Air Plan Disapproval; Pennsylvania; Reasonably Available Control Technology Case-by-Case Permits for Keystone, Conemaugh and Homer City Generating Facilities for the 1997 and 2008 Ozone National Ambient Air Quality Standards, 13022-13032 [2024-03528]
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Federal Register / Vol. 89, No. 35 / Wednesday, February 21, 2024 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R03–OAR–2024–0047; FRL–9920–01–
R3]
Air Plan Disapproval; Pennsylvania;
Reasonably Available Control
Technology Case-by-Case Permits for
Keystone, Conemaugh and Homer City
Generating Facilities for the 1997 and
2008 Ozone National Ambient Air
Quality Standards
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
The Environmental Protection
Agency (EPA) is proposing to
disapprove state implementation plan
(SIP) revisions submitted by the
Pennsylvania Department of
Environmental Protection (PADEP) on
behalf of the Commonwealth of
Pennsylvania (Pennsylvania). PADEP
submitted SIP revisions for the
Keystone, Conemaugh and Homer City
electric generating facilities on May 26,
2022 to address certain reasonably
available control technique (RACT)
requirements for the 1997 and 2008
ozone national ambient air quality
standards (NAAQS). EPA is proposing
to disapprove the May 26, 2022 SIP
revisions for these facilities as the SIPs
contain problematic provisions and fail
to justify the selection of permit limits
as RACT consistent with applicable
requirements and case law. This action
is being taken under the Clean Air Act
(CAA).
DATES: Written comments must be
received on or before March 22, 2024.
ADDRESSES: Submit your comments,
identified by Docket ID No. EPA–R03–
OAR–2024–0047 at https://
www.regulations.gov, or via email to
gordon.mike@epa.gov. For comments
submitted at Regulations.gov, follow the
online instructions for submitting
comments. Once submitted, comments
cannot be edited or removed from
Regulations.gov. For either manner of
submission, EPA may publish any
comment received to its public docket.
Do not submit electronically any
information you consider to be
confidential business information (CBI)
or other information whose disclosure is
restricted by statute. Multimedia
submissions (audio, video, etc.) must be
accompanied by a written comment.
The written comment is considered the
official comment and should include
discussion of all points you wish to
make. EPA will generally not consider
comments or comment contents located
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SUMMARY:
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outside of the primary submission (i.e.
on the web, cloud, or other file sharing
system). For additional submission
methods, please contact the person
identified in the FOR FURTHER
INFORMATION CONTACT section. For the
full EPA public comment policy,
information about CBI or multimedia
submissions, and general guidance on
making effective comments, please visit
https://www.epa.gov/dockets/
commenting-epa-dockets.
FOR FURTHER INFORMATION CONTACT:
Sean Silverman, Planning &
Implementation Branch (3AD30), Air &
Radiation Division, U.S. Environmental
Protection Agency, Region III, 1600 John
F. Kennedy Boulevard, Philadelphia,
Pennsylvania 19103. The telephone
number is (215) 814–5511. Mr.
Silverman can also be reached via
electronic mail at silverman.sean@
epa.gov.
SUPPLEMENTARY INFORMATION:
I. Background
The RACT requirements in CAA
section 182(b)(2) apply to all ozone
nonattainment areas classified as
Moderate or higher (i.e. Serious, Severe,
or Extreme). Section 184(b)(1)(B) of the
CAA also applies RACT to all areas
located within ozone transport regions.
The entire Commonwealth of
Pennsylvania is part of the Ozone
Transport Region (OTR) established by
section 184 of the CAA and therefore
subject statewide to RACT
requirements.
On May 16, 2016, Pennsylvania
submitted a SIP revision intended to
satisfy CAA sections 182(b)(2)(C), 182(f),
and 184 for the 1997 and 2008 8-hour
ozone NAAQS for all major sources of
nitrogen oxides (NOX) and volatile
organic compounds (VOCs) in
Pennsylvania not subject to control
techniques guidelines (CTGs), with a
few exceptions not relevant to this
action. On May 9, 2019, EPA published
a final action fully approving certain
provisions and conditionally approving
other portions of Pennsylvania’s May
16, 2016, SIP submission to implement
RACT for the 1997 and 2008 Ozone
NAAQS (hereafter the ‘‘RACT II rule’’).
84 FR 20274 (May 9, 2019). Specifically,
EPA’s action fully approved sections
121.1, 129.96, 129.97, and 129.100 of
Title 25 of the Pennsylvania Code (25
Pa. Code) as meeting certain aspects of
major stationary source RACT in CAA
sections 172, 182, and 184 for the 1997
and 2008 ozone NAAQS, and
conditionally approved 25 Pa. Code
sections 129.98 and 129.99 following a
commitment provided by Pennsylvania
to submit additional SIP revisions to
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address the deficiencies identified by
EPA in the May 16, 2016 SIP revision.
Id. at 20290.
On August 27, 2020, the Third Circuit
held unlawful and vacated EPA’s
approval of certain SIP provisions
challenged by the Sierra Club. Sierra
Club v. EPA, 972 F.3d 290 (3rd Cir.
2020) (‘‘Sierra Club’’). The case related
to EPA’s approval of only that portion
of the RACT II rule applicable to coalfired electricity generating units (EGUs)
equipped with selective catalytic
reduction (SCR) for control of NOX.
Specifically at issue was EPA’s approval
of the presumptive RACT NOX limit for
these EGUs of 0.12 pounds of NOX per
Million British Thermal Units (MMBtu)
of heat input (lbs/MMBtu) when the
inlet temperature to the SCR was 600
degrees Fahrenheit or above, found at 25
Pa. Code 129.97(g)(1)(viii); the
application of the less stringent NOX
limits of 25 Pa Code 129.97(g)(1)(vi) to
EGUs with SCR when the inlet
temperature to the SCR was below 600
degrees Fahrenheit; and the failure of
the RACT II rule at 25 Pa. Code
129.100(d) to specifically require these
EGUs to keep temperature data for the
inlet temperature to the SCRs and report
that data to PADEP.
The Court explained that, while
RACT does not require the lowest
achievable emissions limit,
Pennsylvania’s adoption of a limit
derived from the average historical NOX
emissions of the units at these EGUs,
without more, was insufficient. The
record showed that certain units within
Pennsylvania were capable of achieving
significantly lower rates of NOX
emissions. The Court found that EPA
did not sufficiently explain why a lower
standard was infeasible. Sierra Club,
972 F.3d at 299–303. Second, the Court
held that Pennsylvania’s standard acted
as a loophole because it permitted
unlimited operations without the use of
SCR controls if exhaust gas temperature
was kept below what the Court
considered an arbitrary temperature
threshold of 600 degrees Fahrenheit. Id.
at 303–07. Third, the Court held that
Pennsylvania’s reporting requirements
were not enforceable. Id. at 307–09.
Consequently, the Court vacated
EPA’s approval of this portion of the
2016 SIP and ordered EPA either to
approve a revised, compliant SIP or
promulgate a FIP within two years (i.e.,
by August 27, 2022). Sierra Club at 309.
The Court stated that the new
standard—SIP or FIP—‘‘must be
technology forcing, in accord with
[EPA’s] RACT standard, and lack the
gaping loophole found in the [2016
SIP’s] enforcement regime.’’ Id. On
August 16, 2022, EPA took final action
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to disapprove the vacated portions of
the May 19, 2020 approval. 87 FR
50257. EPA published its proposed FIP
on May 25, 2022. 87 FR 31798. EPA
issued a FIP on August 31, 2022. 87 FR
53381.
Following the Court’s decision,
PADEP required that by April 1, 2021,
each source within a facility which had
been subject to the presumptive 0.12 lb/
MMBtu limit submit a permit
application in accordance with 25 Pa.
Code 129.99 setting forth a RACT
analysis for each unit at the facility.1 On
or about April 1, 2021, Conemaugh,
Homer City, Keystone, and Montour
submitted permit applications to PADEP
with RACT analyses.2 PADEP found the
permit applications to be technically
deficient and therefore issued technical
deficiency letters to each of these
sources seeking additional information.
Although the sources submitted
additional information, PADEP decided
that it would do its own case-by-case
RACT analysis for each EGU at each
facility and propose new RACT limits
for each EGU in amended title V
permits. Once these permits became
final, PADEP intended to submit each
permit to EPA as a SIP revision to meet
the RACT requirement for each source.
EPA also continued to regularly discuss
with PADEP their efforts to develop
case-by-case RACT/title V permits for
these sources.
From September 11, 2021, through
November 6, 2021, PADEP serially
issued draft RACT/title V permits for
four sources, while Allegheny County
issued a draft RACT/title V permit for
Cheswick in December 2021.3 EPA
submitted timely comments on each
draft permit. Many of the concerns and
13023
two auxiliary boilers at Keystone
(Source IDs 037 and 038) and the two
at Conemaugh (Source IDs 039 and 041).
These auxiliary boilers were not subject
to the presumptive RACT limit in 25 Pa.
Code 129.97(g)(1)(viii) for which EPA
issued a final disapproval in August
2022.
issues identified in EPA’s first set of
comments (which was on the Keystone
permit) appeared again in the draft
permits for the other sources. EPA’s
comments raised significant concerns
over the approvability of each permit
because each remained inconsistent
with the court’s decision, and PADEP
did not address those concerns with
each subsequent draft permit it
published for comment. On May 26,
2022, PADEP submitted case-by-case
RACT determinations to EPA as a
revision to the Pennsylvania SIP which
still contained the approvability issues
EPA had flagged in its comments, for
Keystone, Conemaugh, and Homer City.
PADEP submitted a case-by-case RACT
determination for Montour as a revision
to the Pennsylvania SIP on June 9, 2022,
but subsequently formally withdrew it.4
In addition, the Cheswick facility
permanently ceased operations and
surrendered all of its air permits to the
Allegheny County Health Department.5
The Homer City facility also ceased all
coal-burning operations on July 1,
2023.6 Prior to July 1st, only Unit 3 at
Homer City was operating. However,
because Homer City has not formally
surrendered its CAA permits, which
would demonstrate that the shutdown is
permanent, and because PADEP has not
withdrawn the SIP submission with
regard to Homer City, EPA will continue
to consider the approvability of the
RACT NOX limits for Homer City.
EPA notes that the May 2022 permits
for Keystone and Conemaugh also
contain case-by-case RACT limits for
certain gas or oil-fired auxiliary boilers
at these facilities. However, EPA is not
taking action at this time on the case-bycase RACT limits in these permits for
II. Summary of the Case-by-Case Permit
SIP Revisions
EPA notes that the RACT limits in
PADEP’s May 2022 SIP submittal
addressed RACT limits for the large
Electric Generating Units (EGUs) at
Conemaugh, Keystone, and Homer City
for only the 1997 and 2008 ozone
NAAQS. These source-specific limits
were established pursuant to 25 Pa.
Code 129.99, which was conditionally
approved by EPA in March 2019.
Section 129.99 of 25 Pa. Code allows a
source to apply for an alternative RACT
limit (a.k.a. ‘‘case-by-case’’ RACT limit)
to the otherwise default (a.k.a.
‘‘presumptive’’) RACT limits where
appropriate. In response to comments,7
PADEP affirmed that the RACT limits
for the EGUs at these three sources do
not address the 2015 ozone NAAQS.8
Summary of Pennsylvania’s Process for
Setting Limits
PADEP developed the NOX limits for
each of the EGUs at each facility using
a similar methodology, which included
using similar years of data. Table 1 in
this document summarizes the three
NOX emission rates applicable to each
unit at each facility as proposed by
Pennsylvania for public comment, and
the final limits in the permits submitted
by PADEP for approval as SIP revisions.
TABLE 1—PROPOSED RATES AND FINAL RATES IN 2022 PA SIP SUBMISSION
Proposed limits
Facility
Conemaugh ....................................
Keystone .........................................
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Homer City ......................................
Unit
1
2
1
2
1
2
3
Capacity
.......
.......
.......
.......
.......
.......
.......
8,280
8,280
8,717
8,717
6,792
6,792
7,260
1 See ‘‘Conemaugh RACT II Review Memo’’ p. 2,
‘‘Homer City RACT II Review Memo’’ p. 3 and
‘‘Keystone RACT II Review Memo’’ p. 2, available
in the docket of this action.
2 The Bruce Mansfield EGUs ceased all operations
prior to April 1, 2021 and therefore did not submit
a RACT permit application.
3 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
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SCR on
lb/MMBtu
daily avg.
0.070
0.070
0.080
0.080
0.080
0.080
0.070
All
conditions
lb/MMBtu
daily avg.
Submitted as SIP revision (final)
All
conditions
lb/hr
30-day avg.
0.27
0.27
0.30
0.30
0.45
0.45
0.27
(Montour); Allegheny County Health Department
Public Notices, December 2, 2021 (Cheswick).
4 See document dated October 26, 2022 from EPA
Region III to Acting Secretary Ramez Ziadeh of
PADEP available in the docket of this action.
5 See document dated April 15, 2022 from
Allegheny County to Lee Bahl of GenOn Holdings
LLC available in the docket of this action.
6 See https://www.pjm.com/planning/servicerequests/gen-deactivations.
7 All three Response to Comments (RTC)
documents are in the docket for this matter. The
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SCR on
lb/MMBtu
daily avg.
700
700
800
800
550
550
510
0.070
0.070
0.080
0.080
0.080
0.080
0.070
All
conditions
lb/MMBtu
daily avg.
0.27
0.27
0.30
0.30
0.45
0.45
0.27
All
conditions
lb/hr
30-day avg.
700
700
770
770
600
600
560
Conemaugh Response to Comments (Con RTC) and
Keystone Response to Comments (Key RTC) are
both dated May 12, 2022. The Homer City Response
to Comments (HC RTC) in the official SIP
submission is marked ‘‘Draft’’ and does not contain
a date.
8 See, e.g., Conemaugh Response to Comments, p.
2: ‘‘incorporates the provisions and requirements
contained in the amended RACT II approval for the
facility, which are intended to satisfy the [CAA]
RACT requirements for the 1997 and 2008 . . .
ozone [NAAQS].’’
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A technical evaluation memo (TEM)
accompanying each draft permit issued
for public comment provided an initial
explanation for PADEP’s methodology
for determining the proposed RACT
level of controls for each facility.9 For
each unit at each facility, PADEP states
that it followed a ‘‘top-down’’ approach
to determine NOX emissions limits,
which included searching for and
identifying the ‘‘best methodology,
technique, technology, or other means
for reducing NOX while factoring
environmental, energy and economic
considerations into the analysis.’’ Con
TEM, p. 2; Key TEM, p. 2; HC TEM, p.
2. This included identifying the controls
installed on coal-fired units in some
other states. PADEP then used the EPA
Control Cost Manual (sixth edition),
June 12, 2019, and sometimes vendor’s
quotes, to determine whether control
options PADEP identified as technically
feasible were also cost effective. Con
TEM, pp. 2–3; Key TEM, p. 2; HC TEM,
p. 3. PADEP performed some type of
analysis for multiple NOX control
technologies 10 for each facility before
‘‘determin[ing] that no additional
controls are cost effective.’’ Con TEM at
3. See, e.g., Con TEM pp. 3–19. In lieu
of new controls, PADEP determined that
for each of the three facilities, changes
to the way the facilities operated their
SCRs and changes to how they ‘‘tuned’’
the boilers were the only technically
available and cost-effective controls for
reducing NOX emissions. Con TEM, pp.
2–3; Key TEM, pp. 2–3; HC TEM, pp.
2–3. This approach resulted in PADEP
adopting three separate but related
limits for each EGU at each of the three
9 All three technical evaluation memos (TEMs)
are in the docket for this matter. The Homer City
technical evaluation memo (HC TEM) is dated
October 14, 2021. The Conemaugh technical
evaluation memo (Con TEM) is dated September 28,
2021. The Keystone technical evaluation memo
(Key TEM) is dated August 25, 2021.
10 Potential controls evaluated included:
Precombustion Controls (Switching to Natural Gas,
Switching from high to low emitting or zero
emitting units), Combustion Controls (Partial or full
oxy firing, Oxygen enhanced combustion, LNB
installation, LNB Optimization, LNB Upgrade, Flue
Gas Recirculation (FGR), Separated overfired air,
Rotating opposed fire air) Post Combustion Controls
(Additional SCR, SCR Optimization, Economizer
Bypass during low load, startup, and shutdown to
allow SCR operation, V-temp economizer during
low load, startup, and shutdown to allow SCR
operation, Flue gas reheat during low load, startup,
and shutdown to allow SCR operation, Dry sorbent
injection prior to SCR during low load conditions
to allow SCR operation, addition of Selective NonCatalytic Reduction (SNCR), SNCR Optimization,
Return of partially operating SCR and SNCR
systems to full operation) Station Wide
Improvements (Installation/improvement of digital
process controls on equipment to minimize NOX
emissions and detect equipment in need to
maintenance, Improved/increased equipment
cleaning and maintenance practices). See Con TEM
p. 4–19; Key TEM, pp 3–17; HC TEM pp. 3–21.
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facilities. The proposed and final rates
are in Table 1 of this document. The
method that PADEP used to arrive at
each of the three rates is summarized
below.
Selection of SCR-on lb/MMBtu Daily
Average Rates
To determine the ‘‘SCR-on’’ limit
representing RACT for when the SCRs
are operating, PADEP ‘‘analyzed daily
NOX emissions rates from EPA’s Clean
Air Markets Division (CAMD) database
at varying operating load conditions’’
for most of the units at each facility. Con
TEM, p. 3; HC TEM pp. 4–13; Key TEM
p. 3. PADEP examined data for each
facility ranging from 2016 to 2020,
depending on the facility.11 For certain
months within the 2016–2020 time
frame, PADEP states that it analyzed the
percentage of daily heat input and
corresponding percentage of daily
reagent injection for a unit or units at
each facility to ascertain how heat input
and reagent input affected daily NOX
emissions, and to determine the lowest
emission limit each unit could
technically and economically achieve
with the SCRs. PADEP’s analysis
included examining the percentage of
maximum heat rate input for the unit for
each day of certain months and the
corresponding percentage of maximum
ammonia (the reagent used) input
observed per day for the same month.
Con TEM, p. 4; Key TEM, pp. 3–8; HC
TEM pp. 4–13. From this data, PADEP
identified a ‘‘load’’ or heat input level
at which it seemed that Conemaugh
stopped injecting ammonia into the flue
gas stream, see Con. TEM, p. 6, but did
not identify loads or heat inputs at
which Homer City’s or Keystone’s units
stopped injecting ammonia. See HC
TEM pp. 4–13, Key TEM pp. 3–8.
PADEP also presented NOX emission
rate data for certain months for each
source during various ozone seasons,
and for some periods outside of ozone
seasons.12 For each facility, PADEP
found that the automated controls that
run the SCRs seemed to be set at an
emissions ‘‘set point,’’ expressed as
pounds of NOX per million Btus of heat
input (lb NOX/MMBtu), and that these
11 Note that Key TEM p. 3, Con TEM p. 3 and HC
TEM p. 4, state that the years reviewed are 2017–
2020, but Key RTC p. 8, Con RTC p. 9 and HC RTC
p. 7 state years reviewed were 2016–2020.
12 For Keystone, the months examined were May
2017 and April 2018. Key TEM pp. 3–6. For Homer
City, the months were June 2019 (unit 1), July of
2019 and 2020 (unit 2), and December 2017, July
2019, September 16, 2019 and Dec. 4, 2019 (unit 3).
HC TEM, pp. 4–14. For Conemaugh, dates
examined included May 2017, September 5, 2019,
and April 4, 2020. Con TEM pp. 3–8.
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set points varied over time.13 For
Conemaugh, PADEP concluded that
‘‘additional emission reductions would
be achieved if the operator operated the
SCR with a lower emissions setpoint
while the SCR is running.’’ Con. TEM,
p. 6. For Keystone, PADEP stated
‘‘[b]oth units at Keystone seem to be
able to achieve a NOX rate of 0.060 lb/
MMBtu on a daily average basis,’’ but
cited ‘‘varying load conditions and other
factors’’ as affecting SCR performance
and therefore proposed (and finalized) a
daily average SCR-on rate of 0.08 lb/
MMBtu for both. Key TEM, p. 6. PADEP
does not provide further information on
what these other factors are or what
impact they and load conditions would
have that lead to the selection of the
0.08 lb/MMBtu limit. For Homer City
units 1 and 2, PADEP’s analysis
concluded that the facility seemed to be
targeting a NOX emission rate of 0.10 lb/
MMBtu when the SCRs were operating,
but identified ‘‘rare’’ periods where the
units achieved rates below 0.05 lb/
MMBtu. HC TEM, p. 5. However,
PADEP concluded that ‘‘[d]espite the
fact that emissions under 0.10 lb/
MMBtu are possible under at least some
operating conditions, accounting for
other operating condition requires a
limit above the minimum achievable.’’
HC TEM, p. 8. PADEP therefore
proposed (and finalized) a 0.080 lb/
MMBtu daily average operating rate for
Units 1 and 2 when the SCR is
operating. For Unit 3, PADEP found that
it was also targeting a NOX emission rate
of 0.10 lb/MMBtu, but during July 2019
was able to consistently achieve NOX
rates between 0.08 and 0.09 lb/MMBtu
despite daily load swings. HC TEM, p.
9–10. PADEP identified two other
instances where Unit 3 was capable of
achieving NOX rates lower than 0.08,
but did not identify the lowest
achievable SCR-on rate before
determining that other factors require a
limit above the lowest achievable NOX
rate.14 Without identifying the lowest
achievable NOX emission rate or
explaining how the other factors affect
that rate, PADEP proposed (and
finalized) a rate of 0.07 lb/MMBtu when
the SCR is operating. HC TEM, pp. 12–
13.
Certain changes made to PADEP’s
proposed rates for each source in
response to comments received are
discussed in EPA’s analysis of the final
rates.
13 Con TEM, pp. 3–8; Key TEM, pp. 3–7; HC TEM,
pp. 4–13.
14 The other factors PADEP cites are varying
loads, operating load, catalyst condition, exhaust
temperature and velocity, moisture level, initial
NOX levels in the exhaust, and other unnamed
factors. HC TEM, p. 13.
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Selection of All Conditions lb/MMBtu
Daily Average Rate
The lb/MMBtu limits in the ‘‘All
Conditions lb/MMBtu Daily Average’’
columns of Table 1 in this document,
represent the daily average NOX limits
that PADEP determined each unit at
each facility could achieve solely
through the operation of its existing
low-NOX burners with overfire air, so
long as the sources ‘‘tuned’’ their boilers
to optimize the reduction of NOX rather
than to obtain the highest heat output.
PADEP describes boiler tuning as
making a number of adjustments to the
boiler operating parameters that affect
the generation of NOX in the boiler fire
box, including excess air levels,
secondary air biasing, fuel/auxiliary air
damper adjustments, burner tilt, fuel
flow biasing, and changes to primary air
flows. See, e.g., Con. TEM, pp. 14–15.
As stated in the technical evaluation
memo for Conemaugh, ‘‘[g]enerally
boiler’s regular inspection, preventive
maintenance, tuning, practicing during
shutdown and upset conditions to
prevent excess emissions, inspections
and testing of Over Fire Air (OFA)
components, and adjusted of burner
angle to minimize NOX emissions
results in lowering NOX emissions by 5–
15% or at an average of 10. %. [sic]’’
Con. TEM, p. 15. For each of the EGU
boilers (units) at each of the facilities,
PADEP determined that the boiler
burners had not been tuned to minimize
NOX emissions, but rather had been
tuned to maximize output. Key TEM, p.
13; HC TEM, p. 15; Con TEM, pp. 14–
15. For each facility, PADEP concluded
that tuning the boilers to minimize NOX
emissions could result in lowering NOX
emissions by 5% to 15%, so PADEP
elected to apply an average NOX
reduction of 10% when setting the ‘‘All
Conditions lb/MMBtu Daily Average’’
rate. Id.
Selection of All Conditions 30-Day
Rolling Average lb/hr Rate
Regarding the 30-day rolling average
pounds of NOX/hour limits in the
column in Table 1 labeled ‘‘All
Conditions lb/hr 30-day Average,’’ there
is some ambiguity in how PADEP
arrived at the final rates for Keystone
and Conemaugh. In the Keystone RTC,
PADEP states the 30-day lb/hr limit was
‘‘derived from the emission level at 0.08
lb/MMBTU at full load . . . with an
additional small margin to account for
the fact that it is impossible to
completely avoid all periods of
operation when complying with the
0.080 lb/MMBtu is technically
infeasible.’’ Key RTC, p. 10. Similar
language stating that the 30-day lb/hr
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rate was derived from the daily SCR-on
rates is also in Con RTC p. 11 and HC
RTC p. 9. PADEP’s explanation for how
the 30-day lb/hr limits were derived in
the Technical Evaluation Memos is
more ambiguous and does not explicitly
state the 30-day lb/hr rate is derived
from the daily SCR-on lb/MMBtu rate. A
description of what PADEP did in the
Technical Evaluation Memos is outlined
below.
PADEP seems to have generally
performed a similar analysis of similar
years of data for all three facilities, but
used a different method to set the 30day lb/hr rates for Conemaugh and
Homer City than for Keystone. For each
source at each facility, PADEP says it
analyzed ‘‘mass-based NOX emission
rate in pounds per hour on a 30
operational day rolling average basis
using EPA’s CAMD database at all
operating conditions for [the units] from
2017–2020. Mass based emission rate on
a 30 operational day rolling average
basis is dependent on number of hours
a unit is operated, on average, at high
load vs low load for the past 30-days
[sic].’’ 15 Con TEM p. 15; see also Key
TEM pp. 13–14, HC TEM pp. 17–19.
Following this analysis for each
facility, for Conemaugh and Homer City
PADEP used the SCR-on lb/MMBtu rate
for each unit at each facility, then
multiplied that SCR-on rate by each
unit’s maximum MMBtu per hour rating
to arrive at the number of pounds per
hour that each unit would emit if they
ran at their full heat input rating while
complying with that unit’s SCR-on lb/
MMBtu rate. For example, the technical
review memo for Conemaugh explains
that:
‘‘Each of Conemaugh’s units emits about
580 lb NOX per hour assuming an emission
level of .070 lb/MMBtu and 100% load. The
impact to the environment should never
exceed this level on a long-term basis. The
Department is proposing a limit of 700 lb/hr
limit on a 30 operational day rolling basis
which accounts for all operating scenarios
including situations during which the SCR is
not able to operate. The compliance buffer
also accounts for the fact that both units at
Conemaugh operate as much as 10% over
their rated capacity.’’ (Con TEM, p.15).
For Conemaugh, PADEP concluded
that Units 1 and 2 were operating
between 55% and 100% load during
this time and both were able to achieve
at or below 625 lb/hr on a 30-operating
day basis. PADEP found that during this
time period both units operated at
15 The Conemaugh TEM does not show the results
of the full analysis of the 2017–2020 data. For
example, Figure 6 in the Con TEM shows only
ozone season operating load versus 30-day rolling
average NOX emissions on a lb/hr basis for the 2017
ozone season. Con TEM, p. 6.
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around a 0.075 lb/MMBtu NOX
emissions rate, with occasional higher
spikes in rate. Based on this data,
PADEP concluded:
‘‘Given that the Department believes that
NOX rates below .07 are readily achievable
with the SCR in operation, and the fact that
both units were able to achieve a 30-day
rolling NOX rate of under 625 lb/hr despite
operating at a rate between .075 and .1, DEP
believes that Conemaugh Generating Station
can achieve a NOX rate of 700 lb/hr on a 30day rolling basis. Even if the facility were to
operate at low load for a significant time
during a 30-day averaging period—generating
significantly more mass emissions than
operation at higher loads with SCR, emission
rates at high load should be significantly
below 700 lb/hr allowing the facility to
‘‘make up’’ for higher emissions during times
of low load, assuming the facility operates to
the NOX rate of .045–.05 lb/MMBtu it is
usually capable of meeting when the SCR is
operating.’’ Con TEM, pp. 16–17.
Thus, for Conemaugh, PADEP proposed
and finalized an all conditions 30-day
rolling average lb/hr limit of 700 lb/hr.
For Homer City, PADEP used the
proposed SCR-on daily average NOX
limit of 0.08 lb/MMBtu for Units 1 and
2, multiplied by the maximum MMBtu
per hour for each of these units, to
arrive at a 30-day rolling average limit
of 550 lb of NOX per hour for each unit.
For Unit 3, PADEP used the proposed
SCR-on lb/hr daily average limit of 0.07
lb/MMBtu multiplied by the maximum
heat input for Unit 3 to arrive at a
rolling 30-day average limit of 510 lbs
of NOX per hour. HC TEM, p. 17. In
response to a comment from Homer
City, PADEP raised the 30-day rolling
average lb/hr limits to 600 lb/hr for
Units 1 and 2 and 560 lb/hr for unit 3.
For Keystone, PADEP appears to have
arrived at its proposed and final 30-day
rolling average lb/hr limit through a
different method. PADEP’s TEM states
that PADEP analyzed the mass-based
NOX emission rate pounds per hour on
a 30-day rolling average at all operating
conditions for Units 1 and 2 from 2017–
2020. Key TEM, p. 13. The TEM then
provides Figure 5, which graphs the 30day rolling NOX rates for Units 1 and 2,
but only for the 2017 ozone season. Key
TEM. P. 14. From Figure 5, the TEM
concludes that both units were able to
achieve at or below 800 lbs/hr on a 30day rolling average basis, continuously.
Key TEM, p.14. The TEM then asserts
that based on the CAMD data, ‘‘DEP
believes that by managing combination
of hours of operations when a unit is
operating at loads supporting SCR and
at lower loads with [low NOX burners],
Unit 1 and Unit 2 can achieve 800 lbs/
hr on a 30-day operating day rolling
average basis despite the changes in
utilization of the boiler.’’ Id. From this,
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PADEP concluded that the 800 lb/hr 30day rolling average limit under all
operating conditions is RACT. Id.
However, in response to comments, this
limit was changed to 770 lbs/hr for both
units. Key RTC pp. 6.
In the response to comments
document for Conemaugh, PADEP
explained that the 30-day rolling
average lbs/hr all conditions rate ‘‘. . .
is the glue that holds the three emission
limits together and ensures that the
emission reductions from the two
Conemaugh Generating Station units are
maximized . . . This emission limit
applies at all times and in all
circumstances, without exception.’’ Con
RTC, p. 6. 16 PADEP further asserts that
the SCR-on lb/MMBtu daily average rate
minimizes the emissions that occur
when operating with the SCR, while
also claiming that the 30-day rolling
average lb/hr all conditions rate
minimizes ‘‘both the amount of time
that the units can be operated when the
SCR is technically unavailable, as well
as forces the load (and therefore mass
emission rate) to the lowest rate possible
when it is not being operated due to
technical unavailability.’’ See, e.g. Con
RTC, p. 6. The RTC further explains that
‘‘[a]t any load above approximately
30%–40%, operation without control by
the SCR results in emissions greater
than 700 lbs/hr. As the load climbs, the
emissions per hour climb
proportionately.’’ Id. PADEP asserts that
the 700 lb/hr rolling 30-day average
limit ‘‘ensures that the operator will
maximize operating hours with the SCR
and minimize heat input (and total mass
emissions) when operation of the SCR is
technically infeasible.’’ Id.
III. EPA’s Evaluation of the RACT
Permit Limits in the SIP Submittals
EPA’s review of the RACT permit
limits in each of the three case-by-case
RACT permits submitted as SIP
revisions by PADEP has identified
several issues appearing in each permit
which preclude approval of the SIP
submissions as satisfying RACT
requirements. In summary, EPA has
determined that there are issues
regarding the enforceability of the SCRon permit limits, Director’s discretion
issues related to the SCR-on limits, and
an inadequate justification for why the
SCR-on limits meet the definition of
RACT for each source. Moreover,
because some of the 30-day rolling
hourly average pound per hour mass
limits appear to be derived from the
daily lb/MMBtu SCR-on limits, the
failure of the SCR-on limit to meet the
16 Nearly identical statements are in Key RTC p.
6 and HC RTC p. 6.
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criteria for RACT calls into question
whether the 30-day limits are RACT.17
Also, EPA cannot verify from PADEP’s
submitted SIPs whether these 30-day
rolling average pound per hour mass
limits actually act as a constraint on
operation of the EGUs without operation
of the SCRs in a way that represents
RACT. In addition, PADEP has added a
‘‘compliance margin’’ buffer to the 30day rolling average pound per hour
limits without an adequate explanation
of why that buffer is necessary to make
the limits technologically or
economically feasible. Each of these
issues is discussed below. As a result,
EPA is proposing to disapprove this SIP
revision.
Lack of Enforceability of the ‘‘SCR-On’’
Limits for Each EGU at Each Facility
Neither the permits nor the
background information submitted with
the SIP set forth clear, objective criteria
for determining when emissions from
each EGU are subject to the SCR-on lb/
MMBtu daily average limit(s). As such,
it is not possible in all circumstances for
EPA or the public to determine whether
this limit applies, and therefore whether
the sources are in noncompliance with
that limit. As a result, EPA is proposing
to disapprove the PADEP SIP revision
on this basis.
Each permit includes language stating
the NOX emissions are limited at a
certain level, but that certain emissions
are excluded when evaluating whether
the limitations are met. Specifically, the
permits contain exclusions for:
‘‘. . . emissions during start-up, and shutdown; operation pursuant to emergency
generation required by PJM, including any
necessary testing for such emergency
operations; and during periods in which
compliance with this emission limit would
require operation of any equipment in a
manner inconsistent with technological
limitations, good engineering and
maintenance practices, and/or good air
pollution control practices for minimizing
emissions.’’ See, e.g., Conemaugh final
permit, Section E, Restrictions, #001, p. 176.
Keystone Final Permit, p. 169, and Homer
City Final Permit p. 134.18
17 In Key RTC p. 10 PADEP states the 30-day lb/
hr limit was ‘‘derived from the emission level at
0.08 lb/MMBTU at full load . . . with an additional
small margin . . .’’ Similar language stating that the
30-day lb/hr rate was derived from the daily SCRon rates is also in Con RTC p. 11 and HC RTC p.
9. PADEP’s explanation for how the 30-day lb/hr
limits were derived in Key TEM pp. 13–14, Con
TEMP pp. 15–17 and HC TEM pp. 17–19 is more
ambiguous and doesn’t explicitly state the 30-day
lb/hr rate is derived from the daily SCR-on lb/
MMBtu rate as noted under the ‘‘Selection of All
Conditions 30-day Rolling Average lbs/hr Rate’’
heading in section II.
18 PJM is the Pennsylvania-New Jersey-Maryland
Interconnection, a regional transmission
organization operating in the midatlantic states.
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EPA has determined that the
exclusion during ‘‘Operation pursuant
to emergency generation required by
PJM’’ is problematic. This condition is
not defined in the permit for Homer City
but is defined in the final permits for
Conemaugh (p. 176) and Keystone
(p.169), stating that ‘‘the emissions limit
remains in effect unless the permittee
demonstrates that compliance with the
[applicable emission limitation] is
technically infeasible.’’ There are no
bounds or explanation in the permit
regarding what would equate to
technical infeasibility, nor is there
information on whom the permittee
would demonstrate this infeasibility to
or how EPA or the public could
determine whether such an adequate
demonstration was made. In response to
comments, PADEP stated:
‘‘the Conemaugh Station permit includes a
process where emissions can be requested for
exclusion from calculation of the 0.070 lb/
MMBtu emission limit if the owner/operator
makes a demonstration of technical
infeasibility to the Department’s satisfaction.
The general factors that may lead to technical
infeasibility are included in the Conemaugh
Station permit, and mirror SIP-approved
RACT regulations in neighboring states. In
fact, the list of general factors in
Conemaugh’s permit is more limited than the
factors listed in regulations promulgated by
one commentator. See COMAR 26.11.38.04
section 4.’’ 19 Con RTC, p. 3.
EPA did not find the suggested list of
‘‘general factors’’ which may lead to a
determination of technical infeasibility.
EPA also notes that this type of posthoc determination allowing the director
to grant exemptions from a SIPapproved emission limit during periods
of startup, shutdown or other periods is
the type of director’s discretion
prohibited by the CAA, for the reasons
set forth in EPA’s 2015 startup,
shutdown and malfunction (SSM) SIP
Action. 80 FR at 33840, 33917 (June 12,
2015). As stated in the 2015 SSM SIP
Action, ‘‘SIP provisions cannot contain
director’s discretion to alter SIP
requirements, including those that allow
for variances or outright exemptions for
emissions during SSM events.’’ 80 FR at
33917. In the case of the permits
submitted as part of Pennsylvania’s
2022 SIP revision, each contains
language that allows the director to
decide whether or not emissions from a
source during any hour should be
counted towards the more stringent
SCR-on emission limits of 0.07–0.08 lb/
MMBTU or to the less stringent
emission limits of 0.27–0.45 lb/
MMBTU. Although the rates would not
change, the director would be making a
19 COMAR
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decision as to whether certain emissions
should be exempted from the more
stringent SCR-on lb/MMBtu 24-hour
average rate. This is the type of
unilateral, ad hoc (or post hoc) decision
by the director which could negate the
possibility of enforcement of an
otherwise enforceable SIP emission
limit by EPA or the public and which
is barred by EPA as first established in
the 1999 SSM Guidance. 1999 SSM SIP
guidance at 3, 80 FR 33840 at 33917.
In addition, pursuant to EPA’s
responsibilities under sections
110(k)(3), 110(l) and 193 of the CAA, the
Agency cannot approve a SIP provision
that automatically preauthorizes the
state to unilaterally revise the SIP
emission limit (in this case by making
determinations that it did not apply at
certain times) without meeting the
applicable procedural and substantive
statutory requirements for SIP revisions.
80 FR at 33918. As stated in EPA’s 2015
SSM SIP Action, ‘‘[i]t is a fundamental
tenet of the CAA that states cannot
unilaterally change SIP provisions,
including the emission limitations
within SIP provisions, without the
EPA’s approval of the change through
the appropriate process.’’ Id.
In the quoted response to comments
on this issue, PADEP claims that the list
of general factors in the permits (which
EPA could not locate) are more limited
than factors listed in Maryland’s
regulations. EPA notes that it has not
approved the cited Maryland regulation,
COMAR 26.11.38.04, as RACT for EGUs,
so the cited example does not carry any
weight in EPA’s analysis of this SIP
revision.20 PADEP claims that the list of
general factors (which again, EPA could
not locate) ‘‘mirror SIP-approved RACT
regulations in neighboring states,’’ but
PADEP does not identify these other
SIP-approved RACT regulations and
EPA is not aware of what PADEP may
be referencing. Without knowing which
SIP-approved RACT regulations PADEP
is referring to, EPA cannot judge the
relevance of this argument.
The exclusion for ‘‘periods in which
compliance with this emission limit
would require operation of any
equipment in a manner inconsistent
with technological limitations, good
engineering practices, and/or good air
pollution control practices . . .’’ is also
problematic. No permit provides
20 See the final document at 82 FR 24546 (May
30, 2017) approving the NOX limits for Maryland’s
EGUs as SIP strengthening measures, and the final
document at 84 FR 5004 (February 20, 2019)
approving Maryland’s RACT regulations for
controlling VOC major sources for the 2008 ozone
NAAQS, which notes that Maryland will address
major sources of NOX in another SIP. None of the
VOC regulations approved included the language in
COMAR 26.11.38.04.
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additional definitions or instruction on
how this provision should be
interpreted or applied. Similar to other
provisions at issue here, this lack of
definition makes this exemption
provision difficult or impossible to
enforce.
Although the permits require that the
sources keep certain data and submit a
monthly report to PADEP, it is in the
sources’ discretion to identify in these
monthly reports ‘‘whether or not they
believe they are subject to the [SCR-on]
lb NOX/MMBtu limit’’ and ‘‘clearly
document how [they] determined
whether or not they believe they are
subject to the [SCR-on] lb NOX/MMBtu
hourly limit.’’ 21 But this does not
explain how PADEP will determine
whether certain hours of NOX emissions
from the sources should be counted
towards the SCR-on daily average lb/
MMBtu limits for each source, or the
circumstances under which these
emissions would be excluded from the
limit. It is even more difficult to
understand how EPA or the public
would discern which hours of emissions
should be counted towards the SCR-on
limit. If it is unknown which hours of
emissions count, it is impossible to
determine whether a source complied
with the SCR-on limit. In other words,
without clear and objective criteria for
excluding these emissions, neither EPA
nor the public could determine whether
the sources were complying with the
SCR-on limit at each source. Although
this situation is somewhat different than
the situation faced by the Third Circuit
in the Sierra Club appeal (lack of
adequate recordkeeping), the lack of
objective criteria for determining
compliance in this situation leads to the
same problem identified by that court,
which is that there is no way for
interested members of the public or EPA
to conduct oversight. Sierra Club at 307.
Pennsylvania’s Inadequate Justification
of Certain Limits as RACT
EPA understands the PADEP’s
submission to argue that RACT for these
facilities is comprised of: (1) a low daily
SCR-on lb/MMBtu limit with exclusions
as outlined in the prior section; (2) a
21 Conemaugh final permit, p. 177. The final
unredacted permits for all three facilities also state
that the monthly reports should include the hourly
load levels, heat input, ammonia injection rates,
NOX rates, total NOX emissions, the SCR emission
set point, SCR inlet and outlet temperature, and
clearly indicate any days which the SCR-on lb/
MMBtu emission limit is exceeded. For days
exceeding the SCR-on lb/MMBtu limit, the above
information must be provided on an hourly basis
and the permittee must give a detailed explanation
for why they exceeded their emission limit.
Conemaugh permit, p. 176, Keystone permit pp.
170–171, Homer City permit p. 137.
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much higher all conditions daily lb/
MMBtu limit that provides a
permissible emissions level under all
operating conditions including when
the SCR is not operating; and (3) the 30day rolling average all conditions lb/hr
limit, which is intended to provide
some restriction on the extent to which
the source could claim exclusions from
the SCR-on rate. EPA has identified
issues with each of these limits as
discussed in the subsections below. EPA
does allow for the possibility that
different or alternative emissions limits
(AELs) can apply during different
modes of operation in the manner that
PADEP has done here for the three
different limits described.22 However,
EPA has stated that those AELs ‘‘must
be clearly stated components of the
emission limitation, must meet the
applicable level of control required for
the type of SIP provision (e.g., be RACT
for sources located in nonattainment
areas) and must be legally and
practicably enforceable.’’ 23
Accordingly, here EPA must evaluate
whether this combination of limits
satisfies the OTR RACT requirement.
PADEP did not provide any justification
for why these limits appropriately
function as alternative emission limits.
In the 2015 SSM SIP Action, EPA
recommended states consider seven
criteria when developing alternative
emission limits.24 These recommended
criteria assure the alternative emission
limitations meet basic CAA
requirements. PADEP did not explain
why the alternative emission limitations
included in this SIP revision meet CAA
requirements, including RACT, and EPA
cannot approve alternative emission
limitations without such a showing.
Further, PADEP developed the
emissions limits for the Keystone,
Conemaugh and Homer City Facilities
by reviewing only operating data and
emissions rates from a limited number
of years.25 PADEP claims that using
emissions and operating data from a
limited set of relatively recent years is
justified because these years reflect
what is currently possible due to aging
22 ‘‘State Implementation Plans: Response to
Petition for Rulemaking; Restatement and Update of
EPA’s SSM Policy Applicable to SIPs; Findings of
Substantial Inadequacy; and SIP Calls To Amend
Provisions Applying to Excess Emissions During
Periods of Startup, Shutdown and Malfunction’’ 80
FR 33840, section XI.D.
23 Ibid. P 33913.
24 Ibid. p. 33914.
25 EPA also notes an inconsistency in how PADEP
discusses the data that was considered in
developing the limits at issue in this SIP revision.
In the RTCs, PADEP references data from 2016–
2020. (Key RTC p. 8, Con RTC p. 9, and HC RTC
p. 7). However, in the TEMs, PADEP references data
from 2017–2020.
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equipment and changes in operating
patterns, including the impact of
changes made to the catalyst in the SCR
system in order to meet the
requirements of the 2011 Mercury Air
Toxics Standard (MATS) (Key RTC p. 8,
Con RTC p. 9, and HC RTC p. 7).
However, PADEP presented no data or
analysis showing that aging equipment,
particularly the SCR control systems,
have deteriorated such that data from
earlier years are unreliable. PADEP’s
submittals have also not justified a rate
selection methodology that relies on a
limited set of years, nor have they
explained why the selected years
represent the lowest rate that can now
be achieved when accounting for such
changes. Stated differently, the RACT
limits (regardless of averaging time)
must reflect levels that represent
periods of good emissions control, not
business as usual (e.g., a 5-year average
of past results) or higher-emitting
periods.
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Selection of the SCR-On lb/MMBtu Daily
Average Emission Rates
PADEP’s own data and analysis calls
into question whether the final SCR-on
daily average lb/MMBtu rates for
Conemaugh (0.070 lb/MMBtu),
Keystone (0.080 lb/MMBtu) and Homer
City (0.080 lb/MMBtu for Units 1 and 2,
and 0.070 lb/MMBtu for Unit 3) are
RACT. Based on PADEP’s SIP
submission, EPA cannot determine
whether the SCR-on rates for any of the
three facilities are the lowest rates that
can be achieved considering
technological and economic feasibility.
Although PADEP makes a general
determination that optimization of the
existing SCRs at each facility is RACT,
the data PADEP provided in its SIP
submission do not support a claim that
these rates are the lowest achievable
rates that can reasonably be obtained at
each unit when the SCRs are operating,
considering technological and economic
feasibility. In addition, PADEP then
applies an upward adjustment to these
rates to account for factors, such as lag
time, changes in boiler operating
patterns, and aging of equipment, that
PADEP states it has already accounted
for by using data from 2017 to 2020 in
their analyses for setting the RACT
limits. As such, there should be no
needed upward adjustment to account
for these factors. Also, PADEP
consistently applies a compliance
margin to its rates without explaining
what the margin is, in many cases, or
why such a margin is needed to make
the selected limit technologically or
economically feasible.
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Conemaugh
For Conemaugh, PADEP asserts that it
examined CAMD emissions and other
data for Units 1 and 2 for the years
2017–2020, but because both units are
similar, assumed that data from unit 1
applied to unit 2 and therefore only
discussed unit 1 data.26 Con TEM, pp.
3–4. Figure 1 in the TEM is a graph
showing percentage of heat input, NOX
emission rates and percentage of
ammonia injection rates during May
2017. From this graph, PADEP
determined that Conemaugh Unit 1
maintained a NOX emission rate of
0.045 lb/MMBtu from May 5th through
May 18th, which PADEP attributed to
an ammonia injection control system
operating at a set point of 0.045 lb/
MMBtu. Con TEM, p. 4. From May 19th
through the end of May 2017, PADEP
observed that the ‘‘relative difference
between the ammonia injection rates
and heat input rates have increased,’’
leading to a steady NOX emission rate
around 0.08 lb/MMBtu. Id. PADEP then
notes that following May 2017, unit 1
only operated with varying set points
between 0.065 and 0.08 lb/MMBtu
throughout the 2017 and 2018 ozone
seasons. Con TEM, p. 5. PADEP further
observed that NOX rates increased
significantly in 2019 and provided a
graph (Figure 2) which PADEP asserts
shows that during this month,
Conemaugh ceased injecting ammonia
for NOX control at around 50% heat
input, and even when operating at
100% of heat input, the NOX emission
rates stayed around 0.1 lb/MMBtu.
PADEP concluded that ‘‘this strongly
suggests that additional emission
reductions would be achieved if the
operator operated the SCR with a lower
emission set point while the SCR is
running.’’ Con TEM, p. 6. In addition,
PADEP identified an April 2020
example when the SCR was not
operating despite the boiler operating at
loads ‘‘clearly supporting’’ SCR
operation, with NOX emissions close to
0.3 lb/MMBtu during this time. Con
TEM, p. 7. From this PADEP concluded
that ‘‘[s]imply choosing not to operate
the SCR is not indicative of the control
level achievable by the system.’’ Id.
Based on this data, PADEP then selected
an SCR-on rate of 0.07 lb/MMBtu for
Conemaugh. Id. The only explanation
given for this specific rate is that it
‘‘includes a factor to provide an
appropriate compliance margin,
26 In response to a comment submitted on
Conemaugh, PADEP replied that during the 2018
ozone season, with a few exceptions, Conemaugh’s
unit 2 was consistently able to achieve daily
emission levels in the .055–.07 lb NOX/MMBtu
range. Con. RTC, p. 7.
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fluctuations in load, any lag in the
control system as well as to account for
other factors in the facility’s future
operations.’’ Con TEM, p. 8.
The response to comments (RTC)
document for Conemaugh adds
discussion of a 2017 study performed on
unit 1 in May 2017 that suggested that
running the SCR with a set point of 0.04
lb/MMBtu caused a spike in mercury
emissions, and also discusses a 2016
study at the end of ozone season on unit
2 that suggested running the SCR at a
0.050 lb/MMBtu set point also caused
an increase in mercury emissions. RTC,
pp. 6–8. Based on further analysis,
PADEP concluded that ‘‘a setpoint of
0.06 lb NOX/MMBtu . . . is achievable
by [Conemaugh].’’ RTC p. 8. However,
the RTC states, without explanation,
that PADEP is choosing to keep the 0.07
lb NOX/MMBtu daily average emission
rate. RTC p. 8.
EPA finds that PADEP’s explanation
of why this limit meets the definition of
RACT is inadequate. Having concluded
in the RTC that a 0.06 setpoint is
achievable at Conemaugh, PADEP
provides no explanation as to why it
selected 0.07 lb/MMBtu as the daily
average SCR-on rate. Nor is there any
explanation of why a compliance
margin is necessary, what compliance
margin was applied in this instance,
how fluctuations in load or lag in the
control system affect the lowest
achievable emissions rate, and how or
why the rate must be adjusted to
account for future operations. In the
absence of an explanation of how
PADEP selected the specific 0.07 lb/
MMBtu rate and how any of these other
factors affect the technical and
economic feasibility of the lowest rate
identified, EPA cannot support PADEP’s
conclusion that the 0.07 lb/MMBtu
daily average rate is RACT for when
Conemaugh’s SCRs are operating.
Keystone
Like Conemaugh, PADEP’s analysis
for Keystone’s SCR-on daily average rate
of 0.08 lb/MMBtu does not adequately
explain why this rate represents the
lowest emission limit that Keystone’s
two units are capable of meeting based
on technological and economic
feasibility. In the TEM for Keystone,
PADEP explains that it analyzed EPA’s
CAMD data for Keystone Units 1 and 2
from 2017–2020. Key TEM, p. 3. The
TEM then includes a graph (Figure 1)
showing certain daily operating
statistics for unit 2 for the month of May
2017, from which PADEP concludes
that unit 2 was able to maintain a NOX
emission rate below 0.06 while the SCR
was operating. TEM, p. 4. The TEM then
shows a graph (Figure 2) plotting certain
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daily operating parameters for unit 1
during May 2017. TEM, p. 5. From
Figure 2, PADEP concludes that unit 1
was able to achieve a 0.05 lb/MMBtu
rate for ten days, but this rate increased
to 0.09 lb/MMBtu for the rest of the
month because the operator elected to
inject less ammonia into the SCR system
even though the heat input remained
almost constant at levels supporting
SCR operation. Key TEM, p. 5. From
this and other data, PADEP concludes
that both Keystone units can achieve an
SCR-on rate of 0.06 lb/MMBtu on a
daily average basis.
The Keystone response to comments
contains a long discussion of a study
Keystone submitted at some point in
time purporting to show the effects of
trying to operate the SCRs at a NOx
emission rate setpoint of 0.05 to 0.06 lb/
MMBtu during May 2017. Keystone
RTC, p. 26. The RTC notes that when
Unit 2 attempted to operate at 0.055 lb/
MMBtu for two months in 2017,
pressure drop across the air preheater
increased to a level requiring
measures—in this case raising the SCR
setpoint to 0.08 lb/MMBtu—to reduce
the pressure drop. Id. at 27. The same
study found that operating unit 1’s SCR
at a 0.05 lb/MMBtu setpoint for only 15
days resulted in SCR catalyst fouling
which prevented the SCR from
operating under 0.08 to 0.09 lb/MMBtu
rates for the rest of the test period. Id.
The Keystone RTC then discusses at
length the meaning of the study and
information submitted by another
source and the effect of different SCR set
points on pressure drop, catalyst
fouling, and the ability to meet certain
NOX emission rates. Key RTC, pp. 27–
30. PADEP concluded from these
studies that Keystone should conduct a
future setpoint study to determine that
optimal emission levels from the SCR
are achieved, but that based on the
current evidence, the SCR controls
setpoint should be changed from 0.06 to
0.07 lb NOX/MMBtu.27 Key RTC, p. 32.
However, PADEP set a NOX emission
rate of 0.08 lb/MMBtu because ‘‘varying
load conditions and other factors can
and do affect SCR performance and
resulting NOX emission rates.’’ TEM, p.
6.
EPA acknowledges that catalyst
fouling and other similar factors may
affect the feasibility of SCR to achieve
27 The final unredacted permit does not mention
this setpoint study. Instead, Section E, Source
Group Restrictions, subsection VI, Work Practice
Requirements, condition #012 requires that
Keystone submit a technical evaluation to PADEP
on the possibility of heating the flue gas prior to the
SCR inlet to allow SCR operation at low load levels.
Keystone final permit, p. 172. This condition does
not appear in the redacted final permit submitted
for inclusion into the SIP.
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low rates. However, similar to EPA’s
review of the Conemaugh limit, in the
absence of an explanation of how any of
these other factors affect the technical
and economic feasibility of the lowest
rate identified, EPA cannot support
PADEP’s conclusion that the 0.08 lb/
MMBtu daily average rate represents
RACT.
Homer City
Similar to EPA’s assessment of the
rates for Conemaugh and Keystone,
PADEP does not provide adequate
justification for Homer City’s final SCRon daily average rates of 0.08 lb/MMBtu
for units 1 and 2 and 0.07 lb/MMBtu for
unit 3 are the lowest emission limit that
these sources can meet based on
technological and economic feasibility.
The TEM for Homer City explains that
PADEP evaluated data from 2017–2020
for all three units. PADEP notes that the
unit 1 and 2 SCRs were upgraded in
2018, and ‘‘NOX emission rates
significantly improved,’’ TEM, p. 6, but
fails to explain why, in light of this,
PADEP thought consideration of 2017
data was appropriate. For units 1 and 2,
PADEP notes that during 2019 and 2020
the SCRs were operated to generally
keep NOX emission rates at 0.10 lb/
MMBtu, but also identified periods of
time when the NOX emission rate for
unit 2 went as low as 0.05 lb/MMBtu
because more ammonia was being
injected. TEM, p. 5. The TEM states that
other instances of between 0.05 and 0.10
lb/MMBtu were identified. TEM, p. 5.
Looking at additional data following the
upgrade, PADEP suggested that ‘‘had
July of 2020’s ammonia injection rates
matched that of July 2019, significantly
[sic] emissions reductions could have
been achieved during that timeframe.’’
TEM p. 6. The TEM then states that
‘‘[d]espite the evidence presented,’’
other factors such as load, exhaust
temperature, etc., and other unspecified
factors ‘‘can and do affect SCR
performance’’ and require an operating
limit above the never specified
achievable minimum. TEM, p. 8. PADEP
then selected an SCR-on rate of 0.08 lb/
MMBtu as a daily average for units 1
and 2 but provided no analysis or
explanation why 0.08 lb/MMBtu is the
lowest rate that these units could meet
based on technological and economic
feasibility. See TEM, pp. 4–9. The TEM
also states that the rate includes an
unspecified factor to include a
compliance margin, account for load
fluctuations, control system lags, and
projected future changes in operations.
TEM, p. 9. In the RTC, PADEP seems to
apply the ‘‘findings’’ from Keystone’s
attempt to operate the SCRs with a low
0.05 lb/MMBtu setpoint that such a
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setting leads to fouling of the air
preheater, high pressure drops, and SCR
catalyst fouling before determining that
an emission rate of 0.08 lb/MMBtu will
not cause these problems at Homer City.
RTC, p. 11.
For unit 3, the TEM states that there
is evidence that unit 3 can meet a NOX
emission rate between 0.08 and 0.09 lb/
MMBtu, but limited evidence that it can
meet a lower limit under certain
circumstances. TEM, p.10. Citing the
same factors affecting SCR performance
as it cited for units 1 and 2, PADEP then
concludes a value above the minimum
SCR rate is needed, but without
explanation sets the SCR-on daily
average rate at 0.07 lb/MMBtu. TEM, p.
13. In their response to comments
document, PADEP seems to rely upon
Keystone’s study of operating the SCRs
at a low set point to support their
selection of the SCR-on limits for all the
units. However, there is no discussion
of why the Keystone study can be
applied to Homer City, particularly
given that Homer City seems to use an
economizer bypass to keep the SCRs
operating at lower temperatures than
might be possible at Keystone.
Selection of the All Conditions 30-Day
Rolling Average lb/hr Rate
The PADEP permits allow significant
emissions to be excluded from the daily
lb/MMBtu SCR-on rate under a variety
of conditions, and it is necessary to
evaluate whether the alternative
emissions limits applicable during these
excluded conditions constitute RACT.
Although the PADEP permits contain a
daily lb/MMBtu no-SCR rate, PADEP
suggests that the 30-day rolling average
lb/hr rate is ‘‘the glue’’ that holds the
emissions limits together, and EPA
acknowledges that it is a critical
component to the RACT justification
because it establishes the practical
limitation on the extent to which the
source can operate without SCRs over
an extended period of time.
Accordingly, EPA must evaluate
whether PADEP’s 30-day rolling average
limit satisfies the RACT requirement.
EPA’s assessment is that PADEP fails to
clearly demonstrate that the All
Conditions 30-day rolling average lb/hr
rate necessitates that these facilities
operate their SCRs to achieve the lowest
emission rate that is technologically and
economically feasible, which is required
to meet the definitions of RACT.
PADEP asserts that the 30-day rate
represents RACT because ‘‘[a]t any load
above approximately 30%–40%,
operation without control by the SCR
results in emissions greater than 700
lbs/hr.’’ See, e.g., Con RTC p. 6. This
suggests that the SCR would be
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necessary at higher loads, but it does not
address the question of whether it meets
the RACT requirements when the
facilities could run at 30–40% without
using SCR. The EPA believes that it is
possible that the sources could operate
at low loads while simultaneously
meeting the daily All Conditions lb/
MMBtu rate and the 30-day lb/hr rate,
thereby creating a permissible way to
avoid operating the SCR for long periods
of time. This resembles the 600-degree
temperature SCR ‘‘loophole,’’ which the
Third Circuit was highly critical of, that
allowed facilities to operate just below
the temperature threshold at night when
demand was low and to avoid running
the SCR. Sierra Club, 306. The 30-day
lb/hr all conditions rate does not appear
to resolve this issue.
Furthermore, PADEP’s justification
for the All Conditions 30-day lb/hr rates
leave many specifics about the
justification of the selected rates
unanswered. Each of PADEP’s technical
evaluation memos have similar language
stating ‘‘[PADEP] evaluated and
analyzed mass-based NOX emission rate
in pounds per hour on a 30-day rolling
average basis from EPA’s Clean Air
Markets Division (CAMD) database at all
operating conditions . . . from 2017–
2020.’’ PADEP then presents a set of
graphs for each unit depicting the 30day average rolling NOX emissions (lb/
hr) overlaid with percentage of
maximum heat input (MMBtu). The
time frames explored in these graphs is
summarized in table 2 of this document.
TABLE 2—TIME FRAMES FOR 30-DAY AVERAGE DATA PROVIDED BY PADEP
Location in technical evaluation memo
Facility
pg. 16, figure 6 ........................................
pg. 16, figure 6 ........................................
pg. 14, figure 5 ........................................
pg. 14, figure 5 ........................................
pg 18, Figure 11 ......................................
pg 18, Figure 11 ......................................
pg 18, Figure 11 ......................................
Conemaugh .......................
Conemaugh .......................
Keystone ............................
Keystone ............................
Homer City ........................
Homer City ........................
Homer City ........................
None of these graphs displays data for
the full 2017–2020 timeframe PADEP
evaluated and analyzed. Only the
graphs from Homer City units display
data for more than a single year.
PADEP’s analysis then consists of a
qualitative description of the 30-day lbs/
hr average the units were able to achieve
in the time frames in table 2 of this
document, but lacks data or description
of what 30-day lb/hr all conditions rates
were observed outside of those time
frames. Without additional information
about the 30-day average lb/hr rates
achieved during the four years PADEP
analyzed, EPA cannot determine
whether the lb/hr limit selected for each
unit represent an average of these years
of data, which the Sierra Club court
found problematic, or the lowest
emissions in lb/hr which these sources
achieved in this time frame, considering
technological and economic feasibility.
Unit
Time frame
1
2
1
2
1
2
3
May 2017–September 2017.
May 2017–September 2017.
May 2017–September 2017.
May 2017–September 2017.
January 2019–December 2021.
January 2019–December 2021.
January 2019–September 2020 (approximate).
PADEP may or may not have
reviewed a complete set of data from
2017–2020, but the analysis of this was
not included in the technical evaluation
memos or the response to comment
documents. As such, EPA could not
determine whether or this 30-day all
conditions lb/hr rate ‘‘. . . ensures that
the operator will maximize operating
hours with the SCR and minimize heat
input (and total mass emissions) when
operation of the SCR is technically
infeasible.’’
Additionally, the compliance buffer
added to the 30-day lb/hr all conditions
rate does not appear to be sufficiently
justified. PADEP states in its Technical
Evaluation Memo for Conemaugh
‘‘[e]ach of Conemaugh’s units emits
about 580 lb NOX per hour assuming an
emission level of .070 lb/MMBtu and
100% load. The impact to the
environment should never exceed this
level on a long-term basis.’’ Con TEM p.
15. It would appear PADEP arrived at
this number simply by multiplying the
daily SCR-on (lb/MMBtu) Rate by each
boiler’s rated capacity (MMBtu/hr).
Similar statements were made in the
memos for Keystone and Homer City.
See table 3 of this document, for this
calculation for each boiler at Keystone,
Conemaugh and Homer City. The table
also compares this to the permit limits
contained in PADEP’s 2022 SIP
Submission, as well as a simple
calculation of the percent increase in
those limits (a compliance buffer added
by PADEP). However, no explanation is
given for why compliance buffers of 10–
21% are needed, or why certain units
should receive more than double the
buffer of others.
TABLE 3—COMPLIANCE BUFFERS FOR PADEP’S 30-DAY ALL CONDITIONS lb/hr RATES
Facility
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Conemaugh ..............................................
1
2
1
2
1
2
3
Keystone ..................................................
Homer City ...............................................
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limit daily
SCR-on
(lb/MMBtu)
Rated
capacity
(MMBtu/hr)
Unit
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8,280
8,280
8,717
8,717
6,792
6,792
7,260
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capacity
(lb/hr)
0.070
0.070
0.080
0.080
0.080
0.080
0.070
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580
580
697
697
543
543
508
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30-day avg.
(lb/hr)
700
700
770
770
600
600
560
Compliance
buffer
(%)
21
21
10
10
10
10
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Federal Register / Vol. 89, No. 35 / Wednesday, February 21, 2024 / Proposed Rules
EPA Approval Would Not Be Consistent
With CAA Section 110(l)
found at https://www.epa.gov/lawsregulations/laws-and-executive-orders.
Section 110(l) of the CAA prohibits
the Administrator from approving any
SIP revision ‘‘. . . if the revision would
interfere with any applicable
requirement concerning attainment and
reasonable further progress (as defined
in section 7501 of this title), or any
other applicable requirement of this
chapter.’’ For over 15 years, EPA has
interpreted section 110(l) as permitting
approval of a SIP revision as long as
‘‘emissions in the air are not increased,’’
thereby preserving ‘‘status quo air
quality.’’ Ky. Res. Council, Inc. v. EPA,
467 F.3d 986, 991 (6th Cir. 2006); see
also Indiana v. EPA, 796 F.3d 803, 806
(7th Cir. 2015); Ala. Env’t Council v.
EPA, 711 F.3d 1277, 1292–93 (11th Cir.
2013); Galveston-Houston Ass’n for
Smog Prevention v. EPA, 289 F. App’x
745, 754 (5th Cir. 2008). This turns on
EPA’s interpreting ‘‘interfere’’ as
meaning ‘‘to hinder or make worse.’’ Ky.
Res. Council, 467 F. 3d at 995. The court
in a recent Third Circuit decision
confirmed that a 110(l) analysis is not a
one-size-fits-all provision and the
variables that must be analyzed depend
on the particular interference the SIP
revision poses. Center for Biological
Diversity v. EPA, 75 F.4th 174, 181 (3rd
Cir. 2023). Here, with the information
available to EPA, EPA could not
determine that approval of the SIP
revisions at issue would not result in
interference. Therefore, EPA approval of
these SIP revisions would not be
consistent with section 110(l).
A. Executive Order 12866: Regulatory
Planning and Review and Executive
Order 13563: Improving Regulation and
Regulatory Review
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IV. Proposed Action
EPA’s review of these materials
indicates that Pennsylvania’s May 2016
SIP Submittals for Keystone,
Conemaugh and Homer City Generating
facilities: (1) do not adequately support
Pennsylvania’s justification for the
selection of RACT limits for the large
EGU boilers; (2) lack enforceable
objective clear criteria for determining
when emissions from each EGU are
subject to the SCR-on 24-hour average
limit; and (3) contain unbounded
director’s discretion provisions. For
these, and other reasons described
above, EPA is proposing to disapprove
Pennsylvania’s May 26, 2022 SIP
revisions. EPA is soliciting public
comments on the issues discussed in
this document. These comments will be
considered before taking final action.
V. Statutory and Executive Order
Reviews
Additional information about these
statutes and Executive Orders can be
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17:01 Feb 20, 2024
Jkt 262001
This action is not a ‘‘significant
regulatory action’’ as defined by
Executive Order 12866 and was
therefore not submitted to the Office of
Management and Budget for review.
B. Paperwork Reduction Act (PRA)
This proposed action does not impose
an information collection burden under
the PRA because it does not contain any
information collection activities.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have
a significant economic impact on a
substantial number of small entities
under the RFA. This action merely
proposes to disapprove a SIP
submission as not meeting the CAA.
D. Unfunded Mandates Reform Act
(UMRA)
This action does not contain any
unfunded mandate as described in
UMRA, 2 U.S.C. 1531–1538, and does
not significantly or uniquely affect small
governments. The action imposes no
enforceable duty on any state, local or
tribal governments or the private sector.
E. Executive Order 13132: Federalism
This action does not have federalism
implications. It will not have substantial
direct effects on the states, on the
relationship between the national
government and the states, or on the
distribution of power and
responsibilities among the various
levels of government.
F. Executive Order 13175: Consultation
and Coordination With Indian Tribal
Governments
This action does not have tribal
implications as specified in Executive
Order 13175. This action does not apply
on any Indian reservation land, any
other area where the EPA or an Indian
tribe has demonstrated that a tribe has
jurisdiction, or non-reservation areas of
Indian country. Thus, Executive Order
13175 does not apply to this action.
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
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13031
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 merely proposes to
disapprove a SIP submission as not
meeting the CAA.
H. Executive Order 13211, Actions That
Significantly Affect Energy Supply,
Distribution or Use
This action is not subject to Executive
Order 13211, because it is not a
significant regulatory action under
Executive Order 12866.
I. National Technology Transfer and
Advancement Act
This rulemaking does not involve
technical standards.
J. Executive Order 12898: Federal
Actions To Address Environmental
Justice in Minority Populations and
Low-Income Populations
Executive Order 12898 (Federal
Actions to Address Environmental
Justice in Minority Populations and
Low-Income Populations, 59 FR 7629,
February 16, 1994) directs Federal
agencies to identify and address
‘‘disproportionately high and adverse
human health or environmental effects’’
of their actions on minority populations
and low-income populations to the
greatest extent practicable and
permitted by law. EPA defines
environmental justice (EJ) as ‘‘the fair
treatment and meaningful involvement
of all people regardless of race, color,
national origin, or income with respect
to the development, implementation,
and enforcement of environmental laws,
regulations, and policies.’’ EPA further
defines the term fair treatment to mean
that ‘‘no group of people should bear a
disproportionate burden of
environmental harms and risks,
including those resulting from the
negative environmental consequences of
industrial, governmental, and
commercial operations or programs and
policies.’’
Under the CAA, the Administrator is
required to approve a SIP submission
that complies with the provisions of the
Act and applicable Federal regulations.
42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions, the
EPA’s role is to review state choices,
and approve those choices if they meet
the minimum criteria of the Act.
Accordingly, this proposed action
disapproves state law as meeting
Federal requirements and does not
impose additional requirements beyond
those imposed by state law.
The air agency did not evaluate
environmental justice considerations as
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part of its SIP submittal; the CAA and
applicable implementing regulations
neither prohibit nor require such an
evaluation. EPA did not perform an EJ
analysis and did not consider EJ in this
action. Due to the nature of the action
being taken here, this action is expected
to have a neutral to positive impact on
the air quality of the affected area.
Consideration of EJ is not required as
part of this action, and there is no
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17:01 Feb 20, 2024
Jkt 262001
information in the record inconsistent
with the stated goal of E.O. 12898 of
achieving environmental justice for
people of color, low-income
populations, and Indigenous peoples.
This action merely proposes to
disapprove a SIP submission as not
meeting the CAA.
List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
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reference, Intergovernmental relations,
Nitrogen dioxide, Ozone, Reporting and
recordkeeping requirements, Volatile
organic compounds.
Adam Ortiz,
Regional Administrator, Region III.
[FR Doc. 2024–03528 Filed 2–20–24; 8:45 am]
BILLING CODE 6560–50–P
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Agencies
[Federal Register Volume 89, Number 35 (Wednesday, February 21, 2024)]
[Proposed Rules]
[Pages 13022-13032]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-03528]
[[Page 13022]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R03-OAR-2024-0047; FRL-9920-01-R3]
Air Plan Disapproval; Pennsylvania; Reasonably Available Control
Technology Case-by-Case Permits for Keystone, Conemaugh and Homer City
Generating Facilities for the 1997 and 2008 Ozone National Ambient Air
Quality Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA) is proposing to
disapprove state implementation plan (SIP) revisions submitted by the
Pennsylvania Department of Environmental Protection (PADEP) on behalf
of the Commonwealth of Pennsylvania (Pennsylvania). PADEP submitted SIP
revisions for the Keystone, Conemaugh and Homer City electric
generating facilities on May 26, 2022 to address certain reasonably
available control technique (RACT) requirements for the 1997 and 2008
ozone national ambient air quality standards (NAAQS). EPA is proposing
to disapprove the May 26, 2022 SIP revisions for these facilities as
the SIPs contain problematic provisions and fail to justify the
selection of permit limits as RACT consistent with applicable
requirements and case law. This action is being taken under the Clean
Air Act (CAA).
DATES: Written comments must be received on or before March 22, 2024.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R03-
OAR-2024-0047 at https://www.regulations.gov, or via email to
[email protected]. For comments submitted at Regulations.gov, follow
the online instructions for submitting comments. Once submitted,
comments cannot be edited or removed from Regulations.gov. For either
manner of submission, EPA may publish any comment received to its
public docket. Do not submit electronically any information you
consider to be confidential business information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e. on the web, cloud, or other file sharing
system). For additional submission methods, please contact the person
identified in the FOR FURTHER INFORMATION CONTACT section. For the full
EPA public comment policy, information about CBI or multimedia
submissions, and general guidance on making effective comments, please
visit https://www.epa.gov/dockets/commenting-epa-dockets.
FOR FURTHER INFORMATION CONTACT: Sean Silverman, Planning &
Implementation Branch (3AD30), Air & Radiation Division, U.S.
Environmental Protection Agency, Region III, 1600 John F. Kennedy
Boulevard, Philadelphia, Pennsylvania 19103. The telephone number is
(215) 814-5511. Mr. Silverman can also be reached via electronic mail
at [email protected].
SUPPLEMENTARY INFORMATION:
I. Background
The RACT requirements in CAA section 182(b)(2) apply to all ozone
nonattainment areas classified as Moderate or higher (i.e. Serious,
Severe, or Extreme). Section 184(b)(1)(B) of the CAA also applies RACT
to all areas located within ozone transport regions. The entire
Commonwealth of Pennsylvania is part of the Ozone Transport Region
(OTR) established by section 184 of the CAA and therefore subject
statewide to RACT requirements.
On May 16, 2016, Pennsylvania submitted a SIP revision intended to
satisfy CAA sections 182(b)(2)(C), 182(f), and 184 for the 1997 and
2008 8-hour ozone NAAQS for all major sources of nitrogen oxides
(NOX) and volatile organic compounds (VOCs) in Pennsylvania
not subject to control techniques guidelines (CTGs), with a few
exceptions not relevant to this action. On May 9, 2019, EPA published a
final action fully approving certain provisions and conditionally
approving other portions of Pennsylvania's May 16, 2016, SIP submission
to implement RACT for the 1997 and 2008 Ozone NAAQS (hereafter the
``RACT II rule''). 84 FR 20274 (May 9, 2019). Specifically, EPA's
action fully approved sections 121.1, 129.96, 129.97, and 129.100 of
Title 25 of the Pennsylvania Code (25 Pa. Code) as meeting certain
aspects of major stationary source RACT in CAA sections 172, 182, and
184 for the 1997 and 2008 ozone NAAQS, and conditionally approved 25
Pa. Code sections 129.98 and 129.99 following a commitment provided by
Pennsylvania to submit additional SIP revisions to address the
deficiencies identified by EPA in the May 16, 2016 SIP revision. Id. at
20290.
On August 27, 2020, the Third Circuit held unlawful and vacated
EPA's approval of certain SIP provisions challenged by the Sierra Club.
Sierra Club v. EPA, 972 F.3d 290 (3rd Cir. 2020) (``Sierra Club''). The
case related to EPA's approval of only that portion of the RACT II rule
applicable to coal-fired electricity generating units (EGUs) equipped
with selective catalytic reduction (SCR) for control of NOX.
Specifically at issue was EPA's approval of the presumptive RACT
NOX limit for these EGUs of 0.12 pounds of NOX
per Million British Thermal Units (MMBtu) of heat input (lbs/MMBtu)
when the inlet temperature to the SCR was 600 degrees Fahrenheit or
above, found at 25 Pa. Code 129.97(g)(1)(viii); the application of the
less stringent NOX limits of 25 Pa Code 129.97(g)(1)(vi) to
EGUs with SCR when the inlet temperature to the SCR was below 600
degrees Fahrenheit; and the failure of the RACT II rule at 25 Pa. Code
129.100(d) to specifically require these EGUs to keep temperature data
for the inlet temperature to the SCRs and report that data to PADEP.
The Court explained that, while RACT does not require the lowest
achievable emissions limit, Pennsylvania's adoption of a limit derived
from the average historical NOX emissions of the units at
these EGUs, without more, was insufficient. The record showed that
certain units within Pennsylvania were capable of achieving
significantly lower rates of NOX emissions. The Court found
that EPA did not sufficiently explain why a lower standard was
infeasible. Sierra Club, 972 F.3d at 299-303. Second, the Court held
that Pennsylvania's standard acted as a loophole because it permitted
unlimited operations without the use of SCR controls if exhaust gas
temperature was kept below what the Court considered an arbitrary
temperature threshold of 600 degrees Fahrenheit. Id. at 303-07. Third,
the Court held that Pennsylvania's reporting requirements were not
enforceable. Id. at 307-09.
Consequently, the Court vacated EPA's approval of this portion of
the 2016 SIP and ordered EPA either to approve a revised, compliant SIP
or promulgate a FIP within two years (i.e., by August 27, 2022). Sierra
Club at 309. The Court stated that the new standard--SIP or FIP--``must
be technology forcing, in accord with [EPA's] RACT standard, and lack
the gaping loophole found in the [2016 SIP's] enforcement regime.'' Id.
On August 16, 2022, EPA took final action
[[Page 13023]]
to disapprove the vacated portions of the May 19, 2020 approval. 87 FR
50257. EPA published its proposed FIP on May 25, 2022. 87 FR 31798. EPA
issued a FIP on August 31, 2022. 87 FR 53381.
Following the Court's decision, PADEP required that by April 1,
2021, each source within a facility which had been subject to the
presumptive 0.12 lb/MMBtu limit submit a permit application in
accordance with 25 Pa. Code 129.99 setting forth a RACT analysis for
each unit at the facility.\1\ On or about April 1, 2021, Conemaugh,
Homer City, Keystone, and Montour submitted permit applications to
PADEP with RACT analyses.\2\ PADEP found the permit applications to be
technically deficient and therefore issued technical deficiency letters
to each of these sources seeking additional information. Although the
sources submitted additional information, PADEP decided that it would
do its own case-by-case RACT analysis for each EGU at each facility and
propose new RACT limits for each EGU in amended title V permits. Once
these permits became final, PADEP intended to submit each permit to EPA
as a SIP revision to meet the RACT requirement for each source. EPA
also continued to regularly discuss with PADEP their efforts to develop
case-by-case RACT/title V permits for these sources.
---------------------------------------------------------------------------
\1\ See ``Conemaugh RACT II Review Memo'' p. 2, ``Homer City
RACT II Review Memo'' p. 3 and ``Keystone RACT II Review Memo'' p.
2, available in the docket of this action.
\2\ The Bruce Mansfield EGUs ceased all operations prior to
April 1, 2021 and therefore did not submit a RACT permit
application.
---------------------------------------------------------------------------
From September 11, 2021, through November 6, 2021, PADEP serially
issued draft RACT/title V permits for four sources, while Allegheny
County issued a draft RACT/title V permit for Cheswick in December
2021.\3\ EPA submitted timely comments on each draft permit. Many of
the concerns and issues identified in EPA's first set of comments
(which was on the Keystone permit) appeared again in the draft permits
for the other sources. EPA's comments raised significant concerns over
the approvability of each permit because each remained inconsistent
with the court's decision, and PADEP did not address those concerns
with each subsequent draft permit it published for comment. On May 26,
2022, PADEP submitted case-by-case RACT determinations to EPA as a
revision to the Pennsylvania SIP which still contained the
approvability issues EPA had flagged in its comments, for Keystone,
Conemaugh, and Homer City. PADEP submitted a case-by-case RACT
determination for Montour as a revision to the Pennsylvania SIP on June
9, 2022, but subsequently formally withdrew it.\4\ In addition, the
Cheswick facility permanently ceased operations and surrendered all of
its air permits to the Allegheny County Health Department.\5\ The Homer
City facility also ceased all coal-burning operations on July 1,
2023.\6\ Prior to July 1st, only Unit 3 at Homer City was operating.
However, because Homer City has not formally surrendered its CAA
permits, which would demonstrate that the shutdown is permanent, and
because PADEP has not withdrawn the SIP submission with regard to Homer
City, EPA will continue to consider the approvability of the RACT
NOX limits for Homer City.
---------------------------------------------------------------------------
\3\ 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).
\4\ See document dated October 26, 2022 from EPA Region III to
Acting Secretary Ramez Ziadeh of PADEP available in the docket of
this action.
\5\ See document dated April 15, 2022 from Allegheny County to
Lee Bahl of GenOn Holdings LLC available in the docket of this
action.
\6\ See https://www.pjm.com/planning/service-requests/gen-deactivations.
---------------------------------------------------------------------------
EPA notes that the May 2022 permits for Keystone and Conemaugh also
contain case-by-case RACT limits for certain gas or oil-fired auxiliary
boilers at these facilities. However, EPA is not taking action at this
time on the case-by-case RACT limits in these permits for two auxiliary
boilers at Keystone (Source IDs 037 and 038) and the two at Conemaugh
(Source IDs 039 and 041). These auxiliary boilers were not subject to
the presumptive RACT limit in 25 Pa. Code 129.97(g)(1)(viii) for which
EPA issued a final disapproval in August 2022.
II. Summary of the Case-by-Case Permit SIP Revisions
EPA notes that the RACT limits in PADEP's May 2022 SIP submittal
addressed RACT limits for the large Electric Generating Units (EGUs) at
Conemaugh, Keystone, and Homer City for only the 1997 and 2008 ozone
NAAQS. These source-specific limits were established pursuant to 25 Pa.
Code 129.99, which was conditionally approved by EPA in March 2019.
Section 129.99 of 25 Pa. Code allows a source to apply for an
alternative RACT limit (a.k.a. ``case-by-case'' RACT limit) to the
otherwise default (a.k.a. ``presumptive'') RACT limits where
appropriate. In response to comments,\7\ PADEP affirmed that the RACT
limits for the EGUs at these three sources do not address the 2015
ozone NAAQS.\8\
---------------------------------------------------------------------------
\7\ All three Response to Comments (RTC) documents are in the
docket for this matter. The Conemaugh Response to Comments (Con RTC)
and Keystone Response to Comments (Key RTC) are both dated May 12,
2022. The Homer City Response to Comments (HC RTC) in the official
SIP submission is marked ``Draft'' and does not contain a date.
\8\ See, e.g., Conemaugh Response to Comments, p. 2:
``incorporates the provisions and requirements contained in the
amended RACT II approval for the facility, which are intended to
satisfy the [CAA] RACT requirements for the 1997 and 2008 . . .
ozone [NAAQS].''
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Summary of Pennsylvania's Process for Setting Limits
PADEP developed the NOX limits for each of the EGUs at
each facility using a similar methodology, which included using similar
years of data. Table 1 in this document summarizes the three
NOX emission rates applicable to each unit at each facility
as proposed by Pennsylvania for public comment, and the final limits in
the permits submitted by PADEP for approval as SIP revisions.
Table 1--Proposed Rates and Final Rates in 2022 PA SIP Submission
--------------------------------------------------------------------------------------------------------------------------------------------------------
Proposed limits Submitted as SIP revision (final)
-----------------------------------------------------------------------------------------------
Facility Unit Capacity SCR on lb/ All conditions All conditions SCR on lb/ All conditions All conditions
MMBtu daily lb/MMBtu daily lb/hr 30-day MMBtu daily lb/MMBtu daily lb/hr 30-day
avg. avg. avg. avg. avg. avg.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Conemaugh..................... 1....... 8,280 0.070 0.27 700 0.070 0.27 700
2....... 8,280 0.070 0.27 700 0.070 0.27 700
Keystone...................... 1....... 8,717 0.080 0.30 800 0.080 0.30 770
2....... 8,717 0.080 0.30 800 0.080 0.30 770
Homer City.................... 1....... 6,792 0.080 0.45 550 0.080 0.45 600
2....... 6,792 0.080 0.45 550 0.080 0.45 600
3....... 7,260 0.070 0.27 510 0.070 0.27 560
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 13024]]
A technical evaluation memo (TEM) accompanying each draft permit
issued for public comment provided an initial explanation for PADEP's
methodology for determining the proposed RACT level of controls for
each facility.\9\ For each unit at each facility, PADEP states that it
followed a ``top-down'' approach to determine NOX emissions
limits, which included searching for and identifying the ``best
methodology, technique, technology, or other means for reducing
NOX while factoring environmental, energy and economic
considerations into the analysis.'' Con TEM, p. 2; Key TEM, p. 2; HC
TEM, p. 2. This included identifying the controls installed on coal-
fired units in some other states. PADEP then used the EPA Control Cost
Manual (sixth edition), June 12, 2019, and sometimes vendor's quotes,
to determine whether control options PADEP identified as technically
feasible were also cost effective. Con TEM, pp. 2-3; Key TEM, p. 2; HC
TEM, p. 3. PADEP performed some type of analysis for multiple
NOX control technologies \10\ for each facility before
``determin[ing] that no additional controls are cost effective.'' Con
TEM at 3. See, e.g., Con TEM pp. 3-19. In lieu of new controls, PADEP
determined that for each of the three facilities, changes to the way
the facilities operated their SCRs and changes to how they ``tuned''
the boilers were the only technically available and cost-effective
controls for reducing NOX emissions. Con TEM, pp. 2-3; Key
TEM, pp. 2-3; HC TEM, pp. 2-3. This approach resulted in PADEP adopting
three separate but related limits for each EGU at each of the three
facilities. The proposed and final rates are in Table 1 of this
document. The method that PADEP used to arrive at each of the three
rates is summarized below.
---------------------------------------------------------------------------
\9\ All three technical evaluation memos (TEMs) are in the
docket for this matter. The Homer City technical evaluation memo (HC
TEM) is dated October 14, 2021. The Conemaugh technical evaluation
memo (Con TEM) is dated September 28, 2021. The Keystone technical
evaluation memo (Key TEM) is dated August 25, 2021.
\10\ Potential controls evaluated included: Precombustion
Controls (Switching to Natural Gas, Switching from high to low
emitting or zero emitting units), Combustion Controls (Partial or
full oxy firing, Oxygen enhanced combustion, LNB installation, LNB
Optimization, LNB Upgrade, Flue Gas Recirculation (FGR), Separated
overfired air, Rotating opposed fire air) Post Combustion Controls
(Additional SCR, SCR Optimization, Economizer Bypass during low
load, startup, and shutdown to allow SCR operation, V-temp
economizer during low load, startup, and shutdown to allow SCR
operation, Flue gas reheat during low load, startup, and shutdown to
allow SCR operation, Dry sorbent injection prior to SCR during low
load conditions to allow SCR operation, addition of Selective Non-
Catalytic Reduction (SNCR), SNCR Optimization, Return of partially
operating SCR and SNCR systems to full operation) Station Wide
Improvements (Installation/improvement of digital process controls
on equipment to minimize NOX emissions and detect
equipment in need to maintenance, Improved/increased equipment
cleaning and maintenance practices). See Con TEM p. 4-19; Key TEM,
pp 3-17; HC TEM pp. 3-21.
---------------------------------------------------------------------------
Selection of SCR-on lb/MMBtu Daily Average Rates
To determine the ``SCR-on'' limit representing RACT for when the
SCRs are operating, PADEP ``analyzed daily NOX emissions
rates from EPA's Clean Air Markets Division (CAMD) database at varying
operating load conditions'' for most of the units at each facility. Con
TEM, p. 3; HC TEM pp. 4-13; Key TEM p. 3. PADEP examined data for each
facility ranging from 2016 to 2020, depending on the facility.\11\ For
certain months within the 2016-2020 time frame, PADEP states that it
analyzed the percentage of daily heat input and corresponding
percentage of daily reagent injection for a unit or units at each
facility to ascertain how heat input and reagent input affected daily
NOX emissions, and to determine the lowest emission limit
each unit could technically and economically achieve with the SCRs.
PADEP's analysis included examining the percentage of maximum heat rate
input for the unit for each day of certain months and the corresponding
percentage of maximum ammonia (the reagent used) input observed per day
for the same month. Con TEM, p. 4; Key TEM, pp. 3-8; HC TEM pp. 4-13.
From this data, PADEP identified a ``load'' or heat input level at
which it seemed that Conemaugh stopped injecting ammonia into the flue
gas stream, see Con. TEM, p. 6, but did not identify loads or heat
inputs at which Homer City's or Keystone's units stopped injecting
ammonia. See HC TEM pp. 4-13, Key TEM pp. 3-8. PADEP also presented
NOX emission rate data for certain months for each source
during various ozone seasons, and for some periods outside of ozone
seasons.\12\ For each facility, PADEP found that the automated controls
that run the SCRs seemed to be set at an emissions ``set point,''
expressed as pounds of NOX per million Btus of heat input
(lb NOX/MMBtu), and that these set points varied over
time.\13\ For Conemaugh, PADEP concluded that ``additional emission
reductions would be achieved if the operator operated the SCR with a
lower emissions setpoint while the SCR is running.'' Con. TEM, p. 6.
For Keystone, PADEP stated ``[b]oth units at Keystone seem to be able
to achieve a NOX rate of 0.060 lb/MMBtu on a daily average
basis,'' but cited ``varying load conditions and other factors'' as
affecting SCR performance and therefore proposed (and finalized) a
daily average SCR-on rate of 0.08 lb/MMBtu for both. Key TEM, p. 6.
PADEP does not provide further information on what these other factors
are or what impact they and load conditions would have that lead to the
selection of the 0.08 lb/MMBtu limit. For Homer City units 1 and 2,
PADEP's analysis concluded that the facility seemed to be targeting a
NOX emission rate of 0.10 lb/MMBtu when the SCRs were
operating, but identified ``rare'' periods where the units achieved
rates below 0.05 lb/MMBtu. HC TEM, p. 5. However, PADEP concluded that
``[d]espite the fact that emissions under 0.10 lb/MMBtu are possible
under at least some operating conditions, accounting for other
operating condition requires a limit above the minimum achievable.'' HC
TEM, p. 8. PADEP therefore proposed (and finalized) a 0.080 lb/MMBtu
daily average operating rate for Units 1 and 2 when the SCR is
operating. For Unit 3, PADEP found that it was also targeting a
NOX emission rate of 0.10 lb/MMBtu, but during July 2019 was
able to consistently achieve NOX rates between 0.08 and 0.09
lb/MMBtu despite daily load swings. HC TEM, p. 9-10. PADEP identified
two other instances where Unit 3 was capable of achieving
NOX rates lower than 0.08, but did not identify the lowest
achievable SCR-on rate before determining that other factors require a
limit above the lowest achievable NOX rate.\14\ Without
identifying the lowest achievable NOX emission rate or
explaining how the other factors affect that rate, PADEP proposed (and
finalized) a rate of 0.07 lb/MMBtu when the SCR is operating. HC TEM,
pp. 12-13.
---------------------------------------------------------------------------
\11\ Note that Key TEM p. 3, Con TEM p. 3 and HC TEM p. 4, state
that the years reviewed are 2017-2020, but Key RTC p. 8, Con RTC p.
9 and HC RTC p. 7 state years reviewed were 2016-2020.
\12\ For Keystone, the months examined were May 2017 and April
2018. Key TEM pp. 3-6. For Homer City, the months were June 2019
(unit 1), July of 2019 and 2020 (unit 2), and December 2017, July
2019, September 16, 2019 and Dec. 4, 2019 (unit 3). HC TEM, pp. 4-
14. For Conemaugh, dates examined included May 2017, September 5,
2019, and April 4, 2020. Con TEM pp. 3-8.
\13\ Con TEM, pp. 3-8; Key TEM, pp. 3-7; HC TEM, pp. 4-13.
\14\ The other factors PADEP cites are varying loads, operating
load, catalyst condition, exhaust temperature and velocity, moisture
level, initial NOX levels in the exhaust, and other
unnamed factors. HC TEM, p. 13.
---------------------------------------------------------------------------
Certain changes made to PADEP's proposed rates for each source in
response to comments received are discussed in EPA's analysis of the
final rates.
[[Page 13025]]
Selection of All Conditions lb/MMBtu Daily Average Rate
The lb/MMBtu limits in the ``All Conditions lb/MMBtu Daily
Average'' columns of Table 1 in this document, represent the daily
average NOX limits that PADEP determined each unit at each
facility could achieve solely through the operation of its existing
low-NOX burners with overfire air, so long as the sources
``tuned'' their boilers to optimize the reduction of NOX
rather than to obtain the highest heat output. PADEP describes boiler
tuning as making a number of adjustments to the boiler operating
parameters that affect the generation of NOX in the boiler
fire box, including excess air levels, secondary air biasing, fuel/
auxiliary air damper adjustments, burner tilt, fuel flow biasing, and
changes to primary air flows. See, e.g., Con. TEM, pp. 14-15. As stated
in the technical evaluation memo for Conemaugh, ``[g]enerally boiler's
regular inspection, preventive maintenance, tuning, practicing during
shutdown and upset conditions to prevent excess emissions, inspections
and testing of Over Fire Air (OFA) components, and adjusted of burner
angle to minimize NOX emissions results in lowering
NOX emissions by 5-15% or at an average of 10. %. [sic]''
Con. TEM, p. 15. For each of the EGU boilers (units) at each of the
facilities, PADEP determined that the boiler burners had not been tuned
to minimize NOX emissions, but rather had been tuned to
maximize output. Key TEM, p. 13; HC TEM, p. 15; Con TEM, pp. 14-15. For
each facility, PADEP concluded that tuning the boilers to minimize
NOX emissions could result in lowering NOX
emissions by 5% to 15%, so PADEP elected to apply an average
NOX reduction of 10% when setting the ``All Conditions lb/
MMBtu Daily Average'' rate. Id.
Selection of All Conditions 30-Day Rolling Average lb/hr Rate
Regarding the 30-day rolling average pounds of NOX/hour
limits in the column in Table 1 labeled ``All Conditions lb/hr 30-day
Average,'' there is some ambiguity in how PADEP arrived at the final
rates for Keystone and Conemaugh. In the Keystone RTC, PADEP states the
30-day lb/hr limit was ``derived from the emission level at 0.08 lb/
MMBTU at full load . . . with an additional small margin to account for
the fact that it is impossible to completely avoid all periods of
operation when complying with the 0.080 lb/MMBtu is technically
infeasible.'' Key RTC, p. 10. Similar language stating that the 30-day
lb/hr rate was derived from the daily SCR-on rates is also in Con RTC
p. 11 and HC RTC p. 9. PADEP's explanation for how the 30-day lb/hr
limits were derived in the Technical Evaluation Memos is more ambiguous
and does not explicitly state the 30-day lb/hr rate is derived from the
daily SCR-on lb/MMBtu rate. A description of what PADEP did in the
Technical Evaluation Memos is outlined below.
PADEP seems to have generally performed a similar analysis of
similar years of data for all three facilities, but used a different
method to set the 30-day lb/hr rates for Conemaugh and Homer City than
for Keystone. For each source at each facility, PADEP says it analyzed
``mass-based NOX emission rate in pounds per hour on a 30
operational day rolling average basis using EPA's CAMD database at all
operating conditions for [the units] from 2017-2020. Mass based
emission rate on a 30 operational day rolling average basis is
dependent on number of hours a unit is operated, on average, at high
load vs low load for the past 30-days [sic].'' \15\ Con TEM p. 15; see
also Key TEM pp. 13-14, HC TEM pp. 17-19.
---------------------------------------------------------------------------
\15\ The Conemaugh TEM does not show the results of the full
analysis of the 2017-2020 data. For example, Figure 6 in the Con TEM
shows only ozone season operating load versus 30-day rolling average
NOX emissions on a lb/hr basis for the 2017 ozone season.
Con TEM, p. 6.
---------------------------------------------------------------------------
Following this analysis for each facility, for Conemaugh and Homer
City PADEP used the SCR-on lb/MMBtu rate for each unit at each
facility, then multiplied that SCR-on rate by each unit's maximum MMBtu
per hour rating to arrive at the number of pounds per hour that each
unit would emit if they ran at their full heat input rating while
complying with that unit's SCR-on lb/MMBtu rate. For example, the
technical review memo for Conemaugh explains that:
``Each of Conemaugh's units emits about 580 lb NOX
per hour assuming an emission level of .070 lb/MMBtu and 100% load.
The impact to the environment should never exceed this level on a
long-term basis. The Department is proposing a limit of 700 lb/hr
limit on a 30 operational day rolling basis which accounts for all
operating scenarios including situations during which the SCR is not
able to operate. The compliance buffer also accounts for the fact
that both units at Conemaugh operate as much as 10% over their rated
capacity.'' (Con TEM, p.15).
For Conemaugh, PADEP concluded that Units 1 and 2 were operating
between 55% and 100% load during this time and both were able to
achieve at or below 625 lb/hr on a 30-operating day basis. PADEP found
that during this time period both units operated at around a 0.075 lb/
MMBtu NOX emissions rate, with occasional higher spikes in
rate. Based on this data, PADEP concluded:
``Given that the Department believes that NOX rates
below .07 are readily achievable with the SCR in operation, and the
fact that both units were able to achieve a 30-day rolling
NOX rate of under 625 lb/hr despite operating at a rate
between .075 and .1, DEP believes that Conemaugh Generating Station
can achieve a NOX rate of 700 lb/hr on a 30-day rolling
basis. Even if the facility were to operate at low load for a
significant time during a 30-day averaging period--generating
significantly more mass emissions than operation at higher loads
with SCR, emission rates at high load should be significantly below
700 lb/hr allowing the facility to ``make up'' for higher emissions
during times of low load, assuming the facility operates to the
NOX rate of .045-.05 lb/MMBtu it is usually capable of
meeting when the SCR is operating.'' Con TEM, pp. 16-17.
Thus, for Conemaugh, PADEP proposed and finalized an all conditions 30-
day rolling average lb/hr limit of 700 lb/hr.
For Homer City, PADEP used the proposed SCR-on daily average
NOX limit of 0.08 lb/MMBtu for Units 1 and 2, multiplied by
the maximum MMBtu per hour for each of these units, to arrive at a 30-
day rolling average limit of 550 lb of NOX per hour for each
unit. For Unit 3, PADEP used the proposed SCR-on lb/hr daily average
limit of 0.07 lb/MMBtu multiplied by the maximum heat input for Unit 3
to arrive at a rolling 30-day average limit of 510 lbs of
NOX per hour. HC TEM, p. 17. In response to a comment from
Homer City, PADEP raised the 30-day rolling average lb/hr limits to 600
lb/hr for Units 1 and 2 and 560 lb/hr for unit 3.
For Keystone, PADEP appears to have arrived at its proposed and
final 30-day rolling average lb/hr limit through a different method.
PADEP's TEM states that PADEP analyzed the mass-based NOX
emission rate pounds per hour on a 30-day rolling average at all
operating conditions for Units 1 and 2 from 2017-2020. Key TEM, p. 13.
The TEM then provides Figure 5, which graphs the 30-day rolling
NOX rates for Units 1 and 2, but only for the 2017 ozone
season. Key TEM. P. 14. From Figure 5, the TEM concludes that both
units were able to achieve at or below 800 lbs/hr on a 30-day rolling
average basis, continuously. Key TEM, p.14. The TEM then asserts that
based on the CAMD data, ``DEP believes that by managing combination of
hours of operations when a unit is operating at loads supporting SCR
and at lower loads with [low NOX burners], Unit 1 and Unit 2
can achieve 800 lbs/hr on a 30-day operating day rolling average basis
despite the changes in utilization of the boiler.'' Id. From this,
[[Page 13026]]
PADEP concluded that the 800 lb/hr 30-day rolling average limit under
all operating conditions is RACT. Id. However, in response to comments,
this limit was changed to 770 lbs/hr for both units. Key RTC pp. 6.
In the response to comments document for Conemaugh, PADEP explained
that the 30-day rolling average lbs/hr all conditions rate ``. . . is
the glue that holds the three emission limits together and ensures that
the emission reductions from the two Conemaugh Generating Station units
are maximized . . . This emission limit applies at all times and in all
circumstances, without exception.'' Con RTC, p. 6.\16\ PADEP further
asserts that the SCR-on lb/MMBtu daily average rate minimizes the
emissions that occur when operating with the SCR, while also claiming
that the 30-day rolling average lb/hr all conditions rate minimizes
``both the amount of time that the units can be operated when the SCR
is technically unavailable, as well as forces the load (and therefore
mass emission rate) to the lowest rate possible when it is not being
operated due to technical unavailability.'' See, e.g. Con RTC, p. 6.
The RTC further explains that ``[a]t any load above approximately 30%-
40%, operation without control by the SCR results in emissions greater
than 700 lbs/hr. As the load climbs, the emissions per hour climb
proportionately.'' Id. PADEP asserts that the 700 lb/hr rolling 30-day
average limit ``ensures that the operator will maximize operating hours
with the SCR and minimize heat input (and total mass emissions) when
operation of the SCR is technically infeasible.'' Id.
---------------------------------------------------------------------------
\16\ Nearly identical statements are in Key RTC p. 6 and HC RTC
p. 6.
---------------------------------------------------------------------------
III. EPA's Evaluation of the RACT Permit Limits in the SIP Submittals
EPA's review of the RACT permit limits in each of the three case-
by-case RACT permits submitted as SIP revisions by PADEP has identified
several issues appearing in each permit which preclude approval of the
SIP submissions as satisfying RACT requirements. In summary, EPA has
determined that there are issues regarding the enforceability of the
SCR-on permit limits, Director's discretion issues related to the SCR-
on limits, and an inadequate justification for why the SCR-on limits
meet the definition of RACT for each source. Moreover, because some of
the 30-day rolling hourly average pound per hour mass limits appear to
be derived from the daily lb/MMBtu SCR-on limits, the failure of the
SCR-on limit to meet the criteria for RACT calls into question whether
the 30-day limits are RACT.\17\ Also, EPA cannot verify from PADEP's
submitted SIPs whether these 30-day rolling average pound per hour mass
limits actually act as a constraint on operation of the EGUs without
operation of the SCRs in a way that represents RACT. In addition, PADEP
has added a ``compliance margin'' buffer to the 30-day rolling average
pound per hour limits without an adequate explanation of why that
buffer is necessary to make the limits technologically or economically
feasible. Each of these issues is discussed below. As a result, EPA is
proposing to disapprove this SIP revision.
---------------------------------------------------------------------------
\17\ In Key RTC p. 10 PADEP states the 30-day lb/hr limit was
``derived from the emission level at 0.08 lb/MMBTU at full load . .
. with an additional small margin . . .'' Similar language stating
that the 30-day lb/hr rate was derived from the daily SCR-on rates
is also in Con RTC p. 11 and HC RTC p. 9. PADEP's explanation for
how the 30-day lb/hr limits were derived in Key TEM pp. 13-14, Con
TEMP pp. 15-17 and HC TEM pp. 17-19 is more ambiguous and doesn't
explicitly state the 30-day lb/hr rate is derived from the daily
SCR-on lb/MMBtu rate as noted under the ``Selection of All
Conditions 30-day Rolling Average lbs/hr Rate'' heading in section
II.
---------------------------------------------------------------------------
Lack of Enforceability of the ``SCR-On'' Limits for Each EGU at Each
Facility
Neither the permits nor the background information submitted with
the SIP set forth clear, objective criteria for determining when
emissions from each EGU are subject to the SCR-on lb/MMBtu daily
average limit(s). As such, it is not possible in all circumstances for
EPA or the public to determine whether this limit applies, and
therefore whether the sources are in noncompliance with that limit. As
a result, EPA is proposing to disapprove the PADEP SIP revision on this
basis.
Each permit includes language stating the NOX emissions
are limited at a certain level, but that certain emissions are excluded
when evaluating whether the limitations are met. Specifically, the
permits contain exclusions for:
``. . . emissions during start-up, and shut-down; operation pursuant
to emergency generation required by PJM, including any necessary
testing for such emergency operations; and during periods in which
compliance with this emission limit would require operation of any
equipment in a manner inconsistent with technological limitations,
good engineering and maintenance practices, and/or good air
pollution control practices for minimizing emissions.'' See, e.g.,
Conemaugh final permit, Section E, Restrictions, #001, p. 176.
Keystone Final Permit, p. 169, and Homer City Final Permit p.
134.\18\
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\18\ PJM is the Pennsylvania-New Jersey-Maryland
Interconnection, a regional transmission organization operating in
the midatlantic states.
EPA has determined that the exclusion during ``Operation pursuant
to emergency generation required by PJM'' is problematic. This
condition is not defined in the permit for Homer City but is defined in
the final permits for Conemaugh (p. 176) and Keystone (p.169), stating
that ``the emissions limit remains in effect unless the permittee
demonstrates that compliance with the [applicable emission limitation]
is technically infeasible.'' There are no bounds or explanation in the
permit regarding what would equate to technical infeasibility, nor is
there information on whom the permittee would demonstrate this
infeasibility to or how EPA or the public could determine whether such
an adequate demonstration was made. In response to comments, PADEP
---------------------------------------------------------------------------
stated:
``the Conemaugh Station permit includes a process where emissions
can be requested for exclusion from calculation of the 0.070 lb/
MMBtu emission limit if the owner/operator makes a demonstration of
technical infeasibility to the Department's satisfaction. The
general factors that may lead to technical infeasibility are
included in the Conemaugh Station permit, and mirror SIP-approved
RACT regulations in neighboring states. In fact, the list of general
factors in Conemaugh's permit is more limited than the factors
listed in regulations promulgated by one commentator. See COMAR
26.11.38.04 section 4.'' \19\ Con RTC, p. 3.
---------------------------------------------------------------------------
\19\ COMAR is the Code of Maryland Regulations.
EPA did not find the suggested list of ``general factors'' which may
lead to a determination of technical infeasibility.
EPA also notes that this type of post-hoc determination allowing
the director to grant exemptions from a SIP-approved emission limit
during periods of startup, shutdown or other periods is the type of
director's discretion prohibited by the CAA, for the reasons set forth
in EPA's 2015 startup, shutdown and malfunction (SSM) SIP Action. 80 FR
at 33840, 33917 (June 12, 2015). As stated in the 2015 SSM SIP Action,
``SIP provisions cannot contain director's discretion to alter SIP
requirements, including those that allow for variances or outright
exemptions for emissions during SSM events.'' 80 FR at 33917. In the
case of the permits submitted as part of Pennsylvania's 2022 SIP
revision, each contains language that allows the director to decide
whether or not emissions from a source during any hour should be
counted towards the more stringent SCR-on emission limits of 0.07-0.08
lb/MMBTU or to the less stringent emission limits of 0.27-0.45 lb/
MMBTU. Although the rates would not change, the director would be
making a
[[Page 13027]]
decision as to whether certain emissions should be exempted from the
more stringent SCR-on lb/MMBtu 24-hour average rate. This is the type
of unilateral, ad hoc (or post hoc) decision by the director which
could negate the possibility of enforcement of an otherwise enforceable
SIP emission limit by EPA or the public and which is barred by EPA as
first established in the 1999 SSM Guidance. 1999 SSM SIP guidance at 3,
80 FR 33840 at 33917.
In addition, pursuant to EPA's responsibilities under sections
110(k)(3), 110(l) and 193 of the CAA, the Agency cannot approve a SIP
provision that automatically preauthorizes the state to unilaterally
revise the SIP emission limit (in this case by making determinations
that it did not apply at certain times) without meeting the applicable
procedural and substantive statutory requirements for SIP revisions. 80
FR at 33918. As stated in EPA's 2015 SSM SIP Action, ``[i]t is a
fundamental tenet of the CAA that states cannot unilaterally change SIP
provisions, including the emission limitations within SIP provisions,
without the EPA's approval of the change through the appropriate
process.'' Id.
In the quoted response to comments on this issue, PADEP claims that
the list of general factors in the permits (which EPA could not locate)
are more limited than factors listed in Maryland's regulations. EPA
notes that it has not approved the cited Maryland regulation, COMAR
26.11.38.04, as RACT for EGUs, so the cited example does not carry any
weight in EPA's analysis of this SIP revision.\20\ PADEP claims that
the list of general factors (which again, EPA could not locate)
``mirror SIP-approved RACT regulations in neighboring states,'' but
PADEP does not identify these other SIP-approved RACT regulations and
EPA is not aware of what PADEP may be referencing. Without knowing
which SIP-approved RACT regulations PADEP is referring to, EPA cannot
judge the relevance of this argument.
---------------------------------------------------------------------------
\20\ See the final document at 82 FR 24546 (May 30, 2017)
approving the NOX limits for Maryland's EGUs as SIP
strengthening measures, and the final document at 84 FR 5004
(February 20, 2019) approving Maryland's RACT regulations for
controlling VOC major sources for the 2008 ozone NAAQS, which notes
that Maryland will address major sources of NOX in
another SIP. None of the VOC regulations approved included the
language in COMAR 26.11.38.04.
---------------------------------------------------------------------------
The exclusion for ``periods in which compliance with this emission
limit would require operation of any equipment in a manner inconsistent
with technological limitations, good engineering practices, and/or good
air pollution control practices . . .'' is also problematic. No permit
provides additional definitions or instruction on how this provision
should be interpreted or applied. Similar to other provisions at issue
here, this lack of definition makes this exemption provision difficult
or impossible to enforce.
Although the permits require that the sources keep certain data and
submit a monthly report to PADEP, it is in the sources' discretion to
identify in these monthly reports ``whether or not they believe they
are subject to the [SCR-on] lb NOX/MMBtu limit'' and
``clearly document how [they] determined whether or not they believe
they are subject to the [SCR-on] lb NOX/MMBtu hourly
limit.'' \21\ But this does not explain how PADEP will determine
whether certain hours of NOX emissions from the sources
should be counted towards the SCR-on daily average lb/MMBtu limits for
each source, or the circumstances under which these emissions would be
excluded from the limit. It is even more difficult to understand how
EPA or the public would discern which hours of emissions should be
counted towards the SCR-on limit. If it is unknown which hours of
emissions count, it is impossible to determine whether a source
complied with the SCR-on limit. In other words, without clear and
objective criteria for excluding these emissions, neither EPA nor the
public could determine whether the sources were complying with the SCR-
on limit at each source. Although this situation is somewhat different
than the situation faced by the Third Circuit in the Sierra Club appeal
(lack of adequate recordkeeping), the lack of objective criteria for
determining compliance in this situation leads to the same problem
identified by that court, which is that there is no way for interested
members of the public or EPA to conduct oversight. Sierra Club at 307.
---------------------------------------------------------------------------
\21\ Conemaugh final permit, p. 177. The final unredacted
permits for all three facilities also state that the monthly reports
should include the hourly load levels, heat input, ammonia injection
rates, NOX rates, total NOX emissions, the SCR
emission set point, SCR inlet and outlet temperature, and clearly
indicate any days which the SCR-on lb/MMBtu emission limit is
exceeded. For days exceeding the SCR-on lb/MMBtu limit, the above
information must be provided on an hourly basis and the permittee
must give a detailed explanation for why they exceeded their
emission limit. Conemaugh permit, p. 176, Keystone permit pp. 170-
171, Homer City permit p. 137.
---------------------------------------------------------------------------
Pennsylvania's Inadequate Justification of Certain Limits as RACT
EPA understands the PADEP's submission to argue that RACT for these
facilities is comprised of: (1) a low daily SCR-on lb/MMBtu limit with
exclusions as outlined in the prior section; (2) a much higher all
conditions daily lb/MMBtu limit that provides a permissible emissions
level under all operating conditions including when the SCR is not
operating; and (3) the 30-day rolling average all conditions lb/hr
limit, which is intended to provide some restriction on the extent to
which the source could claim exclusions from the SCR-on rate. EPA has
identified issues with each of these limits as discussed in the
subsections below. EPA does allow for the possibility that different or
alternative emissions limits (AELs) can apply during different modes of
operation in the manner that PADEP has done here for the three
different limits described.\22\ However, EPA has stated that those AELs
``must be clearly stated components of the emission limitation, must
meet the applicable level of control required for the type of SIP
provision (e.g., be RACT for sources located in nonattainment areas)
and must be legally and practicably enforceable.'' \23\ Accordingly,
here EPA must evaluate whether this combination of limits satisfies the
OTR RACT requirement. PADEP did not provide any justification for why
these limits appropriately function as alternative emission limits. In
the 2015 SSM SIP Action, EPA recommended states consider seven criteria
when developing alternative emission limits.\24\ These recommended
criteria assure the alternative emission limitations meet basic CAA
requirements. PADEP did not explain why the alternative emission
limitations included in this SIP revision meet CAA requirements,
including RACT, and EPA cannot approve alternative emission limitations
without such a showing.
---------------------------------------------------------------------------
\22\ ``State Implementation Plans: Response to Petition for
Rulemaking; Restatement and Update of EPA's SSM Policy Applicable to
SIPs; Findings of Substantial Inadequacy; and SIP Calls To Amend
Provisions Applying to Excess Emissions During Periods of Startup,
Shutdown and Malfunction'' 80 FR 33840, section XI.D.
\23\ Ibid. P 33913.
\24\ Ibid. p. 33914.
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Further, PADEP developed the emissions limits for the Keystone,
Conemaugh and Homer City Facilities by reviewing only operating data
and emissions rates from a limited number of years.\25\ PADEP claims
that using emissions and operating data from a limited set of
relatively recent years is justified because these years reflect what
is currently possible due to aging
[[Page 13028]]
equipment and changes in operating patterns, including the impact of
changes made to the catalyst in the SCR system in order to meet the
requirements of the 2011 Mercury Air Toxics Standard (MATS) (Key RTC p.
8, Con RTC p. 9, and HC RTC p. 7).
---------------------------------------------------------------------------
\25\ EPA also notes an inconsistency in how PADEP discusses the
data that was considered in developing the limits at issue in this
SIP revision. In the RTCs, PADEP references data from 2016-2020.
(Key RTC p. 8, Con RTC p. 9, and HC RTC p. 7). However, in the TEMs,
PADEP references data from 2017-2020.
---------------------------------------------------------------------------
However, PADEP presented no data or analysis showing that aging
equipment, particularly the SCR control systems, have deteriorated such
that data from earlier years are unreliable. PADEP's submittals have
also not justified a rate selection methodology that relies on a
limited set of years, nor have they explained why the selected years
represent the lowest rate that can now be achieved when accounting for
such changes. Stated differently, the RACT limits (regardless of
averaging time) must reflect levels that represent periods of good
emissions control, not business as usual (e.g., a 5-year average of
past results) or higher-emitting periods.
Selection of the SCR-On lb/MMBtu Daily Average Emission Rates
PADEP's own data and analysis calls into question whether the final
SCR-on daily average lb/MMBtu rates for Conemaugh (0.070 lb/MMBtu),
Keystone (0.080 lb/MMBtu) and Homer City (0.080 lb/MMBtu for Units 1
and 2, and 0.070 lb/MMBtu for Unit 3) are RACT. Based on PADEP's SIP
submission, EPA cannot determine whether the SCR-on rates for any of
the three facilities are the lowest rates that can be achieved
considering technological and economic feasibility. Although PADEP
makes a general determination that optimization of the existing SCRs at
each facility is RACT, the data PADEP provided in its SIP submission do
not support a claim that these rates are the lowest achievable rates
that can reasonably be obtained at each unit when the SCRs are
operating, considering technological and economic feasibility. In
addition, PADEP then applies an upward adjustment to these rates to
account for factors, such as lag time, changes in boiler operating
patterns, and aging of equipment, that PADEP states it has already
accounted for by using data from 2017 to 2020 in their analyses for
setting the RACT limits. As such, there should be no needed upward
adjustment to account for these factors. Also, PADEP consistently
applies a compliance margin to its rates without explaining what the
margin is, in many cases, or why such a margin is needed to make the
selected limit technologically or economically feasible.
Conemaugh
For Conemaugh, PADEP asserts that it examined CAMD emissions and
other data for Units 1 and 2 for the years 2017-2020, but because both
units are similar, assumed that data from unit 1 applied to unit 2 and
therefore only discussed unit 1 data.\26\ Con TEM, pp. 3-4. Figure 1 in
the TEM is a graph showing percentage of heat input, NOX
emission rates and percentage of ammonia injection rates during May
2017. From this graph, PADEP determined that Conemaugh Unit 1
maintained a NOX emission rate of 0.045 lb/MMBtu from May
5th through May 18th, which PADEP attributed to an ammonia injection
control system operating at a set point of 0.045 lb/MMBtu. Con TEM, p.
4. From May 19th through the end of May 2017, PADEP observed that the
``relative difference between the ammonia injection rates and heat
input rates have increased,'' leading to a steady NOX
emission rate around 0.08 lb/MMBtu. Id. PADEP then notes that following
May 2017, unit 1 only operated with varying set points between 0.065
and 0.08 lb/MMBtu throughout the 2017 and 2018 ozone seasons. Con TEM,
p. 5. PADEP further observed that NOX rates increased
significantly in 2019 and provided a graph (Figure 2) which PADEP
asserts shows that during this month, Conemaugh ceased injecting
ammonia for NOX control at around 50% heat input, and even
when operating at 100% of heat input, the NOX emission rates
stayed around 0.1 lb/MMBtu. PADEP concluded that ``this strongly
suggests that additional emission reductions would be achieved if the
operator operated the SCR with a lower emission set point while the SCR
is running.'' Con TEM, p. 6. In addition, PADEP identified an April
2020 example when the SCR was not operating despite the boiler
operating at loads ``clearly supporting'' SCR operation, with
NOX emissions close to 0.3 lb/MMBtu during this time. Con
TEM, p. 7. From this PADEP concluded that ``[s]imply choosing not to
operate the SCR is not indicative of the control level achievable by
the system.'' Id. Based on this data, PADEP then selected an SCR-on
rate of 0.07 lb/MMBtu for Conemaugh. Id. The only explanation given for
this specific rate is that it ``includes a factor to provide an
appropriate compliance margin, fluctuations in load, any lag in the
control system as well as to account for other factors in the
facility's future operations.'' Con TEM, p. 8.
---------------------------------------------------------------------------
\26\ In response to a comment submitted on Conemaugh, PADEP
replied that during the 2018 ozone season, with a few exceptions,
Conemaugh's unit 2 was consistently able to achieve daily emission
levels in the .055-.07 lb NOX/MMBtu range. Con. RTC, p.
7.
---------------------------------------------------------------------------
The response to comments (RTC) document for Conemaugh adds
discussion of a 2017 study performed on unit 1 in May 2017 that
suggested that running the SCR with a set point of 0.04 lb/MMBtu caused
a spike in mercury emissions, and also discusses a 2016 study at the
end of ozone season on unit 2 that suggested running the SCR at a 0.050
lb/MMBtu set point also caused an increase in mercury emissions. RTC,
pp. 6-8. Based on further analysis, PADEP concluded that ``a setpoint
of 0.06 lb NOX/MMBtu . . . is achievable by [Conemaugh].''
RTC p. 8. However, the RTC states, without explanation, that PADEP is
choosing to keep the 0.07 lb NOX/MMBtu daily average
emission rate. RTC p. 8.
EPA finds that PADEP's explanation of why this limit meets the
definition of RACT is inadequate. Having concluded in the RTC that a
0.06 setpoint is achievable at Conemaugh, PADEP provides no explanation
as to why it selected 0.07 lb/MMBtu as the daily average SCR-on rate.
Nor is there any explanation of why a compliance margin is necessary,
what compliance margin was applied in this instance, how fluctuations
in load or lag in the control system affect the lowest achievable
emissions rate, and how or why the rate must be adjusted to account for
future operations. In the absence of an explanation of how PADEP
selected the specific 0.07 lb/MMBtu rate and how any of these other
factors affect the technical and economic feasibility of the lowest
rate identified, EPA cannot support PADEP's conclusion that the 0.07
lb/MMBtu daily average rate is RACT for when Conemaugh's SCRs are
operating.
Keystone
Like Conemaugh, PADEP's analysis for Keystone's SCR-on daily
average rate of 0.08 lb/MMBtu does not adequately explain why this rate
represents the lowest emission limit that Keystone's two units are
capable of meeting based on technological and economic feasibility. In
the TEM for Keystone, PADEP explains that it analyzed EPA's CAMD data
for Keystone Units 1 and 2 from 2017-2020. Key TEM, p. 3. The TEM then
includes a graph (Figure 1) showing certain daily operating statistics
for unit 2 for the month of May 2017, from which PADEP concludes that
unit 2 was able to maintain a NOX emission rate below 0.06
while the SCR was operating. TEM, p. 4. The TEM then shows a graph
(Figure 2) plotting certain
[[Page 13029]]
daily operating parameters for unit 1 during May 2017. TEM, p. 5. From
Figure 2, PADEP concludes that unit 1 was able to achieve a 0.05 lb/
MMBtu rate for ten days, but this rate increased to 0.09 lb/MMBtu for
the rest of the month because the operator elected to inject less
ammonia into the SCR system even though the heat input remained almost
constant at levels supporting SCR operation. Key TEM, p. 5. From this
and other data, PADEP concludes that both Keystone units can achieve an
SCR-on rate of 0.06 lb/MMBtu on a daily average basis.
The Keystone response to comments contains a long discussion of a
study Keystone submitted at some point in time purporting to show the
effects of trying to operate the SCRs at a NOx emission rate setpoint
of 0.05 to 0.06 lb/MMBtu during May 2017. Keystone RTC, p. 26. The RTC
notes that when Unit 2 attempted to operate at 0.055 lb/MMBtu for two
months in 2017, pressure drop across the air preheater increased to a
level requiring measures--in this case raising the SCR setpoint to 0.08
lb/MMBtu--to reduce the pressure drop. Id. at 27. The same study found
that operating unit 1's SCR at a 0.05 lb/MMBtu setpoint for only 15
days resulted in SCR catalyst fouling which prevented the SCR from
operating under 0.08 to 0.09 lb/MMBtu rates for the rest of the test
period. Id. The Keystone RTC then discusses at length the meaning of
the study and information submitted by another source and the effect of
different SCR set points on pressure drop, catalyst fouling, and the
ability to meet certain NOX emission rates. Key RTC, pp. 27-
30. PADEP concluded from these studies that Keystone should conduct a
future setpoint study to determine that optimal emission levels from
the SCR are achieved, but that based on the current evidence, the SCR
controls setpoint should be changed from 0.06 to 0.07 lb
NOX/MMBtu.\27\ Key RTC, p. 32. However, PADEP set a
NOX emission rate of 0.08 lb/MMBtu because ``varying load
conditions and other factors can and do affect SCR performance and
resulting NOX emission rates.'' TEM, p. 6.
---------------------------------------------------------------------------
\27\ The final unredacted permit does not mention this setpoint
study. Instead, Section E, Source Group Restrictions, subsection VI,
Work Practice Requirements, condition #012 requires that Keystone
submit a technical evaluation to PADEP on the possibility of heating
the flue gas prior to the SCR inlet to allow SCR operation at low
load levels. Keystone final permit, p. 172. This condition does not
appear in the redacted final permit submitted for inclusion into the
SIP.
---------------------------------------------------------------------------
EPA acknowledges that catalyst fouling and other similar factors
may affect the feasibility of SCR to achieve low rates. However,
similar to EPA's review of the Conemaugh limit, in the absence of an
explanation of how any of these other factors affect the technical and
economic feasibility of the lowest rate identified, EPA cannot support
PADEP's conclusion that the 0.08 lb/MMBtu daily average rate represents
RACT.
Homer City
Similar to EPA's assessment of the rates for Conemaugh and
Keystone, PADEP does not provide adequate justification for Homer
City's final SCR-on daily average rates of 0.08 lb/MMBtu for units 1
and 2 and 0.07 lb/MMBtu for unit 3 are the lowest emission limit that
these sources can meet based on technological and economic feasibility.
The TEM for Homer City explains that PADEP evaluated data from 2017-
2020 for all three units. PADEP notes that the unit 1 and 2 SCRs were
upgraded in 2018, and ``NOX emission rates significantly
improved,'' TEM, p. 6, but fails to explain why, in light of this,
PADEP thought consideration of 2017 data was appropriate. For units 1
and 2, PADEP notes that during 2019 and 2020 the SCRs were operated to
generally keep NOX emission rates at 0.10 lb/MMBtu, but also
identified periods of time when the NOX emission rate for
unit 2 went as low as 0.05 lb/MMBtu because more ammonia was being
injected. TEM, p. 5. The TEM states that other instances of between
0.05 and 0.10 lb/MMBtu were identified. TEM, p. 5. Looking at
additional data following the upgrade, PADEP suggested that ``had July
of 2020's ammonia injection rates matched that of July 2019,
significantly [sic] emissions reductions could have been achieved
during that timeframe.'' TEM p. 6. The TEM then states that ``[d]espite
the evidence presented,'' other factors such as load, exhaust
temperature, etc., and other unspecified factors ``can and do affect
SCR performance'' and require an operating limit above the never
specified achievable minimum. TEM, p. 8. PADEP then selected an SCR-on
rate of 0.08 lb/MMBtu as a daily average for units 1 and 2 but provided
no analysis or explanation why 0.08 lb/MMBtu is the lowest rate that
these units could meet based on technological and economic feasibility.
See TEM, pp. 4-9. The TEM also states that the rate includes an
unspecified factor to include a compliance margin, account for load
fluctuations, control system lags, and projected future changes in
operations. TEM, p. 9. In the RTC, PADEP seems to apply the
``findings'' from Keystone's attempt to operate the SCRs with a low
0.05 lb/MMBtu setpoint that such a setting leads to fouling of the air
preheater, high pressure drops, and SCR catalyst fouling before
determining that an emission rate of 0.08 lb/MMBtu will not cause these
problems at Homer City. RTC, p. 11.
For unit 3, the TEM states that there is evidence that unit 3 can
meet a NOX emission rate between 0.08 and 0.09 lb/MMBtu, but
limited evidence that it can meet a lower limit under certain
circumstances. TEM, p.10. Citing the same factors affecting SCR
performance as it cited for units 1 and 2, PADEP then concludes a value
above the minimum SCR rate is needed, but without explanation sets the
SCR-on daily average rate at 0.07 lb/MMBtu. TEM, p. 13. In their
response to comments document, PADEP seems to rely upon Keystone's
study of operating the SCRs at a low set point to support their
selection of the SCR-on limits for all the units. However, there is no
discussion of why the Keystone study can be applied to Homer City,
particularly given that Homer City seems to use an economizer bypass to
keep the SCRs operating at lower temperatures than might be possible at
Keystone.
Selection of the All Conditions 30-Day Rolling Average lb/hr Rate
The PADEP permits allow significant emissions to be excluded from
the daily lb/MMBtu SCR-on rate under a variety of conditions, and it is
necessary to evaluate whether the alternative emissions limits
applicable during these excluded conditions constitute RACT. Although
the PADEP permits contain a daily lb/MMBtu no-SCR rate, PADEP suggests
that the 30-day rolling average lb/hr rate is ``the glue'' that holds
the emissions limits together, and EPA acknowledges that it is a
critical component to the RACT justification because it establishes the
practical limitation on the extent to which the source can operate
without SCRs over an extended period of time. Accordingly, EPA must
evaluate whether PADEP's 30-day rolling average limit satisfies the
RACT requirement. EPA's assessment is that PADEP fails to clearly
demonstrate that the All Conditions 30-day rolling average lb/hr rate
necessitates that these facilities operate their SCRs to achieve the
lowest emission rate that is technologically and economically feasible,
which is required to meet the definitions of RACT.
PADEP asserts that the 30-day rate represents RACT because ``[a]t
any load above approximately 30%-40%, operation without control by the
SCR results in emissions greater than 700 lbs/hr.'' See, e.g., Con RTC
p. 6. This suggests that the SCR would be
[[Page 13030]]
necessary at higher loads, but it does not address the question of
whether it meets the RACT requirements when the facilities could run at
30-40% without using SCR. The EPA believes that it is possible that the
sources could operate at low loads while simultaneously meeting the
daily All Conditions lb/MMBtu rate and the 30-day lb/hr rate, thereby
creating a permissible way to avoid operating the SCR for long periods
of time. This resembles the 600-degree temperature SCR ``loophole,''
which the Third Circuit was highly critical of, that allowed facilities
to operate just below the temperature threshold at night when demand
was low and to avoid running the SCR. Sierra Club, 306. The 30-day lb/
hr all conditions rate does not appear to resolve this issue.
Furthermore, PADEP's justification for the All Conditions 30-day
lb/hr rates leave many specifics about the justification of the
selected rates unanswered. Each of PADEP's technical evaluation memos
have similar language stating ``[PADEP] evaluated and analyzed mass-
based NOX emission rate in pounds per hour on a 30-day
rolling average basis from EPA's Clean Air Markets Division (CAMD)
database at all operating conditions . . . from 2017-2020.'' PADEP then
presents a set of graphs for each unit depicting the 30-day average
rolling NOX emissions (lb/hr) overlaid with percentage of
maximum heat input (MMBtu). The time frames explored in these graphs is
summarized in table 2 of this document.
Table 2--Time Frames for 30-Day Average Data Provided by PADEP
----------------------------------------------------------------------------------------------------------------
Location in technical evaluation memo Facility Unit Time frame
----------------------------------------------------------------------------------------------------------------
pg. 16, figure 6...................... Conemaugh................ 1 May 2017-September 2017.
pg. 16, figure 6...................... Conemaugh................ 2 May 2017-September 2017.
pg. 14, figure 5...................... Keystone................. 1 May 2017-September 2017.
pg. 14, figure 5...................... Keystone................. 2 May 2017-September 2017.
pg 18, Figure 11...................... Homer City............... 1 January 2019-December 2021.
pg 18, Figure 11...................... Homer City............... 2 January 2019-December 2021.
pg 18, Figure 11...................... Homer City............... 3 January 2019-September 2020
(approximate).
----------------------------------------------------------------------------------------------------------------
None of these graphs displays data for the full 2017-2020 timeframe
PADEP evaluated and analyzed. Only the graphs from Homer City units
display data for more than a single year. PADEP's analysis then
consists of a qualitative description of the 30-day lbs/hr average the
units were able to achieve in the time frames in table 2 of this
document, but lacks data or description of what 30-day lb/hr all
conditions rates were observed outside of those time frames. Without
additional information about the 30-day average lb/hr rates achieved
during the four years PADEP analyzed, EPA cannot determine whether the
lb/hr limit selected for each unit represent an average of these years
of data, which the Sierra Club court found problematic, or the lowest
emissions in lb/hr which these sources achieved in this time frame,
considering technological and economic feasibility.
PADEP may or may not have reviewed a complete set of data from
2017-2020, but the analysis of this was not included in the technical
evaluation memos or the response to comment documents. As such, EPA
could not determine whether or this 30-day all conditions lb/hr rate
``. . . ensures that the operator will maximize operating hours with
the SCR and minimize heat input (and total mass emissions) when
operation of the SCR is technically infeasible.''
Additionally, the compliance buffer added to the 30-day lb/hr all
conditions rate does not appear to be sufficiently justified. PADEP
states in its Technical Evaluation Memo for Conemaugh ``[e]ach of
Conemaugh's units emits about 580 lb NOX per hour assuming
an emission level of .070 lb/MMBtu and 100% load. The impact to the
environment should never exceed this level on a long-term basis.'' Con
TEM p. 15. It would appear PADEP arrived at this number simply by
multiplying the daily SCR-on (lb/MMBtu) Rate by each boiler's rated
capacity (MMBtu/hr). Similar statements were made in the memos for
Keystone and Homer City. See table 3 of this document, for this
calculation for each boiler at Keystone, Conemaugh and Homer City. The
table also compares this to the permit limits contained in PADEP's 2022
SIP Submission, as well as a simple calculation of the percent increase
in those limits (a compliance buffer added by PADEP). However, no
explanation is given for why compliance buffers of 10-21% are needed,
or why certain units should receive more than double the buffer of
others.
Table 3--Compliance Buffers for PADEP's 30-Day All Conditions lb/hr Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rated Permit limit Calculated at Permit limit
Facility Unit capacity daily SCR-on capacity (lb/ 30-day avg. Compliance
(MMBtu/hr) (lb/MMBtu) hr) (lb/hr) buffer (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Conemaugh............................................... 1 8,280 0.070 580 700 21
2 8,280 0.070 580 700 21
Keystone................................................ 1 8,717 0.080 697 770 10
2 8,717 0.080 697 770 10
Homer City.............................................. 1 6,792 0.080 543 600 10
2 6,792 0.080 543 600 10
3 7,260 0.070 508 560 10
--------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 13031]]
EPA Approval Would Not Be Consistent With CAA Section 110(l)
Section 110(l) of the CAA prohibits the Administrator from
approving any SIP revision ``. . . if the revision would interfere with
any applicable requirement concerning attainment and reasonable further
progress (as defined in section 7501 of this title), or any other
applicable requirement of this chapter.'' For over 15 years, EPA has
interpreted section 110(l) as permitting approval of a SIP revision as
long as ``emissions in the air are not increased,'' thereby preserving
``status quo air quality.'' Ky. Res. Council, Inc. v. EPA, 467 F.3d
986, 991 (6th Cir. 2006); see also Indiana v. EPA, 796 F.3d 803, 806
(7th Cir. 2015); Ala. Env't Council v. EPA, 711 F.3d 1277, 1292-93
(11th Cir. 2013); Galveston-Houston Ass'n for Smog Prevention v. EPA,
289 F. App'x 745, 754 (5th Cir. 2008). This turns on EPA's interpreting
``interfere'' as meaning ``to hinder or make worse.'' Ky. Res. Council,
467 F. 3d at 995. The court in a recent Third Circuit decision
confirmed that a 110(l) analysis is not a one-size-fits-all provision
and the variables that must be analyzed depend on the particular
interference the SIP revision poses. Center for Biological Diversity v.
EPA, 75 F.4th 174, 181 (3rd Cir. 2023). Here, with the information
available to EPA, EPA could not determine that approval of the SIP
revisions at issue would not result in interference. Therefore, EPA
approval of these SIP revisions would not be consistent with section
110(l).
IV. Proposed Action
EPA's review of these materials indicates that Pennsylvania's May
2016 SIP Submittals for Keystone, Conemaugh and Homer City Generating
facilities: (1) do not adequately support Pennsylvania's justification
for the selection of RACT limits for the large EGU boilers; (2) lack
enforceable objective clear criteria for determining when emissions
from each EGU are subject to the SCR-on 24-hour average limit; and (3)
contain unbounded director's discretion provisions. For these, and
other reasons described above, EPA is proposing to disapprove
Pennsylvania's May 26, 2022 SIP revisions. EPA is soliciting public
comments on the issues discussed in this document. These comments will
be considered before taking final action.
V. Statutory and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a ``significant regulatory action'' as defined
by Executive Order 12866 and was therefore not submitted to the Office
of Management and Budget for review.
B. Paperwork Reduction Act (PRA)
This proposed action does not impose an information collection
burden under the PRA because it does not contain any information
collection activities.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action merely proposes to disapprove a SIP submission as not meeting
the CAA.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or tribal governments or the private sector.
E. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications as specified in
Executive Order 13175. This action does not apply on any Indian
reservation land, any other area where the EPA or an Indian tribe has
demonstrated that a tribe has jurisdiction, or non-reservation areas of
Indian country. Thus, Executive Order 13175 does not apply to this
action.
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 merely proposes to disapprove a SIP
submission as not meeting the CAA.
H. Executive Order 13211, Actions That Significantly Affect Energy
Supply, Distribution or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
I. National Technology Transfer and Advancement Act
This rulemaking does not involve technical standards.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
Executive Order 12898 (Federal Actions to Address Environmental
Justice in Minority Populations and Low-Income Populations, 59 FR 7629,
February 16, 1994) directs Federal agencies to identify and address
``disproportionately high and adverse human health or environmental
effects'' of their actions on minority populations and low-income
populations to the greatest extent practicable and permitted by law.
EPA defines environmental justice (EJ) as ``the fair treatment and
meaningful involvement of all people regardless of race, color,
national origin, or income with respect to the development,
implementation, and enforcement of environmental laws, regulations, and
policies.'' EPA further defines the term fair treatment to mean that
``no group of people should bear a disproportionate burden of
environmental harms and risks, including those resulting from the
negative environmental consequences of industrial, governmental, and
commercial operations or programs and policies.''
Under the CAA, the Administrator is required to approve a SIP
submission that complies with the provisions of the Act and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to review state choices,
and approve those choices if they meet the minimum criteria of the Act.
Accordingly, this proposed action disapproves state law as meeting
Federal requirements and does not impose additional requirements beyond
those imposed by state law.
The air agency did not evaluate environmental justice
considerations as
[[Page 13032]]
part of its SIP submittal; the CAA and applicable implementing
regulations neither prohibit nor require such an evaluation. EPA did
not perform an EJ analysis and did not consider EJ in this action. Due
to the nature of the action being taken here, this action is expected
to have a neutral to positive impact on the air quality of the affected
area. Consideration of EJ is not required as part of this action, and
there is no information in the record inconsistent with the stated goal
of E.O. 12898 of achieving environmental justice for people of color,
low-income populations, and Indigenous peoples. This action merely
proposes to disapprove a SIP submission as not meeting the CAA.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Intergovernmental relations, Nitrogen dioxide, Ozone,
Reporting and recordkeeping requirements, Volatile organic compounds.
Adam Ortiz,
Regional Administrator, Region III.
[FR Doc. 2024-03528 Filed 2-20-24; 8:45 am]
BILLING CODE 6560-50-P