74836 Federal Register / Vol. 89, No. 178 / Friday, September 13, 2024 / Rules and Regulations 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by November 12, 

2024. Filing a petition for 

reconsideration by the Administrator of 

this final rule does not affect the finality 

of this action for the purposes of judicial 

review nor does it extend the time 

within which a petition for judicial 

review may be filed, and shall not 

postpone the effectiveness of such rule 

or action. This action may not be 

challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2).) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Carbon monoxide, 

Incorporation by reference, 

Intergovernmental relations, Lead, 

Nitrogen dioxide, Ozone, Particulate 

matter, Reporting and recordkeeping 

requirements, Sulfur oxides, Volatile 

organic compounds. 

Dated: September 9, 2024. 

David Cash, 

Regional Administrator, EPA Region 1. 

Part 52 of chapter I, title 40 of the 

Code of Federal Regulations is amended 

as follows: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

Subpart EE—New Hampshire 

■ 2. Section 52.1519 is amended by 

adding paragraph (a)(12) to read as 

follows: 

§ 52.1519 Identification of plan-conditional 

approval. 

(a) * * * 

(12) On December 22, 2022, the New 

Hampshire Department of 

Environmental Services (NHDES) 

submitted a request to amend New 

Hampshire’s Env-A 300, ‘‘Ambient Air 

Quality Standards’’ regulation, as a 

revision to New Hampshire’s State 

Implementation Plan (SIP). NHDES 

revised this regulation to incorporate 

into its SIP revised National Ambient 

Air Quality Standards (NAAQS). On 

March 6, 2024, EPA strengthened the 

fine particulate matter (PM2.5) primary 

annual NAAQS. On May 16, 2024, New 

Hampshire submitted a letter to EPA 

committing to adopt a revised version of 

Env-A 300 which includes the current 

EPA PM2.5 primary annual NAAQS. 

* * * * * 

■ 3. In § 52.1520(c) the table ‘‘EPAApproved New Hampshire Regulations’’ 

is amended by revising the existing 

entry for ‘‘Env-A 300’’ to read as 

follows: 

§ 52.1520 Identification of plan. 

* * * * * 

(c) EPA approved regulations. 

EPA-APPROVED NEW HAMPSHIRE REGULATIONS

State citation Title/subject 

State 

effective 

date 

EPA approval date 1 Explanations 

*******

Env-A 300 .............. Ambient Air Quality Standards ................ 5/24/2022 7/13/2024 ................................................

[Insert Federal Register citation] ...........

..............................

* * * * * * * 

1 In order to determine the EPA effective date for a specific provision listed in this table, consult the Federal Register notice cited in this column for the particular provision. 

* * * * * 

[FR Doc. 2024–20721 Filed 9–12–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R03–OAR–2024–0024; FRL–11529– 

02–R3] 

Air Plan Approval; Pennsylvania; 

Attainment Plan for the Indiana 

Nonattainment Area for the 2010 1- 

Hour Sulfur Dioxide National Ambient 

Air Quality Standard 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is approving a state 

implementation plan (SIP) revision 

submitted by the Commonwealth of 

Pennsylvania (Pennsylvania or PA). The 

revision pertains to the attainment plan 

for the Indiana, PA nonattainment area 

for the 2010 1-hour sulfur dioxide (SO2) 

national ambient air quality standard 

(NAAQS). The EPA is approving these 

revisions to the Pennsylvania SIP in 

accordance with the requirements of the 

Clean Air Act (CAA). 

DATES: This final rule is effective on 

October 15, 2024. 

ADDRESSES: EPA has established a 

docket for this action under Docket ID 

Number EPA–R03–OAR–2024–0024. All 

documents in the docket are listed on 

the www.regulations.gov website. 

Although listed in the index, some 

information is not publicly available, 

e.g., confidential business information 

(CBI) or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available through www.regulations.gov, 

or please contact the person identified 

in the FOR FURTHER INFORMATION

CONTACT section for additional 

availability information. 

FOR FURTHER INFORMATION CONTACT: 

Megan Goold, 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) 814–2027. Ms. Goold 

can also be reached via electronic mail 

at goold.megan@epa.gov. 

SUPPLEMENTARY INFORMATION: 

I. Background 

On June 22, 2010, the EPA published 

a new 1-hour primary SO2 NAAQS of 75 

parts per billion (ppb) at 40 CFR 


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1 78 FR 47191 (August 5, 2013). 

2Sierra Club, et al. v. EPA, Case No. 20–3568 (3d 

Cir.). 

3Memorandum from Stephen D. Page, ‘‘Guidance 

for 1-Hour SO2 Nonattainment Area SIP 

Submissions’’, April 23, 2014. www.epa.gov/sites/ 

default/files/2016-06/documents/ 

20140423guidance_nonattainment_sip.pdf. 

50.17(a), which is met at an ambient air 

quality monitoring site when the 3-year 

average of the annual 99th percentile of 

daily maximum 1-hour average 

concentrations does not exceed 75 ppb, 

as determined in accordance with 40 

Code of Federal Regulations (CFR) part 

50 appendix T (75 FR 35520, June 22, 

2010). Under CAA section 107(d)(1), the 

EPA is required to designate areas as 

‘‘nonattainment,’’ ‘‘attainment,’’ or 

‘‘unclassifiable’’ within two years of 

establishing a new or revising an 

existing standard. As part of this 

process, states must submit 

recommendations for area designations 

and boundaries to the EPA within one 

year of the effective date of the standard. 

Effective on October 4, 2013,1 the 

Indiana, PA Nonattainment Area 

(hereafter referred to as ‘‘the Indiana, PA 

NAA’’) (which encompasses Indiana 

County, and Plumcreek Township, 

South Bend Township and Elderton 

Borough of Armstrong County) was 

designated as nonattainment for the 

2010 SO2 NAAQS. The area 

encompasses the primary SO2 emitting 

sources: the Keystone Generating 

Station (Keystone), Conemaugh 

Generating Station (Conemaugh), Homer 

City Generating Station (Homer City), 

and Seward Generating Station 

(Seward). The October 4, 2013, final 

designation triggered a requirement for 

Pennsylvania to submit by April 4, 2015 

(within 18 months per CAA section 

191(a)), a SIP revision with an 

attainment plan for how the Indiana, PA 

NAA would attain the 2010 SO2

NAAQS as expeditiously as practicable, 

but no later than October 4, 2018, (five 

years from the designation per CAA 

section 192(a)) in accordance with CAA 

sections 110(a), 172(c) and 191–192. 

For a number of areas, including the 

Indiana, PA NAA, the EPA published a 

March 18, 2016 Finding of Failure to 

Submit, with an effective date of April 

18, 2016, finding that Pennsylvania and 

other pertinent states had failed to 

submit the required SO2 attainment plan 

by this submittal deadline. (See 81 FR 

14736, March 18, 2016). This finding 

initiated a deadline under CAA section 

179(a) for the potential imposition of 

new source review and highway 

funding sanctions. However, as a result 

of Pennsylvania’s October 11, 2017 

submittal (hereafter referred to as ‘‘the 

2017 SIP submittal’’), and the EPA’s 

subsequent October 13, 2017 letter to 

Pennsylvania finding the submittal 

complete, the CAA section 179(a) 

sanctions were not imposed. 

Additionally, under CAA section 110(c), 

the March 18, 2016, finding triggered a 

requirement that the EPA promulgate a 

Federal implementation plan (FIP) 

within two years of the effective date of 

the finding unless, by that time, the 

state has made the necessary complete 

submittal, and the EPA has approved 

the submittal as meeting applicable 

requirements. The EPA took final action 

approving this attainment plan on 

October 19, 2020 (85 FR 66240, October 

19, 2020), which removed the FIP 

obligation. 

On December 18, 2020, the Sierra 

Club, Clean Air Council, and Citizens 

for Pennsylvania’s Future filed a 

petition for judicial review with the U.S. 

Court of Appeals for the Third Circuit, 

challenging that final approval.2 On 

April 5, 2021, the EPA filed a motion for 

voluntary remand without vacatur of its 

approval of the Indiana, PA SO2

attainment plan. 

On August 17, 2021, the U.S. Court of 

Appeals for the Third Circuit granted 

the EPA’s request for remand without 

vacatur of the final approval of 

Pennsylvania’s SO2 attainment plan for 

the Indiana, PA NAA, and required that 

the EPA take final action in response to 

the remand no later than one year from 

the date of the court’s order. 

On August 18, 2022, the EPA revised 

and corrected its prior full approval 

action (85 FR 66240, October 19, 2020) 

without further submission from 

Pennsylvania (effective September 19, 

2022) (87 FR 50778, August 18, 2022). 

Specifically, the EPA retained the 

approval of the emissions inventory and 

nonattainment new source review 

(NNSR) program requirements, and 

disapproved the attainment 

demonstration, reasonably available 

control measures and reasonably 

available control technology (RACM/ 

RACT) requirements, reasonable further 

progress (RFP) requirements, and 

contingency measures (hereafter 

referred to as the ‘‘2022 Partial 

Approval/Partial Disapproval’’) (87 FR 

50778, August 18, 2022). The partial 

disapproval action initiated a sanctions 

clock under CAA section 179, providing 

for emission offset sanctions for new 

sources if the EPA has not fully 

approved a revised attainment plan 

within 18 months (March 19, 2024) after 

final partial disapproval, and providing 

for highway funding sanctions if the 

EPA has not fully approved a revised 

plan within 6 months thereafter 

(September 19, 2024). The sanctions 

clock can be stopped only if the 

conditions of the EPA’s regulations at 40 

CFR 52.31 are met. Also, under CAA 

section 110(c), the partial disapproval 

action initiated an obligation for the 

EPA to promulgate a FIP within two 

years unless Pennsylvania has 

submitted, and the EPA has fully 

approved, a plan addressing the 

disapproved attainment planning 

requirements. 

On October 12, 2023, Pennsylvania 

submitted a 2023 SO2 Attainment Plan 

SIP Revision for the Indiana, PA NAA 

(hereafter referred to as the ‘‘2023 SIP 

submittal’’). The 2023 SIP submittal 

addresses the requirements of CAA 

sections 172(c), 191 and 192 and the 

disapproved attainment planning 

requirements in the EPA’s 2022 Partial 

Approval/Partial Disapproval. 

Specifically, this SIP revision contains a 

modified attainment demonstration 

using dispersion modeling, evaluates 

sources for RACT/RACM purposes, 

gives an RFP explanation, provides for 

contingency measures, and includes 

revised emissions limitations and 

control measures. 

Nonattainment area SO2 SIPs must 

meet the applicable requirements of the 

CAA, specifically CAA sections 110, 

172, 191 and 192. The EPA’s regulations 

governing nonattainment area SIPs are 

set forth at 40 CFR part 51, with specific 

procedural requirements and control 

strategy requirements residing at 

subparts F and G, respectively. Soon 

after Congress enacted the 1990 

amendments to the CAA, the EPA 

issued comprehensive guidance on SIPs 

in a document entitled the ‘‘General 

Preamble for the Implementation of title 

I of the Clean Air Act Amendments of 

1990,’’ published in the Federal 

Register at 57 FR 13498 (April 16, 1992) 

(General Preamble). Among other 

things, the General Preamble addressed 

SO2 SIPs and fundamental principles for 

SIP control strategies. Id. at 13545–49, 

13567–68. On April 23, 2014, the EPA 

issued guidance and recommendations 

for meeting the statutory requirements 

in SO2 SIPs addressing the 2010 primary 

NAAQS, in a document entitled, 

‘‘Guidance for 1-Hour SO2

Nonattainment Area SIP Submissions’’ 

(hereafter referred to as ‘‘2014 SO2

Nonattainment Guidance’’).3 In the 2014 

SO2 Nonattainment Guidance, the EPA 

described the statutory requirements for 

a complete nonattainment area SIP, 

which include an accurate emissions 

inventory of current emissions for all 

sources of SO2 within the 

nonattainment area; an attainment 

demonstration; enforceable emissions 

limitations and control measures; 


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demonstration of RFP; implementation 

of RACM (including RACT); 

nonattainment new source review; and 

adequate contingency measures for the 

affected area. 

For the EPA to fully approve a SIP as 

meeting the requirements of CAA 

sections 110, 172, 191, and 192 and the 

EPA’s regulations at 40 CFR part 51, the 

SIP for the affected area needs to 

demonstrate to the EPA’s satisfaction 

that each of the aforementioned 

requirements have been met. Under 

CAA sections 110(l) and 193, the EPA 

may not approve a SIP that would 

interfere with any applicable 

requirement concerning NAAQS 

attainment and RFP, or any other 

applicable requirement, and no 

requirement in effect before November 

15, 1990 (or required to be adopted by 

an order, settlement, agreement, or plan 

in effect before November 15, 1990), in 

any area which is a nonattainment area 

for any air pollutant, may be modified 

in any manner unless it ensures 

equivalent or greater emission 

reductions of such air pollutant. 

CAA section 172(c)(1) directs states 

with areas designated as nonattainment 

to demonstrate that the submitted plan 

provides for attainment of the NAAQS. 

40 CFR part 51, subpart G further 

delineates the control strategy 

requirements that SIPs must meet, and 

the EPA has long required that all SIPs 

and control strategies reflect the four 

fundamental principles of 

quantification, enforceability, 

replicability, and accountability. See 

General Preamble, 57 FR 13498 at 

13567–68 (April 16, 1992). SO2

attainment plans must consist of two 

components: (1) emission limits and 

other controls, including measures that 

assure implementation of permanent, 

enforceable and necessary emission 

controls, and (2) a modeling analysis 

which meets the requirements of 40 CFR 

part 51, appendix W and demonstrates 

that these emission limits and control 

measures provide for timely attainment 

of the primary SO2 NAAQS as 

expeditiously as practicable, but by no 

later than the attainment date for the 

affected area. In all cases, the emission 

limits and control measures must be 

accompanied by appropriate methods 

and conditions to determine compliance 

with the respective emission limits and 

control measures, and must be 

quantifiable (i.e., a specific amount of 

emission reduction can be ascribed to 

the measures), fully enforceable 

(specifying clear, unambiguous and 

measurable requirements for which 

compliance can be practicably 

determined), replicable (the procedures 

for determining compliance are 

sufficiently specific and non-subjective 

so that two independent entities 

applying the procedures would obtain 

the same result), and accountable 

(source-specific limits must be 

permanent and must reflect the 

assumptions used in the SIP 

demonstrations). 

II. Summary of SIP Revision and EPA 

Analysis 

On June 7, 2024 (89 FR 48523), the 

EPA published a notice of proposed 

rulemaking (NPRM) for Pennsylvania. In 

the NPRM, the EPA proposed approval 

of a revision to Pennsylvania’s SIP to 

demonstrate attainment of the 2010 SO2

NAAQS in the Indiana, PA NAA. As 

noted, Pennsylvania submitted the 

formal SIP revision on October 12, 2023. 

This submission includes 

Pennsylvania’s attainment 

demonstration and other attainment 

plan elements required under the CAA, 

including the requirement for meeting 

RFP toward attainment of the NAAQS, 

RACM/RACT, enforceable emission 

limitations and control measures, and 

contingency measures. Notably, the 

submission does not contain 

information regarding the required 

emissions inventory or the state’s NNSR 

program, as these were previously 

approved by the EPA (87 FR 50778, 

August 18, 2022). In this action, the EPA 

is determining that the Pennsylvania 1- 

hour SO2 attainment plan for Indiana, 

PA meets the applicable statutory and 

regulatory requirements and is thus 

approving Pennsylvania’s submission 

into its SIP. Also, the EPA is 

incorporating the following SO2

emission limits into the source-specific 

section of the PA SIP for the Keystone 

Plant, Conemaugh Station and Seward 

Station (as well as the compliance 

strategies listed in the unredacted 

portion of the Consent Order and 

Agreements (COAs) found in appendix 

C of the state submittal): 

• Keystone—Remove 9,600 lbs/hr on 

a 24-hour (daily) block average and 

replace with 8,328 lbs/hr combined 

based on a 24-hour block average for 

Boiler 1 & Boiler 2 (Source IDs 031 & 

032). 

• Seward—Remove 3,038.4 lbs/hr 

and replace with 2,895 lbs/hr combined 

based on a 30-day operating hours 

average rolling by one day for Source 

IDs 034 & 035. Remove 13,308 tpy and 

replace with 12,680 tpy combined for 

Source IDs 034 & 035. Add the 

requirement to inject limestone into 

Source ID 034 and Source ID 035 during 

initial firing each time Source ID 034 

and Source ID 035 are operated to 

reduce the magnitude and frequency of 

SO2 emission spikes in accordance with 

good air pollution control practices. 

• Conemaugh—Add 3,080 lbs/hr 

combined on a 3-hour block average for 

Units 1 & 2 (Source IDs 031 & 032). 

Other specific requirements of the 

Indiana County attainment plan and the 

rationale for the EPA’s action are 

explained in the NPRM, and its 

associated technical support document 

(TSD), and will not be restated here. 

III. EPA’s Response to Comments 

Received 

The EPA received four sets of 

comments in response to the NPRM. 

Two sets of comments were in 

opposition to the EPA’s proposed 

action. The EPA also received one 

comment in support of the EPA’s 

proposed action and one that was not 

relevant. 

Comment 1. The comment asserts that 

the EPA’s interpretation of what 

contingency measures are permissible in 

an SO2 attainment plan is not the ‘‘best 

reading’’ of the Clean Air Act. The 

comment cites section 172(c)(9), 

Contingency Measures, emphasizing 

that contingency measures take effect 

‘‘without further action by the State or 

Administrator.’’ The comment takes 

issue with the approach to SO2

contingency measures set forth in the 

EPA’s General Preamble, which states 

that ‘‘contingency measures’’ mean 

‘‘. . . the State agency has a 

comprehensive program to identify 

sources of violations of the SO2 NAAQS 

and to undertake an aggressive followup for compliance and enforcement.’’ 

See 57 FR 13498 at 13547 (April 16, 

1992). The comment asserts that an 

enforcement action is ‘‘further action,’’ 

which contradicts section 172(c)(9). 

Additionally, the comment claims that 

the EPA’s citation to the state’s 

authority to enforce its SIP is already 

required by CAA section 110(a)(2)(C) 

and does not necessarily meet the 

conditions of an enforcement program, 

let alone the contingency measure 

requirement, without a schedule and 

mechanism requiring action when 

violations occur. The comment suggests 

alternative contingency measures 

including switching to low-sulfur fuel, 

limiting operation until the SIP is 

revised, or a daily SO2 emission limit. 

Lastly, the comment states that the SIP 

lacks provisions to ensure ‘‘aggressive 

follow-up’’ can and will take place in 

the event the area fails to attain the 

NAAQS and therefore fails to meet the 

requirements of section 172(c)(9). 

Response 1. The EPA disagrees with 

this comment. 

First, as a general matter, the EPA’s 

longstanding approach to contingency 


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4SO2 Guideline Document, U.S. Environmental 

Protection Agency, Office of Air Quality Planning 

and Standards, Research Triangle Park, NC 27711, 

EPA–452/R–94–008, February 1994 (1994 SO2

Guideline); Guidance for 1-Hour SO2

Nonattainment Area SIP Submissions, Office of Air 

Quality Planning and Standards, Stephen D. Page, 

April 23, 2014 (2014 SO2 Nonattainment Guidance). 

5 87 FR 61514, 61522–61523 (October 12, 2022); 

84 FR 51988, 51994–51995 (October 1, 2019); 84 FR 

32672, 32677 (July 9, 2019) (final rule 84 FR 49659 

(September 23, 2019); 83 FR 51629, 51632–51633 

(October 12, 2018); 83 FR 40487, 40497 (August 15, 

2018) (final rules 85 FR 49967 (August 17, 2020) 

and 84 FR 10692 (March 22, 2019)); 82 FR 45242, 

45251 (September 28, 2017) (final rule 83 FR 25922 

(June 5, 2018)); 82 FR 40086, 40097–40098 (August 

24, 2017) (final rule 85 FR 73218 (November 17, 

2020)). 

6These measures enhance Pennsylvania’s fully 

approved enforcement program that serves to meet 

the contingency measure requirement, are not 

necessary to meet applicable requirements of the 

CAA under section 110(a)(2)(A), and are already 

included in the SIP. 

7Note the daily maximum 1-hour average 

concentration can be above 75 ppb multiple times 

in one year and still not violate the NAAQS due to 

the statistical nature of the design values. Therefore, 

this measure could be triggered multiple times 

before a design value of 75 ppb, and therefore a 

NAAQS violation, ever occurs. 

8These exceedance-activated and emissionsthreshold-activated measures were retained in the 

SIP, as explained in the partial disapproval, 87 FR 

15166, 15177 (March 17, 2022) (final rule published 

87 FR 50778 (August 18, 2022)), and the 2023 SIP 

submittal’s attainment plan reiterates these 

requirements and the plan will be included in the 

SIP. For the sake of clarity and consistency, 

Keystone’s COA will be removed from the SIP 

because the state has requested the removal of the 

9600 lb/hr 24-hr SO2 emission limit which was 

approved into the SIP via a source-specific SIP 

revision based on the COA; included in that COA 

is the emissions-threshold activated measure which 

in the COA is based on the previously disapproved 

emissions limit. With the approval of the 2023 

Continued 

measures in SO2 attainment plans, 

based on the Agency’s technical 

expertise and understanding of control 

strategies addressing SO2, has been 

consistently applied by the EPA and 

states since shortly after the enactment 

of the 1990 Clean Air Act Amendments, 

including in the General Preamble, 

updated guidance memoranda 4 and 

numerous SO2 SIP approval actions.5

Second, in response to the comment’s 

specific objection that contingency 

measures are to take effect ‘‘without 

further action,’’ the EPA has interpreted 

‘‘without further action’’ in the ozone, 

lead, and carbon monoxide contexts to 

mean no further rulemaking or 

legislative action, though the EPA 

recognized that certain actions such as 

notification of sources or modifications 

of permits would be needed for effective 

implementation. 57 FR 13498, 13512 

and 13533 (April 16, 1992), 58 FR 

67748, 67752 (December 22, 1993). 

Undertaking enforcement against 

sources for violations of emission 

limitations that were necessary to 

provide for SO2 NAAQS attainment is 

consistent with the EPA’s longstanding 

position across all of the NAAQS that 

ministerial actions to effectuate 

contingency measures, rather than 

additional rulemaking or legislative 

action to adopt new contingency 

measures, is appropriate to meet the 

requirements of CAA section 172(c)(9). 

To commence an enforcement action 

when an emission limitation violation is 

identified, no further administrative or 

legislative action is necessary, and the 

state can expeditiously proceed to 

remedy the violation—even without 

needing to wait to determine whether 

such violation has caused or contributed 

to a violation of the NAAQS in the 

nonattainment area. 

Contrary to the comment’s suggestion 

that Pennsylvania does not have a 

comprehensive enforcement program as 

required by CAA section 110(a)(2)(C), 

Pennsylvania has such a program as 

specified in section 4(27) of the 

Pennsylvania Air Pollution Control Act 

(APCA), 35 P.S. § 4004(27), which 

authorizes the Pennsylvania Department 

of Environmental Protection (PADEP) to 

take any action it deems necessary or 

proper for the effective enforcement of 

the Act and the rules and regulations 

promulgated thereunder. Such actions 

include the issuance of orders (i.e., 

enforcement orders and orders to take 

corrective action to address air pollution 

or the danger of air pollution from a 

source) and the assessment of civil 

penalties. Any person in violation of the 

APCA, the rules and regulations, any 

order of PADEP, or a plan approval or 

operating permit conditions could also 

be subject to criminal fines upon 

conviction under section 9, 35 P.S. 

§ 4009. Section 7.1 of the APCA, 35 P.S. 

§ 4007.1, prohibits PADEP from issuing 

plan approvals and operating permits 

for any applicant, permittee, or a general 

partner, parent or subsidiary 

corporation of the applicant or the 

permittee that is placed on PADEP’s 

Compliance Docket until the violations 

are corrected to the satisfaction of 

PADEP. Consequently, the EPA 

disagrees with the comment’s assertion 

that in order to credit PADEP’s 

comprehensive enforcement program as 

satisfying the CAA section 172(c)(9) SO2

contingency measure requirement, the 

program would have to include 

elements such as mandatory additional 

penalties or elimination of agency 

discretion to prosecute violations. 

Again, the enforcement process is 

more streamlined and targeted 

compared to rulemaking or legislation, 

which as discussed above, is considered 

disallowed ‘‘further action’’ for other 

criteria pollutants, and moreover 

enforcement is more akin to permissible 

implementation steps such as 

notification of sources and modification 

of permits. Compare 57 FR 13498, 

13547 (April 16, 1992) (discussing a 

comprehensive program to identify 

violations and undertaking aggressive 

follow-up for compliance and 

enforcement) with 57 FR 13498, 13512 

and 13533 (April 16, 1992) (interpreting 

‘‘without further action’’ to mean no 

further rulemaking or legislation but to 

allow implementation steps such as 

modification of permits and notification 

of sources) and 58 FR 67748, 67752 

(December 22, 1993). Thus, enforcement 

serves as an appropriate contingency 

measure for SO2 nonattainment SIPs. 

In addition to having a fully approved 

comprehensive enforcement program, 

PADEP has included what it refers to as 

additional contingency measures that 

are automatically triggered based on 

varying parameters, as described 

below.6 First, when any of the four 

sources’ emissions in the NAA reach 

99% of the SO2 emissions limit for the 

facility, within 48 hours the facility is 

required to undertake a full system 

audit of the SO2 emitting sources and 

submit a written report to PADEP 

within 15 days, and corrective actions 

shall be identified by PADEP as 

necessary. Second, if the Strongstown 

monitor in the NAA registers a daily 

maximum 1-hour average concentration 

exceeding 75 ppb, PADEP will notify 

the facilities in the NAA, and each 

facility is required to identify whether 

any of its SO2-emitting sources were 

running at the time of the exceedance, 

and within a reasonable time period 

leading up to the exceedance, not to 

exceed 24 hours. If any of the SO2- 

emitting sources were running at the 

time of the exceedance, the facility must 

then analyze the meteorological data on 

the day the hourly exceedance occurred 

to ensure that the exceedance was not 

due to SO2 emissions from the 

respective facility. The facility’s 

findings must be submitted to PADEP 

within 30 days of being notified of the 

exceedance.7 These emissionsthreshold-activated and exceedanceactivated measures further ensure that 

‘‘aggressive follow-up’’ will occur 

without further regulatory steps taken 

by the state. They also further reduce 

the likelihood of a violation of the 

emission limits or NAAQS. These 

measures are in line with the additional 

contingency measures the EPA 

mentions in the 2014 SO2

Nonattainment Guidance and in the 

General Preamble and are included in 

the Pennsylvania SIP.8 The most recent 


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attainment plan into the SIP, the emissionsthreshold activated measure and the exceedanceactivated measure for Keystone are still included in 

the SIP. 

9Memorandum from Sally L. Shaver, 

‘‘Attainment Determination Policy for Sulfur 

Dioxide Nonattainment Areas’’, January 26, 1996 

(1996 SO2 Memorandum). 

design values at the Strongstown 

monitor in the NAA are 19 ppb in 2022, 

22 ppb in 2021, and 25 ppb in 2020, 

which are well below the 1-hour 

primary 2010 SO2 NAAQS of 75 ppb. 

The proactive nature of PADEP’s 

emissions-threshold-activated and 

exceedance-activated measures, as well 

as the direct quantifiable impact of the 

SO2 control measures and the current 

design values in the NAA, make it very 

unlikely that a NAAQS violation could 

occur in this area while the sources are 

complying with their emission limits. 

The comment listed several options 

for contingency measures that the 

comment suggests should be included 

in the SIP. The EPA acknowledges that 

one or more of these options may be 

appropriate in a specific situation, and 

for a specific source, if the area fails to 

achieve RFP or fails to attain the 

NAAQS by the statutory attainment 

date. However, because Indiana, PA is a 

multisource area with several emission 

units per facility, requiring one or more 

of these measures may not be 

appropriate depending on the cause of 

the potential violations of the SO2

standard, which would need to be 

evaluated at the time of occurrence. For 

example, triggering a fuel-switch at one 

facility may not bring the area into 

attainment if the issue is caused by 

another facility violating its limit. 

Similarly, limiting operation of one 

facility may be appropriate if the subject 

facility is the cause of the problem, but 

requiring further measures at other 

facilities may not be warranted where 

the cause of the NAAQS violation was 

non-compliance with emission limits by 

a different facility and where the 

NAAQS violation can be most 

efficiently remedied by bringing that 

source into compliance with its 

established emission limits. Likewise, 

limiting operations at all SO2-emitting 

facilities in the area may not 

appropriately address the issue due to 

the localized nature of SO2 emissions 

and possible direct link between 

ambient concentrations and emissions 

from a specific facility. Similarly, 

changing the limits at all facilities, for 

example from a longer-term limit to a 

shorter-term limit, may appropriately 

address the problem, but it also may 

not, and the state would evaluate 

appropriate measures if and when an 

issue arises. These are illustrative 

examples, and while not exhaustive, 

they highlight the need for the state to 

be able to respond appropriately in a 

particular scenario due to the localized 

nature of SO2 impacts. 

In summary, the EPA’s longstanding 

approach to implementing the section 

172(c)(9) contingency measures 

requirement in SO2 attainment plans via 

comprehensive enforcement programs is 

appropriate. This approach is based 

upon the EPA’s technical expertise and 

in-depth understanding of SO2 control 

strategies and is consistent with the 

approaches undertaken for other criteria 

pollutants that have distinguished 

acceptable ministerial steps from 

regulatory or legislative action in 

satisfying the Act’s requirement that 

contingency measures take effect 

‘‘without further action.’’ Accordingly, 

in this case, Pennsylvania’s fully 

approved comprehensive enforcement 

program, and as bolstered by the state’s 

aforementioned requirements that are 

triggered automatically when emissions 

thresholds are reached or NAAQS 

exceedances are recorded, is approved 

as meeting the CAA section 172(c)(9) 

contingency measure requirement. 

Comment 2. A comment takes issue 

with the EPA’s approach to attainment 

determinations when an area initially 

fails to attain by the attainment date. 

The comment cites the requirement for 

the EPA to determine within six months 

of the attainment date whether the 

standard has been attained for a given 

area. Section 179(c)(1) of the Clean Air 

Act further states that if the 

Administrator has found that the area 

did not attain, the EPA ‘‘may revise or 

supplement such determination at any 

time based on more complete 

information or analysis concerning the 

area’s air quality as of the attainment 

date.’’ The comment notes that the 

EPA’s 1996 SO2 Memorandum 9 and 

2014 SO2 Nonattainment Guidance do 

not require a new SIP submittal and 

further modeling is not required if the 

source characteristics are ‘‘still 

reasonably represented.’’ The comment 

claims that the EPA ought to require 

states to submit a demonstration that 

modeling assumptions have not 

changed. The comment states that 

because neither the EPA nor the state 

are reevaluating modeling assumptions, 

there is an added responsibility on the 

public to comment on the record on 

proposed attainment determinations. 

Lastly, the comment notes that this 

issue is magnified by the improper use 

of 30-day rolling averages as emission 

limits, further complicating compliance. 

Response 2. This comment is outside 

the scope of this action and does not 

require a response. The EPA notes that 

in this action, it is not implementing 

CAA section 179(c) or making a 

determination of attainment by the 

attainment date. To the extent the 

comment relates to objections to the 

emission limits adopted in the 

attainment plan, as explained 

elsewhere, the EPA concludes that the 

plan will provide for attainment, 

accounting for worst-case allowable 

emissions and meteorology. 

Comment 3. The comment asserts that 

the EPA’s approach to reasonably 

available control measures (RACM) and 

reasonably available control technology 

(RACT) in the context of SO2 attainment 

plans is not the ‘‘best reading’’ of the 

Clean Air Act. The comment cites the 

EPA’s 2014 SO2 Nonattainment 

Guidance, stating that the requirement 

to implement all RACM is fulfilled if a 

plan provides for attainment of the SO2

standards. The comment then cites 

requirements for attainment plans, 42 

U.S.C. 7502(c)(1) (emphasis added): 

Such plan provisions shall provide for the 

implementation of all reasonably available 

control measures as expeditiously as 

practicable (including such reductions in 

emissions from existing sources in the area 

as may be obtained through the adoption, at 

a minimum, of reasonably available control 

technology) and shall provide for attainment 

of the national primary ambient air quality 

standards. 

In interpreting the provision, the 

comment highlights the word ‘‘and’’ in 

these nonattainment plan provisions, 

stating that the requirement for all 

RACM and RACT must be fulfilled and 

the requirement for attainment must 

also be met. The comment also states 

that the EPA must give effect to every 

word and phrase in a statutory 

provision and that the EPA has failed to 

give effect to the requirement that all 

RACM/RACT be implemented. Next, the 

comment claims that the EPA fails to 

consider the plain meaning of statutory 

terms in reference to ‘‘available’’ control 

options. The comment claims that the 

EPA’s proposal fails to determine 

whether additional controls are needed 

and is lacking an analysis of control 

efficiencies for existing and potential 

controls, as well as costs for upgrades. 

Response 3. In identifying the ‘‘best 

reading’’ of a statutory requirement, the 

EPA has considered the overall and 

specific purpose of the requirement, the 

technical context in which it is 

imposed, and the most reasonable 

manner in which its obligations may be 

fulfilled. The Clean Air Act 

nonattainment planning requirements in 

section 172(c) applicable to states are set 


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10RACT means devices, systems, process 

modifications, or other apparatus or techniques that 

are reasonably available taking into account: (1) The 

necessity of imposing such controls in order to 

attain and maintain a national ambient air quality 

standard; (2) The social, environmental, and 

economic impact of such controls; and (3) 

Alternative means of providing for attainment and 

maintenance of such standard. (This provision 

defines RACT for the purposes of 40 CFR 51.341(b) 

only.) 

11For reference, in the Indiana, PA NAA, 99.6% 

of the area’s SO2 emissions inventory comes from 

the four facilities controlled in the attainment plan. 

12The comment refers to the visibility program’s 

method of determining retrofit controls. However, 

the visibility program operates under a different 

statutory and regulatory framework, and SO2 is one 

of many visibility impairing pollutants. 

13 87 FR 61514, 61520–61521 (October 12, 2022); 

84 FR 32672, 32676–32677 (July 9, 2019) (final rule 

84 FR 49659 (September 23, 2019); 83 FR 50314, 

50321–50324 (October 5, 2018) (final rule 84 FR 

51988 (October 1, 2019)); 83 FR 12516, 12519– 

12520 (March 22, 2018) (final rule 83 FR 51629 

(October 12, 2018); 83 FR 40487, 40497 (August 15, 

2018) (final rules 85 FR 49967 (August 17, 2020) 

and 84 FR 10692 (March 22, 2019)); 82 FR 45242, 

45250–45251 (September 28, 2017) (final rule 83 FR 

25922 (June 5, 2018)); 82 FR 40086, 40096–40097 

(August 24, 2017) (final rule 85 FR 73218 

(November 17, 2020)). 

in place to provide for attainment and 

subsequent maintenance of the NAAQS 

in a designated nonattainment area— 

i.e., an area which the EPA has 

previously determined is not meeting 

the NAAQS. All section 172(c) 

requirements are targeted to remedy that 

NAAQS-violating occurrence. As the 

comment referenced, RACM/RACT is 

required under Clean Air Act section 

172(c)(1) for nonattainment areas. 

Section 172(c)(1) of the CAA requires 

the implementation of all RACM as 

expeditiously as practicable (including 

such reductions in emissions from 

existing sources in the area as may be 

obtained through the adoption, at a 

minimum, of RACT) and shall provide 

for attainment of the NAAQS. 

The comment suggests that the 

RACM/RACT requirement of section 

172(c)(1) requires a state to assess and 

adopt measures that go further than 

what is necessary to attain the SO2

NAAQS in the nonattainment area, but 

such an approach undercuts the 

purpose of this provision as applied in 

the SO2 nonattainment plan context. At 

its core, this RACM/RACT requirement 

serves to remedy the status quo 

situation of an area not meeting the 

NAAQS, in order to prospectively 

achieve NAAQS attainment. This is 

clear from the requirement’s placement 

within one of the two paragraphs in 

section 172(c)—along with section 

172(c)(6)’s requirement that the plan 

include emissions limitations as 

necessary to provide for NAAQS 

attainment—that specify enumerated 

remedial measures that are not 

otherwise required absent an area’s 

being designated nonattainment. 

Moreover, when applied in the SO2

nonattainment plan context, these 

provisions of section 172(c) must be 

read in concert with the other 

applicable statutory provision that 

Congress enacted in 1990 specifically 

governing SO2 plans, section 192(a), that 

similarly stressed the need for remedial 

implementation plans to provide for 

NAAQS attainment. As explained 

elsewhere and further below, for SO2

the EPA has long taken the technical 

view that this source-oriented pollutant, 

compared to more regional pollutants 

like ozone and particulate matter, can be 

addressed via identification of necessary 

emission limits, and the control 

measures needed to meet them, that will 

provide for attaining air quality. When 

that analysis has been undertaken and 

appropriate attainment-providing 

emission limits have been devised, the 

central purpose of the section 172(c) 

attainment planning requirements will 

have been fulfilled, and it is not 

necessary to require additional controls. 

Consequently, the EPA does not 

consider that it would be the ‘‘best 

reading’’ of the RACM/RACT 

requirement to interpret ‘‘reasonably’’ in 

section 172(c)(1), when applied in the 

SO2 SIP context, as requiring imposition 

of additional controls when those that 

are necessary to provide for NAAQS 

attainment have already been identified 

and required. 

For decades, the EPA has consistently 

defined RACT for SO2 as that control 

technology that will achieve the 

NAAQS within statutory timeframes. 

See, e.g., General Preamble, 57 FR 

13498, 13547 (April 16, 1992), which 

was published soon after the enactment 

of the 1990 Clean Air Act Amendments; 

see also, 1994 SO2 Guideline at 6–39. 

RACT for certain other criteria 

pollutants is control technology that is 

reasonably available considering 

technological and economic feasibility 

(see December 9, 1976 memorandum 

from Roger Strelow, ‘‘Guidance for 

Determining Acceptability of SIP 

Regulations in Non-Attainment Areas’’). 

The EPA’s definition of RACT for SO2,

as that control technology which is 

necessary to achieve the NAAQS (40 

CFR 51.100 (o)),10 is based on the 

specific characteristics of SO2. Since 

SO2 RACT is already defined as the 

technology necessary to achieve the SO2

NAAQS, control technology that failed 

to achieve the NAAQS would fail to be 

SO2 RACT, and control technology 

beyond what is necessary to attain the 

SO2 NAAQS would be beyond the 

central purpose of the nonattainment 

planning requirements of section 172(c). 

When determining RACT for SO2, it is 

appropriate to take into account the 

necessity of the control in meeting the 

standard. As noted, the EPA’s definition 

of RACT in the SO2 nonattainment 

context accounts for the characteristics 

of the specific pollutant. For a pollutant 

such as SO2, the relationship between 

an individual source’s emissions and 

the overall air quality can be explicitly 

quantified, and the emission reductions 

necessary to attain the NAAQS are 

based on a limited number of sources in 

a NAA.11 Therefore, a state can 

explicitly calculate the emission 

reductions necessary to provide for 

attainment of the SO2 NAAQS, and it is 

appropriate not to require states to 

impose control measures requiring 

further reductions beyond what is 

necessary to achieve attainment. 

For the Indiana, PA NAA, PADEP 

provided the necessary modeling, which 

demonstrated the specific hourly 

emission limits (and comparably 

stringent longer-term limits) that are 

required to provide for attainment of the 

standard. The EPA reviewed this 

modeling and determined it comports 

with the EPA’s Guideline on Air Quality 

Models (40 CFR part 51, appendix W) 

and the EPA’s 2014 SO2 Nonattainment 

Guidance. Therefore, the EPA 

concluded that the emission limits 

established as RACM were shown to 

provide for attainment and thus met the 

longstanding definition of RACT for 

SO2. PADEP implemented these 

emission limits as expeditiously as 

practicable (with Keystone’s and 

Conemaugh’s limits effective 

immediately after August 15, 2023, and 

Seward’s limits effective immediately 

after August 17, 2023 via Consent 

Orders and Agreements). 

While the comment disagrees with the 

EPA’s approach to RACM/RACT for SO2

and characterizes its version as a better 

reading of the Act, the comment does 

not explain why its reading of the Act 

is a better reading specific to the SO2

NAAQS. The comment does not address 

the specific characteristics of the 

pollutant, characteristics that the EPA 

has considered while it has consistently 

defined RACT for SO2.12

As discussed above, this has been the 

EPA’s longstanding definition and 

approach for SO2 RACT since the 1990 

Clean Air Act Amendments. The EPA 

has consistently applied this definition 

of SO2 RACT and promulgated 

numerous implementation plan 

approvals using this approach.13

Consequently, the EPA disagrees with 

the comment’s assertion that its 

approach does not reflect the ‘‘best 


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14www.epa.gov/sites/default/files/2016-06/ 

documents/20140423guidance_nonattainment_

sip.pdf. 

15The maximum modeled emission rate 

expressed as a 1-hour average that results in 

attainment is labeled the ‘‘critical emissions value’’ 

or CEV. 

16An ‘‘average year’’ is used to mean a year with 

average air quality. While 40 CFR part 50, appendix 

T, provides for averaging three years of annual 99th 

percentile daily maximum hourly values (e.g., the 

fourth highest maximum daily hourly concentration 

in a year with 365 days with valid data), this 

discussion and an example below uses a single 

‘‘average year’’ to simplify the illustration of 

relevant principles. 

reading’’ of Clean Air Act section 

172(c)(1) for SO2 implementation plans. 

Comment 4. Two comments claim 

that longer-term emission limits do not 

support attainment of the 1-hour SO2

standard. One comment states that the 

EPA’s 2014 SO2 Nonattainment 

Guidance 14 allows the use of 30-day 

emission limits as long as hourly 

emissions above the critical emission 

value 15 (CEV) are rare and if the 

magnitude of emissions do not 

significantly exceed the CEV. The 

comment further states that the EPA 

justified 30-day emission limits to allow 

for operational flexibility at sources. 

Next, the comment claims that the 

EPA’s 2014 SO2 Nonattainment 

Guidance highlights the value of 

supplemental limits, e.g., caps on the 

frequency or magnitude of elevated 

emissions, but fails to explain and 

justify approving longer-term emission 

limits in the absence of supplemental 

limits. Further, the comment states that 

the EPA’s recognition of the value of 

supplemental limits in the 2014 SO2

Nonattainment Guidance demonstrates 

that 30-day rolling averages, when used 

without supplemental limits, 

insufficiently protect the NAAQS. 

The second comment states that the 

SO2 limit was set as a 1-hour standard 

to protect human health from harmful, 

short-term exposures of SO2 and that 

Seward’s and Keystone’s emission 

limits are not protective under that 

standard. The comment claims that the 

Seward and Keystone generating 

stations ‘‘regularly and frequently’’ 

exceed their hourly CEV. Citing data 

from January 1, 2018 through March 31, 

2024, the comment asserts that Keystone 

exceeded the 9,718 lbs/hr CEV on 532 

occasions and that Seward exceeded the 

3,830 lbs/hr CEV on 349 occasions, 

which occurred on 28 separate days in 

2018, 7 days in 2019, 13 days in 2020, 

31 days in 2021, 58 days in 2022, 40 

days in 2023, and 16 days in 2024. The 

comment claims that the PADEP 

justification for disregarding these 

exceedances, i.e., because they 

‘‘occurred over a large number of 

possible operating hours per year,’’ is 

dismissive of the fact that the SO2

standard is a short-term standard and 

that just four hours on four days with 

SO2 concentrations over 75 ppb will 

lead to nonattainment of the NAAQS. 

Response 4. The EPA disagrees with 

the assertion that longer-term limits 

cannot be protective of a 1-hour SO2

standard. As explained in the NPRM for 

this action, and in the EPA’s 2014 SO2

Nonattainment Guidance, the EPA 

believes that appropriately set longerterm limits can be protective of the 1- 

hour SO2 NAAQS. 

The EPA acknowledges the concern 

that longer-term emission limits can 

allow short periods with emissions 

above the CEV, which, if coincident 

with meteorological conditions 

conducive to high SO2 concentrations, 

could in turn create the possibility of an 

hourly NAAQS exceedance occurring 

on a day when an exceedance would not 

have occurred if emissions were 

continuously controlled at the level 

corresponding to the CEV. However, for 

several reasons, the EPA believes that 

the approach recommended in its 

guidance document suitably addresses 

this concern. 

First, from a practical perspective, the 

EPA expects the actual emission profile 

of a source subject to an appropriately 

set longer-term average limit to be 

similar to the emission profile of a 

source subject to an analogous 1-hour 

average limit. The EPA expects this 

similarity because it has recommended 

that the longer-term average limit be set 

at a level that is comparably stringent to 

the otherwise applicable 1-hour limit 

(reflecting a downward adjustment from 

the CEV) and that takes the source’s 

emissions profile (and inherent level of 

emissions variability) into account. This 

downward adjustment of the limit is to 

compensate for the loss of stringency 

inherent in applying a longer-term 

average limit, by requiring most values 

to be lower than they are required to be 

with a 1-hour limit at the CEV. As a 

result, the EPA expects either form of 

emission limit to yield comparable air 

quality. 

Second, from a more theoretical 

perspective, the EPA has compared the 

likely air quality with a source having 

maximum allowable emissions under an 

appropriately set longer-term limit, to 

the likely air quality with the source 

having maximum allowable emissions 

under the comparable 1-hour limit. In 

this comparison, in the 1-hour average 

limit scenario, the source is presumed at 

all times to emit at the CEV, and in the 

longer-term average limit scenario, the 

source is presumed occasionally to emit 

more than the CEV, but on average, and 

presumably at most times, to emit well 

below the CEV. In an ‘‘average year,’’ 16

compliance with the 1-hour limit is 

expected to result in three exceedance 

days (i.e., three days with maximum 

hourly values above 75 ppb) and a 

fourth day with a maximum hourly 

value at 75 ppb. By comparison, with 

the source complying with a longer-term 

limit, it is possible that additional 

hourly exceedances would occur that 

would not occur in the 1-hour limit 

scenario (if emissions exceed the CEV at 

times when meteorology is conducive to 

poor air quality). However, this 

comparison must also factor in the 

likelihood that exceedances that would 

be expected in the 1-hour limit scenario 

would not occur in the longer-term limit 

scenario. This result arises because the 

longer-term limit requires lower 

emissions most of the time (because the 

limit is set below the CEV), so a source 

complying with an appropriately set 

longer-term limit is likely to have lower 

emissions at critical times than would 

be the case if the source were emitting 

as allowed with a 1-hour limit. 

To illustrate this point, the EPA 

conducted a statistical analysis using a 

range of scenarios using actual plant 

data. The analysis is described in 

appendix B of the EPA’s 2014 SO2

Nonattainment Guidance. Based on the 

analysis described in the 2014 SO2

Nonattainment Guidance, the EPA 

expects that an emission profile with 

maximum allowable emissions under an 

appropriately set, comparably stringent 

30-day average limit is likely to have the 

net effect of having a lower number of 

hourly exceedances and better air 

quality than an emission profile with 

maximum allowable emissions under a 

1-hour emission limit at the CEV. This 

result provides a compelling policy 

rationale for allowing the use of a longer 

averaging period in appropriate 

circumstances where the facts indicate 

this result can be expected to occur. 

The 2014 SO2 Nonattainment 

Guidance offers specific 

recommendations for determining an 

appropriate longer-term average limit. 

PADEP correctly followed the 

recommendations in devising the 

longer-term limits for Seward and 

Keystone. The 24-hour average limit of 

8,328 lbs/hr went into effect for 

Keystone on August 15, 2023, and the 

30-day average limit of 2,895 lbs/hr 

went into effect for Seward on August 

17, 2023. The EPA reviewed the 

comment’s hourly data files for Seward 

and Keystone from January 1, 2018 

through March 31, 2024, in which the 

CEV at Keystone was exceeded on 532 


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17According to the 2014 SO2 Nonattainment 

Guidance, p. 34, states have several additional 

options for restricting the frequency and magnitude 

of occurrences of elevated emissions. First, states 

may apply shorter averaging times, such as 24 

hours, which provide less allowance of emission 

spikes than would longer averaging times, such as 

30 days. Second, for sources that are or will be 

operating emission control equipment, states may 

establish requirements for the operation of this 

control equipment. For such sources, a substantial 

component of the variability in emissions often 

arises from variations in the operation of the control 

equipment, perhaps including operating the source 

when the control equipment is not operating. States 

have multiple options for requiring less variability 

in control equipment operation. One option would 

be a direct work practice requirement for operation 

of the control equipment, perhaps specifying some 

minimum level of control efficiency and associated 

monitoring, recordkeeping, and reporting 

requirements. 

18 If this type of information on historic emission 

patterns is not available, it may be difficult to 

determine supplemental limits. 

separate occasions, and the CEV at 

Seward was exceeded on 349 separate 

occasions. During the majority of this 

time period, the sources were not 

subject to the new limits developed for 

this attainment plan. Additionally, the 

stated number of occasions over the 

CEV for Seward and Keystone during 

the six and one quarter years of data 

equate to less than one percent of the 

hours for each source, which EPA 

considers to be a minimal amount of 

occasions over the CEV. The EPA 

disagrees with the comment on the air 

quality consequences of these occasions 

of elevated emissions. While there were 

times after the new 30-day limit went 

into effect where hourly emissions were 

above the CEV, there is no evidence that 

these emissions caused an exceedance 

of the NAAQS. The EPA believes that a 

full analysis of the air quality impact of 

Pennsylvania’s limits must consider 

these hours of elevated emissions in 

conjunction with the far greater number 

of hours when emissions are required to 

be well below the level that would 

model violations (i.e., the CEV). The 

comment provided no modeling 

analysis that incorporated both the 

hours of emissions above the CEV and 

the hours below. For reasons described 

in more detail in the EPA’s guidance, 

the NPRM and the EPA’s Technical 

Support Document: Critical Emission 

Value Modeling Analysis for the 

Indiana, PA 1-Hour SO2 Nonattainment 

Area (EPA Modeling TSD) for this 

action, the EPA believes that the net 

effect of these compensating factors is 

that PADEP’s limits provide adequate 

assurance that the area will attain the 

SO2 standard. 

The EPA disagrees with the 

comment’s assertion that supplemental 

limits must be required to limit the 

magnitude of emissions spikes when a 

longer-term limit is established. As 

explained in detail above, a comparably 

stringent longer-term limit can provide 

for protection of the NAAQS, even 

without supplemental limits. In any 

event, PADEP exercised additional 

options for restricting the frequency and 

magnitude of occurrences of elevated 

emissions per the 2014 SO2

Nonattainment Guidance,17 such as 

setting averaging times shorter than 

thirty days or analyzing emissions 

data 18 to determine when to target 

emission episodes using supplemental 

limits. For Keystone, PADEP applied a 

shorter averaging time of 24 hours. For 

Seward, which has a 30-day limit, 

PADEP included a supplemental limit 

in the form of a work practice 

requirement of injecting limestone into 

the combustor during initial firing 

which was deemed appropriate due to 

specific emissions data patterns 

experienced during those periods. 

Comment 5. The comment states that 

the CEVs set for each stationary SO2

source impacting nonattainment in 

Indiana County are not protective of the 

NAAQS. The comment cites an 

assessment of the EPA’s modeling 

analysis which asserts that the CEVs 

yield peak concentrations 

approximately 50 micrograms per cubic 

meter above the NAAQS. Steven Klafka, 

Conemaugh, Homer City, Keystone and 

Seward Generating Stations Indiana 

County, Pennsylvania Evaluation of 

Compliance with the 1-hour NAAQS for 

SO2, (Wingra Engineering July 8, 2024). 

Response 5: The EPA has reviewed 

the July 8, 2024 modeling analysis 

prepared for the Sierra Club by Wingra 

Engineering (July 2024 Wingra Analysis) 

and found several deficiencies with it. 

These include the choice of 

meteorological data and the combining 

of emission sources across an 

amalgamated modeling domain. The 

July 2024 Wingra Analysis otherwise 

utilizes the same modeling system 

components (receptor grid locations/ 

elevations/hill-height scales, building 

downwash parameters, surface 

characteristics, etc.) as those used in the 

modeling analysis performed by 

Pennsylvania and reviewed by the EPA. 

For consistency purposes, the 

comment’s July 2024 Wingra Analysis 

utilized the same versions of the 

AERMOD platform used by 

Pennsylvania. 

As described in section 6 of PADEP’s 

Air Dispersion Modeling Technical 

Support Document (Docket file EPA– 

R03–OAR–2024–0024–0003_

attachment_9) the air dispersion 

modeling for the Indiana, PA NAA 

utilized representative meteorological 

datasets from two sites. Data from the 

Johnstown-Cambria County Airport 

(KJST) meteorological site represented 

atmospheric conditions in the vicinity 

of Keystone and Homer City power 

plants. The KJST meteorological site is 

approximately 58 kilometers southeast 

of Keystone and approximately 38 

kilometers southeast of Homer City. 

Data from the Ash Site #1 

meteorological site represented 

atmospheric conditions in the vicinity 

of Conemaugh and Seward. The 

Conemaugh-Seward (Ash Site #1) 

meteorological site is located between 

the two power plants, approximately 1.9 

kilometers northeast of the Conemaugh 

power plant and approximately 1.7 

kilometers south-southwest of the 

Seward power plant. 

Based on the EPA’s Guideline on Air 

Quality Models (40 CFR part 51, 

appendix W), meteorological data used 

as input to a dispersion model should 

be selected on the basis of spatial and 

climatological (temporal) 

representativeness as well as the ability 

of the individual parameters selected to 

characterize the transport and 

dispersion conditions in the area of 

concern. Representativeness of the 

meteorological data is dependent on 

numerous factors. These factors include 

but are not limited to: (1) the proximity 

of the meteorological monitoring site to 

the area under consideration; (2) the 

complexity of the terrain; (3) the 

exposure of the meteorological 

monitoring site; and (4) the period of 

time during which data are collected. 

Both meteorological data sets used in 

Pennsylvania’s modeling analysis meet 

applicable completeness requirements. 

While the July 2024 Wingra Analysis 

claims that the Ash Site #1 is 

representative of impacts from 

emissions released by all four plants, 

the EPA disagrees because of the 

difference in local topography around 

the modeled sources. The decision to 

utilize the KJST meteorological site for 

the Homer City and Keystone power 

plants and the Ash Site #1 for the 

Conemaugh and Seward power plants 

was largely based on the modeled 

sources’ topographical settings (terrain 

features). Each of the meteorological 

sites were best suited to capture the 

proper boundary layer characteristics 

for their respective sources. 

The Indiana, PA NAA sits along the 

Allegheny Plateau physiographic 

province of the Appalachian Mountains 

system west of the eastern continental 

divide. Maps depicting topographical 

elevations in the vicinity of the Indiana, 

PA NAA showing the locations of the 

Conemaugh, Homer City, Keystone and 

Seward power plants and the KJST and 


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19After a change of ownership in December 2016, 

Seward implemented a startup operational change, 

which is the addition of limestone to the combustor 

during initial firing to reduce SO2 emissions. 

Ash Site #1 meteorological sites can be 

found in the EPA’s technical support 

document that is part of the public 

record in the docket for this action 

(Figures 1 and 2 of the EPA Modeling 

TSD). Relatively flat terrain resides in 

the western portion of the 

nonattainment area where the Homer 

City and Keystone power plants are 

located. Both power plants sit at 

significantly lower elevations than the 

KJST site. Furthermore, the KJST site is 

located on some of the highest terrain in 

western Pennsylvania and no 

topographic features between the KJST 

site and Homer City and Keystone 

would unduly influence the wind fields 

at the KJST site. In contrast, the 

Conemaugh and Seward power plants 

are located along the Conemaugh River 

in the southeastern part of the Indiana, 

PA NAA between the Chestnut (west) 

and Laurel (east) ridges that define the 

northern terminus of the Ligonier 

Valley. The latter two power plants 

reside within a valley marked by higher 

terrain to the east and west. This valley 

impacts local meteorological parameters 

such as wind fields and atmospheric 

stability. Air flow can become 

channeled within valley features, and 

topography can influence vertical 

atmospheric stability, especially at 

night, setting up potentially strong 

vertical temperature inversions. 

The July 2024 Wingra Analysis 

amalgamates all of the model receptors 

Pennsylvania utilized in its three 

modeling domains covering the entire 

Indiana, PA NAA. The rationale for 

dividing the Indiana, PA NAA into three 

separate modeling domains (with 

different sources and meteorological 

data) was explained in the Air 

Dispersion Modeling Technical Support 

Document from PADEP (pages 6–8 to 6– 

9, 6–15 to 6–17, and 8–1 to 8–3) and in 

the EPA Modeling TSD (pages 63 and 

70) that are part of the public docket for 

this action. 

No rationale was provided in the July 

2024 Wingra Analysis submitted during 

the public comment period to support 

combining the three modeling domains 

utilized in PADEP’s SIP modeling 

demonstration. Additionally, no 

rationale was provided to refute the 

division of the Indiana, PA NAA into 

three distinct modeling domains. The 

EPA believes, therefore, that Wingra 

Engineering’s modeling analysis erred 

on its modeling domain setup by 

combining all sources into one 

amalgamated receptor domain. 

Noting the deficiencies in the July 

2024 Wingra Analysis, the EPA 

concludes that the modeling analysis 

presented by PADEP demonstrates the 

validity of the CEVs established for the 

Conemaugh, Homer City, Keystone and 

Seward power plants. 

Comment 6. The comment states that 

the adjustment factor of 0.756, used to 

convert the Seward generating station’s 

CEV to a 30-day rolling average, is too 

high. The comment claims that 

Pennsylvania’s proposed adjustment 

factor results in 20% higher emission 

limits when compared to emission 

limits calculated with the EPA’s 

adjustment factor of 0.63. The comment 

states that if the January 2019 through 

March 2023 dataset is used instead of 

the 2018–2021 dataset used by PADEP, 

the Seward adjustment factor would be 

reduced to 0.712. Next, the comment 

provided seven different adjustment 

factors calculated based on differing 

historic data periods. Additionally, the 

comment asserts that Seward’s SO2

emissions have increased since 2013, 

and the proposed 30-day limit increases 

the likelihood of continued 

nonattainment if emission reductions 

are not established. 

Response 6. The spreadsheet 

submitted as Attachment C to the 

comment, included incorrect 

calculations for the 30-day average 

values. As specified in the state 

submittal, the 30-day rolling average for 

Seward should be calculated for each 

operating day, by calculating the 

average of all the hourly emission data, 

using only hours during which fuel is 

combusted from the preceding 30 

operating days. In the spreadsheet 

calculations, the comment always 

averaged the previous 30-days using 720 

hours (total number of hours in 30 days) 

as opposed to the number of hours 

when fuel was actually burned. In the 

SIP submittal, PADEP correctly 

calculated the 30-day average emission 

values in developing the adjustment 

factors for Seward. PADEP also justified 

the period of time used for the 

calculations by explaining that, in line 

with the EPA’s 2014 SO2 Nonattainment 

Guidance, PADEP used data from years 

of stable operation. As PADEP 

described, when the SIP analysis began 

in 2022, it initially considered emission 

data for years 2017 through 2021. 

However, in 2017, there was an 

operational change at Seward 19 that 

could have affected the emission 

variability. Because of operational 

changes at Seward in 2017 and in an 

effort to have one consistent emission 

dataset for all three facilities with 

longer-term SO2 emission limits, PADEP 

calculated the adjustment factors using 

emission data for years 2018 through 

2021. The EPA believes this is 

consistent with the recommendation on 

emission data use in the 2014 SO2

Nonattainment Guidance, pages 29–30. 

Also, the comment appears to 

misunderstand the adjustment factor of 

0.63 included in table 1 of appendix B 

of the 2014 SO2 Nonattainment 

Guidance. The EPA’s 2014 SO2

Nonattainment Guidance did not 

calculate nor provide source-specific 

adjustment factors for Seward, but 

rather, calculated the average 

adjustment factor for 90 sources 

equipped with a dry scrubber. The EPA 

believes that if continuous emissions 

monitoring systems (CEMs) data is 

available for a source, it is most 

appropriate to use that data for 

developing adjustment factors, as long 

as it continues to represent the 

distribution of emissions that is 

expected once the attainment plan is 

implemented. This was the case with 

Seward. The EPA concludes that the 

adjustment factor of 0.756 calculated for 

Seward is more appropriate because it is 

source-specific, based on CEMS data 

and provides for a comparably stringent 

30-day average emission limit. 

Regarding the comment about the 

annual SO2 emissions increases since 

2013, the EPA reviewed the data and 

notes that SO2 emissions increased from 

2013–2018. However, after that period 

the emissions remained in a similar 

range. Additionally, annual emissions 

are not a direct indicator of compliance 

with the NAAQS nor with the 30-day 

emission limit which the EPA is 

approving as providing for attainment in 

this plan. 

Comment 7. The comment claims that 

the EPA ignores the ongoing negative 

impacts of Indiana County’s major SO2

sources on neighboring Westmoreland 

and Cambria counties. The comment 

states that Pennsylvania has failed to 

meaningfully address SO2 sources in 

Indiana County and that the EPA should 

encourage Pennsylvania to implement 

more protective SO2 limits to wholly 

address nonattainment caused by these 

sources and to be protective of 

vulnerable populations in Indiana 

County and neighboring areas. 

Response 7. The comment’s concern 

regarding negative impacts outside of 

the Indiana, PA NAA boundaries from 

the Indiana County SO2 sources is 

beyond the scope of this action. 

Section 171(2) of the CAA defines 

nonattainment area to mean for any air 

pollutant, an area which is designated 

‘‘nonattainment’’ with respect to that 

pollutant within the meaning of section 

107(d) of this title. In an earlier, separate 

action, the boundaries of the Indiana, 


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20 78 FR 47191 (August 5, 2013); www.epa.gov/ 

sulfur-dioxide-designations/so2-designations-statedesignations-round-1. 

21EPA designated Cambria County unclassifiable 

and Westmoreland County attainment/ 

unclassifiable for the 2010 1-hour SO2 NAAQS 

effective April 9, 2018. 83 FR 1098 (January 9, 

2018). 22 62 FR 27968 (May 22, 1997). 

PA NAA were set and finalized in 

August 2013 in ‘‘Round One’’ of EPA’s 

designations for the 2010 SO2 NAAQS 

under section 107(d) of the CAA, and 

these boundaries were not challenged.20

Westmoreland and Cambria counties are 

not included within those boundaries. 

Pennsylvania’s obligation under 

section 110(a) of the CAA is to submit 

‘‘ . . . a plan which provides for 

implementation, maintenance, and 

enforcement of such primary standard 

in each air quality control region (or 

portion thereof) within such State.’’ 

CAA section 110(a)(1). Section 110 

further provides that ‘‘[i]n the case of a 

plan or plan revision for an area 

designated as a nonattainment area, [the 

plan shall] meet the applicable 

requirements of part D of this 

subchapter (relating to nonattainment 

areas).’’ CAA section 110(a)(2)(I). 

Section 172(c)(6) then requires the SIP 

for a nonattainment area to include 

enforceable emission limitations and 

control measures as necessary or 

appropriate to provide for NAAQS 

attainment ‘‘in such area.’’ In this case, 

Pennsylvania’s attainment plan for the 

Indiana, PA NAA includes limits on 

SO2 sources and a modeling 

demonstration showing that SO2

concentrations throughout the 

nonattainment area are at or below the 

NAAQS. 

Further, the EPA’s role is limited to 

determining whether the submitted SIP 

meets the requirements of the CAA, see 

section 110(k)—in this action, 

Pennsylvania’s 2023 SIP submittal does 

not address areas outside the defined 

nonattainment area. Absent a clear 

requirement that Pennsylvania must 

include model receptors outside of the 

nonattainment area in its submission, 

the EPA will confine its analysis to 

whether the attainment SIP 

demonstrates attainment within the 

designated nonattainment area. 

On February 12, 2024, EPA published 

notice in a separate action of its intent 

to redesignate portions of Cambria and 

Westmoreland Counties 21 to 

nonattainment for the 2010 SO2 NAAQS 

(89 FR 9815). The CAA provides the 

EPA with the authority to revise 

designations of, or ‘‘redesignate,’’ areas 

under CAA section 107(d)(3). Such 

redesignations can originate as requests 

by states (per CAA section 107(d)(3)(D)), 

and the EPA can also notify a state at 

any time that a designation of any area 

or portion of an area should be revised, 

on the basis of air quality data, planning 

and control considerations, or any other 

air quality-related considerations the 

EPA Administrator deems appropriate. 

If finalized, the nonattainment 

designation for these counties will 

require the state to submit 

nonattainment area requirements per 

CAA section 172. 

Comment 8. The comment states that 

the SIP should incorporate the closure 

of the Homer City generating station, as 

well as the projected 2028 retirements of 

the Keystone and Conemaugh 

generating stations. Further, the 

comment asserts that the SIP should not 

be approvable until the SO2 emission 

limits for these plants are removed. 

Response 8. The EPA disagrees with 

the comment. CAA section 172(c)(6) 

requires the SIP for a nonattainment 

area to include enforceable emission 

limitations and control measures as 

necessary or appropriate to provide for 

NAAQS attainment in the area. With 

this action, the EPA is approving the 

emission limits for the four sources in 

the Indiana, PA NAA as meeting this 

requirement. As such, it is not necessary 

to include the Homer City retirement 

nor the projected retirements of 

Keystone and Conemaugh in the SIP as 

enforceable measures. And as explained 

in the NPRM, as the EPA is not aware 

of PADEP rescinding Homer City’s 

operating permit, Homer City ceasing 

operations does not guarantee that the 

units are permanently and enforceably 

shutdown. 89 FR 48523, 48528 (June 7, 

2024). Nor did PADEP’s 2023 SIP 

submittal request to incorporate the 

pending closure of Homer City into the 

SIP. Similarly for Keystone and 

Conemaugh, the EPA is not aware of 

PADEP rescinding the permits for these 

two sources nor did PADEP’s 2023 SIP 

submittal request their projected 

retirements be included in the SIP. The 

approval of this attainment plan is thus 

properly based on Homer City’s possible 

continued operation, as well as 

Keystone’s and Conemaugh’s continued 

operations. 

IV. Final Action 

The EPA is approving the attainment 

plan for the Indiana, PA NAA for the 

2010 1-hour SO2 NAAQS, which 

Pennsylvania submitted on October 12, 

2023, as a revision to the Pennsylvania 

SIP. Specifically, the EPA is approving 

the attainment demonstration, RACM/ 

RACT requirements, RFP requirements, 

and contingency measures of the 

attainment plan. The EPA previously 

approved the emissions inventory and 

NNSR program elements of the 

attainment plan. 

This approval terminates the highway 

funding sanction and FIP clocks started 

under CAA sections 179 and 110, 

respectively, resulting from EPA’s 

partial disapproval of the prior SIP 

submittal. It also removes the permitting 

offset sanction that has been in place 

since March 19, 2024. 

V. Incorporation by Reference 

In this document, the EPA is 

finalizing regulatory text that includes 

incorporation by reference. In 

accordance with requirements of 1 CFR 

51.5, EPA is finalizing the incorporation 

by reference of SO2 emission limits and 

compliance parameters established in 

(the unredacted portions of) the COAs 

for the Seward, Conemaugh and 

Keystone facilities, as discussed in 

section II of this preamble and described 

in the amendments to 40 CFR part 52 set 

forth below. The EPA has made, and 

will continue to make, these materials 

generally available through 

www.regulations.gov and at the EPA 

Region III Office (please contact the 

person identified in the FOR FURTHER

INFORMATION CONTACT section of this 

preamble for more information). 

Therefore, these materials have been 

approved by the EPA for inclusion in 

the SIP, have been incorporated by 

reference by the EPA into that plan, are 

fully federally enforceable under 

sections 110 and 113 of the CAA as of 

the effective date of the final rulemaking 

of the EPA’s approval, and will be 

incorporated by reference in the next 

update to the SIP compilation.22

VI. Statutory and Executive Order 

Reviews 

A. General Requirements 

Under the CAA, the Administrator is 

required to approve a SIP submission 

that complies with the provisions of the 

CAA 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 approve state choices, 

provided that they meet the criteria of 

the CAA. Accordingly, this action 

merely approves state law as meeting 

Federal requirements and does not 

impose additional requirements beyond 

those imposed by state law. For that 

reason, this action: 

• Is not a significant regulatory action 

subject to review by the Office of 

Management and Budget under 

Executive Orders 12866 (58 FR 51735, 

October 4, 1993) and 13563 (76 FR 3821, 

January 21, 2011); 


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• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); and 

• Is not subject to requirements of 

section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the CAA. 

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. The 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.’’ The 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.’’ 

PADEP did not evaluate 

environmental justice considerations as 

part of its SIP submittal; the CAA and 

applicable implementing regulations 

neither prohibit nor require such an 

evaluation. The 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. 

In addition, this final rule approving 

Pennsylvania’s Indiana, PA NAA SO2

attainment plan does not have tribal 

implications as specified by Executive 

Order 13175 (65 FR 67249, November 9, 

2000), because the SIP is not approved 

to apply in Indian country located in the 

State, and the EPA notes that it will not 

impose substantial direct costs on tribal 

governments or preempt tribal law. 

B. Submission to Congress and the 

Comptroller General 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. The EPA will 

submit a report containing this action 

and other required information to the 

U.S. Senate, the U.S. House of 

Representatives, and the Comptroller 

General of the United States prior to 

publication of the rule in the Federal 

Register. A major rule cannot take effect 

until 60 days after it is published in the 

Federal Register. This action is not a 

‘‘major rule’’ as defined by 5 U.S.C. 

804(2). 

C. Petitions for Judicial Review 

Under section 307(b)(1) of the CAA, 

petitions for judicial review of this 

action must be filed in the United States 

Court of Appeals for the appropriate 

circuit by November 12, 2024. Filing a 

petition for reconsideration by the 

Administrator of this final rule does not 

affect the finality of this action for the 

purposes of judicial review nor does it 

extend the time within which a petition 

for judicial review may be filed, and 

shall not postpone the effectiveness of 

such rule or action. This action 

approving the Indiana, PA attainment 

plan for the 2010 1-hour SO2 NAAQS 

may not be challenged later in 

proceedings to enforce its requirements. 

(See section 307(b)(2).) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Reporting and recordkeeping 

requirements, Sulfur oxides. 

Adam Ortiz, 

Regional Administrator, Region III. 

For the reasons stated in the 

preamble, the EPA amends 40 CFR part 

52 as follows: 

PART 52—APPROVAL AND 

PROMULGATION OF 

IMPLEMENTATION PLANS 

■ 1. The authority citation for part 52 

continues to read as follows: 

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

Subpart NN—Pennsylvania 

■ 2. In § 52.2020: 

■ a. Amend the table in paragraph (d)(3) 

by: 

■ i. Adding entries for ‘‘Keystone 

Generating Station’’, ‘‘Conemaugh 

Generating Station’’, and ‘‘Seward 

Generating Station’’ at the end of the 

table; and 

■ ii. Removing the first entry for 

‘‘Seward Station’’; and the entry for 

‘‘Keystone Plant’’. 

■ b. Adding in paragraph (e)(1) table the 

entry ‘‘Attainment Plan for the Indiana 

County, Pennsylvania Nonattainment 

Area for the 2010 Sulfur Dioxide 

Primary National Ambient Air Quality 

Standard’’ at the end of the table. 

The additions read as follows: 

§ 52.2020 Identification of plan. 

* * * * * 

(d) * * * 

(3) * * * 


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Name of source Permit No. County 

State 

effective 

date 

EPA 

approval date Additional explanation/§ 52.2063 citation 

*******

Keystone Generating Station.Consent Order 

and Agreement.

Armstrong ... 08/15/23 9/13/2024, [INSERT Federal 

Register CITATION].

For Source IDs 031 and 032: Combined 

SO2 emission limit; CEMS monitoring; 

definition of ‘‘24-hour block’’; Quarterly 

emission reporting requirement; and reporting of hourly SO2 lbs/hr emission 

averages. 

Conemaugh Generating Station.Consent Order 

and Agreement.

Indiana ........ 08/15/23 9/13/2024, [INSERT Federal 

Register CITATION].

For Source IDs 031 and 032: Combined 

SO2 emission limit; CEMS monitoring; 

definition of ‘‘3-hour block’’; Quarterly 

emission reporting requirement; and reporting of hourly SO2 lbs/hr emission 

averages. 

Seward Generating Station.Consent Order 

and Agreement.

Indiana ........ 08/17/23 9/13/2024, [INSERT Federal 

Register CITATION].

For Source IDs 034 and 035: Combined 

SO2 emission limit; CEMS monitoring; 

definition of ‘‘operating day’’; reporting of 

hourly SO2 lbs/hr emission rate; injection 

of limestone during initial firing; and quarterly submission of ‘‘Hourly Injection Reports.’’ 

* * * * * 

(e) * * * 

(1) * * * 

Name of non-regulatory SIP revision Applicable geographic area 

State 

submittal 

date 

EPA 

approval date 

Additional 

explanation 

*******

Attainment Plan for the Indiana, 

Pennsylvania Nonattainment Area 

for the 2010 Sulfur Dioxide Primary National Ambient Air Quality 

Standard.

Indiana County and portions of Armstrong County (Plumcreek Township, South Bend Township, and 

Elderton Borough).

10/12/23 9/13/2024, [INSERT Federal ...........

Register CITATION] ........................

52.2033(g). 

* * * * * 

■ 3. Amend § 52.2033 by adding 

paragraph (g) to read as follows: 

§ 52.2033 Control strategy: Sulfur oxides. 

* * * * * 

(g) EPA approves the Attainment Plan 

for the Indiana, PA Nonattainment Area 

for the 2010 Sulfur Dioxide National 

Ambient Air Quality Standard 

submitted by the Pennsylvania 

Department of Environmental Protection 

on October 12, 2023. EPA approves the 

attainment demonstration and other 

attainment plan elements, including 

Reasonably Available Control 

Technology (RACT)/Reasonably 

Available Control Measures (RACM) 

determination, Reasonable Further 

Progress (RFP) requirements, and 

contingency measures. 

[FR Doc. 2024–20598 Filed 9–12–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R04–OAR–2023–0277; FRL–12065– 

02–R4] 

Air Plan Approval; Tennessee; 

Nitrogen Oxides SIP Call Alternative 

Monitoring and Domtar Paper 

Company, LLC 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is approving a State 

Implementation Plan (SIP) revision 

submitted by the State of Tennessee, 

through the Tennessee Department of 

Environment and Conservation (TDEC), 

on June 26, 2023. The June 26, 2023, SIP 

revision specifies monitoring, 

recordkeeping, and reporting 

requirements for large industrial nonelectricity generating units (EGUs) 

subject to the nitrogen oxides (NOX) SIP 

Call that are permissible as alternatives 

to the monitoring, recordkeeping, and 

reporting requirements of 40 CFR part 

75. The SIP revision also establishes 

source-specific alternative monitoring, 

recordkeeping, and reporting 

requirements under the NOX SIP Call for 

Domtar Paper Company, LLC (Domtar). 

DATES: This rule is effective October 15, 

2024. 

ADDRESSES: EPA has established a 

docket for this action under Docket 

Identification No. EPA–R04–OAR– 

2023–0277. All documents in the docket 

are listed on the regulations.gov 

website. Although listed in the index, 

some information may not be publicly 

available, i.e., Confidential Business 

Information or other information whose 

disclosure is restricted by statute. 

Certain other material, such as 

copyrighted material, is not placed on 

the internet and will be publicly 

available only in hard copy form. 

Publicly available docket materials are 

available either electronically through 

www.regulations.gov or in hard copy at 

the Air Regulatory Management Section, 

Air Planning and Implementation 


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