accepted in other NESHAP for these types of HAP 
metals (e.g., Secondary Lead RTR Proposed Rule, 76 FR 99, 29032, May 
19, 2011, and the Final rule, 77 FR 3, 556, January 5, 2012).
    The Agency also considered proposing a BTF lead emissions limit in 
addition to, or instead of, the PM limit since lead is the primary HAP 
metal emitted from the anode refining roof vents. For example, the 
Agency considered a possible lead limit of approximately 0.26 lbs/hr as 
a potential BTF MACT limit for anode refining process fugitive 
emissions, which is described in the MACT Floor memo cited above. 
However, there is some uncertainty with this analysis. It was not clear 
how best to apply the EPA's UPL methodology to the available lead 
emissions data to appropriately account for variability and determine a 
lead UPL limit that would reflect the MACT floor level of control, and 
to then subsequently determine what lead limit would represent a 90 
percent reduction from the lead MACT Floor. The EPA expects the costs 
and reductions for such a lead BTF limit would be the same as the costs 
and reductions for the BTF option for PM described in the above 
paragraph. If the Agency was to establish such a lead limit instead of 
a PM limit, it would also serve as a surrogate for all HAP metals, 
similar to the Secondary Lead Smelting NESHAP, which established 
emissions limits for lead that serve as surrogates for all particulate 
HAP metals. Due to the uncertainties with the analysis of lead 
emissions and methodology used to develop the lead UPL limit, the 
Agency is not proposing this lead limit at this time. However, the EPA 
solicits comments regarding this potential lead limit and whether it 
would be appropriate to establish such a lead limit in addition to, or 
instead of, the PM limit, and if so, why?
    Further information and details regarding the derivation of the 
MACT floor and BTF limits are provided in the memorandum titled Draft 
MACT Floor Analyses for the Primary Copper Smelting Source Category. 
Further information and details regarding the cost estimates for 
Freeport to comply with the BTF limits for the anode refining process 
fugitives roof vents are described in the memorandum Development of 
Estimated Costs for Enhanced Capture and Control of Process Fugitive 
Emissions from Anode Refining Operations at Freeport, which is 
available in the docket for this proposed action.
    Based on the analyses described above, the Agency is proposing a 
BTF emissions limit for PM of 1.6 lbs/hr for anode refining process 
fugitive emissions at existing and new sources.
    In summary, based on the analyses described above, the Agency is 
proposing to revise the 2002 NESHAP to include the following emission 
limits for process fugitive HAP metal emissions from roof vents of 
smelting furnaces, converters, and anode refining processes located at 
primary copper smelting facilities, as follows:
     For existing and new converter operations located at 
primary copper smelting facilities, the Agency is proposing a PM 
emissions limit of 1.7 lbs/hr for process fugitive roof vents.
     For existing and new smelting furnaces located at primary 
copper smelting facilities, the Agency is proposing a PM emissions 
limit of 4.3 lbs/hr for process fugitive roof vents.
     For existing and new anode refining operations located at 
primary copper smelting facilities, the Agency is proposing a PM 
emissions limit of 1.6 lbs/hr for process fugitive roof vents.
    The Agency is proposing that compliance with these emissions limits 
for smelting furnaces, converters and

[[Page 1636]]

anode refining will be demonstrated through an initial compliance test 
followed by a compliance test at least once every year. Moreover, 
facilities will need to monitor various control parameters (e.g., fan 
speed, amperage, pressure drops, and/or damper positioning) on a 
continuous basis to ensure the fugitive capture system and controls are 
working properly.
    With regard to testing and recordkeeping costs, the Agency 
estimates Asarco will have total costs of about $95,000 per year for 
all the testing and recordkeeping and reporting to demonstrate 
compliance with these proposed three new standards for the process 
fugitive emissions roof vents for the converters, smelting furnaces and 
anode refining processes. As mentioned above, Freeport will have no new 
testing costs since they already conduct this testing per ADEQ 
requirements.
3. Mercury
    As mentioned above, the 2002 NESHAP does not include emission 
limits for mercury. The source category emits an estimated 55 pounds of 
mercury annually with 45 pounds per year emitted from the Freeport 
facility. Because of the temperatures of exhaust gas streams 
encountered at primary copper smelting operations, much of the mercury 
emitted is in vapor form, not in a particulate form. The vapor form of 
mercury is not captured by the controls used to reduce PM emissions. 
Therefore, the PM limits do not serve as a surrogate for mercury. 
Pursuant to CAA section 112(d)(2) and (3), the Agency is proposing to 
revise the 2002 NESHAP to include emission limits for mercury.
    Initially the Agency calculated MACT floor limits based on test 
data from both of the primary copper smelting facilities. A detailed 
analysis and documentation of the MACT floor calculations can be found 
in the technical document, Draft MACT Floor Analyses for the Primary 
Copper Smelting Source Category, available in the docket.
    The MACT floor emissions limit for existing sources was calculated 
based on the average of all the emissions tests from both facilities, 
accounting for variability using the 99 percent UPL. A MACT floor based 
on the 99 percent UPL for the combined facility-wide limit for existing 
sources is 0.01 lbs/hr. Based on available data, the Agency concludes 
that both facilities would be able to meet the MACT floor limit with no 
additional controls.
    For new sources, the Agency calculated a MACT floor limit of 
0.00097 lbs/hr based on emissions data from the best performing (or 
lowest emitting) facility, which is Asarco.
    We then evaluated and considered a BTF option to further reduce 
emissions of mercury from existing furnaces and converters. Based on 
available test data, the Agency estimates that the acid plant is by far 
the largest source of mercury emissions at Freeport, accounting for 
about 64 percent of the total, with an estimated 29 lbs/yr of mercury 
emissions. The BTF option for existing sources would require the 
Freeport facility to install and operate an activated carbon injection 
(ACI) system and a polishing baghouse on the combined stack emissions 
release point, the acid plant. The Agency estimates the ACI system 
would achieve approximately 90 percent reduction of mercury from the 
acid plant stack (i.e., 26 lbs/yr reduction of mercury). Therefore, the 
BTF emissions limit would be 0.0043 lbs/hr, which reflects a 90 percent 
reduction from the acid plant portion of the UPL MACT floor level of 
0.01 lbs//hr described above.
    The EPA estimates that these controls would achieve 26 pounds of 
mercury reductions per year (i.e., 90 percent reduction of emissions 
from the acid plant), at a capital cost of $1.5 million and annualized 
costs of $714,000 (in 2019 dollars) for a cost effectiveness of $27,500 
per pound of mercury reduced. After considering both the MACT floor and 
BTF options for existing sources, the EPA is proposing the BTF 
facility-wide emissions limit for mercury of 0.0043 lbs/hr for existing 
sources. The EPA is proposing this BTF limit for mercury because 
mercury is a highly toxic, persistent and bioaccumulative HAP and the 
estimated cost effectiveness is within the range of cost effectiveness 
values the EPA has previously considered acceptable for this HAP after 
correcting to dollar year values. For example, in the 2012 Mercury and 
Air Toxics (MATS) final rule, EPA finalized a BTF standard for mercury 
that had cost effectiveness of $22,496 per pound (based on 2007 
dollars), which would be about $27,500 per pound based on 2019 dollars 
(see Regulatory Impact Analysis for the Final Mercury and Air Toxics 
Standards, December 2011, on pages 1-9 and 1-10, available at: https://www.epa.gov/mats/epa-announces-mercury-and-air-toxics-standards-mats-power-plants-technical-information).
    A detailed analysis and documentation of the BTF option for the 
Primary Copper Smelting major source NESHAP and cost calculations can 
be found in the technical document, Estimated Costs for Beyond-the-
floor Controls for Mercury Emissions from Primary Copper Smelting 
Facilities, available in the docket for this action.
    With regard to new sources, as described above, the MACT floor for 
new sources (i.e., 0.00097 lbs/hr) is already significantly lower than 
the BTF limit for existing sources (i.e., 0.0043 lbs/hr). The EPA 
evaluated a potential BTF option to further reduce emissions of mercury 
from new furnaces and converters. This analysis is very similar to that 
described above for existing furnaces and converters, which would 
require the installation and operation of at least one ACI system plus 
a polishing baghouse on a combined emissions stream from the converter 
and furnace. Therefore, the EPA assumes the costs for a beyond the 
floor option for a new source could be the same as shown above for 
Freeport. With regard to numerical emissions limit, if the Agency 
assumes the same percentage reduction from the new source MACT floor 
(i.e., 0.00097 lbs/hr) that the Agency described above for existing 
sources, that would result in a BTF limit for new sources of 0.00042 
lbs/hr.
    However, with regard to reductions, it is impossible to accurately 
estimate potential reductions in mercury from a new source without 
knowing more information regarding a potential new source. For example, 
mercury emissions are highly dependent on the concentration of mercury 
in the ore and mercury concentrations can vary significantly across 
different ore bodies. If the EPA assumes a new source would have 
similar ore as Asarco, which has much lower mercury emissions compared 
to Freeport, the costs for controls could be similar to those estimated 
for Freeport above. However, the emissions reductions would be far 
lower, and therefore the controls would probably not be cost effective. 
If, on the other hand, the ore was similar to Freeport's, it may not be 
feasible for such a facility to achieve a limit of 0.00042 lbs/hr) with 
these types of controls. For example, if such a facility had 
characteristics similar to Freeport, they would likely need to achieve 
far greater reductions than 90 percent from the acid plant to achieve a 
limit of 0.00042 lbs/hr, which would require additional controls beyond 
the ACI system and polishing baghouse described above.
    Given these uncertainties described above, and the fact that the 
new source MACT floor limit (i.e., 0.00097 lbs/hr) is already 
significantly lower than the BTF limit for existing sources of 0.0043 
lbs/hr, the Agency is proposing a MACT floor limit for mercury for new 
sources of 0.00097 lbs/hr. More details are provided in the memorandums 
titled

[[Page 1637]]

Draft MACT Floor Analyses for the Primary Copper Smelting Source 
Category and Estimated Costs for Beyond-the-floor Controls for Mercury 
Emissions from Primary Copper Smelting Facilities, which are available 
in the docket for this action.
    Based on the analysis described above, the Agency is proposing to 
revise the 2002 NESHAP to include the following emission limits for 
mercury:
     For existing primary copper smelting facilities, the 
Agency is proposing a facility-wide BTF emissions limit for mercury of 
0.0043 lbs/hr.
     For new primary copper smelting facilities, the Agency is 
proposing a facility-wide MACT Floor emissions limit for mercury of 
0.00097 lbs/hr.
    The EPA is proposing that compliance with the mercury emissions 
limits for existing sources will be demonstrated through an initial 
compliance test for each of the affected sources (e.g., furnaces, 
converters, anode refining) within 3 years of publication of the final 
rule followed by a compliance test at least once every year. The actual 
number of tests required will depend on the specific configurations of 
the emissions capture and control equipment and number of release 
points at each facility. For affected facilities that commence 
construction or reconstruction after January 11, 2022, owners or 
operators must comply with all requirements of the subpart, including 
all the amendments being proposed, no later than the effective date of 
the final rule or upon startup, whichever is later.
    The EPA solicit comments, information and data regarding the 
proposed standards for mercury, and the relevant technical analyses 
described above, as well as the proposed compliance dates and testing 
requirements.
4. New Source Limits for Converters in the Major Source NESHAP
    The current requirement for new copper converters is that the 
NESHAP prohibits the use of batch copper converters. By default, new 
copper converters covered by the NESHAP would need to be continuous 
converters, or some other unknown non-batch converter technology, but 
the rule does not include an actual standard for new converters. 
Therefore, pursuant to CAA section 112(d)(2) and (3), the Agency is 
proposing to revise the 2002 NESHAP to include emission limits for new 
converters. We note that there are no existing continuous converters in 
the major source category, and, therefore, the Agency is not 
establishing an emissions limit for existing sources. The Agency is 
proposing a PM with a diameter less than 10 micrometers 
(PM10) emissions limit as a surrogate for metal HAP based on 
PM10 test data from the Kennecott facility which is an area 
source subject to 40 CFR part 63, subpart EEEEEE, area source rule. 
Therefore, the limit is based on the performance of the best similar 
source, which is the Kennecott primary copper smelting facility. The 
proposed input-based emissions limit would require the discharge of 
total PM10 to be no greater than 0.031 pounds of 
PM10 per ton of copper concentrate feed charged to the 
smelting vessel. A detailed discussion of the selection of the new 
source limit can be found in the preamble to the proposed rule for 
subpart EEEEEE (71 FR 59307, 59310, October 6, 2006). The calculation 
of the limit of 0.031 lbs of PM10 per ton of copper 
concentrate feed is described in the technical memo titled: Draft MACT 
Floor Analyses for the Primary Copper Smelting Source Category.
    We then evaluated whether there are any potential BTF options to 
further limit PM10 emissions from new converters; however, 
we did not identify any BTF options. Therefore, we are proposing a 
limit of 0.031 pounds of PM10 per ton of copper concentrate 
feed charged to the smelting vessel.
    The EPA proposes that compliance with the PM10 emissions 
limit for new converters would be demonstrated through an initial 
compliance test followed by a compliance test at least once every year.

B. What are the results of the risk assessment and analyses?

1. Chronic Inhalation Risk Assessment Results
    Table 1 of this preamble provides a summary of the results of the 
inhalation risk assessment for the source category. The two facilities 
in this major source category are located in Arizona in a rural, desert 
environment that is, for the most part, sparsely populated. More 
detailed information on the risk assessment can be found in the 
document titled Residual Risk Assessment for the Primary Copper 
Smelting Major Source Category in Support of the Risk and Technology 
Review 2021 Proposed Rule, available in the docket for this rule.

                                Table 1--Primary Copper Smelting Major Source Category Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Maximum individual       Population at         Annual cancer         Maximum noncancer HI and 3-month lead       Maximum screening
                      cancer risk (in 1     increased risk of   incidence (cases per           concentration (ug/m\3\) \3\           acute noncancer HQ
                     million) \2\ based     cancer >= 1-in-1    year) based on . . . ----------------------------------------------  \4\ based on . . .
     Number of            on . . .        million based on . . ----------------------                                              ---------------------
  facilities \1\   ----------------------           .
                                         ----------------------   Actual   Allowable     Actual emissions     Allowable emissions
                      Actual   Allowable    Actual   Allowable  emissions  emissions                                                  Actual emissions
                    emissions  emissions  emissions  emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
2.................         80         90     26,125     29,001      0.003      0.003  HI = 1 (arsenic)       HI = 1 (arsenic)       HQ (REL) = 7
                                                                                       developmental.         developmental.         (Arsenic).
                    .........  .........  .........  .........  .........  .........  Pb Conc: 0.17........  Pb Conc: 0.24 .......
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer and noncancer risk due to arsenic emissions from the source category, 71 percent from the anode refining
  roofline at Freeport and 23 percent from anode furnaces and converters point source emissions from the Aisle Scrubber at Freeport.
\3\ The max 3-month off-site lead concentration is compared to the lead (Pb) NAAQS standard of 0.15 ug/m\3\ based upon actual and allowable emissions
  from the source category. The Pb NAAQS standard was developed to address all exposure pathways (inhalation and ingestion).
\4\ The maximum estimated off-site acute exposure concentration was divided by available short-term dose-response values to develop an array of HQ
  values. HQ values shown use the lowest available acute dose-response value, which in most cases is the REL. There are no other acute health benchmarks
  for arsenic other than the 1-hour REL.

    Results of the inhalation risk assessment based on actual emissions 
indicate that the cancer MIR is 80-in-1 million. The total estimated 
cancer incidence from this source category is 0.003 excess cancer cases 
per year, or one excess case every 333 years, with arsenic compounds 
contributing 95 percent of the cancer incidence for the source 
category. Approximately 26,125 people of the 46,460 people in the model 
domain are estimated to have cancer risks above 1-in-1 million from HAP 
emitted from this source category. The HEM-4 model predicted the 
maximum chronic noncancer HI value for the source category is equal to 
1 (developmental), driven by emissions of

[[Page 1638]]

arsenic from the anode refining roofline at Freeport and the anode 
furnaces and secondary converter point source emissions emitted through 
the Aisle Scrubber at Freeport.
    Results of the inhalation risk assessment based on MACT-allowable 
emissions indicate that the cancer MIR is 90-in-1 million. The total 
estimated cancer incidence from this source category is 0.003 excess 
cancer cases per year, or one excess case every 333 years, with arsenic 
contributing 90 percent and cadmium contributing 8 percent of the 
cancer incidence for the source category. Approximately 29,001 people 
are estimated to have cancer risks above 1-in-1 million from exposure 
to HAP emissions allowed under the NESHAP. The HEM-4 model predicted 
the maximum chronic noncancer HI value for the source category is equal 
to 1 (developmental), driven by emissions of arsenic from the anode 
refining roofline and the anode furnaces and converters. No individuals 
are estimated to have exposures that result in a noncancer HI above 1 
at allowable emission rates.
    A refined modeling analysis was conducted at the facility with the 
highest annual concentration of lead to characterize ambient 
concentrations of lead for 3-month intervals. The maximum 3-month 
concentration was predicted for each off-site receptor. The 
concentrations were then compared to the Lead (Pb) NAAQS of 0.15 ug/
m\3\. The maximum 3-month off-site modeled concentration was 0.17 ug/
m\3\ for actual emissions and 0.24 ug/m\3\ for allowable emissions, and 
these results occurred near the Freeport facility. The lead standard is 
based on exposure to all pathways (inhalation and ingestion) due to 
lead emitted to the air and includes an adequate margin of safety to be 
protective of all sub-populations at risk, especially children. Lead 
concentrations above the standard increase the risk of developmental 
effects for children. Model results indicate that, based on actual 
emissions, a single census block (about five people) has the potential 
to be exposed to lead concentrations greater than the lead NAAQS. For 
allowable emissions, the analysis predicts that eight census blocks 
(about 50 people) have modeled lead concentrations greater than the 
lead NAAQS. While the EPA examines the potential for lead risks and 
exposure by comparing ambient levels directly to the NAAQS, the 
noncancer risks predicted for this category from arsenic are also 
associated with developmental effects. Thus, while the Agency did not 
combine the risk of developmental effects from exposure to lead with 
the hazard associated with exposure to arsenic, the Agency would expect 
their combined hazard to be greater than each of the individual 
exposures and hazards presented above.
2. Screening Level Acute Risk Assessment Results
    To better characterize the potential health risks associated with 
estimated worst-case acute exposures to HAP, and in response to a key 
recommendation from the SAB's peer review of the EPA's RTR risk 
assessment methodologies, the Agency examined a wider range of 
available acute health metrics than the Agency does for our chronic 
risk assessments. This is in acknowledgement that there are generally 
more data gaps and uncertainties in acute reference values than there 
are in chronic reference values. By definition, the acute REL 
represents a health-protective level of exposure, with effects not 
anticipated below those levels, even for repeated exposures. However, 
the level of exposure that would cause health effects is not 
specifically known. Therefore, when an REL is exceeded and an AEGL-1 or 
ERPG-1 level is available (i.e., levels at which mild, reversible 
effects are anticipated in the general public for a single exposure), 
the Agency typically uses them as an additional comparative measure, as 
they provide an upper bound for exposure levels above which exposed 
individuals could experience effects. As the exposure concentration 
increases above the acute REL, the potential for effects increases.
    A review of all modeled off-site receptors for the Primary Copper 
Smelting source category identified exceedance of the 1-hour REL for 
arsenic, resulting in an HQ of 7 for arsenic. This is for actual 
baseline emissions. Satellite imagery for this location identifies it 
as a residential location approximately 4,200 meters northeast of the 
Freeport facility. It is also important to note that the primary source 
of the arsenic emissions from the anode furnace/converter and anode 
refining roofline was modeled with an hourly emissions multiplier of 3 
times the annual average emissions rate. There are no AEGL or ERPG 
levels available for arsenic. No other HAP exposure concentrations 
exceeded acute benchmarks. Further details on the acute HQ estimates 
are provided in Appendix 10 of the risk report for this source 
category.
3. Multipathway Risk Screening
    For this source category both facilities reported emissions of 
lead, which are compared to the lead NAAQS, and emissions of PB-HAP, 
which are compared to the Tier 1 screening threshold emission rate for 
each PB-HAP based upon a combined fisher/farmer scenario with upper-
bound ingestion rates. The two facilities within this source category 
both reported emissions of carcinogenic PB-HAP (arsenic) and emissions 
of non-carcinogenic PB-HAP (cadmium and mercury) that exceeded their 
respective Tier 1 screening threshold emission rates. For facilities 
that exceed the Tier 1 multipathway screening threshold emission rate 
for one or more PB-HAP, we use additional facility site-specific 
information to perform a Tier 2 multipathway screening assessment. For 
the Tier 2 screening, the farmer and fisher scenarios are not combined 
as they are in the Tier 1 screening. Instead, the farmer and fisher 
scenarios are treated as separate individuals with the fisher scenario 
based upon modeled impacts to local lakes within 50 kilometers of the 
facility. Further details on the tiered multipathway screening 
methodology can be found in Appendix 6 of the Residual Risk Assessment 
for the Primary Copper Smelting Major Source Category in Support of the 
Risk and Technology Review 2021 Proposed Rule.
    For arsenic, both facilities had Tier 2 SVs (cancer) greater than 
1, with a maximum SV of 3,000 for the farmer scenario, a maximum SV of 
1,000 for the rural gardener scenario, and a maximum SV of 100 for the 
fisher scenario. For cadmium, the Tier 2 screening assessment for both 
the farmer and gardener (rural) scenarios resulted in maximum Tier 2 
SVs (noncancer) of 4. For the fisher scenario, Tier 2 noncancer SVs 
were greater than 1 for mercury compounds and cadmium compounds for one 
facility with a maximum noncancer SV of 20 for mercury and the maximum 
noncancer SV of 10 for cadmium.
    Based upon these results, a Tier 3 screening assessment was 
conducted for both the fisher and gardener (rural) scenarios. A Tier 3 
screening analysis was performed for arsenic, cadmium, and mercury 
emissions. In the Tier 3 screen for the fisher scenario, lakes near the 
facilities were reviewed on aerial photographs. As a result of this 
assessment, the features that were initially identified as lakes 
driving the Tier 2 screening risks for the fisher scenario were found 
to be tailings basins (not lakes), which are not fishable. After the 
tailings basins were removed from the fisher scenario analysis, the 
maximum cancer SV for arsenic emissions was 30, the maximum noncancer 
SV for mercury emissions

[[Page 1639]]

was 4, and the maximum noncancer SV for cadmium emissions was 4.
    The Tier 3 gardener (rural) scenario was refined with the placement 
of the garden at the MIR residential receptor location approximately 4 
km northeast of the facility versus the worst-case near-field location. 
Based on these Tier 3 refinements to the gardener scenario, the maximum 
Tier 3 cancer SV of 1,000 (rounded to 1 significant figure) remained 
the same for arsenic emissions, while the maximum noncancer SV 
decreased from 4 to 3 for cadmium emissions. An exceedance of a 
screening threshold emission rate or SV in any of the tiers cannot be 
equated with a risk value or an HQ (or HI). Rather, it represents a 
high-end estimate of what the risk or hazard may be. For example, an SV 
of 2 for a non-carcinogen can be interpreted to mean that the Agency is 
confident that the HQ would be lower than 2. Similarly, a Tier 2 cancer 
SV of 7 means that we are confident that the cancer risk is lower than 
7-in-1 million. Our confidence comes from the conservative, or health-
protective, assumptions encompassed in the screening tiers: The Agency 
chooses inputs from the upper end of the range of possible values for 
the influential parameters used in the screening tiers, and the Agency 
assumes that the exposed individual exhibits ingestion behavior that 
would lead to a high total exposure.
    The EPA determined that it is not necessary to go beyond the Tier 3 
lake and gardener analysis or conduct a site-specific assessment for 
arsenic, cadmium, and mercury. The EPA compared the Tier 2 screening 
results to site-specific risk estimates for five previously assessed 
source categories. These are the five source categories, assessed over 
the past 4 years, which had characteristics that make them most useful 
for interpreting the Primary Copper Smelting screening results. For 
these source categories, the EPA assessed fisher and/or gardener risks 
for arsenic, cadmium, and/or mercury by conducting site-specific 
assessments. The EPA used AERMOD for air dispersion and Tier 2 screens 
that used multi-facility aggregation of chemical loading to lakes where 
appropriate. These assessments indicated that cancer and noncancer 
site-specific risk values were at least 50 times lower than the 
respective Tier 2 screening values for the assessed facilities, with 
the exception of noncancer risks for cadmium for the gardener scenario, 
where the reduction was at least 10 times (refer to EPA Docket ID: EPA-
HQ-OAR-2017-0015 and EPA-HQ-OAR-2019-0373 for a copy of these 
reports).\30\
---------------------------------------------------------------------------

    \30\ EPA Docket records (EPA-HQ-OAR-2017-0015): Appendix 11 of 
the Residual Risk Assessment for the Taconite Manufacturing Source 
Category in Support of the Risk and Technology Review 2019 Proposed 
Rule; Appendix 11 of the Residual Risk Assessment for the Integrated 
Iron and Steel Source Category in Support of the Risk and Technology 
Review 2019 Proposed Rule; Appendix 11 of the Residual Risk 
Assessment for the Portland Cement Manufacturing Source Category in 
Support of the 2018 Risk and Technology Review Final Rule; Appendix 
11 of the Residual Risk Assessment for the Coal and Oil-Fired EGU 
Source Category in Support of the 2018 Risk and Technology Review 
Proposed Rule; and EPA Docket: (EPA-HQ-OAR-2019-0373): Appendix 11 
of the Residual Risk Assessment for Iron and Steel Foundries Source 
Category in Support of the 2019 Risk and Technology Review Proposed 
Rule.
---------------------------------------------------------------------------

    Based on our review of these analyses, if the Agency was to perform 
a site-specific assessment for the Primary Copper Smelting Source 
Category, the Agency would expect similar magnitudes of decreases from 
the Tier 2 SVs. As such, based upon the conservative nature of the 
screens and the level of additional refinements that would go into a 
site-specific multipathway assessment, were one to be conducted, we are 
confident that the HQ for ingestion exposure, specifically cadmium and 
mercury through fish ingestion, is less than 1. For arsenic, maximum 
cancer risk posed by fish ingestion would also be reduced to levels 
below 1-in-1 million, and maximum cancer risk under the rural gardener 
scenario would decrease to 20-in-1 million or less. Also, based upon 
the arid climate of the area and the hypothetical nature/location of 
the garden, estimated risks from this scenario seem unlikely. Further 
details on the Tier 3 screening assessment can be found in Appendix 10-
11 of Residual Risk Assessment for the Primary Copper Smelting Major 
Source Category in Support of the Risk and Technology Review 2021 
Proposed Rule.
    In evaluating the potential for adverse health effects from 
emissions of lead, the EPA compared modeled maximum 3-month lead 
concentrations to the secondary NAAQS level for lead of (0.15 [mu]g/
m\3\) over a 2-year period. The highest off-site 3-month average lead 
concentration based upon actual emissions was 0.17 [mu]g/m\3\. The 
highest concentration based on allowable emissions was 0.24 [mu]g/m\3\. 
Both results are above the lead NAAQS standard, indicating a potential 
for adverse health effects from multipathway exposure to lead. For 
further information on the modeling and monitoring analysis for lead 
refer to section IV.B.1 (Chronic Inhalation Risk Assessment Results) 
and section IV.B.6 (Monitor to Model Analysis for Arsenic and Lead).
4. Environmental Risk Screening Results
    As described in section III.A of this document, the Agency 
conducted an environmental risk screening assessment for the primary 
copper source category for the following pollutants: Arsenic, cadmium, 
and mercury. In the Tier 1 screening analysis for PB-HAP (other than 
lead, which was evaluated differently), arsenic, cadmium, divalent 
mercury and methyl mercury exceeded at least one ecological benchmark, 
requiring a Tier 2 screen.
    A Tier 2 screening assessment was performed for arsenic, cadmium, 
divalent mercury and methyl mercury. Arsenic, divalent mercury, and 
methyl mercury had no Tier 2 exceedances for any ecological benchmark. 
Two facilities contributing emissions to the same lake had cadmium 
emissions that resulted in Tier 2 exceedances for fish no-observed-
adverse-effect level (avian piscivores), fish geometric-maximum-
allowable-toxicant level (avian piscivores), and fish lowest-observed-
adverse-effect level (avian piscivores) benchmarks with a maximum SV of 
3.\31\
---------------------------------------------------------------------------

    \31\ The two facilities in the multipathway analysis are within 
the same model domain and contribute cadmium emissions to a common 
lake with the Freeport facility contributing >99 percent of the 
cadmium loading to the target lake (USGS ID:26665).
---------------------------------------------------------------------------

    A Tier 3 screening analysis was performed for cadmium emissions. In 
the Tier 3 screen, lakes near the facilities were reviewed on aerial 
photographs. As a result of this assessment, the waterbody that was 
initially identified as a lake that was driving the Tier 2 
environmental screening risks for cadmium was found to be a tailings 
basin and was removed from the analysis. After environmental impacts 
that had been estimated for the tailings basin were removed from the 
analysis, there were no exceedances of cadmium environmental screening 
benchmarks in Tier 3. For lead, the Agency estimated an exceedance of 
the secondary lead NAAQS at one census block at a lead concentration of 
0.17 ug/m\3\. The exceeded census block constitutes less than 0.1 
percent of the modeled area around the facility. Therefore, based on 
the limited extent of the lead exceedance and the other results of the 
environmental risk screening analysis, the Agency does not expect an 
adverse environmental effect as a result of HAP emissions from this 
source category.

[[Page 1640]]

5. Facility-Wide Risk Results
    The source category includes all the emissions at the facility. 
Thus, the facility-wide risk is the same as the risk posed by the 
actual emissions from the source category, refer to Table 1, with no 
change in incidence or risk drivers.
6. Monitor To Model Analysis for Arsenic and Lead
    A monitor to model comparison analysis was conducted for the 
monitors located at both primary copper smelting facilities to 
characterize the effectiveness of the emissions modeling and for 
purposes of risk characterization. Monitoring data collected from both 
sites represent current process operations at the facilities including 
process fugitives as well as background contributions from historic 
activity such as road dust and re-entrainment. A review of emission 
inventories for the area indicates both plants are the primary 
contributor of arsenic and lead emissions for their locations. 
Monitoring samples are collected on a one in 6-day schedule for a 24-
hour continuous period. This schedule and the number of active source-
driven monitors provide an indication of what emission sources may be 
contributing to the monitor but still do not provide enough temporal 
resolution to apportion the emissions to a specific source. Because the 
sample is collected over a 24-hour period, this apportionment is 
further complicated by factors such as varying surface winds (wind 
speed and wind direction) that occur throughout the day as well as 
unexpected changes in production or upset events that may occur at the 
plant.
    The Hayden area of Gila and Pinal Counties in Arizona is currently 
classified as nonattainment for the 2010, 1-hour primary SO2 
NAAQS; 2008 lead NAAQS; and 1987 PM10 NAAQS. Asarco is the 
only source of lead and SO2 emissions in the Hayden 
nonattainment area. Emission reductions required under a CD with the 
EPA were designed to bring the Asarco facility into compliance with the 
NESHAP by December 2018. In addition, revisions to the state 
implementation plan (SIP) were intended to provide for attainment with 
the SO2 and lead NAAQS by the attainment dates of October 
2018 and October 2019, respectively. A review of 2019 monitoring data 
from four total suspended particulates (TSP) lead monitors and five 
particulate (PM10) monitors in the area around Asarco that 
measure arsenic and other metals were compared to model results. The 
modeled concentrations predicted in the above analysis for Asarco were 
two to five times lower than the monitor concentrations. Refer to Table 
2 for comparisons and the respective ambient air concentrations and 
risk values. Monitor 23 (4th Street and Hillcrest Avenue) was 
identified as the critical monitor due to its close proximity (within 
100 meters) of the modeled MIR location for Asarco. Based upon the 2019 
arsenic monitoring data from Monitor 23, excess cancer risks were equal 
to 90-in-1 million compared to a model-predicted monitor value of 50-
in-1 million for Asarco. Monitor values also indicate a chronic 
noncancer HQ of 1 from arsenic.
    The Miami area of Gila County, Arizona, was classified as 
nonattainment for the 2010, 1-hour primary SO2 NAAQS in 
August 2013. Freeport is the only source of lead and SO2 
emissions in the Miami nonattainment area. Emission reductions required 
under a revision to the SIP were designed to provide for attainment of 
the SO2 NAAQS by October 2018. The 2019 monitoring data from 
the lead NAAQS (TSP) monitor were compared to model results, with 
modeled concentrations being in close agreement to monitored 
concentrations. Refer to Table 2 for comparisons of the annual 
monitored concentrations. AQS Monitor (04-007-8000) is located at the 
Miami golf course (SR 188 and US 60) and is the only operating monitor 
for the area. This monitor is located approximately 1,400 meters 
southwest of the MIR location from the HEM-4 model run. Based on the 
model analysis presented above, the monitor is located such that the 
maximum off-site modeled lead concentration may be up to a factor of 
four times higher than measured at the golf course site. Thus, based on 
the modeling analysis presented in this risk assessment, the predicted 
off-site ambient concentrations near the Freeport facility may approach 
or exceed the maximum lead 3-month average NAAQS of 0.15 ug/m\3\.

                          Table 2--Monitor to Model Comparison for Primary Copper Smelting Source Category for Arsenic and Lead
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                          Annual average conc. (ug/m\3\)   Cancer risk (xx-in-1 million)                HQ
                          Site                           -----------------------------------------------------------------------------------------------
                                                               Model          Monitor          Model          Monitor          Model          Monitor
--------------------------------------------------------------------------------------------------------------------------------------------------------
Asarco Monitor 23 (As) \1\ \2\..........................           0.011           0.022              50              90             0.8             1.4
Asarco Monitor 23 (Pb) \1\ \2\..........................           0.025           0.098              NA              NA              NA              NA
Freeport NAAQS Monitor (Pb) \2\.........................           0.026           0.022              NA              NA              NA              NA
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The Asarco Monitor 23 is located off-site and within 100 meters of the modeled MIR residential location.
\2\ The monitor and modeling data were based upon emission estimates and monitoring data collected for the 2019 calendar year.

    With regard to emissions estimates used for the modeling analysis, 
as discussed in section II.C above, the Agency has higher confidence 
and less uncertainty with the Freeport emissions as compared to Asarco 
because the Agency has multiple test results for both point and non-
point (i.e., fugitive) sources of emissions for Freeport. However, for 
Asarco, the Agency only has test data for the point source emissions. 
The EPA has no test data for the non-point emissions. For Asarco, the 
non-point (fugitive) emissions estimates are based on emission factors 
and various calculations.
7. How is baseline risk distributed across demographic groups?
    To examine the potential for any environmental justice issues that 
might be associated with the source category, EPA performed a baseline 
demographic analysis to identify how risk is distributed among 
different demographic groups of the populations living within 5 km and 
within 50 km of the two major source facilities. The methodology and 
the results of the baseline demographic analysis are presented in the 
technical report, Risk and Technology Review--Analysis of Demographic 
Factors for Populations Living Near Primary Copper Smelting Source 
Category Operations, which is available in the docket. This report is 
discussed in this section regarding estimated impacts under the 
existing standards (i.e., baseline). In the analysis,

[[Page 1641]]

we evaluated the distribution of HAP-related cancer and noncancer risks 
from the primary copper smelting major source category across different 
demographic groups within the populations living near facilities.\32\ 
With regard to the Kennecott area source facility, we note that 
Kennecott is located in a very remote area. The closest residence is 
estimated to be at least 3 miles from the smelting facility. 
Furthermore, as described in section III.C of this preamble, ambient 
monitoring for lead was conducted for about 7 years in the vicinity of 
Kennecott by Utah DAQ which demonstrated that the likelihood of 
violating the NAAQS for lead was so low, it would no longer be 
necessary to run the monitor. Therefore, we did not conduct a 
demographic analysis for Kennecott.
---------------------------------------------------------------------------

    \32\ Demographic groups included in the analysis are: White, 
African American, Native American, other races and multiracial, 
Hispanic or Latino, children 17 years of age and under, adults 18 to 
64 years of age, adults 65 years of age and over, adults without a 
high school diploma, people living below the poverty level, people 
living two times the poverty level, and linguistically isolated 
people.
---------------------------------------------------------------------------

    The results of the baseline demographic analyses, which reflect an 
average for the two major sources, are summarized in Table 3 below. 
These results, for various demographic groups, are based on the 
estimated risk from actual emissions levels for the population living 
within 50 km of the facilities.

  Table 3--Primary Copper Smelting Source Category Baseline Demographic
                          Risk Analysis Results
------------------------------------------------------------------------
                                                        Population with
                                                       cancer risk at or
                                                          above 1-in-1
                                       Nationwide \1\    million due to
                                                         primary copper
                                                          smelting \2\
------------------------------------------------------------------------
Total Population.....................     328,016,242             26,125
------------------------------------------------------------------------
                      White and Minority by Percent
------------------------------------------------------------------------
White \3\............................              60                 36
All Other Races......................              40                 64
------------------------------------------------------------------------
                           Minority by Percent
------------------------------------------------------------------------
African American.....................              12                0.7
Native American......................             0.7                 27
Hispanic or Latino (includes white                 19                 33
 and nonwhite).......................
Other and Multiracial................               8                  3
------------------------------------------------------------------------
                            Income by Percent
------------------------------------------------------------------------
Below Poverty Level..................              13                 27
Above Poverty Level..................              87                 73
------------------------------------------------------------------------
                          Education by Percent
------------------------------------------------------------------------
Over 25 and without High School                    12                 20
 Diploma.............................
Over 25 and with a High School                     88                 80
 Diploma.............................
------------------------------------------------------------------------
                   Linguistically Isolated by Percent
------------------------------------------------------------------------
Linguistically Isolated..............               5                  3
------------------------------------------------------------------------
\1\ The nationwide population is based on the Census' 2015-2019 American
  Community Survey five-year average and includes Puerto Rico.
\2\ Demographics within HEM4 model domain (50 km) of facilities in
  source category.
\3\ We use the term White throughout as shorthand to refer to what
  Census calls White alone (i.e., single race) who are not Hispanic or
  Latino (i.e., NHWA). Minority is used throughout to refer to the rest
  of the population (i.e., all but NHWA). Minority is made up of four
  groups: African American is used here to refer to what Census calls
  ``Black or African American alone,'' Native American here refers to
  what Census calls ``American Indian and Alaska Native alone,''
  Hispanic or Latino is the term as used by Census, and Other and
  Multiracial here refers to the remainder of the minority population.

    The results of the primary copper smelting source category baseline 
demographic analysis indicate that emissions from the major source 
category expose approximately 26,125 people to a cancer risk at or 
above 1-in-1 million. No person is exposed to a chronic noncancer TOSHI 
greater than 1. As shown in Table 3, the average percentages of the at-
risk population in the Native American, Hispanic, Below Poverty Level, 
and Over 25 without High School Diploma demographic groups are 
significantly greater than their respective nationwide percentages. 
Note, for one facility, Asarco, the baseline demographic analysis 
indicates that of the population with risks at or above 1-in-1 million, 
73 percent are Hispanic, which is significantly greater than the 
nationwide percentage, 19 percent, as described further in the 
demographic analysis technical report cited above. Thus, the elevated 
cancer risks associated with emissions from the major source category 
disproportionately affect communities with environmental justice 
concerns, including low-income residents, Native Americans, and 
Hispanics living near these facilities.
    With regard to acute noncancer risks, the acute screening analysis 
completed for this proposed rule is a conservative approach that 
applies health protective assumptions that every process releases its 
peak hourly emissions at the same hour, that the reasonable worst-case 
dispersion conditions occur at that same

[[Page 1642]]

hour, and that an individual is present at the location of maximum HAP 
concentration for that hour. Estimating population risks or the number 
of individuals exposed to acute events that exceed the arsenic acute 1-
hour REL would be problematic due to the nature of the screening 
assessment, especially for a specific hour in which this event would 
occur. Due to this uncertainty, we did not complete a demographics 
analysis for acute noncancer risks.
    With regard to lead, the modeled exceedances of the lead NAAQS 
based on estimated actual emissions were estimated to occur only in a 
small area near Freeport and we did not have precise demographic 
information for that specific area. Therefore, we did not conduct a 
demographics analysis for lead.
    Nevertheless, since the potential acute risks from arsenic 
emissions, and the highest estimated exposures due to lead emissions, 
are from the same facility and sources that drive the cancer risks for 
the source category, we expect that the demographic make-up of the 
exposed populations living near the facility (who could have potential 
acute risks and higher lead exposures due to these emissions) would be 
similar to the profiles presented in Table 3 above.

C. What are our proposed decisions regarding risk acceptability, ample 
margin of safety, and adverse environmental effect?

1. Risk Acceptability
    As explained in section III of this preamble, the EPA sets 
standards under CAA section 112(f)(2) using ``a two-step standard-
setting approach, with an analytical first step to determine an 
`acceptable risk' that considers all health information, including risk 
estimation uncertainty, and includes a presumptive limit on maximum 
individual risk (MIR) of approximately 1-in-10 thousand'' (see 54 FR 
38045, September 14, 1989). In this proposal, the EPA estimated risks 
based on actual and allowable emissions from the primary copper 
smelting major source category under the current NESHAP.
    The estimated inhalation cancer risk to the individual most exposed 
to allowable emissions from the source category is 90-in-1 million. The 
estimated inhalation cancer risk to the individual most exposed to 
actual emissions from the source category is 80-in-1 million. The 
estimated incidence of cancer due to inhalation exposures is 0.003 
excess cancer cases per year, or one excess case every 333 years. The 
estimated number of people to have cancer risk above 1-in-1 million 
from HAP allowed to be emitted from the facilities in this source 
category is 29,001.
    Based on allowable lead emissions, the maximum 3-month off-site 
modeled concentration was estimated to be as high as 0.24 ug/m\3\, 
above the lead NAAQS of 0.15 ug/m\3\. Further, based on actual lead 
emissions, the maximum 3-month off-site modeled concentration was 
estimated to be 0.17 ug/m\3\, above the lead NAAQS of 0.15 ug/m\3\. The 
lead standard is based upon exposure through all pathways (inhalation 
and ingestion) with an adequate margin of safety to be protective of 
all sub-populations at risk, including and especially children. Lead 
concentrations above the NAAQS increase the risk of developmental 
effects for children. While the Agency examined the potential risk from 
lead exposure by comparing ambient levels directly to the NAAQS, the 
noncancer risks predicted for this category from arsenic are also 
associated with developmental effects. Thus, while the Agency did not 
combine the risk of developmental effects from exposure to lead with 
the hazard index associated with exposure to arsenic, the Agency would 
expect the combined exposures and hazards to be greater than each of 
the individual exposures and hazards presented above.
    The multipathway risk assessment results indicated a maximum Tier 3 
cancer risk of 1000-in-1 million based on the rural gardener scenario 
and a maximum Tier 3 noncancer HQ of 4 for the fisher scenario. Based 
upon past experience with site-specific assessments, the Agency would 
expect a minimum decrease by a factor of 50 for the above risks. Also, 
due to the arid climate of the area and the hypothetical nature/
location of the garden, estimated upper-end ingestion rates for this 
scenario seem unlikely for this area. Further, the Agency estimated 
that the HQs for ingestion exposure, specifically for cadmium and 
mercury through fish ingestion, are less than 1.
    The acute risk screening assessment of reasonable worst-case 
inhalation impacts indicates a maximum off-site acute HQ (REL) of 7, 
located at a residential location.
    Considering all of the health risk information and factors 
discussed above, including the uncertainties discussed in section III 
of this preamble, the EPA proposes that the risks for this source 
category under the current MACT provisions are unacceptable. This 
proposed determination is largely based on the estimated exceedances of 
the lead NAAQS described above along with the maximum acute HQ of 7 for 
arsenic, which indicate there are significant risks of noncancer health 
effects for people near the facility. Also contributing to this 
proposed determination, although to a lesser extent, are the inhalation 
cancer MIRs due to arsenic, with an estimated MIR of 80-in-1 million 
for actual emissions and 90-in-1 million for allowable emissions, which 
are approaching the presumptive level of unacceptability of 100-in-1 
million (described above in this preamble).
2. Proposed Controls To Address Unacceptable Risk
    As discussed in section IV.C.1 above, the Agency is proposing that 
baseline risks (actual emissions) are unacceptable. The largest 
contributors to these unacceptable risks are the metal HAP (mainly lead 
and arsenic) emissions from the anode refining process fugitive 
emissions roof vents at Freeport, which constitute about 71 percent of 
the MIR. As described in section IV.A above, under the section 
112(d)(2)/(d)(3) of the CAA, the Agency is proposing BTF emissions 
limits for PM, as a surrogate for metal HAP, for the anode refining 
process fugitive emissions roof vents, which the Agency estimates will 
reduce HAP metal emissions from this source by about 90 percent at 
Freeport. The EPA evaluated whether these reductions will further 
reduce cancer risks and noncancer hazards to an acceptable level by 
conducting a ``post-control'' risk assessment to estimate what the 
risks will be after implementation of the BTF PM emissions limit. Based 
on that analysis, the Agency estimates the inhalation cancer MIR will 
be reduced from 80-in-1 million to 30-in-1 million at Freeport with 
20,566 people exposed to a cancer risk greater than or equal to 1-in-1 
million, a 21 percent reduction when compared to cancer risk from 
actual emissions. The chronic noncancer HI will remain well below 1 and 
the maximum off-site acute HQ based on the 1-hour REL will be reduced 
from 7 to 2. Further, the maximum 3-month lead ambient concentration 
will be reduced below the NAAQS from 0.17 [mu]g/m\3\ to 0.073 ug/m\3\. 
However, the modeled cancer MIR for the source category would be 60-in-
1 million, since the EPA expects the BTF limit will achieve no 
reductions from Asarco. Based on these results, the Agency is proposing 
that the emissions reductions that will be achieved by the BTF 
emissions limit for PM for anode refining process fugitive roof vents 
(described in section IV.A above) will be sufficient to achieve 
acceptable risks.
    Therefore, to reduce risks to a level that would be considered 
acceptable,

[[Page 1643]]

under section 112(f) of the CAA, the Agency is proposing the exact same 
emissions limit for anode refining roof vents that the Agency is 
proposing as a BTF limit for the roof vents in buildings housing anode 
refining under CAA section 112(d)(2) and (d)(3) (which is described in 
more detail above in section IV.A.2). This is expected to require 
additional capture and control systems to reduce process fugitive 
emissions at the Freeport facility. The estimated emissions at Asarco 
are considerably lower than at Freeport. Asarco is not expected to have 
to install additional capture and control systems to comply with the 
proposed limits for anode refining roof vents, although they would 
incur costs for emissions testing. For anode refining roof vents, under 
section 112(f)(2) of the CAA, the Agency is proposing the following 
risk-based emission limits:
     For existing and new anode refining operations located at 
primary copper smelting facilities, the Agency is proposing an 
emissions limit for PM of 1.6 lbs/hr for anode refining roof vents.
    With regard to demographic impacts, due to the fact that the EPA is 
proposing that risks from emissions of air toxics from this major 
source category are unacceptable at baseline and since EPA is proposing 
new standards (as described above) which are expected to reduce risks 
to an acceptable level, EPA performed a post-control demographic 
analysis to identify how the estimated risks would be distributed among 
different demographic groups of the populations living within 5 km and 
within 50 km of the two major source facilities after the additional 
controls (described above) are in place. The methodology and the 
results of the post-control demographic analysis are presented in the 
technical report, Risk and Technology Review--Analysis of Demographic 
Factors for Populations Living Near Primary Copper Smelting Post-
Control Source Category Operations, which is available in the docket.
    This post-control demographic report indicates that for the major 
source category as a whole, average cancer risk for demographic groups 
would decrease as follows as a result of additional capture and control 
systems at the Freeport facility: Hispanic or Latino (4-in-1 million to 
3-in-1 million); Native American (2-in-1 million to 1-in-1 million); 
African American (10-in-1 million to 5-in-1 million); Other and 
Multiracial (5-in-1 million to 3-in-1 million); people living below the 
poverty level (4-in-1 million to 2-in-1 million); people 25 years old 
and older without a high school diploma (4-in-1 million to 2-in-1 
million); and people living in linguistic isolation (4-in-1 million to 
2-in-1 million). For the total population exposed to emissions from the 
source category, average cancer risk would be reduced from 4-in-1 
million to 2-in-1 million.
3. Ample Margin of Safety Analysis
    After identifying controls that would reduce risk to an acceptable 
level, the Agency next considered whether additional measures are 
required to provide an ample margin of safety to protect public health. 
In the ample margin of safety analysis, the Agency evaluated the cost 
and feasibility of available control technologies and other measures 
(such as work practices) that could be applied to the source category 
to further reduce the risk due to emissions of HAP.
    With regard to additional controls considered under the ample 
margin of safety analysis, as described in section IV.B.1, another 
emission point contributing significantly to risks at Freeport is the 
Aisle Scrubber, which is used to control the combination of secondary 
emissions from the converter plus the emissions exiting the baghouse 
used to control primary anode refining point source emissions. 
Therefore, the Agency estimated the costs to install an additional PM 
control device (e.g., a wet ESP) and the emissions and risks reductions 
that would be achieved. Based on that analysis, we estimate these 
controls would have capital costs of $50M and annualized costs of $13M 
and achieve about 7.6 tpy of metal HAP with cost effectiveness of $1.7M 
per ton of metal HAP. Based on risk modeling, the Agency estimates the 
addition of these controls (in addition to the controls for anode roof 
vent process fugitives described above) would reduce the maximum 3-
month ambient lead concentration near Freeport from 0.073 ug/m\3\ to 
0.024 ug/m\3\, the inhalation cancer MIR near Freeport would be reduced 
from 30 to 20-in-1 million, with 17,350 people exposed to a cancer risk 
greater than or equal to 1-in-1 million, a 34 percent reduction when 
compared to cancer risk from actual emissions. The maximum off-site 
acute HQ would remain the same with an HQ = 2. The additional control 
options changed the maximum acute off-site location, resulting in a 
lower potential for exposure. The acute arsenic HQ is based upon an 
REL, the acute REL represents a health-protective level of exposure, 
with effects not anticipated below those levels, even for repeated 
exposures; however, the level of exposure that would cause health 
effects is not specifically known. As the exposure concentration 
increases above the acute REL, the potential for effects increases. 
Based upon an acute HQ value of 2 for arsenic emissions based on the 
REL, and given the protective nature of the REL (as described 
previously in this preamble, in section III.C.3.c) and without any 
additional acute health benchmarks to apply to further characterize the 
potential for severe or reversible effects it is reasonable to assume 
that acute health risks from arsenic for this source category would be 
low.
    Given the relatively high estimated capital costs, uncertainties, 
and moderate risk reductions that would be achieved for populations 
living near these facilities, the Agency is not proposing these 
additional controls for the Aisle Scrubber at this time. Nevertheless, 
the Agency is soliciting comments regarding our analysis (including the 
costs, costs effectiveness, and risk reductions) and whether the EPA 
should establish more stringent standards to reduce HAP metal emissions 
from the Aisle Scrubber.
    The EPA also evaluated an option to reduce risks from the Asarco 
facility. In this case the Agency evaluated the potential to reduce 
process fugitive HAP metal emissions from the flash smelting furnace 
roof vents by installing hoods, ducts, fans, and an additional 
baghouse. Under this option, the Agency estimated capital costs of 
$19,107,200, annualized costs of $4,244,610, and approximately 1.08 tpy 
reduction of HAP metals, with cost effectiveness of $3,537,000 per ton 
of HAP metals. These controls would reduce the modeled inhalation 
cancer risk for Asarco (primarily due to arsenic emissions) from 60-in-
1 million to about 10-in-1 million. These controls would also reduce 
lead emissions and associated risk from lead exposures from Asarco to 
some extent. However, given the relatively high estimated capital 
costs, annualized costs, poor cost effectiveness, uncertainties, and 
limited risk reductions that would be achieved for populations living 
near these facilities, we are not proposing these additional controls 
for the flash smelting furnace at Asarco at this time. Nevertheless, we 
are soliciting comments regarding our analysis (including the costs, 
cost effectiveness, and risk reductions) and whether the EPA should 
establish more stringent standards to reduce HAP metal emissions from 
the Flash Furnace at Asarco.
    In addition to the controls described above, the Agency also 
evaluated the potential to propose additional work practices to reduce 
fugitive dust emissions, consistent with Asarco's

[[Page 1644]]

current consent decree. The additional work practices the Agency 
identified include the following:
     Routine cleaning of paved roads with a sweeper, vacuum or 
wet broom (in accordance with applicable recommendations by the 
manufacturer of the street sweeper, vacuum, or wet broom), with such 
cleaning to occur no less frequently than on a daily basis unless the 
roads have sufficient surface moisture such that fugitive dust is not 
generated.
     Chemical dust suppressants will be applied not less 
frequently than once per month at slag haul roads and not less 
frequently than every 6 weeks on all other unpaved roads unless the 
roads have sufficient surface moisture such that fugitive dust is not 
generated.
     Copper concentrate storage, handling, and unloading 
operations.
     The cargo compartment of all trucks or other motor 
vehicles (e.g., front-end loaders) when transporting bulk quantities of 
fugitive dust materials must be maintained to ensure:
    (i) The floor, sides, and/or tailgate(s) are free of holes or other 
openings.
    (ii) All loads of trucks containing copper concentrate arriving at 
the facility are covered with a tarp to prevent spills and fugitive 
emissions.
    (iii) Trucks are loaded only to such a level as to prevent spillage 
over the side.
    (iv) A speed limit of 15 mph is required.
    (v) All dust producing material internally transferred or moved by 
truck at the facility is covered with a tarp to prevent spills and 
fugitive emissions.
     Revert crushing operations and crushed revert storage.
     Scrubber liquid blowdown drying operations.
     Other site-specific sources of fugitive dust emissions 
that the Administrator or delegated permitting authority designate to 
be included in your fugitive dust control plan.
     For any element of the fugitive dust control plan that 
requires new construction at the facility, the owner or operator shall 
complete such construction, in accordance with the specifications and 
schedule set forth in the approved fugitive dust control plan.
     The fugitive dust control plan must be reviewed, updated 
(if necessary), and then approved by the permitting authority with each 
application for the Title V operating permit renewal pursuant to part 
70 or part 71 of this chapter and with each permit application for the 
construction or modification of lead-bearing fugitive dust generating 
sources.
    Since the facilities already need to implement most of these work 
practices per the consent decrees or state air permits, we expect there 
will be very minimal additional costs if these work practices are also 
incorporated into the NESHAP. The only additional costs would be a 
slight increase related to recordkeeping and reporting requirements. 
Furthermore, the Agency concludes that these additional work practices 
will achieve unquantified reductions of fugitive dust HAP metal 
emissions and associated human health risks. Therefore, under CAA 
section 112(f), as part of our ample margin of safety determination, 
the Agency is proposing that the facilities will need to develop and 
implement a more robust fugitive dust plan than currently required by 
the NESHAP. This plan would require, at a minimum, the specific work 
practices described above, but also could include other practices 
identified by the facilities (or the permitting authority to minimize 
these fugitive dust emissions).
    Finally, EPA considered the impact of the proposed standards on the 
distribution of post-control risks as outlined in the technical report, 
Risk and Technology Review--Analysis of Demographic Factors for 
Populations Living Near Primary Copper Smelting Post-Control Source 
Category Operations. The baseline risk analysis indicated the potential 
for elevated cancer risks associated with emissions from the major 
source category to disproportionately affect communities with 
environmental justice concerns, including low-income residents, Native 
Americans, and Hispanics living near these facilities. EPA also noted 
that the potential acute risks from arsenic emissions, and the highest 
estimated exposures due to lead emissions, are associated with the 
Freeport facility. The post-control analysis indicated that with the 
addition of controls proposed in this rulemaking, the cancer risks will 
be reduced from an estimated maximum individual excess cancer risk at 
Freeport from 80-in-1 million to 30-in-1 million, and noncancer risks 
will also be reduced significantly, substantially reducing risk among 
highly exposed individuals and reducing some of the risk disparities 
identified in the baseline (pre-control) scenario. Furthermore, the 
maximum modeled excess cancer risk for any person near Asarco is 60-in-
1 million. As a result, EPA concludes that the proposed standards 
provide an ample margin of safety to protect public health and notes 
that for the major source category as a whole, average cancer risk for 
each demographic group will be reduced.
    In summary, based on our ample margin of safety analysis, we are 
not proposing additional controls for the combined emissions stream 
from the anode refining furnace and secondary converter operations or 
the flash furnaces, as described above. Furthermore, the Agency did not 
identify any additional controls or measures to further reduce process 
fugitive emissions from the anode refining roof vents beyond those 
controls being proposed under the acceptability section (described 
above). However, the Agency is proposing additional work practices to 
limit fugitive dust emissions as part of the ample margin of safety 
analysis. Overall, the Agency proposes that with the additional 
controls for the anode refining furnace process fugitive roof vents 
described above (under the acceptability section), and the additional 
fugitive dust work practice standards being proposed based on our ample 
margin of safety analysis, the NESHAP will provide an ample margin of 
safety to protect public health. The acute arsenic HQ of 2 is based 
upon an REL, the acute REL represents a health-protective level of 
exposure, with effects not anticipated below those levels, even for 
repeated exposures; however, the level of exposure that would cause 
health effects is not specifically known. As the exposure concentration 
increases above the acute REL, the potential for effects increases. 
Based upon an acute HQ value of 2 for arsenic emissions, without any 
additional acute health benchmarks to apply to further characterize the 
potential for severe or reversible effects it is reasonable to assume 
that acute health risks from arsenic for this source category would be 
low.
4. Adverse Environmental Effect
    Based on the results of the environmental risk screening analysis, 
the Agency does not expect an adverse environmental effect as a result 
of HAP emissions from this source category.

D. What are the results and proposed decisions based on our technology 
review?

    Under the technology review, the EPA searched, reviewed, and 
considered several sources of information to determine whether there 
have been developments in practices, processes, and control 
technologies as required by section 112(d)(6) of the CAA. The EPA 
researched practices, processes, and control technologies through a 
literature review to identify advancements in processes and control 
technologies in the primary copper smelting industry with a view toward 
identifying ``developments'' in practices, processes,

[[Page 1645]]

and control. In conducting the technology review, the Agency examined 
information in the RBLC to identify technologies in use and determine 
whether there have been relevant developments in practices, processes, 
or control technologies. The RBLC is a database that contains case-
specific information on air pollution technologies that have been 
required to reduce the emissions of air pollutants from stationary 
sources. Potential developments in the industry were discussed with 
representatives of the primary copper smelting companies. In addition, 
state permits as well as recent consent decrees or consent orders 
between the EPA or the ADEQ and primary copper smelters were reviewed 
to assess control technologies at primary copper smelting plants. To 
identify developments, the Agency evaluated whether there were 
improvements in processes and control technologies available at the 
time the standards were promulgated that could reduce emissions of the 
regulated pollutants. We also evaluated whether there were processes 
and control technologies that were not available at the time the 
standards were promulgated that could reduce emissions of the regulated 
pollutants.
    Concentrate dryers are used at the Kennecott Utah facility and the 
Asarco Hayden plant. The Freeport-McMoRan Miami smelter uses a wet feed 
and has no dryer. PM control at the Kennecott dryer consists of a 
baghouse and a scrubber. PM emissions from the Asarco dryers are 
controlled using baghouses.
    Smelting furnaces at Asarco are controlled by a venturi scrubber 
followed by a wet gas cleaning system and an acid plant. Process gases 
from the Kennecott smelting furnace are exhausted to a waste heat 
boiler and then to an ESP, a wet scrubber, and a wet ESP. The off-gas 
from the Freeport smelting furnace is routed through a waste heat 
boiler where entrained dust settles out and is then routed to an ESP.
    Matte drying and grinding are performed at the Asarco and Freeport 
facilities. Emissions are controlled using baghouses.
    The two major sources, Asarco and Freeport, use batch converters. 
Controls include combinations of baghouses, scrubbers, and ESPs. 
Process gases at the Kennecott continuous converter are exhausted to a 
waste heat boiler, an ESP, a wet scrubber, and then to a wet ESP.
    Slag cleaning emissions at Kennecott are vented to scrubbers. The 
slag cleaning furnace at Asarco has been decommissioned and the slag is 
allowed to cool and is sent back for additional processing for 
additional copper recovery. At the Freeport facility, the slag is sent 
to an electric furnace, and off-gas from the furnace is cooled with 
water sprays and then ducted to the acid plant.
    Exhaust gases from anode refining furnaces are controlled by 
baghouses. Secondary gas systems typically exhaust to either a 
baghouse, a baghouse and a scrubber, or a scrubber and wet ESP.
    All three primary copper smelting facilities operate under a 
fugitive dust control plan. Controls include the use of water sprays, 
chemical dust suppressants, placing material stockpiles below grade, 
and installing wind screens or wind fences around the source.
1. 40 CFR Part 63, Subpart QQQ
    The current NESHAP for major source primary copper smelting 
facilities (40 CFR part 63, subpart QQQ) establishes numeric emission 
limits for PM, a surrogate for metal HAP, for copper concentrate 
dryers, smelting furnaces, slag cleaning vessels, and existing copper 
converters. The standard for new converters prohibits batch converters. 
An opacity limit applies to the converter building during performance 
testing. A fugitive dust control plan is required for the control of 
fugitive emissions. This subpart also establishes requirements to 
demonstrate initial and continuous compliance with all applicable 
emission limitations, work practice standards, and operation and 
maintenance requirements in this subpart. The requirements apply to 
primary copper smelters that are (or are part of) a major source of HAP 
emissions and that use batch copper converters.
    As part of the technology review for the major source category, the 
Agency identified previously unregulated processes and pollutants, and 
are regulating them under CAA section 112(d)(2) and (3), as described 
in section IV.A, above; these new provisions also are being proposed 
under CAA section 112(f)(2), as described in section IV.C, above. With 
regard to the emissions sources at major primary copper smelting 
facilities, including sources of fugitive dust emissions, the Agency 
did not identify any developments in practices, processes, or control 
technologies beyond those described under the ample margin of safety 
analysis above.
2. 40 CFR Part 63, Subpart EEEEEE
    The current NESHAP for area source primary copper smelting facility 
(40 CFR part 63, subpart EEEEEE) establishes numeric emission limits 
for PM (a surrogate for metal HAP), emitted from copper concentrate 
dryers, smelting vessels, converting vessels, matte drying and grinding 
plants, secondary gas systems, and anode refining departments. This 
subpart also requires work practices to ensure the capture of gases and 
fumes from the transfer of molten materials and their conveyance to 
control devices, provisions to monitor PM emissions for initial and 
continuous compliance, work practice standards, and operation and 
maintenance. With regard to the emissions sources at the area source 
primary copper smelting facility, including sources of fugitive dust 
emissions, the Agency did not identify any developments in practices, 
processes, or control technologies.
    For more details, refer to the document, Technology Review for the 
Primary Copper Smelting Source Category, which is available in Docket 
ID No. EPA-HQ-OAR-2020-0430.

E. What other actions are we proposing?

    In addition to the proposed actions described above, the EPA is 
proposing additional revisions to the NESHAP. The EPA is proposing 
revisions to the SSM provisions of the MACT rule in order to ensure 
that they are consistent with the decision in Sierra Club v. EPA, 551 
F. 3d 1019 (D.C. Cir. 2008), in which the court vacated two provisions 
that exempted sources from the requirement to comply with otherwise 
applicable CAA section 112(d) emission standards during periods of SSM. 
The Agency is proposing various other changes to the NESHAP, including 
the following: (1) Require electronic reporting of performance test 
results and notification of compliance reports; (2) revising the 
applicability under section 63.1441 to clarify that the NESHAP applies 
to major source smelting facilities that use any type of converter, not 
just batch converters; (3) revising the testing requirements under 
section 63.1450 to clarify that facilities must test for filterable 
particulate, not total particulate, (4) adding test methods for 
mercury, PM10 and fugitive PM and updating test methods that 
are incorporated by reference; and (5) revising the definitions under 
section 63.1459 by changing the term ``smelting furnace'' to ``smelting 
vessel'' to be consistent with the definition in the area source rule, 
subpart EEEEEE. Our analyses and proposed changes related to these 
issues are discussed below.
1. SSM
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C. 
Cir. 2008), the court vacated portions of two provisions in the EPA's 
CAA section 112

[[Page 1646]]

regulations governing the emissions of HAP during periods of SSM. 
Specifically, the court vacated the SSM exemption contained in 40 CFR 
63.6(f)(1) and 40 CFR 63.6(h)(1), holding that under section 302(k) of 
the CAA, emissions standards or limitations must be continuous in 
nature and that the SSM exemption violates the CAA's requirement that 
some section 112 standards apply continuously.
    The EPA is proposing the elimination of the SSM exemptions in these 
rules. Consistent with Sierra Club v. EPA, the Agency is proposing 
standards in these rules that apply at all times. The Agency is also 
proposing several revisions to Table 1 to subpart QQQ and Table 1 to 
subpart EEEEEE (the General Provisions Applicability Tables) as is 
explained in more detail below. For example, the Agency is proposing to 
eliminate the incorporation of the General Provisions' requirement that 
the source develop an SSM plan. The EPA is also proposing to eliminate 
and revise certain recordkeeping and reporting requirements related to 
the SSM exemption as further described below.
    The EPA has attempted to ensure that the provisions the Agency is 
proposing to eliminate are inappropriate, unnecessary, or redundant in 
the absence of the SSM exemption. The EPA specifically is seeking 
comments on whether the Agency has successfully done so.
    In proposing the standards in these rules, the EPA has considered 
startup and shutdown periods and, for the reasons explained below, is 
not proposing alternative standards for those periods. The associated 
control devices are operational before startup and during shutdown of 
the affected sources at primary copper smelting facilities. Therefore, 
we expect that emissions during startup and shutdown would be no higher 
than emissions during normal operations. We know of no reason why the 
existing standards should not apply at all times.
    Periods of startup, normal operations, and shutdown are all 
predictable and routine aspects of a source's operations. Malfunctions, 
in contrast, are neither predictable nor routine. Instead they are, by 
definition, sudden, infrequent, and not reasonably preventable failures 
of emissions control, process, or monitoring equipment. (40 CFR 63.2) 
(Definition of malfunction). The EPA interprets CAA section 112 as not 
requiring emissions that occur during periods of malfunction to be 
factored into development of CAA section 112 standards and this reading 
has been upheld as reasonable by the court in U.S. Sugar Corp. v. EPA, 
830 F.3d 579, 606-610 (2016). Under CAA section 112, emissions 
standards for new sources must be no less stringent than the level 
``achieved'' by the best controlled similar source and for existing 
sources generally must be no less stringent than the average emission 
limitation ``achieved'' by the best performing 12 percent of sources in 
the category. There is nothing in CAA section 112 that directs the 
Agency to consider malfunctions in determining the level ``achieved'' 
by the best performing sources when setting emission standards. As the 
court has recognized, the phrase ``average emissions limitation 
achieved by the best performing 12 percent of'' sources ``says nothing 
about how the performance of the best units is to be calculated.'' 
Nat'l Ass'n of Clean Water Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. 
Cir. 2013). While the EPA accounts for variability in setting emissions 
standards, nothing in CAA section 112 requires the Agency to consider 
malfunctions as part of that analysis. The EPA is not required to treat 
a malfunction in the same manner as the type of variation in 
performance that occurs during routine operations of a source. A 
malfunction is a failure of the source to perform in a ``normal or 
usual manner'' and no statutory language compels the EPA to consider 
such events in setting CAA section 112 standards.
    Similarly, although standards for area sources are not required to 
be set based on ``best performers,'' the EPA is not required to 
consider malfunctions in determining what is ``generally available.''
    As the court recognized in U.S. Sugar Corp, accounting for 
malfunctions in setting standards would be difficult, if not 
impossible, given the myriad different types of malfunctions that can 
occur across all sources in the category and given the difficulties 
associated with predicting or accounting for the frequency, degree, and 
duration of various malfunctions that might occur. Id. at 608 (``the 
EPA would have to conceive of a standard that could apply equally to 
the wide range of possible boiler malfunctions, ranging from an 
explosion to minor mechanical defects. Any possible standard is likely 
to be hopelessly generic to govern such a wide array of 
circumstances.''). As such, the performance of units that are 
malfunctioning is not ``reasonably'' foreseeable. See, e.g., Sierra 
Club v. EPA, 167 F.3d 658, 662 (D.C. Cir. 1999) (``The EPA typically 
has wide latitude in determining the extent of data-gathering necessary 
to solve a problem. The EPA generally defers to an agency's decision to 
proceed on the basis of imperfect scientific information, rather than 
to `invest the resources to conduct the perfect study.' ''). See also, 
Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (``In the 
nature of things, no general limit, individual permit, or even any 
upset provision can anticipate all upset situations. After a certain 
point, the transgression of regulatory limits caused by `uncontrollable 
acts of third parties,' such as strikes, sabotage, operator 
intoxication or insanity, and a variety of other eventualities, must be 
a matter for the administrative exercise of case-by-case enforcement 
discretion, not for specification in advance by regulation.''). In 
addition, emissions during a malfunction event can be significantly 
higher than emissions at any other time of source operation. For 
example, if an air pollution control device with 99 percent removal 
goes off-line as a result of a malfunction (as might happen if, for 
example, the bags in a baghouse catch fire) and the emission unit is a 
steady state type unit that would take days to shut down, the source 
would go from 99 percent control to zero control until the control 
device was repaired. The source's emissions during the malfunction 
would be 100 times higher than during normal operations. As such, the 
emissions over a 4-day malfunction period would exceed the annual 
emissions of the source during normal operations. As this example 
illustrates, accounting for malfunctions could lead to standards that 
are not reflective of (and significantly less stringent than) levels 
that are achieved by a well-performing non-malfunctioning source. It is 
reasonable to interpret CAA section 112 to avoid such a result. The 
EPA's approach to malfunctions is consistent with CAA section 112 and 
is a reasonable interpretation of the statute.
    Although no statutory language compels the EPA to set standards for 
malfunctions, the EPA has the discretion to do so where feasible. For 
example, in the Petroleum Refinery Sector Risk and Technology Review, 
the EPA established a work practice standard for unique types of 
malfunction that result in releases from pressure relief devises (PRDs) 
or emergency flaring events because the EPA had information to 
determine that such work practices reflected the level of control that 
applies to the best performers. 80 FR 75178, 75211-14 (Dec. 1, 2015). 
The EPA will consider whether circumstances warrant setting standards 
for a particular type of malfunction and, if so, whether the EPA

[[Page 1647]]

has sufficient information to identify the relevant best performing 
sources and establish a standard for such malfunctions. The Agency also 
encourages commenters to provide any such information.
    Based on the EPA's knowledge of the processes and engineering 
judgment, malfunctions in the Primary Copper Smelting source category 
are considered unlikely to result in a violation of the standard. 
Affected sources at primary copper smelting plants are controlled with 
add-on air pollution control devices which will continue to function in 
the event of a process upset. Also, processes in the industry are 
typically equipped with controls that will not allow startup of the 
emission source until the associated control device is operating and 
will shut down the emission source if the associated controls 
malfunction. Furnaces used in primary copper smelting, which are the 
largest sources of HAP emissions, typically operate continuously for 
long periods of time with no significant spikes in emissions. These 
minimal fluctuations in emissions are controlled by the existing add-on 
air pollution control devices used at all plants in the industry.
    In the unlikely event that a source fails to comply with the 
applicable CAA section 112(d) standards as a result of a malfunction 
event, the EPA would determine an appropriate response based on, among 
other things, the good faith efforts of the source to minimize 
emissions during malfunction periods, including preventative and 
corrective actions, as well as root cause analyses to ascertain and 
rectify excess emissions. The EPA would also consider whether the 
source's failure to comply with the CAA section 112(d) standard was, in 
fact, sudden, infrequent, not reasonably preventable, and was not 
instead caused, in part, by poor maintenance or careless operation. 40 
CFR 63.2 (Definition of malfunction).
    If the EPA determines in a particular case that an enforcement 
action against a source for violation of an emission standard is 
warranted, the source can raise any and all defenses in that 
enforcement action and the federal district court will determine what, 
if any, relief is appropriate. The same is true for citizen enforcement 
actions. Similarly, the presiding officer in an administrative 
proceeding can consider any defense raised and determine whether 
administrative penalties are appropriate.
    In summary, the EPA interpretation of the CAA, particularly section 
112, is reasonable and encourages practices that will avoid 
malfunctions. Administrative and judicial procedures for addressing 
exceedances of the standards fully recognize that violations may occur 
despite good faith efforts to comply and can accommodate those 
situations. U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606-610 (2016).
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.6(e)(1)(i) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' Section 63.6(e)(1)(i) describes the general duty to minimize 
emissions. Some of the language in that section is no longer necessary 
or appropriate in light of the elimination of the SSM exemption. The 
Agency is proposing instead to add general duty regulatory text at 40 
CFR 63.1447(a) (subpart QQQ) that reflects the general duty to minimize 
emissions while eliminating the reference to periods covered by an SSM 
exemption. The general duty to minimize emissions at existing area 
sources (subpart EEEEEE), including periods of SSM, are contained in 
sections 63.11147(c) and 63.11148(f). The general duty to minimize 
emissions at new sources are being proposed in 63.11149(c)(3). The 
current language in 40 CFR 63.6(e)(1)(i) characterizes what the general 
duty entails during periods of SSM. With the elimination of the SSM 
exemption, there is no need to differentiate between normal operations, 
startup and shutdown, and malfunction events in describing the general 
duty. Therefore, the language the EPA is proposing for subpart QQQ and 
subpart EEEEEE do not include that language from 40 CFR 63.6(e)(1).
    The EPA is also proposing to revise the General Provisions table 
(Table 1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.6(e)(1)(ii) by changing the ``yes'' in the column titled ``Applies 
to Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' 
to a ``no.'' Section 63.6(e)(1)(ii) imposes requirements that are not 
necessary with the elimination of the SSM exemption or are redundant 
with the general duty requirement being added at 40 CFR 63.1447(a) 
(subpart QQQ) and that are already required for existing sources in 40 
CFR 63.11147(c) and 63.11148(f) and are proposed for new sources in 
63.11149(c)(3).
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.6(e)(3) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' Generally, these paragraphs require development of an SSM 
plan and specify SSM recordkeeping and reporting requirements related 
to the SSM plan. As noted, the EPA is proposing to remove the SSM 
exemptions. Therefore, affected units will be subject to an emission 
standard during such events. The applicability of a standard during 
such events will ensure that sources have ample incentive to plan for 
and achieve compliance and, thus, the SSM plan requirements are no 
longer necessary.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.6(f)(1) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' The current language of 40 CFR 63.6(f)(1) exempts sources 
from non-opacity standards during periods of SSM. As discussed above, 
the court in Sierra Club v. EPA vacated the exemptions contained in 
this provision and held that the CAA requires that some CAA section 112 
standards apply continuously. Consistent with Sierra Club v. EPA, the 
EPA is proposing to revise standards in these rules to apply at all 
times.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart EEEEEE) entry for 40 CFR 63.6(h)(1) by changing the 
``yes'' in the column titled ``Applies to Subpart EEEEEE'' to a ``no.'' 
The entry for 40 CFR 63.6(h) in Table 1 to subpart QQQ is already a 
``no.' The current language of 40 CFR 63.6(h)(1) exempts sources from 
opacity standards during periods of SSM. As discussed above, the court 
in Sierra Club vacated the exemptions contained in this provision and 
held that the CAA requires that some CAA section 112 standard apply 
continuously. Consistent with Sierra Club, the EPA is proposing to 
revise standards in this rule to apply at all times.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.7(e)(1) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' Section 63.7(e)(1) describes performance testing 
requirements. The EPA is instead proposing to add a performance testing 
requirement at 40 CFR 63.1450(a) and (b) (subpart QQQ) and 
63.11148(e)(3) (subpart EEEEEE). The performance testing requirements 
the Agency is proposing to add differ from the General Provisions 
performance testing

[[Page 1648]]

provisions in several respects. The regulatory text does not include 
the language in 40 CFR 63.7(e)(1) that restated the SSM exemption and 
language that precluded startup and shutdown periods from being 
considered ``representative'' for purposes of performance testing. As 
in 40 CFR 63.7(e)(1), performance tests conducted under this subpart 
should not be conducted during malfunctions because conditions during 
malfunctions are often not representative of normal operating 
conditions. The EPA is proposing to add language that requires the 
owner or operator to 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. Section 63.7(e) requires that the owner or operator make 
such records ``as may be necessary to determine the condition of the 
performance test'' available to the Administrator upon request but does 
not specifically require the information to be recorded. The regulatory 
text the EPA is proposing to add to these provisions builds on that 
requirement and makes explicit the requirement to record the 
information.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.8(c)(1)(i) and (iii) by changing the ``yes'' in the column titled 
``Applies to Subpart QQQ'' and in the column titled ``Applies to 
Subpart EEEEEE'' to a ``no.'' The cross-references to the general duty 
and SSM plan requirements in those subparagraphs are not necessary in 
light of other requirements of 40 CFR 63.8 that require good air 
pollution control practices (40 CFR 63.8(c)(1)) and that set out the 
requirements of a quality control program for monitoring equipment (40 
CFR 63.8(d)).
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.8(d)(3) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' The final sentence in 40 CFR 63.8(d)(3) refers to the General 
Provisions' SSM plan requirement which is no longer applicable. The EPA 
is proposing to add to the rules at 40 CFR 63.1456(a)(4)(iii) in 
subpart QQQ and 63.11149(b)(3) in subpart EEEEEE text that is identical 
to 40 CFR 63.8(d)(3) except that the final sentence is replaced with 
the following sentence: ``The program of corrective action should be 
included in the plan required under Sec.  63.8(d)(2).''
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(b)(2)(i) by changing the ``yes'' in the column titled ``Applies 
to Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' 
to a ``no.'' Section 63.10(b)(2)(i) describes the recordkeeping 
requirements during startup and shutdown. These recording provisions 
are no longer necessary because the EPA is proposing that recordkeeping 
and reporting applicable to normal operations will apply to startup and 
shutdown. In the absence of special provisions applicable to startup 
and shutdown, such as a startup and shutdown plan, there is no reason 
to retain additional recordkeeping for startup and shutdown periods.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(b)(2)(ii) by changing the ``yes'' in the column titled ``Applies 
to Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' 
to a ``no.'' Section 63.10(b)(2)(ii) describes the recordkeeping 
requirements during a malfunction. The EPA is proposing to add such 
requirements to 40 CFR 63.1456 (subpart QQQ) and 40 CFR 63.11149(g) 
(subpart EEEEEE). The regulatory text the Agency is proposing to add 
differs from the General Provisions it is replacing in that the General 
Provisions requires the creation and retention of a record of the 
occurrence and duration of each malfunction of process, air pollution 
control, and monitoring equipment. The EPA is proposing that this 
requirement apply to any failure to meet an applicable standard and is 
requiring that the source record the date, time, and duration of the 
failure rather than the ``occurrence.'' The EPA is also proposing to 
add a requirement that sources keep records that include a list of the 
affected source or equipment and actions taken to minimize emissions, 
an estimate of the quantity of each regulated pollutant emitted over 
the standard for which the source failed to meet the standard, and a 
description of the method used to estimate the emissions. Examples of 
such methods would include product-loss calculations, mass balance 
calculations, measurements when available, or engineering judgment 
based on known process parameters. The EPA is proposing to require that 
sources keep records of this information to ensure that there is 
adequate information to allow the EPA to determine the severity of any 
failure to meet a standard, and to provide data that may document how 
the source met the general duty to minimize emissions when the source 
has failed to meet an applicable standard.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(b)(2)(iv) by changing the ``yes'' in the column titled ``Applies 
to Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' 
to a ``no.'' When applicable, the provision requires sources to record 
actions taken during SSM events when actions were inconsistent with 
their SSM plan. The requirement is no longer appropriate because SSM 
plans will no longer be required. The requirement previously applicable 
under 40 CFR 63.10(b)(2)(iv)(B) to record actions to minimize emissions 
and record corrective actions is now applicable by reference to 40 CFR 
63.1456 (subpart QQQ) and 40 CFR 63.11149.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(b)(2)(v) by changing the ``yes'' in the column titled ``Applies 
to Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' 
to a ``no.'' When applicable, the provision requires sources to record 
actions taken during SSM events to show that actions taken were 
consistent with their SSM plan. The requirement is no longer 
appropriate because SSM plans will no longer be required.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(c)(15) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart EEEEEE'' to 
a ``no.'' The EPA is proposing that 40 CFR 63.10(c)(15) no longer 
apply. When applicable, the provision allows an owner or operator to 
use the affected source's SSM plan or records kept to satisfy the 
recordkeeping requirements of the SSM plan, specified in 40 CFR 
63.6(e), to also satisfy the requirements of 40 CFR 63.10(c)(10) 
through (12). The EPA is proposing to eliminate this requirement 
because SSM plans would no longer be required, and therefore 40 CFR 
63.10(c)(15) no longer serves any useful purpose for affected units.
    The EPA is proposing to revise the General Provisions table (Table 
1 to subpart QQQ and Table 1 to subpart EEEEEE) entry for 40 CFR 
63.10(d)(5) by changing the ``yes'' in the column titled ``Applies to 
Subpart QQQ'' and in the column titled ``Applies to Subpart

[[Page 1649]]

EEEEEE'' to a ``no.'' Section 63.10(d)(5) describes the reporting 
requirements for SSM. To replace the General Provisions reporting 
requirement, the EPA is proposing to add reporting requirements to 40 
CFR 63.1455 (subpart QQQ) and 40 CFR 63.11147, 63.11148, and 63.11149 
(subpart EEEEEE). The replacement language differs from the General 
Provisions requirement in that it eliminates periodic SSM reports as a 
stand-alone report. The Agency is proposing language that requires 
sources that fail to meet an applicable standard at any time to report 
the information concerning such events in the semi-annual or other 
reporting period deviation or excess emission report already required 
under these rules. The Agency is proposing that the report must contain 
the number, date, time, duration, and the cause of such events 
(including unknown cause, if applicable), a list of the affected 
sources or equipment, an estimate of the quantity of each regulated 
pollutant emitted over any emission limit, and a description of the 
method used to estimate the emissions.
    Examples of such methods would include product-loss calculations, 
mass balance calculations, measurements when available, or engineering 
judgment based on known process parameters. The EPA is proposing this 
requirement to ensure that there is adequate information to determine 
compliance, to allow the EPA to determine the severity of the failure 
to meet an applicable standard, and to provide data that may document 
how the source met the general duty to minimize emissions during a 
failure to meet an applicable standard.
    The EPA will no longer require owners or operators to determine 
whether actions taken to correct a malfunction are consistent with an 
SSM plan, because plans would no longer be required. The proposed 
amendments therefore eliminate any cross reference to 40 CFR 
63.10(d)(5)(i) that contains the description of the previously required 
SSM report format and submittal schedule from this section. These 
specifications are no longer necessary because the events will be 
reported in otherwise required reports with similar format and 
submittal requirements.
2. Electronic Reporting
    The EPA is proposing that owners and operators of Primary Copper 
Smelting facilities submit electronic copies of required performance 
test reports, through the EPA's Central Data Exchange (CDX) using the 
Compliance and Emissions Data Reporting Interface (CEDRI). A 
description of the electronic data submission process is provided in 
the memorandum Electronic Reporting Requirements for New Source 
Performance Standards (NSPS) and National Emission Standards for 
Hazardous Air Pollutants (NESHAP) Rules, available in the docket for 
this action. The proposed rule requires that performance test results 
collected using test methods that are supported by the EPA's Electronic 
Reporting Tool (ERT) as listed on the ERT website at the time of the 
test be submitted in the format generated through the use of the ERT or 
an electronic file consistent with the xml schema on the ERT website, 
and other performance test results be submitted in portable document 
format (PDF) using the attachment module of the ERT. Similarly, 
performance evaluation results of continuous emissions monitoring 
systems (CEMS) measuring relative accuracy test audit (RATA) pollutants 
that are supported by the ERT at the time of the test must be submitted 
in the format generated through the use of the ERT or an electronic 
file consistent with the xml schema on the ERT website, and other 
performance evaluation results be submitted in PDF using the attachment 
module of the ERT.
    Additionally, the EPA has identified two broad circumstances in 
which electronic reporting extensions may be provided. These 
circumstances are (1) outages of the EPA's CDX or CEDRI, which preclude 
an owner or operator from accessing the system and submitting required 
reports, and (2) force majeure events, which are defined as events that 
will be or have been caused by circumstances beyond the control of the 
affected facility, its contractors, or any entity controlled by the 
affected facility that prevent an owner or operator from complying with 
the requirement to submit a report electronically. Examples of force 
majeure events are acts of nature, acts of war or terrorism, or 
equipment failure or safety hazards beyond the control of the facility. 
The EPA is providing these potential extensions to protect owners and 
operators from noncompliance in cases where they cannot successfully 
submit a report by the reporting deadline for reasons outside of their 
control. In both circumstances, the decision to accept the claim of 
needing additional time to report is within the discretion of the 
Administrator, and reporting should occur as soon as possible.
    The electronic submittal of the reports addressed in this proposed 
rulemaking will increase the usefulness of the data contained in those 
reports, is in keeping with current trends in data availability and 
transparency, will further assist in the protection of public health 
and the environment, will improve compliance by facilitating the 
ability of regulated facilities to demonstrate compliance with 
requirements and by facilitating the ability of delegated state, local, 
tribal, and territorial air agencies and the EPA to assess and 
determine compliance, and will ultimately reduce burden on regulated 
facilities, delegated air agencies, and the EPA. Electronic reporting 
also eliminates paper-based, manual processes, thereby saving time and 
resources, simplifying data entry, eliminating redundancies, minimizing 
data reporting errors, and providing data quickly and accurately to the 
affected facilities, air agencies, the EPA, and the public. Moreover, 
electronic reporting is consistent with the EPA's plan to implement 
Executive Order 13563 and is in keeping with the EPA's agency-wide 
policy developed in response to the White House's Digital Government 
Strategy. For more information on the benefits of electronic reporting, 
see the memorandum Electronic Reporting Requirements for New Source 
Performance Standards (NSPS) and National Emission Standards for 
Hazardous Air Pollutants (NESHAP) Rules, referenced earlier in this 
section.
3. Other Changes
    As mentioned above, we are also proposing four minor changes to 
major source NESHAP to clarify an applicability provision, update and 
clarify the testing requirements for PM, add a test method for mercury, 
and revise a definition. These changes are explained further in the 
following paragraphs.
    The EPA is proposing to revise the applicability description under 
section 63.1441 to clarify that the NESHAP applies to major source 
smelting facilities that use any type of converter, not just batch 
converters because the current definition limits applicability to only 
major sources that use batch converters. The major source NESHAP should 
apply to any Primary Copper major source regardless of what type of 
converter they use. Therefore, we are proposing this change.
    With regard to revisions to testing requirements, the Agency is 
proposing to revise the wording in section 63.1450 for clarification 
that the facilities must test for filterable particulate, not total 
particulate. The test methods in 63.1450(a) have not changed for PM 
from the existing regulation. The methods in the existing regulation 
(Methods 5, 5D, and 17) are methods for filterable PM. Total PM 
includes

[[Page 1650]]

filterable PM and condensable PM. The condensable PM test method 
(Method 202) is not included in the existing regulation for the 
emission standards set in 2002. In addition, the Agency is proposing to 
add the appropriate test methods for mercury, PM10 and 
fugitive PM and updating test methods that are incorporated by 
reference because the affected facilities will need to know what test 
methods they need to use to demonstrate compliance with the new 
standards.
    Finally, the EPA is proposing to revise the definitions under 
section 63.1459 by changing the term ``smelting furnace'' to ``smelting 
vessel'' to be consistent with the definition in the area source rule, 
subpart EEEEEE because we think it is appropriate that both rules 
include the broader definition of smelting vessel, which is already in 
the area source rule. The specific definition is as follows: Smelting 
vessel means a furnace, reactor, or other type of vessel in which 
copper ore concentrate and fluxes are smelted to form a molten mass of 
material containing copper matte and slag. Other copper-bearing 
materials may also be charged to the smelting vessel.

F. What compliance dates are we proposing?

    The EPA is proposing that existing facilities must comply with the 
BTF PM limits for the anode refining process fugitive roof vents within 
2 years after promulgation of the final rule. The EPA is proposing 2 
years for compliance because we expect the facility will need this much 
time to design and construct the necessary capture and control 
equipment described above. The reason the Agency is not proposing more 
than 2 years is because these controls are needed to achieve acceptable 
risks pursuant to CAA section 112(f), and section 112(f) only allows up 
to 2 years to comply with standards promulgated pursuant section 
112(f).
    For the new facility-wide mercury limits, new PM limits for anode 
refining point sources, and new PM limits for converter and smelting 
furnace roof vents, the Agency is proposing that existing facilities 
must comply within 1 year after promulgation of the final rule. For all 
other changes proposed in this action the Agency is proposing that 
existing facilities must comply within 180 days after promulgation of 
the final rule. All new or reconstructed facilities must comply with 
all requirements in the final rule upon startup. Our experience with 
similar industries that are required to convert reporting mechanisms, 
install necessary hardware and software, become familiar with the 
process of submitting performance test results electronically through 
the EPA's CEDRI, test these new electronic submission capabilities, 
reliably employ electronic reporting, and convert logistics of 
reporting processes to different time-reporting parameters shows that a 
time period of a minimum of 90 days, but more typically 180 days, is 
generally necessary to successfully complete these changes. Our 
experience with similar industries further shows that this sort of 
regulated facility generally requires a time period of 180 days to read 
and understand the amended rule requirements, 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, 
adjust parameter monitoring and recording systems to accommodate 
revisions, and update their operations to reflect the revised 
requirements.
    From our assessment of the time frame needed for compliance with 
the revised requirements, the EPA considers the periods of 2 years, 1 
year, and 180 days to be the most expeditious compliance period 
practicable for each of the standards described above, respectively, 
and, thus, is proposing that existing affected sources be in compliance 
with all of this regulation's revised requirements within these 
timeframes.
    For the MACT floor PM limit, the EPA is proposing in the subpart 
QQQ rule for anode refining point sources, we are proposing a 
compliance period of 1 year. Although this is a new requirement, the 
major source facilities are currently meeting the limit and the Agency 
expects minimal impact.
    For the proposed BTF limit for mercury for existing sources in 
subpart QQQ, the Agency is proposing a compliance period of 3 years. 
The EPA is providing 3 years to comply with the mercury standard 
because the facilities need time to hire a consultant to design the new 
control systems, establish contracts with construction companies and/or 
air pollution control installation experts to reconfigure equipment, 
and build and install new duct work, fans, and control systems. The 
facilities also need time to establish contracts with testing companies 
and arrange for and conduct the performance testing.
    For affected facilities that commence construction or 
reconstruction after January 11, 2022, owners or operators must comply 
with all requirements of the subpart, including all the amendments 
being proposed, no later than the effective date of the final rule or 
upon startup, whichever is later.
    For the proposed subpart QQQ PM standard for new converters, the 
Agency is proposing that all new or reconstructed facilities must 
comply with this requirement upon startup. As no new converters are 
expected to come online in the near future, the Agency does not expect 
there to be an issue with the proposed compliance period.

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    The Primary Copper Smelting source category includes any facility 
that uses a pyrometallurgical process to extract copper from copper 
sulfide ore concentrates, native ore concentrates, or other copper 
bearing minerals. There are currently three copper smelting facilities 
in the United States: Two are major sources and one is an area source. 
No new copper smelting facilities are currently being constructed or 
are planned in the near future.
1. 40 CFR Part 63, Subpart QQQ
    The affected sources subject to 40 CFR part 63, subpart QQQ, the 
major source NESHAP, are copper concentrate dryers, smelting furnaces, 
slag cleaning vessels, copper converter departments, and fugitive 
emission sources.
2. 40 CFR Part 63, Subpart EEEEEE
    Under 40 CFR part 63, subpart EEEEEE, the area source NESHAP, the 
affected sources are copper concentrate dryers, smelting vessels, 
converting vessels, matte drying and grinding plant, secondary gas 
systems, anode refining furnaces, and anode shaft furnaces.

B. What are the air quality impacts?

1. 40 CFR Part 63, Subpart QQQ
    The proposed amendments in this action would achieve about 4.26 tpy 
reduction of HAP metals emissions (primarily lead, arsenic and cadmium 
from anode refining operations and mercury from furnaces and 
converters). In this action, the Agency is also proposing additional 
work practices that the Agency thinks will achieve some additional 
unquantified HAP emissions reductions. These proposed amendments will 
also reduce risks to public health and the environment, as described 
above in this preamble.
    Furthermore, the Agency is proposing new standards for process 
fugitive PM emissions from furnaces and converters. The EPA does not 
expect to achieve reductions in emissions with these new standards. 
However, these standards will ensure that the emissions remain 
controlled and minimized moving

[[Page 1651]]

forward. The proposed amendments also include removal of the SSM 
exemptions.
2. 40 CFR Part 63, Subpart EEEEEE
    There are no air quality impacts resulting from the proposed 
amendments under 40 CFR part 63, subpart EEEEEE.

C. What are the cost impacts?

1. 40 CFR Part 63, Subpart QQQ
    As described above, the proposed standards for anode refining 
process fugitive emissions and BTF standard for mercury will require 
estimated capital costs of $7,331,000 and annualized costs of 
$2,299,000 for the Freeport facility (2019 dollars). The Asarco 
facility will incur estimated costs of about $95,000 per year to 
complete compliance testing for all the proposed emissions standards. 
Freeport already conducts annual testing of these units pursuant to 
state ADEQ requirements; therefore, the Agency does not expect Freeport 
to incur new testing costs. With regard to the proposed electronic 
reporting requirements, which will eliminate paper-based manual 
processes, the EPA expects a small initial unquantified cost to 
transition to electronic reporting, but that these costs will be offset 
with savings over time such that ultimately there will be an 
unquantified reduction in costs to the affected facilities.
2. 40 CFR Part 63, Subpart EEEEEE
    With regard to the proposed electronic reporting requirements, 
which will eliminate paper-based manual processes, the EPA expects a 
small initial unquantified cost to transition to electronic reporting, 
but that these costs will be offset with savings over time such that 
ultimately there will be an unquantified reduction in costs to the 
affected facilities.

D. What are the economic impacts?

1. 40 CFR Part 63, Subpart QQQ
    The net present value of the estimated cost impacts of the proposed 
revisions to the Primary Copper Smelting NESHAP is $18.2 million, 
discounted at a 7 percent rate over an 8-year analytic time frame from 
2022 to 2029 in 2019 dollars. Using a 3 percent discount rate, the net 
present value of the estimated cost impacts is $19.6 million.
    As described previously in this preamble, the Agency estimates the 
new standards for anode refining fugitive emissions and mercury will 
result in annualized costs of about $2.3 million for the Freeport 
facility. Based on our research, the estimated annualized costs for 
Freeport are about 0.016 percent of the annual revenue of the 
facility's ultimate parent company in 2019. For the Asarco facility, 
the estimated annualized costs of the proposed rule (i.e., $95,000 in 
testing costs) were less than 0.01 percent of 2019 revenues for the 
facility's ultimate parent company. Financial data was not available 
for the individual facilities.
    We have data which estimates that the amount of copper produced by 
U.S. smelters was 563,000 metric tons in 2016 and 315,000 metric tons 
in 2020.\33\ This decrease may have been in part due to the fact that 
Asarco's smelting operation was shut down for the entire year of 2020 
and could have been further impacted by labor and supply issues related 
to COVID-19. We are not able to determine exactly how much the three 
U.S. facilities produced individually or the share of the domestic 
market they represent. Furthermore, we do not have the detailed 
information needed to determine what percentage of the copper consumed 
in the U.S. comes from these facilities as opposed to being imported, 
how much of the production of these facilities is exported, or what the 
market impacts would be.
---------------------------------------------------------------------------

    \33\ USGS National Minerals Information Center--Copper 
Statistics and Information available at: https://www.usgs.gov/centers/nmic/copper-statistics-and-information
---------------------------------------------------------------------------

    The economic impacts of this proposed rule were determined by 
comparing the annualized costs estimated for each facility to the 
annual revenues of the facility's ultimate parent company to obtain 
cost to sales ratios. This is EPA's typical method for determining 
economic impacts, because parent companies are assumed to be able to 
shift resources across their operations to address regulatory 
compliance needs. Since the estimated cost impacts for the facilities' 
ultimate parent companies are minimal, EPA anticipates there to be no 
significant economic impacts on the individual facilities due to the 
proposed revisions.
2. 40 CFR Part 63, Subpart EEEEEE
    There are no significant economic impacts anticipated due to the 
proposed revisions under 40 CFR part 63, subpart EEEEEE.

E. What are the benefits?

1. 40 CFR Part 63, Subpart QQQ
    As described above, the proposed amendments would result in 
significant reductions in emissions of HAP metals, especially lead and 
arsenic. The proposed amendments also revise the standards such that 
they apply at all times, which includes SSM periods. Furthermore, the 
proposed requirements to submit reports and test results electronically 
will improve monitoring, compliance, and implementation of the rule.
2. 40 CFR Part 63, Subpart EEEEEE
    The proposed amendments under 40 CFR part 63, subpart EEEEEE revise 
the standards such that they apply at all times, which includes SSM 
periods. Furthermore, the proposed requirements to submit reports and 
test results electronically will improve monitoring, compliance, and 
implementation of the rule.

VI. Request for Comments

    The EPA solicits comments on this proposed action. In addition to 
general comments on this proposed action, the Agency is also interested 
in additional data that may improve the emissions estimates, risk 
assessments, control and cost impacts analyses, and other analyses. The 
EPA is specifically interested in receiving any improvements to the 
data used in the site-specific emissions profiles used for risk 
modeling. Such data should include supporting documentation in 
sufficient detail to allow characterization of the quality and 
representativeness of the data or information. Section VII of this 
preamble provides more information on submitting data. The EPA is also 
specifically interested in receiving comments and data on the economic 
impacts of the proposed rule changes to individual facilities.

VII. Submitting Data Corrections

    The site-specific emissions profiles used in the source category 
risk and demographic analyses and instructions are available for 
download on the RTR website at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air. The data files include detailed information for each HAP 
emissions release point for the facilities in the source category.
    If you believe that the data are not representative or are 
inaccurate, please identify the data in question, provide your reason 
for concern, and provide any ``improved'' data that you have, if 
available. When you submit data, the Agency requests that you provide 
documentation of the basis for the revised values to support your 
suggested changes. To submit comments on the data downloaded from the 
RTR website, complete the following steps:
    1. Within this downloaded file, enter suggested revisions to the 
data fields appropriate for that information.

[[Page 1652]]

    2. Fill in the commenter information fields for each suggested 
revision (i.e., commenter name, commenter organization, commenter email 
address, commenter phone number, and revision comments).
    3. Gather documentation for any suggested emissions revisions 
(e.g., performance test reports, material balance calculations).
    4. Send the entire downloaded file with suggested revisions in 
Microsoft[supreg] Access format and all accompanying documentation to 
Docket ID No. EPA-HQ-OAR-2020-0430 (through the method described in the 
ADDRESSES section of this preamble).
    5. If you are providing comments on a single facility or multiple 
facilities, you need only submit one file for all facilities. The file 
should contain all suggested changes for all sources at that facility 
(or facilities). The Agency requests that all data revision comments be 
submitted in the form of updated Microsoft[supreg] Excel files that are 
generated by the Microsoft[supreg] Access file. These files are 
provided on the project website at https://www.epa.gov/stationary-sources-air-pollution/primary-copper-smelting-national-emissions-standards-hazardous-air.

VIII. Incorporation by Reference

    The EPA proposes to amend 40 CFR 63.14 to incorporate by reference 
for three VCS.
     ANSI/ASME PTC 19.10-1981, Flue and Exhaust Gas Analysis 
[Part 10, Instruments and Apparatus], issued August 31, 1981, IBR 
requested for 40 CFR 63.1450(a)(iii), (b)(iii), (d)(iii), and (e)(iii). 
This method is an approved alternative to EPA Method 3B manual portion 
only, not the instrumental portion. The applicable portion of this 
Performance Test Code is the wet chemical manual procedures, apparatus 
and calculations for quantitatively determining oxygen, carbon dioxide, 
carbon monoxide and nitrogen from stationary combustion sources.
     ASTM D7520-16, Standard Test Method for Determining the 
Opacity of a Plume in the Outdoor Ambient Atmosphere, approved April 1, 
2016, IBR requested for 40 CFR 63.1450(e)(1)(vii). This method is an 
acceptable alternative to the EPA's Method 9 under specific conditions 
stated in 40 CFR 63.1450(e)(1)(vii). This test method described the 
procedures to use the Digital Camera Opacity Techniques (DCOT) to 
obtain and interpret the digital images in determining and reporting 
plume opacity. It also describes procedures to certify the DCOT.
     ASTM D6784-02, (Reapproved 2008), Standard Test Method for 
Elemental, Oxidized, Particle-Bound and Total Mercury in Flue Gas 
Generated from Coal-Fired Stationary Sources (Ontario Hydro Method), 
Approved April 1, 2008. IBR requested for 40 CFR 63.1450(d)(1)(v). This 
method is an acceptable alternative to the EPA's Method 29 as a method 
for measuring mercury and applies to concentrations approximately from 
0.5 to 100 [mu]g/Nm \3\. This test method describes equipment and 
procedures for obtaining samples from effluent ducts and stacks, 
equipment and procedures for laboratory analysis, and procedures for 
calculating results.
    The ANSI/ASME document is available from the American Society of 
Mechanical Engineers (ASME) at http://www.asme.org; by mail at Two Park 
Avenue, New York, NY 10016-5990; or by telephone at (800) 843-2763. The 
ASTM documents are available from the American Society for Testing and 
Materials (ASTM) at https://www.astm.org; by mail at l00 Barr Harbor 
Drive, P.O. Box C700, West Conshohocken, PA 19428-2959; or by telephone 
at (610) 832-9500.

IX. 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 Order 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 OMB for review. Any changes made in response to OMB recommendations 
have been documented in the docket (Docket ID No. EPA-HQ-OAR-2020-
0430).

B. Paperwork Reduction Act (PRA)

1. 40 CFR Part 63, subpart QQQ
    The information collection activities in this proposed 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 1850.10. You can find a copy of the ICR in the 
docket for this rule, and it is briefly summarized here.
    The EPA is proposing amendments that require electronic reporting 
of results of performance tests and CEMS performance evaluations, 
fugitive dust plans and notification of compliance reports, remove the 
requirement to submit certain information related to the malfunction 
exemption, and impose other rule revisions that affect reporting and 
recordkeeping requirements for primary copper smelting facilities, such 
as requirements to submit new performance test reports and to maintain 
new operating parameter records to demonstrate compliance with new 
standards. This information would be collected to assure compliance 
with 40 CFR part 63, subpart QQQ.
    Respondents/affected entities: Owners or operators of primary 
copper smelting facilities.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart QQQ).
    Estimated number of respondents: Two (total).
    Frequency of response: Initial, semiannual, and annual.
    Total estimated burden: The annual recordkeeping and reporting 
burden for facilities to comply with all of the requirements in the 
NESHAP is estimated to be 5,500 hours (per year). Burden is defined at 
5 CFR 1320.3(b).
    Total estimated cost: The annual recordkeeping and reporting burden 
for facilities to comply with all of the requirements in the NESHAP is 
estimated to be $750,000 (per year), of which $130,000 is for this 
rule, and $620,000 is for the other costs related to continued 
compliance with the NESHAP. There are no annualized capital or 
operation & maintenance costs.
2. 40 CFR Part 63, Subpart EEEEEE
    The information collection activities in this proposed rule have 
been submitted for approval to OMB under the PRA. The ICR document that 
the EPA prepared has been assigned EPA ICR number 2240.07. You can find 
a copy of the ICR in the docket for this rule, and it is briefly 
summarized here.
    The EPA is proposing amendments that require electronic reporting 
of results of performance tests and CEMS performance evaluations and 
notification of compliance reports, remove the malfunction exemption, 
and impose other revisions that affect reporting and recordkeeping for 
primary copper smelting facilities. This information would be collected 
to assure compliance with 40 CFR part 63, subpart EEEEEE.
    Respondents/affected entities: Owners or operators of primary 
copper smelting facilities.
    Respondent's obligation to respond: Mandatory (40 CFR part 63, 
subpart EEEEEE).
    Estimated number of respondents: One (total).

[[Page 1653]]

    Frequency of response: Initial, semiannual, and quarterly.
    Total estimated burden: The annual recordkeeping and reporting 
burden for facilities to comply with all of the requirements in the 
NESHAP is estimated to be 9 hours (per year). Burden is defined at 5 
CFR 1320.3(b).
    Total estimated cost: The annual recordkeeping and reporting burden 
for facilities to comply with all of the requirements in the NESHAP is 
estimated to be $1,060 (per year). There are no 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.
    Submit your comments on the Agency's need for this information, the 
accuracy of the provided burden estimates, and any suggested methods 
for minimizing respondent burden to the EPA using the docket identified 
at the beginning of this rule. You may also send your ICR-related 
comments to OMB's Office of Information and Regulatory Affairs via 
email to [email protected], Attention: Desk Officer for the 
EPA. Since OMB is required to make a decision concerning the ICR 
between 30 and 60 days after receipt, OMB must receive comments no 
later than February 10, 2022. The EPA will respond to any ICR-related 
comments in the 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. Based on the 
Small Business Administration size category for this source category, 
no small entities are subject to this action.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no enforceable duty on any state, 
local, or tribal governments or the private sector.

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. Thus, Executive Order 13175 does not apply to 
this action. However, consistent with the EPA policy on coordination 
and consultation with Indian tribes, the EPA will offer government-to-
government consultation with tribes as requested.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks and 1 CFR Part 51

    This action is not subject to Executive Order 13045 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 sections III and IV of 
this preamble and further documented in the document titled Residual 
Risk Assessment for the Primary Copper Smelting Major Source Category 
in Support of the 2021 Risk and Technology Review Proposed Rule, which 
is available in the docket for this proposed rule (Docket ID No. EPA-
HQ-OAR-2020-0430).

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. As described in more details in 
sections IV.A and V.D of this preamble, new standards are proposed for 
40 CFR part 63, subpart QQQ to limit mercury emissions, and PM 
emissions from anode refining furnaces and process roof vents. The 
proposed limits would have minimal impacts on the affected facilities 
because they mostly already meet the limits. One facility will have to 
improve their capture and control systems, which they were already 
planning to do as referenced in a consent order with the state of 
Arizona.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking involves technical standards. Therefore, the EPA 
conducted searches for National Emission Standards for Hazardous Air 
Pollutants: Primary Copper Smelting Residual Risk and Technology Review 
and Primary Copper Smelting Area Source Technology Review through the 
Enhanced NSSN Database managed by the American National Standards 
Institute (ANSI). The Agency also contacted VCS organizations and 
accessed and searched their databases. Searches were conducted for the 
EPA Methods 1, 1A, 2, 2A, 2C, 2D, 2F, 2G, 3, 3A, 3B, 4, 5, 5B, 9, 17, 
22, 29, 30A, 30B of 40 CFR part 60, appendix A, and EPA Method 201A 
appendix M, 40 CFR part 51. No applicable VCS were identified for EPA 
Methods 1A, 2A, 2D, 2F, 2G, 5B, 5D, 22, 30A, 30B.
    During the search, if the title or abstract (if provided) of the 
VCS described technical sampling and analytical procedures that are 
similar to the EPA's reference method, the EPA considered it as a 
potential equivalent method. All potential standards were reviewed to 
determine the practicality of the VCS for this rule. This review 
requires significant method validation data which meets the 
requirements of the EPA Method 301 for accepting alternative methods or 
scientific, engineering and policy equivalence to procedures in the EPA 
reference methods. The EPA may reconsider determinations of 
impracticality when additional information is available for particular 
VCS.
    Three VCS were identified as an acceptable alternative to the EPA 
test methods for the purposes of this rule. The VCS ANSI/ASME PTC 19-
10-1981 Part 10 (2010), ``Flue and Exhaust Gas Analyses'' is an 
acceptable alternative to the EPA Method 3B manual portion only and not 
the instrumental portion. The ANSI/ASME PTC 19-10-1981 Part 10 (2010) 
method incorporates both manual and instrumental methodologies for the 
determination of O2 content. The manual method segment of the O2 
determination is performed through the absorption of O2. The VCS ASTM 
D7520-16 ``Standard Test Method for Determining the Opacity of a Plume 
in the Outdoor Ambient Atmosphere'' is an acceptable alternative to the 
EPA Method 9 with the following conditions:
    1. During the digital camera opacity technique (DCOT) certification 
procedure outlined in section 9.2 of ASTM D7520-16, you or the DCOT 
vendor must present the plumes in front of various backgrounds of color 
and contrast representing conditions anticipated during field use such 
as blue sky, trees, and mixed backgrounds (clouds and/or a sparse tree 
stand).
    2. You must also have standard operating procedures in place 
including daily or other frequency quality checks to ensure the 
equipment is within manufacturing specifications as

[[Page 1654]]

outlined in section 8.1 of ASTM D7520-16.
    3. You must follow the record keeping procedures outlined in Sec.  
63.10(b)(1) for the DCOT certification, compliance report, data sheets, 
and all raw unaltered JPEGs used for opacity and certification 
determination.
    4. You or the DCOT vendor must have a minimum of four (4) 
independent technology users apply the software to determine the 
visible opacity of the 300 certification plumes. For each set of 25 
plumes, the user may not exceed 15 percent opacity of anyone reading 
and the average error must not exceed 7.5 percent opacity.
    5. This approval does not provide or imply a certification or 
validation of any vendor's hardware or software. The onus to maintain 
and verify the certification and/or training of the DCOT camera, 
software and operator in accordance with ASTM D7520-16 and this letter 
is on the facility, DCOT operator, and DCOT vendor.
    The VCS ASTM D6784-02(2008) reapproved, ``Standard Test Method for 
Elemental, Oxidized, Particle-Bound and Total Mercury Gas Generated 
from Coal-Fired Stationary Sources (Ontario Hydro Method)'' is an 
acceptable alternative to the EPA Methods 101A and Method 29 (portion 
for mercury only) as a method for measuring mercury applies to 
concentrations approximately 0.5-100 [mu]g/Nm\3\. The ASTM D6784-02 
method is used to determine elemental, oxidized, particle-bound and 
total mercury emissions from coal-fired stationary sources with 
concentrations ranging from approximately 0.05 to 100 ug/dscm.
    The search identified 189 VCS that were potentially applicable for 
these rules in lieu of the EPA reference methods. After reviewing the 
available standards, the EPA determined that 199 candidate VCS (ASTM 
D3154-00 (2014), ASTM D3464-96 (2014), ASTM 3796-09 (2016), ISO 
10780:1994 (2016), ASME B133.9-1994 (2001), ISO 10396:(2007), ISO 
12039:2001(2012), ASTM D5835-95 (2013), ASTM D6522-11, CAN/CSA Z223.2-
M86 (R1999), ISO 9096:1992 (2003), ANSI/ASME PTC-38-1980 (1985), ASTM 
D3685/D3685M-98-13, CAN/CSA Z223.1-M1977, ISO 10397:1993, ASTM D6331 
(2014), EN13211:2001, CAN/CSA Z223.26-M1987) identified for measuring 
emissions of pollutants or their surrogates subject to emission 
standards in the rule would not be practical due to lack of 
equivalency, documentation, validation data and other important 
technical and policy considerations. Additional information for the VCS 
search and determinations can be found in the memorandum, Voluntary 
Consensus Standard Results for National Emission Standards for 
Hazardous Air Pollutants: Primary Copper Smelting Residual Risk and 
Technology Review and Primary Copper Smelting Area Source Technology 
Review, which is available in the docket for this action.
    Under 40 CFR 63.7(f) and 40 CFR 63.8(f) of subpart A of the General 
Provisions, a source may apply to the EPA to use alternative test 
methods or alternative monitoring requirements in place of any required 
testing methods, performance specifications or procedures in the final 
rule or any amendments.
    The EPA welcomes comments on this aspect of the proposed rulemaking 
and, specifically, invites the public to identify potentially 
applicable VCS and to explain why such standards should be used in this 
regulation.

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

    Executive Order 12898 (59 FR 7629, February 16, 1994) directs 
federal agencies, to the greatest extent practicable and permitted by 
law, to make environmental justice part of their mission by identifying 
and addressing, as appropriate, disproportionately high and adverse 
human health or environmental effects of their programs, policies, and 
activities on minority populations and low-income populations. The EPA 
believes that this proposed action would 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.
    The EPA defines environmental justice 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. 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.'' \34\ In implementing 
its environmental justice-related efforts, the Agency has expanded the 
concept of fair treatment to consider not only the distribution of 
burdens across all populations, but also the distribution of reductions 
in risk from EPA actions, when data allow.\35\ As described in section 
IV.B.7 of this action and shown in Table 3, EPA evaluated the 
demographic characteristics of communities located near the major 
source facilities and determined that elevated cancer risks associated 
with emissions from these facilities disproportionately affect Native 
American, Hispanic, Below Poverty Level and Over 25 without High School 
Diploma individuals living nearby. As part of its environmental justice 
analysis, EPA evaluated whether the proposed action for the Primary 
Copper Smelting Major Source Category would address the existing 
disproportionately high and adverse human health effect on these 
individuals and EPA further evaluated the projected distribution of 
reductions in risk resulting from the proposed action.
---------------------------------------------------------------------------

    \34\ U.S. EPA. Office of Environmental Justice Plan EJ 2014, 
September 2011. Available at https://nepis.epa.gov/Exe/ZyPDF.cgi/P100DFCQ.PDF?Dockey=P100DFCQ.PDF.
    For more information, see the EPA's Environmental Justice 
website, http://www.epa.gov/environmentaljustice/.
    \35\ U.S. EPA. June 2016. Technical Guidance for Assessing 
Environmental Justice in Regulatory Actions. Available at:
    https://www.epa.gov/sites/production/files/2016-06/documents/ejtg_5_6_16_v5.1.pdf.
---------------------------------------------------------------------------

    This proposed action is projected to reduce the number of 
individuals in these groups who live in proximity of the Freeport 
facility that have risk equal to or greater than 1-in-1 million. EPA 
estimates that there are approximately 24,412 people within 50 km of 
the Freeport facility with risk equal to or greater than 1-in-1 million 
(prior to controls); an estimated 6,835 of these people are Native 
American, 7,812 are Hispanic or Latino, and 6,591 are individuals below 
the poverty level. However, as described in section IV.B, we also 
estimate that no person has an increased cancer risk greater than 90-
in-1 million. This proposed action would reduce the number of Native 
American individuals with cancer risk equal to or above 1-in-1 million 
to an estimated 2,724, would reduce the number of Hispanic or Latino 
individuals with cancer risk equal to or above 1-in-1 million to an 
estimated 7,198, and would reduce the number of individuals below the 
poverty level with cancer risk equal to or above 1-in-1 million to an 
estimated 4,475. There would be no reduction in the number of 
individuals with modeled cancer risk greater than 1-in-1 million at 
Asarco, since EPA estimates the proposed limit will

[[Page 1655]]

achieve no quantified emissions reductions for Asarco.
    Based upon these reductions, approximately 20,566 people within a 
50-km radius of the modeled facilities would be exposed to a cancer 
risk greater than or equal to 1-in-1 million as a result of emissions 
from Primary Copper Smelting post-control source category operations. 
This represents a 21 percent reduction in the total population at risk 
when compared to actual emissions without controls. Furthermore, as 
described in section IV.C.3, after implementation of this proposed 
action, the maximum modeled lifetime increased cancer risk due to HAP 
emissions from the two major source primary copper smelting facilities 
for any individual is estimated to be 60-in-1 million. The demographic 
analysis based on post-control emissions is provided in the report Risk 
and Technology Review--Analysis of Demographic Factors for Populations 
Living Near Primary Copper Smelting Post-Control Source Category 
Operations, available in docket EPA-HQ-OAR-2020-0430, part of the rules 
and guidelines for 40 CFR part 63, subpart QQQ).
    The above risk-based demographic report indicates that for the 
major source category as a whole there will be a reduction in average 
cancer risk for each demographic group within a 50 kilometer radius of 
the modeled facilities as a result of proposed standards to reduce 
emissions at the Freeport facility, specifically: Hispanic or Latino 
(4-in-1 million to 3-in-1 million); Native American (2-in-1 million to 
1-in-1 million); African American (10-in-1 million to 5-in-1 million); 
Other and Multiracial (5-in-1 million to 3-in-1 million); people living 
below the poverty level (4-in-1 million to 2-in-1 million); people 25 
years old and older without a high school diploma (4-in-1 million to 2-
in-1 million); and people living in linguistic isolation (4-in-1 
million to 2-in-1 million). For the total population exposed to 
emissions from the major source category, average cancer risk would be 
reduced from 4-in-1 million to 2-in-1 million.
    This action's health and risk assessments and related decisions are 
described in section IV of this action. The detailed documentation for 
these assessments is contained in the Residual Risk Assessment for the 
Primary Copper Smelting Major Source Category in Support of the 2021 
Risk and Technology Review Proposed Rule. The methodology and the 
results of the baseline and post-control demographic analyses are 
presented in the technical reports, Risk and Technology Review--
Analysis of Demographic Factors for Populations Living Near Primary 
Copper Smelting Source Category Operations and Risk and Technology 
Review--Analysis of Demographic Factors For Populations Living Near 
Primary Copper Smelting Post-Control Source Category Operations, 
respectively. These reports are available in the docket for this 
proposed rule (Docket ID No. EPA-HQ-OAR-2020-0430).

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous 
substances, Incorporation by reference, Reporting and recordkeeping 
requirements.

Michael S. Regan,
Administrator.
[FR Doc. 2021-28273 Filed 1-10-22; 8:45 am]
BILLING CODE 6560-50-P