Proposed Rule2025-11281
Air Plan Approval; California; Eastern Kern Air Pollution Control District; Stationary Combustion Turbines
Primary source
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Published
June 20, 2025
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve a revision to the Eastern Kern Air Pollution Control District (EKAPCD or "District") portion of the California State Implementation Plan (SIP). This revision concerns emissions of oxides of nitrogen (NO<INF>X</INF>) from stationary gas turbines. We are proposing to approve a local rule to regulate these emission sources under the Clean Air Act (CAA or "Act"). We are taking comments on this proposal and plan to follow with a final action.
Full Text
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<title>Federal Register, Volume 90 Issue 117 (Friday, June 20, 2025)</title>
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[Federal Register Volume 90, Number 117 (Friday, June 20, 2025)]
[Proposed Rules]
[Pages 26232-26235]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2025-11281]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-0060; FRL-12608-01-R9]
Air Plan Approval; California; Eastern Kern Air Pollution Control
District; Stationary Combustion Turbines
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a revision to the Eastern Kern Air Pollution Control District
(EKAPCD or ``District'') portion of the California State Implementation
Plan (SIP). This revision concerns emissions of oxides of nitrogen
(NO<INF>X</INF>) from stationary gas turbines. We are proposing to
approve a local rule to regulate these emission sources under the Clean
Air Act (CAA or ``Act''). We are taking comments on this proposal and
plan to follow with a final action.
DATES: Comments must be received on or before July 21, 2025.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2025-0060 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. For comments submitted at
<a href="http://Regulations.gov">Regulations.gov</a>, follow the online instructions for submitting
comments. Once submitted, comments cannot be edited or removed from
<a href="http://Regulations.gov">Regulations.gov</a>. The EPA may publish any comment received to its public
docket. Do not submit electronically any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. The EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system). For
additional submission methods, please
[[Page 26233]]
contact the person identified in the FOR FURTHER INFORMATION CONTACT
section. For the full EPA public comment policy, information about CBI
or multimedia submissions, and general guidance on making effective
comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>. If you need assistance in a language other than English or if
you are a person with a disability who needs a reasonable accommodation
at no cost to you, please contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT: La Kenya Evans-Hopper, EPA Region IX,
75 Hawthorne St., San Francisco, CA 94105; telephone number: (415) 972-
3245; email address: <a href="/cdn-cgi/l/email-protection#1b7e6d7a756873746b6b7e6935777a707e75627a5b7e6b7a357c746d"><span class="__cf_email__" data-cfemail="553023343b263d3a252530277b39343e303b2c34153025347b323a23">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.
Table of Contents
I. The State's Submittal
A. What rule did the State submit?
B. Are there other versions of this rule?
C. What is the purpose of the submitted rule revision?
II. The EPA's Evaluation and Action
A. How is the EPA evaluating the rule?
B. Does the rule meet the evaluation criteria?
C. Proposed Action and Public Comment
III. Incorporation by Reference
IV. Statutory and Executive Order Reviews
I. The State's Submittal
A. What rule did the State submit?
Table 1 lists the rule addressed by this proposal with the dates
that it was adopted by the local air agency and submitted to the EPA by
the California Air Resources Board (CARB).
Table 1--Submitted Rule
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Local agency Rule No. Rule title Amended Submitted
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EKAPCD............................ 425 Stationary Gas Turbines 11/13/2024 12/12/2024
(Oxides of Nitrogen).
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The EPA has reviewed the SIP submittal containing the documents
listed in Table 1 and finds that it fulfills the completeness criteria
in 40 CFR part 51, appendix V.
B. Are there other versions of this rule?
On June 15, 2023, we approved an earlier version of Rule 425 into
the SIP in a limited approval and limited disapproval action (88 FR
39182). The EKAPCD adopted revisions to the SIP-approved version on
November 13, 2024, and CARB submitted them to us on December 12, 2024.
If we take final action to approve the November 13, 2024 version of
Rule 425, this version will replace the previously approved version of
this rule in the SIP.
C. What is the purpose of the submitted rule revision?
Emissions of NO<INF>X</INF> contribute to the production of ground-
level ozone, smog, and particulate matter (PM), which harm human health
and the environment. Section 110(a) of the CAA requires states to
submit plans that provide for the implementation, maintenance, and
enforcement of the National Air Ambient Quality Standards (NAAQS). In
addition, CAA sections 182(b)(2) and (f) in combination require that
SIPs for ozone nonattainment areas classified as ``Moderate'' or higher
implement Reasonably Available Control Technology (RACT) for any
category of sources covered by a Control Techniques Guidelines document
and for any major stationary source of volatile organic compounds
(VOCs) or NO<INF>X</INF>. The EKAPCD has jurisdiction over the Kern
County (Eastern Kern) ozone nonattainment area. The area is classified
as ``Moderate'' for the 1997 8-hour ozone NAAQS, ``Severe-15'' for the
2008 8-hour ozone NAAQS, and ``Serious'' for the 2015 8-hour ozone
NAAQS.\1\ Therefore, EKAPCD must implement RACT in this ozone
nonattainment area consistent with CAA sections 182(b)(2) and 182(f).
The District relies on Rule 425 to establish RACT-level controls for
combustion turbines at major sources of NO<INF>X</INF> within the ozone
nonattainment area.
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\1\ See 40 CFR 81.305. For the 2008 ozone NAAQS, EKAPCD's
voluntary reclassification to ``Serious'' from ``Moderate'' was
finalized on July 5, 2018 (83 FR 31334) and the voluntary
reclassification to ``Severe-15'' was finalized on June 7, 2021 (86
FR 30204). EKAPCD's voluntary reclassification to ``Serious'' for
the 2015 ozone NAAQS was finalized on October 28, 2021 (86 FR
59648).
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In our June 15, 2023 limited approval and limited disapproval of
the 2018 SIP submission of Rule 425 the EPA evaluated the RACT
stringency of the combustion turbine regulations established by Rule
425 and the limited disapproval portion of that action started a
sanctions clock based on the deficient portion of that rule. The
current submission was submitted to address that deficiency.
Rule 425 controls emissions of NO<INF>X</INF> from stationary gas
turbines (units) equal to or greater than 0.88 megawatts (MW) operating
in the EKAPCD. The EPA's 2023 limited approval and limited disapproval
of Rule 425 found that the rule established RACT level controls for all
of the sources covered by the rule, except for the Westinghouse W251B10
unit with a separately specified limit. The current submission of Rule
425 is intended to cure the deficiencies related to this unit. The
EPA's technical support document (TSD) has more information about this
rule.
II. The EPA's Evaluation and Action
A. How is the EPA evaluating the rule?
Rules in the SIP must be enforceable (see CAA section 110(a)(2)),
and must not interfere with applicable requirements concerning
attainment, reasonable further progress, or other CAA requirements (see
CAA section 110(l)). As explained above, EKAPCD must implement RACT in
this area pursuant to CAA sections 182(b)(2) and (f), and the District
relies on Rule 425 to establish RACT-level controls for combustion
turbines at major sources of NO<INF>X</INF> within the Eastern Kern
ozone nonattainment area. In our June 15, 2023 action, we found that
Rule 425 was largely consistent with the relevant CAA requirements.
However, in that final rulemaking, we identified certain deficiencies
that prevented full approval of Rule 425. This proposed rule focuses on
the deficiencies identified in that June 15, 2023 limited approval and
limited disapproval and proposes to determine that the revisions to
Rule 425 correct the previous deficiencies.
Guidance and policy documents that we used to evaluate
enforceability, interference under CAA section 110(l), and rule
stringency requirements for the applicable criteria pollutants include
the following:
1. ``Issues Relating to VOC Regulation Cutpoints, Deficiencies, and
Deviations,'' EPA, May 25, 1988 (the Bluebook, revised January 11,
1990).
2. ``Guidance Document for Correcting Common VOC & Other Rule
Deficiencies,'' EPA Region 9, August 21, 2001 (the Little Bluebook).
3. ``NO<INF>X</INF> Emissions from Stationary Gas Turbines,'' EPA
453/R-93-007, January 1993.
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4. ``Determination of Reasonably Available Control Technology and
Best Available Retrofit Control Technology for the Control of Oxides of
Nitrogen from Stationary Gas Turbines,'' CARB, May 18, 1992.
B. Does the rule meet the evaluation criteria?
Based on our evaluation, this rule meets CAA requirements and is
consistent with relevant guidance regarding enforceability, RACT, and
SIP revisions. In our June 15, 2023 limited approval and limited
disapproval we found that although the emission limitations in the 2018
version of the rule were generally consistent with the RACT
requirement, a relaxation of the emission limitation for a Westinghouse
W251B10 NO<INF>X</INF> unit was higher than the limits applicable to
such units in the SIP-approved version of Rule 425 at that time and not
accompanied with support demonstrating that it met the RACT
requirement. The relaxation in the rule was also not accompanied by an
analysis demonstrating compliance with the section 110(l) prohibition
on SIP modifications that would interfere with attainment, reasonable
further progress, or other requirements of the Act. The deficiencies
with the NO<INF>X</INF> emission limitation for the Westinghouse
W251B10 unit were the only identified deficiencies that were the basis
for our limited disapproval. Our proposed approval of the present SIP
submission of Rule 425 does not otherwise alter our previous
determination that Rule 425 establishes RACT-level controls for all
sources subject to the rule, except for the identified deficiencies
related to the Westinghouse W251B10 unit. As a result, in this action,
we focus our analysis primarily on the revisions that have been made to
the rule and supporting analysis to cure the previously identified
deficiency and serve as the basis for now proposing to approve the
rule.
The revised version of Rule 425 lowers the Westinghouse W251B10
NO<INF>X</INF> gaseous emission limitation from 25 parts per million by
volume (ppmv) to 20 ppmv.\2\ As described in our 2023 action,\3\ the
NO<INF>X</INF> emission limitations from the 1993 version of Rule 425
were calculated as a function of the thermal efficiency (EFF), lower
heating value, and the higher heating value of the unit depending on
fuel type. The gaseous limit in the 1993 version equated to a 20 ppmv
emission limitation when operating at an EFF of 25 or below, and scaled
up with higher EFF values (for example, the ppmv limit associated with
an EFF of 31.25 was 25 ppmv). The 25 ppmv limit in the 2018 version of
the rule resulted in a weakening of the standard under certain
operating conditions when compared to the 1993 version of Rule 425.
This weakening, without sufficient explanation, was the basis of our
limited disapproval of the 2018 version of the rule in 2023. The
submitted version that the EPA is proposing action on now tightens this
limit to 20 ppmv in all operating conditions. This change addresses the
previous section 110(l) issue that was identified in our 2023 action by
setting a limit that is as strong as, and in some operating conditions
stronger than, the limit in the 1993 version of the rule. Moreover,
because the new limit of 20 ppmv is strictly lower than the 25 ppmv
limit contained in the 2018 version, the new rule is stronger than that
version as well.
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\2\ The District also removed the liquid fuel limit for the
Westinghouse W251B10 turbine, because the turbine does not operate
on liquid fuel and is only approved to run on gaseous fuel.
\3\ ``Technical Support Document for EPA's Rulemaking for the
California State Implementation Plan; Eastern Kern Air Pollution
Control District Rule 425 Stationary Gas Turbines (Oxides of
Nitrogen),'' February 2023, p.7.
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In addition, the EKAPCD provided facility operating and retrofit
cost information to demonstrate that a lower limit would not be
reasonably available for this unit.\4\ The EPA's evaluation of this
information indicates that retrofitting the Westinghouse W251B10
turbine with selective catalytic reduction would likely cost $13,000 or
more per ton of NO<INF>X</INF> reductions.\5\ This is not an
economically feasible cost for the purpose of the RACT requirement. For
this reason, as well as additional support and analysis that is found
in our TSD, the EPA proposes that the NO<INF>X</INF> limit of 20 ppmv
represents a RACT level of control for the Westinghouse W251B10 turbine
and corrects the previously identified deficiency. The revised rule
also included an administrative update to add reporting requirements
where performance test data, excess emissions, and continuous
monitoring system performance data must be submitted to the District
every six months. Our evaluation of the remainder of the rule remains
unchanged from our 2023 analysis, and we propose to find that the rule
establishes RACT level controls.
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\4\ Response to Eastern Kern Air Pollution Control District
Request regarding the SIP and Rule 425 Modification, sent on January
3, 2024 (Response Document).
\5\ This value is calculated by reproducing the SCR cost per ton
calculations found in Attachment 6 of the Response Document, sent on
January 3, 2024, but substituting more conservative cost and
emission values, found elsewhere in the Response Document. The
details of this calculation are provided in the TSD.
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Considering the most recent revisions to Rule 425 as submitted to
EPA, we propose to fully approve Rule 425 as meeting all applicable CAA
requirements and consistent with relevant guidance regarding
enforceability, RACT, and SIP revisions.
C. Proposed Action and Public Comment
As authorized in section 110(k)(3) of the Act, the EPA proposes to
approve the submitted rule because it fulfills all relevant
requirements. If we take final action to approve the submitted rule,
our final action will incorporate this rule into the federally
enforceable SIP. We will accept comments from the public on this
proposal until July 21, 2025.
If we finalize this rulemaking as proposed, EKAPCD will have
corrected the deficiencies identified in our prior June 15, 2023
limited disapproval, and all associated sanctions and Federal
implementation plan clocks would be permanently stopped, and any
already applied sanctions would be permanently lifted. We are
concurrently making an interim final determination to stay and defer
the CAA section 179 sanctions associated with our June 15, 2023 limited
disapproval of Rule 425. Consistent with our order of sanction
regulations,\6\ this determination is based on this proposed approval
of a SIP revision to resolve the deficiencies that were the basis of
our June 15, 2023 limited disapproval.
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\6\ See 40 CFR 52.31.
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III. Incorporation by Reference
In this rule, the EPA is proposing to include in a final EPA rule
regulatory text that includes incorporation by reference. In accordance
with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by
reference Eastern Kern Air Pollution Control District, Rule 425,
Stationary Gas Turbines (Oxides of Nitrogen), amended on November 13,
2024 that regulates NO<INF>X</INF> from stationary gas turbine engines
equal to or greater than 0.88 MW. The EPA has made, and will continue
to make, these materials available through <a href="https://www.regulations.gov">https://www.regulations.gov</a>
and at the EPA Region IX Office (please contact the person identified
in the FOR FURTHER INFORMATION CONTACT section of this preamble for
more information).
IV. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP
submission
[[Page 26235]]
that complies with the provisions of the Act and applicable federal
regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP
submissions, the EPA's role is to approve state choices, provided that
they meet the criteria of the CAA. Accordingly, this proposed action
merely proposes to approve state law as meeting federal requirements
and does not impose additional requirements beyond those imposed by
state law. For that reason, this proposed action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Orders 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it proposes to approve a state program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian Tribe
has demonstrated that a Tribe has jurisdiction. In those areas of
Indian country, the rule does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen oxides, Ozone,
Reporting and recordkeeping requirements, Volatile organic compounds.
Dated: June 2, 2025.
Joshua F.W. Cook,
Regional Administrator, Region IX.
[FR Doc. 2025-11281 Filed 6-18-25; 8:45 am]
BILLING CODE 6560-50-P
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