[Federal Register Volume 87, Number 101 (Wednesday, May 25, 2022)]
[Proposed Rules]
[Pages 31798-31814]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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 (215) 814-2117. 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

[[Page 31799]]

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

[[Page 31800]]

``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.

[[Page 31801]]

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

[[Page 31802]]

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\
---------------------------------------------------------------------------

    \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

[[Page 31803]]

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

[[Page 31804]]

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

[[Page 31805]]

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.

[[Page 31806]]



                                   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

[[Page 31807]]

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

[[Page 31808]]

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

[[Page 31809]]

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

[[Page 31810]]

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

[[Page 31811]]

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

[[Page 31812]]

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:

[[Page 31813]]

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

[[Page 31814]]

 
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 
Mass Emissions (lbs); Unit-specific total Daily Heat Input (MMBtu); 
Unit-specific Daily NOX Emission Rate (lb/MMBtu); Facility-
wide 30-Day Rolling Average NOX Emission Rate (lb/MMBtu); 
Owner; Operator; Representative (Primary); and Representative 
(Secondary). In addition, the Facility shall maintain the following 
information for 5 years from the date of creation of the data and make 
such information available to EPA if requested: Unit-specific hourly 
heat input, Unit-specific hourly ammonia injection amounts, and Unit-
specific hourly NOX emission rate.
    (2) In any periodic report submitted pursuant to this section, the 
Facility may incorporate by reference information previously submitted 
to EPA under its Title V permitting requirements in this chapter, so 
long as that information is adequate to determine compliance with the 
emission limits and in the same electronic format as required for the 
periodic report, and provided that the Facility attaches the Title V 
Permit report (or the pertinent portions of such report) and provides a 
specific reference to the provisions of the Title V Permit report that 
are responsive to the information required in the periodic report.
    (3) In addition to the reports required pursuant to this section, 
if the Facility exceeds the Facility-wide 30-day rolling average 
NOX emission limit on three or more days during any 30-day 
period, or exceeds the Unit-specific daily mass emission limit for any 
Unit on three or more days during any 30-day period, the Facility shall 
electronically submit to EPA a report on the exceedances within ten 
(10) business days after the Facility knew or should have known of the 
event. In the report, the Facility shall explain the cause or causes of 
the exceedances and any measures taken or to be taken to cure the 
reported exceedances or to prevent such exceedances in the future. If 
at any time, the provisions of this section are included in Title V 
Permits, consistent with the requirements for such inclusion in this 
section, then the deviation reports required under applicable Title V 
regulations in this chapter shall be deemed to satisfy all the 
requirements of this paragraph (h)(3).
    (4) Each report shall be signed by the Responsible Official as 
defined in Title V of the Clean Air Act, or his or her equivalent or 
designee of at least the rank of Vice President. The signatory shall 
also electronically submit the following certification, which may be 
contained in a separate document:

    This information was prepared either by me or under my direction 
or supervision in accordance with a system designed to assure that 
qualified personnel properly gather and evaluate the information 
submitted. Based on my evaluation, or the direction and my inquiry 
of the person(s) who manage the system, or the person(s) directly 
responsible for gathering the information, I hereby certify under 
penalty of law that, to the best of my knowledge and belief, this 
information is true, accurate, and complete. I understand that there 
are significant penalties for submitting false, inaccurate, or 
incomplete information to the United States.

    (5) Whenever notifications, submissions, or communications are 
required by this section, they shall be made electronically to the 
attention of the Air Enforcement Manager via email to the following 
address: [email protected].

[FR Doc. 2022-10765 Filed 5-24-22; 8:45 am]
BILLING CODE 6560-50-P