Air Plan Disapproval; Texas; Control of Air Pollution From Visible Emissions and Particulate Matter, 104043-104059 [2024-29956]
Download as PDF
Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations
■ 3. Amend § 4044.58 by revising table
1 to § 4044.58 to read as follows:
104043
§ 4044.58 Tables used to determine
expected retirement age.
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TABLE 1 TO § 4044.58—TABLE I–25—SELECTION OF RETIREMENT RATE CATEGORY
[For valuation dates in 2025 1]
Participant’s retirement rate category is—
If participant
reaches URA in
year—
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
Medium 3 if monthly benefit
at URA is—
Low 2 if monthly
benefit at URA
is less than—
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
.........................................................................................
or later ............................................................................
From—
825
844
864
884
904
925
946
968
990
1,013
High 4 if monthly
benefit at URA is
greater than—
To—
825
844
864
884
904
925
946
968
990
1,013
3,486
3,566
3,648
3,732
3,818
3,906
3,996
4,088
4,182
4,278
3,486
3,566
3,648
3,732
3,818
3,906
3,996
4,088
4,182
4,278
1 Applicable
tables for valuation dates before 2025 are available on PBGC’s website (www.pbgc.gov).
II–A.
II–B.
4 Table II–C.
2 Table
3 Table
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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.
*
Issued in Washington, DC.
Hilary Duke,
Assistant General Counsel for Regulatory
Affairs Pension Benefit Guaranty
Corporation.
[FR Doc. 2024–29105 Filed 12–19–24; 8:45 am]
BILLING CODE 7709–02–P
ENVIRONMENTAL PROTECTION
AGENCY
This rule is effective on January
21, 2025.
DATES:
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
Environmental Protection
Agency (EPA).
ACTION: Final rule.
AGENCY:
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)
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SUMMARY:
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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.
ADDRESSES:
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,
Feldman.Michael@epa.gov. Please call
or email the contact listed above if you
need alternative access to material
indexed but not provided in the docket.
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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
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.
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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.
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
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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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
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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
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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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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
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.
4 Basic Information About Air Quality SIPs,
https://www.epa.gov/air-quality-implementationplans/basic-information-about-air-quality-sips (last
updated January 20, 2023).
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applicable CAA requirements for that
particular submission, which can vary
based on program requirements and the
relevant NAAQS.
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.
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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
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
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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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.
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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
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
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in Environ. Comm. Fl. Elec. Power v.
EPA, 94 F.4th at 93:
limits apply on a continuous basis to assure
continuous emission reduction).
[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 Elec. Co., 427
U.S. at 256–57).
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.
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.
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
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 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,
§ 110(a)(2)(A)—SIP must contain emission
limits, measures, etc. and § 302(k)—emission
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.
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.’’
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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
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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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.
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
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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statutory definition of an ‘emission
limitation.’ ’’ 10
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
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,
§ 110(a)(2)(A)—SIP must contain emission
limits, measures, etc. and § 302(k)—emission
limits apply on a continuous basis to assure
continuous emission reduction).14
10 94
F.4th at 102.
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.’’
14 2020 SIP revision at iv.
11 Id.
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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.
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
15 94
F.4th at 107.
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,
16 CAA
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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
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.
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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 ‘‘nonapplicability’’ 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
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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.
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
18 57
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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.
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, ‘‘nonapplicability’’ 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
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.
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
§§ 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.
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a ‘‘semantic ‘gotcha’ game.’’ Florida
Electric, 94 F.4th at 109.
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
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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
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.
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.
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.
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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 controllevel 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
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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
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.
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
23 See
Section II.C and D
Guidance an Enforceability Requirements
for Limiting Potential to Emit through SIP and § 112
Rules and General Permits, US EPA, January 25,
1995.
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).
24 See
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source’s election to be covered by the
rule; and (6) recognize the enforcement
consequences relevant to the rule.26
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.
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
26 Id.
27 See source specific AOs included in the docket
for this action.
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
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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
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 mg/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 mg/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.
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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.
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
30 See
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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.
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
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.
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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.
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
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.
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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
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
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.
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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
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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.
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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 °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
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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
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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
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
34 We fully address these late comments in the
RTC document.
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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 subbituminous 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 subbituminous 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 emissionsreducing measures in the SIP. In
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
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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.’’
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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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
39 There are PM
2.5 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.
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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
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.
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 SO designations FR cities including Federal
2
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)
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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
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
Response: The EPA obtained the
modeling files from Sierra Club (SC) and
has reviewed both the reports from
Wingra (Sierra Club’s contractor) and
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.
47 We fully address these late comments from
NRG and Luminant in the RTC document.
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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
ddrumheller on DSK120RN23PROD with RULES1
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 mg/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 mg/m3.’’ 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
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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
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
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-developmentmodeled-emission-rates-precursors-merps-tier-1demonstration-tool-ozone
51 Design Values for PM
2.5 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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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.
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
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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.
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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
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14:50 Dec 19, 2024
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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
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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
52 See https://www.epa.gov/air-qualitymanagement-process/managing-air-quality-humanhealth-environmental-and-economic#what
(accessed dated 02/05/2024).
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therefore determine that this rulemaking
action will not have disproportionately
high or adverse human health or
environmental effects on communities
with EJ concerns.
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.
Additional information about these
statutes and Executive Orders can be
found at https://www.epa.gov/lawsregulations/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 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.
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.
D. Unfunded Mandates Reform Act
(UMRA)
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F. Executive Order 13175: Coordination
With Indian Tribal Governments
H. Executive Order 13211: Actions That
Significantly Affect Energy Supply,
Distribution, or Use
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.
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,
53 42
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.
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.
U.S.C. 7410(k); 40 CFR 52.02(a).
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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
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Federal Register / Vol. 89, No. 245 / Friday, December 20, 2024 / Rules and Regulations
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
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R04–OAR–2023–0501; FRL–12273–
01–R4]
Air Plan Approval; Georgia; Update to
Materials Incorporated by Reference
Environmental Protection
Agency (EPA).
ACTION: Final rule; notification of
administrative change.
AGENCY:
The Environmental Protection
Agency (EPA) is updating the materials
that are incorporated by reference (IBR)
into the Georgia State Implementation
Plan (SIP). The regulations affected by
this update have been previously
submitted by Georgia and approved by
EPA. In this notice, EPA is also
notifying the public of corrections to the
Code of Federal Regulations (CFR)
tables that identify material
incorporated by reference into the
Georgia SIP. This update affects the
materials that are available for public
inspection at the National Archives and
Records Administration (NARA) and the
EPA Regional Office.
DATES: This action is effective December
20, 2024.
ADDRESSES: The SIP materials whose
incorporation by reference into 40 CFR
part 52 is finalized through this action
are available for inspection at the
following locations: Environmental
Protection Agency, Region 4, 61 Forsyth
Street SW, Atlanta, GA 30303; and
www.regulations.gov. To view the
materials at the Region 4 Office, EPA
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SUMMARY:
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requests that you email the contact
listed in the FOR FURTHER INFORMATION
CONTACT section to schedule your
inspection. The Regional Office’s
official hours of business are Monday
through Friday 8:30 a.m. to 4:30 p.m.,
excluding Federal holidays.
FOR FURTHER INFORMATION CONTACT:
Josue Ortiz Borrero, Air Regulatory
Management Section, Air Planning and
Implementation Branch, Air and
Radiation Division, U.S. Environmental
Protection Agency, Region 4, 61 Forsyth
Street SW, Atlanta, Georgia 30303–8960.
Mr. Josue Ortiz Borrero can be reached
via telephone at (404) 562–8085 or via
electronic mail at ortizborrero.josue@
epa.gov.
SUPPLEMENTARY INFORMATION:
I. Background
Each State has a SIP containing the
control measures and strategies used to
attain and maintain the national
ambient air quality standards (NAAQS).
The SIP is extensive, containing such
elements as air pollution control
regulations, emission inventories,
monitoring networks, attainment
demonstrations, and enforcement
mechanisms.
Each State must formally adopt the
control measures and strategies in the
SIP after the public has had an
opportunity to comment on them and
then submit the proposed SIP revisions
to EPA. Once these control measures
and strategies are approved by EPA, and
after notice and comment, they are
incorporated into the federallyapproved SIP and are identified in part
52, ‘‘Approval and Promulgation of
Implementation Plans,’’ title 40 of the
Code of Federal Regulations (40 CFR
part 52). The full text of the State
regulation approved by EPA is not
reproduced in its entirety in 40 CFR part
52 but is ‘‘incorporated by reference.’’
This means that EPA has approved a
given State regulation or specified
changes to the given regulation with a
specific effective date. The public is
referred to the location of the full text
version should they want to know
which measures are contained in a
given SIP. The information provided
allows EPA and the public to monitor
the extent to which a State implements
a SIP to attain and maintain the NAAQS
and to take enforcement action for
violations of the SIP.
The SIP is a living document which
the State can revise as necessary to
address the unique air pollution
problems in the State. Therefore, EPA
from time to time must take action on
proposed revisions containing new or
revised State regulations. A submission
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104059
from a State can revise one or more
rules in their entirety or portions of
rules. The State indicates the changes in
the submission (such as by using
redline/strikethrough text) and EPA
then takes action on the requested
changes. EPA establishes a docket for its
actions using a unique Docket
Identification Number, which is listed
in each action. These dockets and the
complete submission are available for
viewing on www.regulations.gov.
On May 22, 1997 (62 FR 27968), EPA
revised the procedures for incorporating
by reference, into the Code of Federal
Regulations, materials approved by EPA
into each SIP. These changes revised the
format for the identification of the SIP
in 40 CFR part 52, streamlined the
mechanisms for announcing EPA
approval of revisions to a SIP, and
streamlined the mechanisms for EPA’s
updating of the IBR information
contained for each SIP in 40 CFR part
52. The revised procedures also called
for EPA to maintain ‘‘SIP Compilations’’
that contain the federally approved
regulations and source-specific permits
submitted by each State agency.
EPA generally updates these SIP
Compilations on an annual basis. Under
the revised procedures, EPA must
periodically publish an informational
document in the rules section of the
Federal Register notifying the public
that updates have been made to a SIP
Compilation for a particular State. EPA
began applying the 1997 revised
procedures to Georgia on May 21, 1999,
see 64 FR 27699, and is providing this
notification in accordance with such
procedures.
II. EPA Action
In this action, EPA is providing notice
of an update to the materials
incorporated by reference into the
Georgia SIP as of September 1, 2024,
and identified in 40 CFR 52.570(c). This
update includes SIP materials submitted
by Georgia and approved by EPA since
the last IBR update. See 88 FR 16564
(March 20, 2023). In addition, EPA is
providing notice of the following
corrections to 40 CFR 52.570(c):
Changes Applicable to Paragraph (c),
Table (1), EPA-Approved Georgia
Regulations
A. Under 391–3–1–.02(7), ‘‘Prevention
of Significant Deterioration of Air
Quality (PSD),’’ the explanation column
is reformatted to combine the two
existing paragraphs into one cell.
B. Under 391–3–1–.01, ‘‘Definitions,’’
the explanation column is revised to
add the text ‘‘which were’’ before the
text ‘‘approved on 12/4/2018’’ and
before the text ‘‘approved on 2/2/1996,’’
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Agencies
[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.
-----------------------------------------------------------------------
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.
---------------------------------------------------------------------------
\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).
---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------
\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.
---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------
\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).
---------------------------------------------------------------------------
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\
---------------------------------------------------------------------------
\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.
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------
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.
---------------------------------------------------------------------------
\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).
---------------------------------------------------------------------------
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\
---------------------------------------------------------------------------
\10\ 94 F.4th at 102.
---------------------------------------------------------------------------
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\
---------------------------------------------------------------------------
\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.''
---------------------------------------------------------------------------
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\
---------------------------------------------------------------------------
\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.
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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\
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\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.
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\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.
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[[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\
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\23\ See Section II.C and D
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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.
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\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.
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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\
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\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.
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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.
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\27\ See source specific AOs included in the docket for this
action.
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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.
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\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.
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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.
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\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.
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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.
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\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.
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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\
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\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\
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\34\ We fully address these late comments in the RTC document.
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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.''
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\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
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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\
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\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)
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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\
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\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\
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\47\ We fully address these late comments from NRG and Luminant
in the RTC document.
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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\
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\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
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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.
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\52\ See https://www.epa.gov/air-quality-management-process/managing-air-quality-human-health-environmental-and-economic#what
(accessed dated 02/05/2024).
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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.
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\53\ 42 U.S.C. 7410(k); 40 CFR 52.02(a).
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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