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Proposed Rule2025-10992

National Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating Units

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Published

June 17, 2025

Issuing agencies

Environmental Protection Agency

Abstract

In this action, the U.S. Environmental Protection Agency (EPA) is proposing to repeal specific amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Coal- and Oil-Fired Electric Utility Steam Generating Units (EGUs), commonly referred to as the Mercury and Air Toxics Standards (MATS), that were promulgated on May 7, 2024. The amendments that the EPA is proposing to repeal include the revised filterable particulate matter (fPM) emission standard, which serves as a surrogate for non-mercury hazardous air pollutant (HAP) metals for existing coal-fired EGUs; the revised fPM emission standard compliance demonstration requirements; and the revised mercury (Hg) emission standard for lignite-fired EGUs.

Full Text

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<title>Federal Register, Volume 90 Issue 115 (Tuesday, June 17, 2025)</title>
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[Federal Register Volume 90, Number 115 (Tuesday, June 17, 2025)]
[Proposed Rules]
[Pages 25535-25546]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-10992]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2018-0794; FRL-6716.4-01-OAR]
RIN 2060-AW68

National Emission Standards for Hazardous Air Pollutants: Coal-
and Oil-Fired Electric Utility Steam Generating Units

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: In this action, the U.S. Environmental Protection Agency (EPA)
is proposing to repeal specific amendments to the National Emission
Standards for Hazardous Air Pollutants (NESHAP) for Coal- and Oil-Fired
Electric Utility Steam Generating Units (EGUs), commonly referred to as
the Mercury and Air Toxics Standards (MATS), that were promulgated on
May 7, 2024. The amendments that the EPA is proposing to repeal include
the revised filterable particulate matter (fPM) emission standard,
which serves as a surrogate for non-mercury hazardous air pollutant
(HAP) metals for existing coal-fired EGUs; the revised fPM emission
standard compliance demonstration requirements; and the revised mercury
(Hg) emission standard for lignite-fired EGUs.

DATES:
Comments. Comments must be received on or before August 11, 2025.
Comments on the information collection provisions of the proposed rule
under the Paperwork Reduction Act (PRA) must be received by the Office
of Management and Budget's Office of Information and Regulatory Affairs
(OMB-OIRA) on or before July 17, 2025. For specific instructions,
please refer to the PRA information in the ``Statutory and Executive
Order Reviews'' section of this preamble.
Public hearing: The EPA will hold a public hearing on July 10,
2025. Please refer to the SUPPLEMENTARY INFORMATION section for
information on registering for the public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-HQ-
OAR-2018-0794 by any of the following methods:
<bullet> Federal eRulemaking Portal: <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>
(our preferred method). Follow the online instructions for submitting
comments.
<bullet> Email: <a href="/cdn-cgi/l/email-protection#39581458575d144b145d565a525c4d795c4958175e564f">[email&#160;protected]</a>. Include Docket ID No. EPA-
HQ-OAR-2018-0794 in the subject line of the message.
<bullet> Mail: U.S. Environmental Protection Agency, EPA Docket
Center, Docket ID No. EPA-HQ-OAR-2018-0794, Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
<bullet> 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 <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, 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.

FOR FURTHER INFORMATION CONTACT: For questions about this proposed
action, contact Sarah Benish, Sector Policies and Programs Division
(D243-01), Office of Air Quality Planning and Standards, U.S.
Environmental Protection Agency, P.O. Box 12055, Research Triangle
Park, North Carolina 27711; telephone number: (919) 541-5620; and email
address: <a href="/cdn-cgi/l/email-protection#86e4e3e8eff5eea8f5e7f4e7eec6e3f6e7a8e1e9f0">[email&#160;protected]</a>. Individuals who are deaf or hard of
hearing, as well as individuals who have speech or communication
disabilities may use a telecommunications relay service. To learn more
about how to make an accessible telephone call to any of the telephone
numbers shown in this document, please visit the web page for the relay
service of the Federal Communications Commission at <a href="https://www.fcc.gov/trs">https://www.fcc.gov/trs</a>, and a list of relay services is available on their
directory page at <a href="https://www.fcc.gov/general/trs-state-and-territories">https://www.fcc.gov/general/trs-state-and-territories</a>.

SUPPLEMENTARY INFORMATION:
Participation in virtual public hearing. The public hearing will be
held via virtual platform on July 10, 2025. The hearing will convene at
11 a.m. Eastern Time (ET) and will conclude at 7 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.

[[Page 25536]]

The EPA will begin pre-registering speakers for the hearing no
later than 1 business day following publication of this document in the
Federal Register. To register to speak at the virtual hearing, please
use the online registration form available at <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a> or
contact the public hearing team at (888) 372-8699 or by email at
<a href="/cdn-cgi/l/email-protection#6536353521151007090c060d0004170c0b02250015044b020a13">[email&#160;protected]</a>. The last day to pre-register to speak at the
hearing will be June 29, 2025. Prior to the hearing, the EPA will post
a general agenda that will list pre-registered speakers at: <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>.
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 4 minutes to provide oral testimony. The
EPA encourages commenters to submit a copy of their oral testimony as
written comments electronically 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 <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>. 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
<a href="/cdn-cgi/l/email-protection#5f0c0f0f1b2f2a3d33363c373a3e2d3631381f3a2f3e71383029">[email&#160;protected]</a> 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 a special accommodation such as audio description,
please pre-register for the hearing with the public hearing team and
describe your needs by June 24, 2025. The EPA may not be able to
arrange accommodations without advance notice.
Docket. The EPA has established a docket for this rulemaking under
Docket ID No. EPA-HQ-OAR-2018-0794.\1\ All documents in the docket are
listed in <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>. 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. Except for such material, publicly available docket materials are
available electronically in <a href="http://Regulations.gov">Regulations.gov</a>.
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\1\ As explained in a memorandum to the docket, the docket for
this action includes the documents and information, in whatever
form, in Docket ID Nos. EPA-HQ-OAR-2009-0234 (National Emission
Standards for Hazardous Air Pollutants for Coal- and Oil-fired
Electric Utility Steam Generating Units), EPA-HQ-OAR-2002-0056
(National Emission Standards for Hazardous Air Pollutants for
Utility Air Toxics; Clean Air Mercury Rule (CAMR)), and Legacy
Docket ID No. A-92-55 (Electric Utility Hazardous Air Pollutant
Emission Study). See memorandum titled Incorporation by reference of
Docket Number EPA-HQ-OAR-2009-0234, Docket Number EPA-HQ-OAR-2002-
0056, and Docket Number A-92-55 into Docket Number EPA-HQ-OAR-2018-
0794 (Docket ID Item No. EPA-HQ-OAR-2018-0794-0005).
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Instructions. Direct your comments to Docket ID No. EPA-HQ-OAR-
2018-0794. 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 <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, 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 to <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>
any information that you consider to be CBI or other information whose
disclosure is restricted by statute. This type of information should be
submitted as discussed in the Submitting CBI section of this document.
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 <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
The <a href="https://www.regulations.gov/">https://www.regulations.gov/</a> 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
<a href="https://www.regulations.gov/">https://www.regulations.gov/</a>, 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 <a href="https://www.epa.gov/dockets">https://www.epa.gov/dockets</a>.
Throughout this proposal, the EPA is soliciting comment on numerous
aspects of the proposed rule. The EPA has indexed each comment
solicitation with an identifier (e.g., ``Question 1, Question 2, . . .)
to provide a consistent framework for effective and efficient provision
of comments. Accordingly, we ask that commenters include the
corresponding identifier when providing comments relevant to that
comment solicitation. We ask that commenters include the identifier in
either a heading, or within the text of each comment (e.g., ``In
response to Question 1, . . .'') to make clear which comment
solicitation is being addressed. We emphasize that we are not limiting
comment to these identified areas and encourage provision of any other
comments relevant to this proposal.
Submitting CBI. Do not submit information containing CBI to the EPA
through <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>. Clearly mark the part or all the
information that you claim to be CBI. For CBI information on any
digital storage media that you mail to the EPA, note the Docket ID No.,
mark the outside of the digital storage media as CBI, and 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 the Instructions section of this document. If you submit
any digital storage media that does not contain CBI, mark the outside
of the digital storage media clearly that it does

[[Page 25537]]

not contain CBI and note the Docket ID No. 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.
Our preferred method to receive CBI is for it to be transmitted
electronically using email attachments, File Transfer Protocol (FTP),
or other online file sharing services (e.g., Dropbox, OneDrive, Google
Drive). Electronic submissions must be transmitted directly to the
OAQPS CBI Office at the email address <a href="/cdn-cgi/l/email-protection#e48b85959497bb87868da4819485ca838b92">[email&#160;protected]</a>, and as
described above, should include clear CBI markings and note the Docket
ID No. If assistance is needed with submitting large electronic files
that exceed the file size limit for email attachments, or if you do not
have your own file sharing service, please email <a href="/cdn-cgi/l/email-protection#4b242a3a3b38142829220b2e3b2a652c243d">[email&#160;protected]</a> to
request a file transfer link. If sending CBI information through the
postal service, please send it to the following address: OAQPS Document
Control Officer (C404-02), OAQPS, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina 27711, Attention Docket ID No.
EPA-HQ-OAR-2018-0794. The mailed CBI material should be double wrapped
and clearly marked. Any CBI markings should not show through the outer
envelope.
Preamble acronyms and abbreviations. We use 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:

Btu British thermal units
CAA Clean Air Act
CEMS continuous emission monitoring system(s)
CFB circulating fluidized bed
CPMS continuous parametric monitoring system(s)
EAV equivalent annualized values
EGU electric utility steam generating unit
ESP electrostatic precipitator
FF fabric filter
FGD flue gas desulfurization
fPM filterable particulate matter
FR Federal Register
GWh gigawatt-hour
HAP hazardous air pollutant(s)
HCl hydrogen chloride
HF hydrogen fluoride
Hg mercury
HQ hazard quotient
ICR Information Collection Request
IGCC integrated gasification combined cycle
lb pounds
LEE low emitting EGU
MATS Mercury and Air Toxics Standards
MMBtu million British thermal units of heat input
MW megawatt
NAICS North American Industry Classification System
NESHAP national emission standards for hazardous air pollutants
OMB Office of Management and Budget
PM particulate matter
PM CEMS particulate matter continuous emission monitoring system(s)
PV present values
REL reference exposure level
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RIN Regulatory Information Number
RTR residual risk and technology review
SO2 sulfur dioxide
SO3 sulfur trioxide
TBtu trillion British thermal units of heat input
UMRA Unfunded Mandates Reform Act

Organization of this document. The information in this preamble is
organized as follows:

I. General Information
A. Executive Summary
B. Does this action apply to me?
C. Where can I get a copy of this document and other related
information?
II. Background
A. Summary of the 2020 Final Action
B. Summary of the 2024 Review of the 2020 Final Action
C. Summary of the Authority for This Action
III. Basis for Proposed Repeal of the 2024 Final Action
A. Reevaluation of the 2024 Final Action
B. Statutory Authority of CAA Section 112
IV. Request for Comments
V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51

I. General Information

A. Executive Summary

On May 7, 2024, the EPA finalized amendments to the MATS Rule (89
FR 38508) (hereinafter ``2024 Final Action''). On March 12, 2025, EPA
Administrator Zeldin announced that the Agency would undertake 31
deregulatory actions to Power the Great American Comeback.\2\
``Reconsideration of Mercury and Air Toxics Standards that improperly
targeted coal-fired power plants (MATS)'' was among the deregulatory
actions that were announced.
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\2\ <a href="https://www.epa.gov/newsreleases/epa-launches-biggest-deregulatory-action-us-history">https://www.epa.gov/newsreleases/epa-launches-biggest-deregulatory-action-us-history</a>.
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In this action, the EPA is proposing to repeal the following
amendments from the 2024 Final Action:
<bullet> The filterable particulate matter (fPM) emission standard
for existing coal-fired electric utility steam generating units (EGUs),
which the EPA revised from 0.030 pounds per million British thermal
units (lb/MMBtu) to 0.010 lb/MMBtu;
<bullet> The compliance demonstration requirement for the fPM
emission standard for all coal- and oil-fired EGUs, which the EPA
revised from allowing EGU owners and operators to choose between use of
quarterly stack testing, use of continuous parametric monitoring
systems (CPMS), or use of PM continuous emission monitoring systems
(CEMS) to only allowing use of PM CEMS; and
<bullet> The Hg emission standard for existing lignite-fired EGUs,
which the EPA revised from 4.0 pounds per trillion British thermal
units (lb/TBtu) to 1.2 lb/TBtu.
The EPA previously, in 2020, finalized the statutorily required
residual risk and technology review (RTR) for MATS (hereinafter ``2020
Final Action'', 85 FR 31286, May 22, 2020). The amendments in the 2024
Final Action were the result of the EPA's review of the 2020 Final
Action and were finalized under the Clean Air Act (CAA) section
112(d)(6) provisions governing technology reviews.
The EPA has reevaluated the 2024 Final Action and proposes to find
that the revisions of the emissions standards that were finalized in
the 2024 Final Action were not necessary as they impose large
compliance costs or raise potential technical feasibility concerns.
Specifically, the EPA proposes to find that the cost-effectiveness
values associated with the revised fPM emission standard (i.e., the
cost per mass of fPM or non-Hg HAP metal(s) reduced, e.g., $/ton) are
higher than cost-effectiveness values that the EPA has previously found
to not be cost effective in other technology reviews and related
actions under CAA section 112. The EPA also proposes to find that a
requirement to utilize PM CEMS for compliance demonstration is an
unnecessary expense for coal- and oil-fired EGUs and that the owners
and operators of such sources should

[[Page 25538]]

maintain the option to utilize other monitoring methods to demonstrate
compliance with the fPM emission standard. Finally, the EPA proposes to
find that the Agency failed to demonstrate that the revised Hg emission
standard for lignite-fired EGUs is achievable across the broad range of
boiler types and varying compositions of the different lignite fuels.
These proposed amendments are in accordance with Executive Order 14192,
``Unleashing Prosperity Through Deregulation'' (90 FR 9065, February 6,
2025), Executive Order 14154, ``Unleashing American Energy'' (90 FR
8353, January 29, 2025), and Executive Order 14261, ``Reinvigorating
America's Beautiful Clean Coal Industry and Amending Executive Order
14241'' (90 FR 15517, April 14, 2025), among other recent Presidential
actions.
The EPA estimates that this proposed action would result in total
cost savings of $1 billion at a 3 percent discount rate and $770
million at a 7 percent discount rate over the 2028 to 2037 timeframe,
with total annualized cost savings of $120 and $110 million per year,
respectively (in 2024 dollars). More information about the estimated
costs and benefits of the regulated pollutants of this proposed action
can be found in section V.A of this preamble.

B. Does this action apply to me?

Regulated entities. The source category that is the subject of this
action is coal- and oil-fired EGUs regulated by the NESHAP under 40 CFR
part 63, subpart UUUUU, commonly known as MATS. The North American
Industry Classification System (NAICS) codes for the coal- and oil-
fired EGU source category are 221112, 221122, and 921150. This list of
NAICS codes is not intended to be exhaustive, but rather to provide a
guide for readers regarding entities likely to be affected by the
proposed action for the source category listed. To determine whether
your facility is affected, you should examine the applicability
criteria in the appropriate NESHAP. If you have any questions regarding
the applicability of any aspect of this NESHAP, please contact the
appropriate person listed in the preceding FOR FURTHER INFORMATION
CONTACT section of this preamble.

C. 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 proposed action will also be available on the internet. Following
signature by the EPA Administrator, the EPA will post a copy of this
proposed action at: <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>. In accordance with 5 U.S.C.
553(b)(4), a brief summary of this rule may be found at <a href="https://www.regulations.gov">https://www.regulations.gov</a>, Docket ID No. EPA-HQ-OAR-2018-0794. Following
publication in the Federal Register, the EPA will post the Federal
Register version and key technical documents at this same website.
A memorandum showing the rule edits that would be necessary to
incorporate the changes to 40 CFR part 63, subpart UUUUU proposed in
this action is available in the docket (Docket ID No. EPA-HQ-OAR-2018-
0794). Following signature by the EPA Administrator, the EPA also will
post a copy of this document to <a href="https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards">https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards</a>.

II. Background

The EPA promulgated the NESHAP for Coal- and Oil-Fired EGUs,
commonly referred to as the Mercury and Air Toxics Standards or MATS,
on February 16, 2012 (2012 MATS Final Rule). The standards are codified
at 40 CFR part 63, subpart UUUUU. Coal- and oil-fired EGUs are
combustion units of more than 25 megawatts (MW) that serve a generator
that produces electricity for sale and are located at both major and
area sources of HAP emissions.\3\ For coal-fired EGUs, the 2012 MATS
Final Rule established standards to limit emissions of Hg, acid gas HAP
(e.g., hydrogen chloride (HCl), hydrogen fluoride (HF)), non-Hg HAP
metals (e.g., nickel, lead, chromium), and organic HAP (e.g.,
formaldehyde, dioxin/furan). Emission standards for HCl serve as a
surrogate for the acid gas HAP. For coal-fired EGUs with flue gas
desulfurization (FGD), an alternate standard for sulfur dioxide
(SO<INF>2</INF>) may be used as a surrogate for acid gas HAP if
SO<INF>2</INF> CEMS are installed and operational. Standards for fPM
serve as a surrogate for the non-Hg HAP metals, with total and
individual HAP metals standards provided as an alternative. Work
practice standards were established to limit formation and emissions of
organic HAP. For oil-fired EGUs, the 2012 MATS Final Rule established
standards to limit emissions of HCl and HF, total HAP metals (e.g., Hg,
nickel, lead), and organic HAP (e.g., formaldehyde, dioxin/furan).
Standards for fPM also serve as a surrogate for total HAP metals, with
standards for total and individual HAP metals provided as alternative
equivalent standards. Work practice standards limit formation and
emissions of organic HAP.
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\3\ A unit that cogenerates steam and electricity and supplies
more than one-third of its potential electric output capacity and
more than 25 MW electrical output to any utility power distribution
system for sale is also an electric utility steam generating unit.
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A. Summary of the 2020 Final Action

The 2020 Final Action included two separate elements. First, the
2020 Final Action included a finding that it is not ``appropriate and
necessary,'' pursuant to CAA section 112(n)(1)(A),\4\ to regulate coal-
and oil-fired EGUs under CAA section 112. Second, the EPA completed the
residual risk and technology review (RTR) of MATS. As part of the RTR,
and as required by CAA section 112(f)(2), the EPA conducted the
residual risk review (2020 Residual Risk Review) of MATS, 8 years after
promulgating the 2012 MATS Final Rule. The residual risk review
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. Also, as
part of the RTR, and pursuant to CAA section 112(d)(6), the EPA
conducted a technology review (2020 Technology Review) of MATS in the
2020 Final Action. The 2020 Technology Review focused on identifying
and evaluating developments in practices, processes, and control
technologies for the emission sources in the source category that
occurred since promulgation of the 2012 MATS Final Rule.
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\4\ Note the ``appropriate and necessary'' finding pursuant to
CAA section 112(n)(1)(A) is a separate statutory requirement from
the EPA's obligation to review and revise standards ``as necessary''
in conducting a technology review pursuant to CAA section 112(d)(6).
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The 2020 Residual Risk Review results, along with our decisions
regarding risk acceptability, ample margin of safety, and adverse
environmental effects, were presented in the 2020 Final Action. The
results of the risk assessment are provided briefly in table 1, and in
more detail in the document titled Residual Risk Assessment for the
Coal- and Oil-Fired EGU Source Category in Support of the 2020 Risk and
Technology Review Final Rule (risk document for the final rule),
available in the docket (Document ID No. EPA-HQ-OAR-2018-0794-4553).
The EPA found the residual risk due to emissions of air toxics to be
acceptable from this source category and determined that the 2012 MATS
Final Rule provided an ample margin of safety to protect public health
and prevent an adverse environmental effect. Therefore, in 2020, the
EPA did not finalize any revisions to the 2012 MATS Final Rule

[[Page 25539]]

based on our analyses conducted under CAA section 112(f)(2) in the 2020
Final Action.

Table 1--Coal- and Oil-Fired EGU Inhalation Risk Assessment Results in the 2020 Final Action
[85 FR 31286, May 22, 2020]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Maximum individual Population at Annual cancer Maximum chronic Maximum screening acute
cancer risk (in 1 increased risk of incidence (cases per noncancer TOSHI \3\ noncancer HQ \4\
million) \2\ cancer >=1-in-1 year) ---------------------------------------------------
------------------------ million ------------------------ Based on . . .
Based on . . . ------------------------ Based on . . . ------------------------
Number of facilities \1\ ------------------------ Based on . . . ------------------------
------------------------ Actual Allowable Based on actual emissions
Actual Allowable Actual Allowable Actual Allowable emissions emissions level
emissions emissions emissions emissions emissions emissions level level
level level level level level level
--------------------------------------------------------------------------------------------------------------------------------------------------------
322......................... 9 10 193,000 636,000 0.04 0.1 0.2 0.4 HQREL = 0.09 (arsenic)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis. At the time of the risk analysis there were an estimated 323 facilities in the Coal- and Oil-
Fired EGU source category; however, one facility is in Guam, which was beyond the geographic range of the model used to estimate risks. Therefore, the
Guam facility was not modeled and the emissions for that facility were not included in the assessment.
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\3\ Maximum target organ-specific hazard index (TOSHI). The target organ systems with the highest TOSHI for the source category are respiratory and
immunological.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of hazard quotient (HQ)
values. HQ values shown use the lowest available acute threshold value, which in most cases is the reference exposure level (REL). When an HQ exceeds
1, we also show the HQ using the next lowest available acute dose-response value.

The 2020 Final Action also presented results of the 2020 Technology
Review, which focused on identifying and evaluating developments in
practices, processes, and control technologies that occurred since
promulgation of the 2012 MATS Final Rule. Control technologies
typically used to minimize emissions of pollutants that have numeric
emission limits under the 2012 MATS Final Rule include electrostatic
precipitators (ESPs) and fabric filters (FFs) for control of fPM as a
surrogate for non-Hg HAP metals; wet scrubbers, dry scrubbers, and dry
sorbent injection for control of acid gases (SO<INF>2</INF>, HCl, and
HF); and activated carbon injection (ACI) and other Hg-specific
technologies for control of Hg. In the 2020 Technology Review, the EPA
did not identify any developments in practices, processes, or control
technologies and, thus, did not finalize any changes to emission
standards or other requirements in the 2020 Final Action. More
information concerning that technology review is in the memorandum
titled Technology Review for the Coal- and Oil-Fired EGU Source
Category, available in the docket (Document ID No. EPA-HQ-OAR-2018-
0794-0015).

B. Summary of the 2024 Review of the 2020 Final Action

Executive Order 13990, ``Protecting Public Health and the
Environment and Restoring Science to Tackle the Climate Crisis'' (86 FR
7037, January 25, 2021), instructed the EPA to review the 2020 Final
Action and to consider publishing a notice of proposed rulemaking
suspending, revising, or rescinding that action. The EPA reviewed the
finding in the 2020 Final Action that it was not appropriate and
necessary to regulate coal- and oil-fired EGUs under CAA section 112
and, on February 9, 2022, proposed to find that it is appropriate and
necessary to regulate coal- and oil-fired EGUs under CAA section 112
(87 FR 7624). The EPA finalized the affirmative finding on March 6,
2023 (88 FR 13956).
On April 24, 2023, the EPA proposed the results of the review of
the RTR from the 2020 Final Action (2023 Proposal).\5\ This included a
review of the 2020 residual risk assessment described in Docket ID No.
EPA-HQ-OAR-2018-0794-0014. In the 2023 Proposal, the EPA determined
that the results of the 2020 Residual Risk Review, as shown in table 1
of this preamble, which indicated low residual risk from the coal- and
oil-fired EGU source category, were confirmed. Further, the EPA
determined in the 2023 Proposal that the risk analysis conducted in
2020 was a rigorous and robust analytical review that was conducted
using approaches and methodologies that were consistent with those that
have been utilized in risk analyses and reviews that the EPA has
conducted for other industrial sectors. For that reason, in the 2023
Proposal, the EPA did not reopen the 2020 Residual Risk Review and did
not propose any changes to any emissions standards or other
requirements in response to the CAA section 112(f)(2) risk review.
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\5\ See 78 FR 24854, April 24, 2023.
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The EPA's 2023 review of the 2020 Technology Review included
evaluating the technology review described in Docket ID No. EPA-HQ-OAR-
2018-0794-0015 and focused on the identification of any developments in
practices, processes, and control technologies that have occurred since
the finalization of the 2012 MATS Final Rule and since publishing the
2020 Technology Review. Based on this review, the EPA concluded in the
2023 Proposal that revisions to certain standards were warranted. The
EPA proposed three changes resulting from the review of the 2020
Technology Review. First, the EPA proposed to revise the existing coal-
fired EGU fPM emissions standard, which is a surrogate for non-Hg HAP
metals, from 0.030 lb/MMBtu to 0.010 lb/MMBtu and proposed
corresponding reductions in the alternative emission standards for
total and individual non-Hg HAP metals. Second, the EPA proposed to
require that all coal- and oil-fired EGUs demonstrate compliance with
the applicable fPM emission standard by using PM CEMS. Third, the EPA
proposed to revise the Hg emission standard for lignite-fired EGUs from
4.0 lb/TBtu to 1.2 lb/TBtu with an alternative output-based standard of
0.013 lb/gigawatt-hour (GWh). All those proposed changes were
ultimately finalized in the 2024 Final Action.\6\
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\6\ In the 2024 Final Action, the EPA also finalized the removal
of the work practice standards of paragraph (2) of the definition of
``startup'' in 40 CFR 63.10042. See 89 FR 38550. The final rule
requires that all EGUs use the work practice standards in paragraph
(1) of the definition of ``startup'' in 40 CFR 63.10042, which was
already being used by all but a handful of affected EGUs. The
revision was not done as part of the CAA section 112(d)(6)
technology review, but, rather, in part in response to Chesapeake
Climate Action Network v. EPA, 952 F.3d 310 (D.C. Cir. 2020), where
the D.C. Circuit remanded the alternative ``startup'' work practice
standard in paragraph (2) to the EPA for reconsideration. The
compliance deadline for the changes to the ``startup'' definition
was January 2, 2025. The EPA is not reconsidering this aspect of the
2024 Final Action.

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[[Page 25540]]

C. Summary of the Authority for this Action

Executive Order 14154, ``Unleashing American Energy'' (90 FR 8353,
January 29, 2025), specified that it is the policy of the United States
to ``protect the United States's economic and national security and
military preparedness by ensuring that an abundant supply of reliable
energy is readily accessible in every State and territory of the
Nation'' and ``to ensure that all regulatory requirements related to
energy are grounded in clearly applicable law'' (among others). The
Executive order directed the heads of all agencies to review all
existing regulations to identify agency actions that impose an undue
burden on the identification, development, or use of domestic energy
resource, with particular attention to oil, natural gas, coal,
hydropower, biofuels, critical mineral, and nuclear energy resources.
Agencies were directed to suspend, revise, or rescind all agency
actions identified as unduly burdensome. Executive Order 14154 also
revoked Executive Order 13990.
On April 8, 2025, President Trump signed a Proclamation,
``Regulatory Relief for Certain Stationary Sources to Promote American
Energy'' (90 FR 16777, April 21, 2025). This Proclamation exempted
certain stationary sources, identified in Annex 1 of the Proclamation,
from compliance with the 2024 Final Action. The President's exemption
is for a period of 2 years beyond the 2024 Final Action's compliance
date (i.e., for the period beginning July 8, 2027, and concluding July
8, 2029). Sources identified in Annex 1 will remain subject to the 2012
MATS Final Rule during the 2-year extension period. A copy of the
Presidential Proclamation and Annex 1 are available in the rulemaking
docket.
In response to these and other recent Presidential Actions,\7\ the
EPA has undertaken a review of the 2024 Final Action. In this action,
the EPA is proposing to reconsider and repeal amendments from the 2024
Final Action based on its review of the 2024 Final Action pursuant to
the EPA's statutory authority under CAA section 112 and the EPA's
authority to reconsider previous decisions taken under that authority
to the extent permitted by law and supported by a reasoned explanation.
FDA v. Wages & White Lion Invs., L.L.C., 145 S. Ct. 898, 917 (2025);
FCC v. Fox Television Stations, Inc., 556 U.S. 502, 515 (2009); see
also Motor Vehicle Mfrs. Ass'n v. State Farm Mutual Auto Ins. Co., 463
U.S. 29, 42 (1983). The basis for the EPA's review of the 2024 Final
Action and the results of that review are presented in the next
section.
---------------------------------------------------------------------------

\7\ Executive Order 14179, ``Removing Barriers to American
Leadership in Artificial Intelligence'' (90 FR 8741, January 31,
2025); Executive Order 14192, ``Unleashing Prosperity Through
Deregulation'' (90 FR 9065, February 6, 2025); Executive Order
14262, ``Strengthening the Reliability and Security of the United
States Electric Grid'' (90 FR 15521, April 14, 2025); Executive
Order 14261, ``Reinvigorating America's Beautiful Clean Coal
Industry and Amending Executive Order 14241'' (90 FR 15517, April
14, 2025); Executive Order 14270, ``Zero-based Regulatory Budgeting
to Unleash American Energy'' (90 FR 15643, April 15, 2025).
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III. Basis for Proposed Repeal of the 2024 Final Action

A. Reevaluation of the 2024 Final Action

The EPA's ability to revisit existing regulations under CAA section
112 is well-grounded in law. Specifically, the EPA has authority to
reconsider, repeal, or revise past decisions to the extent permitted by
law so long as the Agency provides a reasoned explanation. See, e.g.,
Motor Vehicle Mfrs. Ass'n, 463 U.S. at 42 (``[R]egulatory agencies do
not establish rules of conduct to last forever [and] an agency must be
given able latitude to adapt their rules and policies to . . . changing
circumstances.''); see also Clean Water Action v. EPA, 936 F.3d 308,
313 (5th Cir. 2019) (``EPA correctly surmised that, in addition to its
statutory authority to revise rules . . . administrative agencies
possess the inherent authority to revise previously-promulgated rules,
so long as they follow the proper administrative requirements and
provide a reasoned basis for the agency decision.''). This is true
when, as is the case here, an agency reviews a prior decision to
reconsider a regulation after a change in administration. Nat'l Ass'n
of Home Builders v. EPA, 682 F.3d 1032, 1038, 1043 (D.C. Cir. 2012)
(explaining that an agency's ``reevaluation of which policy would be
better in light of the facts'' is ``well within'' its discretion and
that a change in administration is a ``perfectly reasonable basis for
an executive agency's reappraisal of the costs and benefits of its
programs and regulations'' (internal quotation marks omitted)). When
permitted by the statutory scheme, ``[a]gencies obviously have broad
discretion to reconsider a regulation at any time.'' Clean Air Council
v. Pruitt, 862 F.3d 1, 8-9 (D.C. Cir. 2017).
The EPA presents its proposed review of the amendments from the
2024 Final Action below. Section III.A.1 presents the EPA's proposed
review of the fPM standard for coal-fired EGUs, and the proposed review
of the fPM compliance demonstration requirements is provided in section
III.A.2. Section III.A.3 presents the EPA's proposed review of the Hg
standard for lignite-fired EGUs. The EPA solicits comment on all
aspects of these proposed reviews.
1. Filterable PM Emission Standard for Coal-Fired EGUs
In the 2024 Final Action, the EPA finalized a more stringent fPM
emission standard, which serves as a surrogate for the non-Hg HAP
metals. The fPM standard was lowered from 0.030 lb/MMBtu to 0.010 lb/
MMBtu for all existing coal-fired EGUs. The 2024 Final Action also
proportionally lowered the individual and total non-Hg HAP metal
emission limits. Filterable PM was chosen as a surrogate for non-Hg HAP
metals in the 2012 MATS Final Rule because non-Hg HAP metals are
predominantly a component of the filterable fraction of total PM (which
is composed of a filterable and condensable fraction) and control of
fPM results in a co-reduction of non-Hg HAP metals.\8\ Additionally,
not all fuels emit the same type and amount of non-Hg HAP metals, but
most generally emit fPM that includes some amount and combination of
all the non-Hg HAP metals. Finally, using fPM as a surrogate eliminates
the cost of performance testing to demonstrate compliance with numerous
standards for individual non-Hg HAP metals (Docket ID No. EPA-HQ-OAR-
2009-0234).
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\8\ Selenium may be present in the filterable or the condensable
fraction as the acid gas, SeO<INF>2</INF>.
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In the 2024 Final Action, the EPA found there were developments in
practices, processes, and control technologies to reduce fPM emissions,
that the costs to comply with the more stringent fPM standard based on
these developments were reasonable, and that the revised standard
appropriately balanced the EPA's obligation under CAA section 112 to
achieve the maximum degree of emission reductions considering statutory
factors. As in previous CAA section 112 rulemakings, the EPA considered
costs in many ways, including cost effectiveness, the total capital
costs of proposed measures, annual costs, and costs compared to total
revenues. In addition, in the 2024 Final Action, the EPA found most
existing coal-fired EGUs were reporting fPM levels that were well below
the previous 0.030 lb/MMBtu emission limit \9\ and that the fleet
achieved these performance levels at lower costs than assumed during
promulgation of the

[[Page 25541]]

2012 MATS Final Rule fPM emission limit.
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\9\ For instance, the median fPM rate of the 296 coal-fired EGUs
assessed in the 2024 Final Action was 0.004 lb/MMBtu, or 60 percent
below the revised fPM limit of 0.010 lb/MMBtu (89 FR 38522, May 7,
2024).
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In this action, the EPA is proposing to repeal lowering the fPM
standard to 0.010 lb/MMBtu for coal-fired EGUs, as well as the
proportional lowering of the total and individual non-Hg HAP metal
limits because of the high costs of the revised standard, both in terms
of cost effectiveness, a common metric the EPA considers in CAA section
112(d)(6) technology reviews, and total costs. As the EPA noted in the
2024 Final Action, the EPA considers costs in various ways, depending
on the rule and affected sector. For example, the EPA has considered,
in previous CAA section 112 rulemakings, cost effectiveness, the total
capital costs of measures, annual costs, and the costs compared to
total revenues (e.g., cost-to-revenue ratios). As noted in the 2024
Final Action, the cost effectiveness of the revised fPM standard was
significantly higher than the cost-effectiveness ratios the EPA has
rejected in the past in technology reviews conducted under CAA section
112(d)(6) for other industries (89 FR 38533-34). The cost effectiveness
of the revised fPM standard was also an order of magnitude higher than
cost-effectiveness ratios that the EPA has accepted for fPM emissions
in other industries in other CAA section 112(d)(6) reviews. The EPA now
proposes to find that the costs for the power sector to achieve the
revised standard are too high, such that the revised standard is not
necessary under CAA section 112(d)(6).
In the 2024 Final Action, the EPA found the cost-effectiveness
estimate for EGUs reporting average fPM rates above the final fPM
emission limit of 0.010 lb/MMBtu was $10.5 million per ton of non-Hg
HAP metals and $34,500/ton of fPM.\10\ In response to the 2023
Proposal, commenters provided examples of previous rulemakings where
the EPA found controls to be not cost effective:
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\10\ Cost-effectiveness values reported in 2019 dollars.
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<bullet> In the Petroleum Refinery Sector technology review,\11\
the EPA declined to revise the fPM emission limit for existing fluid
catalytic cracking units after finding that it would cost $10 million
per ton of total non-Hg HAP metals reduced, which the EPA found was not
cost effective.
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\11\ Petroleum Refinery Sector Risk and Technology Review and
New Source Performance Standards, 80 FR 75178, 75201 (December 1,
2015).
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<bullet> In the Integrated Iron and Steel Manufacturing Facilities
technology review,\12\ the EPA declined to revise the non-Hg HAP metals
limit after finding that upgrading all fume/flame suppressants at blast
furnaces to baghouses would cost $7 million per ton of non-Hg HAP
metals reduced, which the EPA determined was not cost effective.
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\12\ National Emission Standards for Hazardous Air Pollutants:
Integrated Iron and Steel Manufacturing Facilities Residual Risk and
Technology Review, 85 FR 42074, 42088 (July 13, 2020).
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The high value of the cost effectiveness of the revised fPM limit
as compared to other NESHAP rulemakings is further illustrated by the
significant costs to certain facilities, which carried cost-
effectiveness values far exceeding the fleet average that the EPA
estimated for the revised fPM standard. For example, the Colstrip Power
Plant, a two-unit 1,500 MW subbituminous-fired power plant located in
Colstrip, Montana, was the only facility unable to meet the lower fPM
standard with existing controls based on the EPA's analysis. The EPA
projected that each unit at the Colstrip facility would need to install
a new FF to comply with the revised fPM standard. Based on the EPA's
estimate, the units at this facility accounted for almost half of the
2024 Final Action's total compliance costs, which the EPA estimated
would result in a cost-effectiveness ratio exceeding $16 million per
ton of non-Hg HAP metals removed at the Colstrip facility. By
comparison, in the Taconite Iron Ore Processing technology review,\13\
the EPA declined to revise the non-Hg HAP metals limit after finding
that installing wet scrubbers would cost $16 million per ton of non-Hg
HAP metals reduced, which the EPA concluded was not cost effective.
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\13\ National Emission Standards for Hazardous Air Pollutants:
Taconite Iron Ore Processing Residual Risk and Technology Review, 85
FR 45476, 45483 (July 28, 2020).
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Upon reconsideration, the EPA is proposing to repeal the more
stringent fPM standard and corresponding total and individual HAP metal
standards that were promulgated in the 2024 Final Action because the
cost effectiveness of the revised standard is inconsistent with the
EPA's prior technology review determinations. The EPA recognized
differences between the power sector and the other industries regulated
in the above-mentioned technology reviews in the 2024 Final Action and
determined that despite the high cost-effectiveness ratio, the revised
standards were still cost reasonable for the industry. The EPA is now
reconsidering that judgment and proposes to find that despite
developments recognized in the 2024 Final Action, the costs for the
power sector to achieve the revised standard are too high, such that
the revised standard is not necessary under CAA section 112(d)(6). If
finalized, the fPM and corresponding total and individual HAP metal
emission standards would revert to the standards that were promulgated
in the 2012 MATS Final Rule (e.g., 0.030 lb/MMBtu for fPM). The EPA
solicits comment on the rationale that the cost effectiveness of the
revised fPM standard is inconsistent with the Agency's prior CAA
section 112(d)(6) technology review determinations (Question #1).
Additionally, the EPA requests comment if there are other cost-
effective and achievable alternative standards based on developments in
practices, processes, and control technologies that we should consider
instead of repealing the 0.010 lb/MMBtu fPM standard for existing coal-
fired EGUs (Question #2).
2. Required Compliance Demonstration for the Filterable PM Emission
Standard
The 2012 MATS Final Rule specified that EGU owners and operators
could choose either quarterly stack testing, PM CPMS, or PM CEMS, to
demonstrate compliance with the fPM emission standard. All three
options were determined to be appropriate and sufficient for
demonstrating compliance with the fPM emission standard. The EPA's
review of MATS compliance reporting for the 2023 Proposal showed that
the owners and operators of approximately one-third of coal-fired EGUs
were using PM CEMS for compliance demonstration purposes (88 FR 24872).
In the 2023 Proposal, the EPA stated that the costs for PM CEMS had
decreased compared to the costs estimated in the 2012 MATS Final Rule.
In addition, the revised fPM limit of 0.010 lb/MMBtu for coal-fired
units would have required longer duration runs for EPA Method 5 stack
testing and may have required the use of EPA Method 5I, which would
have increased the costs for quarterly stack testing, making the stack
testing costs commensurate with the reduced costs for PM CEMS (88 FR
24873). The EPA also argued in the 2023 Proposal and 2024 Final Action
that PM CEMS provide increased transparency and access to emissions
data, which was an unquantifiable benefit to operators of affected
sources and to the public. In the 2024 Final Action, the EPA stated
that information provided by public commenters indicated that the
average annual cost for quarterly stack testing is about $12,000 less
than the equivalent uniform annual cost for PM CEMS, but the benefits
of emissions transparency and access to emissions data outweighed the
cost difference between

[[Page 25542]]

quarterly stack testing and PM CEMS (89 FR 38536-38537).
As discussed in section III.A.1, the EPA is proposing to repeal the
more stringent fPM emission standard. If this change to the fPM
standard is finalized, the EPA's conclusion in the 2023 Proposal and
2024 Final Action that the costs for PM CEMS are commensurate with the
costs for stack testing would no longer apply because longer duration
runs that increase stack testing costs would no longer be necessary.
Pursuant to CAA section 112(d)(6), the EPA may consider cost in
deciding whether to revise the requirements. Further, the EPA finds
additional authority to allow multiple compliance demonstration options
under CAA section 114(a)(1)(C), which allows that the EPA may require a
facility that ``may have information necessary for the purposes set
forth in this subsection, or who is subject to any requirement of this
chapter'' to ``install, use, and maintain such monitoring equipment''
on a ``one-time, periodic or continuous basis.''
The 2024 Final Action requirement to use PM CEMS to demonstrate
compliance meant that up to two-thirds of EGU owners and operators
would face higher compliance costs than they have previously incurred
when allowed to use quarterly stack testing or PM CPMS. As shown in
more detail in the regulatory impact analysis (RIA), the EPA estimates
a cost savings of $2.8 million per year related to the proposed repeal
of the PM CEMS requirement. While the EPA noted in the 2023 Proposal
that the use of PM CEMS would allow for more efficient pollutant
abatement and more transparency of EGU emissions, the EPA no longer
believes that those advantages outweigh the increased cost of PM CEMS
compared to the two other compliance options (i.e., PM CPMS and
quarterly stack testing) that were determined to be appropriate for
demonstrating compliance with the fPM emission standard in the 2012
MATS Final Rule. The EPA noted in the 2024 Final Action that CEMS
enable power plant operators to quickly identify and correct problems
with air pollution control devices (89 FR 38536). However, there are
other ways that owners and operators can become aware of air pollution
control malfunctions without employing PM CEMS. For example, operators
at EGUs with an ESP can track opacity, secondary corona power,
secondary voltage (i.e., the voltage across the electrodes), and
secondary current (i.e., the current to the electrodes) to ensure
proper functionality.\14\ For EGUs with FFs, bag leak detection systems
(BLDS) and parameters like pressure differential (i.e., pressure drop),
inlet temperature, temperature differential, exhaust gas flow rate,
cleaning mechanism operation, and fan current can serve as reliable
indicators.\15\ As noted earlier and in the 2024 Final Action, a large
majority of sources have reported measured compliance data showing fPM
emissions that are well below the previous fPM standard of 0.030 lb/
MMBtu, which further illustrates that the various options for
demonstrating compliance with the fPM standards have been appropriate
and effective. Additionally, all fPM compliance data can be accessed by
the public via the EPA's Web Factor Information Retrieval System
(WebFIRE),\16\ which maintains the availability and transparency of fPM
emissions. Therefore, the EPA proposes to repeal the requirement to use
PM CEMS for demonstrating compliance with the fPM emission standard, as
well as the adjusted QA criteria,\17\ and to return to the previous
requirement that allowed owners and operators to demonstrate compliance
using either quarterly stack testing, PM CPMS, or PM CEMS. This
provides greater flexibility to owners and operators and reduces the
compliance burden, while still assuring compliance with the fPM
emission standard. The EPA solicits comment on the rationale that
higher costs for approximately two-thirds of EGU owners and operators,
availability of other air pollution control performance indicators that
can inform operators of malfunctions, and the adequacy of current
compliance options support repealing the requirement that all coal- and
oil-fired EGUs must use PM CEMS (Question #3).
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\14\ See <a href="https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-electrostatic-precipitators">https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-electrostatic-precipitators</a>.
\15\ See <a href="https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-fabric-filters">https://www.epa.gov/air-emissions-monitoring-knowledge-base/monitoring-control-technique-fabric-filters</a>.
\16\ See <a href="https://cfpub.epa.gov/webfire">https://cfpub.epa.gov/webfire</a>.
\17\ New PM CEMS installations must follow Performance
Specification 11 (PS-11), which requires the development of a site-
specific correlation curve to relate PM CEMS readings to the PM
reference method values. Emission standards are used to determine
the acceptable tolerance interval when correlating PM CEMS. In the
2024 Final Action, the EPA instructed the use of 0.015 lb/MMBtu,
instead of the finalized more stringent limit of 0.010 lb/MMBtu,
when developing PM CEMS correlations to ease difficulties
correlating PM CEMS (89 FR 38535, May 7, 2024).
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The EPA also proposes to reinstate the low emitting EGU (LEE)
program for fPM and non-Hg HAP metals, which reduces the stack testing
frequency for sources that have demonstrated that their emissions are
less than 50 percent of the corresponding emission limit for 3
consecutive years. Sources that had previously demonstrated that they
qualify for LEE status would not have to re-demonstrate that
qualification. In the 2024 Final Action, the EPA found that the
optional LEE program was ``superfluous'' due to the PM CEMS requirement
and the revised fPM emission standard (89 FR 38510, May 7, 2025).
However, as the EPA is proposing to repeal these requirements,
reinstating the LEE program for fPM and non-Hg HAP metals would further
reduce the costs associated with stack testing for sources that opt-in,
while still assuring compliance with the emission standard.\18\ The EPA
solicits comment on whether the LEE program for fPM and non-Hg metals
should be reinstated (Question #4).
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\18\ Note that the LEE provisions ensure emissions are
minimized. For example, EGUs equipped with a main stack and a bypass
stack or bypass duct configuration that allows the effluent to
bypass any pollutant control device are not allowed to pursue the
LEE option under 40 CFR 63.10000(c). Furthermore, under 40 CFR
63.10000(c)(1)(i)(D), EGUs claiming LEE status may bypass a control
device during emergency periods for no more than 2 percent of the
EGU's annual operating hours.
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Finally, the EPA also proposes to retain the updated fPM
measurement requirements of allowing either an increased minimum volume
per run or the collection of a minimum mass per run.\19\ As stated
earlier in this preamble, a large majority of sources have reported
measured compliance data showing fPM emissions well below the previous
0.030 lb/MMBtu fPM standard. It is important that a sufficient quantity
of fPM be collected during these fPM test runs to allow for accurate
measurement of emissions, especially when the testing is being
conducted to correlate or certify a PM CEMS. The EPA believes that
retaining the additional option of sample mass would reduce measurement
uncertainty and may reduce test run durations and, therefore, reduce
fPM testing costs. The EPA solicits comment on retaining the updated
minimum volume per run or minimum mass per run requirements for fPM
compliance demonstration for coal-fired and integrated gasification
combined cycle (IGCC) EGUs (Question #5).
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\19\ For coal- and solid oil-fired EGUs, the 2024 Final Action
required a minimum catch for fPM of 6.0 milligrams (mg) or a minimum
sample volume of 4 dry standard cubic meters (dscm) per run.
Requirements for IGCCs included a minimum catch for fPM of 3 mg or a
minimum sample volume of 2 dscm. There were no changes to minimum
catch and same volume requirements for oil-fired EGUs.

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[[Page 25543]]

3. Hg Emission Standard for Lignite-Fired EGUs
In the 2012 MATS Final Rule, the EPA promulgated a beyond-the-floor
standard for Hg for the subcategory of existing coal-fired units
designed for ``low rank'' virgin coal (i.e., lignite) based on the use
of ACI for Hg control (77 FR 9304, February 16, 2012). The EPA
established a final Hg emission standard of 4.0 lb/TBtu for lignite-
fired utility boilers and 1.2 lb/TBtu for utility boilers firing all
other types of coal (including anthracitic coal, bituminous coal,
subbituminous coal, and coal refuse).
The 2024 Final Action lowered the Hg standard for lignite-fired
EGUs from 4.0 lb/TBtu to 1.2 lb/TBtu based on the EPA's determination
that commercially available control technologies and improved methods
of operation would allow lignite-fired EGUs to meet a more stringent
emission standard. The more stringent Hg emission standard brought the
requirement for lignite-fired EGUs in line with the emission limitation
requirements of EGUs firing all other types of coal. In the 2024 Final
Action, the EPA reviewed coal composition information and concluded
that the Hg content, the halogen content, and the alkalinity were
similar between various lignite and subbituminous coals. In 2021, EGUs
firing subbituminous coal emitted Hg at an average annual rate of 0.6
lb Hg/TBtu with measured values as low as 0.1 lb/TBtu, which
demonstrated that EGUs burning subbituminous coal have utilized control
options to meet the 1.2 lb/TBtu emission standard despite the
challenges presented by the low halogen content in the coal (which
results in production of difficult-to-control elemental Hg vapor in the
flue gas stream) (88 FR 24880). Cost-effectiveness estimates for a
model 800 MW lignite-fired EGU using a range of sorbent injection rates
to meet the revised Hg emission standard were lower or consistent with
cost-effectiveness values for Hg controls that the EPA has found to be
acceptable in previous rulemakings.
After reviewing the revised emission standard that was promulgated
in the 2024 Final Action, the EPA is proposing to repeal the revised Hg
emission limit for lignite-fired EGUs because the revised standard was
based on insufficient available data demonstrating that lignite units
can meet the lower limit over the range of boiler types and variable
compositions of fuels used at lignite-fired EGUs.\20\ While the EPA
found that all 22 lignite-fired EGUs at 12 facilities would need to
control their Hg emissions to 95 percent or less to meet an emission
standard of 1.2 lb/TBtu in the 2024 Final Action, the Agency did not
demonstrate that this high level of Hg removal is achievable for all
lignite-fired units while taking into account the wide-ranging and
highly variable Hg content of the various lignite fuels. In fact, Hg
emission rates reported in the 2024 Final Action from units at 11 of
the 12 lignite facilities were well above the final 1.2 lb/TBtu
emission standard (89 FR 38548). The EPA, instead, relied on the
emission reduction performance of only two units (at the Twin Oaks
facility in Texas) that have achieved the revised emission standard (89
FR 38539, May 7, 2024). Between August 1 and September 19, 2023, a
series of Hg emissions performance tests were conducted on Twin Oaks
units 1 and 2. The average Hg emissions rate for the 30-boiler
operating day performance tests was 1.1 lb/TBtu for unit 1 and 0.9 lb/
TBtu for unit 2 (89 FR 38540, May 7, 2024). Further, in performance
testing for the previous year (2022), the average Hg emissions rate for
the 30-boiler operating day performance test was 0.9 lb/TBtu for unit 1
and 0.6 lb/TBtu for unit 2. However, these tests were conducted over a
limited operating period and are not sufficient to establish that
meeting a 1.2 lb/TBtu standard continuously is possible for all
lignite-fired EGUs.
---------------------------------------------------------------------------

\20\ In May 2021, the EPA issued a CAA section 114 request to
lignite facilities for Hg emissions and related operational
information. The request designated specific time periods which were
not representative of emissions achievable on a 30-day rolling
basis.
---------------------------------------------------------------------------

Furthermore, the Twin Oaks facility, constructed in the early
1990s, is one of the newest lignite units and uses a circulating
fluidized bed (CFB) combustor, which affects its Hg emissions.
Conventional boilers use coal that is pulverized to a very fine
particle size to maximize combustion efficiency and to minimize
unburned carbon. In contrast, the design of CFB combustors permits the
burning of larger-sized coal particles. Fluidized bed units typically
operate at lower temperatures compared to conventional boilers and have
longer fuel residence times. As a result, CFB combustors typically have
higher levels of unburned carbon present in the fly ash. The unburned
carbon particles behave much like injected activated carbon sorbent
and, coupled with the lower operating temperature and longer residence
time, can promote more efficient Hg removal as compared to that
observed from units using non-CFB boilers using conventional pulverized
coal combustors.
Other lignite-fired EGUs that utilize a CFB combustor also had
generally lower Hg emission rates. For instance, the 2022 measured Hg
rates reported in the 2024 Final Rule for the Red Hills facility in
Mississippi, which also employs CFB combustors, was 1.7 lb/TBtu,
compared to a range of 2.5-3.0 lb/TBtu for other lignite-fired EGUs in
the southern U.S. (89 FR 38548). Additionally, the lowest 2022 Hg
emissions from lignite-fired facilities in North Dakota were found at
Spiritwood Station, which also utilizes a CFB combustor. In revising
the Hg emission standard for lignite-fired EGUs in the 2024 Final
Action, the EPA failed to evaluate the achievability of the revised Hg
emission standard by affected sources that are not using the better
performing CFB combustor technology.
In addition, the EPA assumed that the revised Hg standard of 1.2
lb/TBtu could be met by injecting better performing powdered sorbents
using existing sorbent injection systems without the need for equipment
modifications or additions. However, industry commenters noted that
existing equipment at lignite-fired power plants may not be able to
achieve the 1.2 lb/TBtu Hg limit and that demonstration testing would
be required to determine a sorbent dosage rate, guaranteed injection
rate, and the emissions rate that can be achieved when considering the
Hg content variability of the lignite. Commenters claimed that
modifications to Hg control systems may be required in order to meet
the 1.2 lb/TBtu emission limit. The EPA did not consider such cost in
the final analysis.
Lastly, the Agency did not sufficiently investigate the complex
composition of lignite coals, including the variability of the Hg
content in the inlet fuel source and the corresponding reductions
needed to comply with the 1.2 lb/TBtu Hg emission standard. In the 2023
Proposal, the EPA explained how the halogen content of coal influences
the oxidation state of Hg in the flue gas stream and thus the
partitioning of Hg into elemental Hg vapor, oxidized Hg vapor, or
particle-bound Hg, which impacts Hg control approaches (78 FR 24875).
Lignites and subbituminous coals have lower halogen content compared to
bituminous coals and the Hg in the flue gas from boilers firing those
fuels tends to stay in the elemental vapor state, which is more
challenging to control. The EPA noted that pre-halogenated (typically
brominated) sorbents have been effectively utilized to control Hg
emissions at power plants firing low-halogen content subbituminous
coals. However, the EPA also noted that lignite

[[Page 25544]]

coals tend to contain higher amounts of sulfur (more similar to some
bituminous coals), which, under certain circumstances, can result in
the production of sulfur trioxide (SO<INF>3</INF>) in the flue gas
stream. SO<INF>3</INF> is known to inhibit the effectiveness of some
sorbents that are used for Hg control. The EPA acknowledged the
challenges with higher sulfur content coals, but noted that bituminous
coal-fired power plants had found ways to overcome those challenges--
sometimes by utilizing newly developed ``sulfur-tolerant'' sorbents.
However, while the EPA acknowledged the respective challenges that the
halogen and sulfur content of coal can have on Hg control in the 2024
Final Action, the EPA failed to address the impact of lower halogen
content coupled with higher sulfur on Hg control for lignite-fired
power plants. Subbituminous coals tend to have low content of both
halogen and sulfur, while bituminous coals tend to contain higher
levels of both halogen and sulfur. In comparison, lignites tend to have
low halogen content (similar to subbituminous coals) and higher sulfur
content (similar to some bituminous coals). The EPA failed to consider
the impact of this combination.
In addition, stakeholders provided data challenging the assumed
inlet value of 25.0 lb/TBtu used in modeling in the 2024 Final Action.
For example, historical data indicate that lignite seams near the San
Miguel plant in Texas result in coal feeds that have an average Hg
inlet content of 34.0 lb/TBtu (Docket ID No. EPA-HQ-OAR-2018-0794-
5965). As a result, San Miguel would need to achieve an average control
rate of 96.3 percent to meet the new standard (Docket ID No. EPA-HQ-
OAR-2018-0794-5965). Additionally, monthly fluctuations in Hg content
could require even higher control levels at least half the time.
Ignoring monthly variability not only leads to an underestimation of
costs associated with Hg removal but also overlooks control device
modifications and enhancements required to achieve pollution control
levels exceeding 90 percent. For these reasons, the EPA is proposing to
repeal the Hg emission limit for lignite-fired EGUs that was
promulgated in the 2024 Final Action and revert to the Hg emission
limit--4.0 lb/TBtu--that was promulgated in the 2012 MATS Final Rule.
The EPA solicits comment on the proposed repeal of the more stringent
Hg standard for lignite-fired EGUs because of insufficient data
demonstrating the standard can be met by lignite-fired EGUs with a
range of boiler types and variable fuel composition (Question #6).
Additionally, the EPA solicits comment on if there are alternative
cost-effective and achievable Hg standards for lignite-fired EGUs that
are based on developments in practices, processes, and control
technologies that we should consider instead of repealing the 1.2 lb/
TBtu standard (Question #7).

B. Statutory Authority of CAA Section 112

Under CAA section 112(d)(6), the EPA is required ``to review, and
revise as necessary (taking into account developments in practices,
processes, and control technologies), emission standards promulgated
under this section no less often than every 8 years'' (emphasis added).
When deciding to revise standards pursuant to CAA section 112(d)(6),
the EPA can consider the costs of developments in practices, processes,
and control technologies. See Ass'n of Battery Recyclers, Inc. v. EPA,
716 F.3d 667, 673-74 (D.C. Cir. 2013); see also Nat'l Ass'n for Surface
Finishing v. EPA, 795 F.3d 1, 11 (D.C. Cir. 2015). Given the high costs
and potential technical feasibility concerns with implementing the
revised standards under the 2024 Final Action, the EPA is also
proposing, as an additional and complementary basis for this action, to
find that the 2024 changes were not ``necessary'' under CAA section
112(d)(6).
In addition, the EPA solicits comment on whether a technology
review conducted under CAA section 112(d)(6) should take into
consideration whether any meaningful risk reduction would be obtained
from further reducing HAP emissions under the technology review. As
stated in section II, the 2020 Residual Risk Review found the residual
risks due to emissions of air toxics to be acceptable from the Coal-
and Oil-Fired EGU source category and determined that the current
NESHAP (as promulgated in the 2012 MATS Final Rule) provided an ample
margin of safety to protect public health and prevent an adverse
environmental effect.\21\ The results of the chronic inhalation cancer
risk assessment based on actual emissions, as shown in table 1 of this
preamble, indicated that the estimated maximum individual lifetime
cancer risk (cancer MIR) was 9-in-1 million, with nickel emissions from
certain oil-fired EGUs as the major contributor to the risk.
Approximately 193,000 people were estimated to have cancer risks at or
above 1-in-1 million from HAP emitted from four facilities in this
source category--all of which resulted from oil-fired sources in Puerto
Rico. The highest estimated risk from any coal-fired EGU was 0.3-in-1
million. The results of the risk analysis thus indicated that both the
actual and allowable inhalation cancer risk to the individual most
exposed was well below 100-in-1 million, which is the EPA's presumptive
limit of acceptability. Therefore, the EPA solicits comment on whether,
when weighing the costs associated with developments under a CAA
section 112(d)(6) technology review, the Agency should also consider
whether there would be a meaningful risk reduction from lowering HAP
emissions based on potential revisions to the emission standards
resulting from those developments (Question #8).
---------------------------------------------------------------------------

\21\ In the 2023 Proposal, the EPA determined not to reopen the
2020 Residual Risk Review, and accordingly did not propose any
revisions to that review.
---------------------------------------------------------------------------

C. Reliance Interests in Reevaluating the 2024 Final Action

In proposing to repeal amendments to MATS introduced in the 2024
Final Action, the EPA is considering reliance interests of impacted
stakeholders. Dep't of Homeland Sec. v. Regents of the Univ. of Cal.,
591 U.S. 1, 30 (2020). Because the effective date of the revised
standards introduced in the 2024 Final Action is not until July 8,
2027, the EPA does not anticipate significant reliance interest in the
2024 revised standards. However, the EPA requests comments on the
reliance interests implicated by this proposed action (Question #9).

IV. Request for Comments

The EPA solicits comments on all aspects of this proposed action. A
summary of questions for which the EPA invites specific comment is
listed below. The EPA requests commenters number their responses with
the question number when responding to each question.
Question #1: Should the revision of the fPM standard for existing
coal-fired EGUs from 0.030 lb/MMBtu to 0.010 lb/MMBtu be repealed, as
proposed, because the cost effectiveness of the revised fPM standard is
inconsistent with the EPA's prior CAA section 112(d)(6) technology
review determinations for other source categories?
Question #2: Are there other cost-effective and achievable fPM
limits for existing coal-fired EGUs that are based on developments in
practices, processes, and control technologies that the EPA should
consider as an alternative to repealing the 0.010 lb/MMBtu standard?

[[Page 25545]]

Question #3: Should the quarterly stack testing and PM CPMS
compliance demonstration options for the fPM standard be reinstated, as
proposed, because other air pollution control indicators can adequately
inform operators of malfunctions and that the higher costs for PM CEMS
do not outweigh the advantages of more efficient pollutant abatement
and more transparency of EGU fPM emissions?
Question #4: Should the Low Emitting EGU (LEE) program for fPM and
non-Hg HAP metals be reinstated, as proposed?
Question #5: Should the EPA retain, as proposed, the updated
minimum volume per run or minimum mass per run requirements for fPM
compliance demonstration for coal-fired and IGCC EGUs?
Question #6: Should the revision of the Hg standard for lignite-
fired EGUs from 4.0 lb/TBtu to 1.2 lb/TBtu be repealed, as proposed,
because of insufficient data demonstrating the standard can be met by
lignite-fired EGUs with a range of boiler types and variable fuel
composition?
Question #7: Are there other achievable and cost-effective Hg
standards for lignite-fired EGUs that are based on developments in
practices, processes, and control technologies that the EPA should
consider as an alternative to repealing the 1.2 lb/TBtu standard?
Question #8: Should the Agency consider whether, when weighing the
costs associated with developments under a CAA section 112(d)(6)
technology review, there would be any meaningful risk reduction from
reductions in HAP emissions based on potential revisions to emission
standards resulting from those developments?
Question #9: Are there reliance interests implicated by the
proposed repeal of the 2024 revised standards that the EPA should
consider in this rulemaking?

V. Statutory and Executive Order Reviews

Additional information about these statutes and Executive orders
can be found at <a href="https://www.epa.gov/laws-regulations/laws-and-executive-orders">https://www.epa.gov/laws-regulations/laws-and-executive-orders</a>.

A. Executive Order 12866: Regulatory Planning and Review

This action is a significant action under E.O. 12866 Section
3(f)(1) that was submitted to the OMB for review. Any changes made in
response to OMB recommendations have been documented in the docket. The
EPA prepared an analysis of the potential costs and benefits associated
with this action. This analysis, Regulatory Impact Analysis for the
Repeal of Amendments to National Emission Standards for Hazardous Air
Pollutants: Coal- and Oil-Fired Electric Utility Steam Generating
Units, is available in the docket.
We present the estimated present values (PV) and equivalent
annualized values (EAV) of the estimated cost savings of repealing the
2024 Final Action in 2024 dollars over the 2028 to 2037 period,
discounted to 2025. In addition, the Agency presents the assessment for
specific snapshot years, consistent with historic practice. These
snapshot years are 2028, 2030, and 2035. The power industry's cost
savings are represented in this analysis as the change in electric
power generation costs due to the repeal of the 2024 Final Action
requirements. In simple terms, these cost savings are an estimate of
the decreased power industry expenditures resulting from the repeal of
the 2024 Final Action requirements.
Under this proposed action, the 2024 Final Action would no longer
reduce emissions of Hg and non-Hg HAP metals as projected in the 2024
MATS RTR RIA.\22\ The potential benefits from reductions of HAP were
not able to be monetized in the 2024 MATS RTR RIA, nor were potential
impacts from the 2024 Final Action requirement to use PM CEMS for
compliance demonstration. See section I.A for more details of the
proposed repeal of requirements.
---------------------------------------------------------------------------

\22\ ``Regulatory Impact Analysis for the Final National
Emission Standards for Hazardous Air Pollutants: Coal- and Oil-Fired
Electric Utility Steam Generating Units Review of the Residual Risk
and Technology Review'' (Ref. EPA-452/R-24-005). Docket ID No. EPA-
HQ-OAR-2018-0794-6966.
---------------------------------------------------------------------------

Table 2 presents the estimated cost savings of this proposed action
in 2024 dollars discounted to 2025. This table presents the PV and EAV
of these estimates discounted at 3 percent and 7 percent.

Table 2--Present Value and Equivalent Annualized Value of Compliance
Cost Savings Estimates of the Proposed Action From 2028-2037
[Millions of 2024$, discounted to 2025]
------------------------------------------------------------------------
3 Percent 7 Percent
discount discount
rate rate
------------------------------------------------------------------------
Present Value................................... 1,000 770
Equivalent Annualized Value..................... 120 110
------------------------------------------------------------------------

The full benefit-cost analysis, which is contained in the RIA for
this rulemaking, is consistent with Executive Order 12866 and is
available in the docket.

B. Executive Order 14192: Unleashing Prosperity Through Deregulation

This action is expected to be an Executive Order 14192 deregulatory
action. Details on the estimated cost savings of this proposed rule can
be found in the EPA's analysis of the potential costs and benefits
associated with this action.

C. Paperwork Reduction Act (PRA)

The information collection activities in this proposed rule have
been submitted for approval to the Office of Management and Budget
(OMB) under the PRA. The Information Collection Request (ICR) document
that the EPA prepared has been assigned EPA ICR number 2137.12. You can
find a copy of the ICR in the docket for this rule, and it is briefly
summarized here.
The information collection activities in this rule include
performance testing, continuous emission monitoring, notifications and
periodic reports, recording information, monitoring and the maintenance
of records. The information generated by these activities will be used
by the EPA to ensure that affected facilities comply with the emission
limits and other requirements. Records and reports are necessary to
enable delegated authorities to identify affected facilities that may
not be in compliance with the requirements. Based on reported
information, delegated authorities will decide which units and what
records or processes should be inspected. The recordkeeping
requirements require only the specific information needed to determine
compliance. These recordkeeping and reporting requirements are
specifically authorized by CAA section 114 (42 U.S.C. 7414). The
following burden and cost estimates represent the total burden and cost
for the information collection requirements of the NESHAP for Coal- and
Oil-Fired EGUs assuming the repeal of the amendments is finalized.
Respondents/affected entities: The respondents are owners or
operators of coal- and oil-fired EGUs. The NAICS codes for the coal-
and oil-fired EGU industry are 221112, 221122, and 921150.
Respondent's obligation to respond: Mandatory per 42 U.S.C. 7414 et
seq.
Estimated number of respondents: 192 per year.
Frequency of response: The frequency of responses varies depending
on the burden item. Responses include daily

[[Page 25546]]

calibrations, monthly recordkeeping activities, semiannual compliance
reports, and annual reports.
Total estimated burden: 181,000 hours (per year). Burden is defined
at 5 CFR 1320.3(b).
Total estimated cost: $73,800,000 (per year), includes $24,500,000
in annual labor costs and $49,400,000 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. The EPA will respond to any ICR-related
comments in the final rule. You may also send your ICR-related comments
to OMB's Office of Information and Regulatory Affairs using the
interface at <a href="http://www.reginfo.gov/public/do/PRAMain">www.reginfo.gov/public/do/PRAMain</a>. Find this information
collection by selecting ``Currently under Review--Open for Public
Comments'' or by using the search function. OMB must receive comments
no later than July 17, 2025.

D. Regulatory Flexibility Act (RFA)

The EPA certifies that this action will not have a significant
economic impact on a substantial number of small entities under the
RFA. In making this determination, the EPA concludes that the impact of
concern for this rule is any significant adverse economic impact on
small entities and that the agency is certifying that this rule will
not have a significant economic impact on a substantial number of small
entities because the rule relieves regulatory burden on the small
entities subject to the rule. This proposed action would lead to
reduction in EAV of costs over the 2028 to 2037 timeframe of about $120
and $110 million per year at discount rates of 3 percent and 7 percent,
respectively. Additionally, in the 2024 MATS RTR RIA, the EPA
identified 45 potentially affected EGUs owned by 24 small entities that
would together incur compliance costs of about $2.4 million (in 2024
dollars) in 2028, the year of compliance. Of these small entities, one
was projected to incur compliance cost reductions greater than 1
percent of baseline revenue, and two were projected to incur compliance
cost increases greater than 1 percent (relative to a baseline without
the requirements). The remaining 23 entities were not projected to
experience compliance cost changes of more than 1 percent. Under the
proposed repeal, these projected compliance cost changes for small
entities will be avoided. Consequently, the EPA expects that this
deregulatory action, if finalized as proposed, would relieve the
regulatory burden for facilities that, absent this proposed repeal,
would be affected by the provisions from the 2024 Final Action. As a
result, this action will not have a significant economic impact on a
substantial number of small entities under the RFA.

E. Unfunded Mandates Reform Act (UMRA)

This action does not contain an unfunded mandate of $100 million or
more (adjusted for inflation) as described in UMRA, 2 U.S.C. 1531-1538,
and does not significantly or uniquely affect small governments. The
costs involved in this action are estimated not to exceed $100 million
or more (adjusted for inflation) in any one year.

F. 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.

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

This action does not have tribal implications as specified in
Executive Order 13175. It will not have substantial direct effects on
tribal governments, on the relationship between the Federal Government
and Indian tribes, or on the distribution of power and responsibilities
between the Federal Government and Indian tribes, as specified in
Executive Order 13175. Thus, Executive Order 13175 does not apply to
the action.
Consistent with the EPA Policy on Consultation and Coordination
with Indian Tribes, the EPA will engage in consultation with tribal
officials during the development of this action.

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

Executive Order 13045 directs Federal agencies to include an
evaluation of the health and safety effects of the planned regulation
on children in Federal health and safety standards and explain why the
regulation is preferable to potentially effective and reasonably
feasible alternatives. This action is not subject to Executive Order
13045 because the EPA does not believe the environmental health risks
or safety risks addressed by this action present a disproportionate
risk to children. Emissions from this source category include HAP like
Hg and lead, which are known developmental toxicants. However, the 2020
residual risk assessment showed all modeled exposures to HAP from these
facilities to be below levels of public health concern (85 FR 31286).
Therefore, this action does not present or address disproportionate
risk to children.

I. 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. The 2024 MATS RTR RIA projected the
2024 Final Action would have minimal impacts on average retail
electricity prices across the contiguous U.S., coal-fired electricity
generation, natural gas-fired electricity generation, and utility power
sector delivered natural gas prices. This proposed action will prevent
any adverse energy impacts that might have occurred under the 2024
Final Action. Details of the projected energy effects are presented in
section 3 of the RIA, which is in the public docket.

J. National Technology Transfer and Advancement Act (NTTAA) and 1 CFR
Part 51

This rulemaking does not involve technical standards.

List of Subjects in 40 CFR Part 63

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

Lee Zeldin,
Administrator.
[FR Doc. 2025-10992 Filed 6-16-25; 8:45 am]
BILLING CODE 6560-50-P

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