[Federal Register Volume 87, Number 101 (Wednesday, May 25, 2022)]
[Proposed Rules]
[Pages 31798-31814]
[FR Doc No: 2022-10765]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2022-0347; FRL-9333-01-R3]

Federal Implementation Plan Addressing Reasonably Available
Control Technology Requirements for Certain Sources in Pennsylvania

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing a
Federal implementation plan (FIP) for the Commonwealth of Pennsylvania
(Pennsylvania or the Commonwealth). This FIP proposes to set emission
limits for nitrogen oxides (NOX) emitted from coal-fired
electric generating units (EGUs) equipped with selective catalytic
reduction (SCR) in order to meet the reasonably available control
technology (RACT) requirements for the 1997 and 2008 ozone national
ambient air quality standards (NAAQS). The FIP is being proposed to
ensure that EPA can, if necessary, meet a court-ordered deadline
requiring EPA to approve an amended State Implementation Plan (SIP) or
issue a FIP by August 27, 2022. This action is being taken under the
Clean Air Act (CAA).

DATES: Comments must be received by July 11, 2022.
    Public hearing: EPA will hold a virtual public hearing on June 9,
2022. Please refer to the SUPPLEMENTARY INFORMATION section for
additional information on the public hearing.

ADDRESSES: You may send comments, identified by Docket ID No. EPA-R03-
OAR-2022-0347; via the Federal eRulemaking Portal: https://www.regulations.gov/ (our preferred method). Follow the online
instructions for submitting comments.
    Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document. Out
of an abundance of caution for members of the public and our staff, the
EPA Docket Center and Reading Room are open to the public by
appointment only to reduce the risk of transmitting COVID-19. Our
Docket Center staff also continues to provide remote customer service
via email, phone, and webform. Hand deliveries and couriers may be
received by scheduled appointment only. For further information on EPA
Docket Center services and the current status, please visit us online
at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: David Talley, Permits Branch (3AD10),
Air & Radiation Division, U.S. Environmental Protection Agency, Region
III, 1650 Arch Street, Philadelphia, Pennsylvania 19103. The telephone
number is<PHONE_NUMBER>. Mr. Talley can also be reached via electronic
mail at [email protected].

SUPPLEMENTARY INFORMATION:

I. Public Participation

A. Written Comments

    Submit your comments, identified by Docket ID No. EPA-R03-OAR-2022-
0347 at https://www.regulations.gov (our preferred method), or the
other methods identified in the ADDRESSES section. Once submitted,
comments

cannot be edited or removed from the docket. EPA may publish any
comment received to its public docket. Do not submit to EPA's docket at
https://www.regulations.gov any information you consider to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system). For
additional submission methods, the full EPA public comment policy,
information about CBI or multimedia submissions, and general guidance
on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Due to public health concerns related to COVID-19, EPA Docket
Center and Reading Room are open to the public by appointment only. Our
Docket Center staff also continues to provide remote customer service
via email, phone, and webform. Hand deliveries or couriers will be
received by scheduled appointment only. For further information and
updates on EPA Docket Center services, please visit us online at
https://www.epa.gov/dockets.
    EPA continues to carefully and continuously monitor information
from the Centers for Disease Control and Prevention (CDC), local area
health departments, and our Federal partners so that we can respond
rapidly as conditions change regarding COVID-19.

B. Participation in Virtual Public Hearing

    Please note that because of current CDC recommendations, as well as
state and local orders for social distancing to limit the spread of
COVID-19, EPA cannot hold in-person public meetings at this time.
    EPA will begin pre-registering speakers for the hearing no later
than 1 business day after publication of this document in the Federal
Register. To register to speak at the virtual hearing, please use the
online registration form available at https://www.epa.gov/pa/epa-meetings-and-events-pennsylvania. The last day to pre-register to speak
at the hearing will be June 6, 2022. EPA will post a general agenda for
the hearing that will list pre-registered speakers in approximate order
at: https://www.epa.gov/pa/epa-meetings-and-events-pennsylvania.
    The virtual public hearing will be held via teleconference on June
9, 2022. The virtual public hearing will convene at 4 p.m. Eastern Time
(ET) and will conclude at 7 p.m. ET. EPA may close a session 15 minutes
after the last pre-registered speaker has testified if there are no
additional speakers. For information or questions about the public
hearing, please contact Ms. Karen Delgrosso at [email protected].
EPA will announce further details at https://www.epa.gov/pa/epa-meetings-and-events-pennsylvania.
    EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule.
    Each commenter will have 5 minutes to provide oral testimony. EPA
encourages commenters to provide EPA with a copy of their oral
testimony electronically (via email) by emailing it to
[email protected]. EPA also recommends submitting the text of
your oral comments as written comments to the rulemaking docket.
    EPA may ask clarifying questions during the oral presentations, but
will not respond to the presentations at that time. Written statements
and supporting information submitted during the comment period will be
considered with the same weight as oral comments and supporting
information presented at the public hearing.
    Please note that any updates made to any aspect of the hearing will
be posted online at https://www.epa.gov/pa/epa-meetings-and-events-pennsylvania. While EPA expects the hearing to go forward as set forth
above, please monitor our website or contact Ms. Karen Delgrosso at
[email protected] to determine if there are any updates. EPA does
not intend to publish a document in the Federal Register announcing
updates.
    If you require the services of a translator or special
accommodations such as audio description, please pre-register for the
hearing and describe your needs by June 6, 2022. EPA may not be able to
arrange accommodations without advanced notice.

II. Background

A. RACT Requirements for Ozone

    The CAA regulates emissions of NOX and volatile organic
compounds (VOC) to prevent photochemical reactions that result in ozone
formation. RACT is an important requirement for reducing NOX
and VOC emissions from major stationary sources and sources covered by
EPA's control technique guidelines (CTG). Areas designated
nonattainment for the ozone NAAQS are subject to section 182(b)(2) of
the CAA which sets forth RACT requirements specific to ozone
nonattainment areas classified as Moderate nonattainment or higher.
    Specifically, section 182(b)(2) of the CAA sets forth three
distinct requirements regarding RACT for the ozone NAAQS. First,
section 182(b)(2)(A) requires states with ozone nonattainment areas
designated Moderate or higher to submit a RACT rule (or negative
declaration) for each category of VOC sources in the area covered by a
CTG document issued by EPA between November 15, 1990, and the date of
attainment for an ozone NAAQS. Second, section 182(b)(2)(B) requires a
RACT rule (or negative declaration) for all VOC sources in the
nonattainment area covered by any CTG issued before November 15, 1990.
Third, section 182(b)(2)(C) requires a RACT rule or rules (or negative
declaration) for any other major stationary sources of VOCs located in
the nonattainment area.
    In addition, section 182(f) subjects major stationary sources of
NOX to the same RACT requirements that are applicable to
major stationary sources of VOC. Therefore, the RACT requirement for
major stationary sources found in 182(b)(2)(C) applies to sources of
NOX. A ``major source'' for purposes of RACT applicability
in section 182 is defined based on the source's potential to emit (PTE)
of NOX, VOC, or both pollutants, and the applicable
thresholds are defined based on the classification of the nonattainment
area in which the source is located. See sections 182(c)-(f) and 302 of
the CAA. The ozone RACT requirements under section 182(b)(2) are
usually referred to as VOC CTG RACT, non-CTG major VOC RACT, and major
NOX RACT.\1\
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    \1\ This proposed FIP pertains only to the major NOX
RACT requirements for Pennsylvania's coal-fired EGUs already
equipped with SCR (five facilities in total).
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    Section 184(a) of the CAA, which was added by the 1990 Amendments
to the CAA, established an Ozone Transport Region (the OTR) comprised
of all or parts of 12 eastern states, and the District of Columbia,
including all of Pennsylvania.\2\ Section 184(b)(1)(B) extends the VOC
CTG RACT requirements in section 182(b)(2)(A) and (B) to all areas in
the OTR regardless of NAAQS attainment status. Put another way, because
the entire State of Pennsylvania is in the OTR, the requirements of CAA
section 184 apply statewide even if all areas of the State were
attaining the ozone NAAQS. Further, section 184(b)(2) states that

``any stationary source that emits or has the potential to emit at
least 50 tons per year (TPY) of volatile organic compounds shall be
considered a major stationary source and subject to the requirements
which would be applicable to major stationary sources if the area were
classified as a Moderate nonattainment area.'' This language applies
the RACT requirement of 182(b)(2)(C) to all stationary sources in the
OTR that have a PTE of at least 50 TPY of VOC. The EPA further
clarified in 1992 that for purposes of applying section 182(f)
requirements to NOX sources in the OTR, and certain other
areas, a major stationary source for purposes of NOX RACT
applicability will be defined as any stationary source in the OTR that
emits or has the potential to emit 100 tons per year or more of
NOX.\3\ In total, these RACT requirement in section 184 are
referred to as ``OTR RACT.''
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    \2\ https://www3.epa.gov/region1/airquality/noxract.html.
    \3\ See ``State Implementation Plans; Nitrogen Oxides Supplement
to the General Preamble for the Implementation of Title I of the
Clean Air Act Amendments of 1990,'' 57 FR 55620, 55622 (November 25,
1992).
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    Since the 1970's, EPA has consistently defined RACT as ``the lowest
emission limit that a particular source is capable of meeting by the
application of the control technology that is reasonably available
considering technological and economic feasibility.'' \4\ Since then,
EPA has provided more substantive information on RACT requirements
through implementation rules for each ozone NAAQS, and has issued
additional guidance documents on RACT.\5\ In 2004 and 2005, EPA
promulgated an implementation rule for the 1997 8-hour ozone NAAQS in
two phases: ``Phase 1 of the 1997 Ozone Implementation Rule;'' and
``Phase 2 of the 1997 Ozone Implementation Rule.'' See 69 FR 23951
(April 30, 2004) and 70 FR 71612 (November 29, 2005), respectively.
Particularly, the Phase 2 Ozone Implementation Rule addressed RACT
statutory requirements under the 1997 8-hour ozone NAAQS. See 70 FR
71652.
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    \4\ Memo, dated December 9, 1976, from Roger Strelow, Assistant
Administrator for Air and Waste Management, to Regional
Administrators, ``Guidance for Determining Acceptability of SIP
Regulations in Non-Attainment Areas,'' p. 2, available at https://www3.epa.gov/ttn/naaqs/aqmguide/collection/cp2/19761209_strelow_ract.pdf and 44 FR 53762, footnote 2 (September 17,
1979) (Strelow Memo).
    \5\ Additional guidance includes the General Preamble for the
Implementation of Title I of the Clean Air Act Amendments of 1990
(1992 General Preamble), 57 FR 13498 (April 16, 1992), and the
General Preamble for the Implementation of Title I of the Clean Air
Act Amendments of 1990; Supplemental Appendices to the General
Preamble, 57 FR 18070 (April 28, 1992). See also https://www.epa.gov/ground-level-ozone-pollution/ract-information.
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    On March 6, 2015, EPA issued its final rule for implementing the
2008 8-hour ozone NAAQS (the ``2008 Ozone SIP Requirements Rule''). See
80 FR 12264. At the same time, EPA revoked the 1997 8-hour ozone NAAQS,
effective on April 6, 2015. The 2008 Ozone SIP Requirements Rule
provided comprehensive requirements related to the revoked 1997 8-hour
ozone NAAQS, codified in 40 CFR part 51, subpart AA. EPA determined
that areas designated nonattainment for both the 1997 and 2008 8-hour
ozone NAAQS at the time the 1997 8-hour ozone NAAQS was revoked retain
certain nonattainment area requirements (i.e. anti-backsliding
requirements) for the 1997 8-hour ozone NAAQS, including RACT. See 40
CFR 51.1105(a)(1); 51.1100(o). Pennsylvania is also required to
implement certain RACT requirements statewide since the entirety of the
state is in the OTR. CAA section 184(b). Thus, all of Pennsylvania
remains subject to RACT requirements for both the 1997 8-hour ozone
NAAQS and the 2008 8-hour ozone NAAQS.

B. Applicability of RACT Requirements in Pennsylvania

    As indicated previously, RACT requirements apply to any ozone
nonattainment areas classified as Moderate or higher (Serious, Severe,
or Extreme) under CAA sections 182(b)(2). Pennsylvania has a number of
areas that are designated nonattainment for the 2008 8-hour ozone
NAAQS, including Allegheny and Armstrong Counties. Some areas are
additionally required to implement RACT nonattainment requirements as
anti-backsliding measures for the revoked 1997 8-hour NAAQS. Also, the
entire Commonwealth of Pennsylvania is part of the OTR established
under section 184 of the CAA and thus subject statewide to the RACT
requirements of CAA sections 182(b)(2) and 182(f), pursuant to section
184(b). While RACT must be evaluated and satisfied as separate
requirements under each applicable standard, in practice the same RACT
requirements are applicable at this time in Pennsylvania for both the
1997 and 2008 8-hour ozone NAAQS.
    States were required to make RACT SIP submissions for the 1997 8-
hour ozone NAAQS by September 15, 2006. The Pennsylvania Department of
Environmental Protection (PADEP) submitted a SIP revision on September
25, 2006, certifying that a number of previously approved VOC CTG and
non-CTG major VOC RACT rules continued to satisfy RACT under the 1997
8-hour ozone NAAQS. EPA approved PADEP's September 25, 2006 submittal,
so those requirements are not addressed in this action. See 82 FR 31464
(July 7, 2017). RACT control measures addressing all applicable CAA
requirements under the 1997 8-hour ozone NAAQS have been implemented
and fully approved in the jurisdictions of Allegheny County and
Philadelphia County in Pennsylvania and are also not addressed here.
See 78 FR 34584 (June 10, 2013) and 81 FR 69687 (October 7, 2016). For
the 2008 8-hour ozone NAAQS, states were required to submit RACT SIP
revisions by July 20, 2014.

C. Pennsylvania RACT Regulatory History, Legal Challenges and Partial
Disapproval

    On May 16, 2016, PADEP submitted a SIP revision addressing RACT
under both the 1997 and 2008 8-hour ozone NAAQS in Pennsylvania.
Specifically, the May 16, 2016 SIP submittal intended to satisfy
sections 182(b)(2)(C), 182(f), and 184 of the CAA for both the 1997 and
2008 8-hour ozone NAAQS for Pennsylvania's major NOX and
non-CTG major VOC sources, with a few exceptions not relevant to this
action. PADEP's SIP revision included newly adopted regulations found
at 25 Pennsylvania Code (Pa. Code) sections 129.96-129.100, titled
``Additional RACT Requirements for Major Sources of NOX and
VOCs'' (the RACT II Rule) and amendments to 25 Pa. Code section 121.1,
including related definitions, to be incorporated into the Pennsylvania
SIP. These regulatory amendments were adopted by PADEP on April 23,
2016, and became effective on the same date upon publication in the
Pennsylvania Bulletin.
    On May 9, 2019, EPA published a final action fully approving
certain provisions of PADEP's RACT II rule, and conditionally approving
other provisions of the SIP revision. 84 FR 20274 (May 9, 2019). The
Sierra Club commented on EPA's proposed approval of the RACT II rule,
and following EPA's final approval, filed a petition for review with
the U.S. Third Circuit Court of Appeals (Third Circuit). The petition
challenged EPA's approval of only that portion of the RACT II rule
applicable to coal-fired EGUs equipped with SCR for control of
NOX. Specifically, the petition challenged EPA's approval of
the presumptive RACT NOX limit for these EGUs of 0.12 pounds
(lb) of NOX per one million British thermal units (MMBtu) of
heat input (lb/MMBtu) when the inlet temperature to the SCR was 600
degrees Fahrenheit or above, found at 25 Pa. Code 129.97(g)(1)(viii);
the application of the less stringent NOX limits of 25 Pa.

Code 129.97(g)(1)(vi) to EGUs with SCR when the inlet temperature to
the SCR was below 600 degrees Fahrenheit; \6\ and the failure of the
RACT II rule at 25 Pa. Code 129.100(d) to specifically require these
EGUs to record temperature data for the inlet temperature to the SCRs
and report that data to PADEP. At the time of EPA's approval, there
were six facilities in Pennsylvania which were subject to the portion
of the RACT II rule which was relevant for purposes of the legal
challenge: Bruce Mansfield Generating Station in Beaver County (Bruce
Mansfield), Cheswick Generating Station in Allegheny County (Cheswick),
Conemaugh Generating Station in Indiana County (Conemaugh), Homer City
Generating Station in Indiana County (Homer City), Keystone Generating
Station in Armstrong County (Keystone), and Montour Generating Station
in Montour County (Montour). Subsequently, Bruce Mansfield ceased
operations and surrendered their title V operating permit, and
therefore is not included in this action. Additionally, Cheswick
Generating Station was issued a title V modification which included an
enforceable requirement to cease operations on or before April 1,
2022.\7\ Because the process of closure is still ongoing during
development of this proposed rulemaking action, EPA cannot
affirmatively determine at this time that operations at Cheswick have
permanently and enforceably ceased. Therefore, EPA is proposing RACT
limits for Cheswick. If operations have permanently and enforceably
ceased prior to a final rulemaking action, EPA will not finalize RACT
limits for Cheswick.
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    \6\ 25 Pa Code 129.97(g)(1)(vi) applies to coal-fired combustion
units with a heat input greater than 250 million MMBtu/hr that do
not have SCR.
    \7\ Documentation for both closures is contained in the docket
for this action.
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    On August 27, 2020, the Third Circuit Court of Appeals found for
the Sierra Club on all three issues, vacated the Agency's approval of
the SIP submission on each of these three pieces of the Pennsylvania
plan as it pertained to coal-fired EGUs equipped with SCRs (which was
applicable to the six facilities listed above), and remanded to the
Agency.\8\ Sierra Club v. EPA, 972 F.3d 290 (3rd Cir. 2020) (Sierra
Club). The court held that EPA's approval of 25 Pa. Code
129.97(g)(1)(viii) was arbitrary and capricious because the record did
not support EPA's finding that the emission rate limit of 0.12 lb/MMBtu
was RACT for these EGU sources, particularly in light of submitted
evidence that EGUs in Pennsylvania regulated by 25 Pa. Code
129.97(g)(1)(viii) had achieved much lower emission rates for
NOX in the past, and that other states had adopted lower
RACT NOX limits for coal-fired sources. Sierra Club at 299-
303. In addition, the court held that EPA's approval of the less
stringent limits (found in 25 Pa Code 129.97(g)(1)(vi)) when the inlet
temperature fell below 600-degrees Fahrenheit was arbitrary and
capricious because the record failed to support the need for that less
stringent limit or explain why 600 degrees was chosen as the threshold
for the change in limits. Id. at 303-307. Thus, the court vacated EPA's
approval of the 0.12 lb/MMBtu limit, and the 600-degree temperature
threshold, both of which are only found in 25 Pa. Code
129.97(g)(1)(viii).\9\ See Id. at 309.
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    \8\ Those portions of the SIP which were not subject to
challenge in litigation remain approved by EPA's May 2019 action.
    \9\ The court did not vacate 25 Pa Code 129.97(g)(1)(vi)
generally. The court took issue with 25 Pa Code 129.97(g)(1)(vi)
only as it was being applied to EGUs with SCR when the inlet
temperature to the SCR was below 600 degrees Fahrenheit.
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    Regarding the reporting and record keeping requirement of 25 Pa.
Code 129.100(d), the court also found EPA's approval of the specific
SIP revisions discussed above to be arbitrary and capricious based upon
the lack of a specific record keeping and reporting requirement for the
600-degree inlet temperature alternative limits to the SCR. See Id.
Specifically, the court held that ``[b]ecause the SIP's 600-degree
threshold necessarily depends upon accurate temperature reporting, the
EPA's approval of such inadequate requirements on this record was
arbitrary and capricious.'' Id. at 309. Lacking evidence in the record
that more general recordkeeping and reporting requirements contained in
the SIP would require sources subject to 25 Pa. Code 129.97(g)(1)(viii)
to keep specific SCR temperature inlet data, report that data to PADEP,
and make it available to the public, the court agreed with the Sierra
Club. Id. at 308. Further, the court explained that ``[t]he combination
of this lack of mandatory reporting and the temperature waiver created
a potent loophole for polluters to walk through.'' Id. at 297.
    The court further stated that ``[o]n remand, the agency must either
approve a revised, compliant SIP within two years or formulate a new
federal implementation plan.'' Id. at 309. On September 15, 2021, EPA
proposed disapproval of those portions of the prior approval which were
vacated by the Court. See 86 FR 51315. EPA proposed that action in part
to ensure that we have authority to promulgate a FIP if Pennsylvania
does not submit a timely approvable SIP revision addressing the Third
Circuit's decision. EPA is now proposing this FIP to address these
deficiencies, in accordance with the Court's directive, should it be
necessary to finalize a FIP to fulfill the Court's order.\10\
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    \10\ EPA plans to finalize the September 15, 2021, proposed
disapproval in the event we need to finalize this proposed FIP to
meet the court-ordered deadline. The court-ordered deadline preempts
the FIP timeline established by CAA section 110(c)(1) for a
finalized disapproval. See 86 FR 51317. EPA may promulgate a FIP
contemporaneously with or immediately following predicate final
action on a SIP (or finding no SIP was submitted). In order to
accomplish this, the EPA must necessarily be able to propose a FIP
prior to taking final action to disapprove a SIP or make a finding
of failure to submit. The Supreme Court recognized this in EME Homer
City by stating ``EPA is not obliged to wait two years or postpone
its action even a single day: The Act empowers the Agency to
promulgate a FIP `at any time' within the two-year limit.'' EPA v.
EME Homer City Generation, L.P., 572 U.S. 489, 509 (2014) (citations
omitted).
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D. Pennsylvania's Efforts To Respond to the Court's Decision

    PADEP undertook significant efforts to develop a SIP revision
addressing the deficiencies identified by the Third Circuit in the
Sierra Club decision. PADEP proceeded to develop source specific
(``case-by-case'') RACT determinations for the Cheswick, Conemaugh,
Homer City, Keystone, and Montour generating stations. As mentioned
above, the Bruce Mansfield facility ceased operation, so there is no
longer a need to address that facility. By April 1, 2021, each of the
five facilities had submitted permit applications to PADEP with
alternative RACT proposals in accordance with 25 Pa. Code 129.99. There
are a total of ten affected EGUs/units at the five facilities: Three at
Homer City, two each at Conemaugh, Keystone and Montour, and one at
Cheswick. Subsequently, PADEP issued technical deficiency notices to
obtain more information needed to support the facilities' proposed RACT
determinations. Although additional information was provided in
response to these notices, PADEP determined the proposals to be
insufficient and began developing its own RACT determination for each
facility. The outcome of this process was PADEP's issuance of draft
permits for each facility, which were developed with the intention of
submitting each case-by-case RACT permit to be incorporated as a
federally enforceable revision to the Pennsylvania SIP. Each draft
permit underwent a 30-day public comment period,\11\ during

which EPA provided source-specific comments to PADEP for each permit.
The draft permits, technical support memos for each permit drafted by
PADEP, and EPA's comments on each draft permit are included in the
docket for this proposed action. At this time, it is not known when, or
if, PADEP will submit these permits to EPA as SIP revisions to address
the Court's decision.
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    \11\ See 51 Pa.B. 5834, September 11, 2021 (Keystone); 51 Pa.B.
6259, October 2, 2021 (Conemaugh); 51 Pa.B. 6558, October 16, 2021
(Homer City); 51 Pa.B. 6930, November 6, 2021 (Montour); Allegheny
County Health Department Public Notices, December 2, 2021
(Cheswick).
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III. EPA's RACT Analysis and Proposed Emission Limits

    RACT is not defined in the CAA. However, as discussed above, EPA's
longstanding definition of RACT is ``the lowest emission limit that a
particular source is capable of meeting by the application of control
technology that is reasonably available considering technological and
economic feasibility.'' \12\ Pennsylvania has adopted a very similar
definition of RACT as ``[t]he lowest emission limit for VOCs or
NOX that a particular source is capable of meeting by the
application of control technology that is reasonably available
considering technological and economic feasibility.'' 25 Pa. Code
121.1. The Third Circuit decision ``assume[d] without deciding'' that
EPA's definition of RACT is correct. Sierra Club at 294. EPA is using
its longstanding definition of RACT to determine the limits proposed in
this FIP.
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    \12\ See Strelow Memo at 2.
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    The collection of sources addressed by the RACT analysis in this
proposed FIP has been determined by the scope of the Third Circuit's
order in the Sierra Club case and EPA's subsequent proposed disapproval
action.\13\ Herein, EPA is proposing RACT control requirements for the
five remaining facilities that were subject to the SIP provision which
the Court vacated EPA's approval of and which EPA thereafter proposed
to disapprove: Cheswick, Conemaugh, Homer City, Keystone, and Montour.
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    \13\ See 86 FR 51315 (September 15, 2021).
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    EPA is proposing that the RACT limits in this FIP will apply
throughout the year. For reasons explained in the next section, the
proposed limits are technologically and economically feasible during
the entire year. While other regulatory controls for ozone, such as the
Cross State Air Pollution Rule (CSAPR) and its updates, may apply
during a defined ozone season,\14\ the proposed RACT limits do not
authorize seasonal exemptions based on atmospheric conditions or other
factors since the RACT emissions rates are technologically and
economically feasible year-round. To the degree that the EPA analyses
underlying the RACT emissions limits proposed here rely on past
performance data, those calculations typically use ozone season data.
This is because ozone season data generally represent the time period
over which emissions rate performance of these units is the best. Put
another way, the ozone season data for the facilities examined here are
a reliable indicator of what is technologically and economically
feasible for these facilities, and EPA has no reason to believe that
achieving the same performance outside the ozone season would be
technologically or economically infeasible.
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    \14\ For example, the CSAPR and certain other regulations
addressing interstate transport of ozone and its precursors apply
during ``ozone season,'' which is defined for purposes of those
regulations as the period from May 1 to September 30 of each year.
See, e.g., 40 CFR 52.38(b)(1).
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A. Technologically Feasible NOX Controls for EGUs

    EPA has previously identified several technologically feasible
controls for reducing NOX from EGUs. NOX control
technologies are typically divided into combustion controls and post-
combustion controls. Combustion controls reduce the formation of
NOX during the combustion of fuel, and include low-
NOX burners (LNBs), over fire air (OFA), and natural gas
reburn (NGR). Post-combustion controls ``treat'' NOX
following its formation during combustion, and include Selective Non-
Catalytic Reduction (SNCR) and SCR. EPA's Alternative Control
Techniques Document for NOX Emissions from Utility Boilers
provides technical information for developing and implementing
regulatory programs to control NOX emission from fossil
fuel-fired boilers (EPA-453/R-94-023, 1994/03).\15\ The EPA Air
Pollution Control Cost Manual (Cost Manual) contains chapters with more
recent information, including that for cost, for these post-combustion
controls.\16\ The technical support document (TSD) for the Revised
CSAPR Update rule also explored several technologies for reducing
NOX emissions from EGUs, including SCR and SNCR, and
identified the likely cost of these controls.\17\
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    \15\ For the EPA Alternative Control Techniques Document for
NOX Emissions from Utility Boilers, see https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=2000INPN.txt.
    \16\ The Cost Manual can be found at https://www.epa.gov/economic-and-cost-analysis-air-pollution-regulations/cost-reports-and-guidance-air-pollution. Additionally, the relevant section of
the manual is included in the docket for this action. As of this
publication, there are no sections addressing combustion controls.
However, a section addressing low NOX and Ultra low
NOX burners is in development.
    \17\ For the TSD for the Revised CSAPR Update, see https://www.epa.gov/sites/default/files/2021-03/documents/egu_nox_mitigation_strategies_final_rule_tsd.pdf.
---------------------------------------------------------------------------

    All ten of the EGUs at the five facilities at issue have been
equipped with at least low NOX burners and overfire air
since the 1990s, and with SCRs beginning in the early 2000s, with the
exception of Conemaugh, which installed SCR in 2014. As such, low-
NOX burners, overfire air, and SCR are clearly
technologically feasible and proven technologies to reduce
NOX for the EGUs at these facilities. The specific
NOX and other pollutant controls on each EGU are discussed
in the TSD for this action (See section B--Facility Details). Having
determined that these technologies are technologically feasible, the
question shifts to identifying, through the application of some or all
of these technologies, what is the lowest NOX emission
limitation at these EGUs reasonably available considering technological
and economic feasibility.
    Section 4 (``NOX Controls''), Chapter 2 (``Selective
Catalytic Reduction'') of the Cost Manual contains a thorough
description of how SCRs work and the multiple factors affecting the
NOX removal efficiency (performance) of SCRs. The major
operational and design factors that affect the NOX removal
performance of SCRs include: Reaction temperature range; residence time
available in the optimum temperature range; degree of mixing between
the injected reagent and the combustion gases; molar ratio of injected
reagent to inlet NOX; inlet NOX concentration
level; and ammonia slip. Additional factors affecting NOX
removal efficiency of SCRs identified in the Cost Manual are: catalyst
activity; catalyst selectivity; pressure drop across the catalyst; ash
management (i.e., mitigating large particle ash (LPA) impacts on the
catalyst) and dust loading; catalyst pitch; sulfur dioxide
(SO2) and sulfur trioxide (SO3) concentrations in
gas stream; catalyst deactivation; and catalyst management.\18\
---------------------------------------------------------------------------

    \18\ See subsection 2.2.2 of section 4, Chapter 2 of the Cost
Manual.
---------------------------------------------------------------------------

    The temperature of the flue gas entering the SCR is a critical
factor affecting the performance of any SCR. The temperature of the
flue gas entering the SCR affects the degree (percentage) of
NOX reduction the SCR is capable of achieving, the
likelihood of creating unfavorable emissions from the SCR, such as
ammonia slip, and the potential for damage or fouling of the SCR

catalyst. As stated in the Cost Manual: ``The NOX reduction
reaction is effective only within a given temperature range. The use of
a catalyst in the SCR process lowers the temperature range required to
maximize the NOX reduction reaction. At temperatures below
the specified range, the reaction kinetics decrease, and ammonia passes
through the boiler (ammonia slip), but there is little effect on
nitrous oxide (N2O) formation. At temperatures above the
specified range, N2O formation increases and catalyst
sintering and deactivation occurs, but little ammonia slip occurs.''
\19\ The Cost Manual also notes that ``In an SCR system, the optimum
temperature depends on both the type of catalyst used in the process
and the flue gas composition. For the majority of commercial catalysts
(metal oxides), the operating temperatures for the SCR process range
from 480 to 800 [deg]F (250 to 430 [deg]C). . . . [T]he rate of
NOX removal increases with temperature up to a maximum
between 700 and 750 [deg]F (370 to 400 [deg]C). As the temperature
increases above 750 [deg]F (400 [deg]C), the reaction rate and
resulting NOX removal efficiency begin to decrease.'' \20\
---------------------------------------------------------------------------

    \19\ Id.
    \20\ Id.
---------------------------------------------------------------------------

    Based in part on this language in the Cost Manual, EPA approved a
600-degree flue gas temperature threshold at which a 0.12 lb/MMBtu
NOX rate applied in the Pennsylvania RACT II SIP. However,
the Third Circuit found that both EPA's and PADEP's record lacked a
reasonable explanation for why 600 degrees was specifically selected by
PADEP as the SCR inlet flue gas temperature below which the higher
NOX emission rate applied.\21\
---------------------------------------------------------------------------

    \21\ Sierra Club at 303-307.
---------------------------------------------------------------------------

    As part of the approach used to develop the proposed rates for this
action, EPA examined data related to the threshold at which these
facilities can effectively operate their SCR. Since the date of the
Third Circuit decision (August 27, 2020), EPA has obtained from PADEP a
few redacted pages of the SCR Operator's Manual for Conemaugh and
Keystone, as well as hourly flue gas temperature, reagent injection
amounts, and NOX emission data for the years 2017 through
2020 for those same facilities. These were submitted in response to
PADEP's technical deficiency letters and are included in the docket for
this action. Conemaugh's SCR manual lists 611 degrees Fahrenheit as the
minimum temperature for injecting reagent, while Keystone's manual says
612 degrees is the minimum continuous operating temperature for reagent
injection, but reagent can be injected for up to 3 hours at
temperatures between 582 and 611 degrees before the system
automatically shuts off reagent injection. Because these two facilities
provided only a few select pages of their SCR manuals, EPA cannot be
certain whether there are, or are not, other operating scenarios and/or
SCR inlet temperatures at which reagent could be injected. Furthermore,
it is unclear whether the operating manual reflects a specific analysis
of the injection protocol that would result in the greatest
NOX reductions, as RACT requires. However, in comments
submitted in response to the Ozone Transport Commission (OTC)'s CAA
section 184(c) petition,\22\ Conemaugh and Keystone also identified the
threshold in Megawatts (MW) at which they could operate their
respective SCRs (see Table 1).\23\
---------------------------------------------------------------------------

    \22\ CAA section 184(a) establishes a commission for the OTR,
the OTC, consisting of the Governor of each state or their
designees, the Administrator or their designee, the Regional
Administrators for the EPA regional offices affected (or the
Administrator's designees), and an air pollution control official
representing each state in the region, appointed by the Governor.
Section 184(c) specifies a procedure for the OTC to develop
recommendations for additional control measures to be applied within
all or a part of the OTR if the OTC determines that such measures
are necessary to bring any area in the OTR into attainment for ozone
by the applicable attainment deadlines. On June 8, 2020, the OTC
submitted a recommendation to EPA for additional control measures at
certain coal-fired EGUs in Pennsylvania. See 85 FR 41972; July 13,
2020.
    \23\ See p. 17 of the comments, in the docket for the section
184(c) petition, found at https://www.regulations.gov/comment/EPA-HQ-OAR-2020-0351-0022.
---------------------------------------------------------------------------

    PADEP also provided 30 days of similar data submitted by Montour,
which included the inlet temperature and reagent injection amounts.
Montour also provided an apparently complete copy of its SCR Operation
and Maintenance Manual to PADEP, but this manual was not included in
the information provided to EPA.
    Absent more complete temperature data and operating manuals for all
facilities, EPA then analyzed historical operating data submitted to
EPA by each of these facilities in order to determine the operating
threshold at which Cheswick, Montour, and Homer City could inject
reagent and run their SCRs to develop the same MW measure for these
three facilities as for Conemaugh and Keystone.\24\ For Homer City,
Montour, and Cheswick, EPA looked at hourly data for these sources in
EPA's Power Sector Emissions Data for ozone seasons 2002 through 2020,
except for any years when the source did not have SCR installed.\25\
(See explanation in the introduction to this section for why these
analyses use ozone season data) EPA created scatter plots showing
hourly NOX emission rates by gross hourly load (MW/hr) for
each unit's three best performing ozone seasons (in terms of overall
ozone season average rate), as well as data from its two most recent
ozone seasons (which was 2019 and 2020 at the time).\26\ From these
scatter plots, the SCR threshold was approximated through visual
inspection, i.e., by identifying each unit's approximate gross load,
above each unit's minimum operating load, at which NOX rates
below 0.2 lb/MMBtu were achieved in the years analyzed. The full
analysis and methodology are discussed in detail in the TSD. The
results of this analysis, as well as the reported values for Conemaugh
and Keystone, are shown in Table 1 in this preamble.
---------------------------------------------------------------------------

    \24\ Conemaugh and Keystone submitted data in response to the
OTC's CAA section 184(c) petition identifying the MW input at which
it typically operates or can operate the SCRs. EPA reviewed the
historic operating data for these facilities as it did for Homer
City, Montour, and Cheswick, and found that Keystone and Conemaugh's
stated thresholds were consistent with the data. EPA thus relied
upon the stated values for Keystone and Conemaugh in the development
of this action's proposed rates.
    \25\ https://www.epa.gov/airmarkets/power-sector-emissions-data.
    \26\ See Appendix 5 of the TSD for this action.

                    Table 1--Observed SCR Thresholds
------------------------------------------------------------------------
                                                           SCR threshold
                Facility name                     Unit         (MW)
------------------------------------------------------------------------
Conemaugh....................................          1             450
Conemaugh....................................          2             450
Keystone.....................................          1             660
Keystone.....................................          2             660
Homer City...................................          1             320
Homer City...................................          2             320
Homer City...................................          3             320
Montour......................................          1             380
Montour......................................          2             380
Cheswick.....................................          1             290
------------------------------------------------------------------------

    Given the role of gas temperature in SCR performance, EPA
considered how best to use this information in establishing RACT limits
that address the Third Circuit's concerns about allowing less stringent
limits when flue gas temperatures went below what it considered to be
an arbitrary temperature threshold. This is a challenging factor to
consider in cases when the operating temperature varies, and when the
units spend some time at temperatures where SCR is very effective, and
some time at temperatures where it is not. To assess whether the units
in this FIP exhibit this pattern, EPA evaluated years of data submitted
by these sources to EPA to characterize their variability in hours of
operation or

level of operation.\27\ In particular, EPA used this information to
identify whether, or to what degree, the EGUs have shifted from being
``baseload'' units (i.e., a steady-state heat input rate generally
within SCR optimal temperature range) to ``cycling'' units (i.e.,
variable heat input rates, possibly including periods below the SCR
optimal temperature range). All of these EGUs were designed and built
as baseload units, meaning the boilers were designed to be operated at
levels of heat input near their design capacity 24 hours per day, seven
days per week, for much of the year. As a result, the SCRs installed in
the early 2000s were designed and built to work in tandem with a
baseload boiler. In particular, the SCR catalyst and the reagent
injection controls were designed for the consistently higher flue gas
temperatures created by baseload boiler operation. In more recent
years, for multiple reasons, these old, coal-fired baseload units have
struggled to remain competitive when bidding into the PJM
Interconnection (PJM) electricity market.\28\ Nationally, total
electric generation has generally remained consistent, but between 2010
and 2020, generation at coal-fired utilities has declined by 68%.\29\
As a result, many of these units, on a daily basis, more recently have
tended to cycle between high heat inputs, when electricity demand is
high, and lower heat inputs or complete shutdowns, when demand is low.
This cycling behavior can affect the ability of the EGUs to operate
their SCRs because at lower heat inputs the temperature of the flue gas
can drop below the operating temperature for which the SCR was
designed.\30\ Accordingly, this proposal seeks to establish limits that
account for the technical limits on SCR operation that can result from
this cycling behavior.
---------------------------------------------------------------------------

    \27\ See the Excel spreadsheet entitled ``PA-MD-DE SCR unit data
2002-2020.xlsx'' in the docket for this action.
    \28\ PJM is a regional transmission organization (RTO) or grid
operator which provides wholesale electricity throughout 13 states
and the District of Columbia.
    \29\ U.S. Energy Information Administration, ``Electric Power
Annual 2020,'' Table 3.1.A. Net Generation by Energy Source, https://www.eia.gov/electricity/annual/.
    \30\ U.S. EPA, ``EPA Alternative Control Techniques Document for
NOX Emissions from Utility Boilers'' EPA-453/R-94-023,
March 1994, p. 5-119, https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=2000INPN.txt.
---------------------------------------------------------------------------

    As alluded to above, PADEP attempted to address this cycling
behavior by creating tiered emissions limits for different modes of
operation based on the flue gas temperature, which its RACT II rule
expressed as a transition from the 0.12 lb/MMBtu rate to much less
stringent rates (between 0.35 and 0.4 lb/MMBtu, depending on the type
of boiler) based on a temperature cutoff of 600 degrees, with the less
stringent rate essentially representing a ``no-SCR'' mode (i.e., an
emission limit applicable at times when the SCR has been idled or
bypassed and is not actively removing NOX). The Third
Circuit rejected this approach because the selection of the cutoff
temperature was not sufficiently supported by the record.\31\ The Third
Circuit decision also questioned the need for a the less stringent
rate, noting that nearby states do not have different emission rates
based on inlet temperatures.\32\
---------------------------------------------------------------------------

    \31\ See Sierra Club at 303-307.
    \32\ Id. at 303.
---------------------------------------------------------------------------

    EPA has considered the Court's concerns and has further considered
the practical and policy implications in structuring a tiered limit for
these cycling EGUs based on operating temperature. As such, EPA has
decided against proposing a tiered limit. The effectiveness of SCR does
not drop to zero at a single temperature point and defining the minimum
reasonable temperature range to begin reducing SCR operation for the
purposes of creating an enforceable RACT limit is a highly technical,
unit-specific determination that depends on several varying factors.
EPA expects that defining a specific mode where SCR cannot or should
not operate would be exceedingly complex and require information that
EPA does not have, showing, for each unit, complete information on all
the effects of varying temperature levels on SCR operation and
emissions control performance. Such a tiered limit would also require
extensive recordkeeping of the source's relevant operating parameters
that form the basis of the tiers in order to be enforceable, as the
Court noted in its ruling regarding the need to keep detailed
temperature records.
    EPA has an additional concern about addressing cycling operation
through a tiered RACT limit based on operating temperature. It is
reasonable to expect that, to the degree that the heat input of sources
during cycling mode is under source control, the creation of a tiered
limit that allows no-SCR operation at certain inlet temperatures would
create an incentive for the source to cycle to temperatures where SCR
is not required, in order to avoid SCR operating costs and potentially
gain a competitive advantage. In the case of the Pennsylvania limits
addressed by the Third Circuit's decision, there was no limit on how
much time the units could spend in no-SCR mode. In section C of the TSD
for this action, EPA shows that over the last decade, some affected
sources have varied the gross load level to which they cycle down,
hovering either just above or just below the threshold at which the SCR
can likely operate effectively.
    Depending on the unit, this slight change in electricity output
could significantly affect SCR operation and the resulting emissions
output. Though instances of cycling below SCR thresholds occurred in
some cases prior to the implementation of Pennsylvania's tiered RACT
limit and thus the limit may not be the sole driver of the behavior
following its implementation, the limit certainly allows this behavior
to occur. While EPA acknowledges the need for EGUs to operate at times
in modes where SCR cannot operate, EPA believes its RACT limit should
minimize incentives to do that, and a tiered rate structure that
effectively has no limit on no-SCR operation tends to do the opposite.
    On the other hand, EPA is also concerned about a RACT limit that
treats these EGUs as always operating as baseload units by imposing a
NOX emission rate that applies at all times but can
technically be achieved only if the boiler is operating at high loads.
Recent data indicates that these units are not operating as baseload
units and are not likely to do so in the future.\33\ Selecting the best
baseload rate (the rate reflecting SCR operation in the optimal
temperature range) and applying that rate at all times does not account
for, and could essentially prohibit, some cycling operation of these
units. Cycling has become more common at coal-fired EGUs because they
are increasingly outcompeted for baseload power. In the past, these
units were among the cheapest sources of electricity and would often
run close to maximum capacity. Over time, other EGUs can now generate
electricity at lower costs than the coal-fired units. Thus, the coal-
fired units now cycle to lower loads during hours with relatively low
system demand (often overnight and especially during the spring and
fall ``shoulder'' seasons when space heating and cooling demand is
minimized) when their power is more expensive than the marginal supply
to meet lower load levels. Hence, they cycle up and down as load, and
demand-driven power prices, rise and fall and they operate when the
price meets or exceeds their cost to supply power. EPA acknowledges
that cycling down to a

no-SCR mode may sometimes happen, for example, when electricity demand
drops unexpectedly, and other units provide the power at a lower cost.
The consideration of the technical and economic feasibility of a given
RACT limit should reflect, to the extent possible, consideration of the
past, current, and future expected operating environment of a given
unit. EPA seeks comment on how best to consider these feasibility
issues to establish a rate for each unit that would reflect a
reasonable level of load-following (cycling) (e.g., a level consistent
with similar SCR-equipped units) but that also accounts for the lower
historic NOX rates that these units have achieved.
---------------------------------------------------------------------------

    \33\ See section C of the TSD for this action.
---------------------------------------------------------------------------

B. Weighted Rates Approach and Analysis

    Given these concerns, EPA is proposing to express the RACT limits
for these units using a weighted rate limit. The weighted rate
incorporates both a lower ``SCR-on'' limit and a higher ``SCR-off''
limit. Through assignment of weights to these two limits based on the
proportion of operation in SCR-on and SCR-off modes during a period of
operation that represents a reasonably low amount of SCR-off operation,
the SCR-on and SCR-off limits are combined into a single RACT limit
that applies at all times. The weight given to the proposed SCR-off
limit (established as described later in this section) has the effect
of limiting the portion of time a cycling source can operate in SCR-off
mode and incentivizes a source to shift to SCR-on mode to preserve
headroom under the limit. While driving SCR operation, the weighted
limit accommodates the need for an EGU to occasionally cycle down to
loads below which SCR can operate effectively and does not prohibit no-
SCR operation or dictate specific times when it must occur. In this
way, the proposed approach avoids the difficulty of precisely
establishing the minimum temperature point at which the no-SCR mode is
triggered, effectively acknowledging the more gradual nature of the
transition between modes where SCR is or is not effective. Finally, it
is readily enforceable through existing Continuous Emission Monitoring
Systems (CEMS), without the need for development of recordkeeping for
additional parameters that define the SCR-off mode. The approach is
described in more detail below.
    As a starting point for developing the weighted rates for each
unit, EPA calculated both ``SCR-on'' and ``SCR-off'' rates using
historic ozone season operating data for the unit to determine when the
SCR was likely running and when it was likely not running, and then
established rates that represent the lowest emission limit that is
reasonably available considering economic and technological
feasibility. Using the EPA (or source) derived minimum SCR operation
threshold as described in section III.A in this preamble, expressed as
Megawatts (MW) in Table 1 in this preamble, EPA calculated average
``SCR-on'' and ``SCR-off'' rates for each unit based on historic
operating data for that unit, when available, from 2003 to 2021. For
detail on the development of these rates, see section D of the TSD for
this action. The ``SCR-on'' rate is an average of all hours in which
the SCR was likely running (operating above the threshold at which it
can run the SCR with an hourly NOX emission rate below 0.2
lb/MMBtu) during each unit's third best ozone season from the period
2003 to 2021. The third best ozone season was identified based on the
unit's overall average NOX emission rate during each ozone
season from 2003 to 2021. This 18-year time period captures all the
years of SCR operation for each facility, with the exception of
Conemaugh, which only installed SCR in 2014.\34\ EPA included all these
years of data because the Third Circuit's decision questioned EPA's
review of only certain years of emissions data for these sources in
determining whether to approve Pennsylvania's RACT II NOX
emission rate for these EGUs. The use of the 3rd-best year accounts for
degradation of control equipment over time. EPA used a third best ozone
season approach for the Revised CSAPR Update (86 FR 23054, April 30,
2021) and the proposed Good Neighbor Plan for 2015 Ozone NAAQS (87 FR
20036, April 6, 2022) (2015 Good Neighbor Plan). The ``SCR-off rate''
is an average of all hours in which the unit's SCR was likely not
running (operating below the threshold at which it can run the SCR with
an hourly NOX rate above 0.2 lb/MMBtu) during all ozone
seasons from 2003-2021. All ozone seasons in the time period were used
to increase the sample size of this subset of the data, as an
individual ozone season likely contains significantly fewer data points
of non-SCR operation.
---------------------------------------------------------------------------

    \34\ Because the facility installed SCR in late 2014, the only
ozone seasons available to analyze Conemaugh's operation with SCR
are 2015-2021. In addition, Conemaugh's average ozone season
NOX rates vary significantly over this time period. Given
the relative newness of Conemaugh's SCRs, and the fewer number of
years of data and the wide variation in rates in those years, EPA
decided that the second-best ozone season represents reasonable SCR
performance for Conemaugh.
---------------------------------------------------------------------------

    Using the thresholds listed in Table 1 in this preamble, EPA then
calculated the SCR-on and SCR-off ``weights,'' which represent the
amount of heat input spent above (SCR-on) or below (SCR-off) the SCR
threshold, for each EGU. For the weights, EPA evaluated data from the
2011 to 2021 ozone seasons and selected the year in which the EGU had
its third highest proportion of heat input spent above the SCR
threshold during this time period, using that year's weight (the
``third best weight'') together with the SCR-on/SCR-off rates described
previously to calculate the weighted rate. The years 2011-2021 were
analyzed because they likely are representative of the time period that
encompasses the years when the units began to exhibit a greater cycling
pattern, and it is reasonable to expect that this pattern will continue
for the foreseeable future.
    Using these data, EPA is proposing emissions limitations based on
the following equation:

(``SCR-on'' weight * ``SCR-on'' mean rate) + (``SCR off'' weight *
``SCR off'' mean rate) = emissions limit in lb/MMBtu.

    The calculation for each limit is based on the third best weight
for each unit over the 2011 to 2021 time period. Using the third best
weight will eliminate the weights that represent years with the most
frequent ``no-SCR'' cycling, especially the years in which cycling to
just below the SCR threshold became more prevalent, in order to act as
a limit on the potential for excessive no-SCR operation and incentivize
SCR use. At the same time, using the third best weight will also
minimize the weights that represent periods when minimal cycling was
occurring (i.e., baseload operation), in order to ensure that the limit
is not forcing cycling to be infeasibly constrained. The third best
weight is therefore consistent with the RACT requirement: It represents
the lowest rate reflecting SCR application, taking both reasonable
technological and economic feasibility into account.

C. Proposed NOX Emission Rate Limits

    Table 2 in this preamble presents the proposed NOX
Emission RACT rate limits for each facility that result from the
application of the weighted approach. Table 2 in this preamble also
presents the range of rates that would be generated using minimum
(i.e., more baseload) and maximum (i.e., more cycling) weights over the
period. EPA is taking comment on its proposed limits, and is also
soliciting comment on all the values in this range as potential
alternatives. More details about the weighted rates analysis can be
found in section D of the TSD for this action.

                                   Table 2--Proposed NOX Emission Rate Limits
----------------------------------------------------------------------------------------------------------------
                                                                                Proposed
                                           Low range rate    High range rate    Weighted rate   facility-wide 30-
        Facility name             Unit       (lb/MMBtu)        (lb/MMBtu)        (lb/MMBtu)     day average rate
                                                                                limit (lb/MMBtu)
----------------------------------------------------------------------------------------------------------------
Cheswick.....................          1             0.085             0.195             0.099             0.099
Conemaugh....................          1             0.071             0.132             0.091             0.091
Conemaugh....................          2             0.070             0.132             0.094
Homer City...................          1             0.102             0.190             0.102             0.088
Homer City...................          2             0.088             0.126             0.088
Homer City...................          3             0.096             0.136             0.097
Keystone.....................          1             0.046             0.170             0.076             0.074
Keystone.....................          2             0.045             0.172             0.074
Montour......................          1             0.047             0.131             0.069             0.069
Montour......................          2             0.048             0.145             0.070
----------------------------------------------------------------------------------------------------------------

    The resulting NOX emission rate limits will be based on
a 30-day rolling average, and will apply at all times, including during
operations when exhaust temperatures are too low for the SCR to
operate, or operate optimally. For facilities with more than one unit,
the proposed limit will allow facility-wide averaging for compliance,
but the average limit will be based on the weighted rate achieved by
the best performing unit. Using the best performing unit as the basis
for RACT is appropriate, as it would prioritize increased utilization
of the best performing units in SCR-on mode. EPA is proposing a 30-
operating day, rolling average for this rate-based (i.e., lb/MMBtu)
limit. EPA and many states have used such 30-day average limits for
this type of limit, where the measured daily lb/MMBtu rate can vary
significantly depending on the way the boilers and SCRs are operated in
a day, but the limit is designed to apply at all times. A 30-day
average ``smooths'' this variability by averaging the current value
with the prior values over a rolling 30-day period to determine
compliance. While some period of lb/MMBtu values over the target rate
can occur without triggering a violation, they must be offset by
corresponding periods where the lb/MMBtu rate is lower than the target
rate (i.e., the 30-day rolling average rate). Such averaging periods
have precedent not only in Federal rulemaking,\35\ but in EPA's
approval of SIPs.\36\ Such a limit can represent RACT so long as it is
based on 30-day periods that represent the lowest rate the source is
capable of meeting over such period through the application of control
technology that is reasonably available considering technological and
economic feasibility. When EPA previously provided presumptive RACT
limits for coal-fired EGUs, it expressed them as 30-day averages.\37\ A
30-day average is similarly appropriate here, as the proposed rate
limits here would apply at all times, throughout the year, to units
that are expected to exhibit cycling operation as described previously.
While there may be periods (typically when cycling down to where the
SCR cannot operate effectively) where the lb/MMBtu rate is exceeded,
these periods are limited in time by the weighted rate, and must be
offset by periods where the lb/MMBtu rate is correspondingly lower to
meet 30-day average limit.
---------------------------------------------------------------------------

    \35\ See Coal-fired EGU new source performance standards (NSPS);
40 CFR 60.44.
    \36\ EPA has approved 30-day rolling averages as ``short-term''
RACT limitations in SIP revisions submitted by New York and
Wisconsin. See 75 FR 64155 (October 19, 2010) for Wisconsin and 78
FR 41846 (July 12, 2013) for New York.
    \37\ See ``State Implementation Plans; Nitrogen Oxides
Supplement to the General Preamble for the Implementation of Title I
of the Clean Air Act Amendments of 1990'' at 57 FR 55625 (November
25, 1992).
---------------------------------------------------------------------------

D. Proposed Daily NOX Mass Emission Limits

    EPA is also proposing a unit-specific daily NOX mass
emission limit (i.e., lb/day) to complement the weighted facility-wide
30-day NOX emission rate limit and further ensure RACT is
applied continuously. High emissions days are a concern, given the 8-
hour averaging time of the underlying 1997 and 2008 ozone NAAQS. This
proposed daily NOX mass emission limit was calculated by
multiplying the proposed facility-wide 30-day rolling average
NOX emission limit (in lb/MMBtu) by each unit's heat input
maximum permitted rate capacity (in MMBtu/hr) by 24 hours. While the
30-day average rate limit ensures that SCR is operated where feasible
while reasonably accounting for cycling, EPA is concerned that units
meeting this limit might still occasionally have higher daily mass
emissions on one or more days where no or limited SCR operation occurs,
which could trigger exceedances of the ozone NAAQS if these high mass
emissions occur on days conducive to ozone formation, such as
especially hot summer days. Notably, the OTC also raised the issue of
daily emission limits in its CAA section 184(c) petition.
    For example, in PADEP's ``Technical Evaluation for Case-by-Case
RACT, Conemaugh Generating Station,'' the performance of Conemaugh Unit
1 during the month of April 2020 was evaluated. PADEP determined that
for most of the month, the unit ran at approximately 75% heat capacity,
yet no reagent was injected on most days. Daily NOX mass
emissions were predictably high. For example, on April 2, 2020, Unit 1
ran at roughly 75% heat capacity for about 20 out of the 24 hours. The
NOX emissions rate over that period was roughly 0.275 lb/
MMBtu.\38\ Twenty hours at 75% heat capacity at 0.275 lb/MMBtu results
in approximately 34,000 lbs of NOX emitted. In contrast,
twenty hours at 75% heat capacity at the proposed 0.091 lb/MMBtu
weighted rate would result in much less NOX being emitted:
Approximately 11,260 lbs. The addition of a unit-specific daily mass
emission limit at an appropriate level will address concerns that a
facility-wide 30-day average emission rate, by itself, may not curtail
certain days where higher emission rates result in higher mass
emissions of NOX. These foregone emissions reductions could
have serious NAAQS implications on days where high ozone levels are
likely to occur. A properly operating SCR can reduce NOX
emissions by between 50% to 90%. For example, looking at the same
Conemaugh Unit 1 data on a different day, September 30, 2017, the unit
operated around 50% load for the entire

day, but the facility apparently elected to operate the SCR since the
NOX emission rate for that day was 0.05 lb/MMBtu, which is
82% lower than the April 2, 2020, NOX rate.
---------------------------------------------------------------------------

    \38\ See ``Technical Evaluation for Case-by-Case RACT, Conemaugh
Generating Station'' at 7.
---------------------------------------------------------------------------

    For these reasons, EPA believes it is reasonable to propose an
additional unit-specific lb/day mass limit as an additional safeguard.
The proposed daily mass limit would be an additional constraint on no-
SCR operation within a single day. It provides for some boiler
operation without using the SCR, which may be unavoidable during part
of any given day, but it constrains such operation because the mass
limit will necessitate SCR operation (for example by raising heat input
to a level where the SCR can operate) if the unit is to continue to
operate while remaining below this limit. This provides greater
consistency with the RACT definition. Table 3 in this preamble shows
the proposed unit-specific NOX mass limits, which are to be
met on a 24-hr basis.

                    Table 3--Proposed NOX Mass Limits
------------------------------------------------------------------------
                                           Permitted max
                                            hourly heat   Proposed unit-
        Facility name             Unit      input rate     specific mass
                                            (MMBtu/hr)    limit (lb/day)
                                               \39\
------------------------------------------------------------------------
Cheswick.....................          1           6,000          14,256
Conemaugh....................          1           8,280          18,084
Conemaugh....................          2           8,280          18,084
Homer City...................          1           6,792          14,345
Homer City...................          2           6,792          14,345
Homer City...................          3           7,260          15,333
Keystone.....................          1           8,717          15,481
Keystone.....................          2           8,717          15,481
Montour......................          1           7,317          12,117
Montour......................          2           7,239          11,988
------------------------------------------------------------------------

    Table 4 in this preamble shows the reductions these proposed limits
would realize when compared to 2021 emissions data.
---------------------------------------------------------------------------

    \39\ Title V Permit maximum heat input rates.

                     Table 4--2021 Annual NOX Emissions and Rates Compared to Proposed Rates
----------------------------------------------------------------------------------------------------------------
                                                                                Potential
                                   2021 average    Proposed 30-    Proposed rate     2021 NOX      change in NOX
            Facility               NOX rate (lb/   day NOX rate      vs. 2021        emissions    mass emissions
                                      MMBtu)        (lb/MMBtu)      average (%)       (tons)          (tons)

----------------------------------------------------------------------------------------------------------------
Cheswick........................           0.139           0.099             -29           1,069            -309
Conemaugh.......................           0.149           0.091             -39           5,506          -2,132
Homer City......................           0.133           0.088             -34           3,144          -1,060
Keystone........................           0.142           0.074             -48           5,481          -2,618
Montour.........................           0.110           0.069             -37             649            -241
    Net.........................  ..............  ..............  ..............          15,850        * -6,361
----------------------------------------------------------------------------------------------------------------
* -40%

E. Technological and Economic Feasibility of EPA's Proposed RACT Limits

    EPA is proposing to determine that the limits discussed in the
prior section are technologically feasible, in part because the limits
have been met by each of the facilities affected by the proposed FIP.
During the process of reviewing PADEP's proposed source specific
permits, EPA evaluated past performance of the units in question, as
shown in Appendix 1 of the TSD for this action. EPA looked at data from
the best and third-best ozone seasons (second best for Conemaugh) over
its entire record of operation with SCR, as well as data from just
recent ozone seasons (2010-2020), with 2019 shown individually. For
each of those time periods, EPA calculated the best daily average, the
mean daily average, and the 99th percentile of daily average
NOX emissions.
    As previously discussed, RACT is not the lowest rate achievable by
a particular source (or source category). Nor, as the Third Circuit
pointed out, are RACT requirements satisfied by a limit that represents
``. . . an average of the current emissions being generated by existing
systems.'' Sierra Club at 14-15. Rather, as previously discussed, RACT
is the lowest emission limit that a particular source is capable of
meeting by the application of the control technology that is reasonably
available considering technological and economic feasibility. By
considering historical data that represent the best performing years,
as well as more recent years where the changing realities of electrical
generation have presented legitimate technological challenges to
meeting those best rates, EPA's weighted rate approach is reasonable,
and consistent with the CAA's RACT requirements. It represents a
considerable improvement over the status quo, and still allows these
sources the flexibility to address fluctuating power demands from the
grid operator, so long as operation without SCR is reasonably
constrained.
    Economic feasibility in the context of RACT is not a ``bright-
line'' or ``one-size-fits-all'' test with a clearly established
threshold between what is and what is not economically feasible.
Rather, it involves a case-by-case evaluation, and ``. . . is largely
determined by evidence that other sources in a source category have in
fact

applied the control technology in question.'' \40\ In the case of these
five facilities, because the controls are already installed (no costs
to install or retrofit control equipment), the economic analysis
partially involves comparing the emissions limitations achieved by
similar sources which operate under similar electrical dispatch
constraints, as well as considering the extent to which all of these
units have in fact demonstrated an ability to meet the proposed limits
in the past. As discussed in more detail below, EPA's cost analysis was
consistent with the national, fleetwide approach applied in the context
of the CSAPR rulemakings, and the 2015 Good Neighbor Plan.
Additionally, EPA has made clear that economic feasibility should not
be conflated with affordability: ``Economic feasibility rests very
little on the ability of a particular source to `afford' to reduce
emissions to the level of similar sources. Less efficient sources would
be rewarded by having to bear lower emission reduction costs if
affordability were given high consideration.'' \41\
---------------------------------------------------------------------------

    \40\ See ``State Implementation Plans; General Preamble for the
Implementation of Title I of the Clean Air Act Amendments of 1990;
Supplemental;'' April 28, 1992; 57 FR 18074. See also 44 FR 53761
(September 17, 1979) (supplement to the general preamble on RACT)
and EPA Memorandum titled ``Criteria for Determining RACT in Region
IV'' dated June 19, 1985 (https://www.epa.gov/sites/default/files/2016-08/documents/criteria_for_determining_ract_in_region_iv_6-19-85.pdf).
    \41\ Id.
---------------------------------------------------------------------------

    Furthermore, EPA reviewed operating and emissions data of EGUs in
neighboring states which are also contractually obligated to the PJM
Interconnection and found that there was nothing unique about the
operating patterns of the units in Pennsylvania. EPA performed an
analysis comparing certain data for each of the Pennsylvania SCR-
equipped EGUs to data for the remaining SCR-equipped coal-fired EGUs in
Maryland (Brandon Shores 1,2, Morgantown 1,2, and Wagner 3) and
Delaware (Indian River 4). The data were compiled into a spreadsheet
which is included in the docket for this action.\42\ The data cover the
period from 2000 through 2020. The spreadsheet looks at the extent to
which changes in units' average ozone season NOX emission
rates over time can be explained by changes in their ozone season
operating patterns--i.e., operating fewer hours and spending a larger
fraction of the remaining operating hours at lower load levels.
---------------------------------------------------------------------------

    \42\ See ``PA-MD-DE SCR unit data 2000-2020.xlsx''
---------------------------------------------------------------------------

    EPA identified a multi-year baseline period after installation of
each analyzed unit's SCR when operation of the unit seemed fairly
stable and the NOX emission rate showed fairly consistent
SCR optimization. These periods vary by unit and range from 2 years to
9 years across parts of the 2001-2013 time period. For each unit, EPA
then compared the averages of the unit's seasonal average
NOX emission rate, seasonal total operating hours, and
seasonal average load level per operating hour during the baseline
period to the same unit's averages across the 2017-2019 period. EPA did
not identify a baseline period or perform the same specific comparisons
for Conemaugh units 1 and 2 because these units' SCRs were not
installed until 2015. The comparisons support several observations:
     Except for Keystone 1-2, all the units in all three states
have experienced moderate to very large decreases in seasonal total
operating hours--from 19% to 74%. By comparison, Keystone 1 and 2's
operating hours decreased only 3% and 7%. (Conemaugh's pattern of
changes in operating hours is similar to Keystone's).
     Except for Keystone 1 and 2 and Conemaugh 1 and 2, all the
units in Pennsylvania and Maryland have also experienced moderate to
large decreases in seasonal average load levels per operating hour--
from 20% to 37%. By comparison, Keystone 1 and 2's average load levels
per operating hour decreased only 6% and 9%. (Conemaugh's pattern of
changes is similar to Keystone's, and Indian River 4 had a 10%
decrease).
     Except for Homer City 3 (and Conemaugh 1 and 2), all the
Pennsylvania units experienced large increases in seasonal average
NOX emission rates from the baseline period to the 2017-2019
period--from 59% to 130%. Comparison to the Maryland units calls into
question whether these emission rate increases can reasonably be
attributed to changes in either the units' total operating hours or the
units' average load levels per operating hour, because the Maryland
units--which had changes in both of these variables much larger than
Keystone 1 and 2 and comparable to the other Pennsylvania units--all
experienced decreases in average emission rates from -6% to -25%
(Indian River 4 experienced an emission rate increase of 21%, but
stayed below 0.085 lb/MMBtu, and Homer City 3 experienced an emission
rate decrease of -2%.).
    In summary, the comparisons show that all five Maryland units (and
to a lesser extent the one Delaware unit) have experienced comparable
or greater changes in total operating hours and average load levels per
operating hour over time than the Pennsylvania units without a
deterioration in NOX emission rates comparable to the
deterioration shown by most of the Pennsylvania units.\43\
---------------------------------------------------------------------------

    \43\ EPA also notes that the cost of NOX allowances
under the various trading programs varied widely. See ``Allowance
Price Data All.xlsx'' in the docket for this action.
---------------------------------------------------------------------------

F. Increased Injection of Reagent and Increased Use of SCRs

    Fixed operation and maintenance (FOM) costs, such as operator
salaries, are independent of the operation of the control system and
are incurred by the operator regardless of variations in control
utilization. Variable operation and maintenance (VOM) costs are
proportional to the quantity of waste gas processed by the control
system. Because the SCRs at each EGU have already been installed and
have been operated for years (albeit in a less than optimal fashion),
FOM costs for the SCRs have already been incurred. Therefore, the
economic feasibility analysis for this proposal need only consider the
VOM costs associated with increased use of the SCRs. The most
significant of these costs is the cost of the additional reagent needed
to meet the proposed NOX limits and the additional cost of
more frequent catalyst replacement and maintenance that might occur
from greater use of the SCRs (compared to the status quo) to meet the
lower proposed NOX limit. EPA has recently evaluated VOM
costs associated with increased use of SCRs in a number of national
rulemaking actions related to the CAA's interstate transport
requirements, including most recently the proposed 2015 Good Neighbor
Plan. In the ``EGU NOX Mitigation Strategies Proposed Rule
TSD'' (2015 Good Neighbor Plan TSD) for the proposed rulemaking
(included in the docket for this action), EPA used the capital
expenses, and operation and maintenance costs for installing and fully
operating emission controls based on the cost equations used within the
Integrated Planning Model (IPM) that were researched by Sargent &
Lundy, a nationally recognized architect/engineering firm with EGU
sector expertise. From this research, EPA created a publicly available
Excel-based tool called the Retrofit Cost Analyzer (Update 1-26-2022)
(Retrofit Cost Analyzer) that implements these cost equations.\44\
---------------------------------------------------------------------------

    \44\ See https://www.epa.gov/airmarkets/retrofit-cost-analyzer
for the ``Retrofit Cost Analyzer (Update 1-26-2022)'' Excel tool.
---------------------------------------------------------------------------

    In the TSD for the 2015 Good Neighbor Plan, EPA used the Retrofit

Cost Analyzer to estimate the cost of additional reagent, as well as
additional VOM costs, including catalyst replacement and disposal.
Based on those calculations EPA estimated a representative marginal
cost of optimizing SCR controls to be approximately $1,600 per ton,
consistent with its estimation in the Revised CSAPR Update for this
technology. Additionally, depending on a unit's control operating
status, the representative cost at the 90th percentile unit (among the
relevant fleet of coal units with SCR covered in this rulemaking)
ranges between $900 and $1,700 per ton. EPA evaluated all coal-fired
units with SCR and determined that for those units with SCRs that are
already partially operating, the cost of optimizing is often much lower
than $1,600 per ton and is often under $900 per ton. (87 FR 20077;
April 6, 2022).
    EPA notes that while there is not a direct, one-to-one correlation,
the cost of reagents is impacted directly by fluctuations in
agricultural fertilizer markets. Fertilizer costs have risen
considerably since this analysis was performed. In March of 2022, the
cost of anhydrous ammonia was listed at roughly $1500/ton, and urea at
roughly $900/ton.\45\ The analysis performed for the 2015 Good Neighbor
Plan to arrive at a reagent cost of $500/ton involved calculations
using the cost of urea.\46\ However, all of the sources covered by this
proposed FIP currently use ammonia for reagent injection.
---------------------------------------------------------------------------

    \45\ See Appendix 3 of the TSD for this proposed FIP.
    \46\ See 2015 Good Neighbor Plan TSD at 5.
---------------------------------------------------------------------------

    Using the proposed NOX limits and associated predicted
NOX reductions in Table 4 in this preamble, and the
assumption from the 2015 Good Neighbor Plan TSD \47\ that the chemical
reaction requires 0.57 tons of ammonia for each ton of NOX
reduced, we calculated an updated $/ton of NOX removed using
current (March 2022) \48\ ammonia costs for the five facilities:
---------------------------------------------------------------------------

    \47\ See Id. at 4.
    \48\ See Appendix 3.

                        Table 5--Cost per NOX ($/ton) Removed Based on Additional Reagent
----------------------------------------------------------------------------------------------------------------
                                                                                Cost per ton
                                                     Predicted      Additional     Total annual   of NOX removed
                                                     reduction     reagent (tons     cost for     for additional
                    Facility                       (tons NOX per   per year from    additional      reagent ($/
                                                  year from 2021  2021 baseline)      reagent        ton) \+\
                                                     baseline)           *          [supcaret]
----------------------------------------------------------------------------------------------------------------
Cheswick........................................             309             176        $264,000            $854
Conemaugh.......................................           2,132           1,215       1,822,500             855
Homer City......................................           1,060             604         906,000             855
Keystone........................................           2,618           1,492       2,238,000             855
Montour.........................................             241             137         205,000             853
                                                 ---------------------------------------------------------------
    Average cost/ton............................  ..............  ..............  ..............             854
----------------------------------------------------------------------------------------------------------------
* Additional reagent = predicted reduction (tons) x 0.57 tons reagent/ton NOX reduction.
[supcaret] Total cost = additional reagent x $1500/ton reagent.
\+\ Cost per ton = total cost/predicted reduction.

    As previously noted, EPA's general evaluation of the costs of
optimizing an existing and already operating SCR in the 2015 Good
Neighbor Plan TSD was estimated to be from $900/ton to $1600 per ton of
NOX removed in 2016 dollars. This includes reagent costs, as
well as other VOM costs. EPA calculated the reagent-only portion of
those costs to be $500 per ton of NOX removed. Therefore,
the remaining, non-reagent VOM costs were determined to be $400-$1100
per ton. While other VOM costs may also have risen since this analysis
was conducted, it is unlikely that they have been as volatile as
soaring reagent costs, and EPA currently does not have reliable,
updated information beyond what was presented in the 2015 Good Neighbor
Plan on how VOM costs may have risen. Nevertheless, EPA believes that
it is unnecessary to re-evaluate the non-reagent VOM costs for the
purposes of this bounding analysis, aside from converting the figures
to 2022 dollars, because EPA predicts that the effects of any change in
non-reagent VOM would be minimal on the ultimate conclusion. Converting
the higher non-reagent VOM cost of $1100/ton NOX removed to
2022 dollars provides a revised non-reagent VOM cost of $1300/ton of
NOX removed. Combining this updated non-reagent cost and the
average reagent cost of $854/ton NOX removed based on
updated reagent prices (see Table 5 in this document), EPA estimates
that the cost of optimizing the existing SCRs in use at each facility
covered by this proposed FIP is approximately $2154/ton of
NOX removed. EPA finds this cost to be reasonable by any
metric, and determine, therefore, that the proposed limits are
economically feasible.\49\
---------------------------------------------------------------------------

    \49\ In 1985, EPA explained in a memo regarding cost
effectiveness for RACT that while it would be inappropriate to set a
specific threshold for economic feasibility, because RACT is
necessarily a case-by-case determination, ``[t]here are sources and
source categories for which costs in excess of $2,000/ton have been
determined to be reasonable.'' EPA Memorandum titled ``Criteria for
Determining RACT in Region IV'' dated June 19, 1985 (https://www.epa.gov/sites/default/files/2016-08/documents/criteria_for_determining_ract_in_region_iv_6-19-85.pdf).
---------------------------------------------------------------------------

    Additionally, while the $1600/ton of NOX removed cost
estimate used in the 2015 Good Neighbor Plan was presented on a
fleetwide basis, the Retrofit Cost Analyzer estimated individual costs
for Homer City Units 1-3, Keystone Units 1 and 2, Conemaugh Unit 1, and
Montour, using $350/ton for a 50% solution of urea. Those costs (in
2021 dollars) ranged from a low of $980/ton of NOX removed
for Homer City 3, to a high of $1152/ton of NOX removed for
Conemaugh.\50\ To assess the impact of the present, historic high
reagent costs, EPA re-ran the Retrofit Cost Analyzer with a reagent
cost of $1500/ton (of ammonia).\51\ EPA notes that we did not modify
other parameters in the Retrofit Cost Analyzer to directly convert urea
use to ammonia use. Rather, we took the conservative approach of using
the highest fertilizer cost in a bounding analysis to evaluate whether
past estimates of the cost effectiveness of increased reagent injection
were still

reasonable. The resulting $/ton of NOX removed estimates
ranged from $2590/ton of NOX removed for Homer City 3, to
$2757/ton of NOX removed for Conemaugh.\52\ Given the
likelihood of reagent costs returning to lower, historical levels, and
the fact that the remaining costs in the analyses were selected at the
90th percentile, EPA believes this bounding analysis to be reasonable
and conservative, and that these cost estimates, though higher than the
fleetwide averages discussed above, continue to be economically
feasible.
---------------------------------------------------------------------------

    \50\ See
``NOX_Control_Retrofit_Cost_Tool_Fleetwide_Assessment_Prop
osed_CSAPR_2015_NAAQS'' in the docket.
    \51\ This is a high end assumption not necessarily
representative of future markets, but used for the purposes of this
sensitivity. Combining current market conditions with the RCA
methodology would result in approximately $600 to $900 ton cost for
the urea cost for the future.
    \52\ See
``NOX_Control_Retrofit_Cost_Tool_Fleetwide_Assessment_Prop
osed_CSAPR_2015_NAAQS_PA'' in the docket.
---------------------------------------------------------------------------

G. Other Considerations

    EPA notes that in each of the draft permits submitted by PADEP, a
number of additional control technologies were evaluated by PADEP in
addition to SCR, but were determined to be either technologically or
economically infeasible. For example, in all cases except Montour,
PADEP determined that upgraded low NOX burners were
economically infeasible.\53\ PADEP determined that the costs per ton of
NOX removed ranged from $4,077 for Unit 1 at Conemaugh, to
$15,129 for Unit 3 at Homer City. EPA is not evaluating PADEP's
determinations related to economic feasibility in this action. However,
we did review this information for purposes of developing the proposed
FIP, and note that PADEP's source-specific analyses for ultra-low
NOX burners are higher than the fleet wide estimate of
$1600/ton of NOX removed by optimizing SCR use that EPA
derived in the 2015 Good Neighbor Plan.\54\ Furthermore, neither the
facilities nor PADEP considered the potential substantial impact that
state of the art combustion controls can have on reducing operating
costs of SCRs, including extended catalyst life and reducing reagent
consumption: ``Installation of front-end low-NOX combustion
systems or upgrades can essentially reduce total ammonia consumption by
as much as 45% and is a viable, cost-effective option to lowering plant
cost over the long term.'' \55\
---------------------------------------------------------------------------

    \53\ In the case of Montour, PADEP determined that no upgrade
was available, since Montour already has the best available
installed.
    \54\ See 2015 Good Neighbor Plan TSD at 16.
    \55\ See ``Technical Publication: State of the Art Low
NOX Burners to Reduce SCR Operating Costs;'' Babcock
Power; available at https://www.babcockpower.com/wp-content/uploads/2018/02/state-of-the-art-low-nox-burners-to-reduce-scr-operating-costs.pdf.
---------------------------------------------------------------------------

    Additionally, PADEP also evaluated a number of post combustion
technologies in their draft permits for these five facilities. These
post-combustion technologies increase the temperature of the flue gas
entering the SCR. Such technologies could, in the context of a weighted
limit approach, help lower the SCR-off weight by allowing a greater
range of SCR-on operating conditions. These include economizer bypass,
``V-Temp,'' and flue gas reheat. Economizer bypass is installed at
Homer City, and the V-Temp system, which similarly reduces heat
consumption in the economizer and thus increases inlet temperatures at
the SCR, is installed at Conemaugh, but was not used in 2019. PADEP
determined that continued operation of V-Temp at Conemaugh was not
technically feasible due to cycling operations. In the other cases,
PADEP determined installation to be technologically infeasible. Flue
gas reheat was not fully analyzed for technological and economic
feasibility at any of the sources. Additionally, no analysis was
presented to determine whether simply running at moderately higher
loads could be an economically feasible method to achieve lower
emissions rates. Finally, PADEP also determined in each case that it
appeared that the boilers had not been tuned in a manner that would
maximize NOX reductions. As part of this proposal, EPA did
not evaluate these technologies in the context of our RACT analysis. As
stated previously, EPA is proposing that the optimization of the
already installed equipment (the SCR) at each of these sources
represents RACT. EPA is proposing rates that greatly reduce the 30-day
NOX emissions in relation to past performance. Our
presumption is that the facilities have the flexibility to change their
operations to emit less NOX per unit of heat input, and we
identify these technologies as additional ways for the facilities to do
so, rather than requiring them as RACT. Moreover, we note that multiple
control schemes cannot always be implemented simultaneously and do not
always necessarily result in cumulative reductions.

IV. Recordkeeping and Reporting for Compliance Assurance

    EPA has included proposed recordkeeping and reporting requirements
in the regulatory language for this proposed FIP. The purpose of the
requirements is to ensure that each of the facilities subject to the
FIP can demonstrate compliance with their respective RACT limits as
finalized. EPA is proposing to require that each facility submit a
report to EPA every six months containing, among other things, the
following: Unit-specific daily operating time (hours); unit-specific
daily NOX mass emissions (lbs); unit-specific daily heat
input (MMBtu); unit-specific daily NOX emission rate (lb/
MMBtu); facility-wide 30-day rolling average NOX emission
rate (lb/MMBtu). The proposed regulatory language also defines certain
terms and specifies the method for calculating the facility-wide 30-day
rolling average NOX emission rate. These reports are to be
submitted to EPA within 30 days after the end of each six month
reporting period. In addition, the proposed regulatory language
requires the submission of a report containing certain information to
EPA within 10 business days if the source violates its 30-day rolling
average NOX limit or daily mass limit three or more times
within any 30-day period. The EPA is soliciting comment on whether the
six-month reporting period should be shorter (quarterly) and also on
other possible ways to improve the proposed recordkeeping and reporting
requirements included in this FIP.

V. Economic Analysis

    Based on the information presented in section III in this preamble,
in 2021, NOX emissions would have been reduced 6,361 tons.
Using $1600/ton of NOX removed cost estimate as in the 2015
Good Neighbor Plan would result in annual aggregate cost of
approximately $10 million dollars for 2021. As discussed in section III
in this preamble, EPA believe that a specific analysis of individual
plants would result in a lower estimate.
    In order to estimate the benefits of this rulemaking, EPA used a
``benefit per ton'' (BPT) approach. EPA has applied this approach in
several previous Regulatory Impact Analyses (RIA) \56\ in which the
economic value of human health impacts is derived using previously
established source-receptor relationships from photochemical air
quality modeling.\57\ The rule will reduce emissions of NOX,
a pollutant that is a precursor to both fine particulate matter
(PM2.5) and ground-level Ozone; for this reason, we quantify
the benefits of reducing each pollutant. These BPT estimates provide
the total monetized human health benefits (the sum of

premature attributable deaths and premature morbidity for either
PM2.5 or Ozone) of reducing 1 ton of NOX from a
specified source. This analysis draws upon benefit per-ton values
quantified for the Electricity Generating Unit (EGU) sector in
Pennsylvania. The method used to derive these estimates is described in
the ``Technical Support Document on Estimating the Benefit per Ton of
Reducing Directly-Emitted PM2.5, PM2.5 precursors
and Ozone Precursors from 21 Sectors and its precursors from 21
sectors.'' \58\ One limitation of using the BPT approach is an
inability to provide estimates of the health benefits associated with
exposure to nitrogen dioxide, the ambient concentrations of which may
also change as a result of this rulemaking. Another limitation is that
the photochemical-modeled emissions of the industrial point source
sector-attributable PM2.5 concentrations used to derive the
BPT values may not match the change in air quality resulting from the
emissions controls imposed by this FIP. Finally, an additional
limitation of this analysis is that we expect in future years that the
annual benefits (and cost) estimates will fall because some of these
units plan to retire by 2028. Table 6 in this preamble presents the
estimated economic value ranges of this proposed action.
---------------------------------------------------------------------------

    \56\ U.S. EPA. Regulatory Impact Analysis for the Federal
Implementation Plans to Reduce Interstate Transport of Fine
Particulate Matter and Ozone in 27 States; Correction of SIP
Approvals for 22 States. June 2011; Regulatory Impact Analysis for
the Final Mercury and Air Toxics Standards, December 2011; and
Regulatory Impact Analysis for the Particulate Matter National
Ambient Air Quality Standards; December 2012.
    \57\ Fann N, Fulcher CM, Hubbell BJ. The influence of location,
source, and emission type in estimates of the human health benefits
of reducing a ton of air pollution. Air Qual Atmos Health.
2009;2(3):169-176. doi:10.1007/s11869-009-004-0.
    \58\ U.S. EPA. 2021. Technical Support Document (BPT TSD) on
Estimating the Benefit per Ton of Reducing Directly-Emitted
PM2.5, PM2.5 Precursors and Ozone Precursors
from 21 Sectors and its precursors from 21 sectors. Technical
Support Document. Available at: https://www.epa.gov/benmap/reduced-form-tools-calculating-pm25-benefits.

Table 6--Estimated Discounted Economic Value of Avoided PM2.5 and Ozone-
       Attributable Premature Deaths and Illnesses for the Federal
               Implementation Plan, if Finalized, in 2022
------------------------------------------------------------------------
                                                Estimated economic value
    Discount rate             Pollutant           range (in millions of
                                                       2020$) \A\
------------------------------------------------------------------------
3%..................  Ozone \B\...............  $48 and $350.
                      PM2.5...................  $41 and $42.
                                               -------------------------
                      Sum of Ozone and PM2.5    $89 and $390.
                       \C\.
7%..................  Ozone...................  $43 and $320.
                      PM2.5...................  $37 and $38.
                                               -------------------------
                      Sum of Ozone and PM2.5..  $80 and $360.
------------------------------------------------------------------------
\A\ Values rounded to two significant figures. Benefits quantified using
  a benefit per-ton estimate.
\B\ We estimated ozone benefits for changes in NOX for the ozone season
  and PM2.5 attributable benefits resulting from annual changes in NOX.
\C\ Lower value calculated by summing ozone mortality estimated using
  the pooled short-term ozone exposure risk estimate and the Turner et
  al. (2016) long-term PM2.5 exposure mortality risk estimate. Upper
  value calculated by summing the Turner et al. (2016) long-term ozone
  exposure risk estimate and the Di et al. (2017) long-term PM2.5
  exposure mortality risk estimate.

VI. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive orders
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

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

    This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.

B. Paperwork Reduction Act

    This proposed action does not impose an information collection
burden under the provisions of the Paperwork Reduction Act (PRA).\59\ A
``collection of information'' under the PRA means ``the obtaining,
causing to be obtained, soliciting, or requiring the disclosure to an
agency, third parties or the public of information by or for an agency
by means of identical questions posed to, or identical reporting,
recordkeeping, or disclosure requirements imposed on, ten or more
persons, whether such collection of information is mandatory,
voluntary, or required to obtain or retain a benefit.'' \60\ Because
this proposed rule includes RACT reporting requirements for five
facilities, the PRA does not apply.
---------------------------------------------------------------------------

    \59\ 44 U.S.C. 3501 et seq.
    \60\ 5 CFR 1320.3(c) (emphasis added).
---------------------------------------------------------------------------

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations and small governmental jurisdictions.
    For purposes of assessing the impacts of this proposed rule on
small entities, small entity is defined as: (1) A small business as
defined by the Small Business Administration's (SBA) regulations at 13
CFR 121.201; (2) a small governmental jurisdiction that is a government
of a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise which is independently owned and operated
and is not dominant in its field.
    After considering the economic impacts of this proposed rule on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities under the
RFA. This rulemaking does not impose any requirements or create impacts
on small entities as no small entities are subject to the requirements
of this proposed rule.

D. Unfunded Mandates Reform Act (UMRA)

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public
Law 104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on state, local and tribal
governments and the private sector. Under section 202 of UMRA, the EPA
generally must prepare a written statement, including a cost-benefit
analysis, for final rules with ``Federal mandates'' that may result in
expenditures to state, local, and tribal governments, in the aggregate,
or to the private sector, of $100 million or more (adjusted for
inflation) in any one year.
    The EPA has determined that this proposed rule does not contain a
Federal mandate that may result in any expenditures by state, local or
tribal governments, and as explained in this document, the cost to the
private sector of the requirements will not exceed the inflation-
adjusted UMRA threshold of $100 million \61\ in any one year. Further,
this proposed action will not significantly or uniquely affect small
governments.
---------------------------------------------------------------------------

    \61\ Adjusted to 2019 dollars, the UMRA threshold becomes $164
million.
---------------------------------------------------------------------------

E. Executive Order 13132: Federalism

    Executive Order 13132, Federalism,\62\ revokes and replaces
Executive Orders 12612 (Federalism) and 12875 (Enhancing the
Intergovernmental Partnership). Executive Order 13132 requires the EPA
to develop an accountable process to ensure ``meaningful and timely
input by State and local officials in the development of regulatory
policies that have federalism implications.'' \63\ ``Policies that have
federalism implications'' is defined in

the Executive order to include regulations that 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.'' \64\ Under
Executive Order 13132, the EPA may not issue a regulation ``that has
federalism implications, that imposes substantial direct compliance
costs, . . . and that is not required by statute, unless [the Federal
Government provides the] funds necessary to pay the direct [compliance]
costs incurred by the State and local governments,'' or the EPA
consults with state and local officials early in the process of
developing the final regulation.\65\ The EPA also may not issue a
regulation that has federalism implications and that preempts state law
unless the agency consults with state and local officials early in the
process of developing the final regulation.
---------------------------------------------------------------------------

    \62\ 64 FR 43255, 43255-43257 (August 10, 1999).
    \63\ 64 FR 43255, 43257.
    \64\ Id.
    \65\ Id.
---------------------------------------------------------------------------

    This action does not have federalism implications. The proposed FIP
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, as specified in Executive Order 13132. Thus, Executive
Order 13132 does not apply to this action.

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

    Executive Order 13175, entitled ``Consultation and Coordination
with Indian Tribal Governments,'' requires the EPA to develop an
accountable process to ensure ``meaningful and timely input by tribal
officials in the development of regulatory policies that have tribal
implications.'' \66\ This proposed rule does not have tribal
implications, as specified in Executive Order 13175. It will not have
substantial direct effects on tribal governments. Thus, Executive Order
13175 does not apply to this rulemaking.
---------------------------------------------------------------------------

    \66\ 65 FR 67249, 67250 (November 9, 2000).
---------------------------------------------------------------------------

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

    The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive order. This action is not subject to
Executive Order 13045 because it implements a previously promulgated
health-based Federal standard. Further, the EPA believes that the
ozone-related benefits from this proposed rule will further improve
children's health.

H. Executive Order 13211: Actions Concerning Regulations 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

    Section 12 of the National Technology Transfer and Advancement Act
(NTTAA) of 1995 requires Federal agencies to evaluate existing
technical standards when developing a new regulation. Section 12(d) of
NTTAA, Public Law 104-113, 12(d) (15 U.S.C. 272 note) directs the EPA
to consider and use ``voluntary consensus standards'' in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures and business practices) that are developed or adopted by
voluntary consensus standards bodies. NTTAA directs the EPA to provide
Congress, through OMB, explanations when the agency decides not to use
available and applicable voluntary consensus standards.
    This proposed rulemaking does not involve technical standards.
Therefore, EPA is not considering the use of any voluntary consensus
standards.

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

    Executive Order 12898 establishes Federal executive policy on
environmental justice.\67\ Its main provision directs Federal agencies,
to the greatest extent practicable and permitted by law, to make
environmental justice part of their mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects of their programs, policies and
activities on minority populations and low-income populations in the
United States.
---------------------------------------------------------------------------

    \67\ Executive Order 12898 can be found 59 FR 7629 (February 16,
1994).
---------------------------------------------------------------------------

    The EPA believes that this action does not have disproportionately
high and adverse human health or environmental effects on minority
populations, low-income populations and/or indigenous peoples, as
specified in Executive Order 12898. EPA reviewed the Regulatory Impact
Analysis (RIA) prepared for the recently proposed 2015 Ozone NAAQS
transport FIP, and in particular the Ozone Exposure Analysis at section
7.4 of the RIA.\68\ Although that analysis projected reductions in
overall AS-MO3 ozone concentrations in each state for all affected
demographic groups resulting from newly proposed limits on EGUs and
non-EGUs (see Figure 7-3 of the RIA), it also found that emission
reductions from only EGUs would result in national reductions in AS-MO3
ozone concentrations for all demographic groups analyzed (see Figure 7-
2 of the RIA). In summation, that RIA concluded that the proposed FIP
is expected to lower ozone in many areas, including residual ozone
nonattainment areas, and thus mitigate some pre-existing health risks
of ozone across all populations evaluated (RIA, p. 7-32). Further, EPA
reviewed an analysis of vulnerable groups near the Conemaugh, Homer
City, and Keystone EGUs found in the TSD for EPA's proposed disapproval
of the S02 attainment plan for the Indiana, PA
S02 nonattainment area.\69\
---------------------------------------------------------------------------

    \68\ The RIA for that separate EPA action can be found at
www.regulations.gov under the docket number EPA-HQ-OAR-2021-0668.
Section 7.4 begins on page 7-9.
    \69\ See www.regulations.gov, Docket EPA-R03-OAR-2017-0615-0059,
pp. 14 -17.
---------------------------------------------------------------------------

    Based on EPA's review of those documents, and consideration of the
content of this proposed FIP including the proposed NOX
limits, EPA believes that this proposed FIP will serve to lower ozone
levels in many areas, including residual ozone nonattainment areas, and
thus mitigate some pre-existing health risks of ozone.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Continuous
emission monitoring, Electric power plants, Incorporation by reference,
Nitrogen oxides, Ozone, Reporting and recordkeeping requirements.

Michael Regan,
Administrator.

    For the reasons discussed in the preamble, 40 CFR part 52 is
proposed to be amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1.The authority citation for part 52 continues to read as follows:

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

Subpart NN--Pennsylvania

0
2. Section 52.2065 is added to read as follows:

Sec.  52.2065  Federal implementation plan addressing reasonably
available control technology requirements for certain sources.

    (a) Applicability. This section shall apply to Cheswick, Conemaugh,
Homer City, Keystone, and Montour, as defined in this section, as well
as any of their successors or assigns. Each of the five listed
facilities are individually subject to the requirements of this
section.
    (b) Effective date. The effective date of this section is June 24,
2022.
    (c) Compliance date. Compliance with the requirements in this
section shall commence immediately upon the effective date, except the
Facility-wide 30-Day Rolling Average NOX Emission Rate Limit
requirement in paragraph (f)(1) of this section will commence for the
Facility on the day that Facility has operated for thirty (30)
Operating Days after, and possibly including, the effective date.
    (d) General provisions. This section is not a permit. Compliance
with the terms of this section does not guarantee compliance with all
applicable Federal, state, or local laws or regulations. The emission
rates and mass emissions limits set forth in this section do not
relieve the Facility from any obligation to comply with other State and
Federal requirements under the Clean Air Act, including the Facility's
obligation to satisfy any State requirements set forth in the
applicable SIP.
    (e) Definitions. Every term expressly defined by this section shall
have the meaning given to that term in this section. Every other term
used in this section that is also a term used under the Act or in
Federal regulations in this chapter implementing the Act shall mean in
this section what such term means under the Act or the regulations in
this chapter.
    CEMS or Continuous Emission Monitoring System, means, for
obligations involving the monitoring of NOX emissions under
this section, the devices defined in 40 CFR 72.2 and installed and
maintained as required by 40 CFR part 75.
    Cheswick means, for purposes of this section, GenOn Power Midwest,
LP's Cheswick Generating Station consisting of one coal-fired unit
designated as Unit 1 (6,000 MMBtu/hr), located in Springdale, Allegheny
County, Pennsylvania.
    Clean Air Act or Act means the Federal Clean Air Act, 42 U.S.C.
7401-7671q, and its implementing regulations in this chapter.
    Conemaugh means, for purposes of this section, Keystone Conemaugh
Project LLC's Conemaugh Generating Station consisting of two coal-fired
units designated as Unit 1 (8,280 MMBtu/hr) and Unit 2 (8,280 MMBtu/
hr), located in West Wheatfield Township, Indiana County, Pennsylvania.
    Day or Daily means calendar day unless otherwise specified in this
section.
    EGU means electric generating unit.
    EPA means the United States Environmental Protection Agency.
    Facility means each of the following as defined in this section:
Cheswick; Conemaugh; Homer City; Keystone; and Montour.
    Facility-Wide 30-Day Rolling Average NOX Emission Rate for the
Facility shall be expressed in lb/MMBtu and calculated in accordance
with the following procedure: First, sum the total pounds of
NOX emitted from all Units during the current Operating Day
and the previous twenty-nine (29) Operating Days; second, sum the total
heat input from all Units in MMBtu during the current Unit Operating
Day and the previous twenty-nine (29) Operating Days; and third, divide
the total number of pounds of NOX emitted from all Units
during the thirty (30) Operating Days by the total heat input during
the thirty (30) Operating Days. A new Facility-wide 30-Day Rolling
Average NOX Emission Rate shall be calculated for each new
Operating Day. Each 30-Day Rolling Average NOX Emission Rate
shall include all emissions that occur during all periods within any
Operating Day, including, but not limited to, emissions from startup,
shutdown, and malfunction.
    Fossil Fuel means any hydrocarbon fuel, including coal, petroleum
coke, petroleum oil, fuel oil, or natural gas.
    Homer City means, for purposes of this section, Homer City
Generation LP's Homer City Generating Station consisting of three coal-
fired units designated as Unit 1 (6,792 MMBtu/hr), Unit 2 (6,792 MMBtu/
hr), and Unit 3 (7,260 MMBtu/hr), located in Center Township, Indiana
County, Pennsylvania.
    Keystone means, for purposes of this section, Keystone Conemaugh
Project LLC's Keystone Generating Station consisting of two coal-fired
units designated as Unit 1 (8,717 MMBtu/hr) and Unit 2 (8,717 MMBtu/
hr), located in Plumcreek Township, Armstrong County, Pennsylvania.
    lb/MMBtu means one pound per million British thermal units.
    Montour means, for purposes of this section, Talen Energy
Corporation's Montour Steam Electric Station consisting of two coal-
fired units designated as Unit 1 (7,317 MMBtu/hr) and Unit 2 (7,239
MMBtu/hr), located in Derry Township, Montour County, Pennsylvania.
    NOX means oxides of nitrogen, measured in accordance with the
provisions of this section.
    NOX Emission Rate means the number of pounds of NOX
emitted per million British thermal units of heat input (lb/MMBtu),
calculated in accordance with this section.
    Operating Day means any calendar day on which a Unit fires Fossil
Fuel.
    Title V Permit means the permit required for major sources pursuant
to Subchapter V of the Act, 42 U.S.C. 7661-7661e.
    Unit means collectively, the coal pulverizer, stationary equipment
that feeds coal to the boiler, the boiler that produces steam for the
steam turbine, the steam turbine, the generator, the equipment
necessary to operate the generator, steam turbine, and boiler, and all
ancillary equipment, including pollution control equipment and systems
necessary for production of electricity. An electric steam generating
station may be comprised of one or more Units.
    Unit-specific Daily NOX Mass Emissions shall be expressed in lb/day
and calculated as the sum of total pounds of NOX emitted
from the Unit during the Unit Operating Day. Each Unit-specific Daily
NOX Mass Emissions shall include all emissions that occur
during all periods within any Operating Day, including emissions from
startup, shutdown, and malfunction.
    (f) NOX emission limitations. (1) The Facility shall achieve and
maintain their Facility-wide 30-Day Rolling Average NOX
Emission Rate to not exceed their Facility limit in Table 1 to this
paragraph (f)(1).

  Table 1 to Paragraph (f)(1)--Facility-Wide 30-Day Rolling Average NOX
                          Emission Rate Limits
------------------------------------------------------------------------
                                                       Facility-wide 30-
                                                          day rolling
                       Facility                           average NOX
                                                         emission rate
                                                        limit (lb/MMBtu)
------------------------------------------------------------------------
Cheswick.............................................              0.099
Conemaugh............................................              0.091

Homer City...........................................              0.088
Keystone.............................................              0.074
Montour..............................................              0.069
------------------------------------------------------------------------

    (2) The Facility shall achieve and maintain their Unit-specific
Daily NOX Mass Emissions to not exceed the Unit-specific
limit in Table 2 to this paragraph (f)(2).

   Table 2 to Paragraph (f)(2)--Unit-Specific Daily NOX Mass Emissions
                                 Limits
------------------------------------------------------------------------
                                                         Unit-specific
                                                         daily NOX Mass
                  Facility                      Unit    emissions limit
                                                            (lb/day)
------------------------------------------------------------------------
Cheswick....................................        1             14,256
Conemaugh...................................        1             18,084
Conemaugh...................................        2             18,084
Homer City..................................        1             14,345
Homer City..................................        2             14,345
Homer City..................................        3             15,333
Keystone....................................        1             15,481
Keystone....................................        2             15,481
Montour.....................................        1             12,117
Montour.....................................        2             11,988
------------------------------------------------------------------------

    (g) Monitoring of NOX emissions. (1) In determining the Facility-
wide 30-Day Rolling Average NOX Emission Rate, the Facility
shall use CEMS in accordance with the procedures of 40 CFR part 60 and
40 CFR part 75, appendix F, Procedure 1.
    (2) For purposes of calculating the Unit-specific Daily
NOX Mass Emissions Limits, the Facility shall use CEMS in
accordance with the procedures at 40 CFR part 75. Emissions rates, mass
emissions, and other quantitative standards set by or under this
section must be met to the number of significant digits in which the
standard or limit is expressed. For example, an emission rate of 0.100
is not met if the actual emission rate is 0.101. The Facility shall
round the fourth significant digit to the nearest third significant
digit, or the sixth significant digit to the nearest fifth significant
digit, depending upon whether the limit is expressed to three or five
significant digits. For example, if an actual emission rate is 0.1004,
that shall be reported as 0.100, and shall be in compliance with an
emission rate of 0.100, and if an actual emission rate is 0.1005, that
shall be reported as 0.101, and shall not be in compliance with an
emission rate of 0.100. The Facility shall report data to the number of
significant digits in which the standard or limit is expressed.
    (h) Recordkeeping and periodic reporting. (1) The Facility shall
electronically submit to EPA a periodic report, within thirty (30) days
after the end of each six-month reporting period (January through June,
July through December in each calendar year). The portion of the
periodic report containing the data required to be reported by this
paragraph (h) shall be in an unlocked electronic spreadsheet format,
such as Excel or other widely-used software, and contain data for each
Operating Day during the reporting period, including, but not limited
to: Facility ID (ORISPL); Facility name; Unit ID; Date; Unit-specific
total Daily Operating Time (hours); Unit-specific Daily NOX