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[Federal Register Volume 89, Number 245 (Friday, December 20, 2024)]
[Rules and Regulations]
[Pages 104043-104059]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-29956]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R06-OAR-2021-0029; FRL-12218-02-R6]

Air Plan Disapproval; Texas; Control of Air Pollution From 
Visible Emissions and Particulate Matter

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA, the Act), the 
Environmental Protection Agency (EPA) is disapproving a revision to the 
Texas State Implementation Plan (SIP) submitted by the State of Texas 
through the Texas Commission on Environmental Quality (TCEQ) on August 
20, 2020 (2020 SIP revision). The 2020 SIP revision addresses emissions 
during planned Maintenance, Startup and Shutdown (MSS) activities for 
certain Electric Generating Units (EGUs) and includes requirements 
intended to address visible emissions (opacity) and Particulate Matter 
(PM) emissions during planned MSS activities. The requirements are 
included in eight Agreed Orders (AOs) issued by TCEQ to the affected 
EGUs and provided in the 2020 SIP revision. EPA determined that the 
requirements contained in these AOs do not meet the CAA enforceability 
requirements or the CAA requirement that emission limitations must 
apply on a continuous basis. We are taking this action in accordance 
with section 110 of the Act.

DATES: This rule is effective on January 21, 2025.

ADDRESSES: The EPA has established a docket for this action under 
Docket ID No. EPA-R06-OAR-2021-0029. All documents in the docket are 
listed on the https://www.regulations.gov website. Although listed in 
the index, some information is not publicly available, e.g., 
Confidential Business Information or other information whose disclosure 
is restricted by statute. Certain other material, such as copyrighted 
material, is not placed on the internet. Publicly available docket 
materials are available electronically through https://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Michael Feldman, Regional Haze and 
SO2 Section, EPA Region 6 Office, 1201 Elm Street, Suite 
500, Dallas, Texas 75270, (214) 665-9793, [email protected]. 
Please call or email the contact listed above if you need alternative 
access to material indexed but not provided in the docket.

SUPPLEMENTARY INFORMATION: Throughout this document ``we,'' ``us,'' and 
``our'' means the EPA.

I. Background and Summary of Bases for Disapproval

    The background for this action is discussed in detail in our 
September 3, 2024, proposal (89 FR 71237). In that document, we 
proposed to disapprove a revision to the SIP submitted by the State of 
Texas through the TCEQ on August 20, 2020, that addresses emissions 
during planned MSS activities for specified EGUs and includes 
requirements intended to address visible emissions (opacity) and PM 
emissions during planned MSS activities at these specified EGUs.
    The 2020 SIP revision and included AOs were intended to address 
concerns regarding the applicability of two long standing Texas rules 
during periods of MSS.\1\ Texas included in the 2020 SIP revision the 
State's interpretation of these rules, taking the position that the 
numerical opacity and PM limits have never applied to coal fired EGUs 
using ESPs during periods of MSS because of

[[Page 104044]]

the technical limitations on the control technology. This 
interpretation was first provided by TCEQ in 2015 as part of a Title V 
action; \2\ this is the first time the interpretation has been included 
as part of a SIP revision. The State's regulatory language contains no 
indication that the rules do not apply to this specific subset of 
sources during MSS.
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    \1\ Specifically: 30 Texas Administrative Code (TAC) 111.111 
(originally adopted as Texas Air Control Board (TACB) Regulation I, 
Rule 103), which limits opacity; and 30 TAC 111.153(b) (originally 
adopted as TACB Regulation I, Rule 105.31), which limits particulate 
matter emissions from solid fuel fired-steam generators to 0.3 lbs/
million Btu averaged over a two-hour period. TACB Regulation I, 
Rules 103 and 105.31 were approved by EPA on May 31, 1972 (37 FR 
10895); these rules were subsequently revised (amendments most 
recently approved May 8, 1996 (61 FR 20732), and April 28, 2009 (74 
FR 19144)), which renumbered and recodified these rules to what they 
are today.
    \2\ See letter, from Steve Hagle, Deputy Director, Office of 
Air, TCEQ to Gina McCarthy, Administrator, EPA, dated December 2, 
2015 (setting forth TCEQ's interpretation that the opacity and PM 
emission limitations in 30 TAC 111.111 and 30 TAC 111.153(b) never 
applied to periods of planned MSS activities at coal-fired EGUs 
equipped with ESPs as a control device).
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    In the instant SIP revision, Texas provided Agreed Orders that 
contain operational requirements and work practices that would apply 
during periods of MSS at EGU's equipped with ESPs. Texas also provided 
historic ambient particulate matter monitoring data, explaining that 
even though under its interpretation, these rules have never applied 
during MSS, there have not been any violations of PM NAAQS measured 
anywhere near these sources.
    EPA has considered three interrelated provisions of the Clean Air 
Act (CAA) in assessing the approvability of this SIP submission. First, 
the requirement under CAA section 110(a)(2)(A) which requires that SIPs 
include ``enforceable emission limitations and other control measures, 
means, or techniques (including economic incentives such as fees, 
marketable permits, and auctions of emissions rights), as well as 
schedules and timetables for compliance, as may be necessary or 
appropriate to meet the applicable requirements of this chapter.''
    Second, under CAA section 302(k), ``emission limitation'' and 
``emission standard'' mean 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.
    Finally, 110(l) provides that the Administrator shall not approve a 
revision of a plan if the revision would interfere with any applicable 
requirement concerning attainment and reasonable further progress (as 
defined in section 7501 of this title), or any other applicable 
requirement of this chapter.
    In our September 3, 2024, proposal (89 FR 71237), we proposed 
disapproval of this SIP revision because these AOs were not enforceable 
as required by CAA section 110 and did not provide for continuous 
limitation of emissions as required by CAA section 302(k). Our review 
under 302(k) in the proposed action was based on language in the SIP 
revision that seems to clearly indicate the reason Texas submitted 
these agreed orders was to make these MSS requirements federally 
enforceable so that emission limitations apply on a continuous basis as 
required under 302(k). As discussed in detail in the response to 
comments, Texas provided comments on our proposed action indicating 
that it did not intend that these emission restrictions be considered 
emission limits as defined by Section 302.
    After careful review of all comments, we are finalizing our 
disapproval. We are finding that the agreed orders are not enforceable 
as required by 110(a)(2)(A). The rules are not enforceable because the 
requirements do not clearly demark as to when start up ends and 
compliance with the 30 TAC chapter 111 numerical limits is required, 
and during startup and shutdown, the work practice requirements for 
when an ESP must be engaged or removed from service are overly vague 
and do not define specific conditions to identify when and what steps 
must be followed to engage and operate the ESPs during these events. 
For periods of maintenance, the only requirement is to follow good air 
pollution control practices and safe operating practices.
    We are also determining that it is necessary or appropriate for 
these measures to be considered emission limitations as defined by 
302(k) and thus must be continuous. Clearly this is supported by the 
explanation accompanying the SIP submission that indicated this 
revision was provided to make the limits continuous under 302(k). Texas 
commented, however, on our proposed action that it was not its intent 
that these agreed orders be considered as emission limitations. As 
discussed fully in our comment response on this matter, EPA disagrees. 
First, Texas indicates these limits are used in the permitting context 
to implement BACT which under the States and EPA definition of BACT 
must be continuous. Second, these AOs as written would allow for 
emissions that could threaten the State's ability to comply with the 
requirements of the CAA, and the NAAQS in particular. Given that on a 
lbs/hour basis, these MSS emissions can be much higher than emissions 
during normal controlled operation, it is necessary and appropriate 
that measures be in place to provide for attainment and maintenance of 
the NAAQS. This conclusion is supported by modeling evidence provided 
by a commenter which suggests that, in fact, uncontrolled emissions 
during MSS could result in violations of the PM NAAQS.
    We are finding that the Agreed Orders do not provide for continuous 
emission limitation as required by 302(k). During MSS, the AOs have 
various requirements intended to limit the duration of the MSS though 
as discussed in our proposal and further in the response to comments, 
the limits on duration are often not clearly defined and thus not 
practical to enforce. Moreover, all of the AOs allow during this time 
period for coal to be burned for a time period which the ESP is not 
operating with no actual limitation on quantity, rate or concentration 
either through a numeric limit or clearly defined work practice that 
would affect emissions. Effectively, the emission limitation is not 
continuous.
    EPA is not basing its disapproval on 110(l), but we do note that 
the modeling provided by one commenter convincingly indicates that the 
monitoring evidence provided in the SIP revision is not sufficient to 
show that the SIP revision does not interfere with attainment or 
maintenance of the NAAQS. It is clear from the modeling that potential 
impacts from MSS activities would occur much closer to the affected 
facilities than the monitors upon which Texas' demonstration is based. 
A future SIP revision to address this disapproval would likely need to 
include modeling to provide evidence that the NAAQs is protected in 
areas in closer proximity to the affected facilities.
    Finally, EPA is cognizant of the technical issues with ESPs that 
impact their effectiveness at lower temperatures. Still, two commenters 
both indicated that to comply with EPA's Mercury and Air Toxics 
Standards (MATS) rule, they do not fire coal until the ESP is 
energized. While these requirements are not in this SIP revision, EPA 
believes that there may be a solution that can be built, hopefully to 
avoid duplicative SIP and MATs requirements and ensuring both NAAQS and 
Air Toxics requirements are met. We look forward to discussions with 
the State and affected operators to resolve these long outstanding 
issues.

II. Response to Comments

    The comment period for the proposed action closed on October 3, 
2024. We received comments on our proposal from several commenters. 
This section contains the EPA's response to the more

[[Page 104045]]

significant comments regarding the EPA's proposed action. For responses 
to all comments received see the Response to Comments Document (RTC) 
available in the docket for this action. We received two comments after 
the close of the comment period. We fully address those comments in the 
RTC document available in the docket for this action.\3\ After careful 
consideration of all comments received, we are finalizing this action 
as proposed.
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    \3\ EPA is only required to consider those comments that are 
received during the comment period; however, it is within EPA's 
discretion to consider comments received after the close of the 
comment period.
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A. General Comments on EPA's Bases for Disapproval

    Comment: Some commenters argue that the proposed disapproval by the 
EPA relies on principles that lack a valid basis in the Clean Air Act 
(CAA), specifically citing Sections 110(a)(2)(A) and 302(k) regarding 
enforceable emission limitations. Certain commenters, including NSSGA 
and Luminant, urge the EPA to withdraw its disapproval and approve the 
Texas SIP provisions, arguing that the proposal is inconsistent with 
CAA principles and relevant judicial decisions. One commenter (Sierra 
Club) supports EPA's proposed disapproval and agrees that the 2020 SIP 
revision violates the CAA.
    Response: EPA disagrees with the comments that our proposed 
disapproval at issue here relies on principles that lack a valid basis 
in the CAA and is inconsistent with CAA principles and relevant 
judicial decisions. States have discretion regarding how best to meet 
their obligations to implement, attain, maintain, and enforce the 
NAAQS, as long as they meet applicable statutory and regulatory 
requirements. A State's SIP submission to address attainment, 
maintenance, and enforcement of the NAAQS or other SIP requirements can 
include a wide variety of types of provisions, such as: source-specific 
emissions limitations and associated monitoring, recordkeeping, and 
reporting; applicable State or local rules (or State laws) regarding 
controls on sources or categories of sources; other local or State 
commitments to undertake certain activities; and non-regulatory 
supporting information.\4\ The EPA evaluates and acts on SIP 
submissions on a case-by-case basis through notice and comment 
rulemaking. The Agency reviews each submission against the applicable 
CAA requirements for that particular submission, which can vary based 
on program requirements and the relevant NAAQS.
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    \4\ Basic Information About Air Quality SIPs, https://www.epa.gov/air-quality-implementation-plans/basic-information-about-air-quality-sips (last updated January 20, 2023).
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    In the Supreme Court's recent decision in Loper Bright, the Court 
recognized that Congress may delegate (and often has delegated) 
discretionary authority to agencies. See Loper Bright Enters. v. 
Raimondo, 144 S. Ct. 2244, 2268 (2024). Applicable to this action, 
Congress has delegated to EPA the responsibility and authority to 
approve or deny SIP submittals. Section 110(k)(3) of the Clean Air Act 
(CAA) states, in relevant part, that a ``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.'' Further, section 110(l) of 
the CAA states that EPA ``shall not approve a revision of a plan if the 
revision would interfere with any applicable requirement concerning 
attainment and reasonable further progress . . . , or any other 
applicable requirement of this chapter.'' Here, the State submitted the 
AOs as site specific SIP requirements that the EPA evaluated for 
compliance with the CAA. For the reasons described at length in other 
responses, the proposal, and the final rulemaking, this SIP submission 
does not comply with the CAA, and thus EPA's disapproval is 
appropriate.

B. Comments on Applicability of the Rules in 30 TAC 111

    Comment: A number of commenters indicate that the limits in Title 
30, Texas Administrative Code, Chapter 111 (30 TAC 111) have never 
applied during MSS to EGUs controlled by electrostatic precipitators 
(ESPs). Some commenters point out that EPA acknowledged in the proposal 
preamble that the technical features of ESPs make it unlikely these 
sources can comply during MSS operations with the numerical limits laid 
out in 30 TAC 111. Commenters take issue with the fact that the 
proposal also points out that there is no textual indication in the 
language of the regulations that the rules do not apply to power plants 
controlled by ESPs during MSS. One commenter points out that the 
statement ignores parallel provisions establishing exemptions for MSS 
periods, such as Texas Air Control Board Rule 12.2 (1972), which TCEQ 
has consistently presented to EPA at each stage of the dialogue, and 
states that EPA's observation about the immediate text of Chapter 111 
at best elevates form over substance, and as a disapproval basis, such 
an approach is clearly impermissible.
    Response: The EPA disagrees with the commenters' assertions that 
the applicability of the rules in 30 TAC 111 has been clear. The first 
time that TCEQ explained with any clarity that these rules never 
applied to periods of planned MSS activities at coal-fired EGUs 
equipped with ESPs as a control device was in an interpretive letter 
dated December 2, 2015, from Steve Hagle, Deputy Director, Office of 
Air, TCEQ to Gina McCarthy, Administrator, EPA, (2015 interpretive 
letter). The 2015 interpretive letter was developed as part of a Title 
V proceeding. The 2020 SIP revision is the first time that Texas 
presented its interpretation with clarity as part of a SIP revision and 
attempted to define the time period allowed for MSS in the SIP and, by 
extension, the time period for when the rules in 30 TAC 111 do not 
apply. Although TCEQ issued these sources MSS permits to authorize 
these emissions during the time period of MSS and the permits have 
conditions addressing the length of time allowed for MSS, a permit 
cannot revise the SIP.\5\
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    \5\ Commenter's reference to TACB Rule 12.2 is unavailing for 
similar reasons. As part of the preamble to EPA's approval, the 
Agency specifically stated the following: ``Several State plans 
include regulations under which an owner or operator could be exempt 
from compliance with an applicable emission limitation if he can 
show that emissions from the source will not interfere with the 
attainment or maintenance of the national standards. The 
Administrator neither approves nor disapproves such optional control 
features. States are advised, however, that action taken to allow 
any such exemptions will constitute revision of a State plan and 
therefore will be subject at that time to the Administrator's 
approval.'' 37 FR 10842, 10845 (May 31, 1972). In other words, Rule 
12.2 may have established a process for Texas and then EPA to 
approve exemption provisions that comply with the CAA (i.e. through 
the SIP submission process) but did not establish any exemptions 
from TAC 111 limits on its own.
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    In the proposal, EPA did not take a position on whether the rule 
previously applied during MSS to power plants controlled by ESPs. 
Instead, we evaluated the 2020 SIP revision as necessary, under the 
State's interpretation and as described in the SIP revision, to make 
the emission limits continuous and federally enforceable. As discussed 
elsewhere, we do not believe the AOs are enforceable or provide for 
continuous limitations on emissions. We believe a SIP revision is 
necessary under TCEQ's interpretation, to clearly define the time 
period of allowed MSS, to provide for continuous emission limitations, 
and to ensure the work practices or other limitations that apply during 
periods of MSS are enforceable. In addition, based on the modeling that 
was provided in comments on this action, it does not appear that an 
interpretation that

[[Page 104046]]

indicates the rules in 30 TAC 111 do not apply during MSS is protective 
of the NAAQS. A future SIP revision will need to demonstrate, 
consistent with CAA section 110(l), that the limitations or work 
practices included in the revision are protective of the NAAQS.

C. Comments on EPA Authority

    Comment: A number of commenters claim that EPA exceeded its 
authority in evaluating the AOs as emission limitations in 
contradiction of the D.C. Circuit's opinion in Environmental Committee 
of the Florida Electric Power Coordinating Group, Inc. v. EPA, 94 F.4th 
77 (D.C. Cir. 2024). The commenters point out that the Clean Air Act 
grants States primary responsibility for deciding what emission 
reductions will be required and from which source. The EPA's 
responsibility is to ensure SIP revisions comply with the Act's 
requirements. If a SIP revision meets the Act's requirements, EPA must 
approve the revision. Commenters indicate that States have primary 
responsibility to craft SIPs, including the ``emission limitations, 
control measures means or techniques . . . as may be necessary or 
appropriate to meet the applicable requirements'' of the CAA. 
Commenters argue that EPA's proposal not only inappropriately redefines 
section 110(a)(2)(A) of the Act, but it also takes the discretion away 
from States to determine what constitutes enforceable, appropriate, or 
necessary emission limitations to be incorporated into a SIP.
    Response: The CAA grants States a central role in regulating air 
quality through the creation and implementation of SIPs, which outline 
state-specific strategies to meet the National Ambient Air Quality 
Standards (NAAQS) and other applicable CAA requirements. The States 
must ensure that SIPs include enforceable emission limitations, 
compliance schedules, and monitoring systems. EPA agrees that States 
have considerable flexibility in choosing how to meet Federal 
standards. However, the EPA must review the SIPs to ensure compliance 
with Federal law and other CAA requirements and approve SIP submittals 
that comply and disapprove those that do not. Congress established a 
framework of mandatory requirements within which States may exercise 
their considerable discretion to design SIPs to provide for attainment 
and maintenance of the NAAQS and to meet other CAA requirements.\6\ 
This view was affirmed in Environ. Comm. Fl. Elec. Power v. EPA, 94 
F.4th at 93:
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    \6\ See 80 FR. at 33877-33879 for a lengthier discussion of the 
Train v. Natural Resource Defense Council line of cases and how the 
Supreme Court views EPA's role as more than ministerial in approving 
SIPs and also views CAA 110(a)(2)(A) as imposing more requirements 
than simply whether or not the SIP leads to NAAQS attainment and 
maintenance.

    [W]hile states generally have ``the power to determine which 
sources w[ill] be burdened by regulation and to what extent,'' Union 
Elec. Co. v. EPA, 427 U.S. 246, 269, 96 S. Ct. 2518, 49 L. Ed. 2d 
474 (1976), the Act `` `subject[s] the states to strict minimum 
compliance requirements' and gives EPA the authority to determine a 
state's compliance with the requirements,'' Michigan v. EPA, 213 
F.3d 663, 687, 341 U.S. App. DC 306 (D.C. Cir. 2000) (quoting Union 
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Elec. Co., 427 U.S. at 256-57).

While it is initially the State's responsibility to determine which 
110(a)(2)(A) emission limitations and other control measures are 
necessary or appropriate to attain and maintain the NAAQS and meet 
other CAA requirements, the D.C. Circuit made it clear that the final 
determination of what is ``necessary or appropriate'' is EPA's 
responsibility:

    To be sure, EPA could determine that the hypothetical state is 
wrong in concluding that its chosen mix of ``other control 
measures'' is ``necessary or appropriate'' to meet the NAAQS. If so, 
EPA might decide that, for the state to meet the NAAQS, at least one 
of the ``other control measures'' must be adjusted such that it 
satisfies the definition of an ``emission limitation''--including, 
for instance, by converting it from a discontinuous to a continuous 
measure.\7\
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    \7\ Environ. Comm. Fl. Elec. Power v. EPA, 94 F.4th at 101. The 
Supreme Court has affirmed that a measure of discretion is due to 
federal agencies when they are empowered to ``regulate subject to 
the limits imposed by a term or phrase that leaves agencies with 
flexibility, such as `appropriate' or `reasonable.' '' Loper Bright, 
144 S. Ct. at 2263. The type of statutory language in CAA section 
110(a)(2)(A) (``as may be necessary or appropriate to meet the 
applicable requirements of this chapter . . .'') is squarely within 
the type of language the Supreme Court was referring to that allows 
EPA to take the ultimate discretionary role in determining what is 
``necessary or appropriate.''

    EPA agrees that States have the primary responsibility to determine 
what measures will be included in a SIP as necessary to meet the Act's 
requirements and that EPA must approve a SIP revision if it meets the 
Act's applicable requirements. In this instance, far from ignoring the 
State's discretion, we read the 2020 SIP revision and took it at face 
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value. The SIP revision stated:

    The proposed SIP revision would make certain operational limits 
and work practices for periods of planned MSS at the listed EGUs 
federally enforceable so that emission limitations apply on a 
continuous basis (at all times of operation) (see FCAA, Sec.  
110(a)(2)(A)--SIP must contain emission limits, measures, etc. and 
Sec.  302(k)--emission limits apply on a continuous basis to assure 
continuous emission reduction).

    This statement appears to indicate that Texas intended for the 2020 
SIP revision to create emission limitations that apply on a continuous 
basis and are federally enforceable. Moreover, this is consistent with 
the understanding between Texas and EPA that is documented in the 
letter exchange between Guy Donaldson, Associate Director, Air Branch, 
Air and Radiation Division, EPA Region 6, dated March 13, 2017, and 
Steve Hagle, Deputy Director, Office of Air, TCEQ, dated June 7, 2017 
(Hagle letter). The Hagle letter stated the purpose of the AOs would be 
to include enforceable opacity and particulate emissions limitations 
for periods of planned startup and shutdown activities.
    As commenters have pointed out, TCEQ undertook this SIP revision to 
resolve a Title V problem after the EPA was petitioned under Title V to 
object to Texas using MSS permits issued under its NSR program to 
revise the SIP to provide exemptions from the rules in Chapter 111 
during MSS. As is discussed in Section II.B, in its 2015 interpretive 
letter, Texas put forward its explanation that the rules did not apply 
to coal fired boilers with ESPs during MSS. This interpretation left 
the SIP without clarity on the allowed time periods for MSS and when 
the Chapter 111 rules would apply. Moreover, the understanding between 
TCEQ and EPA, as documented in the exchange of letters,\8\ makes clear 
EPA's expectation that the SIP should provide for continuous emission 
limitations.
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    \8\ Letter from Guy Donaldson, Associate Director, Air Branch, 
Air and Radiation Division, EPA to Steve Hagle, Deputy Director, 
Office of Air, TCEQ, dated March 13, 2017, and June 7, 2017 return 
letter from Steve Hagle. Included in the docket for this action.
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    In sum, the EPA has the authority to review the 2020 SIP revision 
as an emission limit subject to the requirements of 302(k) and we are 
only evaluating what is written in the SIP and our understanding from 
the discussions leading up to the development of the SIP revision.
    To the extent TCEQ no longer believes continuity is necessary or 
appropriate for the 30 TAC 111 provisions and the AOs, EPA disagrees, 
as is described in additional detail in Section II.D of this document.

D. Comments on D.C. Circuit Decision and ``Emission Limitations''

    Comment: Numerous commenters discuss the D.C. Circuit's recent 
decision in Environmental Committee of Florida Electric Power 
Coordinating

[[Page 104047]]

Group v. EPA, 94 F.4th 77 (D.C. Cir. 2024) and its implications for 
whether or not the emissions limits in the AOs should count as 
``emissions limitations'' as defined in section 302(k) of the CAA. 
Commenters state that, per the court's decision, not all emission 
limits in a SIP necessarily need to qualify as ``emission limitations'' 
under CAA 110(a)(2)(A), which requires that SIPs ``include enforceable 
emission limitations and other control measures, means or techniques . 
. . as may be necessary or appropriate to meet the applicable 
requirements of this chapter'' (emphasis added). Commenters argue that 
EPA has not determined whether it is necessary or appropriate for the 
AOs to qualify as emissions limitations, and that the Agency should not 
play ``semantic gotcha games'' to thus qualify them. Commenters claim 
that it is not necessary or appropriate for the AOs to qualify as 
emissions limitations, as they are work practices established as BACT. 
Commenters also claim that EPA's 2015 SSM policy \9\ has been overruled 
and that the court found that exemption provisions in other State SIPs 
were acceptable.
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    \9\ See State Implementation Plans: Response to Petition for 
Rulemaking; Restatement and Update of EPA's SSM Policy Applicable to 
SIPs; Findings of Substantial Inadequacy; and SIP Calls To Amend 
Provisions Applying to Excess Emissions During Periods of Startup, 
Shutdown and Malfunction, 80 FR 33840 (June 12, 2015).
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    One commenter states that Texas admitted that the SIP provisions at 
issue were ``emissions limitations'' and thus need to be continuous. 
Commenter also argues that the SIP provisions are ``necessary or 
appropriate'' to meet CAA requirements both because they were 
originally submitted in order to provide for attainment and maintenance 
of the NAAQS, and because commenter has modeled NAAQS violations.
    Response: It is important at the outset to be very clear about what 
is contained within the D.C. Circuit's opinion in Florida Electric and 
what is not. EPA agrees with commenters that the D.C. Circuit held that 
section 110(a)(2)(A) of the CAA requires only that emission limitations 
(as defined in section 302(k)) be continuous and that a particular SIP 
provision is only required to be an ``emission limitation'' if it is 
``necessary or appropriate to meet'' applicable CAA requirements. In 
particular, the court held that EPA ``would need to find that, to 
enable a State to meet the NAAQS or some other `applicable 
requirement,' it is `necessary or appropriate' that emissions 
restrictions subject to automatic exemptions satisfy the statutory 
definition of an `emission limitation.' '' \10\
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    \10\ 94 F.4th at 102.
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    Crucially, the court did not find that the emissions limits with 
automatic exemptions that EPA had SIP called were acceptable or 
appropriate. In fact, the court explicitly withheld judgment as to 
whether the ``called SIPs' relevant emission restrictions in fact 
amount to (or must amount to) `emission limitations' per the statutory 
definition.'' \11\ The court stated that if EPA ``were to determine 
that, for states to meet the CAA's applicable requirements, it is 
`necessary or appropriate' for their emission reduction measures to 
meet the statutory definition of `emission limitations' and operate 
during SSM periods, the agency could explain and implement that 
rationale and its action would be subject to judicial review.'' \12\ 
That is precisely what EPA is doing in this final action: determining 
that it is necessary or appropriate for the emissions reduction 
measures submitted to the Agency by Texas, in conjunction with the 
existing measures, to meet the full definition of ``emissions 
limitation'' under 302(k), and thus they must be continuous.\13\
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    \11\ Id. at 110.
    \12\ Id. Some commenters state that certain SIP provisions that 
EPA SIP called in the 2015 SSM Action for which the SIP call was 
vacated are substantially similar to the AOs. Given that the D.C. 
Circuit did not find that those SIP provisions were appropriate or 
acceptable, their similarity to the AOs is irrelevant.
    \13\ Commenters frame the question as whether or not the AOs 
themselves need to meet the definition of ``emission limitation.'' 
The AOs are intended to cover only periods of MSS; as such, the 
question EPA needs to answer is whether it is necessary or 
appropriate for the AOs combined with the numerical limits in 30 TAC 
111.111 and 30 TAC 111.153 to be ``emission limitations.''
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    The EPA did not explicitly propose to make such a ``necessary or 
appropriate'' determination in the proposed disapproval action because 
the Agency determined that Texas agreed that the AOs were emissions 
limitations as defined under the CAA. The EPA's conclusion was not 
based merely on the fact that Texas used the words ``emission 
limitation'' in its submission, but rather the fact that the submission 
was explicitly intended to create continuous emissions limitations:

    The proposed SIP revision would make certain operational limits 
and work practices for periods of planned MSS at the listed EGUs 
federally enforceable so that emission limitations apply on a 
continuous basis (at all times of operation) (see FCAA, Sec.  
110(a)(2)(A)--SIP must contain emission limits, measures, etc. and 
Sec.  302(k)--emission limits apply on a continuous basis to assure 
continuous emission reduction).\14\
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    \14\ 2020 SIP revision at iv.

    As the D.C. Circuit stated, ``states are initially charged with 
determining whether an `emission limitation' is `necessary or 
appropriate' to meet the CAA's applicable requirements.'' \15\ It is 
true that Texas's submission came before the D.C. Circuit's opinion was 
released; however, EPA could only act on what had been submitted, and 
the only conclusion the Agency could draw was that Texas had initially 
determined that the AOs, in combination with the numerical limits in 30 
TAC Chapter 111, were in fact emissions limitations that should apply 
on a continuous basis. EPA agreed that continuity was required, as is 
discussed at length in the proposal, and thus had no need to make an 
additional determination.
---------------------------------------------------------------------------

    \15\ 94 F.4th at 107.
---------------------------------------------------------------------------

    Regardless of Texas's intentions, EPA agrees that the substance of 
the provisions at issue are more important than their label. As such, 
EPA has reviewed these provisions in detail and determined that it is 
``necessary or appropriate'' for the emissions restrictions, including 
the submitted AOs, to meet the definition of ``emission limitations'' 
in CAA section 302(k).
    First, as is highlighted by the commenters, Texas has approved the 
emissions reduction measures included in the AOs in permits as ``best 
available control technology'' (BACT) for the sources at issue during 
MSS periods. Texas claims that the measures are continuous in part 
because they constitute BACT. BACT is explicitly defined in the CAA and 
EPA's regulations as ``an emission limitation based on the maximum 
degree of reduction of each pollutant subject to regulation. . . .'' 
\16\ In other words, Congress indicated that the combination of 
measures approved as BACT must be emission limitations. In contrast 
with section 110(a)(2)(A), there is no indication that measures 
approved as BACT can be anything other than emission limitations--if it 
constitutes BACT, it must be an emission limitation, and thus must meet 
the CAA definition of emission limitation in section 302(k). If the AOs 
are BACT, they must be emission limitations, and thus must be 
continuous.\17\
---------------------------------------------------------------------------

    \16\ CAA section 169(3); 40 CFR 52.21(b)(12) (emphasis added). 
Texas's definition of BACT incorporates EPA's definition by 
reference. 30 T.A.C. secs. 116.111(a)(2)(C), 116.160(c)(1)(A).
    \17\ This has been EPA's consistent interpretation of the CAA 
since at least 1993. See, e.g., In re Southwestern Electric Power 
Company, Order on Petition No. VI-2014-01 (February 3, 2016), at 8 
(stating that BACT limits apply at all times, including during 
periods of shutdown and malfunction events); In re Cash Creek 
Generation, LLC, Order on Petition No. IV-2010-4 (June 15, 2012), at 
21 (same). TCEQ consistently claims in its comments that the precise 
combination of measures in the AOs are what constitutes BACT. 
However, it is not clear whether what has been approved as BACT also 
includes the lb/hr emission limits for PM that apply during MSS in 
the relevant permits. Those lb/hr limits were not included in the 
AOs submitted for approval into the SIP.

---------------------------------------------------------------------------

[[Page 104048]]

    Second, these AOs as written would allow for emissions that could 
threaten the State's ability to comply with the requirements of the 
CAA, and the NAAQS in particular. In general, SSM exemptions can 
threaten public health and welfare, particularly given that they can 
allow for dramatically higher amounts of emissions than the amount of 
pollutants emitted at other times. For the first time, Texas is 
attempting to clarify and make federally enforceable requirements that 
apply to the relevant sources specifically during MSS periods. However, 
rather than limits that appear on their face to apply at all times, the 
sources governed by the AOs would have periods where no enforceable 
standards apply at all. EPA highlighted the problematic features of the 
AO measures in the proposal. Two particular features could allow for 
essentially unlimited periods of high PM emissions: first, for startup 
and shutdown periods, there are no limits to the frequency of startup 
or shutdown events, and the requirements for when an ESP must be 
engaged are overly vague. Second, for maintenance periods, there are 
essentially no restrictions during certain time periods. As currently 
written, neither Texas nor commenters have shown that the requirements 
in the AOs are protective of the NAAQS.
    In fact, there is quantitative evidence in the record that 
demonstrates approving these AOs could result in NAAQS violations. 
During the public comment period, Sierra Club presented modeling 
showing that the emissions restrictions, or lack thereof, included in 
the AOs have the potential to cause NAAQS violations in the areas 
around the relevant sources. As is discussed in the modeling section, 
Section II.I, the modeling may actually be underestimating the ambient 
air quality in those areas given the overly conservative assumptions 
around background concentrations. As is also discussed in response in 
Section II.H, the modeling presents a more accurate view of the ambient 
air quality near the relevant sources than Texas has provided in its 
submission and comments, given the fact that the monitors cited to by 
Texas are not sited to characterize the air quality near theses 
sources, with the closest monitor being 17 kilometers (km) from the 
sources referenced in the modeling.
    It is true that some sources are currently choosing to be more 
protective than the SIP limits combined with the AOs would require. For 
example, NRG has chosen to burn sub-bituminous coal rather than 
lignite, which results in lower modeled PM concentrations. However, 
those choices are not specifically required under the AOs or the SIP. 
When assessing SIP submissions, Congress has directed EPA to review the 
``enforceable emission limitations and other control measures'' that 
are required under CAA section 110(a)(2)(A)--measures that are not in 
the SIP cannot displace those requirements. The modeling by Sierra Club 
presents a compelling case that, if the AOs are adopted and sources 
decide not to continue to overcomply (for whatever reason--an exogenous 
shock to the system, a change in strategy, court decisions affecting 
other Federal rules, etc.), the AOs as they are currently written are 
not protective of the NAAQS because, in conjunction with the PM and 
opacity limits in 30 TAC 111, they do not apply on a continuous basis. 
As such, EPA is determining that, in order to ensure NAAQS protection, 
it is necessary or appropriate for the AOs to apply continuously when 
incorporated with the 30 TAC 111 p.m. and opacity limits into the SIP, 
and thus the AOs, in conjunction with the limits that apply during non-
MSS periods, must meet the definition of emission limitation.
    EPA agrees with the logic expressed in the comment from Sierra Club 
and, as such, is disapproving the SIP submission. EPA agrees in 
particular that modeling is not always necessary in order for the 
Agency to make a ``necessary or appropriate'' determination, depending 
on the context of the SIP submission. EPA has multiple grounds to find 
that it is ``necessary or appropriate'' for the SIP provisions at issue 
here to be emissions limitations, and thus continuous.

E. Comments on Alternative Emissions Limitations (AEL) Criteria

    Comment: Commenters argue that EPA's reliance on seven recommended 
criteria for assessing the AOs is inappropriate and lacks statutory 
basis, asserting that any standards for evaluating Texas's plans must 
derive from the text of the CAA itself. One commenter also argues that 
``non-applicability'' is not the same as an ``exemption'' provision and 
thus the AEL criteria should not even apply.
    Response: In the context of making recommendations to States for 
how to address emissions during startup and shutdown, the EPA has long 
recommended seven criteria for States to evaluate in establishing 
appropriate alternative emission limitations.\18\ Among the purposes 
for these recommendations was the need to take into account 
technological limitations that might prevent compliance with the 
otherwise applicable emission limitations, while ensuring that those 
alternative limitations complied with the continuity and enforceability 
requirements of the CAA. As a general matter, they provide a framework 
intended to assist States in developing emissions limitations that meet 
the requirements of the CAA. That framework also helps EPA assess 
whether the CAA's requirements are met. These recommendations serve to 
assist in the development of enforceable and continuous requirements 
that would apply during periods when the limits in Chapter 111 for 
normal operation cannot be met due to the technological limitations of 
the ESPs.
---------------------------------------------------------------------------

    \18\ 57 FR 13502 (Apr. 16, 1992).
---------------------------------------------------------------------------

    The recommended seven criteria were re-articulated in the 2015 SSM 
SIP Action, and read as follows: (1) The revision is limited to 
specific, narrowly defined source categories using specific control 
strategies; (2) Use of the control strategy for this source category is 
technically infeasible during startup or shutdown periods; (3) The AEL 
requires that the frequency and duration of operation in startup or 
shutdown mode are minimized to the greatest extent practicable; (4) As 
part of its justification of the SIP revision, the State analyzes the 
potential worst-case emissions that could occur during startup and 
shutdown based on the applicable AEL; (5) The AEL requires that all 
possible steps are taken to minimize the impact of emissions during 
startup and shutdown on ambient air quality; (6) The AEL requires that, 
at all times, the facility is operated in a manner consistent with good 
practice for minimizing emissions and the source uses best efforts 
regarding planning, design, and operating procedures; and (7) The AEL 
requires that the owner or operator's actions during startup and 
shutdown periods are documented by properly signed, contemporaneous 
operating logs or other relevant evidence.
    Any SIP revision establishing an AEL that applies during startup 
and shutdown would be subject to the same procedural and substantive 
review requirements as any other SIP submission. While the EPA compared 
the AOs to these recommendations (specifically we discuss criteria 5 
and

[[Page 104049]]

criteria 6 in the proposed action), the failure to follow these 
criteria is not the basis of the EPA's disapproval.\19\ The EPA 
reviewed whether the AOs could in practice be enforced as required by 
the CAA. The EPA found, as discussed in the proposal and in response to 
comments in Section II.F, that the emission limits were too subjective 
to provide for enforceability and are not continuous.
---------------------------------------------------------------------------

    \19\ See additional discussion on these recommendations in 
response to comments in Section II.F.3. It should also be noted that 
Texas did not give consideration to criteria 4, e.g. the State 
analyzes the potential worst-case emissions that could occur during 
startup and shutdown based on the applicable AEL. See Section II.H 
and.I discussing Sierra Club's modeling evaluation of the potential 
impact of worst case emissions.
---------------------------------------------------------------------------

    The EPA's disapproval of the Texas SIP submission stems from a 
statutorily derived authority conferred upon the agency through 
Congress and our disapproval is based on those authorities.
    TCEQ also commented that the 30 TAC 111 rules do not apply to 
plants equipped with ESPs during MSS periods \20\ and that ``non-
applicability is not the same as exemption'' and thus the AEL framework 
is inapplicable. As we have noted, the AEL framework is simply a series 
of recommendations, and so EPA's review of Texas's submission under 
that framework is meant to provide a helpful lens through which to 
assess the submission for approvability. Nonetheless, ``non-
applicability'' and ``exemption'' are precisely the same thing in this 
context: limits that apply during normal operation and allegedly do not 
apply during periods of MSS. Any other conclusion would be nothing more 
than a ``semantic `gotcha' game.'' Florida Electric, 94 F.4th at 109.
---------------------------------------------------------------------------

    \20\ At various points in TCEQ's comment letter, it makes what 
EPA interprets as drafting errors about its interpretation of the 
scope of the 30 TAC Chapter 111 limits. First, it states ``as TCEQ 
explained in the proposed and adopted SIP narrative and the 
incorporated December 2, 2015, interpretive letter, the PM and 
opacity limits in Sec. Sec.  111.111(a)(1) and 111.153(b) do not 
apply to plants equipped with electrostatic precipitators (ESPs) for 
particulate control.'' Neither the proposed SIP nor the interpretive 
letter make such an extremely broad claim--that the 30 TAC Chapter 
111 limits don't apply at all to plants equipped with ESPs. EPA's 
interpretation is that TCEQ intended to state, as they did in those 
other documents, that the limits do not apply during MSS periods.
    Second, TCEQ states that ``its SIP rules on opacity and PM do 
not apply during periods of SSM for these specific units.'' 
Presumably TCEQ intended to state that those limits do not apply 
during periods of MSS, which covers maintenance periods rather than 
the malfunction periods covered by the acronym ``SSM.'' Otherwise, 
EPA would be required to disapprove the submission as it would be an 
admission by Texas that 30 TAC chapter 111 limits do apply during 
maintenance periods and its new submission would be newly putting in 
place exemptions to those limits during those periods.
---------------------------------------------------------------------------

F. Comments on Enforceability, Continuity, and Adequacy of the AO 
requirements

1. Continuity
    Comment: Commenters argue that, even if the combination of 30 TAC 
111 limits and the work practice and operational standards contained 
within the AOs must meet the definition of ``emission limitation'' and 
thus be continuous, the requirements do apply on a continuous basis and 
thus should be approved. In particular, TCEQ states that the durational 
limits do not allow for uncontrolled operation and are an integral part 
of the permit requirements for MSS that TCEQ determined to be BACT. 
Commenter asserts that time limits are controls because they are set at 
a level that will allow the plants to conduct startups and shutdowns up 
to an annual and daily amount of PM emissions associated with these 
activities. The permits include Maximum Allowable Emissions Table 
(MAERT) limits set at levels that are determined to be protective and 
not interfere with maintenance of the PM NAAQS.
    Response: EPA disagrees with commenter that the AOs operate 
alongside the PM and opacity standards in 30 TAC 111 to create a 
continuous emission limitation. It is true that emissions limitations 
do ``not require that a singular rate or concentration apply on a 
continuous basis. Rather, the limitation can include ``design, 
equipment, work practice, or operational standard[s].'' However, the 
EPA finds that for the AO restrictions that apply during startup and 
shutdown periods, the requirements are overly vague and there are no 
limits to the frequency of startup or shutdown events, allowing for 
essentially unlimited periods of uncontrolled PM emissions. We discuss 
this in more depth in response to other comments. In addition, we find 
that the requirements during planned maintenance do not provide for 
continuous emission limits because there are no restrictions to 
emissions or work practices that apply other than a limit to the total 
annual time of maintenance activities. For these activities, the AOs 
``authorize'' periods of opacity greater than 20% for a number of hours 
per year (e.g., 535 hrs/year for each unit at Martin Lake). The only 
ostensible requirement during maintenance periods appears to be that 
the source operate the boiler and its ESP in accordance with good air 
pollution control practices, safe operating practices, and protection 
of the facility and associated air pollution control equipment. The 
generic general duty that an owner or operator shall operate a source 
consistent with safety and good air pollution control practices for 
minimizing emissions is not sufficient to identify what these specific 
practices might be across the range of maintenance activities to which 
the AOs apply. Therefore, such general duty clauses are not practically 
enforceable as a limitation on emissions during these activities.\21\
---------------------------------------------------------------------------

    \21\ See 80 FR 33840, 33899-900, and 33903-904 (June 12, 2015) 
for an extended discussion of why periods when only a ``general 
duty'' provision applies cannot constitute part of an enforceable, 
continuous emission limitation.
---------------------------------------------------------------------------

    It is important to note that the relevant permits from which the 
AOs originate also include lb/hr PM limits during MSS periods that 
operate in the background of the combination of work practices that are 
contained in the AOs that were submitted to EPA. It is not clear from 
TCEQ's submission or comments whether what has been approved by TCEQ as 
BACT also includes the lb/hr emission limits for PM that apply during 
MSS in the relevant permits. It is also unclear why TCEQ did not 
include those limits in the AOs. As such, we are not specifically 
evaluating those numerical limits as they are not included in the SIP 
submittal. EPA's analysis of whether or not the limits in 30 TAC 111 
combined with the submission operate as a continuous emissions 
limitation might be different if there were additional lb/hr background 
limits that also applied.\22\ In response to comments in Section II.I 
of this document and in the RTC, we discuss modeling submitted by 
Sierra Club that evaluates the potential for emissions during MSS to 
result in violations of the NAAQS and compares the modeled emission 
rates to the permit limits. Texas did not provide modeling with this 
SIP revision. As we discuss elsewhere, there are no limits on frequency 
of MSS events in the AOs and therefore, the durational limits for 
individual startup and shutdown events are not protective of the ton/
year requirements in the permits. Furthermore, the permit limits are 
not permanent because they are not incorporated into the SIP and can 
therefore be revised by the State without a SIP approval.
---------------------------------------------------------------------------

    \22\ To be clear, emissions limitations need not be numerical at 
all times to be continuous, but it is easy to guarantee 
continuousness when a numerical limit applies at all times.

---------------------------------------------------------------------------

[[Page 104050]]

2. Enforceability and Adequacy of AO Requirements
    Comment: A commenter (NRG) states that EPA fails to identify 
benchmarks against which to judge the adequacy of Limestone's work 
practices for frequency or duration, or control-level for MSS 
emissions. Commenter also states that EPA fails to identify any CAA or 
other regulatory authority that suggests frequency, duration, or 
control-level standards for SIP provisions on MSS emissions, nor does 
EPA identify a requirement in the Act or another regulation for which a 
longer duration, higher frequency, or lesser degree of control would 
raise a compliance concern.
    Commenter states that the AO provides clear and enforceable 
constraints and there is no deficiency as to the allowable frequency 
and duration or level of control. Commenter (TCEQ) disagrees with EPA 
that no discussion on the historical frequency of startup events is 
included in the SIP narrative and that periods of startup and shutdown 
have been and continue to be infrequent and intermittent. Commenter 
(NRG) claims that in the 50-year history of the MSS requirements and 
their predecessor provisions, no party has raised concerns with the 
frequency or duration of Limestone's MSS emissions, the level of 
control of emissions, or the practical enforceability of constraints 
imposed on the facility, nor has any issue arisen as to any air quality 
issues associated with those emissions.
    Several commenters mention EPA's use of the term ``practical 
enforceability.'' Some of these commenters argue that the 2020 SIP 
revision is practically enforceable, while others argue that 
``practical enforceability'' is not a requirement in the Act.
    Commenters assert that the EPA disapproved the AOs because they do 
not impose standardized or identical requirements on all sources.
    One commenter (Sierra Club) states that the EPA correctly asserts 
that the CAA requires SIPs to include enforceable emission limits. The 
citizen suit provision in 42 U.S.C. 7604 further supports this by 
allowing citizens to take legal action over violations of SIP limits. 
The provisions in the AOs that allow for exemptions during MSS periods 
(referred to as ``MSS provisions'') violate this enforcement 
requirement by effectively eliminating public access to enforce SIP 
limits during these periods. The MSS provisions are also not 
practically enforceable, as they fail to provide clear standards for 
when equipment, like ESPs, is considered ``in service'' or functioning 
properly to control emissions.
    Response: The EPA disagrees with the commenters arguing that the 
AOs are adequate and enforceable. As an initial matter, the adequacy of 
all SIP submissions are judged against CAA requirements, including that 
they are enforceable and, if they are emission limitations or it is 
necessary or appropriate for them to be emission limitations, that they 
are continuous. Enforceable meaning that the SIP is subject to a legal 
means for ensuring that sources are in compliance with the control 
measure set out in the proposal. In the proposed action, we discuss at 
length the reasons why we find the requirements submitted by the State 
for incorporation into the SIP to not be enforceable. Second, an 
additional requirement for emission limitations in the SIP are that 
they are continuous. We address the determination that is necessary or 
appropriate for the AOs combined with the numerical limits in 30 TAC 
111.111 and 111.153 to be ``emission limitations'' and therefore must 
be continuous in response to separate comments in this document.\23\
---------------------------------------------------------------------------

    \23\ See Section II.C and D
---------------------------------------------------------------------------

    EPA has long used the term ``practical enforceability'' to refer to 
requirements for source specific permits to be federally 
enforceable.\24\ Use of the term ``practical'' is not adding new 
enforceability requirements but seeks to provide clarity on the manner 
in which the source specific requirements are not federally 
enforceable.
---------------------------------------------------------------------------

    \24\ See Guidance an Enforceability Requirements for Limiting 
Potential to Emit through SIP and Sec.  112 Rules and General 
Permits, US EPA, January 25, 1995.
---------------------------------------------------------------------------

    In 1987, EPA laid out enforceability criteria that SIP rules must 
meet.\25\ In general, practical enforceability for a source-specific 
permit term means that the provision must specify: (1) a technically 
accurate limitation and the portions of the source subject to the 
limitation; (2) the time period for the limitation (hourly, daily, 
monthly, annually); and (3) the method to determine compliance 
including appropriate monitoring, record keeping and reporting. For 
rules and general permits that apply to categories of sources, 
practical enforceability additionally requires that the provision (4) 
identify the categories of sources that are covered by the rule; (5) 
where coverage is optional, provide for notice to the permitting 
authority of the source's election to be covered by the rule; and (6) 
recognize the enforcement consequences relevant to the rule.\26\
---------------------------------------------------------------------------

    \25\ See ``Review of State Implementation Plans and Revisions 
for Enforceability and Legal Sufficiency,'' from Michael Alushin, 
Alan Eckert, and John Seitz, September 3, 1987 (1997 SIP memo).
    \26\ Id.
---------------------------------------------------------------------------

    In the instant action, EPA proposed to find that the conditions 
contained within the source specific AOs do not meet the requirements 
for enforceability. The conditions that Texas submitted as part of 
their SIP revision are too subjective to provide EPA with clear methods 
and conditions to be able to practically enforce the limitations should 
the need arise. For example, the AOs submitted as part of the 2020 SIP 
revision include a requirement that ``all the sources must comply with 
the boiler and ESP manufacturer's operating procedures, or the owner/
operator's written Standard Operating Procedures (SOP) manual and to 
operate in a manner consistent with the procedures to minimum 
opacity.'' \27\ However, it is unclear from the 2020 SIP revision what 
procedures should be followed if the SOP is inconsistent with the 
manufacturer's operating procedures. Further, as the SOP can be 
modified over time, the required work practices cannot be considered 
permanent and enforceable. For a measure to be relied on as an emission 
limitation, it must be permanent which means it cannot be revised 
absent following the SIP revision process.
---------------------------------------------------------------------------

    \27\ See source specific AOs included in the docket for this 
action.
---------------------------------------------------------------------------

    We disagree with the commenter that there are ``clear and 
enforceable constraints'' to the frequency or duration of events, as 
there is no limit to the frequency of normal startup or shutdown 
events. Furthermore, the definitions for when startup ends or shutdown 
begins lack clear and measurable requirements by which compliance can 
be determined. Just as limits on the duration of the MSS events were 
identified by TCEQ as BACT and necessary to minimize emissions and 
reflect best management practices and promote the safe, effective 
operation of the respective boiler and ESP, limits on frequency of MSS 
events are necessary to effectively limit the emissions.\28\

[[Page 104051]]

Commenters state that they have strong financial incentives to minimize 
the frequency and duration of MSS periods, however an incentive is not 
the same as an enforceable requirement. Furthermore, while we 
understand that there is a strong economic incentive to avoid downtime 
or periods of MSS in order to provide for efficient generation of 
electricity and sale of product, there does not seem to be an economic 
incentive to bring the ESP up to full operation during MSS due to the 
operating costs required to run the ESP. This is why it is important to 
define in a clear and enforceable requirement for when operation of the 
ESP should be initiated, and more importantly, when compliance with the 
limits in TAC Ch. 111 is required. As discussed elsewhere in this 
document, comments from Sierra Club (including modeling) confirm our 
concern with this level of emissions, showing that the emissions 
restrictions provided in the AOs could potentially threaten attainment 
and maintenance and cause NAAQS violations in the areas around the 
relevant sources. As we noted in the proposed action, this is of 
particular concern as utilization of coal-fired power generation has 
become more variable and planned startup and shutdown events may occur 
more frequently than they have in the past. Even intermittent or 
infrequent events can potentially impact the NAAQS, in particular the 
24-hr PM NAAQS that is based on the very high end (98th percentile) of 
24-hour average concentrations in a year, which would be equivalent to 
the 8th highest day in the year when evaluating modeling.\29\ In the 
2020 SIP revision, TCEQ provides that data from Electric Reliability 
Council of Texas (ERCOT) for calendar year 2018 shows for the five 
sources in ERCOT there were 46 days during which a unit was in startup 
mode.\30\ Providing data from one year is not sufficient to identify 
any variability in frequency of MSS events from year to year or any 
recent trends of increased frequency that would indicate whether past 
performance is indicative of future expected practice. Regardless, 
there are no enforceable limitations on frequency in the AOs or SIP.
---------------------------------------------------------------------------

    \28\ See 2020 SIP revision at Section 2.2.2: ``Special 
conditions in the EGUs' NSR permits were designed to provide a 
federally enforceable limit for emissions during planned MSS 
activities when the ESPs are operated outside the optimal range. The 
conditions define the startup and shutdown periods and establish 
durational limits for these activities in order to minimize 
emissions. The time limits in the special conditions reflect best 
management practices and promote the safe, effective operation of 
the respective boiler and ESP. Minimizing emissions using good air 
pollution control procedures and best management practices are 
considered BACT for the planned MSS activities. These conditions are 
specifically incorporated into the AOs for the respective EGUs.'' We 
note that it is not clear whether what has been approved as BACT 
also includes the lb/hr emission limits for PM that apply during MSS 
in the relevant permits. Those lb/hr limits were not included in the 
AOs submitted for approval into the SIP.
    \29\ 40 CFR part 50.20 and 40 CFR part 50 Appendix N. 40 CFR 
part 50.20(b) ``The primary annual PM2.5 standard is met 
when the annual arithmetic mean concentration, as determined in 
accordance with appendix N to this part, is less than or equal to 
9.0 [micro]g/m3.: 40 CFR part 50.20(c) ``The primary 24-hour 
PM2.5 standard is met when the 98th percentile 24-hour 
concentration, as determined in accordance with appendix N to this 
part, is less than or equal to 35 [micro]g/m3.'' 40 CFR part 50 
Appendix N clarifies the specific procedures for calculating the PM 
2.5 design values. See Appendix N for details, but in general the PM 
2.5 annual NAAQS design value is the average of three consecutive 
years annual arithmetic mean concentrations, and the PM 2.5 24-hour 
NAAQS design value is the average of three consecutive years of the 
annual 98th percentile of 24-hour values.
    \30\ See 2020 SIP submission at Section 2.2.1.
---------------------------------------------------------------------------

    We also disagree with the commenter (NRG) that the AOs provide 
``clear and enforceable constraints'' with respect to the level of 
control required. The commenter does not specifically address any of 
the deficiencies in the requirements identified by EPA in the proposed 
action that make the requirements vague and unenforceable. For example, 
for NRG Limestone, the AO requires the ESP be placed into service as 
soon as practical after the air heater outlet temperature is between 
200 and 300 degrees Fahrenheit. It is unclear why a range is specified 
rather than a minimum temperature or if there are other measurable 
parameters, such as flow rate or drum metal temperature, that are being 
evaluated to determine when it would be ``practical'' to place the ESP 
into service. Once the air heater outlet temperature is within the 
specified range, there are no specific conditions identified to define 
when it is required to place the ESP in service beyond ``as soon as 
practical,'' and no way to independently verify if the ESP was in fact 
placed into service as soon as practical. The commenter simply restates 
the requirements in the AO and states that they are clear and 
enforceable. Similarly, for NRG Limestone, the AO states that one 
condition required to identify when a startup ends is when the ESP is 
``fully optimized'' but there are no specific conditions identified to 
define when the ESP is to be considered fully optimized. As identified 
by commenters (Sierra Club), the requirements do not define what it 
means to place an ESP ``into service'' and do not specify how the ESP 
must be operated during the startup period. This allows the ESPs to be 
operated at widely varying performance levels during startup, with some 
or all ESPs operating at much lower efficiencies (e.g., by turning on 
one or two fields during startup) than the equipment is capable of 
achieving.
    We disagree with the commenter that there is no deficiency with 
respect to the required operating procedures during MSS events. It is 
unclear what procedures should be followed for startup and shutdown if 
requirements in the SOP are inconsistent with the manufacturer's 
operating procedures. In addition, the owner/operator's SOP can be 
modified over time, and therefore the required work practices cannot be 
considered permanent and enforceable. As discussed in the proposed 
notice, we also find that the general duty provisions that apply during 
maintenance activities in the AOs are not practically enforceable. The 
generic general duty that an owner or operator shall operate a source 
consistent with safety and good air pollution control practices for 
minimizing emissions is not sufficient to identify what these specific 
practices might be across the range of maintenance activities to which 
the AOs apply, and thus such general duty clauses are not practically 
enforceable as a limitation on emissions during these activities.\31\ 
The AOs do not include any work practices that the sources are required 
to apply during these maintenance periods. For these activities, the AO 
for NRG Limestone ``authorize'' periods of opacity greater than 15% for 
535 hrs/year for each unit. As we discuss elsewhere, because emission 
limitations must be continuous, they cannot include gaps or periods 
during which sources are not required to limit their emissions and 
thus, for example, cannot include exemptions for emissions during 
periods of operation such as MSS. We find that these requirements are 
neither enforceable nor continuous.
---------------------------------------------------------------------------

    \31\ See 80 FR 33840, 33899-900, and 33903-904 (June 12, 2015) 
for an extended discussion of why periods when only a ``general 
duty'' provision applies cannot constitute part of an enforceable, 
continuous emission limitation.
---------------------------------------------------------------------------

    Commenters raise issue with a lack of identified concerns with 
enforceability/adequacy of these provisions or air quality over the 
history of Limestone's MSS practices. However, for the first time, 
Texas is attempting to clarify and make federally enforceable SIP 
requirements through the submitted AOs that apply to the relevant 
sources specifically during MSS periods. These submitted AOs must be 
evaluated for compliance with the CAA requirements, including that they 
are enforceable and protective of the NAAQS. During these events, the 
only requirements that apply are the work standards concerning placing 
the ESP in service as soon as practicable during startup or keeping the 
ESP in service as late as practicable during shutdown. There is no 
requirement for the sources to limit emissions during such events in 
any other way. PM emissions during these events can be much higher than 
normal emissions and there is no limitation on the number of times 
during the year a

[[Page 104052]]

boiler can go through a planned startup or shutdown. As discussed 
elsewhere in this document, the lack of limits to the frequency of 
startup events, and overly vague requirements for when an ESP must be 
engaged, work together to mean that there could be essentially 
unlimited periods of high PM emissions where no enforceable standards 
apply to limit emissions. Neither Texas in the 2020 SIP revision nor 
commenters have shown that the requirements in the AOs are protective 
of the NAAQS. As discussed elsewhere in this document, comments from 
Sierra Club (including modeling) confirm our concern with this level of 
emissions, showing that the emissions restrictions provided in the AOs 
have the potential to cause NAAQS violations in the areas around the 
relevant sources. The historical record of air monitoring data is not 
sufficient to identify air quality concerns as the monitors are not 
located in the vicinity of the sources and therefore cannot be used to 
characterize air quality or impacts from these emissions near the 
sources.
    The EPA disagrees with commenters' assertion that the EPA 
disapproved the AOs because they do not impose standardized or 
identical requirements on all sources.\32\ EPA's disapproval is not 
based on a lack of identicality. In describing the issues with the AOs, 
EPA noted that the AOs vary in level of specificity and then provided 
an analysis of each AO, identifying the different approaches and lack 
of specificity in each approach that makes for an unenforceable 
requirement. At no point did EPA identify a concern with the lack of 
uniformity in the AOs. As explained in the proposed action, we are 
disapproving the 2020 SIP revision because the AOs lack specificity and 
are ambiguous and unenforceable because they are unclear as to the 
procedures an operator must follow to be in compliance and at what 
point in the startup or shutdown process the facility must switch from 
compliance with the AO to compliance with 30 TAC 111.111(a)(1) and 30 
TAC 111.153(b) as required for routine operation.
---------------------------------------------------------------------------

    \32\ Commenters raised the issue of replicability not being a 
valid basis for disapproval, citing Texas v. E.P.A., 690 F.3d 670, 
at 683 (5th Cir. 2012) which holds that replicability is not an 
independent authoritative standard and standards that the EPA uses 
must derive from the CAA itself. This case is not analogous to this 
disapproval as replicability is not used as a basis of disapproval.
---------------------------------------------------------------------------

    One commenter agreed with EPA's view that the AOs are 
unenforceable, stating that in addition to EPA's own enforcement 
powers, the CAA guarantees citizens' ability to directly enforce SIP 
limits. EPA agrees that the citizen suit provisions of the CAA further 
highlight the need for SIP limits like the AOs to be enforceable.
    In summary, we find that the AO restrictions are overly vague and 
unenforceable. We also find that the AO requirements, in combination 
with the requirements in 30 TAC 111, do not provide for continuous 
emission limitations. Finally, we find that the AO requirements have 
not been shown to be protective of the NAAQS.\33\
---------------------------------------------------------------------------

    \33\ See Sections II.G, H and I for additional discussions on 
interference with attainment or maintenance of the NAAQS and 
modeling of potential impacts from MSS emissions.
---------------------------------------------------------------------------

3. EPA's Recommended Measures
    Comment: Commenter (NRG) states the EPA suggests several additional 
``preferred features'' such as use of natural gas, different control 
devices, or reliance on MATS controls for the Agreed Orders. Commenter 
states that these ``preferred features'' are not required to comply 
with the Act and would be redundant, ineffective or inappropriate.
    Response: The ``preferred features'' identified by the commenter 
were provided by EPA as examples of measures that, if taken, would be 
expected to minimize emissions during MSS, not as specifically required 
features of the AOs. They are provided in the context of the 
recommendations for AELs that serve as guidance and not requirements 
for developing emissions limits that apply at times like MSS when 
technological limitations require different limitations on emissions. 
As discussed elsewhere, the AOs as submitted do not provide for 
enforceable requirements during MSS. EPA provided a discussion of 
measures that could be considered to potentially address these 
enforceability deficiencies. For example, if the AOs included a 
requirement to startup using natural gas and only introduce coal once 
the ESP is fully energized, that would be a clear and enforceable 
requirement that would also minimize emissions during startup. 
Similarly, use of a baghouse would also alleviate concerns from 
emissions during MSS. We in no way are suggesting that these are the 
only options for addressing emissions during MSS but provided them as 
examples of options that could be considered in developing approvable 
emission limits that apply during MSS. To the extent that some of these 
specific measures are already available and taken at the facility to 
comply with MATS or other requirements, they would also address 
emissions during MSS, and these can and should be incorporated into the 
SIP to provide for permanent and enforceable requirements during these 
periods. EPA's proposed disapproval was based on the determination that 
the AO requirements are unenforceable and not that they failed to 
include these ``preferred features.''
    We disagree that adoption of these measures into the SIP would be 
redundant as the MATS requirements were promulgated to address 
hazardous air pollutants, such as mercury, and are subject to revision 
and/or court decisions independent of the requirements in the Texas 
SIP. To rely on these requirements to address opacity and PM emissions 
from EGUs with ESPs during MSS in Texas, Texas should adopt the 
requirements into the SIP.
4. Recordkeeping and Reporting
    Comment: Commenters restate the recordkeeping language in the AOs 
and state that these requirements are not deficient. TCEQ states that 
the AOs are all enforceable because each plant operator must maintain 
records demonstrating when the startup or shutdown periods occur, based 
on flue gas temperature at the ESP, and must comply with permitted 
allowable emissions for PM emissions during planned SSM activities. In 
addition, TCEQ comments that EPA's claims are speculative and not based 
on evidence of noncompliance with the identical terms contained in the 
plants' NSR permits that have been in place for over 10 years. NRG 
comments that EPA identifies no basis in the Act for a standard against 
which to evaluate monitoring, recordkeeping, and reporting in an MSS 
provision.
    Commenters also claim that deviation reports required under the 
Title V operating permits provide information to determine compliance.
    Response: We disagree with the commenters. Typically, a primary 
mechanism for ensuring that a SIP provision is legally and practicably 
enforceable is for a State to impose sufficient monitoring, 
recordkeeping, and reporting (MRR) requirements on affected sources. 
CAA section 110(a)(2)(F)(i) speaks more explicitly to the requirement 
for SIPs to provide for emissions monitoring by requiring ``the 
installation, maintenance, and replacement of equipment, and the 
implementation of other necessary steps, by owner or operators of 
stationary sources to monitor emissions from such sources,'' as may be 
prescribed by EPA. EPA has promulgated regulations implementing this 
requirement at 40 CFR 51.214, which requires State SIPs to contain

[[Page 104053]]

legally enforceable procedures to ``[r]equire stationary sources 
subject to emission standards as part of an applicable plan to install, 
calibrate, maintain, and operate equipment for continuously monitoring 
and recording emissions,'' among other requirements. EPA notes that 
monitoring and recordkeeping requirements serve multiple purposes, 
including supporting effective enforcement of SIP requirements. A lack 
of adequate monitoring and recordkeeping requirements can undermine the 
ability of the State, the EPA, and citizens to evaluate or enforce a 
source's compliance with applicable emissions limitations imposed by 
the SIP.
    The AOs require sources to keep records of periods of planned MSS, 
the opacity measured by the continuous opacity monitoring system (COMS) 
for the duration of the planned MSS activities, and the work practices 
followed during the planned MSS activities. As discussed in the 
proposed action, EPA finds that these AOs do not specifically require 
sources to keep records of the parameters used to identify when startup 
or shutdown periods actually occur, such as temperature or unit load, 
or ESP operating parameters. The AOs also do not specifically require 
sources to keep records of the parameters that are monitored (e.g., air 
heater outlet temperature, drum metal temperature, periods when solid 
fuel is burned) to determine whether the ESP should be placed into or 
removed from service during these MSS periods. These are the types of 
specific monitoring records that are necessary to provide adequate 
information to evaluate when startup and shutdown periods actually 
occur or whether Chapter 111 requirements apply and evaluate compliance 
with the AO requirements regarding when the ESPs are required to be 
placed into or removed from service. A requirement to ``identify 
periods of planned MSS'' and the ``work practices followed'' does not 
provide sufficient information to evaluate whether the facility 
accurately recorded the end of a startup or beginning of a shutdown 
event, or whether the ESP was engaged at the appropriate time during 
the startup process. Thus, the monitoring and recordkeeping 
requirements do not provide adequate information to evaluate when a 
startup event ends, and thus whether the AO or Chapter 111 requirements 
should apply at a given time. Therefore, because there is no way to 
evaluate which requirements apply, there is no way to evaluate 
compliance with the applicable requirements.
    The commenter further states that the AO requirements are ``all 
enforceable because each plant operator must maintain records 
demonstrating when the startup or shutdown periods occur, based on flue 
gas temperature at the ESP.'' However, there is no specific requirement 
in the AOs for sources to record or maintain records of flue gas 
temperature. Thus, there are no records available to evaluate when the 
startup or shutdown periods occurred based on the flue gas temperature. 
Furthermore, only Oklaunion's AO specifies a specific temperature (once 
the outlet gas temperature to the ESP is greater than 300 [deg]F) when 
the ESP should be placed into service. The AOs for the other seven 
facilities lack this level of specificity and are not enforceable 
because they require the ESP to be placed into service ``as soon as 
practical.'' This requirement is subjective, and it is unclear how the 
required recordkeeping would provide the necessary information to allow 
for verification that this requirement has been met.
    With respect to the commenter's suggestion that EPA's claims are 
speculative and not based on evidence of noncompliance with the 
identical terms contained in the plants' NSR permits that have been in 
place for over 10 years, this is not relevant to EPA's conclusion that 
the relevant requirements do not have sufficient MRR requirements to 
provide the information necessary to be able to evaluate compliance 
with and enforce the requirements in the future. As explained, 
sufficient MRR requirements are necessary to provide adequate 
information to be able to evaluate compliance with the Chapter 111 and 
AO SSM-related requirements. Whether there is evidence of noncompliance 
with the permit terms that have been in place for 10 years in the past 
has no bearing on the ability to evaluate and enforce compliance with 
the relevant requirements in the future.
    Finally, commenters also claim that deviation reports required 
under the title V operating permits provide adequate information to 
determine compliance. Regardless of whether there are reporting 
requirements in the title V permits as the commenter claims, this does 
not resolve the deficiencies in the monitoring and recordkeeping 
requirements. In other words, a requirement to report monitoring and 
recordkeeping information that is not sufficient to provide the 
information needed to evaluate compliance with the applicable 
requirements is deficient.
    For the reasons explained, the relevant MRR requirements do not 
meet CAA and regulatory requirements and do not provide sufficient 
information to evaluate compliance with and enforce the specified 
rules. As discussed in the proposal and in response to other comments 
in this section, we are disapproving the SIP revision because the 
requirements in the AOs are overly vague and too subjective to provide 
for enforceability. The insufficient MRR requirements further reinforce 
the conclusion that the AOs are not enforceable as written.

G. Comments on Section 110(l) and Interference With Attainment or 
Maintenance of the NAAQS

    Comment: One commenter (Sierra Club) commented that the 2020 SIP 
revision would relax the existing SIP, resulting in interference with 
attainment and maintenance of the NAAQS under CAA section 110(l). 
Therefore, Sierra Club contends that EPA must disapprove the SIP 
revision under CAA section 110(l), in addition to the rationale EPA 
provided at proposal. Specifically, Sierra Club pointed to language in 
our proposal that acknowledged that there is not textual evidence in 
the language of the regulations that indicate that the rules do not 
apply continuously, and thus this SIP revision would relax the existing 
SIP. Sierra Club goes on to say that Texas provided no modeling or 
other evidence that this SIP revision would not interfere with 
attainment or maintenance of the NAAQS to show compliance with CAA 
section 110(l). To further support their comment, Sierra Club provides 
modeling suggesting that in areas in near proximity to two of the 
facilities, there could be violations of the PM NAAQS due to emissions 
allowed under the 2020 SIP revision.
    Contrary to Sierra Club's CAA section 110(l) comment, two 
commenters, TCEQ and the Texas MSS Working Group, indicated that the 
rules in 30 TAC 111 have never applied to these facilities during MSS. 
Further, the Texas MSS Working Group contends that Texas provided a 
``robust'' demonstration under CAA section 110(l) The MSS Working Group 
also noted that EPA did not comment in its proposal on TCEQ's CAA 
section 110(l) demonstration.
    One commenter, NRG, provided late comments (received October 9, 
2024) indicating that the Sierra Club modeling showing potential PM 
NAAQS violations at its Limestone Electric Generating Station did not 
reflect its current operations which utilized cleaner fuels such sub-
bituminous coal instead of lignite and natural gas during startup. NRG 
also argued that EPA's original rationale was not based on

[[Page 104054]]

potential NAAQS violations and that to rely on Sierra Club's modeling, 
the Agency must reopen the public comment period. Luminant also 
submitted late comments (received November 22, 2024) that were similar 
to NRG's comments.\34\
---------------------------------------------------------------------------

    \34\ We fully address these late comments in the RTC document.
---------------------------------------------------------------------------

    Response: EPA agrees that CAA section 110(l) is relevant to all SIP 
revisions and that it makes clear that the Administrator may not 
approve a SIP revision if it would interfere with attainment or 
maintenance of the Act. EPA, however, did not base its proposed 
disapproval on CAA section 110(l). Instead, we based our proposed 
disapproval on concerns, discussed elsewhere, with the enforceability 
and continuousness of the AOs provided in the 2020 SIP revision. In 
this action, we are finalizing our determination that the AOs are (1) 
not enforceable and (2) it is necessary or appropriate for the AOs and 
provisions in 30 TAC 111 to be emissions limitations, and they are not 
continuous in violation of the CAA.
    While our disapproval is not based on failure to meet CAA section 
110(l) requirements, we do believe that Sierra Club's modeling provides 
ample evidence that the TCEQ 110(l) demonstration is not adequate to 
determine that the SIP revision does not interfere with attainment and 
maintenance of the NAAQS. In other words, Sierra Club's modeling 
confirms that we are prohibited from approving this submission. TCEQ's 
110(l) demonstration is based on two arguments. First, TCEQ claims that 
MSS emissions have always been occurring from these facilities and 
never were controlled by the ESPs used by these facilities for control. 
Second, TCEQ states that there has never been evidence detected by 
Texas's PM ambient monitoring network of any PM NAAQS violations. 
Sierra Club provides modeling for two of the facilities covered by the 
2020 SIP revision that indicates that violations of the NAAQS are 
possible, both under the sources' current practices, and to an even 
greater extent if emissions are uncontrolled during MSS to the extent 
allowed under the AOs in the 2020 SIP revision. It is worth pointing 
out that Texas did not provide modeling with this SIP revision. Sierra 
Club's modeling makes clear that any potential violations of the PM 
standard as a result of MSS emissions would be much closer to the 
facilities than any of the monitors Texas points to in its 110(l) 
demonstration. In the absence of relevant monitoring data, modeling has 
long been utilized to estimate impacts of facilities on air quality. In 
this case, Sierra Club used EPA's preferred model, AERMOD, and modeled 
the impact of two of the facilities at 25%, 50%, 75%, and 100% load 
assuming combustion of lignite and separately combustion of sub-
bituminous coal and considering that the ESP would not be energized 
during MSS. The modeling indicates that PM2.5 MSS emissions 
could potentially result in modeled values above the 24-hour 
PM2.5 NAAQS and the annual PM2.5 NAAQS. This 
modeling also suggests that a similar modeling analysis of maximum MSS 
emissions from the other power plant facilities at issue here could 
potentially result in violations of the NAAQS. Violations of the 
standard were indicated at both facilities modeled, with higher 
concentrations modeled when burning lignite. See response to Comments 
on Air Dispersion Modeling Results in this document and the RTC 
Document for full evaluation and discussion of the model results.
    Although the Limestone facility has not burned lignite since 
December 2017, the Limestone units are not restricted by permit or rule 
from the types of fossil fuels that can be fired in its boilers. The 
Martin Lake facility entered into an AO in early 2022 that prohibits 
the facility from burning lignite, but that requirement is currently 
not federally enforceable.\35\ EPA's review of the modeling did not 
detect any significant issues with the modeling techniques themselves 
or the conclusions, although refinements could be performed.\36\ NRG 
claimed that its Limestone facility uses natural gas during startup to 
comply with EPA's MATS rules and that the ESPs are placed into service 
``contemporaneous to solid fuel firing'', which would certainly reduce 
PM emissions to very low levels during this period of operation. 
However, there is no SIP requirement or requirement in the submitted AO 
that NRG is required to burn only natural gas at startup or that would 
prohibit the burning of solid fuel prior to placing the ESP into 
service. Additionally, there is no requirement to burn only sub-
bituminous coal rather than lignite in the SIP or the AOs. NRG could 
decide to change their practices if they are not required to take such 
emissions-reducing measures in the SIP. In addition, this further 
highlights the specific, enforceable measures available to the source 
such as prohibiting burning solid fuel until the ESP is in service, in 
contrast to the vague requirements actually included in the AOs such as 
``placing the ESP into service as soon as practical'' or ``operating 
the facilities and associated air pollution control equipment in 
accordance with good air pollution control practices.''
---------------------------------------------------------------------------

    \35\ This AO was submitted to EPA for approval as part of the 
SO2 NAAQS attainment SIP revision. EPA has not taken 
final action on that submittal at this time. See EPA proposed 
actions 89 FR 63117 (Aug. 2, 2024) and 89 FR 68378 (Aug. 26, 2024).
    \36\ See Section I and the RTC document for additional 
discussion of EPA's review of the modeling
---------------------------------------------------------------------------

    In sum, while Sierra Club's modeling confirms that EPA is 
prohibited from approving this SIP revision, it is unnecessary for EPA 
to base its disapproval on failure to comply with section 110(l) 
requirements. An approvable SIP revision would need to confirm that the 
revision would not interfere with attainment or maintenance of the 
NAAQS or any other applicable CAA requirement. In the absence of 
monitoring data from monitors located closer to the facilities, such a 
demonstration would most likely need modeling. Sierra Club's modeling 
makes clear that such a demonstration would depend on the type of coal 
or other fuel used during startup, and those fuel requirements would 
need to be made enforceable to ensure the SIP revision did not 
interfere with attainment or maintenance.
    In response to NRG's late comment that EPA is not providing 
sufficient notice and must open a new public comment period, it is not 
required that the Agency repropose every time a comment raises new 
evidence to consider. ``To avoid perpetual cycles of new notice and 
comment periods, a final rule that is a logical outgrowth of the 
proposal does not require an additional round of notice and comment 
even if the final rule relies on data submitted during the comment 
period.'' \37\ EPA's final action here is in substance exactly the same 
as its proposal--as the Agency has made clear, these AO requirements 
are not enforceable or continuous and allow for periods of unlimited 
emissions. Sierra Club's modeling is evidence that the emissions can 
interfere with attainment or maintenance of the NAAQS. EPA ``fairly 
apprise[d] interested persons of the subjects and issues'' the Agency 
considered; ``the notice need not specifically identify every precise 
proposal which the agency may ultimately adopt as final rule.'' \38\
---------------------------------------------------------------------------

    \37\ Bldg. Indus. Ass'n v. Norton, 247 F.23d 1241, 1246 (D.C. 
Cir. 2001) (internal citations omitted).
    \38\ Chemical Mfrs. Ass'n. v. EPA, 870 F.2d 177, 203 (5th Cir. 
1989) (internal citations omitted).

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[[Page 104055]]

H. Comments on the Use of Air Dispersion Modeling

    Comment: Sierra Club commented that air quality dispersion modeling 
is a technically appropriate, efficient, and readily available 
technique for evaluating air quality impacts associated with SIP 
submittals and revisions. Sierra Club pointed out that EPA has 
identified the AERMOD steady-state plume dispersion model as the 
Agency's default model for the assessment of both primary and secondary 
particulate matter concentrations from large point sources. Sierra Club 
also indicated that EPA has recognized in analogous circumstances, 
monitoring alone is not generally adequate for identifying the maximum 
concentration of particulate matter impacts from large sources ``[d]ue 
to the generally localized impacts'' from those sources, and the lack 
of nearby monitors. Sierra Club also cited to TCEQ's air monitoring 
network plan, that indicates that there are no PM air quality monitors 
in the vicinity of any of the facilities at issue in this proposal, or 
even in the same county. Sierra Club continued that the use of air 
dispersion modeling is also consistent with the Agency's historic use 
of such modeling for determining compliance with the NAAQS and the use 
of dispersion modeling to demonstrate attainment with the NAAQS is also 
court-validated. Sierra Club summarized that the use of scientifically 
and legally supported air quality dispersion modeling (AERMOD in this 
case) to characterize and evaluate the air quality impacts of Texas's 
2020 SIP revision, including the worst-case emissions from MSS 
operations at those facilities is not only consistent with EPA's 
Appendix W guidance, but it is well supported by EPA's lengthy and 
court-validated history of using AERMOD as a tool for evaluating 
individual source compliance with the NAAQS and is technically 
appropriate and supported by EPA regulations and guidance.
    Response: As discussed in more detail in the RTC document for this 
action, there are no PM2.5 monitors located within 50 km of 
either Luminant's Martin Lake or NRG's Limestone facility. We note that 
three of the eight facilities do have PM2.5 monitors located 
in the same county, but those monitors are not sited near the 
facilities, with the closest being 17 kilometers from the facility.\39\ 
Maximum modeled primary PM concentrations are usually within three 
kilometers of the source and then concentrations drop off quickly with 
increasing distance for these types of facilities in semi-flat terrain. 
Therefore, none of the PM2.5 monitors have been sited to 
pick up the maximum impacts near the sources covered by the 2020 SIP 
revision; therefore, it is necessary to utilize area specific modeling 
to estimate PM2.5 air quality levels around these 
facilities. EPA has utilized modeling to assess air quality standards 
for single facilities in permitting actions, SIPs, enforcement cases, 
and designations since the 1970s.\40\ For example, EPA relied on 
modeling from States, industry, and third-party modeling performed by 
Sierra Club and others during the 1-hour SO2 designations 
for Round 2 and Round 3 designations to assess areas should be 
designated nonattainment or attainment and also to assess the 
appropriate boundaries for the nonattainment areas.\41\ EPA also relied 
on modeling from States and industry in 2008 Lead NAAQS 
designations.\42\ Modeling provides the ability to assess the air 
quality in areas around facilities because it is impractical to site 
monitors everywhere. EPA concurs that modeling with AERMOD in this case 
is the appropriate model to use and is an appropriate technique, 
scientifically and legally, to analyze primary pollutant concentrations 
of PM2.5 in the areas around these facilities when they have 
MSS emissions.\43\
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    \39\ There are PM2.5 monitors in Harrison, Potter and 
Atascosa Counties where the Southwestern Electric Power Company H.W. 
Pirkey, San Miguel Electric Cooperative, Inc. San Miguel and 
Southwestern Public Service Company Harrington Station are 
respective located.
    \40\ Guideline on Air Quality Models versions including 40 CFR 
part 51 Appendix W (current version published November 2024 (FR Vol. 
89, No. 230, November 29, 2024, 95034-95075). The EPA originally 
published the Guideline in April 1978 (EPA-450/2-78-027). The EPA 
revised the Guideline in 1986 (51 FR 32176) and updated it with 
supplement A in 1987 (53 FR 32081), supplement B in July 1993 (58 FR 
38816), and supplement C in August 1995 (60 FR 40465). The EPA 
published the Guideline as Appendix W to 40 CFR part 51 when the EPA 
issued supplement B. The EPA republished the Guideline in August 
1996 (61 FR 41838) to adopt the CFR system for labeling paragraphs. 
The EPA also published updated Guideline in 2003, 2005, and 2017.
    \41\ SO2 designations FR cities including Federal 
Register Vol. 81, No. 133, July 12, 2016, 45039-45055; Federal 
Register Vol. 81, No. 239, December 13, 2016, 89870-89876; Federal 
Register Vol. 83, No. 6, January 9, 2018, 1098-1172.
    \42\ Lead Designations FR Vol. 75, No. 244, November 22, 2010, 
and Texas Area Designations for the 2008 Lead National Ambient Air 
Quality Standards.
    \43\ 40 CFR part 51 App. W Sections 1.0, 4.0 (including 4.2.2.1 
and 4.2.3.5), and Appendix A to Appendix W of Part 51 Summaries of 
Preferred Air Quality Models (Section A.1)
---------------------------------------------------------------------------

    In addition to the citations provided by Sierra Club, EPA's 
reliance on modeling rather than monitoring data was recently upheld by 
the 5th Circuit in Texas v. EPA, 91 F.4th 280 (5th Cir. 2024).\44\ The 
court highlighted that review of an agency's evaluation of complex 
scientific data within its technical expertise--such as the decision 
whether to use modeling or monitoring data in evaluating possible 
attainment issues--is extremely deferential, and that there is a 
`presumption of regularity' that is difficult for challenging parties 
to overcome.\45\ The court applied that standard and found that EPA did 
not act arbitrarily or capriciously in relying on modeling data despite 
the existence of monitoring data.\46\
---------------------------------------------------------------------------

    \44\ See also Galveston-Houston Assoc. for Smog Prevention v. 
EPA, 289 Fed. Appx. 745, 754 (5th Cir. 2008) (upholding use of 
modeling rather than monitoring data).
    \45\ Id. at 291 (citing to BCCA Appeal Grp. v. EPA, 355 F.3d 
817, 824 (5th Cir. 2003) and American Petroleum Inst. v. EPA, 787 
F.2d 965, 983 (5th Cir. 1986)); see also Huntsman Petrochemical LLC 
v. EPA, 114 F.4th 727 (D.C. Cir. 2024).
    \46\ Id. at 293.
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I. Comments on Results of Air Dispersion Modeling

    Comment: Sierra Club indicated that EPA must consider credible 
third-party modeling. Sierra Club has submitted modeling of ``worst 
case'' MSS potential emissions rates for boilers at two of the 
facilities (Luminant's Martin Lake facility and NRG's Limestone 
facility) for multiple load levels spanning from 10% load to 100% load. 
Sierra Club concludes that the modeling results credibly demonstrate 
that effectively uncontrolled PM emissions from Martin Lake and 
Limestone plants during MSS periods, as would be allowed under Texas's 
proposed 2020 SIP revision and its Agreed Orders, could result in 
violations of the annual and 24-hour NAAQS for PM2.5 in 
areas surrounding these two facilities. Sierra Club did not model 
whether MSS emissions from the other power plant facilities at issue 
here could cause violations of the NAAQS, but the modeling results for 
Martin Lake and Limestone suggest that MSS emissions at the other 
facilities could result in violations of the NAAQS.
    NRG provided late comments (received October 9, 2024) indicating 
that the Sierra Club modeling showing potential PM NAAQS violations at 
its Limestone Electric Generating Station overstates Limestone's 
emissions. Luminant also submitted late comments (received November 23, 
2024) on the modeled emission rates and modeling results.\47\
---------------------------------------------------------------------------

    \47\ We fully address these late comments from NRG and Luminant 
in the RTC document.
---------------------------------------------------------------------------

    Response: The EPA obtained the modeling files from Sierra Club (SC) 
and has reviewed both the reports from Wingra (Sierra Club's 
contractor) and

[[Page 104056]]

the modeling files for modeling of MSS emissions from Luminant's Martin 
Lake facility and NRG's Limestone facility. EPA reviewed the different 
components of the modeling and found that overall, it is informative 
and does indicate that ``worst case'' MSS emissions could result in 
modeled violations. EPA is including a summary of two key elements of 
our review related to the emission rates modeled and the representative 
background monitoring concentration added to modeled values here, and 
note that our full review of all the Sierra Club modeling and results 
are included in the RTC document available in the docket for this 
action.
    The SIP revision and the AOs for these two facilities do not 
include any numerical limits on the maximum pounds per hour (lb/hr) 
that could be emitted from each boiler during MSS. As discussed in 
Section II.F.2, the SIP revision with its AOs does not include limits 
on the frequency of startup and shutdown events so there is no 
restriction to the total number of hours per year that the boilers at a 
facility can be in a normal MSS operation situation; therefore, they 
could operate a large number of hours per year and the MSS emissions 
could potentially impact the 24-hour PM2.5 NAAQS and the 
annual PM2.5 NAAQS. Sierra Club modeled MSS emissions for 
every hour of the year and based on the lack of limits on hours of 
operation per year in MSS mode, we find this assumption to be 
reasonable, especially when analyzing the 24-hour PM2.5 
NAAQS, which is based on the very high end (98th percentile) of 24-hour 
average concentrations in a year.\48\ As a check on the reasonableness 
of Sierra Club's assumptions, EPA reviewed Sierra Club's modeled 
emission rates, compared that with the MSS emission limits included in 
the facilities' MSS permits,\49\ and found the Sierra Club's emission 
rates were similar or less than the PM2.5 lb/hr emission 
limits in the permits for NRG Limestone. As discussed in the RTC 
document, we also find that the modeled emission rates for Martin Lake 
are also reasonable. EPA has not fully reviewed the PM2.5 
lb/hr emission limits and the underlying assumptions and calculations 
in the MSS permits for these two facilities to evaluate if they are 
representative of the maximum emissions that could occur during MSS but 
note that some of the other associated limits in the permits (i.e. ash 
content and sulfur content limits) indicate that the maximum emission 
rates could be larger/higher using EPA's emission factors. If higher 
emission rates are possible during MSS, then Sierra Club's maximum 
modeled concentrations would also be expected to be higher if 
appropriately adjusted and remodeled.\50\
---------------------------------------------------------------------------

    \48\ 40 CFR part 50.20 and 40 CFR part 50 Appendix N. 40 CFR 
part 50.20(b) ``The primary annual PM2.5 standard is met 
when the annual arithmetic mean concentration, as determined in 
accordance with appendix N to this part, is less than or equal to 
9.0 [micro]g/m\3\.: 40 CFR part 50.20(c) ``The primary 24-hour 
PM2.5 standard is met when the 98th percentile 24-hour 
concentration, as determined in accordance with appendix N to this 
part, is less than or equal to 35 [micro]g/m\3\.'' 40 CFR part 50 
Appendix N clarifies the specific procedures for calculating the 
PM2.5 design values. See Appendix N for details, but in 
general the PM2.5 annual NAAQS design value is the 
average of three consecutive years annual arithmetic mean 
concentrations, and the PM2.5 24-hour NAAQS design value 
is the average of three consecutive years of the annual 98th 
percentile of 24-hour values.
    \49\ As discussed elsewhere, Texas issued permits to these 
facilities to address emissions during MSS. The permits were not 
submitted as part of this SIP revision. The permits include lb/hour 
and ton/year emission rate limits that are not included in the SIP 
revision and thus are not specifically being reviewed in this action 
but are discussed here as a reference point for the reasonableness 
of Sierra Club's assumptions.
    \50\ We also note that EPA's guidance in assessing 
PM2.5 impacts is to also include the secondary formation 
of PM2.5 due to precursor emissions (i.e. NOX 
and SO2). Including the secondary formation of 
PM2.5 would be expected to have some increase in the 
overall maximum modeled concentration. See Guidance on the 
Development of Modeled Emission Rates for Precursors (MERPs) as a 
Tier 1 Demonstration Tool for Ozone and PM2.5 under the 
PSD Permitting Program (pdf) (3.36 MB, 04/30/2019, 454-R-19-003). 
Available for download at https://www.epa.gov/nsr/guidance-development-modeled-emission-rates-precursors-merps-tier-1-demonstration-tool-ozone
---------------------------------------------------------------------------

    Modeled ambient concentrations are estimated by adding the modeled 
values to a representative background concentration from a 
representative monitor which represents concentrations from non-modeled 
sources and general PM2.5 background levels in the area. 
EPA's review found that Sierra Club used the lowest PM2.5 
monitored design values \51\ in the State of Texas, which are 
significantly lower than PM2.5 monitored design values at 
monitors located closer to these two facilities. Monitored design 
values from these closer monitors should have been added to the 
modeling because they would be more representative of regional 
PM2.5 background concentrations than the low values Sierra 
Club utilized. Using the more representative background monitored 
design value concentrations for Limestone and Martin Lake results in 
higher maximum modeled design values and more of Sierra Club's 
operating scenarios having maximum design values that exceed the 24-
hour and annual PM2.5 NAAQS.
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    \51\ Design Values for PM2.5 Annual and 24-Hour NAAQS 
are calculated in accordance with 40 CFR part 50 Appendix N using 
monitoring data collected and the Design Values are compared to the 
PM2.5 Annual and 24-Hour NAAQS (40 CFR part 50.20) to 
determine whether the design value meets or exceeds the applicable 
PM2.5 NAAQS. See Appendix N for details, but in general 
the PM2.5 annual NAAQS design value is the average of 
three consecutive years annual arithmetic mean concentrations, and 
the PM2.5 24-hour NAAQS design value is the average of 
three consecutive years of the annual 98th percentile of 24-hour 
values.
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    EPA notes that Sierra Club's modeling scenarios were based on both 
boilers at Limestone or the three boilers at Martin Lake having MSS 
emissions at the same time. Those scenarios may not be expected to 
occur often, but the scenario is not limited by the current SIP 
revision or AOs, nor by the MSS permits. The modeling for some of the 
operating scenarios was sufficiently above the NAAQS such that 
additional modeling may show that not all the boilers at a facility 
must have MSS emissions at the same time for modeled violations to 
occur.
    Overall, EPA's review indicates that while there are some 
uncertainties regarding what potential maximum (worst case) MSS 
emission rates should be modeled and that a higher background monitor 
DVs should have been used, the Sierra Club's modeling is informative 
and indicates that PM2.5 MSS emissions allowed under the 
2020 SIP revision and AOs could result in modeled values above the 24-
hour PM2.5 NAAQS and the annual PM2.5 NAAQS. This 
modeling also suggests that a similar modeling analysis of maximum MSS 
emissions from the other power plant facilities at issue here could 
possibly result in violations of the NAAQS because these other 
facilities are similar in the general magnitude of potential hourly MSS 
emissions and have somewhat similar stack parameters (stack velocity, 
temperature and height).

J. Other

1. Change in Facility Operations
    Comment: The commenter (TCEQ) states that four plants (Gibbons 
Creek Steam Electric Station, Pirkey Power Plant, Oklaunion Power 
Station, and Harrington Station) have either ceased burning coal, shut 
down, or converted to natural gas for power generation; therefore, 
making these AOs and their approval into the SIP unnecessary. The 
commenter also states that EPA should approve the other four AOs (Lower 
Colorado River Authority's Sam Seymour Fayette Power Project (order no. 
2020-0077-SIP); Luminant Generation Company, LLC's Martin Lake Steam 
Electric Station (order no. 2020-0076-SIP); NRG Texas Power LLC's 
Limestone Electric Generation

[[Page 104057]]

Station (order no. 2020-0075-SIP); and San Miguel Electric Cooperative, 
Inc.'s San Miguel Electric Plant (order no. 2020-0074-SIP) into the 
SIP.
    Response: TCEQ can formally withdraw the AOs (i.e., a partial 
withdrawal of its submitted SIP revision) that TCEQ believes are no 
longer necessary to be included as part of the Texas SIP. As long as 
the SIP revision is before us, we are legally obligated to act on that 
submission, either by approving or disapproving it. Moreover, we must 
act on the entire SIP revision and cannot parse out pieces and take no 
action. For the reasons described in this final rule and responses to 
other comments, EPA is disapproving Texas's 2020 SIP revision, 
including the accompanying AOs.
2. EPA Comments on the State's Proposed SIP
    Comment: The commenter states that EPA failed to raise concerns 
regarding `legal and practical enforceability,' continuity of the 
limitations, or compliance with AEL guidance during the commission's 
public comment period on the proposed AOs and the 2020 SIP revision. 
The commenter then states that EPA's failure to raise concerns about 
legal and practical enforceability, continuity of the limits, or 
failure to meet certain factors from their AEL guidance indicates EPA 
agreed with TCEQ's assessment that the AOs should be incorporated into 
the SIP.
    Response: EPA disagrees with the commenter's assertion that EPA not 
providing comments during TCEQ's public comment period on its proposed 
SIP regarding concerns about legal and practical enforceability, 
continuity of the limits, or failure to consider certain factors from 
their AEL guidance indicates that EPA agreed with TCEQ's assessment 
that the AOs should be incorporated into the SIP. EPA must follow CAA 
requirements and conduct a formal review of the submitted SIP revision, 
regardless of whether particular objections were raised during a 
proceeding before the SIP was submitted to the Agency.
3. EPA Interpretation of 30 TAC 111
    Comment: The commenters state that EPA repeatedly acknowledged 
TCEQ's interpretation and characterization of its rules in 30 TAC 111, 
including that limits on opacity and PM do not apply during periods of 
SSM for these specific units.
    Response: The commenters misconstrue EPA's statements on TCEQ's 
interpretation and characterization of its rules in 30 TAC 111 as 
acceptance and agreement of its interpretation and characterization. 
While EPA acknowledged TCEQ's interpretation in the proposal, we also 
acknowledged that there is no textual evidence in the rule to provide 
evidence of TCEQ's interpretation. We also point out in other comments 
that this is the first time in a SIP revision that TCEQ has put forward 
this interpretation. The stated goal of this SIP revision was to 
provide continuous federally enforceable emission limitations under 
TCEQ's interpretation that the rules in Chapter 111 do not apply during 
MSS for coal fired electric generating units using ESPs. Without adding 
provisions to the SIP to address time periods of MSS, the requirements 
during MSS and more importantly the duration of time when the chapter 
111 rules would not apply under the TCEQ interpretation will continue 
to be unclear.
4. Misconception of Action as a SIP Call
    Comment: The commenter states that the proposal indicates that 
Texas provisions were previously approved and incorporated into 
operating permits. The commenter cites to CAA section 110(k), stating 
that the CAA imposes a heavy burden of proof for EPA disapproval of an 
already approved SIP revision. The commenter states that EPA has a 
heavy burden of proof to show that previously approved SIP provisions 
are ``substantially inadequate'' to meet the relevant provisions of the 
Act and must be revised, and EPA failed meet this burden and therefore 
must approve the provisions at issue here.
    Response: The commenter appears to mistakenly be stating that EPA 
is proposing disapproval of already approved provisions in the SIP or 
issuing a SIP call under CAA section 110(k)(5). However, the commenter 
also states later that EPA must approve the provisions at issue here. 
EPA is clarifying that (1) EPA did not propose disapproval of an 
already approved SIP revision or propose to find an approved SIP 
provision to be ``substantially inadequate'' and (2) CAA section 
110(k)(5) is not applicable in this context, neither in the proposal or 
this final rule. TCEQ submitted a SIP revision and after our 
evaluation, we proposed disapproval of that SIP revision and its 
provisions as not meeting the requirements of the Act.

III. Final Action

    We are disapproving a revision to the Texas SIP submitted by TCEQ 
on August 20, 2020 (concerning opacity and PM emissions during planned 
MSS activities for certain EGU sources equipped with ESPs as the PM 
control device). These EGUs are the Southwestern Electric Power Company 
(SWEPCO) H.W. Pirkey Power Plant; the Lower Colorado River Authority 
(LCRA) Sam Seymour Fayette Power Project; the Luminant Generation 
Company, LLC Martin Lake Steam Electric Station; the NRG Texas Power, 
LLC Limestone Electric Generating Station; the San Miguel Electric 
Cooperative, Inc. San Miguel Plant; the Southwestern Public Service 
Company (SPS) Harrington Station; the Texas Municipal Power Agency 
(TMPA) Gibbons Creek Steam Electric Station; and the Public Service 
Company of Oklahoma (PSCO) Oklaunion Power Station.
    The Agreed Orders will not be incorporated into the SIP. There will 
be no sanctions or FIP clocks as a result of this action.

IV. Environmental Justice Considerations

    Information on Executive Order 12898 (Federal Actions to Address 
Environmental Justice in Minority Populations and Low-Income 
Populations, 59 FR 7629, February 16, 1994), Executive Order 14096 
(Revitalizing Our Nation's Commitment to Environmental Justice for All, 
88 FR 25251, April 26, 2023), and how EPA defines environmental justice 
(EJ) can be found in the section below titled ``Statutory and Executive 
Order Reviews.'' For informational and transparency purposes only, EPA 
included in its proposal additional analysis of EJ associated with this 
proposed action for the purpose of providing information to the public 
(89 FR 71237).
    Communities in close proximity to and/or downwind of these EGUs may 
be subject to environmental impacts of emissions. Short- and/or long-
term exposure to air pollution has been associated with a wide range of 
human health effects including increased respiratory symptoms, 
hospitalization for heart or lung diseases, and even premature 
death.\52\ Emissions during planned MSS may be higher than emissions 
under normal steady-state operations. The EPA believes that the human 
health or environmental risk addressed by this action will not likely 
have disproportionately high and adverse human health or environmental 
effects on communities with EJ concerns. This action merely disapproves 
a SIP revision as not meeting the CAA requirements. We

[[Page 104058]]

therefore determine that this rulemaking action will not have 
disproportionately high or adverse human health or environmental 
effects on communities with EJ concerns.
---------------------------------------------------------------------------

    \52\ See https://www.epa.gov/air-quality-management-process/managing-air-quality-human-health-environmental-and-economic#what 
(accessed dated 02/05/2024).
---------------------------------------------------------------------------

V. Statutory and Executive Order Reviews

    Under the Act, the Administrator is required to approve a SIP 
submission that complies with the provisions of the Act and applicable 
Federal regulations.\53\ Thus, in reviewing SIP submissions, EPA's role 
is to approve State choices, provided that they meet the criteria of 
the Act. Accordingly, this action disapproves Texas's 2020 SIP revision 
as not meeting applicable requirements of the CAA.
---------------------------------------------------------------------------

    \53\ 42 U.S.C. 7410(k); 40 CFR 52.02(a).
---------------------------------------------------------------------------

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review, Executive 
Order 13563: Improving Regulation and Regulatory Review, and Executive 
Order 14094: Modernizing Regulatory Review

    This action is not a significant regulatory action as defined in 
Executive Order 12866 (58 FR 51735, October 4, 1993), as amended by 
Executive Order 14094 (88 FR 21879, April 11, 2023), and was therefore 
not subject to a requirement for Executive Order 12866 review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA (44 U.S.C. 3501 et seq.) because it does not contain any 
information collection activities.

C. Regulatory Flexibility Act (RFA)

    This action is certified to not have a significant economic impact 
on a substantial number of small entities under the RFA (5 U.S.C. 601 
et seq.). This action will not impose any requirements on small 
entities.

D. Unfunded Mandates Reform Act (UMRA)

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

E. Executive Order 13132: Federalism

    This action does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999). It will not have 
substantial direct effects on the States, on the relationship between 
the national government and the States, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Coordination With Indian Tribal Governments

    This action has no Tribal implications as specified in E.O. 13175 
(65 FR 67249, November 9, 2000). This action will neither impose 
substantial direct compliance costs on federally recognized Tribal 
governments, nor preempt Tribal law. This action will not impose 
substantial direct compliance costs on federally recognized Tribal 
governments because no actions will be required of Tribal governments. 
This action will also not preempt Tribal law as it does not have 
applicable or related Tribal laws.

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

    EPA interprets Executive Order 13045 (62 FR 19885, April 23, 1997) 
as applying only to those regulatory actions that concern environmental 
health or safety risks that EPA has reason to believe may 
disproportionately affect children, per the definitions of ``covered 
regulatory action'' in section 2-202 of the Executive Order. Therefore, 
this action is not subject to Executive Order 13045 because it merely 
disapproves a SIP revision. Furthermore, the EPA's Policy on Children's 
Health does not apply to this action.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 (66 FR 28355, 
May 22, 2001), because it is not a significant regulatory action under 
Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the NTTAA directs the EPA to use voluntary 
consensus standards in its regulatory activities unless to do so would 
be inconsistent with applicable law or otherwise impractical. This 
action is not subject to the requirements of section 12(d) of the NTTAA 
(15 U.S.C. 272 note) because application of those requirements would be 
inconsistent with the CAA.

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

    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 16, 1994) directs Federal agencies to identify and address 
``disproportionately high and adverse human health or environmental 
effects'' of their actions on communities with environmental justice 
(EJ) concerns to the greatest extent practicable and permitted by law. 
Executive Order 14096 (Revitalizing Our Nation's Commitment to 
Environmental Justice for All, 88 FR 25251, April 26, 2023) builds on 
and supplements E.O. 12898 and defines EJ as, among other things, ``the 
just treatment and meaningful involvement of all people, regardless of 
income, race, color, national origin, or Tribal affiliation, or 
disability in agency decision-making and other Federal activities that 
affect human health and the environment.''
    The air agency did not evaluate environmental justice 
considerations as part of its 2020 SIP revision; the CAA and applicable 
implementing regulations neither prohibit nor require such an 
evaluation. The EPA performed an environmental justice analysis, as is 
described above in the section titled, ``Environmental Justice 
Considerations.'' The analysis was done for the purpose of providing 
additional context and information about this rulemaking to the public, 
not as a basis of the action. Due to the nature of the action being 
taken here, this action is expected to have no impact on the air 
quality of the affected area. In addition, there is no information in 
the record upon which this decision is based inconsistent with the 
stated goal of E.O. 12898 of achieving environmental justice for 
communities with EJ concerns.
    This action is subject to the Congressional Review Act, 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).
    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by February 18, 2025. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this action for the purposes of 
judicial review nor does it extend the time

[[Page 104059]]

within which a petition for judicial review may be filed, and shall not 
postpone the effectiveness of such rule or action. This action may not 
be challenged later in proceedings to enforce its requirements. (See 
section 307(b)(2).)

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Carbon monoxide, 
Hydrocarbons, Incorporation by reference, Intergovernmental relations, 
Lead, Nitrogen dioxide, Particulate matter, Sulfur dioxide, Reporting 
and recordkeeping requirements, Volatile organic compounds.

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

    Dated: December 12, 2024.
Earthea Nance,
Regional Administrator, Region 6.
[FR Doc. 2024-29956 Filed 12-19-24; 8:45 am]
BILLING CODE 6560-50-P
```