
[Federal Register Volume 88, Number 221 (Friday, November 17, 2023)]
[Rules and Regulations]
[Pages 80480-80545]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-25269]



[[Page 80479]]

Vol. 88

Friday,

No. 221

November 17, 2023

Part IV





Environmental Protection Agency





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40 CFR Part 60





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Adoption and Submittal of State Plans for Designated Facilities: 
Implementing Regulations Under Clean Air Act Section 111(d); Final Rule

  Federal Register / Vol. 88 , No. 221 / Friday, November 17, 2023 / 
Rules and Regulations  

[[Page 80480]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2021-0527; FRL-8606-01-OAR]
RIN 2060-AV48


Adoption and Submittal of State Plans for Designated Facilities: 
Implementing Regulations Under Clean Air Act Section 111(d)

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is finalizing 
amendments to the regulations that govern the processes and timelines 
for state and Federal plans to implement emission guidelines under 
Clean Air Act (CAA) New Source Performance Standards for existing 
sources (the ``implementing regulations''). The amendments include 
revisions to the timing requirements for state and the EPA actions 
related to plans; the addition of mechanisms to improve flexibility and 
efficiency in plan processes; and new requirements for demonstration of 
timely meaningful engagement with pertinent stakeholders--including, 
but not limited to, industry, small businesses, and communities most 
affected by and vulnerable to the impacts of the plan. This action 
additionally provides a process for states' consideration of `remaining 
useful life and other factors' (RULOF) in applying a standard of 
performance; amends the definition of standard of performance in the 
implementing regulations; and clarifies compliance flexibilities that 
states may choose to incorporate into state plans, including trading or 
averaging. Finally, this action adds requirements for the electronic 
submission of state plans and provides several other clarifications and 
minor revisions to the implementing regulations.

DATES: This final rule is effective on December 18, 2023.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-HQ-OAR-2021-0527. All documents in the docket are 
listed on the https://www.regulations.gov/ website. Although listed, 
some information is not publicly available, e.g., Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the internet and will be publicly available only in hard 
copy form. Publicly available docket materials are available 
electronically through https://www.regulations.gov/.

FOR FURTHER INFORMATION CONTACT: For questions about this action 
contact Dr. Michelle Bergin, Sector Policies and Programs Division 
(Mail Code D205-01), Office of Air Quality Planning and Standards, U.S. 
Environmental Protection Agency, 109 T.W. Alexander Drive, P.O. Box 
12055, Research Triangle Park, North Carolina 27711; telephone number: 
(919) 541-2726; email address: [email protected].

SUPPLEMENTARY INFORMATION: 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:

ACE Affordable Clean Energy Rule
ALA American Lung Association
BSER Best System of Emission Reduction
CAA Clean Air Act
CBI confidential business information
CDX Central Data Exchange
CFR Code of Federal Regulations
EG Emission Guideline
EGU electric generating unit
EJ environmental justice
EPA Environmental Protection Agency
FIP Federal Implementation Plan
ICR Information Collection Request
IoP Increments of Progress
NAAQS National Ambient Air Quality Standards
OAQPS Office of Air Quality Planning and Standards
OMB Office of Management and Budget
PRA Paperwork Reduction Act
PM2.5 fine particulate matter (2.5 microns and less)
RTC Response to Comments document
RFA Regulatory Flexibility Act
RIN Regulatory Information Number
RULOF remaining useful life and other factors
SIP State Implementation Plan
SpeCS State Planning Electronic Collaboration System
TAR Tribal Authority Rule
TAS Treatment as a State
TIP Tribal Implementation Plan
UMRA Unfunded Mandates Reform Act
U.S.C. United States Code

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

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related 
information?
    C. Judicial Review and Administrative Review
II. Background
    A. What is the statutory authority for this action?
    B. What is the background for this action?
    C. What changes did we propose?
    D. What outreach and engagement did the EPA conduct?
III. What actions are we finalizing and what is our rationale for 
such decisions?
    A. Revised Implementing Timelines
    B. Federal Plan Authority and Timeline Upon Failure to Submit a 
Plan
    C. Outreach and Meaningful Engagement
    D. Regulatory Mechanisms for State Plan Implementation
    E. Remaining Useful Life and Other Factors (RULOF) Provisions
    F. Provision for Electronic Submission of State Plans
    G. Other Proposed Modifications and Clarifications
IV. Summary of Cost, Environmental, and Economic Impacts
V. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review; 
Executive Order 13563: Improving Regulation and Regulatory Review; 
and Executive Order 14094: Modernizing Regulatory Review
    B. Paperwork Reduction Act (PRA)
    C. Regulatory Flexibility Act (RFA)
    D. Unfunded Mandates Reform Act (UMRA)
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health Risks and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act (NTTAA)
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act (CRA)

I. General Information

A. Does this action apply to me?

    This action applies for the development and adoption of plans for 
implementation of CAA section 111(d) final emission guidelines (EGs) 
published in the Federal Register after July 8, 2019. In particular, 
this action applies to states in the development and submittal of state 
plans and to the EPA in processing state plan submissions and to the 
EPA in promulgating Federal plans. After the EPA promulgates a final 
EG, each state that has one or more designated facilities must develop, 
adopt, and submit to the EPA a state plan under CAA section 111(d). The 
term ``designated facility'' means ``any existing facility . . . which 
emits a designated pollutant and which would be subject to a standard 
of performance for that pollutant if the existing facility were an 
affected facility [i.e., a new source].'' See 40 CFR 60.21a(b). If a 
state fails to submit a plan or if the EPA determines that a state plan 
is not

[[Page 80481]]

satisfactory, the EPA has the authority to establish a Federal CAA 
section 111(d) plan for designated facilities located in the state.
    Under the Tribal Authority Rule (TAR), eligible tribes may seek 
approval to implement a plan under CAA section 111(d) in a manner 
similar to a state. See 40 CFR part 49, subpart A. Tribes may, but are 
not required to, seek approval for treatment in a manner similar to a 
state (treatment as a state; TAS) for purposes of developing a Tribal 
Implementation Plan (TIP) implementing an EG. If a tribe obtains 
approval and submits a TIP, the EPA will use similar timelines and 
criteria and will follow similar procedures as those for state plans. 
Tribes that choose to develop plans will have the same flexibilities 
available to states in this process. The TAR authorizes tribes to 
develop and implement one or more of its own air quality programs, or 
portions thereof, under the CAA; however, it does not require tribes to 
develop a CAA program. Tribes may implement programs that are most 
relevant to their air quality needs. A tribe with an approved TAS under 
TAR for CAA 111(d) is not required to resubmit TAS approval to 
implement an EG subject to subpart Ba.\1\ If a tribe does not seek and 
obtain the authority from the EPA to establish a TIP, the EPA has the 
authority to establish a Federal CAA section 111(d) plan for designated 
facilities that are located in areas of Indian country. A Federal plan 
would apply to all designated facilities located in the areas of Indian 
country covered by the Federal plan unless and until the EPA approves a 
TIP applicable to those facilities.
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    \1\ See the EPA website, https://www.epa.gov/tribal/tribes-approved-treatment-state-tas, for information on those tribes that 
have treatment as a state for specific environmental regulatory 
programs, administrative functions, and grant programs.
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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 final action at 
https://www.epa.gov/stationary-sources-air-pollution/adoption-and-submittal-state-plans-designated-facilities-40-cfr. Following 
publication in the Federal Register, the EPA will post the Federal 
Register version of the final rule, a memorandum showing the rule edits 
finalized in this action, and key supporting documents at this same 
website.

C. Judicial Review and Administrative Review

    Section 307(b)(1) of the CAA governs judicial review of final 
actions by the EPA. This section provides, in part, that petitions for 
review must be filed in the D.C. Circuit: (i) when the agency action 
consists of ``nationally applicable regulations promulgated, or final 
actions taken, by the Administrator,'' or (ii) when such action is 
locally or regionally applicable, but ``such action is based on a 
determination of nationwide scope or effect and if in taking such 
action the Administrator finds and publishes that such action is based 
on such a determination.'' For locally or regionally applicable final 
actions, the CAA reserves to the EPA complete discretion whether to 
invoke the exception in (ii) described in the preceding sentence.\2\
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    \2\ Sierra Club v. EPA, 47 F.4th 738, 745 (D.C. Cir. 2022) 
(``EPA's decision whether to make and publish a finding of 
nationwide scope or effect is committed to the agency's discretion 
and thus is unreviewable''); Texas v. EPA, 983 F.3d 826, 834-35 (5th 
Cir. 2020).
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    This action is ``nationally applicable'' within the meaning of CAA 
section 307(b)(1). The final rule governs the EPA's promulgation of 
emission guidelines under CAA section 111(d), which are nationally 
applicable regulations for which judicial review is available only in 
the U.S. Court of Appeals for the District of Columbia (D.C. Circuit) 
pursuant to CAA section 307(b)(1).\3\ Moreover, it revises the 
generally applicable, nationally consistent implementing regulations 
that govern the development and submission for all states of state 
plans and the EPA's development of Federal plans pursuant to EGs under 
CAA section 111(d), as well as the EPA's review of states' plans.
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    \3\ See, e.g., Nat'l Waste & Recyling Ass'n v. EPA, No. 16-1371 
(D.C. Cir. 2016) (consolidated challenges to the CAA section 111(d) 
emissions guidelines for municipal solid waste landfills in the D.C. 
Circuit); Am. Lung Ass'n v. EPA, 985 F.3d 914 (D.C. Cir. 2021) 
(consolidated challenges to, among other things, the CAA section 
111(d) emission guidelines for fossil fuel-fired electric generating 
units known as the Affordable Clean Energy Rule).
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    In the alternative, to the extent a court finds this final action 
to be locally or regionally applicable, the Administrator is exercising 
the complete discretion afforded to him under the CAA to make and 
publish a finding that this action is based on a determination of 
``nationwide scope or effect'' within the meaning of CAA section 
307(b)(1).\4\ As explained above, this final action is revising a 
single set of nationally consistent implementing regulations that apply 
to every state that must develop a state plan submission pursuant to 
CAA section 111(d) and an EPA-issued EG, as well as apply to the EPA 
when it reviews state plan submissions. The regulations also govern the 
EPA's development of EGs pursuant to CAA section 111(d), which apply to 
every state that contains designated facilities.
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    \4\ In deciding whether to invoke the exception by making and 
publishing a finding that an action is based on a determination of 
nationwide scope or effect, the Administrator takes into account a 
number of policy considerations, including his judgment balancing 
the benefit of obtaining the D.C. Circuit's authoritative 
centralized review versus allowing development of the issue in other 
contexts and the best use of agency resources.
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    The Administrator finds that this is a matter on which national 
uniformity in judicial resolution of any petitions for review is 
desirable, to take advantage of the D.C. Circuit's administrative law 
expertise, and to facilitate the orderly development of the law under 
the Act. The Administrator also finds that consolidated review of this 
action in the D.C. Circuit will avoid piecemeal litigation in the 
regional circuits, further judicial economy, and eliminate the risk of 
inconsistent results, and that a nationally consistent approach to 
implementation of EGs pursuant to CAA section 111(d) constitutes the 
best use of agency resources.
    For these reasons, this final action is nationally applicable or, 
alternatively, the Administrator is exercising the complete discretion 
afforded to him by the CAA and finds that this final action is based on 
a determination of nationwide scope or effect for purposes of CAA 
section 307(b)(1) and is publishing that finding in the Federal 
Register. Under section 307(b)(1) of the CAA, petitions for judicial 
review of this action must be filed in the United States Court of 
Appeals for the District of Columbia Circuit by January 16, 2024. Under 
CAA section 307(b)(2), the requirements established by this final rule 
may not be challenged separately in any civil or criminal proceedings 
brought by the EPA to enforce the requirements.
    Additionally, pursuant to CAA section 307(d)(1)(V), the 
Administrator determines that this action is subject to the provisions 
of CAA section 307(d). The EPA made this determination at proposal and 
has complied with the applicable procedural requirements in the course 
of this rulemaking. Section 307(d)(1)(V) of the CAA provides that the 
provisions of CAA section 307(d) apply to ``such other actions as the 
Administrator may determine.'' Section 307(d)(7)(B) of the CAA further 
provides that ``[o]nly an objection to a rule or procedure which was 
raised with reasonable specificity during the period

[[Page 80482]]

for public comment (including any public hearing) may be raised during 
judicial review.'' This section also provides a mechanism for the EPA 
to convene a proceeding for reconsideration, ``[i]f the person raising 
an objection can demonstrate to the Administrator that it was 
impracticable to raise such objection within [the period for public 
comment] or if the grounds for such objection arose after the period 
for public comment (but within the time specified for judicial review) 
and if such objection is of central relevance to the outcome of the 
rule.'' Any person seeking to make such a demonstration should submit a 
Petition for Reconsideration to the Office of the Administrator, U.S. 
Environmental Protection Agency, Room 3000, WJC South Building, 1200 
Pennsylvania Ave. NW, Washington, DC 20460, with a copy to both the 
person listed in the preceding FOR FURTHER INFORMATION CONTACT section, 
and the Associate General Counsel for the Air and Radiation Law Office, 
Office of General Counsel (Mail Code 2344A), U.S. Environmental 
Protection Agency, 1200 Pennsylvania Ave. NW, Washington, DC 20460.
    The EPA notes that the individual regulatory provisions it is 
revising or finalizing in this action are severable from one another 
because each is supported by an independent rationale. That is, the 
individual subsections within each of the sections of subpart Ba are 
generally justified independently and are therefore severable for 
purposes of judicial review.

II. Background

A. What is the statutory authority for this action?

    The statutory authority for this action is provided by CAA section 
111 (42 U.S.C. 7411). As described further in the next section, CAA 
section 111 requires the EPA to establish standards of performance for 
certain categories of stationary sources that, in the Administrator's 
judgment, ``cause[ ], or contribute[] significantly to, air pollution 
which may reasonably be anticipated to endanger public health or 
welfare.'' CAA section 111(b) provides the EPA's authority to regulate 
new and modified sources, while CAA section 111(d) directs the EPA to 
``prescribe regulations which shall establish a procedure'' for states 
to submit plans to the EPA that establish standards of performance for 
existing sources of certain air pollutants to which a standard would 
apply if such existing source were a new source. The EPA addresses its 
obligation under CAA section 111(d) to establish a procedure for states 
to submit plans both through its promulgation of general implementing 
regulations, including those addressed by this action, and through 
promulgation of EGs for specific source categories. Additional 
statutory authority for this action is provided by section 301 of the 
CAA (42 U.S.C. 7601), which contains general provisions for the 
administration of the CAA, including the authority for the 
Administrator to ``prescribe such regulations as are necessary to carry 
out [the] functions'' of the CAA under section 301(a)(1).

B. What is the background for this action?

    Clean Air Act section 111(d) governs the establishment of standards 
of performance for existing stationary sources. CAA section 111(d) 
directs the EPA to ``prescribe regulations which shall establish a 
procedure similar to that provided by [CAA section 110]'' for states to 
submit state plans that establish standards of performance for existing 
sources of certain air pollutants to which a standard of performance 
would apply if such an existing source were a new source under CAA 
section 111(b). Therefore, an existing source can only be regulated 
under CAA section 111(d) if it belongs to a source category that is 
regulated under CAA section 111(b). The EPA's implementing regulations 
use the term ``designated facility'' to identify those existing 
sources. See 40 CFR 60.21a(b).
    CAA section 111(b)(1)(A) requires that a source category be 
included on the list for regulation if, ``in [the EPA Administrator's] 
judgment it causes, or contributes significantly to, air pollution 
which may reasonably be anticipated to endanger public health or 
welfare.'' Once a source category is listed, CAA section 111(b)(1)(B) 
requires that the EPA propose and then promulgate ``standards of 
performance'' for new sources in such source category. CAA section 
111(a)(1) defines a ``standard of performance'' as ``a standard for 
emissions of air pollutants which reflects the degree of emission 
limitation achievable through the application of the best system of 
emission reduction which (taking into account the cost of achieving 
such reduction and any nonair quality health and environmental impact 
and energy requirements) the Administrator determines has been 
adequately demonstrated.'' This provision requires the EPA to determine 
both the best system of emission reduction (BSER) for the regulated 
source category and the degree of emission limitation achievable 
through application of the BSER. The EPA must then, under CAA section 
111(b)(1)(B), promulgate standards of performance for new sources that 
reflect that level of stringency.
    Once the EPA promulgates standards of performance for new sources 
within a particular source category, the EPA is required, in certain 
circumstances, to regulate emissions from existing sources in that same 
source category.\5\ Under CAA section 111(d), the Agency has, to date, 
issued EGs regulating five pollutants from six source categories that 
are currently in effect (i.e., sulfuric acid plants (acid mist), 
phosphate fertilizer plants (fluorides), primary aluminum plants 
(fluorides), kraft pulp plants (total reduced sulfur), municipal solid 
waste landfills (landfill gases)), and fossil fuel-fired electric 
generating units (greenhouse gases [GHGs]). See ``Phosphate Fertilizer 
Plants; Final Guideline Document Availability,'' 42 FR 12022 (March 1, 
1977); ``Standards of Performance for New Stationary Sources; Emission 
Guideline for Sulfuric Acid Mist,'' 42 FR 55796 (October 18, 1977); 
``Kraft Pulp Mills, Notice of Availability of Final Guideline 
Document,'' 44 FR 29828 (May 22, 1979); ``Primary Aluminum Plants; 
Availability of Final Guideline Document,'' 45 FR 26294 (April 17, 
1980); ``Emission Guidelines and Compliance Times for Municipal Solid 
Waste Landfills,'' 81 FR 59276 (August 29, 2016); ``Repeal of the Clean 
Power Plan; Emission Guidelines for Greenhouse Gas Emissions From 
Existing Electric Utility Generating Units; Revisions to Emission 
Guidelines Implementing Regulations,'' 84 FR 32520 (July 8, 2019) 
(Affordable Clean Energy (ACE) Rule).6 7 Additionally, the

[[Page 80483]]

EPA recently proposed EGs addressing GHG emissions from two different 
source categories. On November 15, 2021, the EPA proposed EGs to 
regulate GHG emissions (in the form of methane limitations) from 
sources in the oil and natural gas source category (86 FR 63110) and 
provided a supplemental proposal for that sector on December 6, 2022 
(87 FR 74702). On May 23, 2023, the EPA proposed to repeal the existing 
EG for GHG emissions from certain fossil fuel-fired electric generating 
units (the ACE Rule) and to promulgate a new EG in order to regulate 
GHG emissions (in the form of carbon dioxide limitations) from existing 
fossil fuel-fired electric generating units. 88 FR 33240. Finally, the 
Agency has regulated additional pollutants from solid waste 
incineration units under CAA section 129 and in accordance with CAA 
section 111(d).\8\
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    \5\ In accordance with CAA section 111(d), states are required 
to submit plans to establish standards of performance for existing 
sources for any air pollutant: (1) the emission of which is subject 
to a Federal New Source Performance Standard; and (2) which is 
neither a pollutant regulated under CAA section 108(a) (i.e., 
criteria air pollutants such as ground-level ozone and particulate 
matter, and their precursors, like volatile organic compound) or a 
hazardous air pollutant regulated from the same source category 
under CAA section 112. See also definition of ``designated 
pollutant'' in 40 CFR 60.21a(a).
    \6\ The EPA has also issued several EGs that have subsequently 
been repealed or vacated by the courts. The EPA regulated mercury 
from coal-fired electric power plants in a 2005 rule that was 
vacated by the D.C. Circuit, ``Standards of Performance for New and 
Existing Stationary Sources: Electric Utility Steam Generating 
Units; Final Rule,'' 70 FR 28606 (May 18, 2005) (Clean Air Mercury 
Rule), vacated by New Jersey v. EPA, 517 F.3d 574 (D.C. Cir. 2008). 
The EPA also issued CAA section 111(d) EGs regulating GHG emissions 
from fossil fuel-fired electric power plants in a 2015 rule, 
``Carbon Pollution Emission Guidelines for Existing Stationary 
Sources: Electric Utility Generating Units; Final Rule,'' 80 FR 
64662 (October 23, 2015) (Clean Power Plan). The EPA subsequently 
repealed and replaced the 2015 rule with the ACE Rule.
    \7\ The ACE Rule was initially vacated by Am. Lung Ass'n v. EPA, 
985 F.3d 914 (D.C. Cir. 2021). The Supreme Court subsequently 
reversed and remanded the D.C. Circuit's opinion, West Virginia v. 
EPA, 142 S. Ct. 2587 (June 30, 2022). On October 27, 2022, the D.C. 
Circuit amended its judgement and recalled the partial mandate 
vacating the ACE Rule, effectively reinstating ACE. Order, ALA v. 
EPA, No. 19-1140, ECF No. 1970895.
    \8\ CAA section 129 directs the EPA Administrator to develop 
regulations under CAA section 111 limiting emissions of nine air 
pollutants from four categories of solid waste incineration units.
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    The mechanism for regulating designated facilities \9\ under CAA 
section 111(d) differs from the mechanism for regulating new facilities 
under CAA section 111(b). Pursuant to CAA section 111(b), the EPA 
promulgates standards of performance that are directly applicable to 
new, modified, and reconstructed facilities in a specified source 
category. In contrast, CAA section 111(d) operates together with CAA 
section 111(a)(1) to collectively establish and define roles and 
responsibilities for both the EPA and the states in the regulation of 
designated facilities. Under the statutory framework, the EPA has the 
responsibility to determine the BSER for designated facilities, as well 
as the degree of emission limitation achievable through application of 
that BSER. The EPA identifies both the BSER and the degree of emission 
limitation as part of an EG, which it may typically reflect as a 
presumptive standard of performance or methodology for calculating a 
presumptive standard of performance for designated facilities. States 
use the EPA's presumptive standards of performance as the basis for 
establishing requirements for designated facilities in their state 
plans. In addition to standards of performance, CAA section 111(d)(1) 
requires state plans to include provisions for the implementation and 
enforcement of such standards. CAA section 111(d)(1) also requires the 
EPA's regulations to permit states, in applying a standard of 
performance to particular sources, to take into account the source's 
remaining useful life and other factors, a process addressed in more 
detail in section III.E of this preamble.
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    \9\ A ``designated facility'' is any existing facility which 
emits an air pollutant, the emissions of which are subject to a 
standard of performance for new stationary sources but for which air 
quality criteria have not been issues and that is not included on a 
list published under CAA section 108(a) or 112, and which would be 
subject to a standard of performance for that pollutant if the 
existing facility were a new facility. See 40 CFR 60.21a.
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    CAA section 111(d) directs the EPA to establish a procedure for the 
submission of state plans, which the EPA addresses both through its 
promulgation of general implementing regulations for section 111(d) and 
through promulgation of EGs for specific source categories. While CAA 
section 111(d)(1) authorizes states to develop state plans that 
establish standards of performance and provides states with certain 
discretion in determining the appropriate standards, CAA section 
111(d)(2) provides the EPA a specific oversight role with respect to 
such state plans. The states must submit their plans to the EPA, and 
the EPA must evaluate each state plan to determine whether each plan is 
``satisfactory.'' If a state fails to submit a plan or the EPA 
determines that a state plan is not satisfactory, the EPA has the 
``same authority'' to prescribe a Federal plan as it has to promulgate 
a Federal Implementation Plan (FIP) under CAA section 110(c).
    In 1975, the EPA issued the first general implementing regulations 
to prescribe the process for the adoption and submittal of state plans 
for designated facilities under CAA section 111(d) (codified at 40 CFR 
part 60, subpart B (subpart B)). 40 FR 53340 (November 17, 1975). 
Responding to the direction to ``establish a procedure similar to that 
provided by'' CAA section 110, in promulgating subpart B, the EPA 
aligned the timing requirements for state and Federal plans under CAA 
section 111(d) with the then-applicable timeframes for State 
Implementation Plans (SIPs) and FIPs prescribed in CAA section 110, as 
established by the 1970 CAA Amendments. The implementing regulations 
were not significantly revised after their original promulgation in 
1975 \10\ until 2019, when the EPA promulgated a new set of 
implementing regulations codified at 40 CFR part 60, subpart Ba 
(subpart Ba). 84 FR 32520 (July 8, 2019).
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    \10\ In 2012, the EPA revised several provisions of subpart B, 
mainly to include allowance systems as a form of standard of 
performance. 77 FR 9303 (February 16, 2012).
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    In promulgating subpart Ba in 2019, the EPA intended to update and 
modernize the implementing regulations to align the procedures for CAA 
section 111(d) state and Federal plans with CAA amendments made after 
subpart B was first promulgated in 1975. Notably, subpart B did not 
align either with CAA section 111(d) as amended by Congress in 1977 or 
with the timelines in CAA section 110 as amended by Congress in 1990. 
The EPA therefore considered it appropriate to update the implementing 
regulations for CAA section 111(d) to make changes similar to CAA 
section 110, given that section 111(d)(1) of the CAA directs the EPA to 
``prescribe regulations which shall establish a procedure similar to 
that provided by section 110'' of the CAA for states to submit plans to 
the EPA. In promulgating subpart Ba, the EPA directly aligned the 
timing requirements for CAA section 111(d) state and Federal plans (40 
CFR 60.23a(a)(1) and 60.27a(c), respectively) with the timing 
requirements for SIPs and FIPs under CAA section 110 (see CAA section 
110(a)(1) and 110(c)(1), respectively).
    In promulgating subpart Ba, the EPA also added the definition of 
``standard of performance'' (40 CFR 60.21a(f)) (defined under subpart B 
as ``emission standard'' (40 CFR 60.21(f))) and the ``remaining useful 
life'' provision (40 CFR 60.24a(e)) (referred under subpart B as the 
``variance'' provision (40 CFR 60.24(f))). The EPA further added 
required minimum administrative and technical criteria for inclusion in 
state plans (40 CFR 60.27a(g)). Applying these criteria, the EPA 
determines whether a state plan or portion of a plan submitted is 
complete (referred to as a completeness review). Once a state plan or 
portion of a plan is determined to be complete, the EPA must approve or 
disapprove the plan or portions of the plan. For details on the EPA's 
rationale for the promulgation of these provisions, see 84 FR 32520 
(July 8, 2019).
    The EPA proposed minor revisions to the subpart Ba applicability 
provision and is finalizing those revisions largely as proposed (see 
section III.G.2.a. of this preamble). As finalized in 2019, subpart Ba 
was applicable to any final 111(d) EG published, or the implementation 
of which was ongoing, after July 8, 2019. The EPA proposed revisions to 
this provision for clarity, including to

[[Page 80484]]

remove the phrase ``if implementation of such final guideline is 
ongoing.'' \11\ It did not propose to change the already-established 
applicability date. At the time of promulgation of this rule, there are 
no final EGs that have been published after July 8, 2019, so subpart Ba 
will not retroactively apply to the implementation of any EG. 
Specifically, the final EG for greenhouse gas emissions from existing 
electric utility generating units that was included in the ACE Rule was 
published on July 8, 2019; \12\ thus, subpart Ba as revised will not 
apply to that EG. Regardless, the EPA proposed to repeal the ACE Rule 
on May 23, 2023,\13\ and intends to finalize its repeal, at which point 
neither states nor the EPA will have any obligations under the ACE Rule 
and the potential applicability of subpart Ba to this EG will be moot. 
In contrast, the EPA has recently proposed two EGs that would regulate 
GHG emissions from designated facilities in the oil and natural gas 
industry (86 FR 63110, November 15, 2021; 87 FR 74702, December 6, 
2022) and in the power sector (88 FR 33240, May 23, 2023). If those EGs 
are finalized and to the extent that the final EGs do not contain EG-
specific requirements superseding subpart Ba provisions, subpart Ba as 
revised in this action will apply. Subpart B continues to apply to CAA 
section 111 EGs promulgated on or prior to July 8, 2019, and to EGs 
issued pursuant to CAA section 129.
---------------------------------------------------------------------------

    \11\ 87 FR 79176, 79208-09 (Dec. 23, 2022). As explained in 
section III.G.2.a. of this preamble, the EPA is finalizing the 
removal of this phrase from 40 CFR 60.20a(a).
    \12\ 84 FR 32520 (July 8, 2019).
    \13\ ``New source Performance Standards for Greenhouse Gas 
Emissions From New, Modified, and Reconstructed Fossil Fuel-Fired 
Electric Generating Units; Emission Guidelines for Greenhouse Gas 
Emissions From Existing Fossil Fuel-Fired Electric Generating Units; 
and Repeal of the Affordable Clean Energy Rule,'' 88 FR 33240 (May 
23, 2023).
---------------------------------------------------------------------------

    In January 2021, the D.C. Circuit vacated several provisions of 
subpart Ba related to timelines for state plans and Federal plans. Am. 
Lung Ass'n v. EPA, 985 F.3d 914, 991. (D.C. Cir. 2021) (ALA).\14\ In 
this vacatur, the court identified several flaws in the EPA's rationale 
for extending CAA section 111(d) state and Federal plan timelines. 
First, the court found that the EPA erred in adopting the timelines for 
SIPs and FIPs in CAA section 110 without meaningfully addressing the 
differences in the scale of effort required for development and 
evaluation of CAA section 110 SIPs, as compared with the scale of 
effort needed for CAA section 111(d) state plans. Id. at 992-93. The 
court also concluded that in promulgating the timelines in subpart Ba, 
the EPA failed to justify why the shorter deadlines under subpart B 
were unworkable. Id. at 993. Further, the court held that the EPA was 
required to consider the effect of its subpart Ba timelines on public 
health and welfare, consistent with the statutory purpose of CAA 
section 111(d). In the court's view, the EPA's ``complete failure to 
say anything at all about the public health and welfare implications of 
the extended timeframes'' meant that the EPA failed to consider an 
important aspect of the problem. Id. at 992 (citing Motor Vehicle Mfrs. 
Ass'n of U.S., Inc. v. State Farm Mut. Auto. Ins. Co. 463 U.S. 29, 43 
(1983)).
---------------------------------------------------------------------------

    \14\ The Supreme Court subsequently reversed and remanded the 
D.C. Circuit's opinion. West Virginia v. EPA, 142 S.Ct. 2587 (June 
30, 2022). However, no Petitioner sought certiorari on, and the 
Supreme Court's West Virginia decision did not implicate, the D.C. 
Circuit's vacatur of portions of subpart Ba. See Amended Judgment, 
ALA v. EPA, No. 19-1140 (D.C. Cir. October 27, 2022), ECF No. 
1970898 (ordering that petitions for review challenging the timing 
portion of implementing regulations be granted).
---------------------------------------------------------------------------

    Based on these reasons, the court vacated the timeline for state 
plan submissions after publication of a final EG (40 CFR 60.23a(a)(1)), 
the EPA's deadline for taking action on state plan submissions (40 CFR 
60.27a(b)), the EPA's deadline for promulgating a Federal plan (40 CFR 
60.27a(c)), and the timeline associated with requirements for 
increments of progress (IoPs; 40 CFR 60.24 (a(d)). Because of the 
vacatur, subpart Ba currently does not provide generally applicable 
timelines for state plan submissions, a deadline for the EPA's action 
on state plan submissions, a deadline for the EPA's promulgation of a 
Federal plan, or a timeline associated with requirements for IoPs. The 
EPA notes that while it is finalizing generally applicable timelines 
for the implementing regulations, a particular EG may supersede those 
generally applicable timelines with its own specific timelines. 40 CFR 
60.20a(a)(1). This may be appropriate, for example, based on the 
complexity of regulating a particular source category, such as a 
category with a large number of disparate facilities to be regulated.

C. What changes did we propose?

    On December 23, 2022, the EPA proposed several revisions to subpart 
Ba both to address the vacatur of the timing provisions by the D.C. 
Circuit in ALA and to further improve the state and Federal plan 
development and implementation process. See 87 FR 79176 (December 23, 
2022). In response to the ALA decision, the EPA proposed timeframes for 
(1) state plan submittal, (2) the timeline for the EPA to determine 
completeness of state plans, (3) the EPA's action on state plan 
submissions, (4) the EPA's promulgation of a Federal plan, and (5) 
requirements to establish IoPs. Additionally, the EPA proposed to 
remove the publication in the Federal Register of a ``finding of 
failure to submit'' as the starting point for the clock to promulgate a 
Federal plan.
    In addition, the EPA proposed revisions to subpart Ba that would 
enhance the provision of reasonable notice and opportunity for public 
participation by requiring that states, as part of the state plan 
development or revision process, undertake outreach and meaningful 
engagement with a broad range of pertinent stakeholders. The EPA 
proposed to define pertinent stakeholders as including communities most 
affected by and vulnerable to the impacts of the plan or plan revision. 
Increased vulnerability, as described in the proposal, may be 
attributable, among other reasons, to both an accumulation of negative 
and lack of positive environmental, health, economic, or social 
conditions within these populations or communities.
    To improve flexibility and efficiency in the submission, review, 
approval, and implementation of state plans, the EPA proposed to 
include the following mechanisms in subpart Ba, all of which currently 
exist under CAA section 110: (1) partial approval/disapproval, (2) 
conditional approval, (3) allowance for parallel processing, (4) a 
mechanism for the EPA to call for plan revisions, and (5) an error 
correction mechanism.
    The EPA also proposed revisions to the existing regulations 
governing the ``remaining useful life and other factors'' (RULOF) 
provision of the statute. These proposed revisions were intended to 
promote clarity and increase consistency in situations where states or 
the EPA consider RULOF when applying standards of performance to 
individual sources and to ensure that such standards fulfill the 
statutory requirements of CAA section 111(d).
    Finally, the EPA proposed to require electronic submissions of 
state plans, as well as additional modifications and clarifications to 
subpart Ba. In particular, the EPA proposed clarifying amendments to 
the subpart Ba definition of standard of performance, along with a 
revised interpretation of CAA section 111(d) with respect to 
permissible compliance flexibilities. The EPA proposed to determine 
that, under appropriate circumstances, the Agency may approve state 
plans that authorize sources to meet their emission limits in the 
aggregate, such as through standards that permit compliance via

[[Page 80485]]

trading or averaging. In doing so, the EPA also proposed to conclude 
that CAA section 111 does not limit the BSER to controls that can be 
applied at and to the source.
    The EPA did not reopen any subpart Ba requirements other than the 
specific provisions that the EPA explicitly proposed to revise in the 
December 2022 notice of proposed rulemaking. Any comments received on 
the proposal that did not relate to the proposed revisions or additions 
are considered out of the scope of this action.

D. What outreach and engagement did the EPA conduct?

    The EPA conducted both pre- and post-proposal outreach and 
meaningful engagement events with environmental justice (EJ) 
communities, small businesses, states, and Tribes. On July 7 and July 
11, 2022, the EPA conducted two pre-proposal webinars for states 
addressing meaningful engagement for pertinent stakeholders, and on 
July 26, 2022, the Agency conducted a pre-proposal webinar for EJ 
communities and other key stakeholders about potential requirements for 
states to conduct meaningful engagement in developing their state 
plans. The EPA emailed an announcement of the subpart Ba proposal to 
Tribal nations and environmental justice communities via existing 
listservs on December 15, 2022. Post-proposal outreach during the 
public comment period with environmental justice communities included 
participation on the January 24, 2023 Environmental Justice National 
call and the January 26, 2023 National Tribal Air Association call. The 
EPA also conducted a public training webinar on January 31, 2023, for 
environmental justice community members and their representatives. 
Additionally, the EPA conducted post-proposal outreach with small 
businesses through the Small Business Environmental Assistance Program 
call on February 21, 2023, and with state environmental protection 
associations including the Association of Air Pollution Control 
Agencies on January 10, 2023, and the National Association of Clean Air 
Agencies on February 8, 2023.

III. What actions are we finalizing and what is our rationale for such 
decisions?

    This action finalizes amendments to subpart Ba, including the 
timing requirements for state plan submittal, the EPA's action on state 
plan submissions, the EPA's promulgation of a Federal plan, and the 
establishment of IoPs; the addition of five regulatory mechanisms to 
improve state plan processing: (1) partial approval/disapproval, (2) 
conditional approval, (3) allowance for parallel processing, (4) a 
mechanism for the EPA to call for plan revisions, and (5) an error 
correction mechanism; new requirements for meaningful engagement with 
pertinent stakeholders; and amended requirements for states' and the 
EPA's consideration of RULOF in applying a standard of performance in 
certain circumstances. This action also finalizes amendments to the 
subpart Ba definition of ``standard of performance'' and finalizes 
clarifications associated with CAA section 111(d) compliance 
flexibilities. Finally, this action finalizes requirements for the 
electronic submission of state plans and several other clarifications 
and minor revisions to the implementing regulations. While the EPA is 
finalizing most amendments as proposed, in response to comments 
submitted on the proposal, the EPA is extending the state plan 
submittal timeline and the timeline for requirement of IoPs; providing 
for additional flexibility and guidance for meaningful engagement; as 
well as revising and streamlining the requirements for accounting for 
RULOF in applying a less-stringent standard. There are also other 
provisions that we are finalizing with slight revisions relative to 
proposal. Further detail is provided in the following sections of this 
preamble and additional detailed responses to comments are located in 
the response to comment document (RTC).
    While this action amends the generally applicable requirements of 
subpart Ba, the EPA has recognized that, under certain circumstances, 
some provisions of the implementing regulations may not fit the needs 
of a specific EG. Therefore, the existing implementing regulations 
provide that each EG may include specific implementing provisions in 
addition to or that supersede the requirements of subpart Ba. 40 CFR 
60.20a(a)(1). The EPA will address source category-specific 
circumstances or facts that are not accommodated by the general 
provisions of subpart Ba through a specific EG, as the time and 
processes needed for development and adoption of state plans to 
implement the EG may be affected by unique characteristics of a source 
category. For example, if a proposed EG addresses a particularly large 
and complex source category that necessitates a relatively long 
timeframe for state planning, the EPA may provide a state plan 
submission deadline that is longer than the 18 months being finalized 
for subpart Ba.\15\
---------------------------------------------------------------------------

    \15\ See, e.g., 88 FR 33240, 33402-03 (May 23, 2023) (proposing 
a 24-month state plan submission deadline for the EG for GHG 
emissions from fossil fuel-fired electric generating units).
---------------------------------------------------------------------------

A. Revised Implementing Timelines

    As described in section II.A. of this preamble, the subpart Ba 
timing requirements were vacated by the D.C. Circuit in the ALA 
decision. These vacated timing requirements include: the timeline for 
state plan submissions, the timeline for the EPA to act on a state 
plan, the timeline for the EPA to promulgate a Federal plan, and the 
timeline that dictates when state plans must include IoPs. These 
timelines are all critical to ensuring that the emission reductions 
anticipated by the EPA when promulgating an EG become federally 
enforceable measures that are timely implemented by the designated 
facilities.
    The EPA proposed the following timelines to replace those vacated 
in ALA (87 FR 79176, Dec. 23, 2022): 15 months for state plan 
submissions after publication of a final EG; 60 days after submission 
for the EPA to determine if a plan is complete; 12 months for the EPA 
to take final action on a complete state plan (i.e., approve, 
disapprove); 12 months for the EPA to promulgate a Federal plan either 
after the state plan submission deadline if a state has failed to 
submit a complete plan, or after the EPA's disapproval of a state plan 
submission; and requiring state plans to include IoPs if the plan 
requires final compliance with standards of performance later than 16 
months after the plan submission deadline.\16\
---------------------------------------------------------------------------

    \16\ See 87 FR 79176, 79181-90 (Dec. 23, 2022).
---------------------------------------------------------------------------

    The EPA received numerous comments on these proposed timelines, 
most of which expressed support for timelines longer than those 
proposed. Some commenters asserted that the ALA decision does not 
direct the EPA to necessarily reduce timelines from those vacated, only 
to justify the timelines more fully. In particular, most commenters 
expressed the need for a longer state plan submittal timeline in order 
to accommodate state regulatory processes associated with plan 
submittals (i.e., legislative and/or administrative state processes), 
as well as to accommodate technical development of the plans and to 
implement the proposed meaningful engagement requirements. However, a 
few commenters noted that the EPA should not accommodate all lengthy 
state administrative processes that would unnecessarily postpone 
emission-reduction obligations. Some

[[Page 80486]]

commenters asserted that if the EPA were to finalize the state plan 
submittal timeline as proposed, the EPA should include a mechanism in 
the rule for states to request for extensions for state plan 
submittals.
    While some commenters also asserted the need for longer timelines 
associated with the EPA's obligations to take action on a state plan 
submittal and to promulgate a Federal plan when required, as well as 
allowing a longer timeline before IoPs are required in the state plans, 
other commenters supported the proposed timelines for these milestones 
based, among other concerns, on the need for timely protection of 
health and welfare and in consideration of the EPA's ability to extend 
timelines if warranted in a particular EG.
    In consideration of these comments and for the reasons described in 
detail in the sections that follow, the EPA is finalizing extended 
timelines from those proposed for submission of state plans, for 
significant state plan revisions, and for when IoPs must be considered 
for inclusion in state plans. The EPA is finalizing the remaining 
timelines as proposed. The EPA determined that these timelines will 
appropriately balance the need to reasonably accommodate the processes 
generally required by states and the EPA to develop, evaluate, and 
adopt plans to effectuate the EG with the need to ensure that 
designated facilities control emissions of dangerous pollutants as 
expeditiously as reasonably possible, consistent with the health and 
welfare-based objectives of CAA section 111(d). A summary of the 
timelines finalized in this action is shown in Table 1.
    The final subpart Ba timelines are applicable to any final EG 
published pursuant to CAA section 111(d) after July 8, 2019, including, 
if finalized, those recently proposed to regulate GHG emissions from 
sources in the oil and natural gas industry (86 FR 63110, November 15, 
202187 and FR 74702, December 6, 2022) and those proposed to regulate 
GHG emissions from fossil fuel-fired electric generating units (88 FR 
33240, May 23, 2023), to the extent that the final EGs do not contain 
provisions superseding any of these timelines in subpart Ba.\17\
---------------------------------------------------------------------------

    \17\ Under each of these EGs the EPA proposed to supersede the 
15-month state plan submittal timeline in proposed subpart Ba based 
on the size and complexity of the source sectors at issue.

Table 1--Final 40 CFR Part 60, Subpart Ba, Timeline Compared With Those Initially Proposed, Vacated From Subpart
                                             Ba, and From Subpart B
----------------------------------------------------------------------------------------------------------------
                                    2023 Subpart Ba     2022 Subpart Ba    Subpart Ba (2019)
          Process step                   final             proposal        vacated timelines   Subpart B (1975)
----------------------------------------------------------------------------------------------------------------
State Plan submittal after        18 months.........  15 months.........  36 months.........  9 months.
 publication of EG in the
 Federal Register.
State Plan completeness           60 days after       60 days after       *6 months after     N/A.
 determination.                    State Plan          State Plan          State Plan
                                   submission.         submission.         submission.
State Plan evaluation...........  12 months after     12 months after     12 months after     4 months after
                                   completeness.       completeness.       completeness.       State Plan
                                                                                               submittal
                                                                                               deadline.
EPA Federal Plan promulgation...  12 months after     12 months after     24 months after     6 months after
                                   failure to submit   failure to submit   finding of          State Plan
                                   or disapproval.     or disapproval.     failure to submit   submittal
                                                                           or disapproval.     deadline.
Requirements for Increments of    If compliance is    If compliance is    If compliance is    If compliance is
 Progress after submittal          >20 months.         >16 months.         >24 months.         >12 months.
 deadline.
----------------------------------------------------------------------------------------------------------------
* Although the timeline for the state plan completeness determinations was not vacated, the EPA has evaluated
  this timeline light of the court vacatur of the related timelines.

    As described in greater detail in section II. of this preamble, the 
D.C. Circuit's vacatur of the extended timelines in subpart Ba was 
based both on the EPA's failure to substantiate the necessity for the 
additional time at each step of the administrative process, and the 
EPA's failure to address how those extended implementation timelines 
would impact public health and welfare. Accordingly, the EPA has 
evaluated these factors and is finalizing timelines, as described in 
the following sections, based on the minimum administrative time 
reasonably necessary for each step in the implementation process, thus 
minimizing impacts on public health and welfare by proceeding as 
expeditiously as reasonably possible while accommodating the time 
needed for states or the EPA to develop an effective plan. This 
approach addresses both aspects of the ALA decision because the EPA and 
states will take no longer than necessary to develop and adopt plans 
that impose requirements consistent with the overall objectives of CAA 
section 111(d).
    The EPA acknowledges these timelines are not identical to those for 
SIPs under CAA section 110. This is consistent with the requirement of 
CAA section 111(d) that the EPA promulgate a procedure ``similar'' to 
that of CAA section 110, rather than an identical procedure. This is 
also consistent with the ALA decision, which requires the EPA to 
``engage meaningfully with the different scale'' of CAA section 111(d) 
and 110 plans. 985 F.3d at 993. In proposing the revised timelines, the 
EPA evaluated each step of the state plan implementation process to 
independently determine the appropriate duration needed to accomplish a 
given step as part of the overall process. After receiving comments on 
the proposed timelines, the EPA again evaluated each step in light of 
the new information; the timelines being finalized in this action 
represent the Agency's revised assessment of the most reasonably 
expeditious timelines that are appropriate to provide as a default for 
EGs under these generally applicable implementing regulations.
    The EPA recognizes that, under certain circumstances, the timelines 
being finalized in this action may not fit the needs of a specific EG 
because of the specific characteristics of an EG. The EPA will address 
source category-specific circumstances or facts that are not 
accommodated by the timelines of subpart Ba through a specific EG. 
Examples of circumstances that may require consideration for different

[[Page 80487]]

timelines could include EGs that require states to perform extensive 
engineering and/or economic analyses before submitting their plans; EGs 
with an exceptional need to expedite implementation (e.g., in order to 
address immediate health and welfare impacts); EGs that apply to an 
extraordinary number of disparate designated facilities; or EGs that 
are novel and/or unusually complex. For situations like these, 40 CFR 
60.20a(a)(1) provides that an EG may supersede any aspect of the 
implementing regulations, including the implementation timelines. It is 
within the EPA's discretion to determine whether a proposed change in 
implementation time may be justified within an individual EG based on 
these or other appropriate factors. For EGs that supersede 
implementation timelines, the EPA will, in the EG, both provide a 
justification for the differing timelines and address how the change in 
timeline will impact health and welfare.
1. State Plan Submission Timelines
    This section discusses the amount of time states will have to 
submit plans and plan revisions to the EPA following the publication of 
a final or revised EG in the Federal Register. As described in further 
detail in section III.E of this preamble, under CAA section 111(d), the 
EPA first determines a BSER and the degree of emission limitation for 
designated facilities and promulgates these determinations in an EG. 
CAA section 111(a)(1), 40 CFR 60.22a(b)(5). It is then each state's 
obligation to submit a plan to the EPA which establishes standards of 
performance based on the EG for each designated facility. See CAA 
section 111(d)(1), 40 CFR 60.24a(c). The implementing regulations 
promulgated in 1975 under subpart B provide that states have 9 months 
to submit a state plan after publication of a final EG. 40 CFR 
60.23(a)(1). In 2019, the EPA promulgated subpart Ba and provided 3 
years for states to submit plans or plan revisions for subsequently 
promulgated or revised EGs, consistent with the timelines provided for 
submission of SIPs pursuant to CAA section 110(a)(1). This 3-year 
timeframe was vacated by the D.C. Circuit in the ALA decision, and thus 
currently there is no applicable deadline for state plan submissions 
and revisions required under EGs subject to subpart Ba.
    As laid out in the notice of proposed rulemaking and summarized 
below, in evaluating the appropriate timeline for plan submittal to 
replace the vacated provisions in subpart Ba, the EPA reviewed steps 
that states need to carry out to develop, adopt, and submit a state 
plan to the EPA, and its history in implementing EGs under the timing 
provisions of subpart B. The EPA further evaluated the statutory 
deadlines and processes for relatively comparable state plans under CAA 
section 129, and attainment planning SIPs submitted pursuant CAA 
sections 189(a)(2)(B) and 189(b)(2) for the 2012 National Ambient Air 
Quality Standards (NAAQS) for fine particulate matter 
(PM2.5). 78 FR 3085 (January 15, 2013). Finally, the EPA 
incorporated consideration of the ALA decision addressing expediency in 
implementation of EGs for protection of public health and welfare.
    To develop a CAA section 111(d) state plan, a state must complete a 
series of steps to ensure that the plan will meet all applicable 
requirements. Subpart Ba specifies the elements that must be included 
in a state plan submission (see 40 CFR 60.24a, 60.25a, 60.26a) as well 
as certain processes that a state must undertake in adopting and 
submitting a plan (see 40 CFR 60.23a). In addition to the requirements 
of these implementing regulations, there are also state-specific 
processes applicable to the development and adoption of a state plan, 
including the administrative processes (e.g., permitting processes, 
regulatory development, legislative approval) necessary to develop and 
adopt enforceable standards of performance. State plan development 
generally involves several phases, including providing notice that the 
state agency is considering adopting a rule; taking public comment; and 
approving or adopting a final rule. The process required to formally 
adopt a rule at the state level differs from state to states.\18\
---------------------------------------------------------------------------

    \18\ In many states, the agency must submit its rule to a 
particular independent commission or the legislature for review and 
approval before the rule is finally adopted. Generally, adopted 
rules are filed with a state entity, such as the secretary of state, 
and eventually published in a register and placed into the state's 
administrative code. State law establishes when an adopted rule is 
effective.
---------------------------------------------------------------------------

    As previously mentioned, subpart B provides 9 months for states to 
submit plans after publication of a final EG. The EPA's review of 
state's timeliness for submitting CAA section 111(d) plans under the 9-
month timeline indicated that most states either did not submit plans 
or submitted plans that were substantially late.\19\ The EPA also noted 
that the plans submitted under subpart B were not subject to additional 
requirements for meaningful engagement and consideration of RULOF, 
which may add time to the state development process relative to plans 
developed and submitted under subpart B. For these reasons, the EPA 
found that 9 months is not a reasonable amount of time for most states 
to adequately develop a plan for an EG.
---------------------------------------------------------------------------

    \19\ The EPA reviewed the information available in 40 CFR part 
62. The supporting information reviewed is available at Docket ID 
No. EPA-HQ-OAR-2021-0527. Part 62 codifies the Administrator's 
approval and disapproval of state plans for the control of 
pollutants and facilities under CAA section 111(d), and under CAA 
section 129 as applicable, and the Administrator's promulgation of 
such plans or portions of plans thereof.
---------------------------------------------------------------------------

    To help inform the proposal for the state plan submission deadline, 
the EPA also reviewed CAA section 129's statutory deadline and 
requirements for state plans, and the timeliness and responsiveness of 
states under CAA section 129 EGs. CAA section 129 references CAA 
section 111(d) in many instances, creating considerable overlap in the 
functionality of the programs. The processes for CAA sections 111(d) 
and 129 are similar in that states are required to submit plans to 
implement and enforce the EPA's EGs. However, there are some key 
distinctions between the two programs, most notably that CAA section 
129(b)(2) specifies that state plans be submitted no later than 1 year 
from the promulgation of a corresponding EG, whereas the statute does 
not specify a particular timeline for state plan submissions under CAA 
section 111(d). Moreover, CAA section 129 plans are required by statute 
to be at least as protective as the EPA's EGs, without exception. CAA 
section 129(b)(2). While CAA section 111(d) permits states to take into 
account remaining useful life and other factors to set less stringent 
standards for particular sources. This suggests that the development of 
a CAA section 111(d) plan could involve more complicated analyses than 
a CAA section 129 plan and that a longer timeframe is likely reasonable 
for state plans under CAA section 111(d) than the 1-year timeframe the 
statute provides under CAA section 129.
    Additionally, the EPA found that a considerable number of states 
have not made timely state plan submissions in response to previous CAA 
section 129 EGs. In instances where states submitted CAA section 129 
plans, a significant number of states submitted plans between 14 to 17 
months after the promulgated EG.\20\ This again suggests that states 
will typically need more than

[[Page 80488]]

one year to develop a state plan to implement an EG.
---------------------------------------------------------------------------

    \20\ The EPA reviewed the information available in 40 CFR part 
62. The supporting information reviewed is available at Docket ID 
No. EPA-HQ-OAR-2021-0527. Part 62 codifies the Administrator's 
approval and disapproval of state plans for the control of 
pollutants and facilities under CAA section 111(d), and under CAA 
section 129 as applicable.
---------------------------------------------------------------------------

    In the 2019 promulgation of subpart Ba, the EPA mirrored CAA 
section 110 by giving states 3 years to submit plans. As previously 
described, the D.C. Circuit faulted the EPA for adopting the CAA 
section 110 timelines without accounting for the differences in scale 
and scope between CAA section 110 and 111(d) plans. Therefore, in 
proposing the revised timelines the EPA closely evaluated other 
statutory deadlines and requirements for state implementation plans to 
determine what is feasible for a CAA section 111(d) state plan 
submission timeline. The EPA specifically focused on statutory SIP 
submission deadlines and requirements in the context of attainment 
plans for the 2012 PM2.5. NAAQS under CAA section 189 
because it provided a comparable process. CAA section 189(a)(2)(B) 
requires states to submit attainment planning SIPs within 18 months 
after an area is designated nonattainment and there is a record of 
successful state submittals pursuant to this timeline. The 2012 
PM2.5. NAAQS attainment plans were, in most cases, more 
complicated for states to develop when compared to a typical plan that 
may be required under CAA sections 111(d). For example, attainment 
plans require states to determine how to control a variety of sources, 
based on extensive modeling and analyses, in order to bring a 
nonattainment area into attainment of the PM2.5 NAAQS by a 
specified date. Identification of contributing emission sources and the 
development of effective control strategies can be challenging because 
particulate matter pollution is comprised of both primary emissions and 
secondary particle formation. By contrast, under CAA section 111(d), it 
is clear which designated facilities are subject to a state plan, in 
general what control methods are available for the designated pollutant 
from that facility, and that the standards of performance for these 
sources must reflect the level of stringency for the facility as 
determined by the EG unless a state chooses to account for RULOF.
    Informed by these analyses, the EPA proposed to require that each 
state adopt and submit to the Administrator a plan for the control of 
the designated pollutant(s) to which the EG applies within 15 months of 
publication of a final EG. Some commenters supported the proposed 
timeline based on the need for urgency in achieving the emission 
reductions targeted by an EG. Additionally, some commenters noted that, 
in comparison with NAAQS SIP requirements, states are generally well-
positioned to address the source sectors historically regulated under 
CAA section 111(d) and have access to information about control 
strategies and regulatory approaches for controlling emissions. Most 
commenters on this issue were state agencies or other state-related 
entities that generally expressed the need for a longer state plan 
submittal timeline in order to accommodate state regulatory processes 
associated with plan submittals (i.e., legislative and/or 
administrative state processes), as well as to accommodate technical 
development of the plans and to implement the proposed meaningful 
engagement requirements. Approximately 10 states responded to the EPA's 
request with information about their state processes. The information 
received indicates that states argued that they need anywhere from 15 
months to 36 months to adopt and submit state plans. As discussed 
further below, the EPA is finalizing a state plan submittal timeline of 
18 months. It is doing so after consideration of comments received on 
the proposal and recognizing the need to protect public health and 
welfare. The EPA has determined that 18 months is the appropriate 
timeline for these general implementing regulations; for a generic EG, 
this represents a reasonable balance between providing states 
sufficient time to develop and submit a plan that satisfies the 
applicable requirements and ensuring that the emission reductions 
contemplated in an EG are achieved as expeditiously as practicable. 
Consistent with the existing regulations of subpart Ba, 40 CFR 
60.20a(a)(1), the EPA may supersede this 18-month state plan submittal 
timeline in an individual EG.
    The proposed 15-month submittal timeline was based on the EPA's 
proposed determination that this was a reasonably expeditious deadline 
that would provide states and stakeholders sufficient time to develop 
and submit an approvable state plan. However, based on public comments 
received, we no longer believe that 15 months will provide sufficient 
time to complete the substantive and procedural requirements under 
subpart Ba. For example, the EPA is revising subpart Ba to require that 
states demonstrate meaningful engagement as part of their state plan 
development. While the time needed to conduct meaningful engagement 
will depend highly on the source category, the designated pollutant, 
and the types of impacts associated with designated facilities and 
potential controls, as well as on the pertinent stakeholders under a 
given EG within each state, it is very likely to require additional 
time relative to the existing public notice and hearing requirements 
under CAA section 110 and subpart Ba. We received comments that 15 
months would be insufficient time to identify pertinent stakeholders, 
develop public participation strategies, and conduct outreach and 
engagement. Some commenters also pointed out that adding requirements, 
such as meaningful engagement and RULOF, without a corresponding 
extension of time to develop plans may undermine states' abilities to 
submit timely, approvable plans. While some commenters requested 36 
months to submit state plans, several indicated that a minimum 
timeframe of 18 months would be appropriate for a state plan under a 
generic EG. Given the preponderance of comments suggesting that 15 
months was not a reasonable amount of time to develop an approvable 
state plan and in recognition of the need to promulgate a timeline that 
achieves emission reductions as expeditiously as practicable, the EPA 
believes 18 months is the most reasonable timeline to include in these 
generally applicable implementing regulations.
    The EPA acknowledges that, as commenters asserted, state regulatory 
and legislative processes and resources can vary significantly and 
influence the time needed to develop and submit state plans (e.g., 
legislative procedures and timelines vary by state). Some commenters 
opposed to a shorter state plan submission timeline asserted that they 
need 36 months to complete their administrative and legislative 
processes. However, because the CAA contains numerous, long-standing 
requirements under other programs for states to develop and submit 
plans within 18 months (or fewer),\21\ the EPA believes that states 
should be well positioned to accommodate an 18-month submittal timeline 
for plans under section 111(d). In designing a submittal deadline for 
state plans, it is reasonable to look to what Congress has determined 
are appropriate timelines for SIPs and to assume that states should be 
able to accommodate comparable timelines under CAA section 111(d). 
Indeed, some commenters recommend that the EPA not defer to lengthy 
state administrative processes, and expressed concern that some states 
have adopted, or may adopt, procedures that are longer than necessary 
and that will unnecessarily postpone Federal emission-reduction 
obligations. To this point, extending

[[Page 80489]]

state plan submittal timelines to account for any and all unique state 
procedures would inappropriately delay reductions in emissions that 
have been found under CAA section 111 to endanger health or the 
environment.
---------------------------------------------------------------------------

    \21\ See, e.g., CAA sections 110(k)(5); 129; 179(d)(1); 189.
---------------------------------------------------------------------------

    Some commenters asserted that the ALA decision does not preclude 
the EPA from adopting a 36-month time frame for state plan submittals 
and that the Agency need only justify a longer timelines more fully. 
However, the EPA recognizes that the D.C. Circuit, in ALA, faulted the 
Agency for failing to consider the potential impacts to public health 
and welfare associated with extending planning deadlines. In response, 
the EPA is promulgating a state plan submittal timeline that reflects 
the generally expeditious period of time for states to develop and 
submit a plan per the corresponding emission guidelines that is both 
comprehensive and legally sound. The EPA does not interpret the court's 
direction to require a quantitative measure of impact, but rather 
consideration of the importance of meeting the public health and 
welfare goals when determining appropriate deadlines for implementation 
of regulations under CAA section 111(d). Based on EPA's assessment of 
the time it will take for states to develop and submit plans under 
these general implementing regulations, both in the notice of proposed 
rulemaking and this preamble and after consideration of comments 
received, the EPA has determined that 18 months represents the 
generally expeditious period of time.
    Some commenters stated that reduction of the designated pollutants 
addressed by currently proposed emission guidelines (i.e., GHG) is not 
urgent based on the fraction of global GHG reduced by currently 
proposed emission guidelines, so a longer state plan timeline would be 
justified. The EPA disagrees with the commenters' characterizations of 
the threat posed by elevated concentrations of greenhouse gases in the 
atmosphere. The EPA has determined that greenhouse gas air pollution 
may reasonably be anticipated to endanger public health or welfare \22\ 
and has explained that ``scientific assessments, EPA analyses, and 
documented observed changes in the climate of the planet and of the 
U.S. present clear support regarding the current and future dangers of 
climate change and the importance of GHG emissions mitigation.'' \23\ 
Moreover, subpart Ba applies to any EG promulgated after July 8, 2019, 
not only to the recently proposed EGs addressing GHG emissions from two 
source categories. The EPA regulates source categories, through EGs, 
that emit pollutants the Agency has determined under CAA section 111(d) 
to cause or significantly contribute to an endangerment of public 
health or welfare. Accordingly, consistent with ALA, it is appropriate 
for the EPA to set an expeditious but reasonable schedule in these 
general provisions for state plan development and submission to ensure 
that emission reductions occur in a timely manner.
---------------------------------------------------------------------------

    \22\ See, e.g., 80 FR 64510, 64530 (Oct. 23, 2015).
    \23\ 88 FR 33240, 33252 (May 23, 2023).
---------------------------------------------------------------------------

    Finally, some commenters asserted that if the EPA were to finalize 
the state plan submittal timeline as proposed, the EPA should include a 
mechanism in subpart Ba for states to ask for extensions of the state 
plan submittal deadline. However, as we are providing additional time 
for state plan submittals relative to proposal, we are not providing a 
mechanism for states to request deadline extensions in subpart Ba. 
Additionally, the EPA has the ability to supersede the timelines in 
subpart Ba in individual EGs and will take into account any unique 
considerations that may result in the need for longer or shorter 
timelines on an EG-by-EG basis.
    In summary, while the EPA proposed a 15-month state plan submittal 
timeline, after consideration of comments, the EPA is finalizing 40 CFR 
60.23a(a)(1) to provide an 18-month timeline for the submission of 
state plans following publication in the Federal Register of a final 
EG. The EPA has determined that this is the generally expeditious 
period in which states can create and submit a plan per the EPA's 
corresponding EGs that is both comprehensive and legally sound. In 
considering the appropriate timeline, the EPA has evaluated data from 
previously implemented EGs and the statutory deadlines and data from 
analogous programs (e.g., CAA sections 129 and 189). We have also 
considered comments that some of the requirements the EPA had proposed 
for subpart Ba would require additional time to implement, as well as 
comments asserting that certain states need up to 36 months to complete 
their administrative and legislative processes. While a reasonable 
state plan submittal timeline must provide states sufficient time to 
develop and submit plans that comport with the applicable requirements, 
the EPA also believes that state processes should be able to 
accommodate an 18-month timeline because the CAA already contains 
numerous deadlines that require SIP submissions to be developed and 
submitted to the Agency within 18 or fewer months. Thus, this finalized 
timeline should provide states reasonable time to adopt and submit 
approvable plans, and is also sufficiently expeditious to protect 
against significant adverse impacts to health and welfare resulting 
from foregone emission reductions during the state planning process. 
Providing states sufficient time to develop feasible implementation 
plans for their designated facilities that adequately address public 
health and environmental objectives also ultimately helps ensure more 
timely implementation of an EG, and therefore achievement in actual 
emission reductions, than would an unattainable deadline. Because 18 
months is an expeditious time period, it follows that the EPA has 
appropriately considered the potential impacts to public health and 
welfare associated with this extension of time by providing no more 
time than the states reasonably need to ensure a plan is comprehensive 
and timely.
    The EPA is also finalizing the proposed amendment to 40 CFR 
60.27a(a) replacing the word ``shorten'' with ``amend''. The 
applicability provision at 40 CFR 60.20a(a)(1) states that ``each 
emission guideline may include specific provisions in addition to or 
that supersede requirements of this subpart.'' However, the existing 
provision in 40 CFR 60.27a(a) only provides for the Administrator to 
``shorten the period for submission of any plan or plan revision or 
portion thereof.'' To make these two provisions consistent in light of 
the timelines for plan submission finalized in this action, the EPA is 
replacing the word ``shorten'' with ``amend.'' One commenter opposed 
the amendment stating there is no regulatory certainty for the state in 
state plan submittal if the Administrator can simply change the 
timeline as he deems necessary. However, the appropriate timeline would 
undergo notice and comment rulemaking as the EG is proposed and 
finalized so that states would have sufficient notice of the timeline. 
To the extent the EPA considers deviating from this 18-month timeframe 
in promulgating an EG in the future, the EPA will consider the public 
health and welfare impacts associated with extending the state plan 
submission timeline, consistent with the D.C. Circuit's direction in 
ALA.
    The EPA is also finalizing two amendments to 40 CFR 60.28a(a), 
which addresses plan revisions by the state. First, the EPA is 
finalizing the proposed clarification that meaningful engagement 
requirements apply to any significant plan revision by the state. 
Second, the EPA is finalizing revisions

[[Page 80490]]

to the timeline for state plan revisions required in response to a 
revised emission guideline. At proposal, the EPA indicated in the 
revised regulatory text that it was proposing to shorten the timeline 
for state plan revisions in this specific circumstance from three years 
to 12 months.\24\ The EPA received comments on this proposed revision 
asserting that the same process-related challenges that apply to 
initial state plan submissions, including conducting meaningful 
engagement and RULOF procedures and working through states' 
administrative and legislative processes, also apply to state plan 
revisions. Commenters requested that the EPA extend the timeline for 
state plan revisions in response to revised emission guidelines; one 
commenter specifically requested that the EPA leave it at 36 months. 
However, the EPA anticipates that, in most instances, plan revisions 
required in response to a revised emission guideline would be narrower 
in scope than the initial state plan and would not require states to 
reevaluate standards of performance or conduct significant new 
analysis. For example, the EPA may revise an emission guideline to 
provide for additional or updated monitoring or compliance protocols or 
to clarify applicability provisions. In such instances, the full period 
of time provided for initial state plan development and submission 
would not be necessary.\25\ Thus, the EPA believes it is reasonable to 
set a default timeline for the submission of state plan revisions in 
these general implementing guidelines that is shorter than the timeline 
for initial state plan submission. Because the EPA is providing an 
additional three months for state plan submission in this final rule 
relative to the proposed timeline (18 months versus 15 months), it is 
finalizing a timeline for the submission of state plan revisions in 
response to a revised emission guideline of fifteen months, which is 
also three months longer than the twelve months proposed. Additionally, 
in recognition that some state plan revisions in response to a revised 
emission guideline may in fact be more complex or necessitate 
additional analysis or rulemaking, the EPA is finalizing the provision 
at 40 CFR 60.28a(a) to allow the Agency to determine a different 
timeline for the submission of revised state plans, which it will 
provide in the revised emission guideline.
---------------------------------------------------------------------------

    \24\ 
``Docket_memo_outlining_proposed_changes_to_regulatory_text.pdf,'' 
available at https://www.epa.gov/stationary-sources-air-pollution/adoption-and-submittal-state-plans-designated-facilities-40-cfr, as 
well as Docket ID No. EPA-HQ-OAR-2021-0527-0002.
    \25\ The EPA's response to comments that the state plan 
submission timelines should accommodate every state's unique 
administrative and legislative processes is also relevant here and 
is provided elsewhere in this section of the preamble.
---------------------------------------------------------------------------

2. Timeline for the EPA To Determine Completeness of State Plans
    Once a state plan has been submitted to the EPA, the EPA reviews 
the plan for ``completeness'' to determine whether it includes certain 
elements necessary to ensure that the EPA can substantively evaluate 
the plan. The EPA determines completeness by comparing the state's 
submission against the administrative and technical criteria specified 
in subpart Ba to determine whether the submission contains the 
specified elements (see 40 CFR 60.27a(g)(2) for completeness criteria). 
The timeline to make completeness determinations in the version of 
subpart Ba the EPA promulgated in 2019 mirrored the language for SIPs 
in CAA section 110(k)(1)(B): ``Within 60 days of the Administrator's 
receipt of a plan or plan revision, but no later than 6 months after 
the date, if any, by which a State is required to submit the plan or 
revision, the Administrator shall determine whether the minimum 
criteria [for completeness] have been met.'' Like CAA section 
110(k)(1)(B), subpart Ba also provided that a state plan would be 
deemed complete by operation of law if the EPA had not made an 
affirmative determination by the date 6 months after receipt of the 
plan submission. 40 CFR 60.27a(g)(1).
    After a state plan is deemed complete through either an affirmative 
determination or by operation of law, the EPA will act on the state 
plan submission through notice-and-comment rulemaking. The timeline for 
the EPA to act on a state plan submission runs from the date a 
submission is deemed complete; more on this timeline can be found in 
section III.A.3. of this preamble.
    If a state plan submission does not contain the elements required 
by the completeness criteria, the EPA would find that the state has 
failed to submit a complete plan and notify the state through a letter. 
The determination of incompleteness treats the state as if the state 
has made no submission at all. The determination that a submission is 
incomplete and that the state has failed to submit a plan is 
ministerial in nature.
    As part of the EPA's overall effort to set implementation timelines 
under CAA section 111(d) that are as expeditious as possible, the EPA 
proposed to revise the timing element of the completeness review at 40 
CFR 60.27a(g)(1). In light of the ministerial nature of the 
completeness determination, the EPA proposed a maximum of 60 days from 
receipt of the state plan submission for the EPA to make a 
determination of completeness. The EPA additionally proposed that any 
state plan or plan revision submitted to the EPA that has not received 
a completeness determination within 60 days of receipt, shall on that 
date be deemed, by operation of law, to meet the completeness criteria, 
which will trigger the EPA's obligation to take substantive action on 
the state plan. Sixty days provides an expeditious timeframe for the 
EPA to evaluate state plans for completeness and to notify the states 
of the determination. Because the EPA may be required to evaluate up to 
50 state plans during this period, in addition to plans submitted by 
territories and tribes, the EPA explained at proposal that it did not 
find that this timeframe could reasonably be shortened any further.
    While most commenters supported the 60-day completeness period, 
some commenters expressed concern that a state plan that is 
automatically deemed complete by operation of law as of the allotted 60 
days could cause unnecessary turbulence in state plan implementation if 
the plan is later disapproved by the EPA due to missing information. 
Other commenters noted that if a plan is determined to be incomplete, a 
60-day period will not allow states sufficient time to correct the 
deficiency and submit a complete plan. First, the EPA notes that the 
completeness determination is ministerial in nature and does not affect 
the Agency's subsequent responsibility and authority to substantively 
review a state plan submission against the requirements of the Act and 
applicable regulations, including this subpart Ba and the relevant EG. 
That is, a determination that a state plan is complete does not signify 
that it necessarily satisfies the substantive requirements. The 
commenters fail to explain how deeming a state plan submission complete 
by operation of law, in this case after 60 days, and later finding it 
does not satisfy an applicable requirement is a new phenomenon or would 
cause unnecessary turbulence in state plan implementation. Rather, a 
shorter period for deeming plans complete by operation of law would be 
less disruptive than a longer period in this instance because the EPA 
will complete its substantive evaluation of the plan sooner and the 
state will have notice earlier on of any deficiencies. Additionally, 
because states may submit plan revisions at any time, states may

[[Page 80491]]

work collaboratively with the EPA on any portions of a plan identified 
as being deficient during both the completeness determination period 
and the period for the EPA's substantive review of the plan. Thus, 
again, a shorter completeness determination period that includes a 
cutoff for deeming submissions complete by operation of law merely 
keeps the state plan review process moving expeditiously and does not 
foreclose any state opportunities to correct or supplement submissions 
at any point in the EPA's review process.
    Moreover, the EPA intends to review for completeness as soon as 
possible after submittal. Although the EPA believes that it will be 
able to provide a timely completeness determination for most if not all 
state plan submissions, providing for completeness through operation of 
the law will help ensure that the EPA's action on state plans does not 
significantly delay plan processing or implementation.
    The EPA is therefore finalizing the completeness provision at 40 
CFR 60.27a(g)(1) as proposed. The EPA notes that if the EPA determines 
a plan is incomplete, the EPA is required to promulgate, through 
notice-and-comment rulemaking, a Federal plan. See sections III.A.4. 
and III.B. for the discussion and final amendments associated with the 
timeline and triggers of the Federal Plan respectively. If a state 
submits a plan prior to the state plan submission deadline and the EPA 
also makes a determination that the plan is incomplete prior to that 
deadline, the EPA will treat the state as if the state has made no 
submission at all, but this determination does not yet trigger further 
action by the EPA. Instead, because the state still has an opportunity 
to submit a complete plan before the state plan submission deadline, 
the EPA's authority to promulgate a Federal plan is only triggered if 
the state fails to timely submit a new plan to replace the incomplete 
plan by the state plan deadline.
3. Timeline for the EPA's Action on State Plans
    After a state plan has been determined to be complete or is deemed 
complete by operation of law, CAA section 111(d) provides that the EPA 
must evaluate whether the plan is ``satisfactory''; that is, whether 
the components of the plan meet all the requirements of the statute, 
these implementing regulations, and the corresponding EG. The EPA does 
so by evaluating a plan (or plan revision) to determine whether the 
plan or plan revision is approvable, in part or in whole (see section 
III.D.1. of this preamble for discussion on partial plan approvals), 
through a notice-and-comment rulemaking process. After the EPA proposes 
an action on a state plan submission (e.g., approval, partial approval/
partial disapproval, disapproval) and reviews comments on the proposed 
action, the EPA will finalize its action on the plan. If the EPA 
approves a state plan, the standards of performance and other 
components of that state plan become federally enforceable. If the 
state plan is disapproved, in part or in whole, the EPA is obligated to 
promulgate a Federal plan for designated facilities within the state 
that were covered by the disapproved portions of the plan (see section 
III.A.4. of this preamble below for the EPA's timeline to publish a 
Federal plan).
    Subpart B requires the EPA to take action on applicable state plans 
(e.g., approve or disapprove) within 4 months after the date required 
for submission. 40 CFR 60.27(b). In the development of subpart Ba, the 
EPA contended that 4 months was an inadequate time to review and take 
action on state plans and therefore instead provided a deadline of 12 
months for final action on a state plan (mirroring the maximum time 
permitted under CAA section 110(k)(1)(2) for the EPA's action on 
complete SIPs). 84 FR 32520, July 8, 2019. In the ALA decision, the 
D.C. Circuit vacated this revised timeline in subpart Ba on the basis 
that the EPA did not adequately justify the extended timeframes and did 
not consider the public health and welfare impacts of extending the 
implementation times. As is discussed below, the EPA has in this 
rulemaking closely evaluated the process, steps, and timeframes for the 
EPA to substantively review and act upon each state plan submission 
through a public notice-and-comment rulemaking process. After 
considering the time anticipated to be necessary for generally 
expeditious EPA action on state plans, the EPA again proposed that it 
must take final action on a state plan or plan revision submission 
within 12 months after a plan is determined to be complete or becomes 
complete by operation of law.\26\
---------------------------------------------------------------------------

    \26\ The deadlines for the EPA action under subpart Ba would 
apply to any state plan submission regardless of when it is 
submitted.
---------------------------------------------------------------------------

    In the notice of proposed rulemaking, the EPA explained that the 
first step it takes once a state plan submittal has been deemed 
``complete'' under 40 CFR 60.27a(g) is for an intra-agency workgroup to 
review the plan components to determine whether they conform to the 
applicable regulatory requirements. The workgroup may require a broad 
range of expertise in legal, technical, and policy areas, potentially 
including attorneys, engineers, scientists, economists, air monitoring 
experts, health and welfare analysts, and/or policy analysts from 
across a variety of the EPA programs. After review and coordination, 
the workgroup then develops recommendations for approval or disapproval 
of each plan component and presents them to Agency decision-makers for 
review. Once the Agency completes its internal decision-making process, 
the workgroup proceeds to prepare a written notice of proposed 
rulemaking. The notice of proposed rulemaking contains the EPA's legal, 
policy, and technical bases for its proposed action on a state plan 
submission, which must be thoroughly developed and explained in writing 
to provide clear and concise information and reasoning to support the 
public in understanding the Agency's decision and the justification for 
that decision, and so that the public may provide informed comments on 
the proposal. The EPA may further develop technical support documents 
as record support for the proposal. The draft proposed rulemaking and 
any record support then undergo a multi-layered review process across 
the EPA offices and levels of management before being processed for 
signature. The process to evaluate the state plan, draft a proposed 
action on a CAA section 111(d) state plan, and get the proposed action 
edited, reviewed, and signed typically requires a minimum of between 6 
to 8 months to complete. The signed notice of proposed rulemaking is 
then submitted for publication in the Federal Register, which may 
require several weeks of review and processing prior to publication.
    The publication of the proposed rulemaking triggers the start of a 
public comment period of at least 30 days with possible extension, if 
requested by commenters. Because of the types of sources and pollutants 
regulated under CAA section 111(d), the EPA reasonably anticipates that 
many of its proposed actions on state plans will garner significant 
public interest from individuals, industry, states, and environmental 
and public health advocates. After completion of the comment period, 
the EPA then reviews all comments and determines whether, based on any 
information provided by the comments, it should alter its proposed 
action or further augment the legal, policy, and technical rationales

[[Page 80492]]

supporting that action. Comments received on a proposed action may 
include technical information that was not available to the EPA at the 
time of proposal. In the event technical data are received as part of 
comments on the proposed action, the EPA would then be required to 
review the new data and evaluate whether and how it should affect the 
EPA's proposed conclusions regarding the state plan. If a substantive 
comment is raised that merits reconsideration of the EPA's proposed 
action, the EPA may determine that it is necessary to revise and 
repropose its action on the state plan or it may go to the state for 
more information to help the Agency determine how to proceed.
    Once this review of comments is complete, the workgroup drafts and 
presents updated recommendations for action for internal review and 
consideration by Agency decision-makers. Once the Agency completes its 
internal decision-making process, the workgroup then drafts a notice of 
final rulemaking on the plan submission, which includes responses to 
comments, any necessary record support, and may also include final 
regulatory text. The draft final action is then reviewed by senior 
management and other interested EPA offices within the Agency prior to 
signature of the final rulemaking approving or disapproving, in whole 
or in part, a state plan. It is reasonable to permit at least 4 to 7 
months for evaluation of the comments received, any necessary technical 
analysis, decision-making, and drafting and review of the final action.
    The duration of each step in this deliberative process varies. The 
amount of time the EPA needs to review a state plan submission and the 
time it needs to finalize a notice of proposed rulemaking depends in 
part on the plan's complexity and the nature of the technical, policy, 
and legal issues that it implicates. For example, a state plan 
submission that includes standards of performance for dozens of 
facilities on different compliance schedules would be more complex and 
time consuming to review than a plan that simply establishes standards 
of performance reflecting the presumptive level of stringency for all 
sources. Similarly, the amount of time needed to respond to comments 
and issue a final rulemaking depends in part on the number and type of 
comments received on the EPA's proposed rulemaking. Additionally, the 
EPA reasonably anticipates that it will be required to review multiple 
plan submissions at a given time, and these phases of review for a 
given plan are impacted by the EPA's review of other state plan 
submissions, as the EPA will need to assure its review across multiple 
plans and regional offices is consistent from a legal, technical, and 
policy perspective.
    While some commenters supported 12 months as an expeditious 
timeframe for the EPA review and action on state plan submittals, 
several noted that 12 months may be insufficient. These commenters 
asserted that the EPA must meaningfully evaluate and take action on a 
state plan and a 12-month timeframe may be too short for this process. 
However, as detailed in the discussion above, the EPA has a mapped out 
the time necessary to take action on a generic plan submission and 
believes that 12 months is the most expeditious and therefore the most 
appropriate period to provide for these generally applicable 
implementing regulations. Additionally, the EPA has completed hundreds 
of actions on CAA section 110 SIPs within 12 months over the past 4 
years. Given that the EPA may choose to supersede the requirements of 
subpart Ba as necessary in an individual EG, we believe that providing 
the shortest period here is consistent with considering health and 
welfare impacts by designing timelines to achieve state plan 
implementation as expeditiously as reasonably possible.
    The EPA is therefore finalizing as proposed 40 CFR 60.23a(b) to 
provide that it will take action on a state plan or plan revision 
within 12 months of a determination of a complete plan pursuant to 40 
CFR 60.27a(g). This is a reasonably expeditious timeframe to 
accommodate the EPA action on a state plan or plan revision submission 
and the considerations described above, while ensuring that an EG is 
expeditiously implemented. The process and steps described in this 
action highlight the fact that it would be unreasonable, if not 
impossible, to accomplish all of the steps in a legally and technically 
sound manner within a 4-month timeframe as required under subpart B. 
Particularly, any proposed action by the EPA has to be open for public 
comment for at least 30 days, and therefore the 4-month timeline 
provided in subpart B only gave the EPA 3 months to do the substantive 
work of both the proposed and final actions, including evaluating the 
state plan submission, drafting preamble notices, responding to 
comments, and developing record support at both the proposed and final 
action stages. A 12-month timeframe after a plan is determined to be 
complete more reasonably accommodates the process and steps described 
in this action.\27\
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    \27\ While the EPA would have the discretion to act on a state's 
submission more quickly than 12 months where specific circumstances 
allow (e.g., where there are no public comments on the proposed 
action), the EPA does not believe that it would be reasonably 
possible to act significantly more quickly than 12 months in most 
cases.
---------------------------------------------------------------------------

    As explained at proposal, the EPA recognizes that the court in ALA 
faulted the Agency for failing to consider the potential impacts to 
public health and welfare associated with extending planning deadlines. 
The EPA does not interpret the court's direction to require a 
quantitative measure of impact, but rather consideration of the 
importance of the public health and welfare goals of CAA section 111(d) 
when determining appropriate deadlines. Because 12 months is an 
adequate period of time in which the EPA can both expeditiously act on 
a plan submission and ensure that its action is technically and legally 
sound, it follows that the EPA has appropriately considered the 
potential impacts to public health and welfare associated with this 
extension of time by providing no more time than the EPA reasonably 
needs to ensure a plan submission contains appropriate and protective 
emission reduction measures. If the EPA does not have adequate time to 
evaluate a state plan submission, its ability to ensure the plan 
contains appropriate measures to satisfactorily implement and enforce 
the standards necessary to comply with the EG may be compromised, which 
would in turn compromise the EPA's ability to ensure that the public 
health and welfare objectives of the EG are satisfied. Although several 
commenters noted that the review of some plans may require a more in 
depth analysis, the EPA believes 12 months is a both reasonable and 
expeditious timeframe to evaluate and act on most state plans. 
Accordingly, in order to ensure that the public health and welfare 
objectives of CAA section 111 are timely realized, and consistent with 
the direction in ALA, the EPA does not believe it would be appropriate 
to finalize a timeframe longer than 12 months for the EPA action on 
state plans.
4. Timeline for the EPA To Promulgate a Federal Plan
    CAA section 111(d)(2) provides that the EPA has the same authority 
to prescribe a Federal plan for a state that fails to submit a 
satisfactory plan as it does for promulgating a FIP under CAA section 
110(c). Accordingly, the EPA's obligation to promulgate a Federal plan 
is triggered in three situations: where a state does not submit a plan 
by the plan

[[Page 80493]]

submission deadline; where the EPA determines a portion or all of a 
state plan submission did not meet the completeness criteria and the 
time period for state plan submission has elapsed and, therefore, the 
state is treated as having not submitted a required plan; and where the 
EPA disapproves a state's plan. 40 CFR 60.27a(c). The EPA is finalizing 
as proposed the revisions to 40 CFR 60.27a(c) providing that the Agency 
will promulgate a Federal plan at any time within 12 months of any of 
the triggers in Sec.  60.27a(c)(1) and (2) (see section III.B. of this 
preamble for discussion).\28\
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    \28\ The EPA has discretion to address its obligation to 
promulgate a Federal plan in a variety of ways for states that do 
not have an approved state plan. For example the EPA may initially 
promulgate a single Federal plan that applies to all appropriate 
states and then update that Federal plan as necessary to accommodate 
the inclusion of other states that trigger the need for a Federal 
plan in the future (e.g., a Federal plan that applies to states that 
fail to submit a plan can be updated to include applicability for 
states that later have a plan disapproved); or the EPA may 
promulgate separate Federal plans each time its authority to do so 
has been triggered (e.g., the EPA will promulgate a Federal plan for 
all states that fail to submit a plan and another Federal plan for 
all states that have their plan disapproved).
---------------------------------------------------------------------------

    The EPA is obligated to promulgate a Federal plan for states that 
have not submitted a plan by the submission deadline. Once the 
obligation to promulgate a Federal plan is triggered, it can only be 
tolled by the EPA's approval of a state plan. If a Federal plan is 
promulgated, a state may still submit a plan to replace the Federal 
plan. A Federal plan under CAA section 111(d) is a means to ensure 
timely implementation of EGs, and a state may choose to accept a 
Federal plan for their sources rather than submit a state plan. While 
the EPA encourages states to timely submit plans for EGs, there are no 
sanctions associated with failing to timely submit an approvable plan 
or with the implementation of a Federal plan.\29\
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    \29\ CAA section 179 provides that sanctions should be applied 
in states that fail to submit approvable SIPs for certain specified 
requirements for NAAQS implementation. The EPA has not promulgated 
any similar sanctions provisions governing the submission of state 
plans pursuant to section 111(d).
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    The original implementing regulations in subpart B provided the EPA 
with 6 months to promulgate a Federal plan once its obligation to do so 
was triggered. 40 CFR 60.27(d). When the EPA promulgated subpart Ba in 
2019, it concluded that this amount of time was insufficient and 
consequently extended the time for the EPA to promulgate a Federal plan 
to 24 months, mirroring the timeframe permitted for promulgation of a 
FIP under CAA section 110. 84 FR 32520, July 8, 2019. In the ALA 
decision, the D.C. Circuit vacated this revised timeline in subpart Ba 
on the basis that the EPA did not adequately justify the extended 
timeframe and did not consider the health and welfare impacts of 
extending the implementation timeframe.
    At proposal, the EPA reevaluated the process, steps, and timeframes 
for the EPA to promulgate a Federal plan through a public notice-and-
comment rulemaking process and proposed a 12-month timeframe to 
promulgate a Federal plan once its obligation to do so is 
triggered.\30\ As explained in the notice of proposed rulemaking, a 
Federal plan must meet the requirements of CAA section 111(d) and 
therefore contain the same components as a state plan, namely standards 
of performance for designated facilities and measures that provide for 
the implementation and enforcement of such standards. CAA section 
111(d)(2)(B) also explicitly requires the EPA to consider RULOF in 
promulgating a standard of performance under a Federal plan. 
Additionally, Federal plans containing standards of performance are 
subject to the procedural requirements of CAA section 307(d), such as 
the requirements for proposed rulemaking and opportunity for public 
hearing. CAA section 307(d)(1)(C). The EPA's regulations at 40 CFR 
60.27a implement these various statutory requirements and contain 
general regulatory requirements for the EPA's promulgation of a Federal 
plan. The process, and steps for the EPA to promulgate a Federal plan 
consistent with these applicable requirements is described in the 
following paragraphs.
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    \30\ The EPA reviewed the information available in 40 CFR part 
62 associated with the promulgation of Federal Plans under CAA 
section 111(d). The supporting information reviewed is available at 
Docket ID No. EPA-HQ-OAR-2021-0527. Under the provisions of CAA 
section 111 and subpart B, the EPA promulgated Federal plans for 
municipal solid waste landfills EG 40 CFR part 60, subpart Cc 
(Federal plan codified at 40 CFR part 62, subpart GGG) and municipal 
solid waste landfills EG 40 CFR part 60, subpart Cf (Federal plan 
codified at 40 CFR part 62, subpart OOO).
    The EPA also reviewed information available in 40 CFR part 62 
associated with the promulgation of Federal Plans under CAA 129. The 
supporting information reviewed is available at Docket ID No. EPA-
HQ-OAR-2021-0527. Under the provisions of CAA sections 111 and 129 
and subpart B, the EPA has promulgated Federal plans for large 
municipal waste combustors EG 40 CFR part 60, subpart Cb (Federal 
plan codified at 40 CFR part 62, subpart FFF); small municipal waste 
combustors EG 40 CFR part 60, subpart BBBB (Federal plan codified at 
40 CFR part 62, subpart JJJ); hospital, medical, and infectious 
waste incinerators EG 40 CFR part 60, subpart Ce (Federal plan 
codified at 40 CFR part 62, subpart HHH); commercial and industrial 
solid waste incinerators EG 40 CFR part 60, subpart DDDD (Federal 
plan codified at 40 CFR part 62, subpart III) and sewage sludge 
incinerators EG 40 CFR part 60, subpart MMMM (Federal plan codified 
at 40 CFR part 62, subpart LLL).
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    Once the EPA's obligation to promulgate a Federal plan is 
triggered, the EPA establishes an intra-agency workgroup to develop the 
rulemaking action to address that obligation. The workgroup first 
develops recommendations for the components of the Federal plan to be 
proposed, and on legal, policy, and technical rationales that support 
the recommendations. These components are identified in subpart Ba as 
well as in the corresponding EG and are generally the same as those 
required for a state plan. One of these fundamental components is the 
determination of standards of performance for designated facilities. 
Based on the requirements of CAA sections 111(d) and 111(a)(1), these 
standards must generally reflect the degree of emission limitation 
achievable through application of the BSER as determined by the EPA as 
part of the EG. Depending on the form of the BSER and the degree of 
emission limitation in a particular EG, the EPA may need to do 
additional work to calculate standards of performance that reflect this 
level of stringency. For example, an EG may translate the degree of 
emission limitation into a presumptive standard in the form of 
numerical emission rates, which a Federal plan could simply adopt as 
the requisite standards of performance. However, if an EG provides the 
degree of emission limitation in a form other than presumptive 
numerical standards, and the EPA may need to calculate appropriate 
standards of performance in the context of a Federal plan. Further, CAA 
section 111(d)(2) requires the EPA to consider RULOF for sources in the 
source category in setting standards of performance as part of a 
Federal plan which requires the EPA to identify whether the remaining 
useful lives of relevant designated facilities, among other appropriate 
factors, merit the EPA establishing different standards of performance 
for those facilities. The development of a Federal plan may also 
necessitate that the EPA determine appropriate testing, monitoring, 
reporting, and recordkeeping requirements to implement the standard if 
the EG does not provide presumptive requirements to address those 
aspects of implementation. Further, the EPA will need to consider 
associated compliance times for designated facilities in circumstances 
where they are not provided by an EG, or in cases where a standard of 
performance is adjusted to account for RULOF. There may also be 
situations where IoPs are warranted,

[[Page 80494]]

and the EPA will correspondingly need to identify and determine the 
appropriate IoPs. The development of a Federal plan with these 
components, or of significant revision to a Federal plan, will also 
include elements of meaningful engagement, as finalized in this action 
including revision to section 40 CFR 60.29a and as further described in 
section III.C. of this preamble.
    Once the recommendations for each component are developed, the 
workgroup presents them to Agency decision-makers for review. After the 
Agency completes its internal decision-making process, the workgroup 
proceeds to prepare a written notice of proposed rulemaking. The 
proposal must include the following elements, as required by CAA 
section 307(d)(3): the factual data on which the proposed rulemaking is 
based; the methodology used in obtaining the data and in analyzing the 
data; and the major legal interpretations and policy considerations 
underlying the proposed rulemaking. These elements must be thoroughly 
developed and explained in the proposal to meaningfully provide the 
public adequate information to comment on the proposal. The EPA may 
further develop a technical support document as record support for the 
proposal.
    The draft proposed rulemaking and any record support are then 
reviewed by the relevant EPA offices and processed for signature. The 
signed notice of proposed rulemaking is then submitted for publication 
in the Federal Register. To develop the proposed Federal plan 
rulemaking, establish unique standards for RULOF, allow review of 
materials by senior management, go through an interagency review 
process and have the package signed typically requires a minimum of 
between six to nine months to complete.
    As previously noted, the EPA's promulgation of a Federal plan is 
subject to the requirements of CAA section 307(d), which includes 
providing the public with an opportunity to provide an oral 
presentation at a public hearing. CAA section 307(d)(5). The Federal 
Register Act requires the EPA to provide sufficient notice of a public 
hearing, which (in the absence of a different time specifically 
prescribed by the relevant Act of Congress) is satisfied if the EPA 
provides at least 15 days' notice. 44 U.S.C. 1508. Section 307(d)(5) of 
the CAA further provides that the EPA must keep the record for the 
proposed action open for public comment for 30 days after any public 
hearing for the submission of rebuttal and supplemental information. 
Because the EPA reasonably expects to provide notice of the required 
public hearing at the time its proposed action is published in the 
Federal Register, in order to allow for both a 15-day notice of the 
public hearing and a subsequent 30-day comment period on the open 
record, the EPA should allow for at least 45 days for public comment on 
the notice of proposed action.
    As with state plans, because of the types of sources and pollutants 
regulated under CAA section 111(d), the EPA reasonably anticipates that 
many of its proposed actions on a Federal plan will garner significant 
public interest from individuals, industry, states, and environmental 
and public health advocates. After completion of the comment period, 
the EPA then reviews all comments and determines whether, based on any 
comment, it should alter any components of the proposed Federal plan, 
or further augment the legal, policy, and technical rationales 
supporting that proposed action. Additionally, in the EPA's experience, 
comments may include technical information that was not in front of the 
Agency at the time of proposal. In the event technical data are 
received as part of comments on the proposed action, the EPA would then 
be required to review the new data and evaluate whether and how it 
should affect the EPA's proposed Federal plan. If a substantive comment 
is raised that merits reconsideration of any component in the proposed 
Federal plan, the EPA would need to repropose the plan.
    Once this review of comments is complete, the workgroup drafts and 
presents updated recommendations for internal review and decision 
making. Once the Agency completes its internal decision-making process, 
the workgroup then drafts a notice of final rulemaking, which includes 
responses to comments and any necessary record support, and final 
regulatory text as the Federal plan directly regulates certain 
designated facilities. The draft final action is then reviewed by 
relevant offices within the Agency prior to signature of the final rule 
promulgating the Federal plan. The EPA typically anticipates that the 
process of reviewing comments received, making corresponding changes to 
the rulemaking, and promulgating the final Federal plan to be between 4 
and 8 months.
    The duration of each step in this deliberative process varies. The 
amount of time the EPA needs to develop, propose, and finalize a 
Federal plan depends in part of the plan's complexity and the nature of 
the technical, policy, and legal issues that it implicates. For 
example, some states needing a Federal plan may have thousands, if not 
hundreds of thousands, of designated facilities for which the EPA will 
need to establish standards of performance and implementation measures, 
while other Federal plans may be significantly smaller in scale. 
Similarly, the amount of time needed to respond to comments and issue a 
final rule depends in part on the number and type of comments received 
on the EPA's proposed rulemaking. Additionally, the EPA reasonably 
anticipates that it may need to promulgate a Federal plan for multiple 
states at a given time, which can amplify the amount of time and work 
needed.
    In response to this proposed timeline, several commenters asserted 
that the EPA should provide itself more than the proposed 12 months to 
promulgate a Federal plan, with some commenters noting additional time 
needed for the EPA to provide for meaningful engagement and 
consideration of RULOF. However, based on the assessment as presented 
in the preceding paragraphs, recognizing that much of the evaluation 
needed for promulgating a Federal plan will be performed by the EPA 
during development of the EG, considering the need for expeditious 
implementation of EGs, and noting that RULOF is expected to only be 
needed for certain limited circumstances, the EPA is finalizing the 
requirement that it promulgate a Federal plan within 12 months once its 
obligation to do so is triggered, i.e., either the date required for 
submission of a state plan (for states that fail to submit a complete 
plan) or the date the EPA disapproves a state's plan. As with the other 
timelines in subpart Ba, the EPA may supersede the 12 month timeline 
for a Federal plan as appropriate depending on the circumstances of the 
applicable EG.
    The EPA also recognizes that some commenters stated that the EPA 
need not and should not wait for its Federal plan obligation to be 
``triggered'' to begin developing such a plan. The EPA agrees that 
early development of the Federal plan, where possible before the EPA's 
obligation is formally triggered, could provide the EPA with additional 
time to meet this deadline. The EPA notes that to further streamline 
the timeline associated to the issuance of a Federal plan, the EPA is 
also finalizing the proposed change to the trigger for the EPA's 
obligation and timeline to provide a Federal plan for states that do 
not submit a timely plan. That discussion is found in section III.B. of 
this preamble.

[[Page 80495]]

    Thus, the EPA is finalizing as proposed the revisions to 40 CFR 
60.27a(c) providing that the Agency will promulgate a Federal plan at 
any time within 12 months of any of the triggers in Sec.  60.27a(c)(1) 
and (2). While retaining the authority to supersede this timeline in an 
EG if appropriate, the EPA has determined that 12 months reasonably 
accommodates the amount of time that the EPA needs to undertake the 
process, steps, and the considerations described above, while ensuring 
that an EG is expeditiously implemented. The process and steps 
described earlier that the EPA must be taken in promulgating a Federal 
plan highlight the fact that it would be unreasonable, if not an 
impossibility, to accomplish all of the steps in a legally and 
technically sound manner within a 6-month timeframe as required under 
subpart B.\31\
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    \31\ While the EPA would have the discretion to promulgate a 
Federal plan more quickly than 12 months where specific 
circumstances allow (e.g., where there are no public comments on the 
proposed action), the EPA does not believe that would be reasonably 
possible to act significantly more quickly than 12 months in most 
cases.
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    As with the EPA's finalized timeline to act on state plan 
submissions, 12 months is generally the period of time in which the EPA 
can both expeditiously complete a Federal plan and ensure it is 
technically and legally sound. Therefore, this time period considers 
potential impacts to public health and welfare by giving the EPA a 
reasonably expeditious timeframe to promulgate a Federal plan that 
contains appropriate and protective emission reduction measures. This 
is especially true in the context of a Federal plan, where there is 
otherwise no state plan in place that is adequately protective of 
public health and welfare. If the EPA does not have adequate time to 
promulgate a Federal plan, its ability to ensure the plan contains 
appropriate measures to satisfactorily implement and enforce the 
standards necessary to comply with the EG may be compromised, which 
would in turn compromise the EPA's ability to ensure that the public 
health and welfare objectives of the EG are satisfied.
    The EPA notes that a state may submit a plan to replace a Federal 
plan, even after the state plan submission deadline. However, once the 
EPA's authority and obligation to promulgate a Federal plan has been 
triggered, the act of a state submitting a plan alone does not abrogate 
the EPA's authority or obligatory timeline to promulgate a Federal 
plan. Only an approved state plan can supplant an already promulgated 
Federal plan or abrogate the EPA's responsibility to timely promulgate 
a Federal plan. Where a state submits a late plan, that may have the 
practical effect of concurrent timelines for promulgation of the 
Federal plan and the EPA's action on that late state plan; the EPA is 
not obligated to act on a late state plan prior to promulgating a 
Federal plan (40 CFR 60.27a(d)).
5. Timeline for Increments of Progress (IoPs)
    As part of the EPA's statutory responsibility to determine the 
degree of emission limitation achievable through application of the 
BSER and to include it in an EG, the EPA also determines in an EG ``the 
time within which compliance with standards of performance can be 
achieved.'' 40 CFR 60.22a(b)(5). Accordingly, state plans must include 
both standards of performance for designated facilities and compliance 
schedules for achieving those standards of performance.\32\
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    \32\ ``Each plan shall include standards of performance and 
compliance schedules.'' 40 CFR 60.24a(a).
---------------------------------------------------------------------------

    In 1975, the EPA defined in subpart B ``compliance schedule'' as 
``a legally enforceable schedule specifying a date or dates by which a 
source or category of sources must comply with specific standards of 
performance contained in a plan or with any increments of progress to 
achieve such compliance.'' In subpart B the EPA also defined 
``increments of progress'' as steps to achieve compliance which must be 
taken by an owner or operator of a designated facility including: (1) 
submittal of a final control plan for the designated facility to the 
appropriate air pollution control agency; (2) awarding of contracts for 
emission control systems or for process modifications, or issuance of 
orders for the purchase of component parts to accomplish emission 
control or process modification; (3) initiation of on-site construction 
or installation of emission control equipment or process change; (4) 
completion of on-site construction or installation of emission control 
equipment or process change; and (5) final compliance. The EPA adopted 
these definitions without change when it promulgated subpart Ba in 
2019.
    Subpart B requires that each state plan include emission standards 
and compliance schedules. 40 CFR 60.24a. In addition, subpart B 
specifies in 40 CFR 60.24(e)(1) that any compliance schedule extending 
more than 12 months from the date required for submittal of the plan 
must include legally enforceable increments of progress to achieve 
compliance for each designated facility or category of facilities. 
Unless otherwise specified in the applicable subpart, increments of 
progress must include, where practicable, each increment of progress 
specified in Sec.  60.21(h) and must include such additional increments 
of progress as may be necessary to permit close and effective 
supervision of progress toward final compliance. The provision in 40 
CFR 60.24(e)(1) was amended in 2000.\33\ The 2000 amendments to 40 CFR 
60.24(e)(1) added the words ``Unless otherwise specified in the 
applicable subpart'' to the requirements associated with IoPs. The EPA 
described in the 1999 proposal that the purpose of this amendment was 
to allow the EPA, in a specific subpart, discretion in the number of 
IoPs that a designated facility must meet. Without this amendment 
subpart B required designated facilities to meet all five IoPs 
specified in the IoP definition. In the 1999 proposal the EPA 
recognized that while for some categories of designated facilities the 
five increments are appropriate, all five IoPs may not be necessary to 
ensure compliance for other categories of designated facilities. 
Therefore, EPA proposed and finalized amendments to 40 CFR 60.24(e) to 
allow discretion and flexibility in establishing IoPs for a particular 
subpart.
---------------------------------------------------------------------------

    \33\ 65 FR 76380 (Dec 6, 2000).
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    In promulgating subpart Ba in 2019, the EPA largely carried over 
the requirement of subpart B at 40 CFR 60.24(e)(1) in a new provision 
40 CFR 60.24a(d).\34\ However, to align the trigger of IoPs in 40 CFR 
60.24a(d) to the updated timelines it was finalizing in subpart Ba, in 
2019 the EPA adopted a timeframe trigger for IoPs of 24-months instead 
of the 12-months as in subpart B. Per the finalized 2019 subpart Ba 
provision at 40 CFR 60.24a(d), unless otherwise specified in the 
applicable subpart, any compliance schedule extending more than 24 
months from the date required for submittal of the plan must include 
legally enforceable IoPs to achieve compliance for each designated 
facility or category of facilities. As discussed previously, the D.C. 
Circuit vacated the extended implementation timelines in subpart Ba, 
including the 24-months timeline trigger for IoPs in 40 CFR 
60.24a(d).\35\
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    \34\ In promulgating Ba in 2019, the EPA specified that for 
``For those provisions that are being carried over from the existing 
implementing regulations into the new implementing regulations, the 
EPA is not intending to substantively change those provisions from 
their original promulgation and continues to rely on the record 
under which they were promulgated.'' 84 FR 32520 (July 8, 2019).
    \35\ Petitioners did not challenge, and the court did not vacate 
in ALA, the substantive requirement for or definition of increments 
of progress.

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[[Page 80496]]

    To address the vacated timeline trigger of IoPs in 40 CFR 
60.24a(d), the EPA proposed in 2022 that, unless otherwise specified in 
the applicable subpart, any compliance schedule extending more than 16 
months from the date required for submittal of the plan must include 
legally enforceable IoPs to achieve compliance for each designated 
facility or category of facilities. The proposed 16-month trigger for 
IoPs overlapped with the EPA's proposed 60-day completeness review 
following a state plan submittal and the proposed 12-month period for 
the EPA to review and take action on the state's plan and would have 
further provided a 2-month buffer after the timeline for the EPA's 
action on a state plan (occurring no later than 14 months after the 
plan submission deadline under these general implementing regulations). 
In the 2022 proposal the EPA recognized the proposed 16-month timeframe 
trigger for IoPs provided a 2-month time buffer between the EPA's 
action on a state plan and the trigger of IoPs. As proposed, this 2-
months buffer was less than both the 8 months previously provided by 
subpart B and the 6-month buffer provided by the vacated subpart Ba 
timeline.
    In response to the proposed 16-month IoPs timeframe trigger, 
several commenters asserted the proposed 2-month buffer from the time 
of the EPA's action on a state plan to the trigger of IoPs is not 
practically workable. Some commenters argued that, assuming that there 
could be a required increment of progress right after the 16-months 
trigger and the EPA has 14 months to take final action on a state plan, 
the designated facilities would have only two months to comply with the 
requirement after it becomes federally enforceable. Other commenters 
similarly noted that if final compliance was required just after the 
16-month trigger, designated facilities would similarly have only two 
months to complete any IoPs. The commenters explained that it is unduly 
burdensome for sources to expend resources on developing hypothetical 
final control plans and committing resources to construction projects 
that may ultimately be inconsistent with the EPA's action on a state 
plan. Several commenters that opposed the 16-months proposed timeframe 
trigger for IoPs suggested that the EPA extend the trigger to more than 
24-months, consistent with the previously vacated subpart Ba. Some 
commenters argued that 24 months is the minimum time necessary to 
develop control strategies, design plans, procure construction 
materials and/or equipment, and complete the installations often 
necessary for compliance. Other commenters suggested that a 10-month 
buffer from the EPA action on a state plan to the trigger for IoPs 
would also be acceptable and even preferred, should the EPA miss its 
approval deadlines.
    After consideration of comments and accounting for the discretion 
that EPA has in establishing IoPs in a particular EG, the EPA is 
extending the buffer associated with the trigger of IoPs from 2 months 
to 6 months, so that, unless otherwise specified in the applicable 
subpart, any compliance schedule extending more than 20 months from the 
date required for submittal of the plan must include legally 
enforceable IoPs to achieve compliance for each designated facility or 
category of facilities.
    The EPA emphasizes that the timeline for the trigger for IoPs 
merely signals when the gap between state plan submission and final 
compliance is long enough that the EPA must consider whether IoPs are 
necessary. It is not the case that any EG with a final compliance date 
after the trigger for consideration of IoPs will necessarily require 
all of the increments listed in 40 CFR 60.21a(h). The EPA is required, 
per 40 CFR 60.22a(b)(4), to include within an EG ``[i]ncremental 
periods of time normally expected to be necessary for the design, 
installation, and startup of identified control systems.'' These 
incremental periods are determined within an EG through notice and 
comment rulemaking, providing an opportunity for appropriate 
consideration of the reasonable time needed for the designated 
facilities to meet the requirements associated with the pertinent 
standards of performance. As provided by subpart Ba, the EPA will 
determine in an individual EG whether IoPs are needed to achieve final 
compliance with the standards of performance and, if increments are 
needed, how many and the timeframes associated with compliance of such 
IoPs. However, the EPA also believes that the trigger requirement for 
IoPs should attach to plans that contain compliance periods that are 
longer than the period provided for the EPA's review of such plans and 
in addition provide a reasonable buffer after the EPA has acted on such 
plans so that designated facilities could reasonably comply with 
required increments. After further consideration, the EPA believes that 
a default 2-month buffer between an EPA action on a state plan and a 
hypothetical compliance deadline for a full set of IoPs is not 
generally sufficient.
    In 2019, the EPA promulgated a trigger for IoPs of 24-months given 
that it was finalizing a period of up to 18 months for its action on 
state plans (i.e., 12 months from the determination that a state plan 
submission is complete, which could occur up to six months after 
receipt of the state plan). The 24-month period would have provided a 
6-month buffer for designated sources to comply with any IoPs after the 
EPA acted on state plans. In this action, the EPA is finalizing a 
trigger for consideration of IoPs that provides the same buffer 
provided by the EPA in the 2019 vacated increment of progress timeline 
trigger. The EPA believes a 6-month buffer is generally needed to 
appropriately balance ensuring designated facilities control emissions 
of harmful pollutants as expeditiously as reasonably possible with the 
need for designated facilities to have reasonable certainty regarding 
their federally enforceable regulatory compliance obligations with 
sufficient time before those obligations are due. In addition, the EPA 
determines that the 6-months buffer provides a reasonable time to come 
into compliance with any potential increment of progress when 
compliance date that extends more than 20 months from the date required 
for submittal of the plan. Per the EPA's assessment of the comments and 
in light of the ALA court decision, the EPA determines that a 6-month 
timeframe buffer before the trigger for requirements associated with 
IoPs provides is the most reasonable expeditious period of time 
associated with the requirements for IoPs in 40 CFR 60.24a(d). While 
some commenters argued more time is necessary to develop control 
strategies, design plans, procure construction materials and/or 
equipment, and complete the installations often necessary for 
compliance, the final requirements in subpart Ba does not express the 
EPA's intent to require that states require designated facilities to 
complete all potential IoPs in a 6-month period.
    Several commenters also urged the EPA to link the timelines for 
IoPs to the date on which the EPA takes final action on a state plan, 
instead of with the state plan submittal deadline. However, given that 
there will typically be a single final compliance date specified in an 
EG but the dates on which the EPA takes final action on individual 
states plans are likely to be many and varied based on, inter alia, 
when each state plan was submitted to the Agency, such an approach 
would create unnecessary confusion about whether IoPs must be

[[Page 80497]]

implemented and potentially uneven application of the requirement for 
state plans to include IoPs. It could also create a perverse incentive 
for states to delay submission of their state plans. Additionally, the 
timeline for IoPs initiates from the state plan submittal deadline 
because it is the earliest instance when all standards of performance 
in all timely state plans will be enforceable. It is a requirement of 
state plans, when submitted, to be enforceable at the state level and 
thus all designated facilities subject to a standard of performance in 
a state plan will have assurance of their requirements at the state 
level and can start planning for compliance while the EPA reviews and 
acts on the state plan.
    The timeline for IoPs finalized in this action will ensure 
standards of performance are implemented as expeditiously as possible 
so that the intended emission reductions are achieved, and the public 
health and welfare are protected.

B. Federal Plan Authority and Timeline Upon Failure To Submit a Plan

    CAA section 111(d)(2)(A) provides that the EPA has the same 
authority ``to prescribe a plan for a State in cases where the State 
fails to submit a satisfactory plan as he would have under section 
7410(c) of this title in the case of failure to submit an 
implementation plan.'' The original implementing regulations in subpart 
B provide that the EPA is to ``promptly prepare and publish proposed 
regulations setting for a plan, or portion thereof, for a State if:'' a 
state fails to submit a plan within the time prescribed, the state 
fails to submit a plan revision within the time prescribed or the 
Administrator disapproves a state plan or plan revision or any portion 
thereof. 40 CFR 60.27(c). Subpart B further requires the EPA to 
promulgate the plan proposed under paragraph (c) ``within six months 
after the date required for submission of a plan or plan revision . . . 
unless, prior to such promulgation, the State has adopted and submitted 
a plan or plan revision which the Administrator determines to be 
approvable.'' 40 CFR 60.27(d).
    In promulgating subpart Ba in 2019, the EPA incorporated language 
in the provisions associated with the Actions by the Administrator in 
40 CFR 60.27a(c) from CAA sections 110(c)(1)(A) and 110(k)(1)(B) 
addressing the circumstances which trigger the EPA's authority under 
CAA section 111(d)(2) for promulgating a Federal plan. Specifically, in 
2019 the EPA adopted language at 40 CFR 60.27a(c)(1) that requires the 
EPA to promulgate a Federal plan after it ``[f]inds that a state fails 
to submit a required plan or plan revision or finds that the plan or 
plan revision does not satisfy the minimum criteria under'' 40 CFR 
60.27a(g), i.e., the completeness criteria (emphasis added). Pursuant 
to the amendments being finalized in this action, the EPA will be 
required, under 40 CFR 60.27a(g), to determine whether completeness 
criteria have been met no later than 60 days after the date by which a 
state is required to submit a plan (see section III.A.2. of this 
preamble). These provisions under subpart Ba taken together would mean 
that, no later than 60 days after the state plan submission deadline 
has passed, the EPA must make a finding (often referred to as a 
``finding of failure to submit'') as to whether any states have failed 
to submit a plan that meets the completeness criteria, and such finding 
is what triggers the EPA's obligation and timeline to promulgate a 
Federal plan.\36\
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    \36\ Note that this procedure does not address circumstances 
when the EPA promulgates a Federal plan for states whose plan is 
disapproved. In these circumstances, the state has submitted a plan 
so no finding of failure to submit is issued. The EPA's obligation 
and timeline to promulgate a Federal plan in this instance arises 
from the EPA's disapproval based on its conclusion that the state 
plan submission was unsatisfactory.
---------------------------------------------------------------------------

    At proposal, the EPA acknowledged that in the CAA section 110 
context, it has not always timely met its obligation to issue a finding 
of failure to submit, which in turn delays the timing for when the EPA 
promulgates a FIP to achieve the necessary emission reductions. 
Accordingly, the EPA proposed to streamline the process in the subpart 
Ba context to ensure that the emission reductions anticipated by the EG 
are realized in a timely way through the promulgation of any necessary 
Federal plan. In particular, the EPA proposed revisions to 40 CFR 
60.27a(c)(1) consistent with the framework and requirements that have 
been effective in subpart B since 1975. As proposed the Administrator 
would issue a Federal plan if a state fails to submit a plan within the 
time prescribed without requiring the EPA to affirmatively issue a 
finding of failure to submit before the EPA's obligation to issue a 
Federal plan is triggered.
    As explained in the notice of proposed rulemaking, as part of 
evaluating ways to streamline the steps leading to promulgation of a 
final Federal plan, the EPA considered the value and role of issuing 
findings of failure to submit in this process. A finding of failure to 
submit was intended to serve three purposes under subpart Ba, 
consistent with its purpose under CAA section 110: to notify the public 
of the status of state plan submissions (i.e., providing transparency 
to the process); to notify states that the EPA has not received a plan; 
and to formally start the clock for the EPA to promulgate a Federal 
plan. While these concepts may have some utility as part of the overall 
Federal plan development and implementation process, the EPA finds that 
in the CAA section 111(d) context there is minimal value in coupling 
the notification aspects of a finding of failure with the initiation of 
the clock for the EPA to promulgate a Federal plan. These aspects are 
not inextricably linked to one another in that nothing about a formal 
finding of failure to submit substantively informs the development of a 
Federal plan; the EPA has the information it needs to know which states 
have and have not submitted complete plans. By decoupling the timeline 
from the finding of failure to submit, the EPA's obligation to 
promulgate a Federal plan can be triggered without the interim step and 
potential lag associated with issuing a formal finding of failure to 
submit notification. By removing this interim process, the EPA will be 
required to promulgate the Federal plan more expeditiously, and, in 
turn, overall implementation of the corresponding EG will be timelier. 
Finalizing this amendment is also consistent with the spirit of the ALA 
decision, where the D.C. Circuit emphasized the need for implementation 
timelines that consider potential impacts on public health and welfare. 
By expeditiously and efficiently promulgating a Federal plan and by 
removing an interim step of a finding of failure, the EPA is further 
addressing the potential impacts of implementation times on health and 
welfare.
    Some commenters requested that the EPA retain a separate ``finding 
of failure to submit'' action as the trigger for starting the timeline 
on a Federal plan. They note that the ``finding of failure'' provides 
notification to the states, regulated community, and public of the 
failure, as state submissions can be difficult to track. Commenters 
also note that the need to first provide the finding also provides 
additional time for the states to submit plans or revisions. One 
commenter noted that the EPA should retain the ``finding of failure to 
submit'' procedure and avoid establishing automatic deadlines for 
itself on a schedule that, based on past experience, it is almost 
certain to miss.
    First, the EPA notes that where a state has failed to timely submit 
a state plan, the absence of a state plan submission should be easy to 
track for the state,

[[Page 80498]]

regulated community, and public; many, if not all, states maintain 
public websites on which they document their submissions to the EPA. 
The EPA expects that notification and tracking capabilities will also 
generally be much improved through the use of electronic submittal (see 
section III.F. of this preamble) and increasing public access to online 
information.
    Second, the EPA stresses that the purpose of using a finding of 
failure to submit as the trigger for Federal plan development was not 
to give states time to develop and submit their state plans in excess 
of the regulatorily allotted timeframes. In this action, the Agency is 
finalizing timeframes for state plan submissions that are reasonably 
achievable and that may be superseded where necessary. Decoupling the 
finding of failure to submit and the trigger of state plan development 
should therefore not impact states' abilities to develop and submit 
satisfactory state plans. States always have the ability to submit 
state plans and state plan revisions at any time. Additionally, while 
the EPA recognizes that it has not always provided timely Federal 
plans, the Agency does not believe that changing the starting point for 
its Federal plan clock from a finding of failure to submit to the day 
after state plan submission are due will have an appreciable impact on 
its ability to do so. Notably, the trigger for its timeline will not 
change the length of time the EPA has to promulgate a plan. While the 
commenter implies that the EPA would use the time before it has made a 
finding of failure to submit to start working on a Federal plan, it is 
not reasonable to assume that the Agency is in a position to start 
developing such a plan before it has had a chance to determine if a 
state plan is incomplete. Therefore, the EPA is finalizing its proposed 
approach of removing from subpart Ba a finding of failure to submit as 
the trigger for starting the timeline for a Federal plan. The approach 
being finalized in subpart Ba is consistent with the framework and 
requirements that have been effective in subpart B since 1975. The 
regulatory text at 40 CFR 60.27a(c)(1) is being revised slightly 
relative to proposal to clarify that the 12-month clock starts running 
the day after the state plan submission deadline for instances in which 
a state fails to submit a plan or plan revision by that deadline, and 
the day after state plan submissions would be deemed complete by 
operation of law (i.e., 60 days after the state plan submission 
deadline) for instances in which a state plan has been submitted but 
deemed incomplete.\37\ These revisions merely clarify the EPA's intent 
at proposal to ensure that all states and stakeholders have a clear 
understanding of the timeline for promulgation of a Federal plan. As 
discussed in section III.A.4. of this preamble, the EPA is finalizing 
the requirement that it will have 12 months from the state plan 
deadline to promulgate a Federal plan for states that do not submit a 
plan. Note, the EPA is also finalizing a deadline of 12 months to 
promulgate a Federal plan for states whose plans are disapproved, but 
in those instances the EPA's obligation and timeline to provide a 
Federal plan are triggered off of its disapproval of a state plan.
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    \37\ As discussed in section III.A.2., if a state submits a plan 
but that submission does not contain the elements required by the 
completeness criteria, the EPA would find that the state has failed 
to submit a complete plan and notify the state through a letter. 
That letter is for notification only and, although the EPA intends 
to issue such letters expeditiously, it does not start the clock for 
a Federal plan.
---------------------------------------------------------------------------

    The EPA notes that this amendment to subpart Ba does not affect the 
EPA's obligation under CAA section 110(c) to promulgate a FIP within 2 
years of making a finding that a state has failed to submit a complete 
SIP. In the case of the CAA section 110, the obligation for the EPA to 
first make a finding of failure to submit is derived from the statute, 
whereas nothing in CAA section 111(d) obligates the EPA to make such a 
finding before promulgating a Federal plan. CAA section 111(d)(1) 
directs the EPA to promulgate a process ``similar'' to that of CAA 
section 110, rather than a process that is identical. Therefore, the 
fact that a finding of failure to submit serves as the legal predicate 
for the EPA's obligation to issue a FIP under CAA section 110 does not 
mean that the EPA is also required to treat such a finding as a legal 
predicate for a Federal plan under CAA section 111(d).
    In summary, while recognizing that a finding of failure to submit 
can have value in notifying states and the public of the status of 
plans, the EPA does not find that it is integral to the process of 
promulgating a Federal plan for states that do not submit plans. 
Further, the requirement for the EPA to issue a finding of failure can 
result in significant unwarranted delays in EG implementation. The EPA 
is therefore finalizing the proposed amendment that this finding will 
no longer be the event that triggers the timeline for the EPA's 
issuance of a Federal plan. 40 CFR 60.27a(c)(1). While the EPA will not 
publish a formal finding of failure to submit in the Federal Register, 
the Agency will notify the states and the public of a failure to submit 
expeditiously following the state plan submission deadline or deadline 
for EPA determinations of completeness, as applicable. Additionally, 
the EPA notes that the completeness criteria in 40 CFR 60.27a(g) were 
promulgated in 2019, 84 FR 32520, 32578 (July 8, 2019), and, while the 
EPA is removing finding of failure to submit as the trigger for 
promulgation of a Federal rule, it emphasizes that states may have 
discussions with the EPA and submit revised state plans at any point. 
That is, there remains within this framework ample opportunity for 
iterative state plan development.
    The regulatory provision at 40 CFR 60.27a(c)(1), as finalized, is 
consistent with the requirement that applies regarding the EPA's 
issuance of a Federal plan under subpart B. In subpart B (i.e., 
applicable to implementing regulations for CAA section 111(d) EGs 
promulgated on or prior to July 8, 2019, and currently applicable 
implementing regulations for CAA section 129 EGs), the EPA's obligation 
to promulgate a Federal plan is triggered by the state plan submission 
deadline.

C. Outreach and Meaningful Engagement

    The fundamental purpose of CAA section 111 is to reduce emissions 
from certain stationary sources that cause or significantly contribute 
to air pollution which may reasonably be anticipated to endanger public 
health or welfare. Therefore, a key consideration in the state's 
development of a state plan, in any significant plan revision,\38\ and 
in the EPA's development of a Federal plan or significant plan 
revision, pursuant to an EG promulgated under CAA section 111(d) is the 
potential impact of the proposed plan requirements on public health and 
welfare. A robust and meaningful public participation process is 
critical to ensuring that the full range of these impacts are 
understood and considered.
---------------------------------------------------------------------------

    \38\ A significant state plan revision includes, but is not 
limited to, any revision to standards of performance or to measures 
that provide for the implementation or enforcement of such 
standards.
---------------------------------------------------------------------------

    States often rely primarily on public hearings as the foundation of 
their public engagement in their state plan development process because 
a public hearing has always been explicitly required pursuant to the 
applicable regulations. The existing provisions in subpart Ba (40 CFR 
60.23a(c) through (f)) detail the public participation requirements 
associated with the development of a state plan. Per these implementing 
regulations, states must

[[Page 80499]]

provide certain notice of, and conduct one or more public hearings on, 
their state plan before such plan is adopted and submitted to the EPA 
for review and action.\39\ The EPA is not reopening these basic and 
long-standing public hearing requirements in this rulemaking. However, 
as explained in the notice of proposed rulemaking,\40\ robust and 
meaningful public involvement in the development of a plan should 
sometimes go beyond the minimum requirement to hold a public hearing 
depending on who may be most affected by and vulnerable to the impacts 
being addressed by the plan. Because the CAA section 111(d) program 
addresses existing facilities, some of which may be decades old, it is 
possible that impacted communities may not have had a voice in the 
process when the source was originally constructed, or previous 
outreach may have focused largely on engaging the industry. The EPA 
proposed amendments to 40 CFR part 60, subpart Ba, were intended to 
strengthen the public participation provisions and ensure that all 
affected members of the public, not just a particular subset, have an 
opportunity to participate in the pollution control planning process by 
requiring meaningful engagement with pertinent stakeholders in the 
state's development of a state plan, in any significant plan revision, 
and in the EPA's development of a Federal plan pursuant to an EG 
promulgated under CAA section 111(d).
---------------------------------------------------------------------------

    \39\ States may cancel a public hearing if no request for one is 
received during the required notification period. 40 CFR 60.23a(e).
    \40\ 87 FR 79176, 79190-92 (Dec. 23, 2022).
---------------------------------------------------------------------------

    The EPA proposed to add meaningful engagement with pertinent 
stakeholders in 40 CFR 60.23a(i) and 60.27a(f) and add the definition 
of meaningful engagement and of pertinent stakeholders in 40 CFR 
60.21a. The EPA proposed to define meaningful engagement as it applies 
to this subpart as timely engagement with pertinent stakeholder 
representation in the plan development or plan revision process. Such 
engagement must not be disproportionate nor favor certain stakeholders. 
It must include the development of public participation strategies to 
overcome linguistic, cultural, institutional, geographic, and other 
barriers to participation to assure pertinent stakeholder 
representation, recognizing that diverse constituencies may be present 
within any particular stakeholder community. It must include early 
outreach, sharing information, and soliciting input on the state plan. 
The EPA also proposed to evaluate the approvability of state plans 
based on the components of the meaningful engagement definition.
    The EPA proposed that pertinent stakeholders ``. . . include, but 
are not limited to, industry, small businesses, and communities most 
affected by and vulnerable to the impacts of the plan or plan 
revision.'' Additionally, to ensure that a robust and meaningful public 
engagement process occurs as the states develop their CAA section 
111(d) plans, the EPA proposed to amend the requirements in 40 CFR 
60.27a(g) to include, as part of the completeness criteria, the 
requirement for states to demonstrate in their plan submittal how they 
provided meaningful engagement with the pertinent stakeholders. The 
state would be required to provide, in their plan submittal: (1) a list 
of the pertinent stakeholders identified by the state; (2) a summary of 
engagement conducted; and (3) a summary of the stakeholder input 
received.
    Most of the comments received on the proposed meaningful engagement 
requirements and proposed definitions were supportive of including 
meaningful engagement in the development of the state plans. Several 
commenters stated that they supported the inclusion of environmental 
justice considerations in Federal programs, including requirements for 
meaningful engagement. In particular, one commenter stated that 
outreach and meaningful engagement with stakeholders, specifically 
including communities most affected by and vulnerable to the pollution 
that would be reduced by a state plan, is an important and overdue step 
to ensuring that impacted communities have a voice in a process that 
directly impacts their health and welfare. While several commentors 
affirmed the EPA's authority to require meaningful engagement, some 
commenters said that the EPA lacks such authority. One of the 
commenters argued that the EPA lacks authority to require consideration 
of public health and welfare under CAA section 111(d) because CAA 
section 111 was devised as a technology-based approach to controlling 
emissions from stationary sources, not one predicated on the setting of 
standards directly and exclusively based on public health and welfare 
needs. One of the commenters stated the EPA lacks the authority to pass 
judgment on state plans submitted pursuant to CAA section 111(d) based 
on public engagement and argued that the only statutory requirement in 
CAA section 110 (which 111(d) cross-references) is the requirement that 
states provide ``reasonable notice and public hearings'' prior to 
adoption of a state plan.
    Several commenters supported the EPA's definition of meaningful 
engagement and the proposed meaningful engagement requirement. 
Additionally, some comments supported the state plan approvability 
requirements for meaningful engagement and recommended that the EPA 
also require an accounting of what states have done with stakeholder 
input and how that input was used or not used in their state plan.
    Several commenters expressed the need for additional resources in 
order to conduct meaningful engagement, both for states and 
communities. Some of the comments stated that the EPA needs to consider 
how these increased requirements may strain already limited state 
resources. One commenter said that resources needed to fulfill the 
requirements for meaningful engagement, including costs associated with 
identifying and contacting stakeholders, renting of rooms or spaces for 
multiple public meetings, travel, and associated staff time, will be 
significant and burdensome to states.
    There were several comments requesting clarification on the 
definition of meaningful engagement, and on the proposed approvability 
requirements for meaningful engagement. Some commenters requested that 
the rule provide more clarity on what states need to do for meaningful 
engagement and provide a clear path for states to develop an approvable 
meaningful engagement demonstration. Similarly, other commenters 
recommended the EPA establish a more detailed definition and provide 
examples of best practices for states to follow in implementing 
meaningful engagement, particularly with vulnerable communities, and 
further clarify what is meant by meaningful engagement with pertinent 
stakeholders. Some commenters cited lack of clarity in expressing their 
concern with meaningful engagement being a requirement for state plan 
approvability.
    Based on comments received, the EPA has revised the proposed 
definition of meaningful engagement and is finalizing revisions that 
are flexible enough to serve the unique needs of states and their 
stakeholders, rather than relying on the more prescriptive approach of 
the proposal. The EPA recognizes that states will generally be in the 
best position to understand how to meaningfully engage pertinent 
stakeholders within their borders as they develop state plans. The EPA 
also believes that states and the Federal Government may learn from 
each

[[Page 80500]]

other's efforts to meaningfully engage pertinent stakeholders. The EPA 
further recognizes that appropriate approaches to meaningful 
engagement, as well as the time and resources needed, will be highly 
dependent on characteristics of the source category--such as the number 
and location of designated facilities--as well as on the type of health 
or environmental impacts of the emissions addressed by an EG. 
Additionally, as noted by a number of commenters, states are highly 
diverse in, among other things, their local conditions, resources, and 
established practices of engagement. Also as noted by commenters, 
vulnerable communities are highly diverse in, among other things, their 
technical capacities, access to resources for meaningful participation 
(e.g., geographic distribution, transportation, childcare), languages, 
and available representation.
    For these reasons, rather than finalizing prescriptive substantive 
requirements for how states should conduct meaningful engagement, the 
EPA is requiring in subpart Ba that states, in their state plan 
submissions or significant plan revisions, describe the efforts they 
undertook to meaningfully engage pertinent stakeholders, what input 
they received from stakeholders, and how that input was used or not 
used in their state plan. The EPA will also include this information 
when promulgating Federal plans or significant plan revisions. In 
addition, the EPA is describing some current best practices for 
meaningful engagement in this preamble that states may consider, that 
and which the Agency expects will continue to develop as states 
experiment with different types of meaningful engagement and share 
their experiences through state plans.
    Consistent with these changes, the EPA is finalizing the definition 
of meaningful engagement, as it applies to subpart Ba, as follows: ``. 
. . timely engagement with pertinent stakeholders and/or their 
representatives in the plan development or plan revision process. Such 
engagement should not be disproportionate in favor of certain 
stakeholders and should be informed by available best practices.'' 
States should therefore make a good faith effort to ensure that they 
are engaging in a proportionate manner with all pertinent stakeholders. 
The EPA is also finalizing, as proposed, a definition of ``pertinent 
stakeholders.'' Pertinent stakeholders ``include, but are not limited 
to, industry, small business, and communities most affected by and/or 
vulnerable to the impacts of the plan or plan revision.'' Finally, the 
EPA is including in subpart Ba the three proposed completeness criteria 
requirements for meaningful engagement at 40 CFR 60.27a(g)(2)(ix) and 
adding a fourth completeness criterion, which will require state to 
include in their plans a description of how stakeholder input was 
considered in the development of the state plan or plan revisions.
    The EPA expects that the finalized approach to meaningful 
engagement in state plans will provide the flexibility needed to allow 
states to address specific and unique issues in their states and to 
appropriately communicate with and respond to their stakeholders during 
the notice and comment process. As revised, the meaningful engagement 
component finalized here strengthens the framework for public 
participation in state plan development, a long-standing cornerstone of 
the cooperative federalism structures of CAA sections 110 and 111(d). 
The meaningful engagement component finalized here is intended to 
promote equitable opportunities to participate in the planning process 
for all stakeholders, as opposed to dictating a specific approach or 
set of practices that constitute meaningful engagement.
    To support the goals outlined above, and in response to comments 
received, the EPA is finalizing the proposed completeness criteria that 
require documentation of meaningful engagement, including adding a 
fourth completeness criterion, but the EPA is not finalizing specific 
requirements for what types of outreach meaningful engagement must 
include in subpart Ba. The fourth completeness criterion will require 
states to include a description of how stakeholder input from the 
meaningful engagement process was considered in the development of the 
plan, which the EPA expects will both bolster accountability to 
stakeholders and assist states in ensuring that their meaningful 
engagement processes are additive to the public hearing and 
notification processes which has always been required under subpart Ba. 
See 40 CFR 60.27a(g)(1)(ix). While the EPA finds that the requirements 
finalized in this action are sufficient and appropriate for the general 
CAA section 111(d) implementing regulations, the EPA may provide 
additional guidance pertaining to meaningful engagement in specific 
EGs.
    While the EPA is revising the definition of meaningful engagement 
relative to proposal, the definition of pertinent stakeholders is being 
finalized as proposed. Pertinent stakeholders include, among other 
stakeholders, industry, small business, and communities--in particular, 
communities who are most affected by and vulnerable to the health or 
environmental impacts of pollution from the designated facilities 
addressed by the plan or plan revision. Increased vulnerability of 
communities may be attributable to, among other reasons, an 
accumulation of negative environmental, health, economic, or social 
conditions within these populations or communities, and a lack of 
positive conditions. Examples of such communities have historically 
included, but are not limited to, communities of color (often referred 
to as ``minority'' communities), low-income communities, Tribal and 
indigenous populations, and communities in the United States that 
potentially experience disproportionate health or environmental harms 
and risks as a result of greater vulnerability and/or exposure to 
environmental hazards. For example, populations lacking the resources 
and representation to combat the effects of climate change--which could 
include populations exposed to greater drought or flooding, or damaged 
crops, food, and water supplies--experience greater vulnerability to 
environmental hazards. Sensitive populations (e.g., infants and 
children, pregnant women, the elderly, and individuals with 
disabilities exacerbated by environmental hazards) may also be most 
affected by and vulnerable to the impacts of the plan or plan revision 
depending on the pollutants or other factors addressed by an EG.
    Communities in neighboring states or neighboring Tribal nations may 
also be impacted by a state plan and, if so, are pertinent 
stakeholders. In addition, to the extent a designated facility would 
qualify for a less stringent standard through consideration of RULOF as 
described in section III.E. of this preamble, the pertinent 
stakeholders would include the communities most affected by and 
vulnerable to the health and environmental impacts from the designated 
facility considered in a state plan for RULOF provisions.
    The EPA has determined that the definitions of meaningful 
engagement and pertinent stakeholders in subpart Ba provide the states 
sufficient specificity while allowing for flexibility in the 
implementation of meaningful engagement. Meaningful engagement is an 
enhancement of the existing public notice and comment requirements and 
is intended to promote the sharing of relevant information with, and 
the soliciting of input from, pertinent stakeholders at critical 
junctures during plan development. In particular, the

[[Page 80501]]

processes for meaningful engagement should allow for fair and balanced 
participation, including opportunities for communities most affected by 
and vulnerable to the impacts of a plan an opportunity to be informed 
of and weigh in on that plan. These procedural requirements, in turn, 
help ensure that a plan will adequately address the potential impacts 
to public health and welfare that are the core concern of CAA section 
111. Meaningful engagement can provide valuable information regarding 
health and welfare impacts experienced by the public (e.g., recurring 
respiratory illness, missed work or school days due to illness 
associated with pollution, and other impacts) and allow regulatory 
authorities to explore additional options to improve public health and 
welfare. Because the CAA section 111(d) program is designed to address 
widely varying types of air pollutants that may have very different 
types of impacts, from highly localized to regional or global, what 
constitutes fair and balanced participation among a broad set of 
pertinent stakeholders will be highly dependent on which stakeholders 
are directly impacted by a particular state plan.
    The EPA's authority for finalizing procedural requirements to 
strengthen the public participation provisions of the implementing 
regulations is provided by the authority of both CAA sections 111(d) 
and 301(a)(1). Under CAA section 111(d), one of the EPA's obligations 
is to ``establish a procedure similar to that provided by'' CAA section 
110, under which states submit plans that implement emission reductions 
consistent with the BSER. CAA section 110(a)(1) requires states to 
adopt and submit SIPs after ``reasonable notice and public hearings.'' 
\41\ The Act does not define what constitutes ``reasonable notice and 
public hearings'' under CAA section 110, and the EPA has reasonably 
interpreted this requirement in promulgating a process under which 
states submit state plans.\42\
---------------------------------------------------------------------------

    \41\ 42 U.S.C. 7410(a)(1).
    \42\ See 40 CFR 51.102; 40 CFR part 51, appendix V, section 2.1.
---------------------------------------------------------------------------

    Subpart Ba currently includes certain requirements for notice and 
public hearing in 40 CFR 60.23a(c) through (f). The notice requirements 
include prominent advertisement to the public of the date, time, and 
place of the public hearing, 30 days prior to the date of such hearing, 
and the advertisement requirement may be satisfied through publication 
to the internet. Id. at paragraph (d). A state may choose to cancel a 
public hearing if no request for one is received during the required 
notification period. Id. at paragraph (e).
    A fundamental purpose of the Act's notice and public hearing 
requirements is to ensure that all affected members of the public are 
able to participate in pollution control planning processes that impact 
their health and welfare.\43\ In order to effectuate this purpose of 
the Act's notice and public hearing requirements, the notice of the 
proposed plans and of the public hearings should be reasonably adequate 
in its ability to reach affected members of the public. While many 
states provide for notification of public engagement through the 
internet consistent with the current requirements under the CAA section 
111(d) implementing regulations, such notification may not be adequate 
to reach all those who are impacted by a CAA section 111(d) state plan 
and would benefit the most from participating in the state planning 
process. For example, data shows that as many as 30 million Americans 
do not have access to broadband infrastructure that delivers even 
minimally sufficient speeds, and that 25 percent of adults ages 65 and 
older report never going online.\44\ Accordingly, the EPA has 
determined that it is appropriate to improve the procedural public 
engagement requirements under CAA section 111(d) to ensure the 
statutory objectives are met.
---------------------------------------------------------------------------

    \43\ Consistent with this principle of providing reasonable 
notice under the CAA, under programs other than CAA section 111(d), 
current regulations governing other CAA programs similarly require 
states to provide specific notice to an area affected by a 
particular proposed action. See e.g., 40 CFR 51.161(b)(1) (requiring 
specific notice for an area affected by a state or local agency's 
analysis of the effect on air quality in the context of the New 
Source Review program (40 CFR 51.102(d)(2), (4), and (5) (requiring 
specific notice for an area affected by a CAA section 110 SIP 
submission).
    \44\ FACT SHEET: Biden-Harris Administration Mobilizes Resources 
to Connect Tribal Nations to Reliable, High-Speed Internet (December 
22, 2021). https://www.whitehouse.gov/briefing-room/statements-releases/2021/12/22/fact-sheet-biden-harris-administration-mobilizes-resources-to-connect-tribal-nations-to-reliable-high-speed-internet/; 7 percent of Americans don't use the internet. Who 
are they? Pew Research Center (April 2, 2021), https://www.pewresearch.org/fact-tank/2021/04/02/7-of-americans-dont-use-the-internet-who-are-they/.
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    Given the public health and welfare objectives of CAA section 
111(d) in regulating specific existing sources, it is reasonable to 
include a meaningful engagement component as part of the state plan 
development public participation process in order to further these 
objectives. Additionally, CAA section 301(a)(1) provides that the EPA 
is authorized to prescribe such regulations ``as are necessary to carry 
out [its] functions under [the CAA].'' As finalized, the meaningful 
engagement components of this rule would effectuate the EPA's function 
under CAA section 111(d) in prescribing a process under which states 
submit plans to implement the statutory directives of this section and 
promote the statutory objective that all pertinent stakeholders have 
reasonable notice of relevant information and the opportunity to 
participate in the state plan development throughout the process. 
Ongoing engagement between states and pertinent stakeholders will help 
ensure that plans achieve the appropriate level of emission reductions, 
that communities most affected by and vulnerable to the health and 
environmental impacts from the designated facilities share in the 
benefits of the state plan, and that these communities are protected 
from being adversely impacted by the plan.
    To promote meaningful engagement, the EPA is finalizing as part of 
the completeness criteria in 40 CFR 60.27a(g) procedural requirements 
for states to describe in their plan submittals how they engaged with 
pertinent stakeholders. As proposed, the state will be required to 
describe, in its plan submittal, (1) a list of the pertinent 
stakeholders identified by the state; (2) a summary of engagement 
conducted; and (3) a summary of the stakeholder input received. The EPA 
is also finalizing a fourth component as part of the procedural 
completeness demonstration--that the state also includes (4) a 
description of how stakeholder input was considered in the development 
of the plan or plan revisions. The EPA will review the state plan to 
ensure it includes these required descriptions regarding meaningful 
public engagement as part of its completeness evaluation of a state 
plan submittal. If a state plan submission does not include the 
required elements for notice and opportunity for public participation, 
including the procedural requirements at 40 CFR 60.23a(i) and 
60.27a(g)(2)(ix) for meaningful engagement, this may be grounds for the 
EPA to find the submission incomplete or (where a plan has become 
complete by operation of law) to disapprove the plan.
    While the EPA is finalizing procedural requirements for meaningful 
engagement as completeness criteria and is not prescribing how states 
proceed with such engagement, we understand states would find it useful 
to consider guidance as to how such engagement could be meaningfully 
conducted. In light of this interest, the following paragraphs provide 
examples and guidance which the EPA

[[Page 80502]]

encourages states to consider in designing their own meaningful 
engagement programs.
    In considering approaches for meaningful engagement, states should 
consider the identification of pertinent stakeholders; developing a 
strategy for engagement with the identified pertinent stakeholders; 
making information available in a transparent manner; and providing 
adequate and accessible notice. First, it would be reasonable for 
states to identify pertinent stakeholders considering information 
specific to the applicable EG, including the nature of the designated 
pollutants at issue and the communities likely to be impacted by 
facilities in the source category. The EPA intends to specifically 
provide information on impacts of designated pollutant emissions to 
assist states in the identification of their pertinent stakeholders, in 
addition to any other guidance that EPA may find it reasonable to 
provide in the applicable EG. Moreover, in developing a strategy for 
engagement, it would be reasonable for states to share information and 
solicit input on plan development and on any accompanying assessments. 
Finally, in providing transparent and adequate notice of plan 
development, states should consider that internet notice alone may not 
be adequate for all stakeholders, given lack of access to broadband 
infrastructure in many communities. Thus, in addition to internet 
notice, examples of prominent advertisement for engagement and public 
hearing may include notice through newspapers, libraries, schools, 
hospitals, travel centers, community centers, places of worship, gas 
stations, convenience stores, casinos, smoke shops, Tribal Assistance 
for Needy Families offices, Indian Health Services, clinics, and/or 
other community health and social services as appropriate for the 
emission guideline addressed.
    The EPA believes the following example, while not tailored to 
specific designated facilities but to a source category for recent EG 
development, provides states with ideas for how they can structure 
their own meaningful engagement activities.\45\ Prior to the November 
2021 proposal for the ``Standards of Performance for New, 
Reconstructed, and Modified Sources and Emissions Guidelines for 
Existing Sources: Oil and Natural Gas Sector Climate Review'' (86 FR 
63110), the EPA conducted meaningful engagement with pertinent 
stakeholders. For the pre-proposal stakeholder outreach, the EPA 
engaged with stakeholders through information posted on the internet, 
meetings, training webinars, and public listening sessions to 
disseminate information regarding this action, communicate how to 
submit comments on the proposed rule, and receive stakeholder input 
about the industry and its impact. In addition to the pre-proposal 
stakeholder engagement, the EPA conducted additional post-proposal 
training during the comment period on the proposed rule and held a 
public hearing. The EPA conducted three half-day post-proposal 
trainings to provide background information, an overview of the 
proposed rule, stakeholder panel discussions, and information on how to 
effectively engage in the regulatory process. The trainings were open 
to the public, focusing on individuals from and representatives of 
communities with EJ concerns, Tribes, and small businesses. Further 
considerations, analyses, and outreach relevant to meaningful 
engagement are presented in sections VI.\46\ and VII.\47\ of the 
preamble for that action and could help states in designing, planning, 
and developing their own outreach and engagement plans associated with 
the development and implementation of their state plans. An additional 
resource is the memorandum on stakeholder outreach \48\ for the ``New 
Source Performance Standards for Greenhouse Gas Emissions from New, 
Modified, and Reconstructed Fossil Fuel-Fired Electric Generating 
Units; Emission Guidelines for Greenhouse Gas Emissions from Existing 
Fossil Fuel-Fired Electric Generating Units; and Repeal of the 
Affordable Clean Energy Rule'' proposed rule (88 FR 33240, May 23, 
2023). This memorandum provides states with another example of the 
types of activities and processes that the EPA has found appropriate 
for meaningfully engaging with stakeholders in the particular context 
of EG development.
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    \45\ The EPA emphasizes that the appropriateness of any 
meaningful engagement strategy will depend on the specific context, 
including the sources and pollutants addressed by the EG, the scope 
and scale of the proposed regulation or plan, and the pertinent 
stakeholders. The activities and processes included in the examples 
of meaningful engagement in this preamble were tailored to the 
specific circumstances of EPA's EG development.
    \46\ See 86 FR 63110, 63140.
    \47\ See 86 FR 63110, 63145.
    \48\ See Docket ID No. EPA-HQ-OAR-2023-0072-0002.
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    The EPA recognizes that the state planning process is different 
than a national rulemaking and may benefit from different types of 
engagement. Nonetheless, the information and examples the EPA has 
provided on meaningful engagement can serve as an example of what types 
of engagement states should consider for their meaningful engagement 
processes. In addition, to further assist states in the meaningful 
engagement efforts, the EPA expects to develop resources to aid states 
in establishing meaningful engagement best practices, while recognizing 
that states have differing situations and that best practices will not 
be ``one size fits all.'' One resource that states may find helpful in 
developing their own best practices is the ``Public Involvement Policy 
of the US Environmental Protection Agency,'' \49\ which is currently 
under revision. Another helpful resource the EPA has developed is the 
``Capacity Building Through Effective Meaningful Engagement'' 
booklet.\50\ The booklet is also available in the docket for this rule. 
Additionally, most states have opted into the EPA Climate Pollution 
Reduction Grant Program (CPRG),\51\ developed under the Inflation 
Reduction Act.\52\ To assist states that are participating in the CPRG, 
the EPA is conducting training for states on meaningful engagement, 
sharing case studies, best practices, and lessons learned through 
ongoing EPA-led CPRG forums. The EPA expects that, with experience and 
shared access to information on best practices, approaches to address 
challenges and barriers, and other resources and collaborative 
opportunities, meaningful engagement practices at the state and Federal 
level will continue to improve.
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    \49\ https://archive.epa.gov/publicinvolvement/web/pdf/policy2003.pdf.
    \50\ https://www.epa.gov/system/files/documents/2023-09/epa-capacity-building-through-effective-meaningful-engagement-booklet_0.pdf.
    \51\ See U.S. EPA Office of Air and Radiation ``Climate 
Pollution Reduction Grants Program: Formula Grants for Planning 
Program Guidance for States, Municipalities, and Air Pollution 
Control Agencies'' (March 1, 2023), https://www.epa.gov/system/files/documents/2023-02/EPA%20CPRG%20Planning%20Grants%20Program%20Guidance%20for%20States-Municipalities-Air%20Agencies%2003-01-2023.pdf (overview of the 
CPRG). See also U.S. EPA, ``Status of Notice of Intent to 
Participate (NOIP) Submittals by States (March 31, 2023), https://www.epa.gov/system/files/documents/2023-04/NOIP%20Status%20Lists.pdf 
(list of states who have opted in to the CPRG as of March 31, 2023).
    \52\ Inflation Reduction Act section 60114.
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D. Regulatory Mechanisms for State Plan Implementation

    CAA section 111(d)(1) requires the EPA to promulgate regulations 
that establish a procedure ``similar'' to that provided by CAA section 
110 for each state to ``submit to [the EPA] a state plan which . . . 
establishes standards of performance . . . and . . . provides for the 
implementation and enforcement of such standards.'' The EPA reasonably 
interprets this provision, particularly

[[Page 80503]]

the ``similar'' clause, as referring to all the procedural provisions 
provided in CAA section 110 which serve the same purposes of providing 
useful flexibilities for states and EPA actions that help ensure 
emission reductions are appropriately and timely implemented.
    The EPA proposed to incorporate 5 regulatory mechanisms as 
amendments to the implementing regulations under 40 CFR part 60, 
subpart Ba, governing the processes under which states submit plans and 
the EPA acts on those plans. 87 FR 79176, 79193-96 (Dec. 23, 2022). The 
proposed additional regulatory mechanisms include: (1) partial approval 
and disapproval of state plans by the EPA; (2) conditional approval of 
state plans by the EPA; (3) parallel processing of plans by the EPA and 
states; (4) a mechanism that allows the EPA to call for revision of a 
previously approved state plan; and (5) an error correction mechanism 
for the EPA to revise its prior action on a state plan.\53\ These 
mechanisms were proposed to update the implementing regulations to 
better align with the flexible procedural tools that Congress added 
into section 110 of the CAA in the 1990 Amendments. The EPA is 
finalizing the adoption and incorporation of these mechanisms into 
subpart Ba as the EPA has interpreted and applied them in the context 
of CAA section 110.
---------------------------------------------------------------------------

    \53\ These regulatory mechanisms were also previously proposed 
to be added to subpart B in 2015 and largely received support from 
states, the public, and stakeholders, but were never finalized. 80 
FR 64965 (October 23, 2015).
---------------------------------------------------------------------------

    As explained in the notice of proposed rulemaking, the 
interpretation that CAA section 111(d)(1) authorizes the EPA to adopt 
procedures ``similar'' to those under CAA section 110 for the entire 
state plan process, and not just the initial plan submission process, 
is strengthened by the provisions in CAA section 111(d)(2), which 
provide that the EPA has the ``same'' authority to promulgate a Federal 
plan for a state that has failed to submit a satisfactory plan as under 
CAA section 110(c), and to enforce state plan requirements as it does 
for SIPs under CAA sections 113 and 114. This is because, read 
together, CAA section 111(d)(1) and (2) call for the set of essential 
procedural requirements for state and Federal plan development and 
implementation and enforcement that generally reflect the essential 
procedural requirements for SIPs and FIPs in section 110.\54\ In that 
context, it is reasonable to read CAA section 111(d)(1) as authorizing 
the EPA to promulgate procedures for section 111(d) that are comparable 
to CAA section 110 procedures for the overall state plan process. 
Moreover, the EPA believes that it is reasonable, in promulgating the 
regulations required under CAA section 111(d)(1), to look to the 
mechanisms and flexibilities that Congress has deemed appropriate for 
states and the EPA to use in the highly analogous context of state and 
Federal implementation plans.
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    \54\ Compare CAA section 111(d)(1) (requiring states to submit 
state plans that include specified types of measures that, in turn, 
meet minimum EPA requirements) and section 111(d)(2) (indicating 
that the EPA must review and approve or disapprove state plans, 
requiring the EPA to promulgate a Federal plan if the state does not 
submit a satisfactory plan, authorizing the EPA to enforce state 
plan measures) with section 110(a)(1)-(2) (requiring states to 
submit SIPs that include specified types of measures that in turn 
meet minimum EPA requirements), section 110(k) (requiring the EPA to 
review and approve or disapprove SIPs), section 110(c) (requiring 
the EPA to promulgate a FIP if the state does not submit a plan or 
the EPA disapproves the state plan) and 113(a)(1) (authorizing the 
EPA to enforce SIP measures).
---------------------------------------------------------------------------

    The availability of these 5 regulatory mechanisms will streamline 
the state plan review and approval process, accommodate variable state 
processes, facilitate cooperative federalism, further protect public 
health and welfare, and generally enhance the implementation of the CAA 
section 111(d) program. Together, these mechanisms provide greater 
flexibility, may reduce processing time, and have proven to be very 
useful tools for the review and processing of CAA section 110 SIPs.
    Overall, the comments received for incorporating the 5 regulatory 
mechanisms were favorable, in particular noting that the mechanisms 
would offer not only procedural improvements long sought by state 
agencies but also reflect the flexibility offered in section 111 of the 
CAA, consistent with the Act's cooperative approach, and would expand 
state planning options while conserving state resources. However, one 
commenter noted generally that for 111(d) plans, the CAA directs the 
EPA to establish a procedure similar to CAA section 110 for SIP 
submittals but does not require those procedures to be identical. This 
commenter contended that while the CAA specifically authorized various 
flexible mechanisms in sections 110(k)(2)-(6), the plain language of 
CAA section 111 does not provide for these options for 111(d) plans.
    The EPA agrees that procedures adopted under CAA section 111(d)(1) 
need not be identical to CAA section 110 procedures, but interprets 
section 111(d)(1) to authorize the EPA to adopt procedures under 
111(d)(1) which are substantially the same as those outlined under 
section 110, including section 110 procedural mechanisms.\55\ 
Additionally, as explained above, while CAA section 111(d)(1) directs 
EPA to establish ``a procedure . . . under which each State shall 
submit to the Administrator a plan,'' section 111(d)(2) further 
provides that EPA also has authority to prescribe a Federal plan where 
states fail to submit a satisfactory plan and to enforce the provisions 
of state plans in cases where states fail to do so. Congress saw fit to 
provide mechanisms such as conditional approval and SIP calls under CAA 
section 110 for the purpose of EPA evaluation and action on, and 
enforcement of, SIPs, and the Agency believes it is reasonable to look 
to section 110 as evidence of the types of mechanisms that are 
reasonable for EPA to provide for the same purposes under section 
111(d).
---------------------------------------------------------------------------

    \55\ See Merriam Webster's Dictionary, defining ``Similar'' as 
``having characteristics in common'' or ``alike in substance and 
essentials.'' https://www.merriam-webster.com/dictionary/similar.
---------------------------------------------------------------------------

    These regulatory mechanisms will provide flexibility and support 
efficiency to the states and the EPA in the submission and processing 
of state plans. For the reasons discussed in the following sections, 
the EPA is finalizing these provisions.
1. Partial Approval and Disapproval
    The EPA proposed a provision similar to that under CAA section 
110(k)(3) for the EPA to partially approve and partially disapprove 
severable portions of a state plan submitted under CAA section 111(d). 
Under CAA section 110(k)(3), ``[i]f a portion of the plan revision 
meets all the applicable requirements of this chapter, the 
Administrator may approve the plan revision in part and disapprove the 
plan revision in part. The plan revision shall not be treated as 
meeting the requirements of this chapter until the Administrator 
approves the entire plan revision as complying with the applicable 
requirements of this chapter.'' Subpart Ba currently authorizes the EPA 
to ``approve or disapprove [the state] plan or revision or each portion 
thereof'' (40 CFR 60.27a(b)) but does not explicitly specify whether 
such actions may be partial.
    One commenter stated that the partial approval and disapproval 
mechanisms the EPA proposed appear to be aimed at providing a way for 
the EPA to approve model rule provisions and disapprove RULOF 
provisions. The EPA disagrees with this comment. The EPA reviews each 
provision of a state plan, regardless of the type of provision, to 
determine whether it meets the applicable

[[Page 80504]]

statutory and regulatory requirements. If it meets the applicable 
requirements, the EPA must approve it. It is entirely possible, and in 
fact common, for some state plan provisions to comport with the 
applicable requirements and others not to. Pursuant to this mechanism, 
the EPA may partially approve or partially disapprove a state plan when 
portions of the plan are approvable, but other discrete and severable 
portions are not. In such cases, the purposes of a CAA section 111(d) 
EG, as well as section 111(d)'s framework of cooperative federalism, 
would be better served by allowing the state to move forward with 
implementing those portions of the plan that are approvable, rather 
than to disapproving the full plan and potentially delaying 
implementation of beneficial emission reductions. This mechanism is 
consistent with the ALA decision's emphasis on ensuring timely 
mitigation of harms to public health and welfare, as problematic parts 
of a state plan submission would not stall the implementation of 
emission reductions at designated facilities for which a portion of a 
plan could be approved, thus efficiently reducing the time from EG 
promulgation to implementation of emission reductions at those 
facilities.
    The EPA is finalizing this provision so that it is similar to CAA 
section 110(k)(3), providing clarity on the EPA's authority to 
partially approve plans and the circumstances under which it may be 
used. As explained at proposal, the portion of a state plan that the 
EPA may partially approve must be ``severable.'' A portion is severable 
when: (1) the approvable portion of the plan does not depend on or 
affect the portion of the plan that cannot be approved, and (2) 
approving a portion of the plan without approving the remainder does 
not alter the approved portion of a state plan in any way that renders 
it more stringent than the state's intent. See Bethlehem Steel v. 
Gorsuch, 742 F.2d 1028, 1034 (7th Cir. 1984). The EPA's decision to 
partially approve and partially disapprove a plan must go through 
notice and comment rulemaking. As a result, the public will have an 
opportunity to submit comment on the appropriateness and legal 
application of this mechanism on a particular state plan submission. A 
partial disapproval of a plan submission would have the same legal 
effect as a full disapproval for purposes of the EPA's authority under 
CAA section 111(d)(2)(A) to promulgate, for the partially disapproved 
portion of the plan, a Federal plan for the state to fill the gap. See 
section III.A.4 of this preamble for finalized timelines for 
promulgation of a Federal plan. If the EPA does promulgate a Federal 
plan for a partially disapproved portion, the state may, at any time, 
submit a revised plan to replace that portion. If the state does so, 
and the EPA approves the revised plan, then the EPA would withdraw the 
Federal plan for that state.
    This partial approval/disapproval mechanism also enables states to 
submit, and authorizes the EPA to approve or disapprove, state plans 
that are partial in nature and to address only certain elements of a 
broader program. For example, with this mechanism, states will be able 
to submit partial plans intended to replace discrete portions of a 
Federal plan, where appropriate. Partial submittals must meet all 
completeness criteria.
2. Conditional Approval
    The EPA proposed a mechanism analogous to the authority under CAA 
section 110(k)(4) to grant the EPA the ability to conditionally approve 
a state plan under CAA section 111(d). Under CAA section 110(k)(4), 
``[t]he Administrator may approve a plan revision based on a commitment 
of the state to adopt specific enforceable measures by a date certain, 
but not later than 1 year after the date of approval of the plan 
revision. Any such conditional approval shall be treated as a 
disapproval if the state fails to comply with such commitment.'' The 
proposed provision would authorize the EPA to conditionally approve a 
plan submission that substantially meets the requirements of an EG but 
that requires some additional, specified revisions to be fully 
approvable. For the EPA to conditionally approve a submission, the 
state Governor or their designee must commit to adopt and submit 
specific enforceable provisions to remedy the stipulated plan 
deficiency. The provisions required to be submitted by the state 
pursuant to a conditional approval would be treated as an obligation to 
submit a plan revision and be subject to the same processes and 
timeframes for the EPA action as other plan revisions (e.g., 
completeness determination, approval and/or disapproval).
    Comments were generally supportive of including the mechanism in 
subpart Ba for use by the EPA in acting on CAA 111(d) state plans. One 
commenter submitted that the EPA should limit conditional approvals to 
plans either with only procedural deficiencies or with substantive 
deficiencies that (1) apply to few designated facilities (e.g., no more 
than 5); (2) do not lead to impacts on vulnerable communities; and (3) 
are likely to be remedied by the state within one year. Comments were 
received both supporting and opposing the proposed 12-month time period 
for adopting and submitting the necessary revisions associated with a 
conditional approval. In particular, one commenter recommended allowing 
more than 12 months for submission of subsequent revisions that are 
required as part of conditional approvals that relate to RULOF 
provisions. After considering the comments received, the EPA is 
declining to explicitly limit the circumstances in which conditional 
approval may be used and is finalizing the 12-month period for 
submission of a plan revision pursuant to a conditional approval as 
proposed. First, the EPA views the conditional approval mechanism as a 
beneficial flexibility for states in instances in which partial 
disapproval may be appropriate because a discrete portion of a state 
plan does not meet the applicable requirements, but that deficiency is 
not so significant that it affects the substantial adequacy of the 
plan. CAA section 110(k)(4) supports this view, as Congress provided 
only 12 months for states correct the deficiency; 12 months is likely 
not sufficient for states to remedy significant substantive 
deficiencies in a plan. Thus, the EPA believes both that structure of 
the conditional approval mechanism already appropriately circumscribes 
its use and that extending the timeline for states to submit plan 
revisions pursuant to conditional approval would abrogate its utility 
as a way to address minor issues in a plan and encroach on 
circumstances in which partial disapproval is more appropriate. Second, 
under the provisions being finalized in this rulemaking, in the event 
that EPA did partially disapprove a state plan in lieu of conditionally 
approving it, the Agency would have 12 months to promulgate a Federal 
plan to fill the gap. See 40 CFR 60.27a(c)(2). It would be 
inappropriate to provide states a longer period of time in the same 
circumstances to remedy a deficiency.
    As finalized, if the state fails to meet its commitment to submit 
the measures within 12 months, the conditional approval automatically 
converts to a disapproval. If a conditionally approved state plan 
converts to a disapproval due to either the failure of the state to 
timely submit the required measures or if the EPA finds the submitted 
measures to be unsatisfactory, such disapproval would be grounds for 
implementation of a Federal plan under CAA section 111(d)(2)(A). The 
EPA will publish a notice in the Federal Register and, if appropriate, 
on the public website

[[Page 80505]]

established for the EG notifying the public that the conditional 
approval is converted to a disapproval. As described in section 
III.A.4. of this preamble, the EPA would be required to promulgate a 
Federal plan within 12 months of state's failure to submit the required 
measures or the EPA's disapproval of measures submitted to address the 
conditional approval.
    Commenters asserted that the EPA should take action to develop a 
Federal plan immediately upon issuing a conditional approval, and 
further asserted that the EPA should not allow the conditional approval 
mechanism to toll the Federal plan clock and thereby delay needed 
public health and welfare protections. A conditional approval is not a 
disapproval and therefore there has been no failure on the part of the 
state and thus will not trigger a corresponding Federal plan for the 
given state nor initiate a timeline for the EPA to provide a Federal 
plan. Conditional approvals will be evaluated and designed on a case-
by-case basis, with consideration of public health and welfare, and are 
expected to result in approved state plans and therefore not require 
the development of a Federal plan. The commenters also noted the EPA 
proposed to allow 12 months in which to impose a Federal plan following 
disapproval of a previously conditionally approved plan and stated 
instead the EPA should start the clock for developing a Federal plan as 
soon as a state plan submission is conditionally approved if the EPA 
has determined that there is a significant possibility that the 
deficiencies will not be corrected. The EPA disagrees with this comment 
because the Agency would not conditionally approve a plan if the 
deficiencies were not expected to be corrected; in this instance, a 
partial disapproval of the plan would be appropriate.
    Another commenter requested that the EPA clarify the applicable 
compliance deadline for a state plan that is conditionally approved by 
the Agency. The commenter contended that the proposed rule did not 
specify the ``trigger'' date for compliance deadlines when the EPA 
conditionally approves a state plan, and recommended that, in this 
scenario, compliance deadlines should begin to run when the state 
satisfies the condition(s) established by the EPA. However, the EPA 
notes that compliance timeframes for designated facilities are 
specified in the applicable EGs. To the extent that the Administrator 
conditionally approves a plan, the compliance timeframes must still 
meet the requirements in the EG. A conditional approval may not be an 
appropriate action if the result would be a significant delay in 
compliance, as that is inconsistent with the intention of adding this 
flexibility for state plan processing.
    Incorporating this mechanism under the subpart Ba will have the 
benefit of allowing a state with a substantially complete and 
approvable program to begin implementing it, while also promptly making 
specific changes that ensure it fully meets the requirements of CAA 
section 111(d) and of the applicable EGs. The EPA is therefore 
finalizing this provision as proposed at 40 CFR 60.27a(b)(2).
3. Parallel Processing
    The EPA proposed to include a mechanism similar to that for SIPs 
under 40 CFR part 51 appendix V, section 2.3.1., for parallel 
processing a plan that does not yet meet all of the administrative 
completeness criteria under 40 CFR 60.27a(g)(2). This streamlined 
process allows the EPA to propose approval of such a plan in parallel 
with the state completing its process to fully adopt the plan in 
accordance with the required administrative completeness criteria, and 
then allows the EPA to finalize approval once those criteria have been 
fully satisfied and a final plan has been submitted.
    At proposal, the EPA explained that parallel processing under 
subpart Ba would be subject to certain conditions. In lieu of the 
letter required under 40 CFR 60.27a(g)(2)(i), the state must submit the 
proposed plan with a letter requesting the EPA propose approval through 
parallel processing. Under the parallel processing procedures, a state 
will be temporarily exempt from the administrative completeness 
criteria as defined by 40 CFR 60.27a(g)(2) regarding legal adoption of 
the plan (40 CFR 60.27a(g)(2)(ii) and (v)) and from some of the public 
participation criteria (40 CFR 60.27a(g)(2)(vi), (vii), and (viii)). 
However, as with parallel processing for SIPs under 40 CFR part 51, 
appendix V, in lieu of these administrative criteria, the state must 
include a schedule for final adoption or issuance of the plan and a 
copy of the proposed/draft regulation or the document indicating the 
proposed changes to be made, where applicable. Note that a proposed 
plan submitted for parallel processing must still meet all the criteria 
for technical completeness as defined by 40 CFR 60.27a(g)(3) and meet 
all other administrative completeness criteria as defined by 40 CFR 
60.27a(g)(2). If these conditions are met, the submitted plan may be 
considered for purposes of the EPA's initial plan evaluation and 
proposed rulemaking action.
    The exceptions to the administrative criteria described above only 
apply to the EPA proposing action on the state plan. If the EPA has 
proposed approval through parallel processing, the state must still 
submit a fully adopted and final plan that meets all of the 
completeness criteria under 40 CFR 60.27a(g), including the 
requirements for legal adoption and public engagement, before the EPA 
can finalize its approval. If the state finalizes and submits to the 
EPA a plan that includes changes relative the plan that the EPA 
proposed to approve, the EPA will evaluate those changes for 
significance. If any such changes are found by the EPA to be 
significant (e.g., changes to the stringency or applicability of a 
particular standard of performance), then the state submittal would be 
treated as an initial submission and the EPA would be required to re-
propose its action on the final plan and to provide an opportunity for 
public comment.
    Note further that once the state plan submission deadline passes, 
the EPA retains the authority to initiate development of a Federal plan 
at any time for a state that has not submitted a complete plan, even if 
a state has requested parallel processing and the EPA has proposed an 
action. The EPA intends to continue working collaboratively with states 
who are in the process of adopting and submitting state plans but notes 
that states must remain mindful of regulatory deadlines for CAA section 
111(d) plan submissions even when seeking to use the parallel 
processing mechanism.
    While comments were generally supportive of the EPA adopting 
parallel processing for CAA section 111(d) plans, some commenters 
expressed concern that the purpose and benefits of meaningful 
engagement would not be realized in the state plan development process 
if this mechanism were finalized as proposed. One commenter noted that 
the proposed parallel processing provision appeared to indicate that 
the state can submit its plan to the EPA prior to conducting meaningful 
engagement, and that the EPA is expecting an informational meeting 
rather than actual engagement from the public during the meaningful 
engagement process. Another commenter remarked that if a state does not 
include meaningful engagement before submitting its initial plan to the 
EPA, the proposed parallel processing mechanism creates an inherent 
disincentive for the state to modify a plan under this mechanism in 
response to any public engagement which occurs

[[Page 80506]]

subsequent to submittal, and further stated this would increase the 
disparity between the feedback received from the individuals the EPA 
designed the meaningful engagement provisions to protect and feedback 
from individuals or organizations with plentiful resources for 
proactive engagement. The commenters also asserted that members of the 
public, knowing that a version of the plan is already under Federal 
review, would be more likely to doubt that their feedback would have an 
impact on the final product.
    The EPA agrees with these commenters that, as proposed, exempting 
meaningful engagement from completeness criteria requirements under 
parallel processing would be a disincentive to meeting to the goals of 
meaningful engagement. In fact, as defined in this action, meaningful 
engagement is the ``timely engagement with pertinent stakeholders and/
or their representatives in the plan development or plan revision . . 
.'' (emphasis added). Thus, meaningful engagement should occur well in 
advance of a state being ready to submit a plan to the EPA for parallel 
processing. The EPA is therefore excluding the meaningful engagement 
completeness criteria defined at 40 CFR 60.27a(g)(2)(ix) from the 
completeness criteria exceptions provided under the finalized parallel 
processing provision at Sec.  60.27a(h)(4). That is, states must 
include the information required under Sec.  60.27a(g)(2)(ix) in any 
proposed state plans submitted to the EPA for parallel processing. 
Meaningful engagement is integral in early state plan development and 
should be included as part of the completeness criteria for parallel 
processing.
    The EPA is finalizing as part of the completeness criteria in 40 
CFR 60.27a(g) procedural requirements for states to describe in their 
plan submittals how they engaged with pertinent stakeholders. The state 
will be required to describe, in its plan submittal, (1) a list of 
pertinent stakeholders identified by the state; (2) a summary of 
engagement conducted; (3) a summary of the stakeholder input received; 
and (4) a description of how stakeholder input was considered in the 
development of the plan or plan revisions.
4. State Plan Call
    Under CAA section 110(k)(5), the EPA may call for a revision of a 
state implementation plan ``[w]henever the Administrator finds that the 
applicable implementation plan . . . is substantially inadequate to . . 
. comply with any requirement of [the Act].'' The EPA proposed to add a 
mechanism analogous to this ``SIP call'' provision to subpart Ba at 40 
CFR 60.27a(i) under CAA section 111(d), which would authorize the EPA 
to find that a previously approved state plan does not meet the 
applicable requirements of the CAA or of the relevant EG and to call 
for a plan revision. This mechanism is a useful tool for ensuring that 
approved state plans continue to meet the requirements of the EGs and 
of the CAA over time. This may be particularly important because EGs 
that achieve emission reductions from specific source categories may be 
implemented over many years.
    As proposed, the state plan call provision stated that, whenever 
the Administrator finds that the applicable plan is substantially 
inadequate to meet the requirements of the applicable EG, to provide 
for the implementation of such plan or to otherwise comply with any 
applicable requirement of subpart Ba or the CAA, the Administrator 
shall require the state to revise the plan as necessary to correct such 
inadequacies. The EPA explained that a plan call would be generally 
appropriate under two circumstances: when legal or technical conditions 
arise after the EPA approves a state plan that undermine the basis for 
the approval and when a state fails to adequately implement an approved 
state plan. In the first circumstance, a change in conditions or 
circumstances could render an approved plan inconsistent with the EG, 
subpart Ba, and/or the CAA, necessitating a plan revision to realign it 
with the applicable requirements. For example, a court decision 
subsequent to the approval of a plan may render that plan substantially 
inadequate to meet applicable CAA requirements resulting from the 
change in law.\56\ Or, the EPA may determine that technical conditions, 
such as design assumptions, about control measures that were the basis 
for a state plan approval later prove to be inaccurate, meaning that 
the plan would be substantially inadequate to achieve the emission 
reductions required by the EG and therefore the plan should be 
revised.\57\
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    \56\ An example of this circumstance in the context of CAA 
section 110 is the 2015 ``SSM SIP Call'', which required states to 
correct previously approved SIP provisions based on subsequent court 
decisions regarding startup, shutdown, and malfunctions (SSM) 
operations. 80 FR 33840, June 12, 2015.
    \57\ For example, the 1998 ``NOX SIP call'' required 
states to submit SIP revisions addressing NOX emissions 
found, after SIP approvals, to significantly impact the attainment 
of air quality standards in other states due to atmospheric 
transport. 63 FR 57356, October 27, 1998.
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    The second circumstance in which a state plan call may be 
appropriate is when a state fails to adequately implement an approved 
state plan. In this case, the approved state plan may facially meet all 
applicable requirements, but a failure in implementation (e.g., due to 
changes in available funding, resources, or legal authority at the 
state level) renders the plan substantially inadequate to meet the 
requirements of the EG and CAA section 111(d). In this circumstance, a 
state, in response to a plan call, would either be required to submit a 
plan revision that provides for implementation of the plan's 
requirements given the state's actual circumstances or to provide 
demonstration that the plan is being adequately implemented as 
approved.
    Consistent with the SIP call process under CAA section 110(k)(5), 
the EPA proposed that, after it finds that a state's approved plan is 
substantially inadequate to comply with applicable requirements, it 
would require the state to revise the plan as necessary to correct 
inadequacies. The EPA proposed that such finding and notice must be 
public. The plan call notice would identify the plan inadequacies 
leading to the plan call and establish a reasonable deadline (not to 
exceed 12 months after the date for such notice) for submission of a 
plan revision and/or demonstration of appropriate implementation of the 
approved plan.
    A number of commenters asserted that the EPA is not authorized to 
issue a call for state plans under CAA section 111(d) because Congress 
did not provide this explicit authority in CAA section 111. Some 
commenters also expressed concern that this mechanism undermines the 
regulatory certainty approved plans provide to facilities. 
Additionally, some commenters contended that CAA sections 113 and 114 
address the condition of states not properly implementing approved 
state plans such that a state plan call mechanism is unnecessary.
    As explained at the start of this section of the preamble (section 
III.D.), the EPA interprets CAA section 111(d)(1)'s direction to 
prescribe regulations establishing a procedure similar to that provided 
by CAA section 110 for the submission of state plans to authorize the 
EPA to adopt the section 110 procedural mechanisms. Additionally, CAA 
section 111(d)(2) provides that EPA shall have the same authority as 
under CAA section 110(c) to prescribe a Federal plan where a state 
fails to submit a satisfactory plan, as well as the same authority as 
under CAA sections 113 and 114 to enforce the

[[Page 80507]]

provisions of a state plan where the state fails to enforce them. 
Congress did not specify how the EPA is to exercise its authority to 
approve or disapprove state plans, promulgate Federal plans, and 
oversee and enforce state plan implementation on an ongoing basis, and 
the EPA finds it reasonable to look to other mechanisms under the CAA 
that Congress has provided for substantially the same purpose. That is, 
the EPA believes CAA sections 111(d)(1) and 111(d)(2), taken together, 
provide the legal basis for incorporating mechanisms into subpart Ba 
that ensure the ongoing compliance of state plans with the applicable 
requirements, including the state plan call mechanism of CAA section 
111(k)(5).
    While CAA sections 113 and 114 provide the EPA authority to enforce 
the provisions of state plans through, inter alia, issuance of 
administrative orders and penalties, civil actions in the case of 
violations, and use of monitoring, reporting, recordkeeping, and 
compliance certifications, the EPA believes it is also reasonable and 
helpful to provide a mechanism for states to bring their state plans 
into compliance with the applicable requirements. A state's failure to 
implement its approved plan may result if that plan's implementation or 
enforcement measures, e.g., monitoring, reporting, and verification 
requirements, prove inadequate to enable a state to ensure that a 
designated facility is meeting its standards of performance. A failure 
to implement may also arise, as described above, where an approved 
state plan contains the appropriate implementation and enforcement 
measures but changes in, e.g., available funding, resources, or legal 
authority at the state level render the plan, as it is being 
implemented, substantially inadequate to meet the requirements of 
subpart Ba, the EG, or CAA section 111(d). In either instance, a 
reasonable alternative to EPA enforcement may be for the Agency to 
issue a state plan call in order to give the state an opportunity to 
remedy the deficiency or to provide demonstration that the plan is 
being or will be adequately implemented as approved. As with all of the 
regulatory mechanisms being incorporated into subpart Ba in this 
rulemaking, the EPA interprets CAA sections 111(d)(1) and (2) as 
collectively providing the authority to provide for procedures for 
ensuring that state plans remain ``satisfactory'' over the long time 
periods over which they are implemented, given that subsequent findings 
or conditions may affect the basis for a previous plan approval.
    The EPA acknowledges that a call for revision of a state plan may 
result in a change in the requirements to which regulated entities are 
subject under than plan. However, as explained above, state plan calls 
are appropriate in two general circumstances: when legal or technical 
conditions arise that abrogate the basis of the initial state plan 
approval and when a state fails to adequately implement an approved 
state plan. In either of these two instances, the plan as it is 
currently being implemented fails to meet the applicable requirements. 
The EPA believes it would be neither consistent with the statute nor 
reasonable to fail to correct a state plan under these circumstances 
and that the state plan call mechanism, which provides for notice to 
the state and the public and a process for revising the state plan that 
is intended to cause as little disruption to the original plan as 
possible, is appropriate. The state plan call provisions state that 
``[a]ny finding under this paragraph shall, to the extent the 
Administrator deems appropriate, subject the State to the requirements 
of this part to which the State was subject when it developed and 
submitted the plan for which such finding was made, except that the 
Administrator may adjust any dates applicable under such requirements 
as appropriate.'' \58\
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    \58\ The regulations being finalized at Sec.  60.27a(i)(1) 
further provided that if the Administrator makes the finding in 
Sec.  60.27a(i) on the basis that a State is failing to implement an 
approved plan, or part of an approved plan, the State may submit a 
demonstration to the Administrator it is adequately implementing the 
requirements of the approved state plan in lieu of a plan revision. 
Such demonstration must be submitted by the deadline established 
under Sec.  60.27a(i).
---------------------------------------------------------------------------

    Several commenters noted that the proposed ``not to exceed 12 
months'' timeline associated with the state call revision provision may 
be inadequate for states to respond to a state plan call and noted that 
this time is shorter than that provided for plan development. However, 
because a state plan call would represent that a plan is substantially 
inadequate to meet an EG after implementation of the plan was supposed 
to be underway, and compliance deadlines may have already passed, a 
more expeditions timeline to fix the problem than the deadline for 
initial plan development is imperative to the public health concerns. 
Additionally, the EPA anticipates that in many instances a state plan 
call would impact a discrete portion or element of a plan that will not 
require the same amount of time the EPA is allotting for initial state 
plan development and submission, i.e., 18 months, to correct. The EPA 
believes 12 months is a reasonable timeframe and allows for public 
outreach and state processes while ensuring the deficiency is 
expeditiously corrected to address any outstanding public health and 
welfare concerns associated with a deficient plan, consistent with the 
ALA decision. However, the Agency also acknowledges that this may not 
be true in every instance. The EPA is therefore finalizing the state 
plan call mechanism with a change relative to proposal to provide that 
plan revisions associated to a state plan call shall be submitted to 
the Administrator within 12 months or within a period as determined by 
the Administrator, instead of ``not to exceed 12 months.'' Because the 
CAA contains numerous deadlines requiring states to submit various 
state implementation plans within 12 months of a triggering event,\59\ 
the EPA believes it is reasonable to expect states to be able to submit 
state plan revisions pursuant to a state plan call within this 
timeframe as well. The final language provides more flexibility and 
allows that the EPA may supersede this 12-month timeframe in 
appropriate circumstances.
---------------------------------------------------------------------------

    \59\ See, e.g., CAA sections 110(k)(4), 129(b)(2), and 179(d).
---------------------------------------------------------------------------

    While this period is less than the time allotted for the submission 
of a full state plan (finalized in section III.A.1. of this preamble 
above as 18 months), it can provide a reasonable timeframe for public 
outreach and state processes while ensuring the deficiency is 
expeditiously corrected to address any outstanding public health and 
welfare concerns associated with a deficient plan, consistent with the 
ALA decision.
    With the exception of this revision to the timeline for states to 
submit revised state plans, the EPA is finalizing the state plan call 
mechanism at 40 CFR 60.27a(i) as proposed. As explained at proposal, 
any failure of a state to submit necessary revisions by the date set in 
the call for state plan revisions constitutes a failure to submit a 
required plan submission. Therefore, pursuant to CAA section 
111(d)(2)(A), the EPA would have the authority to promulgate a Federal 
plan for the state within 12 months after the necessary revisions are 
due. If the state fails to submit a plan revision, to make an adequate 
demonstration within the prescribed time pursuant to 40 CFR 
60.27a(i)(1), or if the EPA disapproves a submission, then the EPA 
would be required to promulgate a Federal plan addressing the 
deficiency for sources within that state.

[[Page 80508]]

5. Error Correction
    Under CAA section 110(k)(6), the EPA may, on its own accord, revise 
its prior action on a state implementation plan under certain 
circumstances: ``[w]henever the Administrator determines that the 
Administrator's action approving, disapproving, or promulgating any 
plan or plan revision (or part thereof) . . . was in error, the 
Administrator may in the same manner as the approval, disapproval, or 
promulgation revise such action as appropriate without requiring any 
further submission from the State.'' The EPA proposed to add a 
mechanism analogous to this ``error correction'' provision to subpart 
Ba at 40 CFR 60.27a(j) under CAA section 111(d) and is finalizing that 
mechanism as proposed.
    As explained in the notice of proposed rulemaking, this error 
correction provision would authorize the EPA to revise its prior action 
when the EPA determines its own action on the state plan was in error. 
Specifically, this provision allows the EPA to revise its prior action 
in the same manner as used for the original action (e.g., through 
rulemaking) without requiring any further submissions from the state. 
In this manner, the error correction mechanism does away with 
unnecessary burdens on states based solely on an error made by the EPA, 
such as submitting a plan revision and the public participation related 
requirements under 40 CFR 60.23a (e.g., providing notice and holding a 
public hearing).
    CAA section 110(k)(6) is phrased broadly, and its legislative 
history makes clear that it ``explicitly authorizes EPA on its own 
motion to make a determination to correct any errors it may make in 
taking any action, such as . . . approving or disapproving any plan.'' 
See House Report No. 101-490 at 220. The circumstances that may give 
rise to an error that the EPA may correct with this mechanism depend on 
the specific facts and plan at issue, and the use of the mechanism is 
justified on a case-by-case basis. The EPA has previously used CAA 
section 110(k)(6) for correction of technical or clerical errors,\60\ 
for removal of substantive provisions from an EPA-approved state plan 
that did not relate to implementation, enforcement, or maintenance of 
the NAAQS or is otherwise permissible under the CAA for inclusion in 
the plan,\61\ and when the EPA in error approved a SIP that did not 
meet applicable requirements.\62\ These examples are not the only 
circumstances when the EPA has used CAA section 110(k)(6) in the past 
and do not limit the EPA for circumstances of error correction under 
section 111(d) in the future.
---------------------------------------------------------------------------

    \60\ For example, see 74 FR 57051, November 3, 2009, for 
correction of clerical and typographical errors in a portion of an 
Arizona SIP.
    \61\ For example, see 86 FR 24505 (May 7, 2021) (removal of 
asbestos requirements from a Kentucky SIP).
    \62\ For example, see 86 FR 23054, April 30, 2021, for error 
correction with respect to Kentucky's ``good neighbor obligations'' 
and SIP disapproval.
---------------------------------------------------------------------------

    One commenter, while not objecting to the inclusion of this 
mechanism, suggested the EPA should make clear in the regulations that 
this provision cannot be used to effect a change in policy because of a 
change in perspective on implementation that may arise from an 
administration transition, citing the need for designated facilities to 
have regulatory certainty and to avoid unexpected changes in regulatory 
requirements. Other commenters also noted that the proposed regulatory 
text does not place any limitations on the EPA's ability to use the 
error correction provision and that the EPA should impose meaningful 
limits on its ability to use this mechanism to effectuate significant 
changes to a prior action or to implement new policy perspectives. The 
EPA acknowledges the concern expressed by the commenters. The Agency 
intends the same intrinsic limits on its error correction authority 
that exist under CAA section 110(k)(6) to apply to its use under 
subpart Ba: the EPA must determine that its action on a state plan 
submission was ``in error.'' The EPA reviews state plan submissions 
against the applicable requirements of the statute, general 
implementing regulations, and specific EG. If the submission meets 
those requirements, it is ``satisfactory'' and the EPA must approve it. 
A subsequent change in Agency policy alone does not constitute an error 
that the EPA committed in acting on the state plan. The EPA's history 
of using error correction mechanisms under CAA section 110(k)(6), 
including to correct clerical or typographic errors and remove 
provisions from SIPs that it was without authority to approve in the 
first instance (as described earlier), gives good indication of how the 
EPA intends to use this mechanism under subpart Ba. The EPA also notes 
that use of error correction is fact- and context-specific, and a 
determination that a previous action was in error is subject to 
scrutiny and review by the state and public. Additionally, due to the 
complex facts and circumstances that frequently characterize state 
plans and state plan implementation, the EPA believes that any attempt 
to further define the circumstances in which use of error correction 
may or may not be permissible is likely to inadvertently limit its use 
where otherwise appropriate. Thus, the Agency does not find it 
necessary to prescribe further limits on its use of error correction 
under these CAA section 111 implementing regulations. The EPA is 
therefore finalizing use of error correction for state plan actions at 
40 CFR 60.27a(j) as proposed. While the EPA maintains that this error 
correction mechanism would be available for acting on state plans when 
appropriate, it also expects that it will work with states, as it has 
done previously in the SIP context, to correct any deficiencies in 
their plans.

E. Remaining Useful Life and Other Factors (RULOF) Provisions

    The EPA is finalizing revisions to certain provisions of 40 CFR 
60.24a to clarify the framework for applying standards of performance 
based on RULOF in state plans \63\ under CAA section 111(d). Consistent 
with Congress's mandate in CAA section 111(d), the EPA's implementing 
regulations have guided the implementation of RULOF for decades. See 40 
CFR 60.24(d), (f). The existing subpart Ba regulations \64\ contain 
provisions at 40 CFR 60.24a(e) governing the circumstances under which 
states may take RULOF into consideration when applying standards of 
performance to particular sources in state plans. The EPA proposed 
revisions to these existing provisions as well as additional RULOF-
related requirements to ensure consistency with the statute and to 
enhance clarity and equitable treatment for states. The EPA is 
finalizing some of these provisions as proposed, is finalizing other 
provisions with changes relative to proposal in response to public 
comments, and is choosing not to finalize yet other provisions.
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    \63\ As explained in section III.E.1. of this preamble, any 
discussion and requirements that apply to states' consideration of 
RULOF in state plans also apply to the EPA's consideration of RULOF 
in the context of a Federal plan.
    \64\ The D.C. Circuit's vacatur of certain provisions of subpart 
Ba in ALA did not impact the existing RULOF provision at 40 CFR 
60.24a(e).
---------------------------------------------------------------------------

    Section III.E.1. of this preamble describes the statutory and 
regulatory background of RULOF under CAA section 111 and section 
III.E.2. of this preamble explains the authority and rationale for the 
collective regulatory revisions. Section III.E.3. of this

[[Page 80509]]

preamble describes in detail the proposed RULOF provisions and the 
EPA's approach to each provision in this final rule.
1. Statutory and Regulatory Background
    Under CAA section 111(d), the EPA is required to ``establish a 
procedure . . . under which each State shall submit to the 
Administrator a plan which (A) establishes standards of performance 
for'' designated facilities and ``(B) provides for the implementation 
and enforcement of such standards of performance.'' As the Supreme 
Court explained in West Virginia v. EPA (in the context of an EG 
addressing existing power plants): ``Although the States set the actual 
rules governing existing power plans, EPA itself still retains the 
primary regulatory role in Section 111(d).'' \65\ The Court elaborated 
that the ``[t]he Agency, not the States, decides the amount of 
pollution reduction that must ultimately be achieved. It does so by 
again determining, as when setting the new source rules, `the best 
system of emission reduction . . . that has been adequately 
demonstrated for [existing covered] facilities.' 40 CFR part 
60.22(b)(5) (2021); see also 80 FR 64664, and n. 1. The States then 
submit plans containing the emissions restrictions that they intend to 
adopt and enforce in order not to exceed the permissible level of 
pollution established by EPA. See parts 60.23, 60.24; 42 U.S.C. part 
7411(d)(1).'' \66\
---------------------------------------------------------------------------

    \65\ 142 S. Ct. 2587, 2601-02 (2022).
    \66\ Id. The part of the rule preamble cited by the Court 
states, in part: ``Under CAA section 111(a)(1) and (d), the EPA is 
authorized to determine the BSER and to calculate the amount of 
emission reduction achievable through applying the BSER. The state 
is authorized to identify the emission standard or standards that 
reflect that amount of emission reduction.'' 80 FR 64662, 64664 n. 1 
(Oct. 23, 2015).
---------------------------------------------------------------------------

    Accordingly, while states establish the standards of performance 
for individual sources, EPA must ensure that such standards reflect the 
degree of emission limitation achievable through the application of the 
BSER. This obligation derives from the definition of ``standard of 
performance'' under CAA section 111(a)(1), which is ``a standard for 
emissions of air pollutants which reflects the degree of emission 
limitation achievable through the application of the best system of 
emission reduction which . . . the Administrator determines has been 
adequately demonstrated.'' Consistent with this definition, the EPA 
identifies the degree of emission limitation achievable through 
application of the BSER for a category (or sub-category) of existing 
sources as part of its EG. 40 CFR 60.22a(b)(5). States must then 
establish standards of performance for existing sources in their state 
plans that reflect the EPA's degree of emission limitation.
    CAA section 111(d)(1) also requires that the ``regulations which 
establish a procedure'' for submission of state plans must ``permit'' 
states, ``in applying a standard of performance to any particular 
source under a plan,'' to consider, ``among other factors, the 
remaining useful life of the existing source.'' Thus, while standards 
of performance must generally reflect the degree of emission limitation 
achievable through application of the BSER determined by the EPA 
pursuant to CAA section 111(a)(1), see 40 CFR 60.24a(c), CAA section 
111(d)(1) also contemplates circumstances in which states would be 
permitted to deviate from the degree of emission limitation in the 
applicable EG based on consideration of RULOF for particular sources.
    The 1970 version of CAA section 111(d) made no reference to the 
consideration of RULOF in the context of standards for existing 
sources.\67\ In the 1975 regulations promulgating subpart B to 
implement the 1970 CAA section 111(d), however, the EPA included a 
provision that would allow states to provide ``variances'' from the 
EPA's emission guideline on a case-by-case basis.\68\ For health-based 
pollutants, the regulations provided that states could apply a standard 
of performance less stringent than the EPA's EGs based on cost, 
physical impossibility, and other factors specific to a designated 
facility that would make the application of a less stringent standard 
significantly more reasonable. 40 CFR 60.24(f). For welfare-based 
pollutants, the regulations provided that states could apply a less 
stringent standard by balancing the requirements of an EG ``against 
other factors of public concern.'' 40 CFR 60.24(d).
---------------------------------------------------------------------------

    \67\ See Public Law 91-604, section 111(d)(1) (Dec. 31, 1970), 
84 Stat. 1684.
    \68\ 40 FR 53340, 53344 (Nov. 17, 1975).
---------------------------------------------------------------------------

    In proposing this variance provision, the EPA explained that the 
application of less stringent emission standards on a case-by-case 
basis is allowed, provided that sufficient economic justification is 
demonstrated in each case. Such justification must be presented for 
each case in the plan and may include, for example, unreasonable cost 
of control resulting from plant age, location, or basic process design 
or physical impossibility of installing specified control systems.\69\ 
In response to a comment received on its proposal arguing that the EPA 
did not have authority to promulgate a variance provision, the Agency 
explained that, although section 111(d) does not explicitly provide for 
variances, it does require consideration of the cost of applying 
standards to existing facilities. Such a consideration is inherently 
different than for new sources, because controls cannot be included in 
the design of an existing facility and because physical limitations may 
make installation of particular control systems impossible or 
unreasonably expensive in some cases. For these reasons, EPA believes 
the provision (Sec.  60.24(f)) allowing States to grant relief in cases 
of economic hardship (where health-related pollutants are involved) is 
permissible under section 111(d).\70\
---------------------------------------------------------------------------

    \69\ 39 FR 36102, 36102 (Oct. 7, 1974).
    \70\ 40 FR 53343.
---------------------------------------------------------------------------

    The Agency further explained in the 1975 rulemaking that the 
``EPA's emission guidelines will reflect its judgment of the degree of 
control that can be attained by various classes of existing sources 
without unreasonable costs.'' \71\ States were required to establish 
emission standards for existing sources that are equivalent to the 
EPA's emission guidelines; states would also be free to apply more 
stringent standards for particular sources within a class of sources 
that can achieve greater control without unreasonable costs, or where 
they otherwise believe that additional control is necessary or 
desirable.\72\
---------------------------------------------------------------------------

    \71\ Id.
    \72\ See id.
---------------------------------------------------------------------------

    As part of the 1977 CAA amendments, Congress amended CAA section 
111(d)(1) in a way that codified the provision of a variance as 
contained in the EPA's 1975 regulations. Specifically, Congress amended 
CAA section 111(d)(1) to require that the EPA's regulations under this 
section ``shall permit the State in applying a standard of performance 
to any particular source under a plan submitted under this paragraph to 
take into consideration, among other factors, the remaining useful life 
of the existing source to which such standard applies.'' The EPA 
considered the variance provision under subpart B to meet this 
requirement and did not revise the provision subsequent to the 1977 CAA 
amendments until the Agency promulgated new implementing regulations in 
2019 under subpart Ba. As part of the 2019 revisions, the EPA removed 
the health- and welfare-based pollutants distinction and collapsed the 
associated requirements of the previous variance provision into a 
single, then-

[[Page 80510]]

new RULOF provision.\73\ As did subpart B before it, this subsection 
provides that, in applying a standard of performance to a particular 
source, the state may take into consideration factors including the 
remaining useful life of such source, provided that the state 
demonstrates one or more of three circumstances: unreasonable cost of 
control resulting from plant age, location, or basic process design; 
physical impossibility of installing necessary control equipment; or 
other factors specific to the facility that make application of a less 
stringent standard or compliance time significantly more reasonable. 
The 2019 RULOF provision also allows, as did the 1975 version, for the 
variance to be provided for a particular facility or class of such 
facilities.
---------------------------------------------------------------------------

    \73\ 84 FR 32520, 32577 (July 8, 2019).
---------------------------------------------------------------------------

    CAA section 111(d)(2) provides that ``[t]he Administrator shall 
have the same authority . . . to prescribe a plan for a State in cases 
where the State fails to submit a satisfactory plan as he would have 
under section 7410(c) of this title [i.e., CAA section 110(c)] in the 
case of failure to submit an implementation plan.'' When CAA section 
111(d)(2) was enacted in 1970, CAA section 110(c) stated that the 
Administrator shall promptly propose a Federal implementation plan for 
a state if ``(1) the State fails to submit an implementation plan . . . 
within the time prescribed, (2) the plan, or any portion thereof, 
submitted for such State is determined by the Administrator not to be 
in accordance with the requirements of this section, or (3) the State 
fails, within 60 days after notification by the Administrator or such 
longer period as he may prescribe, to revise an implementation plan as 
required pursuant to a provision of its plan . . . .'' \74\
---------------------------------------------------------------------------

    \74\ Public Law 91-604, section 110(c) (Dec. 31, 1970), 84 Stat. 
1681-82.
---------------------------------------------------------------------------

    Thus, CAA section 111(d)(2), through its reference to CAA section 
110(c), provides the EPA the authority and the obligation to review 
state plans for compliance with CAA requirements.75 76 If a 
state has not submitted a state plan or if the EPA determines that a 
state plan is not ``satisfactory,'' i.e., not in accordance with the 
requirements of CAA section 111, the EPA must promulgate a Federal 
plan.
---------------------------------------------------------------------------

    \75\ See also 40 CFR 60.27(c) (``The Administrator will, after 
consideration of any State hearing record, promptly prepare and 
publish proposed regulations setting forth a plan, or portion 
thereof, for a State if: (1) The State fails to submit a plan within 
the time prescribed; . . . (3) The Administrator disapproves the 
State plan or plan revision or any portion thereof, as 
unsatisfactory because the requirements of this subpart have not 
been met.''); 60.27(d) (providing for promulgation of a proposed 
Federal plan).
    \76\ Congress subsequently updated CAA section 110(c) in 1977 
and again in 1990. The current version of CAA section 110 splits the 
EPA's Federal implementation plan authority and the criteria for 
disapproval of State implantation plans across subsections 110(c) 
and 110(k)(3). CAA section 110(c)(1) provides that ``[t]he 
Administrator shall promulgate a Federal implementation plan at any 
time within 2 years after the Administrator--'' (A) finds that a 
State has failed to make a complete plan submission, or ``(B) 
disapproves a State implementation plan submission in whole or in 
part, unless the State corrects the deficiency, and the 
Administrator approves the plan or plan revision, before the 
Administrator promulgates such Federal plan.'' CAA section 
110(k)(3), which addresses ``[f]ull and partial approval and 
disapproval,'' states that the Administrator shall approve all or 
certain portions of the plan that ``meet[] the applicable 
requirements of this chapter.'' Thus, a plan, or any portion 
thereof, that fails to meet the applicable CAA requirements must be 
disapproved.
---------------------------------------------------------------------------

    Congress further provided in CAA section 111(d)(2) that the EPA 
shall, in promulgating a standard of performance under a Federal plan, 
``take into consideration, among other factors, remaining useful lives 
of the sources in the category of sources to which such standard 
applies.'' Thus, the RULOF regulations the EPA has previously 
promulgated in subparts B and Ba, and the revisions to the RULOF 
regulations in subpart Ba being finalized in this action, apply not 
only to states when promulgating state plans, but also to the EPA when 
promulgating a Federal plan. Throughout this section III.E. of the 
preamble, discussion of provisions and requirements that apply to 
states' consideration of RULOF in state plans also apply to the EPA's 
consideration of RULOF in the context of a Federal plan.
2. Authority and Rationale for the Revisions
    The primary authority for these revisions is in CAA section 
111(d)(1). The rationale for the revisions finalized here is to more 
fully align the implementing regulations with the statute and to 
enhance clarity for states as well as the equitable treatment of states 
and sources.
    CAA section 111(d)(1) directs the EPA to ``prescribe regulations 
which establish a procedure'' under which states submit state plans. 
These regulations must ``permit'' states, in applying a standard of 
performance to any particular source, to consider RULOF. That is, 
Congress gave the EPA the authority and the obligation to establish 
procedures that permit states to consider RULOF.
    The EPA has been guiding consideration of RULOF for over fifty 
years, consistent with Congress's direction. ``Permit'' means ``to 
consent to formally; to allow (something) to happen, esp[ecially] by an 
official ruling, decision, or law.'' \77\ It is well understood that 
there may be parameters or rules as a condition of someone consenting 
to or allowing something to be done. For example, a building permit 
generally does not allow a person to build in any way they like, but 
contains conditions and requirements such as compliance with safety 
codes and limitations on height. In general, ``permit,'' whether a verb 
or noun, carries with it an expectation of rules and parameters 
designed to ensure consistency with the applicable framework, as 
opposed to open-ended discretion.\78\ CAA section 111(d)(1) provides 
that ``regulations of the Administrator . . . shall permit the State'' 
to consider RULOF (emphasis added). The natural reading of this 
provision is that Congress intended the EPA to set out parameters and 
conditions that govern states' consideration of RULOF..\79\
---------------------------------------------------------------------------

    \77\ Black's Law Dictionary (11th ed. 2019); see also The 
American College Dictionary (1970) (``to let (something) be done or 
occur''); Oxford English Dictionary Online (``to allow or give 
consent to (a person or thing) to do or undergo something''), 
https://www.oed.com/search/dictionary/?scope=Entries&q=permit, page 
accessed Sept. 1, 2023.
    \78\ See, e.g., U.S. v. Chau, 293 F.3d 96, 101 (3d Cir., 2002) 
(a provision requiring an entity to provide notice to the EPA prior 
to acting is not a ``permit'' because ``[a] requirement that someone 
provide written notice of an intention to perform an act is not the 
same at the EPA's granting of a license, or other permission, to the 
person to perform the act in question . . . .'').
    \79\ This contrasts with other provisions of the Clean Air Act 
where Congress granted states unbounded discretion. See, e.g., CAA 
section 116 (``nothing in this chapter shall preclude or deny the 
right of any State or political subdivision thereof to adopt or 
enforce'' more stringent requirements).
---------------------------------------------------------------------------

    The EPA's role in implementing RULOF finds further support in the 
Supreme Court's understanding of this provision as laid out in American 
Electric Power v. Connecticut.\80\ In describing the statutory 
framework of CAA section 111, the Court explained that the EPA sets 
standards of performance based on CAA section 111(a)(1). It further 
recognized that, pursuant to the EPA's subpart B general implementing 
regulations for state plans, 40 CFR 60.24(f), ``EPA may permit state 
plans to deviate from generally applicable emissions standards upon 
demonstration that costs are `[u]n-reasonable.' '' \81\
---------------------------------------------------------------------------

    \80\ 564 U.S. 410 (2011).
    \81\ Id. at 427.
---------------------------------------------------------------------------

    At the same time that Congress clearly directed the EPA to 
prescribe rules governing states' consideration of RULOF, it also 
provided that those rules establish a procedure under which

[[Page 80511]]

states submit state plans, including any standards of performance 
pursuant to consideration of RULOF. CAA section 111(d)(1) states, ``The 
Administrator shall prescribe regulations which shall establish a 
procedure . . . . Regulations of the Administrator under this paragraph 
shall permit the State in applying a standard of performance to any 
particular source . . . to take into consideration, among other 
factors, the remaining useful life of the existing source to which such 
standard applies.'' Consistent with this statutory direction, the EPA's 
RULOF provisions, both the existing provisions and those being 
finalized in this action, are fundamentally procedural in nature. They 
prescribe the series of steps and considerations states must undertake 
to apply a less stringent standard of performance that is consistent 
with CAA section 111(d).
    As discussed in section III.E.1. of this preamble, Congress also 
granted the EPA a role in ensuring that states applying standards of 
performance based on RULOF do so in an appropriate manner. CAA section 
111(d)(2) requires the EPA to evaluate standards of performance in 
state plans and approve them only if they are ``satisfactory,'' i.e., 
if they meet the applicable requirements.\82\ Thus, while states have 
responsibility for establishing, implementing, and enforcing standards 
of performance for designated facilities, the EPA has an obligation to 
ensure that those standards of performance--including any standards of 
performance based on consideration of RULOF--are consistent with the 
statute. The regulations the EPA is promulgating in this final rule 
provide greater clarity and thus enable states to apply less stringent 
standards of performance that are consistent with CAA section 111(d). 
Having clear, detailed regulations also aids the EPA in evaluating less 
stringent standards of performance included in state plans, which 
maximizes the Agency's ability to provide for fair and equitable 
treatment across the states and sources that use the RULOF provision.
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    \82\ CAA section 111(d)(2)(A) authorizes the EPA to promulgate a 
Federal plan for any state that ``fails to submit a satisfactory 
plan'' under section 111(d)(1). Accordingly, the EPA interprets 
``satisfactory'' as the standard by which the EPA reviews state plan 
submissions. The EPA discusses the ``satisfactory'' standard of 
review in greater detail in section III.E.3.b of this preamble.
---------------------------------------------------------------------------

    In addition, the parameters for considering RULOF set out in this 
final rule are consistent with the role of RULOF as an important tool 
for states in the unusual circumstance in which the EPA's BSER 
determination is unreasonable for a particular source. As explained in 
detail in section III.E.3.b. of this preamble, the EPA's longstanding 
interpretation is that RULOF provision in CAA section 111(d)(1) allows 
the Agency to permit states to provide variances for existing 
facilities in certain circumstances. These circumstances are limited to 
when a state can demonstrate that it is unreasonable for a particular 
facility to achieve the degree of emission limitation determined by the 
EPA in the applicable EG.
    Under CAA section 111, EPA must provide BSER and degree of emission 
limitation determinations that are, to the extent reasonably 
practicable, applicable to all designated facilities in the source 
category. In many cases, this requires the EPA to create subcategories 
of designated facilities, each of which has a BSER and degree of 
emission limitation \83\ tailored to its circumstances.\84\ Thus, the 
EPA endeavors, to the extent practicable, to promulgate BSER and degree 
of emission limitation determinations that are achievable for all 
designated facilities covered by an EG. However, as Congress 
recognized, this may not be possible in every instance because, e.g., 
it is not be feasible for the Agency to know and consider the 
idiosyncrasies of every designated facility in a source category or 
because the circumstances of individual facilities change after the EPA 
determined the BSER. The EPA believes Congress intended RULOF to allow 
the EPA to permit the use of variances for states to adjust a standard 
of performance in unusual circumstances in which the EPA's 
determination regarding the degree of emission limitation achievable 
through the BSER is not reasonable for a particular designated 
facility.
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    \83\ The EPA, in different contexts, uses the phrase ``degree of 
emission limitation'' to refer to both the degree of emission 
limitation achievable through application of the BSER at the level 
of an individual source, e.g., the best system can achieve an 85% 
reduction in end-of-stack emissions when applied to a designated 
facility, and to the overall level of stringency that results from 
applying the BSER to the source category as a whole. In this section 
of the preamble, this phrase refers to the emission reductions that 
are achievable at an individual source.
    \84\ See 40 CFR 60.22a(b)(5) (EPA may specify different degrees 
of emission limitation and compliance times for different 
subcategories of designated facilities).
---------------------------------------------------------------------------

    This view of the RULOF provision as a limited variance from the 
EPA's determinations in an EG has a long history. The EPA's description 
of how it develops EGs in the preamble to the 1975 subpart B 
implementing regulations stated that ``emission guidelines will reflect 
subcategorization within source categories where appropriate, taking 
into account differences in sizes and types of facilities and similar 
con- . . . siderations [sic], including differences in control costs 
that may be involved for sources located in different parts of the 
country.'' \85\ As a result, emission guidelines ``will in effect be 
tailored to what is reasonably achievable by particular classes of 
existing sources, and States will be free to vary from the levels of 
control represented by the emission guidelines in the ways mentioned 
above.'' \86\ The ``ways mentioned above'' included establishing more 
stringent standards under CAA section 116 where states believe 
additional control is necessary or desirable, as well as setting more 
lenient standards, subject to EPA review, in cases of economic 
hardship.\87\ The EPA subsequently explained that such cases could 
arise because controls were not included in the design of existing 
sources or because physical limitations may make installation of 
particular control systems impossible or unreasonably expensive in some 
cases.\88\
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    \85\ 40 FR 53343.
    \86\ Id.
    \87\ See id.
    \88\ Id. at 53344. Similarly, in the 1974 notice of proposed 
rulemaking for the subpart B regulations, the EPA explained that 
``it is the Administrator's judgment that section 111(d) permits him 
to approve State emission standards only if they reflect application 
of the best systems of emission reduction (considering the cost of 
such reduction) that are available.'' The EPA further stated: ``It 
is recognized, however, that application of such standards may be 
unreasonable in some situations. For example, to require that 
existing controls be upgraded by a small margin at a relatively high 
cost may be unreasonable in some cases. The proposed regulations, 
therefore, provide that States may establish less stringent emission 
standards on a case-by-case basis provided that sufficient 
justification is demonstrated in each case.'' 39 FR 36102, 36102 
(Oct. 7, 1974).
---------------------------------------------------------------------------

    Thus, the EPA's long-standing interpretation is that the standards 
of performance established by states must generally reflect the degree 
of emission limitation determined by the Agency, except where, based on 
RULOF, states provide ``sufficient justification'' that the EPA's 
determination is ``unreasonable'' for a particular source.\89\ Although 
the EPA endeavors to address the circumstances of all designated 
facilities in its EG, there may remain instances in which the 
circumstances of a particular facility justify application of a less 
stringent standard of performance.
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    \89\ 39 FR 36102; see also 40 CFR 60.24(c), (f) (EPA's 
longstanding regulations in subpart B require standards of 
performance in state plans to be no less stringent than the 
corresponding EG except where a state has satisfied the regulatory 
requirements for invoking RULOF).

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[[Page 80512]]

    Finally, and relatedly, to be consistent with the statutory purpose 
of reducing dangerous air pollution under CAA section 111; the 
statutory framework under which to achieve that purpose the EPA is 
directed to set the degree of emission limitation achievable through 
application of the best system of emission reduction; and the history 
of the statutory RULOF provision as a limited variance from that degree 
of emission limitation to address unusual circumstances at particular 
facilities, the EPA's regulations must ensure that application of less 
stringent standards of performance pursuant to consideration of RULOF 
does not undermine the degree of emission limitation achievable through 
application of the BSER.
    Thus, for the reasons explained above, the EPA has the authority to 
promulgate the regulatory updates included in this final rule, which 
flow from the statute's direction for the Agency to ``establish 
procedures'' that, among other things, ``permit'' states to consider 
RULOF. The EPA believes these updates are warranted to provide 
additional clarity to the states (when developing state plans) and the 
EPA (when issuing Federal plans and reviewing state plans) regarding 
the appropriate procedures for considering RULOF and to ensure the 
predictable and equitable treatment of states and sources in 
implementing EGs under CAA section 111(d). Furthermore, the updates to 
the framework are needed to ensure that consideration of RULOF adheres 
to statutory purpose, structure, and historical context discussed 
above.
    Critically, the regulatory revisions also provide a framework for 
how states and the EPA calculate and apply less-stringent standards of 
performance. Neither the RULOF provision in subpart B nor the 2019 
update to that provision in subpart Ba clearly delineate the process 
for states or the EPA after they have determined that a source cannot 
reasonably achieve the degree of emission limitation in the applicable 
emission guideline. As such, the existing regulations are not adequate 
to ensure that standards of performance pursuant to RULOF are no less 
stringent than required to address the basis for providing a variance 
from the EPA's degree of emission limitation in the first instance.
    Consistent with the long-held interpretation of the RULOF provision 
as a limited variance, the EPA is aware of only a small handful of 
instances in which a state has used this provision to apply a less-
stringent standard of performance to a designated facility in a state 
plan. In three of these instances, the Agency approved less stringent 
standards of performance for welfare-related designated pollutants for 
which, under subpart B (40 CFR 60.24(d)), there was a lower bar for 
doing so.\90\ In the fourth instance, the state invoked RULOF to apply 
a less-stringent standard for a health-related designated pollutant and 
the EPA disapproved the less-stringent standard for failing to satisfy 
the requirements of 40 CFR 60.24(f).\91\ At the time of this 
rulemaking, however, there are two new EGs for which rulemaking is 
ongoing; each of these EGs would address large, complex, and highly 
diverse source categories.\92\ Commenters on these proposed EGs have 
suggested that there may be more of a role for RULOF than in past 
EGs.\93\ The revisions to the RULOF provisions are thus timely to give 
states greater clarity on and predictability for applying less 
stringent standards of performance consistent with CAA section 111.
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    \90\ 49 FR 35771 (Sept. 12, 1984), 47 FR 50868 (Nov. 10, 1982), 
47 FR 28099 (June 29, 1982). See, e.g., Emission Guideline Document 
for Kraft Pulping: Control of TRS Emissions from Existing Mills, 
EPA-450/2-78-003b (March 1979) at 1-3 (``For Welfare-related 
pollutants, states may balance the emission guidelines, times for 
compliance, and other information in a guideline document against 
other factors of public concern in establishing emission standards, 
compliance schedules, and variances provided that appropriate 
consideration is given to the information presented in the guideline 
document and at public hearing(s) required by Subpart B and that all 
other requirements of Subpart B are met. . . . Thus, states will 
have substantial flexibility to consider factors other than 
technology and costs in establishing plans for the control of 
welfare-related pollutants if they wish.'').
    \91\ See 40 CFR 62.8860(a) (``The requirements of Sec.  60.24(f) 
of this chapter are not met because the State failed to justify the 
application of emission standards less stringent than the Federal 
emission standards.''); see also 55 FR 19883, 19884 (May 14, 1990) 
(explaining the proposed less-stringent limits were not approvable 
because the state had not demonstrated sufficient justification). 
The RULOF provision that governed that action in subpart B was 
substantively identical to the version promulgated in 2019 in 
subpart Ba.
    \92\ Proposed Rule: ``Standards of Performance for New, 
Reconstructed, and Modified Sources and Emissions Guidelines for 
Existing Sources: Oil and Natural Gas Sector Climate Review,'' 86 FR 
63110 (Nov. 15, 2021); Supplemental Proposal: Standards of 
Performance for New, Reconstructed, and Modified Sources and 
Emissions Guidelines for Existing Sources: Oil and Natural Gas 
Sector Climate Review,'' 87 FR 74702 (Dec. 6, 2022); Proposed Rule: 
New Source Performance Standards for Greenhouse Gas Emissions From 
New, Modified, and Reconstructed Fossil Fuel-Fired Electric 
Generating Units; Emission Guidelines for Greenhouse Gas Emissions 
From Existing Fossil Fuel-Fired Electric Generating Units; and 
Repeal of the Affordable Clean Energy Rule,'' 88 FR 33240 (May 23, 
2023).
    \93\ See, e.g., Comment Letter of Pioneer Natural Resources USA, 
Inc. on Supplemental Notice of Proposed Rulemaking for Standards of 
Performance for New, Reconstructed, and Modified Sources and 
Emissions Guidelines for Existing Sources: Oil and Natural Gas 
Sector (``Oil and Gas Proposed Rule''), EPA-HQ-OAR-2021-0317-2298 at 
20-21; Comment Letter of American Petroleum Institute on Oil and Gas 
Proposed Rule, EPA-HQ-OAR-2021-0317-2428 at 93-95, 102-104; Comment 
Letter of Power Generators Air Coalition on New Source Performance 
Standards for Greenhouse Gas Emissions from New, Modified, and 
Reconstructed Fossil Fuel-Fired Electric Generating Units; Emission 
Guidelines for Greenhouse Gas Emissions from Existing Fossil Fuel 
Fired Electric Generating Units; and Repeal of the Affordable Clean 
Energy Rule (``EGU Proposed Rule''), EPA-HQ-OAR-2023-0072-0710 at 
75-78; Comment Letter of Wisconsin Department of Natural Resources 
and Public Service Commission of Wisconsin on EGU Proposed Rule, 
EPA-HQ-OAR-2023-0072-0538 at 1-2, 10-11.
---------------------------------------------------------------------------

    Note that the RULOF provisions are distinct from the flexible 
compliance mechanisms such as trading and averaging, discussed in 
section III.G.1. of this preamble. The RULOF provisions apply where a 
state intends to depart from the degree of emission limitation in the 
EG and propose a less stringent standard for a designated facility (or 
class of facilities). That is, the RULOF provisions are relevant to a 
state's process of applying a standard of performance to a designated 
facility in the first instance. In contrast, trading and averaging are 
mechanisms that, when permitted in an EG, states may use to demonstrate 
compliance with the standards of performance that are contained within 
their state plans.
3. Proposed and Finalized RULOF Provisions
    The EPA proposed revisions to the existing RULOF provision at 40 
CFR 60.24a(e), which details the circumstances under which states or 
the EPA may apply a less stringent standard of performance. The EPA 
also proposed to add new provisions: a procedure for determining less 
stringent standards when a state has properly invoked RULOF (proposed 
and finalized at 40 CFR 60.24a(f)); a clarification that state plans 
may not apply less stringent standards if a designated facility can 
reasonably achieve the presumptive standard of performance using a 
technology other than the BSER (proposed at 40 CFR 60.24a(g)); a 
clarification that any less stringent standards must meet all other 
applicable requirements (proposed at 40 CFR 60.24a(l), finalized at 
60.24a(h)); requirements related to when operating conditions that are 
relied on for a less stringent standard must be included as enforceable 
requirements in state plans (proposed at 40 CFR 60.24a(h), finalized at 
40 CFR 60.24a(g)); requirements related to the consideration of 
remaining useful life (proposed 40 CFR 60.24a(i)); a clarification 
regarding the burden of proof and information on which RULOF 
demonstrations are based (proposed 40 CFR 60.24a(j));

[[Page 80513]]

requirements to consider potential impacts and benefits of control to 
communities most affected by and vulnerable to emissions from a 
designated facility for which a state is proposed a less stringent 
standard (proposed 40 CFR 60.24a(k)); and a clarification that states 
may account for other factors in applying a more stringent standard of 
performance (proposed 40 CFR 60.24a(m)). In addition, the EPA proposed 
changes to the existing 40 CFR 60.24a(f) (proposed at 40 CFR 60.24a(n), 
finalized at Sec.  60.24(i)) reflecting the Agency's revised 
interpretation that CAA sections 111(d) and 116 authorize states to 
include standards of performance more stringent than the EPA's 
presumptive standards in their state plans as enforceable requirements.
    The EPA received a wide range of comments on its proposed RULOF 
provisions. Some commenters expressed support for the proposed 
revisions, noting that the EPA has the authority to specify how RULOF 
is implemented and the obligation to ensure that its use does not 
undermine the emission reductions that are achievable through 
application of the BSER. Supportive commenters also noted that 
providing a regulatory structure is important to ensure that RULOF is 
applied in a reliable, consistent, and appropriate manner. Commenters 
opposed to the proposed RULOF revisions stated that there is no basis 
in the statute for the EPA to restrict states' authority to consider 
RULOF and apply less-stringent standards of performance. Some 
commenters also argued that the EPA's proposed regulations were too 
prescriptive and burdensome. Other commenters generally supported the 
EPA's proposed revisions but had questions or concerns regarding 
specific provisions, including the requirements around source-specific 
standards of performance and consideration of impacted communities. One 
commenter requested that the EPA clarify that the revised RULOF 
provisions would apply to design, equipment, work practice, or 
operational standards issued under CAA sections 111(d) and 111(h)(1).
    After consideration of these comments, the EPA is finalizing a 
subset of the requirements that it proposed. As a general matter, the 
EPA is finalizing as requirements the provisions that must apply under 
any EG to provide necessary clarity to both the states and the EPA in 
applying or approving less stringent standards of performance. This 
clarity and predictability with regard to what constitutes a 
satisfactory, and therefore approvable, less stringent standard is 
crucial to ensuring the equitable treatment of states and sources that 
are considering RULOF in state plans. The requirements the EPA is 
finalizing are additionally necessary to ensure that use of RULOF is 
consistent with the statutory purpose of reducing emissions of 
dangerous air pollutants, the framework under which the EPA is directed 
to achieve that purpose through determining the degree of emission 
limitation, and history of RULOF as a limited variance to address 
unusual circumstances when it is not possible for a particular facility 
to achieve the EPA's degree of emission limitation. The proposed RULOF 
provisions that are not being included as regulatory requirements 
remain important considerations when applying RULOF; however, the EPA 
is not finalizing them in these general implementing regulations.
    The EPA recognizes that in finalizing these updates it is imposing 
certain requirements on states' use of RULOF. Consistent with the 
framework of cooperative federalism under which CAA section 111(d) 
operates, states apply standards of performance pursuant to 
consideration of RULOF, as well as provide the compliance measures for 
implementing such standards, subject to the applicable statutory 
requirements. The Agency again notes that it has placed requirements on 
states' ability to apply less stringent standards of performance since 
it first created a variance provision in subpart B in 1975. See 40 CFR 
60.24(c) through (e). When Congress later adopted the RULOF provision 
into the statute, it directed the EPA in CAA section 111(d)(1) to 
establish a procedure permitting states to consider RULOF. Moreover, as 
discussed further in section III.E.3.b, these updates are consistent 
with the historical interpretation of RULOF as a variance from the 
EPA's degree of emission limitation. The EPA also notes that the 
requirements being finalized in this action establish a process for 
states in applying less stringent standards of performance. These final 
regulations ensure, consistent with the statutory purpose, that any 
less stringent standards are no less stringent than necessary to 
address the reason that the variance is needed in the first place.
    Finally, the EPA confirms that the RULOF provisions, including 
those being finalized in this action, apply to standards of performance 
promulgated pursuant to CAA sections 111(d) and 111(h)(1). The existing 
definition of ``standard of performance'' in 40 CFR 60.21a(f) includes 
``a legally enforceable regulation . . . prescribing a design, 
equipment, work practice, or operational standard, or combination 
thereof.'' Therefore, the RULOF provisions in 40 CFR 60.24a, which may 
be invoked to apply a ``standard of performance'' to a particular 
designated facility, also apply to standards of performance applied 
under CAA section 111(h)(1).\94\
---------------------------------------------------------------------------

    \94\ See also 40 CFR 60.24a(b).
---------------------------------------------------------------------------

a. Threshold Requirements for Considering Remaining Useful Life and 
Other Factors
    The existing RULOF provision at 40 CFR 60.24a(e) addresses the 
circumstances in which states may invoke RULOF to deviate from the BSER 
and degree of emission limitation determinations the EPA has made 
pursuant to CAA section 111(a)(1). It allows states to consider RULOF 
to apply a less stringent standard of performance for a designated 
facility or class of facilities if they demonstrate one of the three 
following circumstances: (1) unreasonable cost of control resulting 
from plant age, location, or basic process design; (2) physical 
impossibility of installing necessary control equipment; or (3) other 
factors specific to the facility (or class of facilities) that make 
application of a less stringent standard or final compliance time 
significantly more reasonable.
    As discussed in the notice of proposed rulemaking, the proposed 
amendments largely retained this provision, including the three 
circumstances under which a less stringent standard of performance may 
be applied, and provided further clarification of what a state must 
demonstrate in order to invoke RULOF in a state plan. Specifically, the 
proposed amendments required the state to demonstrate that a particular 
facility cannot reasonably apply the BSER to achieve the degree of 
emission limitation determined by the EPA, based on one or more of the 
three circumstances. The EPA's proposal retained the first circumstance 
in whole and revised the second circumstance to add the ``technical 
infeasibility'' of installing a control as another situation in which 
application of RULOF may be appropriate. The proposal further clarified 
the third circumstance for invoking RULOF, the existing version of 
which provides that states may invoke RULOF when other factors specific 
to the facility make a less stringent standard of performance 
``significantly more reasonable.'' The EPA proposed to revise this 
circumstance, under which the first two circumstances also fall, to 
specify that states may consider RULOF

[[Page 80514]]

to apply a less stringent standard if circumstances specific to a 
facility are fundamentally different from the information the EPA 
considered in determining the BSER. This proposed clarification was 
intended to provide clear parameters for developing and assessing state 
plans, as the existing third circumstance is vague and potentially 
open-ended.
    The EPA explained at proposal that the revisions clarified the 
RULOF provision by tethering a state's RULOF demonstration to the 
statutory factors the EPA considered in the BSER determination. As 
discussed in section III.E.1. of this preamble, CAA section 111(a)(1) 
gives the EPA the responsibility of determining the BSER and degree of 
emission limitation that is required of designated facilities in the 
source category; the EPA endeavors, to the extent reasonably 
practicable based on the information before it, to promulgate 
determinations that are achievable for every designated facility 
covered by an EG. Per the statutory requirements, the EPA determines 
the BSER by first identifying control methods that it considers to be 
adequately demonstrated and then determining which is the best system 
of emission reduction by evaluating the statutory factors: (1) the cost 
of achieving such reduction, (2) nonair quality health and 
environmental impacts, (3) energy requirements, and (4) the amount of 
emission reductions.\95\ The EPA's BSER determination thus represents a 
system that is ``adequately demonstrated'' and reasonable for sources 
broadly within the source category; CAA section 111(a)(1) requires that 
standards of performance must reflect the degree of emission limitation 
that is achievable through application of the BSER.
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    \95\ Although CAA section 111(a)(1) may be read to state that 
the factors enumerated in the parenthetical are part of the 
``adequately demonstrated'' determination, the D.C. Circuit's case 
law may be read to treat them as part of the ``best'' determination. 
See Sierra Club v. Costle, 657 F.2d 298, 330 (D.C. Cir. 1981). Under 
either approach, the EPA's analysis and ultimate determination as to 
the BSER would be the same. In determining the ``best'' system of 
emission reduction, the EPA also considers the advancement of 
technology, consistent with D.C. Circuit caselaw. See id. at 347.
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    In considering the BSER, the D.C. Circuit has stated that to be 
``adequately demonstrated,'' the system must be ``reasonably reliable, 
reasonably efficient, and . . . reasonably expected to serve the 
interests of pollution control without becoming exorbitantly costly in 
an economic or environmental way.'' Essex Chem. Corp. v. Ruckelshaus, 
486 F.2d 427, 433 (D.C. Cir. 1973). Thus, in making the BSER 
determination, the EPA must evaluate whether a system of emission 
reduction is ``adequately demonstrated'' for the source category or 
sub-category based on the physical possibility and technical 
feasibility of control. Similarly, the court has interpreted CAA 
section 111(a)(1) as using reasonableness in light of the statutory 
factors as the standard in evaluating cost, so that a control 
technology may be considered the ``best system of emission reduction . 
. . adequately demonstrated'' if its costs are reasonable (i.e., not 
exorbitant, excessive, or greater than the industry can bear), but 
cannot be considered the BSER if its costs are unreasonable.\96\ In 
light of the statutory factors the EPA is required to consider, it 
follows that most designated facilities within the source category or 
subcategory should be able to implement the BSER at a reasonable cost 
to achieve the degree of emission limitation determined by the EPA. 
Consideration of RULOF is appropriate only for particular sources for 
which implementing the BSER to achieve that degree of emission 
limitation would impose unreasonable costs or would otherwise not be 
feasible due to facility-specific circumstances that are not applicable 
to the broader source category (or subcategories) and that the EPA did 
not consider in determining the BSER.
---------------------------------------------------------------------------

    \96\ See Lignite Energy Council v. EPA, 198 F.3d 930, 933 (D.C. 
Cir. 1999), Sierra Club v. Costle, 657 F.2d 298, 343 (D.C. Cir. 
1981), Portland Cement Ass'n v. EPA, 513 F.2d 506, 508 (D.C. Cir. 
1975).
---------------------------------------------------------------------------

    For example, if the EPA applied a specific cost threshold in 
determining the BSER, application of RULOF based on cost would only be 
appropriate where the cost of achieving the associated degree of 
emission limitation at a particular designated facility is unreasonably 
high relative to the costs the EPA considered for the BSER. Or, by way 
of further example, if the EPA were to determine that a specific back-
end control technology is adequately demonstrated and the BSER for a 
source category, a state may need to evaluate whether it would be 
physically possible to install that control technology at a designated 
facility given the particular size and physical constraints of that 
facility. Application of RULOF to deviate from the EPA's determinations 
pursuant to CAA section 111(a)(1) may be appropriate, e.g., where the 
state could show that the cost of achieving the degree of emission 
limitation would be significantly higher at a specific designated 
facility than the cost-per-ton EPA considered in setting the BSER, or 
that a specific designated facility does not have adequate space to 
reasonably accommodate the installation of the BSER and the facility 
cannot reasonably achieve the degree of emission limitation using a 
different control technology. The EPA proposed to require states to hew 
to the same types of factors and analyses the EPA's considered in its 
BSER determination when demonstrating that the EPA's determinations are 
not reasonable for a particular designated facility; the Agency 
explained that this would be consistent with the statutory framework 
under which RULOF is a limited exception to the level of stringency 
otherwise required by the BSER.\97\
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    \97\ 87 FR 79199.
---------------------------------------------------------------------------

    Related to the proposed revisions at 40 CFR 60.24a(e), the EPA also 
proposed to add new Sec.  60.24a(g) to the regulations, which would 
explicitly provide that a state plan may not apply a less stringent 
standard of performance in cases where a designated facility cannot 
reasonably apply the BSER to achieve the degree of emission limitation 
determined by the EPA, but can reasonably implement a different 
technology or other system to achieve that same degree of emission 
limitation. This is consistent with the statutory framework, which does 
not require sources to implement the EPA's BSER but rather permits 
states to allow their sources to comply with their standards of 
performance using systems of their choosing.
    The EPA received a range of comments on the proposed revisions to 
the threshold circumstances for invoking RULOF to apply a less-
stringent standard of performance. Some commenters agreed with the EPA 
that the existing criteria are not specific or clear enough to ensure 
that RULOF is invoked only when a designated facility cannot achieve 
the degree of emission limitation that the EPA has determined pursuant 
to section 111(a)(1). Several commenters supported the EPA's proposal 
that application of RULOF is only appropriate where a facility cannot 
reasonably apply the BSER to achieve the degree of emission limitation 
determined by the EPA based on fundamental differences between that 
facility and the factors the EPA considered in the BSER determination. 
Some commenters also urged the EPA to explicitly apply the 
``fundamentally different'' standard to all three circumstances under 
40 CFR 60.24a(e).
    However, other commenters argued that the EPA cannot preclude 
states from considering factors specific to particular facilities on 
the basis that the EPA did not consider those factors in

[[Page 80515]]

determining the BSER, and that the ``fundamentally different'' standard 
unlawfully narrows states' consideration of site-specific factors under 
the third RULOF criterion. Some commenters further contended that 
states should have wide latitude and flexibility to consider RULOF and 
that the EPA lacks authority to restrict states' abilities to apply 
RULOF in circumstances they deem appropriate. The EPA also received a 
request from one commenter asking the Agency to clarify how the 
proposed provisions at 40 CFR 60.24a(e) and (g) interact with each 
other.
    The EPA is finalizing the provisions for invoking RULOF at 40 CFR 
60.24a(e) with clarifying revisions relative to proposal. Based on 
these changes, the proposed addition of 40 CFR 60.24a(g) is redundant; 
the EPA is therefore not finalizing this provision.
    These revisions to 40 CFR 60.24a(e) are necessary to ensure that 
state plans comply with CAA section 111(d). As explained above, the 
EPA's determination of the degree of emission limitation achievable 
through application of the BSER is the level of stringency required by 
CAA section 111(d), unless it can be demonstrated that something about 
the EPA's determination does not hold true for a particular designated 
facility. The enumerated circumstances for invoking RULOF in 40 CFR 
60.24a(e) mirror the information the EPA considers in making its BSER 
and degree of emission limitation determination pursuant to CAA section 
111(a)(1): information related to determining that a system is 
adequately demonstrated (including physical possibility and technical 
feasibility), the cost of achieving emission reductions, and other 
factors, which include nonair quality health and environmental impacts 
and energy requirements. Thus, the long-standing RULOF provision \98\ 
is formulated for states to examine, at a minimum, the same factors the 
EPA considered in determining the BSER in order to determine the 
reasonableness of the EPA's BSER and degree of emission limitation as 
it applies to a particular designated facility. In this action, the EPA 
is clarifying the circumstances in 40 CFR 60.24a(e) for invoking RULOF 
in order to provide more objective and consistent criteria that will 
aid both states and the EPA in developing and reviewing standards of 
performance consistent with CAA section 111(d), as well as ensure the 
equitable treatment of states and sources that avail themselves of the 
RULOF provision.
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    \98\ The circumstances for invoking RULOF in the existing 
subpart Ba provision at 40 CFR 60.24a(e) are identical to those in 
the original variance provision of subpart B at 40 CFR 60.24(f).
---------------------------------------------------------------------------

    The EPA disagrees with commenters who argued that the proposed 
revisions to the third circumstance unlawfully constrain states' 
authority to invoke RULOF. On the contrary, the EPA believes these 
revisions provide necessary clarity to ensure that states invoke RULOF 
in appropriate circumstances. First, as discussed more fully in section 
III.E.2. of this preamble, Congress directed the EPA to promulgate 
regulations for the submission of state plans that ``permit'' states to 
consider RULOF. Rather than granting states unfettered discretion to 
consider RULOF in applying standards of performance, the statute 
directs the EPA to establish regulations describing the ``permissible'' 
use of such consideration. Thus, the EPA has the authority and 
obligation to guide states' consideration of RULOF.
    Second, the revisions to 40 CFR 60.24a(e) provide a clear and 
easily replicable standard for when it is appropriate to apply a less 
stringent standard of performance: when there are fundamental 
differences between the information the EPA considered in determining 
the degree of emission limitation and the information specific to a 
facility that make the EPA's degree of emission limitation unreasonable 
for the facility. In addition to clarifying the circumstances under 
which consideration of RULOF is appropriate, this standard also 
provides greater specificity that will aid both states and the EPA in 
implementing the provision. This standard is further consistent with 
statutory purpose, structure, and history of CAA section 111(d), under 
which the generally applicable requirement is the degree of emission 
limitation determined by the EPA and RULOF serves as a variance to that 
requirement.\99\ Moreover, the revisions to 40 CFR 60.24a(e) will 
provide a framework for the EPA to use when considering any requests 
for less stringent standards of performance when the Agency is 
promulgating a Federal plan, which is again critical to ensuring both 
the equitable treatment of states and sources and the integrity of an 
EG's emission reduction purpose.
---------------------------------------------------------------------------

    \99\ See the discussion in section III.E.3.b. of this preamble.
---------------------------------------------------------------------------

    This revision will additionally provide the EPA with clear criteria 
to use when evaluating any invocation of RULOF in state plans to 
determine whether providing a less-stringent standard of performance is 
consistent with the statutory framework and therefore approvable as 
``satisfactory.'' As noted above, it provides an objective, replicable 
benchmark against which to assess states' plans, which can be further 
elaborated on in individual EGs.
    The ``fundamentally different'' standard ensures that RULOF is 
invoked for circumstances where application of the statutory factors 
would lead to a result that is outside the realm of what the EPA 
considered reasonable in determining the BSER. The EPA makes BSER 
determinations on a source category, or sub-category, basis. 
Necessarily, therefore, the Agency considers information relevant to 
potential BSERs for representative, average units or as average values 
for the set of designated facilities. Implicit in an EPA determination 
that a system is the BSER based on average, representative information 
is a determination that values around those average representative 
values are also reasonable, including some portion of unit-specific 
values that will deviate from but are not significantly different than 
the average representative values. Therefore, in order to justify 
deviating from the EPA-determined degree of emission limitation, the 
circumstances of a particular source must be not just different but 
fundamentally different from those the Agency considered in determining 
the BSER.
    Furthermore, as explained at proposal, the ``fundamentally 
different'' standard is also consistent with other variance provisions 
that courts have upheld for environmental statutes. For example, in 
Weyerhaeuser Co. v. Costle,\100\ the court considered a regulatory 
provision promulgated under the Clean Water Act (CWA) that permitted 
owners to seek a variance from the EPA's national effluent limitation 
guidelines under CWA sections 301(b)(1)(A) and 304(b)(1). The EPA's 
regulation permitted a variance where an individual operator 
demonstrates a ``fundamental difference'' between a CWA section 
304(b)(1)(B) factor at its facility and the EPA's regulatory findings 
about the factor ``on a national basis.'' \101\ The court upheld this 
standard as ensuring a meaningful opportunity for an operator to seek 
dispensation from a limitation that would demand more of the individual 
facility than of the industry generally, but also noted that such a 
provision is not a license for avoidance of the Act's strict pollution 
control requirements.\102\
---------------------------------------------------------------------------

    \100\ 590 F.2d 1011 (D.C. Cir. 1978).
    \101\ Id. at 1039.
    \102\ Id. at 1035.

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[[Page 80516]]

    The EPA is revising the regulatory text of 40 CFR 60.24a(e) 
relative to proposal to explicitly provide that the ``fundamentally 
different'' standard applies to all three categories of circumstances 
for invoking RULOF. This change is consistent with the stated intent at 
proposal; for example, the EPA proposed ``to require that, in order to 
demonstrate that a designated facility cannot reasonably meet the 
presumptive level of stringency based on one of these three criteria, 
the state must show that implementing the BSER is not reasonable for 
the designated facility due to fundamental differences between the 
factors the EPA considered in determining the BSER, such as cost and 
technical feasibility of control and circumstances at the designated 
facility.'' \103\ As explained above, in order to be consistent with 
the statutory framework, the fundamentally different standard 
necessarily applies to any consideration that may be cause to invoke 
RULOF to provide a less-stringent standard of performance.
---------------------------------------------------------------------------

    \103\ 87 FR 79199.
---------------------------------------------------------------------------

    There may be instances in which the EPA has not considered, in 
making its BSER determination, a circumstance that makes the BSER 
unreasonable for a particular facility because that circumstance is not 
applicable to the average or typical designated facility in the source 
category. Where the EPA did not consider a circumstance that is 
relevant to a particular designated facility and that circumstance 
causes the BSER to be unreasonable for that facility due to one or more 
of the reasons enumerated in 40 CFR 60.24a(e), a state may find there 
is a fundamental difference from the information the EPA considered in 
determining the degree of emission limitation achievable through 
application of the BSER. That is, if the EPA did not consider any 
information pertaining to a certain circumstance in making its 
determination, facility-specific information relevant to that 
circumstance that demonstrates that achieving the degree of emission 
limitation is unreasonable pursuant to 40 CFR 60.24a(e) may be 
``fundamentally different'' from the information the EPA considered. 
The EPA notes that, in many cases, facility-specific circumstances can 
be considered in terms of differences in cost. For example, an issue of 
the technical feasibility of implementing a control to achieve a 
certain degree of emission limitation may, at its root, be an issue of 
being able to achieve that degree of emission limitation at a 
reasonable cost. Because cost is generally a more quantifiable and 
replicable metric, where possible the EPA expects states to include the 
impacts of any facility-specific circumstances in the cost calculation, 
rather than evaluating those circumstances under a different factor or 
consideration.
    The EPA is also finalizing its proposed clarifying revisions to 40 
CFR 60.24a(e) with further updates. The existing provision in subpart 
Ba was not clear, unless it was read directly in conjunction with 40 
CFR 60.24a(c), that its specific purpose is application of less 
stringent standards of performance pursuant to consideration of RULOF; 
it did not mention less stringent standards until 40 CFR 
60.24a(e)(3).\104\ The EPA therefore proposed and is finalizing 
revisions so that the provision's purpose is now clearly stated at the 
outset. The EPA is also making two further revisions relative to the 
proposed 40 CFR 60.24a(e). First, it is adding back in language 
allowing the RULOF provision to be used to provide a compliance 
schedule longer than otherwise required by an applicable emission 
guideline. In proposing to revise 40 CFR 60.24a(e), the EPA 
inadvertently deleted the phrase ``that make application of a less 
stringent . . . final compliance time significantly more reasonable'' 
in the document containing redline/strikeout of the subpart Ba 
regulations.\105\ It was not the EPA's intent to preclude the use of 
RULOF to provide a longer compliance schedule; this has been part of 
the provision since the original variance in 1975.\106\ However, as the 
language pertinent to providing a longer compliance time no longer fits 
in its original sub-paragraph, the EPA is adding this allowance back 
elsewhere in 40 CFR 60.24a(e).
---------------------------------------------------------------------------

    \104\ 84 FR 32520, 32577 (July 8, 2019).
    \105\ Memorandum, ``Redline/Strikeout for proposed amendments to 
40 CFR 60 Subpart Ba: Adoption and Submittal of State Plans for 
Designated Facilities,'' Docket ID No, EPA-HQ-OAR-2021-0527-0035.
    \106\ See 40 CFR 60.24(f).
---------------------------------------------------------------------------

    Second, the EPA is revising this provision relative to proposal to 
change the circumstances under which invoking RULOF is appropriate from 
the state demonstrating that ``the facility cannot reasonably apply the 
best system of emission reduction to achieve the degree of emission 
limitation determined by the EPA . . .'' to the state demonstrating 
that ``the facility cannot reasonably achieve the degree of emission 
limitation determined by the EPA. . . .'' At proposal, the EPA 
explained that ``the state must show that implementing the BSER is not 
reasonable for the designated facility due to fundamental differences 
between the factors the EPA considered in determining the BSER, such as 
cost and technical feasibility of control and circumstances at the 
designated facility.'' \107\ However, it is not sufficient that a 
facility not be able to implement the BSER; the state must demonstrate 
that the facility cannot otherwise reasonably achieve the EPA's degree 
of emission limitation (for example, through a different system of 
emission reduction) in order for a facility to be eligible for a less 
stringent standard of performance. This is consistent with the 
definition of ``standard of performance'' in CAA section 111(a)(1), 
which is a ``standard for emissions of air pollutants'' that ``reflects 
the degree of emission limitation achievable through application of the 
[BSER],'' as opposed to a standard requiring the application of the 
BSER. That is, the statute requires a certain degree of emission 
limitation, not the use of a particular technology. Therefore, the fact 
that a facility cannot apply the BSER on its own is not sufficient to 
invoke RULOF.
---------------------------------------------------------------------------

    \107\ 87 FR 79199.
---------------------------------------------------------------------------

    The EPA believes that simplifying the language in 40 CFR 60.24a(e) 
will reduce confusion about the ultimate circumstances under which 
invoking RULOF is appropriate: where a particular facility cannot meet 
the degree of emission limitation determined by the EPA. Because the 
degree of emission limitation is based on the EPA's BSER determination, 
the information the EPA considered in determining the BSER remains the 
touchstone for determining when a particular facility cannot reasonably 
achieve the degree of emission limitation in the applicable emission 
guideline. Furthermore, given that the BSER presumptively reflects a 
system that is adequately demonstrated and reasonable for all 
designated facilities within a source category or subcategory, the EPA 
anticipates that in many if not most instances a state considering 
RULOF will in fact be evaluating the reasonableness of applying the 
BSER to achieve the degree of emission limitation. However, even if the 
state is evaluating the use of a different system to achieve the degree 
of emission limitation determined by the EPA, the factors and 
information the EPA considered in the EG, e.g., cost effectiveness, 
will remain relevant to this inquiry.
    As a corollary to this change, the EPA is not finalizing the 
provision proposed at 40 CFR 60.24a(g), which would have provided that 
a state could not apply a less stringent standard of performance where 
a facility could reasonably

[[Page 80517]]

implement a system of emission reduction other than the BSER to achieve 
the degree of emission reduction determined by the EPA. This provision 
is redundant now that the EPA is clarifying in 40 CFR 60.24a(e) that 
states may apply less stringent standards of performance only when they 
demonstrate that a facility cannot reasonably achieve the degree of 
emission limitation determined by the EPA.
    Both subpart B at 40 CFR 60.24(f) and the existing regulations of 
subpart Ba at 40 CFR 60.24a(e) provide that use of RULOF is appropriate 
if a state demonstrates that one of the three circumstances is met 
``with respect to each facility (or class of such facilities).'' In the 
notice of proposed rulemaking for this action, the EPA stated that, 
``[t]o the extent that a state seeks to apply RULOF to a class of 
facilities that the state can demonstrate are similarly situated in all 
meaningful ways, the EPA proposes to permit the state to conduct an 
aggregate analysis of [the five BSER factors] for the entire class.'' 
\108\ The EPA is reiterating in this final rule that invoking RULOF and 
providing a less-stringent standard or performance or longer compliance 
schedule for a class of facilities is only appropriate where all the 
facilities in that class are similarly situated in all meaningful ways. 
That is, they must not only share the circumstance that is the basis 
for invoking RULOF, they must also share all other characteristics that 
are relevant to determining whether they can reasonably achieve the 
degree of emission limitation determined by the EPA in the applicable 
EG. For example, it would not be reasonable to create a class of 
facilities for the purpose of RULOF on the basis that the facilities do 
not have space to install the EPA's BSER control technology if some of 
them are able to install a different control technology to achieve the 
degree of emission limitation in the EG. Similarly, it would not be 
appropriate for a state to conduct a single evaluation pursuant to 40 
CFR 60.24a(f) to apply the same less stringent standard of performance 
to a class of facilities if individual facilities within that class 
have different characteristics that could result in different standards 
of performance. The evaluation of when it is appropriate to create a 
class of facilities is extremely source-sector and EG-specific; the EPA 
will address circumstances in which it may or may not be permissible to 
group facilities for purposes of RULOF in individual EGs.
---------------------------------------------------------------------------

    \108\ 87 FR 79200 n.46.
---------------------------------------------------------------------------

    In summary, the EPA is finalizing its proposed revisions to 40 CFR 
60.24a(e) with additional clarifications. The first is to reflect that 
the ``fundamentally different'' standard applies to all three 
circumstances for invoking RULOF. This clarification reinforces that 
invocation of RULOF is appropriate when the circumstances of a 
particular designated facility are fundamentally different from those 
the EPA considered such that the facility cannot reasonably achieve the 
degree of emission limitation the EPA determined pursuant to CAA 
section 111(a)(1). Second, the EPA is revising the circumstances under 
which invoking RULOF is appropriate from a demonstration that a 
facility cannot reasonably apply the BSER to achieve the degree of 
emission limitation determined by the EPA to a demonstration that the 
facility cannot reasonably achieve the degree of emission limitation 
determined by the EPA. This change is intended to simplify and clarify 
the provision as it is the degree of emission limitation determined by 
the EPA, not the system used to achieve it, that has always been the 
relevant consideration under CAA sections 111(d) and 111(a)(1). Third, 
the EPA is clarifying the provision that states may use RULOF to 
provide for a longer compliance timeline as well as less-stringent 
standards of performance, which was inadvertently omitted from the 
proposed regulatory text. In general, the EPA is revising 40 CFR 
60.24a(e) to provide more objective and consistent criteria for when it 
is appropriate to invoke RULOF in order to guide states in applying 
standards of performance to particular designated facilities and the 
EPA in evaluating state plans. The EPA is not finalizing proposed 40 
CFR 60.24a(g), as this provision is now superfluous given the updates 
to 40 CFR 60.24a(e).
    The EPA acknowledges that what is considered reasonable in light of 
the statutory factors is a fact-specific inquiry based on the source 
category and pollutant that is being regulated pursuant to a particular 
EG, and that the EPA cannot anticipate and address all circumstances 
that may arise in these general implementing regulations. Thus, the EPA 
may consider additional factors and establish additional parameters 
governing the consideration of RULOF, including what deviations from 
the EPA's determinations may be within the range of reasonable versus 
deviations that constitute fundamental differences between facility-
specific circumstances and the EPA's degree of emission limitation 
determination, in a particular EG.
b. Calculation of a Standard Which Accounts for Remaining Useful Life 
and Other Factors
    If a state has demonstrated, pursuant to 40 CFR 60.24a(e), that 
there is a fundamental difference between the information the EPA 
considered in the applicable EG and the information specific to a 
particular source that makes it unreasonable for that source to achieve 
the degree of emission limitation, the state may then apply a less 
stringent standard of performance.\109\ The current RULOF provision, 40 
CFR 60.24a(e), does not specify how a less stringent standard is to be 
calculated and applied. While this provision stands on its own and 
permits states to consider RULOF to apply a less stringent standard of 
performance, the lack of a process for determining any such standards 
makes it difficult for states to know whether the result will be 
approvable and additionally makes it difficult for the EPA to review 
less stringent standards in a consistent and equitable manner. In order 
to provide clarity and ensure the integrity of the emission reduction 
purpose of CAA section 111(d), as well as to ensure the equitable 
treatment of designated facilities across states, the EPA is 
promulgating a framework in 40 CFR 60.24a(f) for the calculation of a 
standard of performance that accounts for RULOF. As explained in this 
section of the preamble, the process the EPA is finalizing differs from 
the proposed framework, but the material components of calculating and 
applying a less stringent standard of performance, and the underlying 
purpose and direction of the EPA's framework, remain the same.
---------------------------------------------------------------------------

    \109\ States intending to apply a less-stringent standard of 
performance pursuant to RULOF would include all information, 
demonstrations, etc. necessary to satisfy 40 CFR 60.24a(e) through 
(h) in their state plan submissions. The EPA will first review a 
state's demonstration that invocation of RULOF pursuant to 40 CFR 
60.24a(e) is appropriate for a particular designated facility 
against the applicable requirements. If the EPA finds that 
demonstration satisfactory, it will proceed to evaluate the standard 
of performance for that facility applied pursuant to 40 CFR 
60.24a(f).
---------------------------------------------------------------------------

    The EPA proposed to require that states determine a source-specific 
BSER for each designated facility for which RULOF has been invoked 
pursuant to 40 CFR 60.24a(e) and include a standard of performance that 
reflects the degree of emission limitation achievable through 
application of that BSER in their state plans. The notice of proposed 
rulemaking explained that the statute requires the EPA to determine the 
BSER by considering emission control methods that it finds to be 
adequately demonstrated, and then determining which is the best system 
of emission

[[Page 80518]]

reduction by evaluating (1) the cost of achieving such reduction, (2) 
nonair quality health and environmental impacts, (3) energy 
requirements, and (4) the amount of reductions.\110\ To be consistent 
with this statutory construct, the EPA proposed to require that in 
determining a source specific BSER for a designated facility (or class 
of such facilities \111\), a state must also consider all these factors 
in applying RULOF for that source.
---------------------------------------------------------------------------

    \110\ The D.C. Circuit has stated that in determining the 
``best'' system, the EPA must take into account ``the amount of air 
pollution'' reduced, see Sierra Club v. Costle, 657 F.2d 298, 326 
(D.C. Cir. 1981), and the role of ``technological innovation.'' Id. 
at 347.
    \111\ See section III.E.3.a. of this preamble. The EPA expects 
to address the appropriateness of invoking RULOF and applying less-
stringent standards to a class of facilities in individual EGs.
---------------------------------------------------------------------------

    Specifically, the EPA proposed that a state in its plan submission 
would identify all control technologies available for the source and 
evaluate the BSER factors for each technology, using the same factors 
and evaluation metrics as the EPA did in developing the EG. For 
example, if the EPA evaluated the cost factor using the evaluation 
metric of capital costs in determining the BSER, the EPA proposed that 
the state must do the same in evaluating a control technology for an 
individual designated facility, rather than selecting a different 
evaluation metric for cost. The state would then calculate the emission 
reductions that applying the source-specific BSER would achieve and 
select the standard of performance which reflects this degree of 
emission limitation. This standard would be in the form or forms (e.g., 
numerical rate-based emission standard) as required by the specific EG.
    While the EPA proposed to require that states identify all control 
technologies or other systems of emission reduction available for the 
source and evaluate each system using the same factors and evaluation 
metrics as the EPA did in determining the BSER, it also solicited 
comment on whether there are additional factors, not already accounted 
for in the BSER analysis, that the EPA should permit states to consider 
in determining a less stringent standard of performance. The EPA 
further solicited comment on whether it should provide that the manner 
in which the EPA conducted the BSER analysis would be a presumptively 
approvable framework for applying a less-stringent standard rather than 
requirements and, if so, what different approaches states might use to 
evaluate and identify less stringent standards of performance.
    The EPA also noted at proposal that CAA section 111(d) requires 
that state plans include measures that provide for the implementation 
and enforcement of a standard of performance. This requirement applies 
to any standard of performance established by a state, including one 
that accounts for RULOF. Such measures include monitoring, reporting, 
and recordkeeping requirements, as required by 40 CFR 60.25a, as well 
as any additional measures specified under an applicable EG. In 
particular, any standard of performance that accounts for RULOF is also 
subject to the requirement under subpart Ba that the state plan 
submission include a demonstration that each standard is quantifiable, 
non-duplicative, permanent, verifiable, and enforceable. 40 CFR 
60.27a(g)(3)(vi). The EPA did not reopen these existing requirements of 
subpart Ba in this rulemaking.
    The EPA received both comments in support of and comments opposed 
to the proposed requirements for calculating facility-specific 
standards of performance under RULOF. Some commenters supported the 
addition of a regulatory framework for facility-specific BSER analysis 
and stated that the BSER factors encompass all relevant information to 
a state's determination of an appropriate standard for a facility. 
Other commenters opposed the proposed framework. Comments in opposition 
largely fell into two categories: Some commenters asserted there is no 
basis in the statute for requiring states to conduct facility-specific 
BSER analyses pursuant to RULOF and, relatedly, that the EPA should not 
put restrictions on what states may consider in applying a less 
stringent standard of performance for a particular source but should 
rather maintain the wide latitude afforded to states under CAA section 
111. Others stated that the EPA's proposed requirements would 
constitute a heavy lift for state agencies and would require 
substantial work for states to implement. In this vein, one commenter 
requested that the EPA not require states to evaluate, as part of their 
facility-specific BSER analyses, control technologies that the Agency 
has previously excluded from the BSER on the basis of technological or 
economic feasibility. Rather, the only control technologies that states 
should be required to evaluate are technologies that result in less 
emission reduction than the technology the EPA determined to be the 
BSER.
    As explained below, the EPA disagrees with comments that there is 
no basis for putting a framework in place for states and the Agency to 
use in applying and evaluating less stringent standards of performance. 
The EPA believes that such a framework is well supported by the 
statutory purpose, text, and context of the RULOF provision. In 
particular, after considering the comments, the EPA believes that the 
purpose, text, and context support a requirement that states (or the 
EPA in the case of a Federal plan) calculate and apply a standard of 
performance that varies from the EPA's degree of emission limitation in 
the applicable emission guideline only to the extent necessary to 
address the fundamental difference that is the basis for invoking 
RULOF.
    First, providing a framework for calculating less stringent 
standards of performance is consistent with the text of CAA section 
111(d) and is responsive to Congress's directive in that provision that 
the Agency prescribe regulations establishing a procedure for state 
plans, including regulations that ``permit'' states ``in applying'' a 
standard of performance to a particular source to ``take into 
consideration'' RULOF. The provisions the EPA is promulgating in this 
action set out a procedure--the series of steps and considerations 
states must undertake to apply a less stringent standard of 
performance. As described in section III.E.2. of this preamble, to 
``permit'' something means to allow or give consent for that thing to 
occur. In this case, the EPA is prescribing the procedures that allow 
for states to apply less stringent standards of performance. To 
``apply'' means ``to put to a special use or purpose'' or ``put into 
practical operation,'' \112\ and ``consideration'' means ``the action 
of taking into account.'' \113\ Thus, the state's authorization to 
``apply[]'' a standard of performance to any particular source, 
``tak[ing] into consideration'' RULOF, means the state may 
particularize a standard of performance for a given source by 
accounting for remaining useful life and other factors where there are 
fundamental differences between the information specific to a facility 
and the information the EPA considered in determining the degree of 
emission limitation achievable through application of the BSER. In 
doing so, the state must remain as consistent as possible with that 
degree of emission limitation in light of what the Supreme

[[Page 80519]]

Court has recognized as the EPA's ``primary regulatory role in section 
111(d)'' \114\ and the emission reduction purpose of CAA section 111.
---------------------------------------------------------------------------

    \112\ Oxford English Dictionary, https://www.oed.com/search/advanced/Meanings?textTermText0=apply&textTermOpt0=WordPhrase, last 
accessed Nov. 1, 2023.
    \113\ Id., https://www.oed.com/search/advanced/Meanings?textTermText0=consideration&textTermOpt0=WordPhrase, last 
accessed Nov. 1, 2023.
    \114\ West Virginia v. EPA, 142 S. Ct. at 2601.
---------------------------------------------------------------------------

    Second, the history and context of CAA section 111(d) supports the 
EPA's authority to provide a framework for states' consideration of 
RULOF. As explained in section III.E.2. of this preamble, the standards 
of performance that states establish in state plans must generally be 
no less stringent than the degree of emission limitation that Congress 
required, which is the degree of emission limitation that EPA 
determines in the applicable EG.\115\ However, in the original 1975 
subpart B implementing regulations, the EPA allowed states to grant 
variances from this degree of emission limitation in cases of economic 
hardship based on the age of the plant and other factors, as long as 
the states could justify the variances.\116\ Congress then, in the 1977 
CAA Amendments, included the RULOF provision in CAA section 111(d)(1), 
which similarly allows states to deviate from the EPA's degree of 
emission limitation based on consideration of an existing source's age 
(i.e., remaining useful life) and other factors.
---------------------------------------------------------------------------

    \115\ 40 CFR 60.24(c); 40 CFR 60.24a(c); see 39 FR 36102.
    \116\ 40 CFR 60.24(f); 40 FR 53344.
---------------------------------------------------------------------------

    Congress's inclusion of the RULOF provision in CAA section 
111(d)(1) should be interpreted as expressing its intent to confirm 
that the EPA has authority to promulgate a regulatory variance 
provision, including the provision the EPA had, at that time, recently 
promulgated. The EPA, following its 1974 proposal of the subpart B 
implementing regulations, had received a comment arguing that it did 
not have authority to promulgate such a variance provision, to which it 
responded by asserting that it did have the authority and explaining 
that such a provision is consistent with CAA section 111(d).\117\ The 
Courts have held that Congress is presumed to be aware of an 
administrative interpretation under certain circumstances.\118\ 
Accordingly, Congress's adoption of the RULOF provision in the 1977 CAA 
Amendments should be interpreted as expressing its intent to make 
explicit under CAA section 111(d) the EPA's authority to promulgate 
regulations that include a variance provision.\119\
---------------------------------------------------------------------------

    \117\ 40 FR 53344.
    \118\ See Lorillard v. Pons, 434 U.S. 575, 580 (1978) 
(``Congress is presumed to be aware of an administrative or judicial 
interpretation of a statute and to adopt that interpretation when in 
re-enacts a statute without change.'').
    \119\ In the notice of proposed rulemaking for this rule, the 
EPA stated that ``[t]here are noticeable differences between the 
subpart B variance provision and the CAA section 111(d) RULOF 
provision that indicate Congress did not intend to incorporate and 
ratify all aspects of the EPA's regulatory approach when amending 
CAA section 111(d) in 1977.'' The EPA thus proposed to conclude that 
it could not ``clearly ascertain whether the statutory RULOF 
provision ratified the variance provision under subpart B . . . .'' 
87 FR 79176, 79205 (Dec. 23, 2022). Upon further consideration, 
however, the EPA believes the most reasonable interpretation of the 
statutory RULOF provision, given its history and context, is that 
Congress intended it to authorize the EPA to provide variances from 
the required degree of emission limitation on a case-by-case basis. 
However, the EPA agrees with its assessment at proposal that 
Congress did not necessarily incorporate or ratify specific aspects 
of the Agency's 1975 variance provision; it is reasonable that 
Congress would not have codified the precise regulations that the 
EPA promulgated in 1975 and instead leave the Agency space to revise 
those regulations as needed, as it is did in 2019 and is doing in 
the present rule.
---------------------------------------------------------------------------

    It is also clear that the EPA understood the RULOF provision in CAA 
section 111(d)(1) to be a variance in the same way it had provided a 
variance in subpart B. This is evidenced by the fact that following the 
1977 CAA Amendments the EPA did not revise its 1975 regulations, which 
were premised on this understanding, for over forty more years.\120\ 
This indicates that the EPA viewed its 1975 regulations granting a 
variance as authorized under the RULOF provision enacted in 1977.
---------------------------------------------------------------------------

    \120\ The ACE rule, in which the EPA promulgated subpart Ba in 
2019, declined to refer to the RULOF provision as a ``variance,'' 
apparently because the term conflicted with that rule's view that 
RULOF would be used to establish standards of performance as a 
general matter. 84 FR 32520,32570 n. 291 (July 8, 2019). The ACE 
rule misunderstood the RULOF provision. As explained throughout 
section III.E. of this preamble, this provision authorizes a state 
to depart from the degree of emission limitation the EPA determines 
under CAA section 111(a)(1) when applying a standard of performance 
to a particular source pursuant to consideration of RULOF. As the 
1975 regulations indicated, 40 FR 53332, 53344 (Nov. 17, 1975), it 
is appropriate to call this type of departure or exception a 
``variance.''
    \121\ The EPA explains the reasons it believes it is now 
necessary to provide the second part of the process for this 
variance--how to calculate a less stringent standard of 
performance--in section III.E.2. of this preamble.
---------------------------------------------------------------------------

    The regulations the EPA is promulgating at 40 CFR 60.24a(f) are 
consistent with the long-held view that the Agency's implementing 
regulations provide a variance. While 40 CFR 60.24a(e) provides the 
process for invoking this variance, to date the regulations have not 
included the second part: how to address a source that has qualified 
for the variance.\121\ Although variances may operate in different ways 
in the context of different statutory and regulatory schemes, it is 
clear from both the language and the context of the RULOF provision 
that Congress intended it to provide for alternative compliance with 
CAA section 111(d), i.e., a less stringent standard of performance, to 
the extent necessary to address the fundamental differences between the 
EPA's EG and the circumstances of a particular facility. Such variances 
are common throughout environmental statutes and, for the environmental 
protection aim to be achieved, must be crafted so that the alternative 
is as close as possible to the statutory standard, even as it departs 
from the generally applicable requirement.
    For example, Clean Water Act (CWA) section 301(b)(2) requires, in 
part, certain sources to achieve effluent limitations consistent with 
application of the best available technology economically achievable, 
which will result in reasonable further progress toward eliminating the 
discharge of all pollutants. These limitations must be determined in 
accordance with factors specified in the statute and are provided by 
either effluent limitation guidelines issued by the EPA or the 
permitting authority on a best professional judgment basis where no 
such national effluent limitation guidelines exist. CWA section 301(n) 
authorizes the EPA to grant variances for existing sources from the 
best available technology requirements of its effluent limitation 
guidelines where a facility can demonstrate that it is fundamentally 
different with respect to the factors (other than cost) specified in 
the statute and considered by the EPA in establishing those 
requirements. CWA section 301(n) further requires that, where a 
variance is warranted, the EPA must provide an alternative requirement 
that (1) is no less stringent than justified by the fundamental 
difference, and (2) will not result in a non-water quality 
environmental impact which is markedly more adverse than the impact 
considered in establishing the rule.\122\
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    \122\ As another example, CWA section 301(c) provides that the 
EPA may modify the best available technology requirements for 
particular sources if a facility can demonstrate that a modified 
standard will (1) represent the maximum use of technology within the 
economic capability of the owner or operator and (2) will result in 
reasonable further progress toward the elimination of the discharge 
pollutants.
---------------------------------------------------------------------------

    Similarly, section 3004(m)(1) of the Resource Conservation and 
Recovery Act (RCRA) requires the EPA to promulgate regulations 
specifying the levels or methods of treatment of hazardous waste, if 
any, that ``substantially diminish the toxicity of the waste or 
substantially reduce the

[[Page 80520]]

likelihood of migration of hazardous constituents from the waste so 
that short-term and long-term threats to human health and the 
environment are minimized.'' The EPA has set generally applicable 
regulatory standards for the treatment of hazardous waste under RCRA 
section 3004(m)(1). The Agency has also has provided regulatorily for 
waste-specific variances in instances in which it is not physically 
possible, or it is inappropriate, to treat waste to the level specified 
in the Agency's treatment standard or to treat waste using the method 
the Agency specified as the treatment standard.\123\ In order for the 
EPA to grant a variance, the party requesting it must provide an 
alternative waste treatment requirement that is sufficient to minimize 
threats to human health and the environment posed by disposal of the 
waste, i.e., that is sufficient to satisfy the underlying statutory 
requirement, even though it differs from the generally applicable 
treatment standard prescribed by the EPA.
---------------------------------------------------------------------------

    \123\ 40 CFR 268.44.
---------------------------------------------------------------------------

    The discussion above highlights examples of environmental statutes 
that require adherence to a generally applicable standard, but under 
which either Congress or the EPA has authorized variances when it is 
impossible or unreasonable for a particular regulated entity to achieve 
that standard. For a general statutory standard requiring the ``best'' 
technology or ``substantial'' progress, the variances are an 
alternative way of achieving the statutory standard, as opposed to an 
exemption from that standard. In the case of the CWA variances, in 
particular, this means that the alternative requirement pursuant to the 
variance constitutes a degree of pollutant limitation that deviates as 
little as possible from the EPA's regulation pursuant to that statutory 
standard. That is, the alternative requirement constitutes a particular 
regulated entity's best effort to achieve the generally applicable 
standard.
    The EPA has crafted 40 CFR 60.24a(e) and (f) to be a variance in 
the same vein as the CWA and RCRA statutory and regulatory provisions 
discussed above. It is clear from both the history and plain language 
of CAA section 111(d)(1) that Congress did not provide an exemption 
from regulation, but rather a method for providing alternative 
compliance with the general statutory requirement of that section.\124\ 
CAA section 111(d) provides that states must submit plans that include 
``standards of performance,'' and CAA section 111(a)(1) defines 
``standard of performance'' as ``a standard for emissions of air 
pollutants which reflects the degree of emission limitation achievable 
through the application of the best system of emission reduction which 
. . . the Administrator determines has been adequately demonstrated.'' 
Thus, the underlying statutory standard is the degree of emission 
limitation determined by the EPA in the applicable EG. A variance from 
this statutory standard is not available if a source can reasonably 
achieve the EPA's degree of emission limitation. If a variance is 
warranted, the alternative requirement, i.e., a standard of performance 
pursuant to consideration of RULOF, must be a standard for emissions of 
air pollutants that is no less stringent than necessary to address the 
fundamental differences identified under 40 CFR 60.24a(e). That is, the 
degree of emission limitation of a standard of performance pursuant to 
RULOF must deviate as little as possible from the degree of emission 
limitation in the applicable EG.\125\ Consistent with the structure of 
CAA section 111(d) generally, the RULOF provision does not prescribe 
the use of any particular system of emission reduction in conjunction 
with a less stringent standard of performance but instead focuses on 
ensuring that the degree of emission limitation deviates no more than 
necessary; anything less would be inconsistent with the general 
statutory framework.
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    \124\ See CAA section 111(d)(1) (requiring that states 
considering RULOF for a particular source nonetheless apply a 
standard of performance to that source); 39 FR 36102, 36102 (Oct. 7, 
1974) (proposed regulations ``provide that States may establish less 
stringent emission standards on a case-by-case basis provided that 
sufficient justification is demonstrated in each case'').
    \125\ Cf. Weyerhauser Co. v. Costle, F.2d 1011, 1035 (D.C. Cir. 
1978) (Clean Water Act variance provision ``authorizes the Agency to 
relieve a particular point source operator from any demands that the 
Act does not allow the Agency to make of the industry generally.'' 
However, the point source operator must still, consistent with the 
general statutory requirement for the industry, use the best 
available technology economically available and ``the variance may 
not halt progress toward eliminating pollution.'').
---------------------------------------------------------------------------

    Thus, 40 CFR 60.24a(f)(1) requires that a less stringent standard 
of performance be no less stringent (or have a compliance schedule no 
longer) than necessary to address the fundamental differences 
identified under 40 CFR 60.24a(e). It also contains a framework that 
states must use, to the extent necessary to satisfy that criterion, to 
determine the less stringent standard of performance. In some 
instances, determining the standard of performance that is no less 
stringent than necessary to address the fundamental differences will be 
straightforward and the state will not need to undertake the analysis 
of additional systems of emission reduction that is laid out in the 
second and third sentences of 40 CFR 60.24a(f)(1). For example, where 
the BSER the EPA has identified in the applicable EG may be implemented 
at the source at either a lower stringency or with a longer compliance 
schedule and it is clear that no other system of emission reduction 
will result in greater stringency or a shorter schedule, it is 
unnecessary for a state to evaluate other systems in order to satisfy 
the first sentence of paragraph (f)(1). In this case, the state would 
simply justify the degree of emission limitation or compliance schedule 
as the most stringent or shortest reasonably possible.
    However, where a particular source cannot implement the types of 
controls that comprise the BSER or where it is not apparent that 
implementation of the BSER at lower stringency or with a longer 
compliance schedule will result in a standard of performance that is no 
less stringent than necessary, evaluation of additional systems of 
emission reduction will be necessary under 40 CFR 60.24a(f)(1). In this 
situation, the EPA does not believe it is reasonably possible to 
determine a standard of performance that satisfies the criterion of 
Sec.  60.24a(f)(1) without considering the systems of emission 
reduction that the EPA determined, in the applicable EG, have been 
adequately demonstrated.\126\ As discussed below, however, it may not 
be necessary for a state to evaluate every system of emission reduction 
that the EPA considered. Thus, the EPA is requiring that, to the extent 
necessary to determine a standard of performance that is no less 
stringent than necessary, states must evaluate the systems of emission 
reduction in the applicable EG. As further discussed below, the EPA 
expects states will leverage the information and analysis the Agency 
has provided in that EG for their evaluations, particularizing that 
information to the circumstances of the particular facility as needed.
---------------------------------------------------------------------------

    \126\ See 40 CFR 60.22a(b)(2).
---------------------------------------------------------------------------

    Similarly, it is not reasonably possible to craft a standard of 
performance that is no less stringent than necessary to address a 
fundamental difference between a particular facility's circumstances 
and the information the EPA considered in determining the degree of 
emission limitation without engaging with that information.\127\ In

[[Page 80521]]

determining the degree of emission limitation in an EG, the EPA 
considers whether available systems of emission reduction have been 
adequately demonstrated, the amount of emissions they reduce, the cost 
of achieving such reduction, any nonair quality health and 
environmental impacts, and energy requirements.\128\ To evaluate 
whether a state's less stringent standard of performance is no less 
stringent than necessary, both states and the EPA need to be able to 
compare the information relevant to the source category (or 
subcategory) with the facility-specific information. Additionally, to 
ensure equitable consideration and treatment of sources in different 
states that have invoked RULOF to apply less stringent standards of 
performance, it is necessary that each state is using a common set of 
factors and metrics as the bases for their decisions. Using the factors 
\129\ and evaluation metrics \130\ that the EPA considered in 
determining the degree of emission limitation ensures ``apples-to-
apples'' comparisons, both between the EPA's degree of emission 
limitation and a state's less stringent standard of performance and 
between different sources in different states. Thus, to the extent that 
states are evaluating systems of emission reduction to determine a less 
stringent standard of performance under 40 CFR 60.24a(f)(1), they must 
use the same factors the EPA considered, and the evaluation metrics the 
EPA used to consider the factors, in doing so.
---------------------------------------------------------------------------

    \127\ Cf. Weyerhauser Co. v. Costle, F.2d 1011, 1035 (D.C. Cir. 
1978) (CWA section 304(b)(2)(B) lays out the minimum factors the EPA 
must consider in determining the best available technology 
economically achievable on a source-category basis. In deciding 
whether a variance sought by a particular point source owner 
represents the ``maximum use of technology within the economic 
capability of (that) owner, the permit-granting agency, and the EPA 
in supervising that agency, must consider the factors laid out in 
section 304(b)(2)(B).'').
    \128\ The D.C. Circuit has stated that in determining the 
``best'' system of emission reduction, the EPA must also take into 
account the role of ``technological innovation.'' See Sierra Club v. 
Costle, 657 F.2d 298, 347 (D.C. Cir. 1981). However, because 
technological innovation is less likely to be relevant at the scale 
of a single facility than it is on a source-category basis, the EPA 
is not explicitly requiring states to consider it under 40 CFR 
60.24a(f)(1).
    \129\ Under 40 CFR 60.24a(f)(1), as finalized in this action, 
states must evaluate the systems of emission reduction identified in 
the applicable EG. The EPA's EGs include systems of emission 
reduction that have been ``adequately demonstrated.'' There is 
therefore no need for states to revisit the ``adequately 
demonstrated'' consideration. However, ``adequately demonstrated'' 
includes ``technical feasibility'' and the EPA acknowledges that 
systems of emission reduction that are adequately demonstrated for 
the source category may not be technically feasible for a particular 
source. The EPA is thus adding ``technical feasibility'' to the list 
of factors states must consider in determining a less stringent 
standard of performance.
    \130\ An ``evaluation metric'' includes both the form of the 
EPA's consideration of a factor and any threshold or level of 
reasonableness the EPA considered in the applicable EG.
---------------------------------------------------------------------------

    For example, assume the EPA considered cost using the evaluation 
metric dollars per ton of pollutant reduced and concluded that costs of 
up to $500/ton of pollutant reduced are reasonable. A state has invoked 
RULOF for a particular source under 40 CFR 60.24a(e) because, based on 
that source's shortened remaining useful life, the cost, in dollars per 
ton of pollutant reduced, of achieving the degree of emission 
limitation in the applicable EG is fundamentally different from $500/
ton. The state, in determining a less stringent standard of performance 
pursuant to 40 CFR 60.24a(f), must evaluate the systems of emission 
reduction in the EG using the cost evaluation metric dollars per ton of 
pollutant reduced. In doing so, the state would consider the 
reasonableness of the costs of those systems against the benchmark of 
$500/ton.
    The regulations at 40 CFR 60.24a(e) also allow states to invoke 
RULOF based on a fundamental difference unrelated to cost, e.g., 
physical impossibility of implementing control equipment necessary to 
achieve the EPA's degree of emission limitation. In this instance, a 
state may find that a particular facility's footprint is such that 
there are no systems of emission reduction that could be installed at 
the facility to achieve the degree of emission limitation in the 
applicable EG. Under 40 CFR 60.24a(f)(1), the state would evaluate the 
systems of emission reduction in the EG using the factors--technical 
feasibility, amount of emission reductions, cost of achieving such 
reductions, nonair quality health and environmental impacts, and energy 
requirements--and evaluation metrics the EPA considered in order to 
determine the standard of performance that is both physically possible 
for the source to achieve and that is no less stringent than necessary.
    As explained in section III.E.3.a., there may be facility-specific 
circumstances and factors that the EPA did not anticipate and consider 
in the applicable EG that make achieving the EPA's degree of emission 
limitation unreasonable for that facility. Such facility-specific 
information may constitute an ``other factor specific to the facility'' 
under 40 CFR 60.24a(e) and could potentially represent a fundamental 
difference between the information the EPA considered in determining 
the degree of emission limitation and the information specific to a 
facility. Such facility-specific ``other factors'' may also be relevant 
in determining and applying a less stringent standard of performance. 
Thus, pursuant to the process the EPA is finalizing in 40 CFR 
60.24a(f)(1), states may consider ``other factors specific to the 
facility'' that were the basis of the demonstration under paragraph (e) 
in determining and applying a less stringent standard of performance.
    In some instances, the fundamental difference between the 
information the EPA considered in the applicable EG and the information 
specific to a facility will manifest as a difference in whether or how 
an enumerated factor applies to a particular facility. For example, 
parasitic load may be an appropriate evaluation metric for considering 
energy requirements for some systems of emission reduction but not for 
others, or water availability may not have been important to the EPA's 
consideration of nonair quality environmental impacts but may be 
relevant for a source located in a particularly water-scarce region. If 
such information represents a fundamental difference that make the 
EPA's degree of emission limitation determination unreasonable for a 
particular facility pursuant to 40 CFR 60.24a(e), it would be 
reasonable and permissible for a state to consider such information in 
applying a less stringent standard of performance under 40 CFR 
60.24a(f)(1).
    In addition to ``other factors'' that the EPA did not necessarily 
consider, there may be circumstances in which a system of emission 
reduction that the EPA did not consider in the applicable EG or that 
the EPA concluded was not adequately demonstrated because, e.g., it is 
not available on a source-category wide basis, is available, 
technically feasible, and potentially reasonable for a particular 
facility.
    The EPA is therefore providing in 40 CFR 60.24a(f)(1) that states 
may consider, in determining a less stringent standard of performance, 
``other factors specific to a facility'' that were the basis for the 
fundamental difference and invoking RULOF under 40 CFR 60.24a(e), as 
well as systems of emission reduction in addition to those the EPA 
considered in the applicable EG. At the same time, however, the EPA in 
a particular EG makes certain judgments about which systems are 
available and adequately demonstrated, as well as how the factors are 
reasonably considered when evaluating those systems for designated 
facilities within the source category. To ensure that any additional 
considerations do not result in a standard of performance that deviates 
more than necessary from the

[[Page 80522]]

EPA's degree of emission limitation, the state must justify how any 
additional consideration results in a standard of performance that is 
no less stringent than necessary to address the fundamental differences 
identified under paragraph (e).
    In addition to being consistent with statutory and regulatory 
precedent on variances, the procedure the EPA is promulgating in 40 CFR 
60.24a(f)(1) for determining standards of performance that are no less 
stringent than necessary is also consistent with CAA section 111. As 
explained throughout this section of the preamble, CAA section 
111(a)(1) defines a standard of performance as a standard for emissions 
of air pollutants that reflects a certain degree of emission limitation 
and gives the EPA the ``primary regulatory role'' \131\ of determining 
that degree of emission limitation. Congress required that, in doing 
so, the EPA evaluate systems of emission reduction that have been 
adequately demonstrated and determine which is best based on the amount 
of emission reductions, cost of achieving such reduction, nonair 
quality health and environmental impacts, and energy requirements. As 
also explained in this section of the preamble, CAA section 111(d) 
directs the EPA to prescribe regulations that ``permit'' states ``in 
applying'' a standard of performance to a particular source to ``take 
into consideration'' RULOF. The requirements the EPA is promulgating in 
40 CFR 60.24a(f)(1) ``permit'' a state to particularize a standard of 
performance for any given source by accounting for RULOF where there 
are fundamental differences between the information specific to a 
facility and the information the EPA considered in determining the 
degree of emission limitation in the applicable EG. In doing so, the 
state must remain as consistent as possible with that degree of 
emission limitation in light of what the Supreme Court has recognized 
as the EPA's primary regulatory role in CAA section 111(d) and the 
emission reduction purpose of CAA section 111. Because Congress has 
identified the factors noted above as relevant considerations for the 
EPA in determining a standard of performance, the Agency believes it is 
also reasonable to require states to consider these systems, factors, 
and evaluation metrics in the manner that the EPA did in applying 
standards of performance pursuant to 40 CFR 60.24a(f).
---------------------------------------------------------------------------

    \131\ West Virginia v. EPA, 142 S. Ct. at 2601.
---------------------------------------------------------------------------

    Furthermore, the EPA's authority to promulgate 40 CFR 60.24a(f) is 
buttressed by CAA section 111(d)(2). As discussed in sections III.E.1. 
and 2. of this preamble, CAA section 111(d)(2) provides that the EPA 
shall have the same authority as under CAA section 110(c) to prescribe 
a Federal plan where a state fails to submit a satisfactory plan. The 
EPA's long-standing interpretation of this subsection is that it 
provides the Agency authority to substantively review states' standards 
of performance.\132\ The existing regulations of subpart Ba and the 
EPA's emission guidelines provide the substantive criteria for the 
Agency's evaluation of standards of performance generally; \133\ the 
regulations the EPA is promulgating at 40 CFR 60.24a(f) constitute the 
substantive criteria for evaluating standards of performance states 
have applied pursuant to RULOF.
---------------------------------------------------------------------------

    \132\ See 40 FR 53342 (CAA section 111(d)'s references to CAA 
section 110 suggest that Congress intended the Administrator to 
apply some substantive criterion to his review of State plans).
    \133\ See 40 CFR 60.24a(c).
---------------------------------------------------------------------------

    Some commenters on proposed 40 CFR 60.24a(f) dislike the EPA's 
approach to determining what constitutes a ``satisfactory'' less 
stringent standard of performance but offer no alternatives, other than 
states should have complete discretion to apply standards pursuant to 
RULOF. This cannot be correct. If this was the case, the EPA would have 
no choice but to approve plans in which states have applied business-
as-usual standards, or standards that allows designated facilities' 
emissions to increase, even if more stringent standards of performance 
are reasonable for that facility. Such an outcome would be inconsistent 
with the text, context, and purpose of CAA section 111. The EPA 
believes the criteria it is providing for the Agency's substantive 
review of less stringent standards of performance are a reasonable 
approach to fulfilling its statutory obligation under CAA section 
111(d)(2) to substantively review standards of performance in state 
plans.
    Moreover, it is not uncommon for the EPA to promulgate regulatory 
frameworks to guide states in areas in which Congress has granted them 
discretion. For example, under the visibility protection provisions of 
CAA section 169A, Congress directed the EPA to promulgate regulations 
to assure that reasonable progress towards meeting the national goal 
for visibility improvement in mandatory class I Federal areas, as well 
as to assure compliance with the requirements of CAA section 169A. 
Section 169A further provides that states implement the visibility 
protection requirements through state implementation plans, in which 
they must include emission limitations for sources of visibility 
impairing pollutants. The statute provides two types of control 
analyses for states to use in determining the applicable emission 
limitations: reasonable progress and best available retrofit 
technology.\134\ Although Congress directed states to determine the 
best available retrofit technology for their existing sources, the EPA, 
in promulgating its implementing regulations, provided a detailed 
methodology and requirements for doing so in 40 CFR 51.308(e) and 40 
CFR part 51, appendix Y. The EPA has similarly prescribed requirements 
for states to determine the emission reduction measures that are 
necessary to make reasonable progress in 40 CFR 51.308(f).\135\ These 
requirements create procedural and substantive frameworks within which 
states exercise their discretion in order to ensure the outcomes of 
their control analyses are consistent with the statutory requirements 
and purpose. The regulatory framework and associated guidance also 
provide states useful clarity as to how the EPA will fulfill its 
statutory obligation to review and approve or disapprove state plans, 
and how the EPA will promulgate Federal plans.
---------------------------------------------------------------------------

    \134\ CAA section 169A(g)(1) and (2). The statutory factors that 
states must use to determine reasonable progress are ``costs of 
compliance, the time necessary for compliance, and the energy and 
nonair quality environmental impacts of compliance, and the 
remaining useful life of any existing source subject to such 
requirements.'' The statutory factors for best available retrofit 
technology analysis are: ``costs of compliance, the energy and 
nonair quality environmental impacts of compliance, any existing 
pollution control technology in use at the source, the remaining 
useful life of the source, and the degree of improvement in 
visibility which may reasonably be anticipated to result from the 
use of such technology.''
    \135\ The EPA has also issued extensive and detailed guidance 
for states in conducting reasonable progress analyses for sources of 
visibility impairing pollutants. See Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period (2019), 
available at https://www.epa.gov/visibility/guidance-regional-haze-state-implementation-plans-second-implementation-period; 
Clarifications Regarding Regional Haze State Implementation Plans 
for the Second Implementation Period (2021), available at https://www.epa.gov/visibility/clarifications-regarding-regional-haze-state-implementation-plans-second-implementation.
---------------------------------------------------------------------------

    The EPA is not providing that states can forgo analyzing control 
technologies or other systems of emission reduction that the EPA has 
excluded from being the BSER on the basis of technological or economic 
feasibility, as suggested by commenters. The EPA conducts BSER analyses 
on a source-category basis. It may be that a system of emission

[[Page 80523]]

reduction is generally adequately demonstrated but is not the BSER 
because it cannot be applied to designated facilities across the 
category at a reasonable cost or because it is technically infeasible 
for a certain portion of the category. However, designated facilities 
that are eligible to receive a less-stringent standard of performance 
are in demonstrably different circumstances than facilities in the 
source category generally. Therefore, control technologies or other 
systems that may not be the BSER for the source category may be 
reasonable for a source that has invoked RULOF. Similarly, to avoid 
inadvertently precluding consideration of a system that could allow a 
state to apply a standard of performance that is no less stringent than 
necessary, the EPA is not providing that states must consider only 
control technologies or systems that result in less emission reductions 
than the EPA's BSER. While it is true that states should only be in the 
position of applying less stringent standards of performance if they 
have demonstrated that a designated facility cannot achieve the degree 
of emission limitation, there may be situations in which it is not 
practical or feasible to ascertain a priori what degree of emission 
limitation a technology or system could achieve when applied to a 
particular source. Thus, the EPA does not believe it is reasonable to 
narrow the scope of control technologies or other systems of emission 
reduction that states must consider under these general implementing 
regulations. The Agency may find it appropriate to do so in the context 
of an individual EG.
    Some commenters noted the resources and potential burden associated 
with conducting the proposed source-specific BSER analyses. While the 
EPA is not finalizing a requirement for states to conduct source-
specific BSER analyses, it acknowledges that stakeholders could have 
similar concerns in the context of the provision being promulgated at 
40 CFR 60.24a(f). However, the EPA does not believe the RULOF 
provisions will significantly add to states' planning processes. First, 
as explained in section III.E.2. of this preamble, consistent with the 
statutory framework the EPA believes that use of RULOF should be an 
exception to the general rule that the EPA's degree of emission 
limitation is reasonable for designated facilities within the 
applicable source category. Given the EPA's ability to subcategorize 
source categories and to tailor its EG to the circumstances of each 
subcategory, using RULOF to apply a less stringent standard of 
performance should be appropriate in only very limited circumstances.
    Second, as explained above, the EPA is providing in 40 CFR 
60.24a(f)(1) that states must evaluate the systems of emission 
reduction in the applicable EG using the factors and evaluation metrics 
the EPA considered ``[t]o the extent necessary to determine a standard 
of performance'' that is no less stringent than necessary to address 
the fundamental differences identified under paragraph (e). As noted 
above, the EPA anticipates that in some if not many cases, states will 
be able to demonstrate that the less stringent standard of performance 
they are applying is no less stringent than necessary without 
evaluating all of the systems of emission reduction in the applicable 
EG. For example, if the EPA's degree of emission limitation is 95% 
reduction in emissions and a state applies a less stringent standard of 
performance that results in 90% reduction, the state may reasonably 
forgo evaluating additional systems of emission reduction if, based on 
the information in the EG, it is clear that none is able to achieve 
comparable reductions. Similarly, a state may not need to consider 
every system of emission reduction in an applicable EG if it starts by 
evaluating the system or systems that achieve the greatest emission 
reductions and applies a standard of performance corresponding to one 
of those systems.
    Third, the EPA anticipates states applying less stringent standards 
of performance would leverage the information and analyses the Agency 
has provided in the applicable EG. In promulgating an EG, the EPA is 
required to provide the elements listed in 40 CFR 60.22a(b), which 
include ``[a] description of systems of emission reduction which, in 
the judgment of the Administrator, have been adequately demonstrated,'' 
and ``[i]nformation on the degree of emission limitation which is 
achievable with each system, together with information on the costs, 
nonair quality health environmental [sic] effects, and energy 
requirements of applying each system to designated facilities,'' as 
well as ``[s]uch other available information as the Administrator 
determines may contribute to the formulation of State plans.'' In many 
cases, the EPA provides extensive technical support documents including 
feasibility and cost analyses. The Agency also typically discusses the 
types of nonair quality health and environmental effects and energy 
requirements that might be expected in conjunction with various systems 
of emission reduction applicable to the source category. Although 
designated facilities for which RULOF has been invoked are in 
fundamentally different circumstances that the average or typical 
facilities that EPA considers in the context of its own analysis, the 
information provided in an EG will provide a starting point and, in at 
least some cases, much of the analytical basis for states' evaluations.
    Fourth, in the event the state needs to analyze different systems 
of emission reduction to determine a less stringent standard of 
performance, the EPA believes it would be in this position regardless 
of any requirements the Agency does or does not provide. That is, 
because CAA section 111(d)(1) requires a standard of performance for 
each existing source, the EPA does not believe the framework being 
provided in 40 CFR 60.24a(f) will significantly alter states' workload 
if and when invoking RULOF. Rather, it is intended to provide clarity 
for states in developing standards of performance consistent with the 
statutory requirements. The EPA intends for these requirements to in 
fact reduce planning burdens overall, as they provide a framework for 
states to submit approvable standards of performance for sources 
invoking RULOF, thereby obviating the need for subsequent plan 
revisions to address any disapproved standards.
    As noted above, the EPA requested comment on whether to provide 
consideration of the five BSER factors as part of a source-specific 
BSER analysis as a presumptively approvable framework for applying a 
less stringent standard of performance, as opposed to requirements. The 
framework the EPA is finalizing in this action differs from the 
proposed approach under which states would conduct source-specific BSER 
analyses; the process the EPA is finalizing at 40 CFR 60.24a(f) is 
premised on determining the appropriate variance from the EPA's degree 
of emission limitation. The EPA is providing this framework as 
requirements for states applying a less stringent standard of 
performance. As explained elsewhere in this section of the preamble, 
the EPA does not believe it is possible, as a practical matter, to 
determine a standard of performance that is no less stringent than 
necessary without evaluating the systems of emission reduction that the 
EPA determined are adequately demonstrated and engaging with the 
factors and evaluation metrics that the EPA used to evaluate those 
systems in the applicable EG. Therefore, the EPA believes that states 
must use the framework laid out in 40 CFR 60.24a(f) in order for the 
resulting variance to be

[[Page 80524]]

consistent with CAA section 111(d). As laid out in the Sec.  
60.24a(f)(1), states may also consider additional systems and other 
factors specific to the facility that were the basis of the fundamental 
difference identified under 40 CFR 60.24a(e), so long as they justify 
that any such consideration is consistent with applying a standard of 
performance that is no less stringent than necessary.
    In sum, the EPA is not finalizing its proposed requirement under 40 
CFR 60.24a(f)(1) that states that have invoked RULOF for a particular 
facility determine a source-specific BSER. As a result, it is also not 
finalizing the provision proposed at 40 CFR 60.24a(f)(2) that would 
have required states to calculate the emission reductions a source-
specific BSER would achieve and apply the standard of performance that 
reflects this degree of emission reduction. However, consistent with 
its proposal, the EPA continues to believe it is necessary for the 
Agency to provide a process for states that have invoked RULOF for a 
particular facility to follow in applying a less stringent standard of 
performance. The EPA is therefore promulgating requirements at 40 CFR 
60.24a(f) to ensure that states that have invoked RULOF for a 
particular designated facility apply a standard of performance that is 
no less stringent than necessary to address the fundamental differences 
identified under 40 CFR 60.24a(e). These provisions are necessary to 
ensure consistency with the purpose, text, and context of CAA section 
111(d), including an understanding of RULOF as a limited variance from 
the degree of emission limitation in the applicable EG. The provisions 
at 40 CFR 60.24a(f)(1) as finalized will require states to determine a 
less stringent standard of performance that is no less stringent than 
necessary. In doing so, states must, to the extent necessary, evaluate 
the systems of emission reduction in that EPA using the factors and 
evaluation metrics that the EPA considered. States may also consider, 
as justified, other factors specific to the facility that were the 
basis for invoking RULOF under 40 CFR 60.24a(e), as well as additional 
systems of emission reduction. The EPA is finalizing the provision 
proposed at 40 CFR 60.24a(f)(3), requiring that a less stringent 
standard of performance pursuant to RULOF be in the form \136\ required 
by the applicable EG, at paragraph (f)(2).
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    \136\ ``Form'' of the less stringent standard of performance 
refers to a numerical emissions standard versus a work practice 
standard, the units in which a standard is expressed, or both.
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c. Contingency Requirements
    The EPA recognizes that a source's operations may change over time 
in ways that cannot always be anticipated or foreseen by the EPA, 
state, or designated facility. This is particularly true where the 
basis of the application of RULOF is a designated facility's 
operational conditions, such as the source's remaining useful life or 
restricted capacity. If the designated facility subsequently changes 
its operating conditions after the state or EPA applies a less 
stringent standard of performance, the basis for the variance may be 
abrogated and the standard of performance may no longer be no less 
stringent than necessary. For example, a state may seek to invoke RULOF 
for an EGU on the basis that it is running at lower utilization than 
the EPA considered in determining the degree of emission limitation and 
intends to do so for the duration of the compliance period required by 
an EG. Under this scenario, the state may be able to demonstrate that 
it is not reasonably cost-effective for the designated facility to 
achieve the degree of emission limitation and the state could set a 
less stringent standard of performance for this EGU. However, because 
reduced utilization is not a physical constraint on the designated 
facility's operations, it is possible that the source's utilization 
could increase in the future without any other legal constraint.
    The EPA proposed to address this potential scenario by adding a 
contingency requirement to the RULOF provision at 40 CFR 60.24a(h) that 
would require a state to include in its state plan an instrument making 
a source's operating condition, such as remaining useful life or 
restricted capacity, enforceable whenever the state seeks to rely on 
that operating condition as the basis for a less stringent standard. 
This requirement would not extend to instances where a state applies a 
less stringent standard on the basis of an unalterable condition that 
is not within the designated source's control, such as technical 
infeasibility, space limitations, water access, or geologic 
sequestration access. Rather, this requirement addresses operating 
conditions such as operation times, operational frequency, process 
temperature and/or pressure, fuel parameters, and other conditions that 
are subject to the discretion and control of the designated facility.
    Many commenters on this subject supported the EPA's proposed 
approach to operating conditions that are within a designated 
facility's control. They noted that, in the absence of an enforceable 
requirement, a designated facility could change its operations with the 
result being foregone emission reductions and undermining of the level 
of stringency in the EG. One commenter stated that the EPA should not 
permit a source that has legally committed to a retirement date as a 
condition of invoking RULOF to receive a less-stringent standard to 
postpone that date because, even if it committed to meet the emission 
limitation in the EG from that point forward, it could not make up for 
its excess emissions before that time. Other commenters opposed the 
EPA's proposed requirement and asserted that the EPA had cited no legal 
authority or record basis for a need to require states to make 
operational conditions that are the basis of less stringent standards 
into enforceable requirements in state plans. One commenter noted that 
states should have latitude in their regulatory and permit processes to 
determine what additional restrictions or contingencies are necessary 
to ensure that the less stringent standard remains appropriate over 
time.
    The EPA continues to believe the requirement proposed at 40 CFR 
60.24a(h) is a necessary and reasonable safeguard to ensure that 
designated facilities' standards of performance are consistent with the 
level of stringency Congress required. Where are particular facility's 
operating conditions are the basis for a variance from the EPA's degree 
of emission limitation, that variance is warranted only so long as the 
operating condition remains a fundamental difference between that 
facility's circumstances and the information the EPA considered in the 
applicable EG. Therefore, in order for a state plan to include 
satisfactory standards of performance as well as measures for the 
implementation and enforcement of those standards pursuant to CAA 
section 111(d)(1), the contingency must be an enforceable requirement 
in that plan; upon EPA approval of the plan the contingency becomes a 
federally enforceable requirement (in addition to being enforceable 
through the state-law instrument that was included in the plan). 
Inclusion in a state permit, rule, or other instrument alone is not 
sufficient to satisfy CAA section 111(d)(1). A state-only instrument 
can additionally be changed outside the state plan revision process, 
which could result in the lifting of the operational condition without 
a corresponding adjustment to the designated facility's less stringent 
standard of performance.
    The EPA notes that it has a practice of requiring operational 
conditions that

[[Page 80525]]

are the basis of less stringent emission limitations to be included in 
state plans or state implementation plans under CAA section 111 or 110, 
respectively, including in the Affordable Clean Energy Rule \137\ and 
under the CAA's regional haze program.\138\
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    \137\ 84 FR 32520, 32558 (July 8, 2019). The EPA has proposed to 
repeal the ACE Rule on other grounds. See 88 FR 33240 (May 23, 
2023).
    \138\ See, e.g., 76 FR 12651, 12660-63 (March 8, 2011) (best 
available retrofit technology requirements for Oregon source based 
on enforceable retirement that were to be made federally enforceable 
in state implementation plan); Guidance on Regional Haze State 
Implementation Plans for the Second Implementation Period at 34, 
EPA-457/B-19-003, August 2019 (to the extent a state relies on an 
enforceable shutdown date for a reasonable progress determination, 
that measure would need to be included in the SIP and/or be 
federally enforceable).
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    States may revise their state plans to allow a designated facility 
that has committed to retiring as the basis for invoking RULOF to 
postpone its retirement date. There could be many reasons a designated 
facility that previously agreed to a federally enforceable commitment 
to cease operations by a certain date might need to extend that date. 
The EPA is unable to assess, in the context of these general 
implementing regulations, an appropriate approach for all possible 
circumstances to ensure that the level of stringency of the EG is not 
undermined. The EPA anticipates addressing this consideration in 
individual EGs.
    As previously discussed, the state plan submission must also 
include measures for the implementation and enforcement of a standard 
that accounts for RULOF. For standards that are based on operating 
conditions that a facility has discretion over and can control, the 
operating condition and any other measure that provides for the 
implementation and enforcement of the less stringent standard must be 
included in the plan submission and as a component of the standard of 
performance. For example, if a state applies a less stringent standard 
for a designated facility on the basis of a lower capacity factor, the 
plan submission must include an enforceable requirement for the source 
to operate at or below that capacity factor, and include monitoring, 
reporting, and recordkeeping requirements that will allow the state, 
the EPA, and the public to ensure that the source is in fact operating 
at that lower capacity. A specific EG may detail supplemental or 
different requirements on implementing the proposed general requirement 
that a state plan submission include both the operating condition that 
is the basis for a less stringent standard, and measures to provide for 
the implementation and enforcement of such standard.
    The EPA notes there may be circumstances under which a designated 
facility's operating conditions change permanently so that there may be 
a potential violation of the contingency requirements approved as 
federally enforceable components of the state plan. For example, a 
designated facility that was previously running at lower capacity now 
plans to run at a higher capacity full time, which conflicts with the 
federally enforceable state plan requirement that the facility operate 
at the lower capacity. To address this concern, a state may submit a 
plan revision to reflect the change in operating conditions. Such a 
plan revision must include a new standard of performance that accounts 
for the change in operating conditions. The plan revision would need to 
include a standard of performance that reflects the degree of emision 
limitation required by the EG and meet all applicable requirements, or 
if a less stringent standard is still warranted for other reasons, the 
plan revision would need to meet all of the applicable requirements for 
considering RULOF. The new standard of performance would only become 
effective upon the EPA's determination that the plan revision is 
satisfactory.
    The EPA is finalizing as proposed the requirement that, where a 
plan applies a less stringent standard of performance on the basis of 
an operating condition within the designated facility's control, such 
as remaining useful life or restricted capacity, the plan must also 
include such operation condition or conditions as an enforceable 
requirement (this requirement was proposed at 40 CFR 60.24a(h) and is 
being finalized at 40 CFR 60.24a(g)). The plan must also include 
requirements to provide for the implementation and enforcement of the 
operating condition, such as monitoring, reporting, and recordkeeping 
requirements.
d. Requirements Specific to Remaining Useful Life
    CAA section 111(d) explicitly requires that the EPA permit states 
to consider remaining useful life in applying a standard of 
performance. While the EPA may consider the age of designated 
facilities within a source category as a general matter in determining 
the BSER, it is a factor that can have considerable variability from 
facility to facility. The annualized costs can change considerably 
based on the applied technology at any particular designated facility 
given the amortization period. When the EPA determines a BSER, it 
considers cost and, in many instances, specifically considers 
annualized costs associated with payment of the technology associated 
with the BSER. The shorter that payback period is (i.e., shorter 
remaining useful life), the less cost-effective that BSER may become. 
The current RULOF provision in subpart Ba generally allows for a state 
to account for remaining useful life to set a less stringent standard. 
However, the provision does not provide guidance or parameters on when 
and how a state may do so.
    Consistent with the principles described previously in section 
III.E., the EPA proposed requirements for when a state seeks to apply a 
less stringent standard on grounds that a designated facility will 
retire in the near future. Specifically, the EPA proposed that the 
Agency would be required to identify in an EG the outermost retirement 
date for designated facilities that could qualify for consideration of 
remaining useful life, or a methodology and considerations for states 
to use in determining such an outermost date. The proposed regulations 
would have also allowed states to apply a routine maintenance standard 
of performance to designated facilities with ``imminent'' retirement 
dates and additionally provided that the EPA may define the timeframe 
for imminent retirements in an EG. Finally, consistent with the 
proposed provisions regarding contingency requirements, the EPA 
proposed that any state plan that applies a standard of performance 
that is based on a particular designated facility's remaining useful 
life must include the retirement date as an enforceable commitment and 
provide measures for its implementation and enforcement.
    Several commenters supported the EPA's proposal to identify in an 
EG an outermost and imminent retirement date to guide states' 
consideration of remaining useful life in setting less stringent 
standards. Some supportive commenters also urged the EPA to prescribe 
further requirements for designated facilities that rely on a shorter 
remaining useful life, including prohibiting them from extending their 
retirement dates and defining an imminent retirement as one that occurs 
within two years of state plan submission. Other commenters opposed the 
EPA's proposed requirements around the consideration of remaining 
useful life. Some argued that the requirements would foreclose states 
from considering remaining useful life when a designated facility's 
retirement date falls outside the prescribed range and that, although 
states must reasonably exercise their discretion, the

[[Page 80526]]

CAA puts no limits on their consideration of this factor. Adverse 
commenters also noted that the remaining useful life consideration is 
very source-specific and that there may be relevant factors that the 
EPA would not necessarily take into account when determining the 
outermost and imminent dates in an EG.
    After consideration of the comments received, the EPA has decided 
not to finalize the provisions proposed at 40 CFR 60.24a(i) regarding 
remaining useful life. As a general matter, the proposed requirement 
for the EPA to identify an outermost and imminent retirement date for 
the consideration of remaining useful life was intended to assist 
states in developing their state plans and to provide transparency and 
consistency in states' application of, and the EPA's review of, 
standards of performance based on this factor. As explained in the 
preamble to the proposed rule, a designated facility's remaining useful 
life generally impacts a cost analysis by changing the amortization 
period, or the period of time over which a facility pays the capital 
costs for a system of emission reduction. The shorter the period, the 
higher the annualized costs. The EPA generally assumes a certain 
amortization period in its BSER determination based on, e.g., the 
lifespan of the system under consideration and the characteristics of 
facilities within the source category. A designated facility that has a 
shorter remaining useful life than the amortization period the EPA 
assumed in its BSER determination will likely find that achieving the 
degree of emission based on application of the BSER has higher 
annualized costs; the larger the difference between a particular 
facility's remaining useful life and the EPA's assumed amortization 
period, the larger the difference in annualized costs. However, as a 
factual matter, there is a point at which a designated facility's 
remaining useful life is long enough so that the difference in 
annualized costs for that facility and the costs the EPA considered 
reasonable in the applicable EG are not fundamentally different. At 
this point, it would be unreasonable for a state to use remaining 
useful life as the basis for a less-stringent standard for that 
facility because it could achieve the EPA's degree of emission 
limitation at a reasonable cost.
    Similarly, an imminent retirement date could serve to streamline 
states' planning for sources with remaining useful lives that are so 
short that, as a factual matter, no available system of emission 
reduction could have reasonable costs. What constitutes a reasonable 
cost in the context of a specific EG could depend on, inter alia, the 
source category, the emission reductions available, and the designated 
pollutant.
    However, the EPA agrees with commenters that states' consideration 
of remaining useful life and what constitutes reasonable consideration 
of this factor will necessarily depend on the source category, the 
variability of the individual designated facilities within the source 
category, and the structure of the applicable EG. In some instances, 
the nature of the designated facilities and structure of the EG may 
render a designated facility's remaining useful life of little 
relevance. For example, where a BSER is based on operational changes or 
activities that entail little to no capital cost, the remaining useful 
life of a designated facility should not change the reasonableness of 
the system and there would be no need for the EPA to prescribe imminent 
and outermost retirement dates in an EG. Alternatively, designated 
facilities within the source category may, by virtue of how an industry 
developed, fall into discrete age classes based on their remaining 
useful lives such that the EPA considers this characteristic in 
creating subcategories and determining appropriate BSERs for each 
subcategory. In this case, too, there might be little utility in the 
EPA defining imminent and outermost dates for consideration of 
remaining useful life in an EG.
    The EPA is therefore choosing not to finalize the provisions 
proposed at 40 CFR 60.24a(i), although it may be appropriate to include 
outermost and imminent retirement dates for the consideration of 
remaining useful life in individual EGs. The proposed provisions 
included a requirement that any plan that applies a less-stringent 
standard based on remaining useful life must include the retirement 
date for the designated facility as an enforceable commitment, 
including any measures that provide for the implementation and 
enforcement of such a commitment. The EPA notes that although it is not 
finalizing the proposed 40 CFR 60.24a(i)(3), as discussed in section 
III.E.3.c. of this preamble plans that include less-stringent standards 
based on remaining useful life will still be required to include the 
relevant designated facilities' retirement dates as enforceable 
commitments and include any measures necessary to provide for the 
implementation and enforcement of those commitments pursuant to the 
requirement being finalized at 40 CFR 60.24a(g).
    The EPA also reiterates that the obligation to include a standard 
of performance in a state plan applies to any designated facility that 
meets the applicability requirements of an EG as of that EG's 
compliance date. That is, a state plan must include a standard of 
performance for a designated facility that is retiring after the 
compliance date, even if the facility has an enforceable commitment to 
retire imminently following that date. In the case of an imminently 
retiring designated facility, it may be reasonable for a state to apply 
a standard reflecting that facility's business as usual; the EPA will 
address this and other potential considerations, including how such a 
standard would be calculated, in individual EGs.
e. Reasoned Decision Making and the EPA's Review of State Plans 
Invoking RULOF
    As discussed previously in section III.E. of this preamble, under 
CAA section 111(d)(2), the EPA has the obligation to determine whether 
a state plan submission is ``satisfactory.'' This obligation extends to 
all aspects of a state plan, including the application of a less 
stringent standard of performance that accounts for RULOF. States carry 
the primary responsibility to develop plans that meet the requirements 
of CAA section 111(d) and therefore have the obligation to justify any 
consideration of RULOF in applying standards less stringent than the 
degree of emission limitation provided by the EG. That states must 
provide a reasoned basis including, where applicable, technical 
analyses and other documentation to support the decisions they make in 
their plans is fundamental to the structure of CAA section 111(d).\139\ 
As explained in section III.E.3.a. of this preamble, consistent with 
the statutory framework of CAA section 111(d), state plans must ensure 
that designated facilities achieve the degree of emission limitation 
achievable through application of the BSER as determined by the EPA 
unless doing so would be unreasonable for a particular facility. The 
fundamental tenet has been reflected in the EPA's regulations since 
1975.\140\ Thus, a ``satisfactory'' plan is one that, inter alia, 
applies less-stringent standards only where the state has demonstrated 
that achieving the EPA's degree of emission limitation would be 
unreasonable pursuant to 40 CFR 60.24a(e). A demonstration that a 
particular designated facility cannot

[[Page 80527]]

reasonably achieve the degree of emission limitation determined by the 
EPA will, in most cases, necessarily be supported by technical analysis 
that assesses a particular designated facility and compares its 
circumstances to those the EPA considered in its EG.
---------------------------------------------------------------------------

    \139\ See, e.g., 84 FR 32558 (ACE Rule explained that state 
plans must adequately document and demonstrate the process and 
underlying data used to establish standards of performance so that 
EPA can adequately and appropriately review the plan to determine 
whether it is satisfactory).
    \140\ See 40 CFR 60.24(c), 60.24a(c).
---------------------------------------------------------------------------

    While it is within states' discretion to apply a less stringent 
standard of performance where the state has identified fundamental 
differences for a particular facility (or class of facilities), the 
state must support its decision making and demonstrate that it results 
in a standard of performance that is no less stringent than necessary 
to address the fundamental differences and that meet the applicable 
requirements. When a state invokes RULOF and applies a less-stringent 
standard, it must demonstrate that the standard is no less stringent 
than necessary to address the fundamental difference identified by the 
state. Absent such a demonstration, the EPA cannot ascertain that a 
less-stringent standard meets the requirements of CAA section 111; that 
is, it cannot determine that a less-stringent standard is 
``satisfactory.''
    The requirements proposed at 40 CFR 60.24a(j) were intended to 
explicitly clarify states' responsibilities when invoking RULOF and to 
assist them in developing standards in a manner that enables the Agency 
to determine whether such standards are ``satisfactory.'' The proposed 
requirements provided that states would carry the burden of making any 
demonstrations in support of less-stringent standards pursuant to the 
RULOF provisions. States would carry the primary responsibility to 
develop plans that meet the requirements of CAA section 111(d) and 
therefore have the obligation to justify any accounting for RULOF in 
support of standards less stringent than those provided by the EG. 
While the EPA has discretion to supplement a state's demonstration, the 
Agency may also find that a state plan's failure to include a 
sufficient RULOF demonstration is a basis for concluding the plan is 
not ``satisfactory'' and therefore disapprove the plan. The EPA further 
proposed that for the required demonstrations, states must use 
information that is applicable to and appropriate for the specific 
designated facility, and must show how information is applicable and 
appropriate. As RULOF is a source-specific determination, it is 
appropriate to require that the information used to justify a less 
stringent standard for a particular designated facility be applicable 
to and appropriate for that source. Finally, the EPA proposed to 
require that the information used for states' demonstrations under the 
new RULOF provisions must come from reliable and adequately documented 
sources, such as EPA sources and publications, permits, environmental 
consultants, control technology vendors, and inspection reports.
    Comments received on the proposed requirements regarding states' 
burden of demonstration and the use of site-specific information were 
generally supportive while also requesting further clarification of and 
flexibility in the types of information that the EPA would consider 
acceptable. One commenter suggested that the EPA allow states to use 
historical data even if not published or documented by third parties, 
as this constitutes site-specific information, while another suggested 
allowing verified industry information, even if it is not site-
specific.
    Despite the generally supportive commenters received, the EPA is 
not finalizing the requirements proposed at 40 CFR 60.24a(j). While the 
EPA continues to find that states carry the burden of making any 
demonstrations in support of less-stringent standards pursuant to RULOF 
in developing their plans, we have determined that it is not necessary 
to promulgate this expectation as a standalone regulatory requirement. 
States always bear the responsibility of reasonably documenting and 
justifying the standards of performance in their plans.\141\ If the EPA 
cannot ascertain, based on the information and analysis included in a 
state plan submission, whether a standard of performance meets the 
statutory requirements, it cannot find that standard satisfactory. 
Additionally, it is de facto necessary to use information that is 
applicable to and appropriate for the designated facility when 
analyzing systems of emission reduction for that particular facility. 
For example, for a designated facility invoking RULOF based on its 
unique design features, the state plan must provide information 
corroborating the uniqueness of those features and analysis 
demonstrating how they result in the facility being unable to 
reasonably achieve the degree of emission limitation determined by the 
EPA. It would not be reasonable in this instance for a state to use 
generic industry data, whether verified or not, as the basis of 
demonstrations pursuant to 40 CFR 60.24a(e) and (f).
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    \141\ Where a state has relied on information or analyses the 
EPA provided in an applicable EG as part of its source specific BSER 
determination, a state would explain why such reliance is reasonable 
and cite or otherwise incorporate that information or analyses in 
its state plan submission.
---------------------------------------------------------------------------

    While the proposed requirements would have simply codified 
generally applicable tenets of reasoned decision making, the EPA 
recognizes that the specific types and provenances of information 
needed to justify a less-stringent standard can vary significantly 
between not only source categories, but between individual designated 
facilities within a source category. As a result, the proposed 
provisions had the potential to be both over- and underinclusive. While 
we are not finalizing these provisions as generally applicable 
requirements for state plans, they and the accompanying discussion in 
the notice of proposed rulemaking \142\ remain important guidance for 
plan development. The EPA may also choose to promulgate requirements 
for RULOF demonstrations in individual EGs.
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    \142\ See 87 FR 79176, 79202-03 (Dec. 23, 2022).
---------------------------------------------------------------------------

f. Consideration of Impacted Communities
    While the consideration of RULOF can be warranted to apply a less 
stringent standard of performance to a particular facility, such 
standards have the potential to result in disparate health and 
environmental impacts to communities most affected by and vulnerable to 
those impacts from the designated facilities being addressed by the 
state plan. These communities could be put in the position of bearing 
the brunt of the greater health or environmental impacts resulting from 
that source implementing less stringent emission controls than would 
otherwise have been required pursuant to the EG. The EPA considers that 
a lack of attention to such potential outcomes would be antithetical to 
the public health and welfare goals of CAA section 111(d) and the CAA 
generally. Because of CAA section 111(d)(2)'s requirement that the EPA 
determine whether a state plan is ``satisfactory'' applies to such 
plan's consideration of RULOF in applying a standard of performance to 
a particular facility, the EPA must determine whether a plan's 
consideration of RULOF is consistent with CAA section 111(d)'s overall 
health and welfare objectives.
    In order to address the potential exacerbation of health and 
environmental impacts to these communities as a result of applying a 
less stringent standard, the EPA proposed to require states to consider 
such impacts when applying the RULOF provision to establish those 
standards. Under the proposed provisions at 40 CFR 60.24a(k), to the 
extent a designated facility would qualify for a less stringent 
standard through

[[Page 80528]]

consideration of RULOF, the state, in calculating such standard, would 
have been required to demonstrate consideration of the potential health 
and environmental impacts and potential benefits of control to 
communities most affected by and vulnerable to the impacts from the 
designated facility considered in a state plan for RULOF provisions. 
These communities will be identified by the state as pertinent 
stakeholders under the finalized meaningful engagement completeness 
requirements described in section III.C. of this preamble.
    The notice of proposed rulemaking further explained that state plan 
submissions seeking to invoke RULOF for a source would be required to 
identify where and how a less stringent standard impacts these 
communities. In evaluating a RULOF option for a facility, states should 
describe the health and environmental impacts anticipated from the 
application of RULOF for such communities, along with any feedback the 
state received during meaningful engagement regarding its draft state 
plan submission, including on any standards of performance that 
consider RULOF. Additionally, to the extent there is a range of options 
for reasonably controlling a source based on RULOF, the EPA proposed 
that in determining the appropriate standard of performance, states 
should consider the health and environmental impacts to the communities 
most affected by and vulnerable to the impacts from the designated 
facility considered in a state plan for RULOF provisions and provide in 
the state plan submission a summary of the results that depicts 
potential impacts for those communities for that range of reasonable 
control options.
    The EPA received a wide range of comments on the proposed 
requirements for state plans to consider the potential pollution 
impacts and benefits of control to communities most affected by and 
vulnerable to emissions from a designated facility that is invoking 
RULOF. Several commenters supported the proposal and agreed that, given 
that the purpose of regulating stationary source pollution under CAA 
section 111 is to address emissions that endanger public health and 
welfare, requiring states that are applying less-stringent standards to 
take into account how air pollution above the level reflected by 
application of the BSER may impact the health and welfare of local 
communities furthers the statutory design. Other commenters agreed that 
the EPA has authority to require states to consider the impacts of 
less-stringent standards of performance on vulnerable communities but 
expressed concern that the lack of specificity of and guidance for 
implementing the proposed requirements would cause uncertainty among 
state regulators and impacted communities and lead to unequal 
application across states. Similarly, one commenter noted the 
differences between community impacts when considering localized 
pollutants versus regional or global pollutants and that impacts of the 
latter are more diffuse and difficult to assess. Some commenters, 
however, disagreed that the EPA has authority to require states to 
consider potential health and environmental impacts of less-stringent 
standards on vulnerable communities. These commenters generally 
asserted that the state-focused language of the RULOF provision in CAA 
section 111(d)(1) does not mandate an analysis of vulnerable 
communities and does not give the EPA power to force states to consider 
``other factors'' that it deems relevant.
    The EPA is not finalizing the proposed provisions at 40 CFR 
60.24a(k) as requirements under the general implementing regulations. 
We agree with commenters that additional specificity and guidance with 
regard to how states should consider the potential pollution impacts 
and benefits of control to communities most affected by and vulnerable 
to emissions from a designated facility invoking RULOF would be key to 
ensuring meaningful implementation of this provision. However, given 
the diversity of source categories, designated facilities, and 
designated pollutants that are regulated and could be regulated in CAA 
section 111(d), as well as the wide range of potential impacts on 
vulnerable communities that may result from less-stringent standards of 
performance under any given EG,\143\ the EPA does not believe it is 
either feasible or appropriate to prescribe a universally applicable 
approach or standard for approvability for this consideration. Instead, 
to protect all communities, including the most vulnerable ones, the EPA 
is finalizing a provision that will ensure that any less stringent 
standards of performance applied by states are no less stringent than 
necessary. Moreover, because consideration of health and environmental 
impacts is inherent in consideration of both the nonair quality health 
and environmental impacts and amount of emission reduction factors the 
EPA considers under CAA section 111(a)(1), when a state considers the 
systems of emission reduction identified in the applicable emission 
guideline using the factors and evaluation metrics the EPA considered 
in assessing those systems pursuant to RULOF, the state will 
necessarily consider the potential impacts and benefits of control to 
communities affected by a designated facility that is receiving a less-
stringent standard of performance.
---------------------------------------------------------------------------

    \143\ In the notice of proposed rulemaking, the EPA 
``recognize[d] that the consideration of communities in the standard 
setting process, such as what constitutes a benefit to a vulnerable 
community and what is a reasonable level of control, is highly 
dependent on the designated pollutant and source category subject to 
an EG.'' 87 FR 79203.
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    Thus, while the EPA is not promulgating a regulatory requirement in 
subpart Ba for states to consider the impacts of applying a less-
stringent standard of performance on the communities most affected by 
and vulnerable to emissions from a designated facility invoking RULOF, 
the EPA anticipates that states will consider these impacts. To this 
end, states may look to the EPA's emission guideline and its 
consideration of nonair quality health and environmental impacts and 
the amount of emission reductions available in determining the degree 
of emission limitation for guidance on considering the health and 
environmental impacts on communities affected by a designated facility 
for which RULOF has been invoked. Additionally, the procedural 
requirements under subpart Ba for meaningful engagement with pertinent 
stakeholders on state plan development that the EPA is finalizing will 
play an important role in RULOF. Meaningful engagement, which the EPA 
is defining as ``timely engagement with pertinent stakeholder 
representation in the plan development or plan revision process,'' 
\144\ and providing that ``[s]uch engagement should not be 
disproportionate in favor of certain stakeholders and should be 
informed by available best practices,'' should address, inter alia, the 
application of any less-stringent standards of performance pursuant to 
RULOF. Thus, the EPA intends for communities most affected by and 
vulnerable to the health and environmental impacts of pollution from a 
designated facility invoking RULOF to have an opportunity to 
participate in the process of determining how that facility is 
addressed in the relevant state plan. The EPA may also consider whether 
to promulgate requirements pertaining to consideration of impacts on 
vulnerable communities as part of an individual EG in the future, at 
which point it would

[[Page 80529]]

provide guidance on how to do so specific to the designated facilities 
and designated pollutant at issue.
---------------------------------------------------------------------------

    \144\ The EPA is also finalizing the proposed definition of 
``pertinent stakeholders'' to include those who are most affected by 
and vulnerable to the health or environmental impacts of pollution 
from the designated facilities addressed by the plan or plan 
revision.
---------------------------------------------------------------------------

g. Authority To Apply More Stringent Standards as Part of the State 
Plan
    The EPA, in the notice of proposed rulemaking, addressed two 
different sources of authority that would allow the Agency to approve 
state plans that include standards of performance that are more 
stringent than the degree of emission limitation determined by the EPA 
in the applicable EG. First, the EPA explained that allowing states to 
apply a more stringent standard of performance as part of their CAA 
section 111(d) plans is consistent with CAA section 116, which 
generally authorizes states to include more stringent standards of 
performance or requirements regarding control or abatement of air 
pollution in their plans. Second, the EPA proposed to interpretation 
the RULOF provision in CAA section 111(d)(1), and specifically the 
``other factors'' consideration, as allowing states to adopt more 
stringent standards of performance.\145\ As explained below, the EPA is 
not finalizing its proposed interpretation that states can use the 
RULOF provision in CAA section 111(d)(1) to adopt, and have the EPA 
approve, more stringent standards of performance in their state plans 
because, inter alia, states already have the authority and ability to 
do so under CAA section 116.
---------------------------------------------------------------------------

    \145\ 87 FR 79204-06.
---------------------------------------------------------------------------

    As explained in the notice of proposed rulemaking, the anti-
preemption requirements of CAA section 116 provide that nothing in the 
statute shall preclude or deny the right of states to adopt or enforce 
``any standard or limitation respecting emissions of air pollutants.'' 
While CAA section 116 clearly extends to a state adopting or enforcing 
a standard of performance more stringent than required under CAA 
section 111(d), the subpart Ba implementing regulations did not 
explicitly speak to whether the EPA can approve a state plan that 
includes such standard of performance. However, the EPA proposed to 
find that CAA section 116, as interpreted through the Supreme Court in 
Union Electric Co. v. EPA,\146\ requires the EPA to approve a state 
plan that includes more stringent standards of performance under CAA 
section 111(d). The EPA therefore proposed to modify the existing 40 
CFR 60.24a(f),\147\ clarifying that to the extent a state chooses to 
submit a plan that includes standards of performance that are more 
stringent or compliance schedules that are more rapid than the 
requirements of an EG, states have the authority to do so under this 
provision and CAA section 116. Further, the EPA proposed to clarify 
that it has the obligation, and therefore the authority, to review and 
approve such plans and render the more stringent requirements federally 
enforceable if all applicable requirements are met.
---------------------------------------------------------------------------

    \146\ 427 U.S. 246, 263-64 (1976).
    \147\ The existing provision at 40 CFR 60.24a(f) provides that 
``[n]othing in this subpart shall be construed to preclude any State 
or political subdivision thereof from adopting or enforcing,'' (1) 
standards of performance more stringent than an EG, or (2) 
compliance schedules requiring final compliance at earlier times 
than specified in an EG. In the proposed rulemaking, the EPA added 
several proposed provisions to 40 CFR 60.24a, which resulted in 
Sec.  60.24a(f), in addition to being amended, being renumbered as 
Sec.  60.24a(n). However, the EPA is not finalizing all the new 
provisions it proposed; as a result, erstwhile Sec.  60.24a(f) is 
now being finalized, with amendments, at Sec.  60.24a(i).
---------------------------------------------------------------------------

    The EPA is finalizing the proposed changes to the provision 
currently at 40 CFR 60.24a(f) which, as renumbered pursuant to this 
final rule, is now 40 CFR 60.24a(i). The Agency acknowledges that it 
previously took the position in the ACE Rule that Union Electric does 
not control the question of whether CAA section 111(d) state plans may 
be more stringent than Federal requirements. The EPA took this position 
in the ACE Rule on the basis that Union Electric on its face applies 
only to CAA section 110, and that it is ``potentially salient'' that 
CAA section 111(d) is predicated on specific technologies whereas CAA 
section 110 gives states broad latitude in the measures used for 
attaining the NAAQS.\148\ The EPA no longer takes this position. Upon 
further evaluation, the EPA finds that, because of the structural 
similarities between CAA sections 110 and 111(d), CAA section 116 as 
interpreted by Union Electric requires the EPA to approve CAA section 
111(d) state plans that are more stringent than required by the EG.
---------------------------------------------------------------------------

    \148\ 84 FR 32559-61.
---------------------------------------------------------------------------

    The Court in Union Electric rejected a construction of CAA sections 
110 and 116 that measures more stringent than those required to attain 
the NAAQS cannot be approved into a federally enforceable SIP but can 
be adopted and enforced only as a matter of state law. The Court found 
that such an interpretation of CAA section 116 ``would not only require 
the Administrator to expend considerable time and energy determining 
whether a state plan was precisely tailored to meet the Federal 
standards but would simultaneously require States desiring stricter 
standards to enact and enforce two sets of emission standards, one 
federally approved plan and one stricter state plan.'' 427 U.S. at 263-
64. The Court concluded there was no basis ``for visiting such wasteful 
burdens upon the States and the Administrator.'' Id. CAA sections 
111(d) and 110 are structurally similar in that both require the EPA to 
establish targets to meet the objectives of the respective sections 
(i.e., the degree of emission limitation set by an EG under CAA section 
111(d), and attainment and maintenance of the NAAQS under CAA section 
110), and states must adopt and submit to the EPA plans which include 
requirements to meet these targets. Specifically, the EPA establishes a 
presumptive standard of performance corresponding to the degree of 
emission limitation it has determined in an EG, and state plans under 
CAA section 111(d) must establish standards of performance that 
generally reflect this degree of emission limitation. Because CAA 
section 116 applies to ``any standard or limitation,'' this provision 
clearly applies to standards of performance adopted under CAA section 
111(d). Therefore, the Court's rationale in Union Electric as it 
pertains to the application of CAA section 116 in the context of the 
cooperative federalism structure of CAA section 110 also applies to CAA 
section 111(d). That is, the assessment of CAA section 116 in the 
context of requirements that states develop and submit to the EPA for 
evaluation against nationally applicable standards or criteria applies 
equally to CAA sections 110 and 111(d). On that basis, the EPA is 
finding that the Court's holding applies and controls the outcome here, 
as well. Requiring states to enact and enforce two sets of standards of 
performance, one that is exactly equal to the EPA's presumptive 
standard of performance that is federally approved as part of the CAA 
section 111(d) plan and one that is stricter and is only adopted and 
enforced as a matter state requirements, runs directly afoul of Union 
Electric's holding that there is no basis for interpreting CAA section 
116 in such manner.
    Moreover, there is nothing in CAA section 111(d) that precludes 
states from adopting, and EPA from approving, more stringent standards 
of performance.\149\ In fact, permitting

[[Page 80530]]

states to adopt more stringent standards of performance and include 
such standards in their state plans is entirely consistent with the 
purpose and structure of CAA section 111(d). States bear the obligation 
pursuant to CAA section 111(d)(1) to establish standards of 
performance. Nothing in CAA section 111(d) suggests that Congress 
intended to preclude states from determining that it is appropriate to 
regulate certain sources within their jurisdiction more strictly than 
otherwise required by Federal requirements. For the EPA to do so would 
be arbitrary and capricious in light of the overarching purpose of CAA 
section 111(d), which is to require emission reductions from existing 
sources for certain pollutants that endanger public health or welfare. 
It is inconsistent with the purpose of CAA section 111(d) and the role 
it confers upon states for the EPA to constrain them from further 
reducing emissions that harm their citizens, and the EPA does not see a 
reasonable basis for doing so.
---------------------------------------------------------------------------

    \149\ In the 1975 CAA section 111(d) implementing regulations 
the Agency explained that EPA's emission guidelines will reflect its 
judgment of the degree of control that can be attained by various 
classes of existing source without unreasonable costs. Particular 
sources within a class may be able to achieve greater control 
without unreasonable costs. Moreover, States that believe additional 
control is necessary or desirable will be free under section 116 of 
the Act to require more expensive controls, which might have the 
effect of closing otherwise marginal facilities, or to ban 
particular categories of sources outright. 40 FR 53343. Congress did 
nothing to disturb the understanding that states can use CAA section 
116 to adopt more stringent standards of performance when it enacted 
the 1977 CAA Amendments shortly thereafter.
---------------------------------------------------------------------------

    The EPA also included a second rationale for permitting more 
stringent standards of performance in the notice of proposed 
rulemaking. The Agency explained that CAA section 111(d)(1) provides 
that states are permitted to consider remaining useful life and other 
factors ``in applying a standard of performance to any particular 
source under a plan,'' but does not specify that the source-specific 
standard must be a less stringent standard of performance. Aside from 
the explicit reference to remaining useful life, the statute is silent 
as to what the ``other factors'' are that states may consider in 
applying a standard of performance and whether such factors can be used 
only to weaken the stringency of a standard of performance for a 
particular designated facility. Therefore, in addition to proposing 
that states may include, and the EPA must approve, more stringent 
standards of performance in state plans pursuant to CAA sections 111(d) 
and 116, the EPA also proposed to interpret CAA section 111(d)(1) as 
allowing states to consider ``other factors'' in exercising their 
discretion to apply a more stringent standard to a particular source. 
The Agency acknowledged that it had previously, in promulgating subpart 
Ba in 2019, taken the position that the statutory RULOF provision 
authorizes only standards of performance that are less stringent than 
the presumptive level of stringency required by a particular EG,\150\ 
and explained why it was proposing to change course. To codify its 
revised interpretation of the RULOF provision, the EPA proposed 
explicit regulatory text that would have allowed states to use RULOF, 
and specifically, ``other factors,'' to apply a more stringent standard 
of performance. The new provision at 40 CFR 60.24a(m) would have also 
required that state plans include an adequate demonstration that the 
standard of performance is more stringent than required by an 
application EG and meet all other applicable requirements.
---------------------------------------------------------------------------

    \150\ See EPA's Responses to Public Comments on the EPA's 
Proposed Revisions to Emission Guideline Implementing Regulations at 
56 (Docket ID No. EPA-HQ-OAR-2017-0355-26740) (July 8, 2019).
---------------------------------------------------------------------------

    The EPA received comments both in support of and opposed to its 
proposed interpretation that states may apply more stringent standards 
of performance and that EPA has an obligation to approve such standards 
in state plans. Several commenters stated the Agency has appropriately 
interpreted CAA section 116 and 111(d), as well as Union Electric Co. 
v. EPA, as allowing states to submit, and the EPA to approve, more 
stringent standards. One commenter also agreed that the statutory 
phrase ``remaining useful life and other factors'' does not foreclose a 
state plan from applying a more stringent standard of performance to a 
particular source; while ``remaining useful life'' implies a less 
stringent standard, ``other factors'' does not. Another commenter 
asserted that the EPA need not rely on ``other factors'' to permit 
states to apply more stringent standards because states already have 
the ability to do so in light of the Supreme Court's ruling in Union 
Electric. Commenters that disagreed with the EPA's proposed 
interpretation generally recognized that states can adopt more 
stringent rules than those required by the EPA but asserted that the 
CAA does not authorize the EPA to approve them into state plans and 
thus make them federally enforceable. One commenter argued that the 
EPA's BSER determination defines the extent of both EPA and state 
authority under CAA section 111 and that the RULOF provision does not 
authorize states to select a different, more stringent BSER under the 
guise of RULOF. Another commenter stated that the EPA's position that 
RULOF is a variance provision for sources that cannot meet the BSER due 
to limited remaining useful life or other factors is in tension with 
its interpretation that the same provision provides a broad grant of 
authority for states to impose more stringent standards on sources. The 
same commenter pointed out the difference in proposed requirements for 
states invoking RULOF to apply a less stringent standard and those for 
applying a more stringent standard.
    The EPA agrees with commenters that it need not rely on ``other 
factors'' for authority to permit states to submit, and the EPA to 
approve, more stringent standards of performance in state plans. As 
explained above, CAA sections 116 and 111(d), and the Court's 
interpretation in Union Electric of section 116 as it relates to CAA 
section 110's analogous statutory framework, provide a sufficient basis 
this position. Moreover, upon further consideration of the history of 
the RULOF provision and the EPA's interpretation of that provision as a 
variance for states to use when a source cannot reasonably achieve the 
degree of emission limitation determined by the EPA, the Agency is not 
finalizing its proposed interpretation that the RULOF provision allows 
states to adopt more stringent standards of performance in their plans. 
The EPA is therefore not finalizing the provision it proposed at 40 CFR 
60.24a(m) that would have explicitly allowed a state to ``account for 
other factors in applying a standard of performance that is more 
stringent than required by an applicable emission guideline, or the 
proposed provision that ``[t]he plan must include an adequate 
demonstration that the standard of performance is more stringent than 
required by an applicable emission guideline, and must meet all other 
applicable requirements, such as those that provide for the 
implementation and enforceable of the more stringent standard of 
performance.'' As a general matter, states already bear the burden of 
demonstrating that their standards of performance are no less stringent 
than the corresponding EG. See 40 CFR 60.24a(c).
    The EPA disagrees with comments suggesting that the EPA's BSER 
determination is the ceiling--that the EPA is constrained from 
approving more stringent standards of performance into state plans. As 
explained above, there is no support for this position in the statutory 
language or structure of CAA section 111(d). It is also inconsistent 
with CAA section 116 and would run counter to the purpose of section 
111--reducing emissions of dangerous air pollutants from designated 
facilities.

[[Page 80531]]

    The EPA anticipates that, in many cases, more stringent standards 
of performance would entail marginal differences in stringency between 
the degree of emission limitation in the applicable EG and the state 
plan requirement. For example, the EPA may determine that, for the 
source category in general, a control technology can reasonably achieve 
an 80% reduction in emissions, while a state finds that at a particular 
designated facility, that same control technology can reasonably 
achieve a 90% reduction. Or a state may decide that a particular 
designated facility can install a control technology that has already 
been demonstrated to reasonably achieve greater emission reductions 
than the BSER the EPA determined for the source category generally. The 
EPA also notes that approving more stringent standards of performance 
in state plans is not a new practice under subpart Ba; for example, in 
2020 the EPA approved more stringent standards of performance that 
California submitted as part of its CAA section 111(d) state plan to 
implement the emission guidelines for landfill gas emissions from 
municipal solid waste landfills. These more stringent standards of 
performance were incorporated into the Code of Federal Regulations and 
thus became federally enforceable.\151\
---------------------------------------------------------------------------

    \151\ 40 CFR 62.1100(b)(7); 85 FR 1121 (Jan. 9, 2020); see also 
``Appendix E: Comparison of the Major Provisions of the Emission 
Guidelines and California's Landfill Methane Regulation,'' EPA-R09-
OAR-2019-0393-0008 (technical support document for EPA action on 
California's CAA section 111(d) state plan to implement the EG for 
landfill gas from municipal solid waste landfills).
---------------------------------------------------------------------------

    In summary, the EPA is finalizing, at 40 CFR 60.24a(i), the 
proposed revisions to the existing provision (currently at 40 CFR 
60.24a(f)) stating that nothing in subpart Ba shall be construed to 
preclude any state from adopting or enforcing, as part of a state plan, 
(1) standards of performance more stringent that the applicable EG, or 
(2) compliance schedules requiring final compliance at earlier times 
than specified in the applicable EG. The EPA is not finalizing the 
regulatory text provision proposed at 40 CFR 60.24a(m) stating that a 
state may account for other factors in applying a more stringent 
standard of performance.

F. Provision for Electronic Submission of State Plans

    The EPA proposed to revise subpart Ba to require electronic 
submission of state plans instead of paper copies.\152\ As explained in 
the notice of proposed rulemaking, the regulations promulgated in 2019 
require state plan submissions to be made in accordance with 40 CFR 
60.4. Pursuant to 40 CFR 60.4(a), all requests, reports, applications, 
submittals, and other communications to the Administrator pursuant to 
40 CFR part 60 shall be submitted in duplicate to the appropriate 
regional office of the EPA. The provision in 40 CFR 60.4(a) then 
proceeds to list the corresponding addresses for each regional office. 
The EPA proposed that, rather than requiring paper copies of state plan 
submissions to be sent to the appropriate regional office, states would 
submit their state plans electronically via the use of its State 
Planning Electronic Collaboration System (SPeCS).
---------------------------------------------------------------------------

    \152\ 87 FR 79206.
---------------------------------------------------------------------------

    As previously described, CAA section 111(d) requires the EPA to 
promulgate a ``procedure'' similar to that of CAA section 110 under 
which states submit plans. The statute does not prescribe a specific 
platform for plan submissions, and the EPA reasonably interprets the 
procedure it must promulgate under the statute as allowing it to 
require electronic submission. Requiring electronic submission is 
reasonable for the following reasons. Providing for electronic 
submittal of CAA section 111(d) state plans in subpart Ba in place of 
paper submittals aligns with current trends in electronic data 
management and as implemented in the individual EGs will result in less 
burden on the states. It is the EPA's experience that the electronic 
submittal of information increases the ease and efficiency of data 
submittal and data accessibility. The EPA's experience with the 
electronic submittal process for SIPs under CAA section 110 has been 
successful as all the states are now using the SPeCS, which is a user-
friendly, web-based system that enables state air agencies to 
officially submit SIPs and associated information electronically for 
review and approval to meet their CAA obligations related to attaining 
and maintaining the NAAQS. SPeCS for SIPs is the EPA's preferred method 
for receiving such SIPs submissions. The EPA has worked extensively 
with state air agency representatives and partnered with E-Enterprise 
for the Environment and the Environmental Council of the States to 
develop this integrated electronic submission, review, and tracking 
system for SIPs. SPeCS can be accessed by the states through the EPA's 
Central Data Exchange (CDX) (https://cdx.epa.gov/). The CDX is the 
Agency's electronic reporting site and performs functions for receiving 
acceptable data in various formats. The CDX registration site supports 
the requirements and procedures set forth under the EPA's Cross-Media 
Electronic Reporting Regulation, 40 CFR part 3.
    Most of the commenters were supportive of the proposed amendments 
for electronically submitting state plans. However, a few commenters 
expressed that EPA should provide an option to submit state plans in 
paper format. The EPA has determined that submitting state plans 
electronically is more efficient and less burdensome than paper 
submittals. States already submit state implementation plans 
electronically via SPeCS so there should be little to no additional 
burden associated with using it for state plans. Additionally, having 
some states submit state plans via SPeCS and other states mail hard-
copy plans to regional offices would undermine many of the efficiencies 
provided to the EPA through the use of electronic submission and could 
result in confusion. One commenter recommended adding language to 
clarify that a Negative Declaration letter submitted in accordance with 
40 CFR 60.23a(b) can also be submitted via SPeCS. The EPA agrees with 
the need to add the electronic submittal language to 40 CFR 60.23a(b) 
identified by the commenter and has added the language in the final 
rule so that the states submit the Negative Declaration letter using 
the SPeCS, or through an analogous electronic reporting tool provided 
by the EPA for the submission of any plan required by this subpart.
    The EPA is therefore finalizing the requirements for electronic 
submittal of state plans in 40 CFR 60.23a(a)(1) and (3). As finalized, 
40 CFR 60.23a(a)(1) provides: ``The submission of such plan shall be 
made in electronic format according with Sec.  60.23a(a)(3) or as 
specified in an applicable emission guideline.'' The regulation at 40 
CFR 60.23a(a)(3) in turn contains the general requirements associated 
with the electronic submittal of a state plan in subpart Ba via the use 
of SPeCS or through an analogous electronic reporting tool provided by 
the EPA for the submission of any plan required by subpart Ba. The EPA 
is also including at 40 CFR 60.23a(a)(3) language to specify that 
states are not to transmit confidential business information (CBI) 
through SPeCS. Even though state plans submitted to the EPA for review 
and approval pursuant to CAA section 111(d) through SPeCS are not to 
contain CBI, the language at 40 CFR 60.23a(a)(3) also addresses the 
submittal of CBI in the event there is a need for such information to 
be submitted to the EPA.

[[Page 80532]]

    Any other specific requirements associated with the electronic 
submittal of a particular state plan will be provided within the 
corresponding EG. The requirements for electronic submission of CAA 
section 111(d) state plans in EGs will ensure that these Federal 
records are created, retained, and maintained in electronic format. 
Electronic submittal will also improve the Agency's efficiency and 
effectiveness in the receipt and review of state plans. The electronic 
submittal of state plans may also provide continuity in the event of a 
disaster like the one our nation experienced with COVID-19.

G. Other Proposed Modifications and Clarifications

1. Standard of Performance and Compliance Flexibility
a. Definition of Standard of Performance
    The EPA proposed amendments to 40 CFR 60.21a(f) and 60.24a(b) to 
clarify that the definition of ``standard of performance'' allows for 
state plans to include standards in the form of an allowable mass limit 
of emissions. As explained in the notice of proposed rulemaking,\153\ 
the amendments were intended to harmonize these regulatory definitions 
with the definitions of ``emission limitation'' and ``emission 
standard'' in CAA section 302(k), which is ``a requirement established 
by the State or the Administrator which limits the quantity, rate, or 
concentration of emissions of air pollutants on a continuous basis, 
including any requirement relating to the operation or maintenance of a 
source to assure continuous emission reduction, and any design, 
equipment, work practice, or operational standard promulgated under 
this chapter.'' While the EPA had intended the phrase ``allowable rate 
or limit of emissions'' in the existing regulatory definitions to 
encompass the full range of forms included in the statute, to eliminate 
any potential confusion the Agency proposed to make this explicit.
---------------------------------------------------------------------------

    \153\ 87 FR 79176, 79206-07 (Dec. 23, 2022).
---------------------------------------------------------------------------

    Most comments received on the proposed revision to the definition 
of ``standard of performance'' were in support of these amendments. 
Some commenters pointed out that the revision would be consistent with 
the statutory definition in CAA section 302(k) and many expressed 
approval that the revised definition would clearly allow for standards 
of performance to take the form of mass-based emission limits. Several 
commenters stressed that, while they supported the proposed definition 
of standard of performance for subpart Ba, the appropriate form of the 
standard of performance in any particular EG must be determined in the 
context of that EG. Some commenters expressed concern that the proposed 
revision would allow the EPA to define the BSER as a trading program 
for any source sector, or for states and the EPA to impose emissions 
averaging and trading programs in CAA section 111(d) plans.
    The EPA is finalizing amendments to 40 CFR 60.21a(f) and 60.24a(b) 
as proposed. The Agency's interpretation of CAA section 111 with regard 
to emissions trading or averaging is a separate matter that is 
discussed in section III.G.1.b. of this preamble; it is reiterated that 
the revisions to the definition of standard of performance are being 
made to align it with the statutory definition of emission limitation 
and emission standard in CAA section 302(k) for the purpose of these 
general implementing regulations. The EPA agrees with commenters that 
the appropriate form of the standard of performance in any particular 
EG must be determined in the context of that EG, and the EPA may choose 
to prescribe the acceptable form or forms of the standard of 
performance in an individual EG. In addition to finalizing the proposed 
amendments to 40 CFR 60.21a(f) to clarify that the term ``an allowable 
rate or limit of emissions'' means ``an allowable rate, quantity, or 
concentration of emissions'' of air pollutants, the EPA is also 
finalizing its proposed removal of the phrase ``but not limited to'' 
from 40 CFR 60.21a(f) as unnecessary and potentially confusing verbiage 
that is redundant of the word ``including,'' particularly where the 
definition already identifies a wide breadth of potential standards 
that may be included in a state plan. Moreover, the EPA is finalizing 
amendments to the definition of standard of performance under 40 CFR 
60.24a(b) to read ``. . . in the form of an allowable rate, quantity, 
or concentration of emissions'' rather than ``. . . either be based on 
allowable rate or limit of emission.''
b. Compliance Flexibilities, Including Trading or Averaging
    The EPA is finalizing its proposal that CAA section 111(a) and (d) 
cannot be interpreted, by their terms, to limit the types of controls 
that states, in their state plans, may authorize their sources to adopt 
to at-the-source, and thereby preclude states from authorizing their 
sources flexibilities such as trading or averaging. Under the 
provisions of CAA section 111(a) and (d), and consistent with the 
federalism principles that underlie the CAA, states have broad 
authority to determine the types of control measures for their sources, 
including trading or averaging, although the EPA may establish 
constraints to protect the integrity of particular EGs. The EPA is also 
finalizing its proposal that CAA section 111 cannot be interpreted, by 
its terms, to limit the ``best system of emission reduction . . . 
adequately demonstrated'' (BSER) to at-the-source measures. As the EPA 
explains, many control measures that the EPA has determined to be the 
BSER in prior rules have outside-the-source components. The EPA is 
finalizing its repeal of the ACE Rule's contrary interpretations of CAA 
section 111.
    In the proposal, the EPA provided a brief summary of the applicable 
CAA provisions, the ACE Rule, the D.C. Circuit's decision reversing the 
ACE Rule, and the U.S. Supreme Court's decision vacating the D.C. 
Circuit's vacatur of the ACE Rule.\154\ For convenience, parts of that 
summary are reproduced here.
---------------------------------------------------------------------------

    \154\ 87 FR 79176, 79207-08 (Dec. 23, 2022).
---------------------------------------------------------------------------

    i. CAA section 111. Under CAA section 111(d)(1), each state is 
required to submit to the EPA ``a plan which . . . establishes 
standards of performance for any existing source'' that emits certain 
types of air pollutants, and which ``provides for the implementation 
and enforcement of such standards of performance.'' Under CAA section 
111(a)(1), a ``standard of performance'' is defined as ``a standard for 
emissions of air pollutants which reflects the degree of emission 
limitation achievable through the application of the best system of 
emission reduction . . . adequately demonstrated.''
    ii. Rulemaking and caselaw. In the Clean Power Plan (CPP), the EPA 
interpreted the term ``system'' in CAA section 111(a)(1) to be broad 
and therefore to authorize the EPA to consider a wide range of measures 
from which to select the BSER.\155\ Similarly, the CPP took the 
position that states had broad flexibility in choosing compliance 
measures for their state plans.\156\ The CPP went on to determine that 
generation shifting qualified as the BSER,\157\ and that states could 
include trading or averaging programs in their state plans for 
compliance.\158\
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    \155\ 80 FR 64662, 64720 (October 23, 2015).
    \156\ See, e.g., id. at 64887.
    \157\ Id. at 64707.
    \158\ Id. at 64840.
---------------------------------------------------------------------------

    The ACE Rule included the repeal of the CPP. It interpreted CAA 
section 111 so that the type of ``system'' that the EPA may select as 
the BSER is limited to a control measure that could be

[[Page 80533]]

applied at each source (that is, inside the fenceline of each source) 
to reduce emissions at each source.\159\ The ACE Rule also concluded 
that the compliance measures the states include in their plans must 
``correspond with the approach used to set the standard in the first 
place,'' \160\ and therefore must also be limited to inside-the-
fenceline measures that reduce the emissions of each source. For these 
reasons, the ACE Rule invalidated the CPP's generation-shifting system 
as the BSER, on grounds that it was an outside the source measure, and 
precluded states from allowing their sources to trade or average to 
demonstrate compliance with their emission standards.\161\
---------------------------------------------------------------------------

    \159\ 84 FR 32520, 32523-24 (July 8, 2019).
    \160\ Id. at 32556.
    \161\ Id. at 32556-57.
---------------------------------------------------------------------------

    In 2021, the D.C. Circuit vacated the ACE Rule.\162\ The court 
held, among other things, that CAA section 111(d) does not limit the 
EPA, in determining the BSER, to at-the- source measures.\163\ The 
court further held that the ACE Rule's premise for viewing compliance 
measures as limited to at the source measures, which is that BSER 
measures are so limited, was invalid for the same reason. The court 
indicated that while requiring symmetry between the nature of the BSER 
and compliance measures ``would be reasonable'' where necessary to 
preserve the environmental outcomes a particular BSER was designed to 
achieve, a universal restriction on compliance measures could not be 
sustained by policy concerns that were not similarly universal.\164\
---------------------------------------------------------------------------

    \162\ American Lung Ass'n v. EPA, 985 F.3d 914 (D.C. Cir. 2021).
    \163\ Id. at 944-51
    \164\ Id. at 957-58.
---------------------------------------------------------------------------

    In 2022, the U.S. Supreme Court reversed the D.C. Circuit's vacatur 
of the ACE Rule's embedded repeal of the Clean Power Plan.\165\ The 
Supreme Court made clear that CAA section 111 authorizes the EPA to 
determine the BSER and the amount of emission limitation that state 
plans must achieve.\166\ However, the Supreme Court invalidated the 
CPP's generation-shifting BSER under the major question doctrine, 
explaining that the term ``system'' does not provide the ``clear 
congressional authorization'' needed to support a BSER ``of such 
magnitude and consequence.'' \167\ The Court declined to address the 
D.C. Circuit's decision that the text of CAA section 111 did not limit 
the type of ``system'' the EPA could consider as the BSER to at-the-
source measures.\168\ Nor did the Court rule on the scope of the 
states' compliance flexibilities.
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    \165\ West Virginia v. EPA, 142 S. Ct. 2587 (2022).
    \166\ Id. at 2601-02.
    \167\ Id. at 2614-16 (internal quotation marks omitted).
    \168\ See id. at 2615 (``We have no occasion to decide whether 
the statutory phrase `system of emission reduction' refers 
exclusively to measures that improve the pollution performance of 
individual sources, such that all other actions are ineligible to 
qualify as the BSER.'' (emphasis omitted)).
---------------------------------------------------------------------------

    iii. Proposal. In the proposal, the EPA stated that it has 
reconsidered the ACE Rule's interpretation of the compliance 
flexibilities available to states under CAA section 111 and that it was 
proposing to disagree with the rule's view that trading or averaging 
are universally precluded \169\ and that state plan compliance measures 
must always correspond with the approach the EPA uses to set the BSER. 
The EPA added, however, that the flexibility that CAA section 111(d) 
grants to states in adopting measures for their state plans is not 
unfettered; rather, CAA section 111(d)(2) requires the EPA to review 
state plans to ensure that they are ``satisfactory,'' and the EPA may 
conclude in particular emission guidelines that limiting the types of 
control measures states may authorize their sources to adopt, including 
precluding trading or averaging, are necessary to protect the 
environmental outcomes of the emission guidelines.\170\
---------------------------------------------------------------------------

    \169\ With respect to averaging, the ACE Rule noted that the 
D.C. Circuit has recognized that the EPA may have statutory 
authority under CAA section 111 to allow plant-wide emissions 
averaging, See U.S. Sugar v. EPA, 830 F.3d 579, 627 n.18 (D.C. Cir. 
2016) (pointing to the definition of ``stationary source''), but 
stated that the Agency's determination that individual EGUs are 
subject to regulation under ACE precludes the Agency from attempting 
to change the basic unit from an EGU to a combination of EGUs for 
purposes of ACE implementation.
    \170\ 87 FR 79208.
---------------------------------------------------------------------------

    In addition, the EPA also proposed to reject the ACE Rule's 
interpretation that various provisions in CAA section 111 limit the 
type of ``system'' that may qualify as the BSER to at-the-source 
measures.\171\ The EPA explained that it proposed to agree with the 
part of the D.C. Circuit's decision in American Lung Ass'n,\172\ that 
rejected the ACE Rule's at-the-source statutory interpretation. The EPA 
added that it recognized that the Supreme Court, in West Virginia, did 
impose limits, through the application of the major question doctrine, 
on the type of ``system'' that may qualify as the BSER.\173\ The EPA 
made clear that it was not proposing to address the scope of the limits 
that may result from application of the major question doctrine, and 
thus was not proposing to address whether it could include trading or 
averaging as part of the BSER, or to identify any particular control 
mechanism that could or could not be part of a specific BSER, in light 
of those limits. Instead, the EPA stated that it may address further 
those limits, and their implications for the legality of particular 
systems of emission reduction and state compliance measures, in future 
emission guidelines.\174\
---------------------------------------------------------------------------

    \171\ 84 FR 32556.
    \172\ 985 F.3d at 944-51.
    \173\ 142 S. Ct. at 2615-16.
    \174\ 87 FR 79208.
---------------------------------------------------------------------------

    iv. The EPA's finalized interpretation of state authority to grant 
compliance flexibilities. The EPA is finalizing its proposal that, 
contrary to the position of the ACE Rule, CAA section 111 does not 
preclude states from including compliance flexibilities such as trading 
or averaging for their sources in their state plans, although in 
particular emission guidelines the EPA may limit those flexibilities if 
necessary to protect the environmental outcomes of the guidelines. The 
EPA is also rescinding the related ACE Rule interpretation that CAA 
section 111 requires that state plan measures be symmetrical to the 
types of measures the EPA included in the BSER.
    Most commenters agreed with the proposal that CAA section 111 does 
not preclude states from including compliance flexibilities in their 
state plans. However, several commenters disagreed and submitted 
adverse comments. Some commenters stated that West Virginia is clear 
that the EPA cannot include generation-shifting as the BSER, and then 
argued that the EPA cannot include trading as part of the BSER because 
trading entails generation shifting, and then further argued that for 
emission guidelines applicable to electric generating units, the EPA 
cannot authorize trading as a compliance mechanism because trading 
incentivizes generation shifting to occur and only works if generation 
shifting does occur. As explained further below, the EPA does not 
believe that these adverse comments cast doubt on the rationale that it 
gave in the proposal for why states have the authority to allow 
compliance flexibilities such as trading or averaging.\175\ The EPA 
continues to agree with the reasoning in American Lung Ass'n,\176\ in 
rejecting the ACE Rule's limitations on those measures.
---------------------------------------------------------------------------

    \175\ Id.
    \176\ 985 F.3d at 957-58.
---------------------------------------------------------------------------

    To review the reasons that the ACE Rule gave for asserting that 
trading or averaging across designated facilities is inconsistent with 
CAA section 111: The ACE Rule stated that those options would not 
necessarily require any emission reductions from designated

[[Page 80534]]

facilities and may not actually reflect application of the BSER. The 
ACE Rule explained that ``state plans must establish standards of 
performance--which by definition `reflects . . . the application of the 
best system of emission reduction,' '' \177\ and then asserted that 
implementation and enforcement of such standards should be based on 
improving the emissions performance of sources to which a standard of 
performance applies. The ACE Rule added that trading or averaging would 
effectively allow a state to establish standards of performance that do 
not reflect application of the BSER, and gave, as an example, the 
possibility that under a trading program, a single source could 
potentially shut down or reduce utilization to such an extent that its 
reduced or eliminated operation generates sufficient allowances for a 
state's remaining sources to meet their standards of performance 
without themselves making any emission reductions from any other 
source. The ACE Rule asserted that this compliance strategy would 
undermine the EPA's determination of the BSER.\178\
---------------------------------------------------------------------------

    \177\ This paraphrasing by the ACE Rule of the CAA section 
111(a)(1) definition of ``standard of performance'' is incomplete--a 
``standard of performance'' ``reflects the degree of emission 
limitation achievable through the application of the best system of 
emission reduction.''
    \178\ 84 FR 32557.
---------------------------------------------------------------------------

    This interpretation of CAA section 111 is unduly strained and the 
EPA rejects it. The provisions of CAA section 111(d) by their terms do 
not affirmatively bar states from considering trading or averaging as a 
compliance measure where appropriate for a particular emission 
guideline. Under CAA section 111(d)(1), each state must ``establish[ 
],'' ``implement[ ],'' and ``enforce[ ]'' ``standards of performance 
for any existing source.'' A state plan may ``establish[ ]'' a standard 
of performance for each source that constitutes an emissions standard 
that reflects the amount of emission reduction that the source could 
achieve by applying the BSER, but the state may also allow measures 
like trading or averaging as potential means of compliance. Nothing in 
the text of CAA section 111 precludes states from considering a 
source's acquisition of allowances as part of a trading program in 
``implement[ing]'' and ``enforce[ing]'' a standard of performance for 
that particular source, so long as the state plan achieves the required 
overall level of emission reductions.\179\ CAA section 111(d)(1) 
requires only that each source comply with its standard, not that each 
source do so through applying the BSER. By the same token, contrary to 
the ACE Rule,\180\ CAA section 111(d)(1) does not limit the states to 
compliance measures that are symmetrical to what the EPA determined to 
be the BSER unless necessary to preserve the environmental outcomes a 
particular system was designed to achieve.
---------------------------------------------------------------------------

    \179\ This overall level of emissions reduction is the level 
that would be achieved if each source were to apply the BSER.
    \180\ 84 FR 32556 (ACE Rule states that one reason why CAA 
section 111 precludes states from authorizing trading or averaging 
is that ``[a]pplying an implementation approach that differs from 
standard-setting would result in asymmetrical regulation'').
---------------------------------------------------------------------------

    For further support for the interpretation that CAA section 111 
does not preclude states from authorizing compliance flexibilities such 
as trading or averaging, the EPA notes that CAA section 111(d)(1) 
requires a ``procedure similar to that provided by [CAA section 110].'' 
\181\ Consideration of the CAA section 110 framework reinforces the 
absence of any mandate that states consider only compliance measures 
that apply at and to an individual source. ``States have `wide 
discretion' in formulating their plans'' under section 110.\182\ The 
EPA has authorized trading programs in CAA section 110 SIPs for 
decades. See Economic Incentive guidance.\183\
---------------------------------------------------------------------------

    \181\ See CAA section 111(d)(2)(A) (referring to CAA section 
110(c)), 111(d)(2)(B) (referring to enforcement of state 
implementation plans (SIPs)).
    \182\ Alaska Dep't of Envtl. Conservation v. EPA, 540 U.S. 461, 
470 (2004) (citation omitted); see Union Elec. Co. v. EPA, 427 U.S. 
246, 269 (1976) (``Congress plainly left with the States, so long as 
the national standards were met, the power to determine which 
sources would be burdened by regulation and to what extent.''); 
Train v. Natural Res. Def. Council, Inc., 421 U.S. 60, 79 (1975) 
(``[S]o long as the ultimate effect of a State's choice of emission 
limitations is compliance with the national standards for ambient 
air, the State is at liberty to adopt whatever mix of emission 
limitations it deems best suited to its particular situation.'').
    \183\ The ACE Rule stated that the reference in CAA section 
111(d)(1) to CAA section 110 was limited to the procedure under 
which states shall submit plans to the EPA, and asserted that it 
does not imply anything about implementation mechanisms available 
under CAA section 111(d). 84 FR 32557. The EPA believes that the 
several references to CAA section 110 in CAA section 111(d)(1) and 
(2), as noted in the accompanying text, support the view that 
Congress intended that state plans under CAA section 111(d) would be 
similar to state plans under CAA section 110, including retaining 
the authority to grant sources compliance flexibility in appropriate 
circumstances.
---------------------------------------------------------------------------

    Such flexibility is consistent with the framework of cooperative 
federalism that CAA section 111(d) establishes, which vests states with 
substantial discretion in establishing control requirements for their 
sources. As the U.S. Supreme Court has explained, CAA section 111(d) 
``envisions extensive cooperation between Federal and state 
authorities, generally permitting each State to take the first cut at 
determining how best to achieve EPA emissions standards within its 
domain.'' \184\
---------------------------------------------------------------------------

    \184\ American Elec. Power Co. v. Connecticut, 564 U.S. 410, 428 
(2011) (citations omitted).
---------------------------------------------------------------------------

    This interpretation is also consistent with the EPA's consistent 
views prior to the ACE Rule. The EPA authorized trading or averaging as 
compliance methods in the 2005 Clean Air Mercury Rule for coal-fired 
EGUs,\185\ and the 2015 Clean Power Plan (CPP).\186\
---------------------------------------------------------------------------

    \185\ 70 FR 28606, 28617 (May 18, 2005), vacated on other 
grounds, New Jersey v. EPA, 517 F.3d 574 (D.C. Cir. 2008), see 40 
CFR 60.24(b)(1) (2005) (providing that a state's ``[e]mission 
standards [may] be based on an allowance system), repealed in the 
ACE Rule.
    \186\ 80 FR 64662, 64840 (October 23, 2015), repealed by the ACE 
Rule. 87 FR 79208.
---------------------------------------------------------------------------

    It must be emphasized that the EPA retains an important role in 
reviewing state plans for adequacy. Under CAA section 111(d)(2)(A), the 
EPA must determine that the state plan is ``satisfactory'' and, if the 
state plan is not satisfactory or if the state does not submit a state 
plan, the EPA must promulgate a plan that establishes Federal standards 
of performance for the State's existing sources. Thus, the flexibility 
that CAA section 111(d)(1) grants to states in adopting measures for 
their state plans is not unfettered. As the Supreme Court stated in 
West Virginia, ``The Agency, not the States, decides the amount of 
pollution reduction that must ultimately be achieved.'' \187\ The Court 
further stated that state plans must contain ``emissions restrictions 
that they intend to adopt and enforce in order not to exceed the 
permissible level of pollution established by EPA.'' \188\ Thus, the 
EPA retains the authority to ensure that the permissible level of 
pollution is not exceeded by any state plan. If the EPA considers that 
compliance flexibility measures would compromise the ability of the 
state plan to achieve the environmental outcomes the best system could 
achieve, the EPA may, in the emission guidelines, preclude such 
measures or otherwise conclude that the state plan is not satisfactory.
---------------------------------------------------------------------------

    \187\ 142 S. Ct. at 2602.
    \188\ Id.
---------------------------------------------------------------------------

    In West Virginia v. EPA, the Supreme Court did not directly address 
the state's authority to determine their sources' control measures. 
Although the Court did hold that constraints apply to the EPA's 
authority in determining the BSER, the Court's discussion of CAA 
section 111 is consistent with the EPA's interpretation that the 
provision does not preclude states from granting sources compliance 
flexibility.
    At the outset of the decision, the Court made clear CAA section 111

[[Page 80535]]

provides different roles for the EPA and the States:

    Although the States set the actual rules governing existing 
power plants, EPA itself still retains the primary regulatory role 
in Section 111(d). The Agency, not the States, decides the amount of 
pollution reduction that must ultimately be achieved. It does so by 
again determining, as when setting the new source rules, ``the 
[BSER]. . . . The States then submit plans containing the emissions 
restrictions that they intend to adopt and enforce in order not to 
exceed the permissible level of pollution established by EPA.\189\
---------------------------------------------------------------------------

    \189\ West Virginia v. EPA, 142 S.Ct. at 2601-02 (citations 
omitted).

    The Court was clear that the focus of the case was exclusively on 
the EPA's role, that is, whether the EPA acted within the scope of its 
authority in establishing the BSER.\190\ The Court applied the major 
question doctrine to hold that the generation-shifting BSER that the 
EPA promulgated in the CPP exceeded the constraints of the CAA section 
111 BSER provisions, in light of ``separation of powers principles and 
a practical understanding of legislative intent.'' \191\ The Court did 
not identify any constraints on the states in establishing standards of 
performance to their sources, and its holding and reasoning cannot be 
extended to apply such constraints. In fact, the Supreme Court at least 
implicitly recognized that CAA section 111(d) does not preclude states 
from authorizing sources compliance flexibility when the Court observed 
that a new or modified source ``may achieve [the EPA-determined] 
emissions [standard] any way it chooses.'' \192\ There is no reason why 
existing sources should have less flexibility.
---------------------------------------------------------------------------

    \190\ Id. at 2600 (``The question before us is whether this 
broad[ ] conception of EPA's authority [to determine the BSER] is 
within the power granted to it by the Clean Air Act.'').
    \191\ Id. at 2609.
    \192\ Id. at 2601.
---------------------------------------------------------------------------

    It should also be noted that the adverse commenters described above 
are incorrect in their view that trading necessarily results in 
generation shifting and that the logic of the West Virginia decision 
precludes any such generation shifting. As just noted, the reasons why 
the Court held that the CPP's generation-shifting BSER violated the 
major question doctrine and thus was invalid have no application to 
states in developing state plans. In addition, the Court was clear that 
a BSER that has the incidental effect of resulting in generation 
shifting would not, on those grounds, violate the major question 
doctrine. The Court emphasized that ``there is an obvious difference 
between (1) issuing a rule that may end up causing an incidental loss 
of coal's market share, and (2) simply announcing what the market share 
of coal, natural gas, wind, and solar must be, and then requiring 
plants to reduce operations or subsidize their competitors to get 
there.'' \193\ The second option is what the Court viewed the CPP's 
generation-shifting BSER as attempting to do, which thereby triggers 
the major question doctrine. But, as a coalition of companies that 
operate electricity generation as well as transmission and distribution 
systems commented, the Court ``evinced no general concern about option 
1, which is an inevitable consequence of regulation within the power 
sector, in which all sources of emissions are interconnected and 
increase or decrease their generation based upon demand for electricity 
and other sources' availability.'' \194\ If the Court in West Virginia 
had little concern with the EPA determining a BSER that has the 
incidental effect of shifting generation, there is no basis for reading 
the case to preclude a state from adopting trading measures in its 
state plan on grounds that those measures may have the incidental 
effect of shifting generation. In any event, in many instances, trading 
simply apportions the cost of controls between the sources engaged in 
the transaction, and does not result in generation shifting. To 
illustrate, assume that the EPA promulgates an emissions guideline that 
determines as the BSER the installation by a source of control 
equipment that captures 40 percent of its emissions of a pollutant. 
Assume further that a state allows two of its designated facilities of 
comparable size and emissions to engage in an emission trade, so that 
one source installs control equipment that captures 80 percent of its 
emissions, and the other one does not put on control equipment but 
purchases allowances from the first one that fund half the costs of the 
first one's control equipment. This type of emissions trade would not 
necessarily give rise to generation shifting.
---------------------------------------------------------------------------

    \193\ Id. at 2613 n.4.
    \194\ Comment Letter from Energy Strategy Coalition on 
``Adoption and Submittal of State Plans for Designated Facilities: 
Implementing Regulations Under Clean Air Act Section 111(d), EPA-HQ-
OAR-2021-0527-0088 at 6.
---------------------------------------------------------------------------

    For the reasons noted above, the EPA is rescinding the ACE Rule's 
interpretation that state plans may not include trading or averaging or 
other compliance flexibilities.
    v. The EPA's finalized interpretation of BSER. The EPA is also 
finalizing its proposal to rescind the ACE Rule's interpretation that 
CAA section 111, by its plain meaning, limits the BSER to at-the-source 
measures. The ACE Rule's interpretation is incorrect. In addition, as a 
practical matter, it could call into question many of the EPA's 
determinations in prior CAA section 111 rules that well-established 
control measures, including clean fuels and add-on control technology, 
qualified as the BSER. This is because many of these traditional 
measures are not entirely at-the-source controls, but also include 
outside-the-source components. West Virginia does not preclude the EPA 
from rescinding the ACE Rule interpretation because although the 
Supreme Court held that the CPP's generation-shifting BSER violated the 
major question doctrine, Court declined to address the ACE Rule's 
interpretation of CAA section 111.\195\
---------------------------------------------------------------------------

    \195\ 142 S.Ct. at 2615-16.
---------------------------------------------------------------------------

    To repeat for convenience the key requirements for determining the 
BSER under CAA section 111: each state must establish ``standards of 
performance for any existing source'' of certain types of air 
pollutants, under CAA section 111(d)(1); a ``standard of performance'' 
is defined as ``a standard for emissions of air pollutants which 
reflects the degree of emission limitation achievable through the 
application of the best system of emission reduction . . . adequately 
demonstrated, under CAA section 111(a)(1);'' and ``existing source'' is 
defined as a ``stationary source,'' which, in turn, is defined, in 
relevant part, as ``any building, structure, facility or 
installation,'' under CAA section 111(a)(6) and (a)(3).
    The ACE Rule interpreted CAA section 111 to limit, by its plain 
language, the type of ``system'' that the EPA may select as the BSER to 
control measures that can be applied at each source to reduce that 
source's emissions.\196\ Specifically, the ACE Rule argued that the 
requirements in CAA section 111(d)(1), (a)(3), and (a)(6) that each 
state establish a standard of performance ``for'' ``any existing 
source'' (in the singular), defined, in general, as any ``building . . 
. [or] facility,'' and the requirements in CAA section 111(a)(1) that 
the standard of performance reflect a degree of emission limitation 
that is ``achievable'' through the ``application'' of the BSER, by 
their terms, impose this limitation.\197\
---------------------------------------------------------------------------

    \196\ 84 FR 32523-24.
    \197\ Id. at 32556-57.
---------------------------------------------------------------------------

    Upon reconsideration, the EPA concludes that, contrary to the ACE 
Rule, CAA section 111(d) does not limit the EPA to at-the-source 
measures in determining the BSER. The CAA section

[[Page 80536]]

111 requirement that each state establish a standard of performance 
``for'' any existing ``building . . . [or] facility,''' means simply 
that the state must establish standards applicable to each regulated 
stationary source; and the requirement that the standard reflect a 
degree of emission limitation ``achievable'' through the 
``application'' of the BSER means that the source must be able to apply 
the system to meet the standard. None of these requirements by their 
plain language mandate that the BSER is limited to some measure that 
each source can apply to its own facility to reduce its own emissions 
in a specified amount. That the standards must be ``for'' a source does 
not mean that the control measures that form the basis for the standard 
are limited to measures that apply at the source or that all emission 
reductions from the control measures must occur at the source.
    The ACE Rule also argued that as a matter of grammar, the term 
``application,'' which is derived from the verb, ``to apply,'' requires 
an indirect object, and, further, that the phrase ``application of the 
best system of emission reduction'' has, as the unstated indirect 
object, an existing source. From this premise, the ACE Rule concluded 
that the phrase must be read to refer to the application of the best 
system of emission reduction at or to the existing source itself.\198\ 
But this premise is incorrect. As the D.C. Circuit explained in 
American Lung Ass'n, ``application'' is a noun, and ``the phrase 
`application of the best system of emission reduction' is what is 
called a nominalization, a `result of forming a noun or noun phrase 
from a clause or a verb.' '' \199\ The court further explained that 
``[g]rammar assigns direct or indirect objects only to verbs--not 
nouns. No objects are needed to grammatically complete the actual 
statutory phrase.'' \200\ In any event, the fact that any such indirect 
object is unstated itself contradicts the ACE Rule's conclusion that 
CAA section 111 by its plain language mandates that the BSER must be 
limited to at-the-source measures.\201\
---------------------------------------------------------------------------

    \198\ Id. at 32524.
    \199\ 985 F.3d at 948 (citations omitted).
    \200\ Id.
    \201\ The ACE Rule stated that the CAA provisions concerning the 
``best available control technology'' (BACT) provide a CAA 
structural argument that supports its interpretation that CAA 
section 111 limits BSER to at-the-source measures. CAA section 
165(a)(4) provides that construction and modification of major 
stationary sources of a pollutant are subject to BACT, as defined 
under CAA section 169(3), for each pollutant subject to regulation 
under the CAA. The definition of BACT provides, ``In no event shall 
application of [BACT] result in emissions of any pollutants which 
will exceed the emissions allowed by any applicable standard 
established pursuant to [CAA] section [111] or [112].'' The ACE Rule 
pointed to the EPA's reading of this sentence to mean that section 
111 standards of performance ``operate as a floor to BACT.'' The ACE 
Rule asserted that, under the definition of BACT, control measures 
are limited to at-the-source measures. The ACE Rule reasoned that 
section 111 standards of performance must, by operation of the 
structure of the CAA, also be interpreted to be limited to at-the-
source measures. 84 FR 32525. Upon further review, the EPA rejects 
this argument. The EPA considers whether CAA section 169(3) should 
be interpreted to limit BACT to at-the-source measures to be an open 
question, and is not addressing it at this time. Even if BACT were 
so limited, the ACE Rule did not demonstrate that any BACT 
requirement that a particular source would be subject to would be 
incompatible with any standard of performance that source would also 
be subject to. Section 169(3) by its plain language provides that 
the application of BACT may not result in exceedances of any 
applicable standard of performance.
    The ACE Rule also focused on statements in the CPP that it 
asserted conflated the terms ``application'' and implementation, as 
well as ``source'' and owner/operator; and that defined ``system'' 
broadly. The rule asserted that the CPP strained the interpretation 
of CAA section 111 in those ways to justify determining generation-
shifting as the BSER. 84 FR 32526-29. Regardless of whether those 
arguments have merit with respect to the generation-shifting, they 
are not relevant to the position that the EPA is taking in the 
present action that the ACE Rule erred in interpreting CAA section 
111 by its terms to limit the BSER to at-the-source measures. It 
should also be noted that the CPP's recognition that as a practical 
matter, it is the owner/operator who takes actions to apply control 
measures and assure that the source's emissions meet the standard is 
a matter of common sense and applies as well to all control 
measures, whether at the source or outside the source. The ACE Rule 
itself referred to the ``owner or operator'' as the entity that 
``must be able to achieve an applicable standard by applying the 
BSER . . . .'' 84 FR 32524.
---------------------------------------------------------------------------

    It should also be noted that CAA section 111(a)(1) provides that 
when the EPA determines the BSER, it must ``tak[e] into account'' 
``cost'' and ``any nonair quality health and environmental impact and 
energy requirements.'' As the ACE Rule itself recognized, the EPA may 
consider the application of these requirements on a ``sector-wide, 
region-wide or nationwide basis.'' \202\ As discussed below, the 
reference to ``nonair quality health and environmental impact'' may 
encompass to offsite impacts of control measures. Thus, these 
provisions contradict the ACE Rule's argument that CAA section 
111(d)(1) and (a), by its plain language, limits the BSER to at-the-
source measures. By the same token, the term ``achievable'' refers to 
the ``degree of emission limitation'' that must be ``reflect[ed]'' in 
the standards of performance ``through the application of the [BSER].'' 
This term does not, by its plain language, limit the BSER to at-the-
source measures.
---------------------------------------------------------------------------

    \202\ 84 FR 32534 n.152 (referring to application of ``energy 
requirements'').
---------------------------------------------------------------------------

    Importantly, it should be emphasized that the ACE Rule's 
interpretation that the provisions of CAA section 111(d)(1) and (a) by 
their plain language require that the EPA identify as the BSER control 
measures that apply at-the-source would also impose the same limit on 
the state, that is, limit the state to authorizing its sources to 
comply with their standards only through at-the-source measures. As a 
result, this interpretation would preclude the state from allowing its 
sources compliance flexibilities such as trading or averaging. In fact, 
the ACE Rule argued that states were limited in that manner. For the 
reasons noted above, limiting the states in that manner is contrary to 
the provisions of CAA section 111(d) and the framework of cooperative 
federalism that CAA section 111(d) establishes.
    The ACE Rule also argued that the legislative history of the 1970 
CAA Amendments confirms the rule's at-the-source interpretation for 
BSER.\203\ The rule read the legislative history to indicate that the 
House and Senate bills that led to the adoption of CAA section 111 
``contemplated only control measures that would lead to better design, 
construction, operation, and maintenance of an individual source. . . 
.'' \204\ The EPA disagrees with this interpretation of the legislative 
history. The ACE Rule itself acknowledged that the 1970 CAA Amendments 
legislative history also included broader language in describing the 
types of measures that were to provide the basis for the standards of 
performance.\205\ In addition, the ACE Rule went on to narrow its 
argument about legislative history to saying that the 1990 CAA 
Amendments made clear only that generation-shifting was precluded.\206\ 
Id. at 32526 n.62. Thus, the EPA finds that the legislative history 
cannot be read to confirm the interpretation that section 111(d) and 
(a)(1), by their plain language, limit the BSER to at-the-source 
measures.
---------------------------------------------------------------------------

    \203\ 84 FR 32525-26.
    \204\ Id. at 32526.
    \205\ Id. at 32526 n.61. The ACE Rule argued that the canon of 
ejusdem generis required that those broader terms be interpreted to 
denote at-the-source measures but ejusdem generis is an aid in 
statutory construction and should not be used to narrow the meaning 
of a statute beyond its intention. Karl N. Llwellyn, Remarks on the 
Theory of Appellate Decision and the Rules or Canons about how 
Statutes are to be Construed, 3 Vanderbilt L. Rev. 395, 405 & n.46 
(1950).
    \206\ Id. at 32526 n.61.
---------------------------------------------------------------------------

    There is another reason why the ACE Rule's interpretation is 
incorrect: it appears to be inconsistent with many EPA determinations 
in previous CAA section 111 rulemakings that certain control measures 
qualified as the BSER. This is because although those measures apply at 
the source and reduce

[[Page 80537]]

emissions at the source, they also have components that are outside the 
source. In West Virginia, the Supreme Court recognized that the EPA 
had, in prior rules, identified as the BSER these ```more traditional 
air pollution control measures.' ''\207\ The Court made this point as 
part of its reasoning that the CPP's generation-shifting BSER--which 
the Court stated differed from these traditional measures--raised a 
major question. The Court quoted the CPP as describing these 
traditional measures as ```efficiency improvements, fuel-switching,'' 
and `add-on controls.' '' \208\ The Court noted that these types of 
controls have several characteristics: they ``reduce pollution by 
causing the regulated source to operate more cleanly.'' \209\ They `` 
`allow[ ] regulated entities to produce as much of a particular good as 
they desire provided that they do so through an appropriately clean (or 
low-emitting) process.' '' '\210\ They are ``technology-based . . . 
[and] focuse[d] on improving the emissions performance of individual 
sources.'' \211\
---------------------------------------------------------------------------

    \207\ 142 S.Ct.at 2611 (citing 80 FR 64662, 64784 (Oct. 23, 
2015)).
    \208\ Id. (citing 80 FR 64784).
    \209\ 142 S.Ct. at 2610.
    \210\ Id. (quoting 80 FR 64738).
    \211\ Id. at 2611.
---------------------------------------------------------------------------

    However, many of these traditional controls also have components 
that are outside the source. One example includes what the Court, 
quoting the CPP, identified as ``fuel-switching.'' \212\ Fuel-switching 
entails the use of lower-emitting fuels. These include fuels that have 
been cleaned, or processed, to reduce their level of pollutants,\213\ 
such as coal or oil that has been desulfurized. Desulfurization reduces 
the amount of sulfur in the fuel, which means that the fuel can be 
combusted with fewer SO2 emissions. Importantly, the process 
of desulfurization typically occurs off-site and is undertaken by third 
parties. Congress itself recognized this in the 1977 CAA Amendments. 
Specifically, Congress revised CAA section 111(a)(1) to identify the 
basis for standards of performance for new fossil fuel-fired stationary 
sources as a ``technological system of continuous emission reduction,'' 
including ``precombustion cleaning or treatment of fuels.'' \214\ The 
1977 House Committee report stated that fuel cleaning includes ``oil 
desulfurization at the refinery.'' \215\ The report added that fuel 
cleaning includes ``various coal-cleaning technologies,'' which 
generally are also conducted off-site by third parties.\216\ As noted 
above, in the 1990 CAA Amendments, Congress eliminated many of the 
restrictions and other provisions added in the 1977 CAA Amendments by 
largely reinstating the 1970 CAA Amendments' definition of ``standard 
of performance.'' Nevertheless, there is no indication that in doing 
so, Congress intended to preclude the EPA from considering fuel 
cleaning off-site by third parties. In fact, the EPA's regulations 
promulgated after the 1990 CAA Amendments continue to impose standards 
of performance that are based on coal cleaning off-site by third 
parties.\217\
---------------------------------------------------------------------------

    \212\ Id.
    \213\ EPA considered fuel cleaning to be within the scope of the 
best system of emission reduction beginning immediately after the 
adoption of the 1970 CAA Amendments. See U.S. EPA, Background 
Information for Proposed New-Source Performance Standards: Steam 
Generators, Incinerators, Portland Cement Plants, Nitric Acid 
Plants, Sulfuric Acid Plants, Office of Air Programs Tech. Rep. No. 
APTD-0711, p. 7 (Aug. 1971) (indicating the ``desirability of 
setting sulfur dioxide standards that would allow the use of low-
sulfur fuels as well as fuel cleaning, stack-gas cleaning, and 
equipment modifications'' (emphasis added)).
    \214\ 1977 CAA Amendments, section 109, 91 Stat. 700; see also 
CAA section 111(a)(7).
    \215\ H.R. Rep. No. 95-294 (May 12, 1977), 1977 CAA Legis. Hist. 
at 2655 (emphasis added).
    \216\ Id. EPA recognized in a regulatory analysis of new source 
performance standards for industrial-commercial-institutional steam 
generating units that the technology ``requires too much space and 
is too expensive to be employed at individual industrial-commercial-
institutional steam generating units.'' U.S. EPA, Summary of 
Regulatory Analysis for New Source Performance Standards: 
Industrial-Commercial-lnstitutional Steam Generating Units of 
Greater than 100 Million Btu/hrHeat Input, EPA-450/3-86-005, p. 4-4 
(June 1986).
    \217\ 40 CFR 60.49b(n)(4); see also Amendments to New Source 
Performance Standards (NSPS) for Electric Utility Steam Generating 
Units and Industrial-Commercial-Institutional Steam Generating 
Units; Final Rule, 72 FR 32742 (June 13, 2007).
---------------------------------------------------------------------------

    A second example includes what the Court, again quoting the CPP, 
identified as ``add-on controls.'' \218\ These controls include air 
pollution control devices that are installed at the unit. They 
routinely operate by removing air pollutants from a unit's emission 
stream and capturing them as a liquid or solid. For example, a baghouse 
is an add-on control device that captures particulate matter by 
trapping particles as a dust, which must then be disposed of.\219\ 
Another add-on control device, flue-gas desulfurization, ``scrubs'' 
acid gases like sulfur dioxide from emissions using a chemical sorbent 
that reacts with the pollutant to generate a liquid slurry (wet 
scrubbing) or solid residue (dry scrubbing). These captured pollutants 
must then be disposed as solid wastes, discharged as wastewater, or 
otherwise managed or reused.\220\ The same is true for carbon capture 
and sequestration (CCS): the carbon capture control device scrubs 
CO2 from the flue gas stream using a solvent; and the 
CO2 must then be stored underground.\221\ Downstream 
management of captured pollutants is thus a commonplace feature of CAA 
section 111 standards.\222\ Downstream management of captured 
pollutants is thus a commonplace feature of CAA section 111 
standards.\223\
---------------------------------------------------------------------------

    \218\ 142 S.Ct. at 2611.
    \219\ See Sierra Club v. Costle, 657 F.2d 298, 375 (D.C. Cir. 
1981).
    \220\ See id. at 323-24 n.69; see also 80 FR 21303, 21340 (April 
17, 2015) (governing off-site disposal of solid wastes captured by 
air pollution controls at steam units).
    \221\ 80 FR 64549, 64555 (describing CCS and comparing CCS 
pollutant disposition to particulate or wet scrubber pollutant 
disposition).
    \222\ See, e.g., 80 FR 64582-90 (requiring that an EGU that 
captures CO2 assure that it is transferred to an entity 
that will dispose of it appropriately; generally describing 
oversight of CO2 storage; detailing Department of 
Transportation pipeline regulations; detailing requirements for 
monitoring, reporting, and verification plans; detailing injection 
well requirements under the Safe Drinking Water Act; and detailing 
how existing regulations prevent, monitor, and address potential 
leakage); 75 FR 54970, 55022-23 (Sept. 9, 2010) (disposal of 
wastewater and solid waste from CAA section 111 standard for 
Portland cement plants); 54 FR 34008, 34015 (Aug. 17, 1989) (waste 
disposal impacts of standard of performance for sulfur oxide 
emissions for fluid catalytic cracking unit regenerators).
    \223\ See 80 FR 64549, 64555 (describing CCS and comparing CCS 
pollutant disposition to particulate or wet scrubber pollutant 
disposition).
---------------------------------------------------------------------------

    Indeed, CAA section 111(a)(1) by its terms recognizes that 
``system[s] of emission reduction'' may entail off-site disposition of 
pollutants. The provision states that the EPA must consider ``nonair 
quality health and environmental impact'' when determining the BSER. 
Congress adopted this phrase in the 1977 CAA Amendments.\224\ As the 
legislative history stated, Congress added this phrase so that 
``environmental impacts would be required to be considered in 
determining best technology which has been adequately demonstrated.'' 
\225\ In making this addition, Congress codified the D.C. Circuit's 
holding in Essex Chem. Corp. v. Ruckelshaus, 486 F.2d 427, 438-39 (D.C. 
Cir. 1973), cert. denied, 416 U.S. 969 (1974).\226\ In Essex Chem. 
Corp., the D.C. Circuit required that EPA ``take into account counter-
productive environmental effects'' when determining whether a control 
measure qualifies as the BSER, including ``disposal problems'' related 
to the control measure's captured pollutants. The Court remanded the 
NSPS at issue because there was no evidence that the EPA had considered 
``the significant land or water pollution potential

[[Page 80538]]

resulting from disposal of the [scrubber system's] liquid purge 
byproduct.'' \227\ That the ACE Rule's interpretation that CAA section 
111 limits the BSER to at-the-source measures may be inconsistent with 
the EPA's prior determinations that traditional control measures like 
clean fuels and add-on controls qualified as the BSER provides another 
reason to reject that interpretation.
---------------------------------------------------------------------------

    \224\ Pub. L. 95-95, section 109(c)(1)(A) (Aug. 7, 1977), 91 
Stat. 699-700.
    \225\ H.R. Rep. No. 95-294 at 190 (May 12, 1977).
    \226\ Id.
    \227\ Id. See Portland Cement Ass'n v. Ruckelshaus, 486 F.2d 
375, 385 n.42 (D.C. Cir. 1973) (``The standard of the ``best 
system'' is comprehensive, and we cannot imagine that Congress 
intended that `best' could apply to a system which did more damage 
to water than it prevented to air.'').
---------------------------------------------------------------------------

    It should be noted that many of the reasons noted above are 
comparable to the reasoning by the D.C. Circuit to support its decision 
in ALA that the ACE Rule was incorrect in interpreting CAA section 111 
to restrict the BSER to at-the-source measures.\228\ The EPA agrees 
with the D.C. Circuit's reasoning.
---------------------------------------------------------------------------

    \228\ 985 F.3d 914, 955-41 (D.C. Cir. 2021).
---------------------------------------------------------------------------

    In West Virginia, the Supreme Court held that the CPP's generation-
shifting BSER violated the major question doctrine, and the Court 
vacated ALA on the basis of that holding.\229\ However, the Court 
declined to address the ACE Rule's interpretation of CAA section 
111.\230\ Thus, its opinion does not cast doubt on the EPA's reasons 
for rejecting the ACE Rule's interpretation, as noted above and in ALA. 
Several commenters argued that West Virginia indicates that control 
measures that the commenters considered comparable to the generation-
shifting BSER of the CPP, including trading programs and other measures 
that controlled designated facilities in the aggregate, were also 
precluded from inclusion as the BSER under the major question 
doctrine.\231\ Other commenters disagreed, arguing that West Virginia 
identifies distinctions among those programs, so that the major 
question doctrine would not necessarily apply.\232\ However, as noted 
in the proposal, in this action, the EPA is not addressing what types 
of controls, in addition to the generation-shifting BSER of the CPP, 
would be precluded under CAA section 111 by the major question 
doctrine. Instead, the EPA will evaluate particular controls against 
the doctrine, as appropriate, when the EPA considers those controls in 
future rulemakings under CAA section 111.
---------------------------------------------------------------------------

    \229\ 142 S.Ct. at 2610, 2614, 2615-16.
    \230\ Id. at 2615-16.
    \231\ API Comment Letter on ``Adoption and Submittal of State 
Plans for Designated Facilities; Implementing Regulations Under 
Clean Air Act Section 111(d)'' (``Subpart Ba''), EPA-HQ-OAR-2021-
0527-0074 at 8; Lignite Energy Council Comment Letter on Subpart Ba, 
EPA-HQ-OAR-2021-0527-0100 at 8-9.
    \232\ Energy Strategy Coalition Comment Letter on Subpart Ba, 
EPA-HQ-OAR-2021-0527-0088 at 6 (noting that West Virginia 
distinguished the trading program in the Clean Air Mercury Rule, 
which was based on technological controls, from the trading program 
in the CPP).
---------------------------------------------------------------------------

2. Minor Amendments or Clarifications
    The EPA proposed to amend the regulatory text in subpart Ba to 
address several editorial and other minor clarifications and is 
finalizing the amendments as described below. Except as noted 
specifically below, commenters supported these revisions to the 
regulatory text.
    a. The EPA is finalizing amendments to the applicability provision 
for subpart Ba under 40 CFR 60.20a, with slight revision from as 
proposed. As discussed in section II.B. of this preamble, the revised 
applicability provision clarifies that the provisions of subpart Ba are 
applicable to an EG published after July 8, 2019. The EPA is finalizing 
the proposed removal of text that included ``if implementation of such 
final guideline is ongoing'' because there are no EGs the 
implementation of which is ongoing; \233\ thus, leaving this language 
in the regulation would be needlessly confusing. Emission guidelines 
issued on and prior to July 8, 2019, and pursuant to CAA section 129 
are subject to the provisions of subpart B. Also, in response to 
comment that the term ``final emission guideline'' is unclear, the EPA 
is adding the term ``in the Federal Register'' to 40 CFR 60.20a(a) to 
clarify the publication in the Federal Register determines the 
applicability date. Further clarification of the term ``final emission 
guideline'' is available in 40 CFR 60.22a(a). A commenter also noted 
that the proposed rule text deleted all references to ``subpart C of 
this part'' and removing this language means that it would apply to all 
EGs in 40 CFR part 60 (that are published after July 8, 2019), 
including those for incinerators addressed by CAA section 129. This was 
not the EPA's intent. Therefore, as noted in section III.G.2.b. of this 
preamble, the EPA is amending the definition of EG within subpart Ba to 
clarify that subpart Ba does not apply to EGs promulgated under CAA 
section 129.
---------------------------------------------------------------------------

    \233\ The Municipal Solid Waste Landfills EG, which is currently 
being implemented, has its own applicability provisions and is 
subject to subpart B.
---------------------------------------------------------------------------

    b. The EPA is finalizing revisions to 40 CFR 60.21a(e), 60.22a(c), 
and 60.24a(c) and (f)(1) and (2), largely as proposed, at 40 CFR 
60.21a(e), 60.22a(c), and 60.24a(c) and (i)(1) and (2) respectively 
(differences in numbering are due to provisions changing location in 
the final regulations relative to proposal). These revisions delete 
``subpart C'' from these provisions because EGs can be codified in 
other subparts of this part and not only in subpart C of this part. In 
response to a comment requesting clarification, 40 CFR 60.21a(e) is 
also amended clarify that the definition of emission guidelines for 
purposes of subpart Ba excludes guidelines promulgated pursuant to CAA 
section 129. As discussed above, EGs under CAA section 129 are subject 
to the provisions of subpart B.
    c. The EPA is finalizing as proposed an editorial amendment to 40 
CFR part 60, subpart A, at Sec.  60.1(a) to add a reference to subpart 
Ba. The applicability provision in 40 CFR 60.1(a) states that 
``[e]xcept as provided in subparts B and C, the provisions of this part 
apply to the owner or operator of any stationary source which contains 
an affected facility, the construction or modification of which is 
commenced after the date of publication in this part of any standard 
(or, if earlier, the date of publication of any proposed standard) 
applicable to that facility.'' We are amending this provision to 
include reference to subpart Ba in addition to subparts B and C.
    d. A minor editorial correction at 40 CFR 60.22a(b)(3) amends the 
term ``nonair quality health environmental effects'' to ``nonair 
quality health and environmental effects''.
3. Submission of Emissions Data and Related Information
    The EPA is finalizing as proposed amendments to 40 CFR 60.25a(a) 
that delete reference to 40 CFR part 60, appendix D, because the system 
specified for information submittal by the appendix is no longer in use 
and clarify that the applicable EG will specify the system for 
submission of the inventory of designated facilities, including 
emission data for the designated pollutants and any additional required 
information related to emissions. The EPA also proposed to delete the 
term ``related to emissions'' in 40 CFR 60.25a(a). A commenter noted as 
proposed this deletion caused the provision to be too vague. The EPA 
agrees that the term ``related to emissions'' should be retained to 
maintain the original and proper context of this provision. The term is 
retained by this final action.
4. State Permit and Enforcement Authority
    Questions have previously arisen as to whether states may establish 
standards of performance and other plan requirements as part of state 
permits

[[Page 80539]]

and administrative orders. The EPA is confirming with this final action 
that subpart Ba allows for standards of performance and other state 
plan requirements to be established as part of state permits and 
administrative orders, which then must be incorporated into the state 
plan. See 40 CFR 60.27a(g)(2)(ii).
    However, the EPA notes that the permit or administrative order 
alone may not be sufficient to meet the requirements of an EG or the 
implementing regulations, including the completeness criteria under 40 
CFR 60.27a(g). For instance, a plan submittal must include supporting 
material demonstrating the state's legal authority to implement and 
enforce each component of its plan, including the standards of 
performance, 40 CFR 60.27a(g)(2)(iii), as well as a demonstration that 
each emission standard is quantifiable, non-duplicative, permanent, 
verifiable, and enforceable. Id. at Sec.  60.27a(a)(2)(vi). In 
addition, the specific EGs may also require demonstrations that may not 
be satisfied by terms of a permit or administrative order. To the 
extent that these and other requirements are not met by the terms of 
the incorporated permits and administrative orders, states will need to 
include materials in a state plan submission demonstrating how the plan 
meets those requirements. If a state does choose to use permits or 
administrative orders to establish standards of performance, it needs 
to demonstrate that it has the legal authority to do so. These 
implementing regulations do not themselves provide any independent or 
additional authority to issue permits and administrative orders under 
states' EPA approved title I and title V permitting programs.

IV. Summary of Cost, Environmental, and Economic Impacts

    In amending general implementing regulations, this final action 
does not independently impose any requirements and therefore does not 
directly incur any costs or benefits. However, the amendments finalized 
in this action can impact the costs and benefits of future EGs subject 
to subpart Ba. The potential impacts of these amendments as reflected 
in an EG will vary greatly depending on the source category, number and 
location of designated facilities, and the designated pollutant and 
potential controls addressed by the EG. Of note, the EPA may propose to 
supersede these general provisions in an EG as needed and with 
appropriate justification. Individual EGs are subject to notice and 
comment rulemaking, providing the opportunity for stakeholders, 
including the public, to consider the impacts of implementing or 
superseding these general implementing regulations in the course of 
those rulemaking actions.
    As described in detail in section III.A. of this preamble, the EPA 
is finalizing amendments to subpart Ba to replace timelines vacated by 
the D.C. Circuit in ALA \234\ and to improve and update other 
provisions within subpart Ba. This section considers general impacts 
that could result from the amendments finalized in this action as 
adopted by an EG.
---------------------------------------------------------------------------

    \234\ Am. Lung Ass'n v. EPA, 985 F.3d 914, 991 (D.C. Cir. 2021).
---------------------------------------------------------------------------

    As discussed in section III.A. of this preamble, the EPA does not 
interpret the D.C. Circuit's direction to require the Agency to 
quantitatively evaluate the impacts of potential subpart Ba framework 
timelines, but rather to consider the balance between the public health 
and welfare benefits resulting from appropriate and reasonable 
deadlines for the implementation of EGs and the time needed for the 
technical, administrative, and legislative actions needed to develop 
and adopt approvable state or Federal plans. The EPA expects that the 
amendments to subpart Ba finalized in this action will improve the 
implementation of EGs under CAA section 111(d). In particular, the EPA 
expects that the timelines finalized both appropriately accommodate 
state and EPA processes to develop and evaluate plans to effectuate an 
EG and are consistent with the objective of CAA section 111(d) to 
ensure that designated facilities expeditiously control emissions of 
pollutants that the EPA has determined may be reasonably anticipated to 
endanger public health or welfare.
    While the EPA initially proposed a 15-month deadline for state plan 
submissions following the promulgation of an EG (87 FR 79176, Dec. 23, 
2022), most commenters, including states and state organizations, 
indicated that 15 months could not accommodate the technical, 
administrative, and legal steps necessary to develop and adopt an 
approvable state plan. Based on the comments and additional information 
received, the EPA is finalizing 18 months for state plan submissions 
after promulgation of a final EG, and finds that the additional time, 
compared with the 9 months provided in subpart B, will better 
accommodate states' processes to develop and adopt approvable plans and 
will most efficiently effectuate the applicable EG. Under an 18-month 
state plan submission timeframe, the costs of developing a state plan 
under an applicable EG subject to subpart Ba, compared with the 9 
months provided by subpart B, may be spread over 9 additional months. 
With this state plan submittal timeline, the EPA is providing states 
sufficient time to develop approvable implementation plans for their 
designated facilities that adequately address public health and 
environmental objectives. A timeline that is insufficient for states to 
conduct, inter alia, the appropriate technical analysis and public 
engagement may preclude them from timely adopting and submitting 
approvable state plans, which could ultimately delay the implementation 
of emission reductions. In addition, a successful submittal of 
approvable state plans will avoid an attendant expenditure of Federal 
resources associated with the development of a Federal plan.
    After receiving a state plan, the EPA first must determine if the 
plan is complete. The EPA is finalizing amendments to its determination 
of completeness so the timeframe for such determination is streamlined 
from six months to 60 days from receipt of the state plan submission 
(see section III.A.2. of this preamble). If the EPA determines a state 
plan submission is complete, it then evaluates the plan to determine 
whether it satisfies the applicable requirements. The Agency proposes 
an action (e.g., plan approval or plan disapproval) and then finalizes 
its action pursuant to a notice-and-comment rulemaking process. As 
described in detail in sections III.A.3. and III.A.4. of this preamble, 
the EPA is finalizing a 12-month period for the EPA to take final 
action on a state plan after a submission is found to be complete. The 
EPA is also finalizing a 12-month timeline for the EPA to promulgate a 
Federal plan, which runs from either the state plan deadline if a state 
has failed to submit a state plan, 60 days following the state plan 
deadline if a state has submitted a plan by the deadline and the EPA 
determines it is incomplete, or from the date the EPA finalizes 
disapproval of a state plan submission. As described in detail in 
section III. of this preamble, because these timeframes provide for the 
minimum time reasonably necessary for the EPA to accomplish propose and 
finalize a Federal plan, the EPA expects these timeframes will minimize 
the impacts on public health and welfare to the extent possible while 
ensuring that an EG is expeditiously implemented.
    As described in detail in section III.A.5. of this preamble, the 
EPA is finalizing a requirement that state plans include IoPs if the 
plan requires final

[[Page 80540]]

compliance with standards of performance later than 20 months after the 
plan submission deadline. The compliance schedule, as defined in 
subpart Ba (40 CFR 60.21a(g)) is a legally enforceable schedule 
specifying a date or dates by which a source or category of sources 
must comply with specific standards of performance contained in a plan. 
If final compliance for a source to meet their standards of performance 
is more than 20 months after the state plan submittal deadline, the 
plan must include IoPs, which are defined steps to achieve compliance 
(e.g., submittal of a control plan, awarding of contracts for emission 
control systems or process modification, etc.). This 20 month timeline 
is the trigger for when IoPs must be included in a state plan. An EG 
will specify what the IoPs are and associated compliance schedules. The 
EPA considers this slightly longer timeline than is required under 
subpart B reasonable given that the EPA is also, in this action, 
extending the timelines for state plan submission under subpart Ba. The 
EPA notes that IoPs do not, on their own, govern how expeditiously 
emission reductions are achieved: this is dictated by the final 
compliance date, which is established in an individual EG. 
Additionally, any specific requirements associated with IoPs, including 
extended or truncated timelines, would be included in the EG, as these 
are dependent on the source type, pollutant, and control strategy 
addressed.
    The EPA is also finalizing amending subpart Ba to enhance 
requirements for reasonable notice and opportunity for public 
participation. In particular, the EPA is requiring that states, as part 
of the state plan development or revision process, provide 
documentation that they have conducted meaningful engagement with a 
broad range of pertinent stakeholders and/or their representatives. 
Pertinent stakeholders include communities most affected by and 
vulnerable to the impacts of the plan or plan revision (see section 
III.C. of this preamble).
    Overall, the EPA expects the amendments being finalized in this 
action will benefit the states in the development of approvable state 
plans. The EPA expects that the amendments associated with meaningful 
engagement with pertinent stakeholders will potentially increase the 
amount of information the states can use in designing state plans, 
which may increase both the level of resources states will need to 
employ in the development of an approvable plan, as well as the 
resulting health and welfare benefits of the plan. In addition to 
health and welfare benefits, there are also administrative benefits of 
engaging with stakeholders and receiving pertinent information as a 
state plan is being developed. Such engagement may improve the record 
for the state's plan and reduce the amount of comments received when 
the state plan is proposed to the public, which would reduce the amount 
of effort employed after proposal to address issues raised by the 
public and stakeholders.
    There is variation and uncertainty in determining the magnitude of 
impacts, both to states and the public, resulting from amendments 
associated with meaningful engagement. First, the EPA notes that the 
meaningful engagement provisions being finalized in this action are 
largely procedural in nature and do not prescribe any particular set of 
actions or activities that states must undertake. The potential costs 
and benefits will therefore be determined in significant part by 
choices that are within states' discretion. Second, the impacts of 
conducting meaningful engagement will be highly dependent on the number 
and location of designated facilities addressed by an EG, as well as on 
the type of health or environmental impacts of the associated 
emissions. If stakeholder and public involvement pursuant to the 
meaningful engagement provisions does not generate a large number of 
specific and unique comments, data, or other considerations, then the 
level of effort states will employ to review them will be lower in 
comparison to when meaningful engagement comments are voluminous. It 
might also be expected that less input and fewer comments might, in 
certain cases, have an adverse impact on the ability of a state plan to 
fulfill its health and welfare objectives.
    To the extent that states already conduct significant engagement 
with pertinent stakeholders, the meaningful engagement amendments will 
most likely not result in additional costs. Conversely, states that do 
not have engagement procedures already in place may be required to 
increase their level of effort to engage with pertinent stakeholders. 
The burden and benefits of meaningful engagement for the pertinent 
stakeholders will also be highly dependent on the EG and associated 
variables such as, but not limited to, the geographical distribution of 
the facilities and communities impacted, available modes of 
participation for those areas, the pollutants addressed, and the range 
of options available to the state and facilities for meeting the EG 
standards. The burden and benefits to pertinent stakeholders may be 
difficult to quantify, but overall their engagement will be voluntary 
and is anticipated to result in feedback that may improve the resulting 
health and welfare benefits of the state plan as perceived and 
experienced, particularly by those in communities most affected by and 
vulnerable to the impacts of the plan.
    The EPA is also finalizing revisions to the RULOF provisions in 
subpart Ba. The amendments included in this final action are intended 
to provide clarity for states to ensure that less-stringent standards 
of performance for particular designated facilities are consistent with 
the statutory requirements, as well as a consistent framework for EPA 
to evaluate such standards across EGs and states (see section III.E. of 
this preamble).
    The magnitude of impacts, both to states and the public, resulting 
from the final RULOF amendments will vary depending on the particular 
EG to which the final provisions would apply. As explained in section 
III.E.2. of this preamble, the EPA believes Congress intended RULOF as 
a mechanism for states to apply a less-stringent standard of 
performance in the unusual circumstances in which the degree of 
emission limitation determined by the EPA is not reasonable for a 
particular designated facility. Additionally, states are not required 
to invoke the RULOF provision in any particular instance and may choose 
not to do so, even if a particular designated facility's circumstances 
meet the threshold specified in the regulations. If a state does not 
invoke RULOF in their state plan, then the amendments will not result 
in any additional costs. If a state does invoke RULOF in their state 
plan, then the amendments could, in certain circumstances, result in an 
increased level of effort to develop standards of performance for 
certain sources. As such, the RULOF amendments could potentially 
increase the level of resources states will need to employ in the 
development of an approvable plan. However, because the amendments 
clarify is required in order for a less-stringent standard pursuant to 
RULOF to satisfy the statutory requirements, the amendments reduce the 
uncertainty of states and designated facilities in the development of 
such standards. This in turn could result in a decrease in the amount 
of time that a state that wished to invoke RULOF would need, relative 
to a situation where the requirements were less defined, by avoiding 
significant back and forth with the EPA and the sources in the state 
during state plan development. Overall, the EPA expects the RULOF 
amendments will benefit the states in the development of

[[Page 80541]]

approvable state plans and therefore result in benefits to public 
health and welfare.
    Finally, the EPA expects that the requirements for electronic 
submittal and that the availability of the optional regulatory 
mechanisms being finalized in this action will improve flexibility and 
efficiency in the call for and submission, review, approval, and 
implementation of state plans, and thus will overall result in benefits 
to the states, the EPA, designated facilities, and public health and 
welfare. In addition, the EPA expects the requirements for electronic 
submittal will increase the ease and efficiency of data submittal and 
data accessibility and benefit the states and the EPA. Electronic 
submittal will also improve the Agency's efficiency and effectiveness 
in the receipt and review of state plans.
    The EPA expects that the overall impacts of the implementation of 
the amendments to subpart Ba finalized in this action will improve the 
implementation of EGs under CAA section 111(d).

V. Statutory and Executive Order Reviews

    Additional information about these Statutory 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; Executive 
Order 13563: Improving Regulation and Regulatory Review; and Executive 
Order 14094: Modernizing Regulatory Review

    This action is a ``significant regulatory action'' as defined in 
Executive Order 12866, as amended by Executive Order 14094. 
Accordingly, the EPA submitted this action to the Office of Management 
and Budget (OMB) for Executive Order 12866 review. Documentation of any 
changes made in response to the Executive Order 12866 review is 
available in the docket.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the Paperwork Reduction Act. The requirements in subpart Ba do not 
themselves require any reporting and recordkeeping activities, and no 
Information Collection Request (ICR) was submitted in connection with 
the original promulgation of subpart Ba or the amendments we are 
finalizing at this time. Any recordkeeping and reporting requirements 
are imposed only through the incorporation of specific elements of 
subpart Ba in the individual emission guidelines, which have their own 
ICRs.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities. This final rule will 
not impose any requirements on small entities. Specifically, this 
action addresses processes related to state plans for implementation of 
EGs established under CAA section 111(d).

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or 
more as described in UMRA, 2 U.S.C. 1531-1538, and does not 
significantly or uniquely affect small governments. This final action 
does not contain a Federal mandate that may result in expenditures of 
$100 million or more for state, local, and Tribal governments, in the 
aggregate or the private sector in any 1 year.
    This final action is also not subject to the requirements of 
section 203 of UMRA because, as described in 2 U.S.C. 1531-38, it 
contains no regulatory requirements that might significantly or 
uniquely affect small governments. This action imposes no enforceable 
duty on any local, or Tribal governments or the private sector. 
However, this action imposes enforceable duties on states. This action 
does not meaningfully require additional mandates on states beyond what 
is already required of them and will not impose a burden in excess of 
$100 million.

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. The EPA 
believes, however, that this action may be of significant interest to 
state governments.
    Subpart Ba requirements apply to states in the development and 
submittal of state plans pursuant to emission guidelines promulgated 
under CAA section 111(d) after July 8, 2019, to the extent that an EG 
does not supersede the requirements of subpart Ba. This action 
finalizes amendments to certain requirements for development, 
submission, and approval processes of state plans under CAA section 
111(d). In particular, the amendments associated with state plan 
submission deadlines, RULOF provisions, meaningful engagement, and 
regulatory mechanisms may be of significant interest to state 
governments. In section IV of this preamble, the EPA summarizes the 
potential cost, environmental, and economic impacts of the 
implementation (through individual emission guidelines) of the 
amendments to subpart Ba being finalized in this action. Overall, the 
EPA expects these amendments will benefit the states in the development 
of approvable state plans.
    The EPA notes that notice and comment procedures required for the 
promulgation of individual EGs will provide opportunity for states to 
address issues related to federalism based on specific application of 
subpart Ba requirements to that particular EG.

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

    This action does not have Tribal implications as specified in 
Executive Order 13175. It would not impose substantial direct 
compliance costs on Tribal governments that have designated facilities 
located in their area of Indian country. Tribes are not required to 
develop plans to implement the guidelines under CAA section 111(d) for 
designated facilities. A tribe with an approved TAS under TAR for CAA 
111(d) is not required to resubmit TAS approval to implement an EG 
subject to subpart Ba. This action also will not have substantial 
direct costs or impacts 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.

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

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive order. This action is not subject to 
Executive Order 13045 because it does not concern an environmental 
health risk or safety risk.

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 will 
not have a significant adverse effect on the supply, distribution or 
use of energy. Specifically, this action addresses the

[[Page 80542]]

submission and adoption of state plans for implementation of EGs 
established under CAA section 111(d).

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

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

    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 (people of color and/or indigenous 
peoples) and low-income populations.
    The EPA believes that it is not practicable to assess whether the 
human health or environmental conditions that exist prior to this 
action result in disproportionate and adverse effects on people of 
color, low-income populations and/or indigenous peoples. The 40 CFR 
part 60, subpart Ba, provisions are the implementing regulations for 
states to plan in response to individual EGs, and these individual EGs 
are applicable to specific pollutants from specified categories of 
existing sources. It is not possible to identify or assess human health 
and environmental conditions that will be impacted by this rule because 
this rule does not address a particular set of sources or a particular 
pollutant. This action is revising the implementing regulations and 
does not directly impact environmental justice communities or result in 
new disproportionate and adverse effects.
    The EPA identified and addressed environmental justice concerns by 
specifying new requirements for meaningful engagement with pertinent 
stakeholders, which includes communities most affected by and/or 
vulnerable to the impacts of a state plan.
    The information supporting this Executive order review is contained 
in section III.C. and section III.E.3.f. of this action.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 60

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

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

PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES

0
1. The authority citation for part 60 continues to read as follows:

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


0
2. Amend Sec.  60.1 by revising paragraph (a) to read as follows:


Sec.  60.1  Applicability.

    (a) Except as provided in subparts B, Ba, and C of this part, the 
provisions of this part apply to the owner or operator of any 
stationary source which contains an affected facility, the construction 
or modification of which is commenced after the date of publication in 
this part of any standard (or, if earlier, the date of publication of 
any proposed standard) applicable to that facility.
* * * * *


0
3. Amend Sec.  60.20a by revising paragraph (a) introductory text to 
read as follows:


Sec.  60.20a  Applicability.

    (a) The provisions of this subpart apply upon publication of a 
final emission guideline under Sec.  60.22a(a) if the guideline is 
published in the Federal Register after July 8, 2019.
* * * * *

0
4. Amend Sec.  60.21a by:
0
a. Revising paragraphs (e) and (f); and
0
b. Adding paragraphs (k) and (l).
    The revisions and additions read as follows:


Sec.  60.21a  Definitions.

* * * * *
    (e) Emission guideline means a guideline set forth in this part, 
with the exception of guidelines set forth pursuant to section 129 of 
the Clean Air Act, or in a final guideline document published under 
Sec.  60.22a(a), which reflects the degree of emission limitation 
achievable through the application of the best system of emission 
reduction which (taking into account the cost of achieving such 
reduction and any non-air quality health and environmental impact and 
energy requirements) the Administrator has determined has been 
adequately demonstrated for designated facilities.
    (f) Standard of performance means a standard for emissions of air 
pollutants which reflects the degree of emission limitation achievable 
through the application of the best system of emission reduction which 
(taking into account the cost of achieving such reduction and any 
nonair quality health and environmental impact and energy requirements) 
the Administrator determines has been adequately demonstrated, 
including a legally enforceable regulation setting forth an allowable 
rate, quantity, or concentration of emissions into the atmosphere, or 
prescribing a design, equipment, work practice, or operational 
standard, or combination thereof.
* * * * *
    (k) Meaningful engagement means the timely engagement with 
pertinent stakeholders and/or their representatives in the plan 
development or plan revision process. Such engagement should not be 
disproportionate in favor of certain stakeholders and should be 
informed by available best practices.
    (l) Pertinent stakeholders include, but are not limited to, 
industry, small businesses, and communities most affected by and/or 
vulnerable to the impacts of the plan or plan revision.


0
5. Amend Sec.  60.22a by revising paragraphs (b)(3) and (c) to read as 
follows:


Sec.  60.22a  Publication of emission guidelines.

* * * * *
    (b) * * *
    (3) Information on the degree of emission limitation which is 
achievable with each system, together with information on the costs, 
nonair quality health and environmental effects, and energy 
requirements of applying each system to designated facilities.
* * * * *
    (c) The emission guidelines and compliance times referred to in 
paragraph (b)(5) of this section will be proposed for comment upon 
publication of the draft guideline document, and after consideration of 
comments will be promulgated in this part with such modifications as 
may be appropriate.


0
6. Amend Sec.  60.23a by:
0
a. Revising paragraph (a)(1);
0
b. Adding paragraph (a)(3);
0
c. Revising paragraph (b); and
0
d. Adding paragraph (i).
    The revisions and additions read as follows:

[[Page 80543]]

Sec.  60.23a  Adoption and submittal of State plans; public hearings.

    (a)(1) Unless otherwise specified in the applicable subpart in this 
part, within eighteen months after publication in the Federal Register 
of a final emission guideline under Sec.  60.22a(a), each State shall 
adopt and submit to the Administrator a plan for the control of the 
designated pollutant to which the emission guideline applies. The 
submission of such plan shall be made in electronic format according to 
paragraph (a)(3) of this section or as specified in an applicable 
emission guideline.
* * * * *
    (3) States must submit to the Administrator any plan or plan 
revision using the State Planning Electronic Collaboration System 
(SPeCS), which can be accessed through the EPA's Central Data Exchange 
(CDX) (https://cdx.epa.gov/) or through an analogous electronic 
reporting tool provided by the EPA for the submission of any plan 
required by this subpart. Do not use SPeCS to submit confidential 
business information (CBI). Anything submitted using SPeCS cannot later 
be claimed to be CBI. The State must confer with the Regional Office 
for the procedures to submit CBI information. All CBI must be clearly 
marked as CBI.
    (b) If no designated facility is located within a State, the State 
shall submit a letter of certification to that effect to the 
Administrator within the time specified in paragraph (a) of this 
section. Such certification shall exempt the State from the 
requirements of this subpart for that designated pollutant. The State 
must submit the letter using the SPeCS, or through an analogous 
electronic reporting tool provided by the EPA for the submission of any 
plan required by this subpart.
* * * * *
    (i) The State must submit, with the plan or revision, documentation 
of meaningful engagement including a list of identified pertinent 
stakeholders and/or their representatives, a summary of the engagement 
conducted, a summary of stakeholder input received, and a description 
of how stakeholder input was considered in the development of the plan 
or plan revisions.


0
7. Amend Sec.  60.24a by:
0
a. Revising paragraphs (b) introductory text, (c), (d), (e), and (f); 
and
0
b. Adding paragraphs (g), (h), and (i).
    The revisions and additions read as follows:


Sec.  60.24a  Standards of performance and compliance schedules.

* * * * *
    (b) Standards of performance shall be in the form of an allowable 
rate, quantity, or concentration of emissions, except when it is not 
feasible to prescribe or enforce such a standard of performance. The 
EPA shall identify such cases in the emission guidelines issued under 
Sec.  60.22a. Where standards of performance prescribing design, 
equipment, work practice, or operational standards, or combination 
thereof are established, the plan shall, to the degree possible, set 
forth the emission reductions achievable by implementation of such 
standards, and may permit compliance by the use of equipment determined 
by the State to be equivalent to that prescribed.
* * * * *
    (c) Except as provided in paragraph (e) of this section, standards 
of performance shall be no less stringent than the corresponding 
emission guideline(s) specified in this part, and final compliance 
shall be required as expeditiously as practicable, but no later than 
the compliance times specified in an applicable subpart of this part.
    (d) Any compliance schedule extending more than twenty months from 
the date required for submittal of the plan must include legally 
enforceable increments of progress to achieve compliance for each 
designated facility or category of facilities. Unless otherwise 
specified in the applicable emission guideline, increments of progress 
must include, where practicable, each increment of progress specified 
in Sec.  60.21a(h) and must include such additional increments of 
progress as may be necessary to permit close and effective supervision 
of progress toward final compliance.
    (e)(1) The State may apply a standard of performance to a 
particular designated facility that is less stringent than or has a 
compliance schedule longer than otherwise required by an applicable 
emission guideline taking into consideration that facility's remaining 
useful life and other factors, provided that the State demonstrates 
with respect to each such facility (or class of such facilities) that 
the facility cannot reasonably achieve the degree of emission 
limitation determined by the EPA based on:
    (i) Unreasonable cost of control resulting from plant age, 
location, or basic process design;
    (ii) Physical impossibility or technical infeasibility of 
installing necessary control equipment; or
    (iii) Other circumstances specific to the facility.
    (2) For the purpose of this paragraph (e), the State must 
demonstrate that there are fundamental differences between the 
information specific to a facility (or class of such facilities) and 
the information EPA considered in determining the degree of emission 
limitation achievable through application of the best system of 
emission reduction or the compliance schedule that make achieving such 
degree of emission limitation or meeting such compliance schedule 
unreasonable for that facility.
    (f) If the State makes the required demonstration in paragraph (e) 
of this section, the plan may apply a standard of performance that is 
less stringent than required by an applicable emission guideline.
    (1) The standard of performance applied under this paragraph (f) 
must be no less stringent (or have a compliance schedule no longer) 
than is necessary to address the fundamental differences identified 
under paragraph (e) of this section. To the extent necessary to 
determine a standard of performance satisfying that criteria, the State 
must evaluate the systems of emission reduction identified in the 
applicable emission guideline using the factors and evaluation metrics 
EPA considered in assessing those systems, including technical 
feasibility, the amount of emission reductions, the cost of achieving 
such reductions, any nonair quality health and environmental impacts, 
and energy requirements. The States may also consider, as justified, 
other factors specific to the facility that were the basis of the 
demonstration under paragraph (e) as well as other systems of emission 
reduction in addition to those EPA considered in the applicable 
emission guideline.
    (2) A standard of performance under this paragraph (f) must be in 
the form as required by the applicable emission guideline.
    (g) Where a State applies a standard of performance pursuant to 
paragraph (f) of this section on the basis of an operating condition(s) 
within the designated facility's control, such as remaining useful life 
or restricted capacity, the plan must also include such operating 
condition(s) as an enforceable requirement. The plan must also include 
requirements to provide for the implementation and enforcement of the 
operating condition(s), such as requirements for monitoring, reporting, 
and recordkeeping.
    (h) A less stringent standard of performance must meet all other 
applicable requirements, including in this subpart and in any 
applicable emission guideline.

[[Page 80544]]

    (i) Nothing in this subpart shall be construed to preclude any 
State or political subdivision thereof from adopting or enforcing, as 
part of the plan:
    (1) Standards of performance more stringent than emission 
guidelines specified in this part; or
    (2) Compliance schedules requiring final compliance at earlier 
times than those specified in applicable emission guidelines.
    (ii) [Reserved]

0
8. Amend Sec.  60.25a by revising paragraph (a) to read as follows:


Sec.  60.25a  Emission inventories, source surveillance, reports.

    (a) Each plan shall include an inventory of all designated 
facilities, including emission data for the designated pollutants and 
any additional information related to emissions as specified in the 
applicable emission guideline. Such data shall be summarized in the 
plan, and emission rates of designated pollutants from designated 
facilities shall be correlated with applicable standards of 
performance. As used in this subpart, correlated means presented in 
such a manner as to show the relationship between measured or estimated 
amounts of emissions and the amounts of such emissions allowable under 
applicable standards of performance.
* * * * *

0
9. Amend Sec.  60.27a by:
0
a. Revising paragraph (a);
0
b. Adding paragraphs (b)(1) and (2);
0
c. Revising paragraphs (c), (d), (f) introductory text, and (g)(1);
0
d. Removing the word ``and'' from the end of paragraph (g)(2)(viii);
0
e. Redesignating paragraph (g)(2)(ix) as paragraph (g)(2)(x); and
0
f. Adding new paragraph (g)(2)(ix) and paragraphs (h), (i) and (j).
    The revisions and additions read as follows:


Sec.  60.27a  Actions by the Administrator.

    (a) The Administrator may, whenever he determines necessary, amend 
the period for submission of any plan or plan revision or portion 
thereof.
    (b) * * *
    (1) Full and partial approval and disapproval. In the case of any 
plan or plan revision on which the Administrator is required to act 
under this paragraph (b), the Administrator shall approve such plan or 
plan revision as a whole if it meets all of the applicable requirements 
of this subpart. If a portion of the plan or plan revision meets all 
the applicable requirements of this subpart, the Administrator may 
approve the plan or plan revision in part and disapprove in part. The 
plan or plan revision shall not be treated as meeting the requirements 
of this chapter until the Administrator approves the entire plan or 
revision as complying with the applicable requirements of this subpart.
    (2) Conditional approval. The Administrator may approve a plan or 
plan revision based on a commitment of the State to adopt and submit to 
the Administrator specific enforceable measures by a date certain, but 
not later than twelve months after the date of conditional approval of 
the plan or plan revision. Any such conditional approval shall be 
treated as a disapproval if the State fails to comply with such 
commitment.
    (c) The Administrator will promulgate, through notice-and-comment 
rulemaking, a Federal plan, or portion thereof, at any time within 
twelve months after:
    (1) The State fails to submit a plan or plan revision within the 
time prescribed or the State has failed to satisfy the minimum criteria 
under paragraph (g) of this section as of the time prescribed in 
paragraph (g)(1) of this section; or
    (2) The Administrator disapproves the required State plan or plan 
revision or any portion thereof, as unsatisfactory because the 
applicable requirements of this subpart or an applicable emission 
guideline under this part have not been met.
    (d) The Administrator will promulgate a final Federal plan, or 
portion thereof, as described in paragraph (c) of this section unless 
the State corrects the deficiency, and the Administrator approves the 
plan or plan revision, before the Administrator promulgates such 
Federal plan.
* * * * *
    (f) Prior to promulgation of a Federal plan under paragraph (d) of 
this section, the Administrator will conduct meaningful engagement with 
pertinent stakeholders and/or their representatives and provide the 
opportunity for at least one public hearing in either:
* * * * *
    (g) * * *
    (1) General. Within 60 days of the Administrator's receipt of a 
State submission, the Administrator shall determine whether the minimum 
criteria for completeness have been met for a plan submission or 
revision. Any plan or plan revision that a State submits to the EPA, 
and that has not been determined by the EPA within 60 days after the 
Administrator's receipt of a State submission to have failed to meet 
the minimum criteria, shall on that date be deemed by operation of law 
to meet such minimum criteria. Where the Administrator determines that 
a plan submission does not meet the minimum criteria of this paragraph 
(g), the State will be treated as not having made the submission and 
the requirements of this section regarding promulgation of a Federal 
plan shall apply.
    (2) * * *
    (ix) Documentation of meaningful engagement, including a list of 
pertinent stakeholders or their representatives, a summary of the 
engagement conducted, and a summary of stakeholder input received, and 
a description of how stakeholder input was considered in the 
development of the plan or plan revisions; and
* * * * *
    (h) The requirements of this paragraph (h) apply to parallel 
processing. A State may submit a plan requesting parallel processing 
prior to adoption and to completion of public outreach and engagement 
by the State in order to expedite review and to provide an opportunity 
for the State to consider EPA comments prior to submission of a final 
plan for final review and action. Under these circumstances and at the 
discretion of the EPA, the following exceptions to the completeness 
criteria under paragraph (g)(2) of this section apply to plans 
submitted explicitly for parallel processing:
    (1) The letter required by paragraph (g)(2)(i) of this section must 
request that EPA propose approval of the proposed plan by parallel 
processing;
    (2) In lieu of paragraph (g)(2)(ii) of this section, the State must 
submit a schedule for final adoption or issuance of the plan;
    (3) In lieu of paragraph (g)(2)(iv) of this section, the plan must 
include a copy of the proposed/draft regulation or document, including 
indication of the proposed changes to be made to the existing approved 
plan, where applicable;
    (4) In lieu of paragraph (g)(2)(ix) of this section, the plan must 
include documentation of the engagement conducted prior to the parallel 
processing submittal and of any planned additional meaningful 
engagement to be conducted prior to adoption of the final plan; and
    (5) The requirements of paragraphs (g)(2)(v) through (viii) of this 
section do not apply to plans submitted for parallel processing. The 
exceptions granted in the preceding sentence apply only to EPA's 
determination of proposed action and all requirements of paragraph 
(g)(2) of this section must be met prior to publication of EPA's final 
determination of plan approvability.

[[Page 80545]]

    (i) The requirements of this paragraph (i) apply to calls for plan 
revisions. Whenever the Administrator finds that the applicable plan is 
substantially inadequate to meet the requirements of the applicable 
emission guidelines in this part, to provide for the implementation of 
the applicable requirements, or to otherwise comply with any applicable 
requirement of this subpart or the Clean Air Act, the Administrator 
shall require the State to revise the plan as necessary to correct such 
inadequacies. The Administrator must notify the State of the 
inadequacies and such plan revisions shall be submitted to the 
Administrator within twelve months or as determined by the 
Administrator. Such findings and notice must be public.
    (1) Any finding under this paragraph (i) shall, to the extent the 
Administrator deems appropriate, subject the State to the requirements 
of this part to which the State was subject when it developed and 
submitted the plan for which such finding was made, except that the 
Administrator may adjust any dates applicable under such requirements 
as appropriate.
    (2) If the Administrator makes this finding on the basis that a 
State is failing to implement an approved plan, or part of an approved 
plan, the State may submit a demonstration to the Administrator it is 
adequately implementing the requirements of the approved State plan in 
lieu of submitting a plan revision. Such demonstration must be 
submitted by the deadline established under this paragraph (i).
    (j) The requirements of this paragraph (j) apply to error 
corrections. Whenever the Administrator determines that the 
Administrator's action approving, disapproving, or promulgating any 
plan or plan revision (or portion thereof) was in error, the 
Administrator may in the same manner as the approval, disapproval, or 
promulgation revise such action as appropriate without requiring any 
further submission from the State. Such determination and the basis 
thereof shall be provided to the State and public.

0
10. Amend Sec.  60.28a by revising paragraph (a) to read as follows:


Sec.  60.28a  Plan revisions by the State.

    (a) Any significant revision to a State plan shall be adopted by 
such State after reasonable notice, public hearing, and meaningful 
engagement. For plan revisions required in response to a revised 
emission guideline, such plan revisions shall be submitted to the 
Administrator within fifteen months, or as determined by the 
Administrator, after publication in the Federal Register of a final 
revised emission guideline under Sec.  60.22a. All plan revisions must 
be submitted in accordance with the procedures and requirements 
applicable to development and submission of the original plan.
* * * * *

0
11. Amend Sec.  60.29a by revising the introductory text to read as 
follows:


Sec.  60.29a  Plan revisions by the Administrator.

    After notice and opportunity for public hearing in each affected 
State, and meaningful engagement for any significant revision, the 
Administrator may revise any provision of an applicable Federal plan 
if:
* * * * *
[FR Doc. 2023-25269 Filed 11-16-23; 8:45 am]
BILLING CODE 6560-50-P


