79828 Federal Register / Vol. 89, No. 190 / Tuesday, October 1, 2024 / Proposed Rules 

(F) The only participation in a toxic 

exposure risk activity that is established 

is based on an entry in an exposure 

tracking record system, as defined in 

§ 3.1(cc), that does not corroborate a 

veteran’s potential exposure to toxic 

substances, chemicals, or airborne 

hazards during military service. 

(G) The only participation in a toxic 

exposure risk activity that is established 

is based on an entry in an exposure 

tracking record system, as defined in 

§ 3.1(cc), that is based on the veteran’s 

report of exposure to toxic substances, 

chemicals, or airborne hazards that 

cannot be substantiated. 

* * * * * 

■ 4. Amend § 3.317 by revising the 

section heading and paragraphs (a)(1), 

(c)(3)(ii), and (e)(1) to read as follows: 

§ 3.317 Presumption of service connection 

for certain undiagnosed illnesses and 

medically unexplained chronic multisymptom illnesses occurring in Persian 

Gulf veterans. 

(a) * * * 

(1) Except as provided in paragraph 

(a)(7) of this section, VA will pay 

compensation in accordance with 38 

U.S.C. chapter 11, to a Persian Gulf 

veteran who exhibits objective 

indications of a qualifying chronic 

disability that became manifest to any 

degree at any time, provided that such 

disability, by history, physical 

examination, and laboratory tests, 

cannot be attributed to any known 

clinical diagnosis. 

* * * * * 

(c) * * * 

(3) * * * 

(ii) For purposes of this paragraph (c), 

the term qualifying period of service 

means service in the Southwest Asia 

theater of operations during the Gulf 

War or a period of active military, naval, 

or air service on or after September 19, 

2001, in Afghanistan. 

* * * * * 

(e) Service. For purposes of this 

section: 

(1) The term Persian Gulf veteran 

means a veteran who served on active 

military, naval, or air service in the 

Southwest Asia theater of operations, 

Afghanistan, Israel, Egypt, Turkey, 

Syria, or Jordan, during the Persian Gulf 

War. 

* * * * * 

■ 5. Revise § 3.320 to read as follows: 

§ 3.320 Presumptive service connection 

based on exposure to toxic substances, 

chemicals, and airborne hazards. 

(a) Presumption of exposure. A 

covered veteran as defined in paragraph 

(c) of this section, and required by 38 

U.S.C. 1119(b), shall be presumed to 

have been exposed to the following 

toxic substances, chemicals, and 

airborne hazards during such service, 

unless there is affirmative evidence to 

establish that the veteran was not 

exposed to any such toxic substances, 

chemicals, and airborne hazards during 

that service. 

(1) Fine particulate matter. 

(2) [Reserved] 

(b) Presumption of service connection. 

Except as provided in paragraph (d) of 

this section, the following diseases 

becoming manifest in a covered veteran, 

as defined in paragraph (c) of this 

section, shall be considered to have 

been incurred in or aggravated during 

active military, naval, air, or space 

service, notwithstanding that there is no 

record of evidence of such disease 

during the period of such service. 

(1) Asthma. 

(2) Head cancer of any type. 

(3) Neck cancer of any type. 

(4) Respiratory cancer of any type. 

(5) Gastrointestinal cancer of any 

type. 

(6) Reproductive cancer of any type. 

(7) Lymphoma cancer of any type. 

(8) Kidney cancer. 

(9) Brain cancer. 

(10) Melanoma. 

(11) Pancreatic cancer. 

(12) Chronic bronchitis. 

(13) Chronic obstructive pulmonary 

disease. 

(14) Constrictive bronchiolitis or 

obliterative bronchiolitis. 

(15) Emphysema. 

(16) Granulomatous disease. 

(17) Interstitial lung disease. 

(18) Pleuritis. 

(19) Pulmonary fibrosis. 

(20) Sarcoidosis. 

(21) Chronic sinusitis. 

(22) Chronic rhinitis. 

(23) Glioblastoma. 

(c) Covered veteran. For purposes of 

this section, the term covered veteran 

means any veteran who: 

(1) On or after August 2, 1990, 

performed active military, naval, air, or 

space service while assigned to a duty 

station in, including airspace above: 

(i) The Southwest Asia theater of 

operations as defined in § 3.317(e)(2); or 

(ii) Somalia; or 

(2) On or after September 11, 2001, 

performed active military, naval, air, or 

space service while assigned to a duty 

station in, including airspace above: 

(i) Afghanistan; 

(ii) Djibouti; 

(iii) Egypt; 

(iv) Jordan; 

(v) Lebanon; 

(vi) Syria; 

(vii) Yemen; or 

(viii) Uzbekistan. 

(d) Exceptions. A disease listed in 

paragraph (b) of this section shall not be 

presumed service connected if there is 

affirmative evidence that: 

(1) The disease was not incurred or 

aggravated during active military, naval, 

air, or space service; or 

(2) The disease was caused by a 

supervening condition or event that 

occurred between the veteran’s most 

recent departure from active military, 

naval, air, or space service and the onset 

of the disease; or 

(3) The disease is the result of the 

veteran’s own willful misconduct. 

(e) Special applicability date 

provision. The Secretary has determined 

that all veterans presenting a claim for 

disability compensation for which 

service connection could be established 

based on the presumptions in section 

406 of Public Law 117–168 are ‘‘capable 

of demonstrating other sufficient 

cause,’’ entitling those veterans to an 

applicability date for the presumptions 

concurrent with the date of enactment 

of Public Law 117–168. 

(Authority: 38 U.S.C. 501, 1119, 1120) 

[FR Doc. 2024–21852 Filed 9–30–24; 8:45 am] 

BILLING CODE 8320–01–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R02–OAR–2024–0083; FRL–11767– 

01–R2] 

Finding of Failure To Attain the 

Primary 2010 1-Hour Sulfur Dioxide 

Standard for the San Juan and 

Guayama-Salinas Nonattainment 

Areas; Approval and Conditional 

Approval of Air Quality State 

Implementation Plans; Puerto Rico; 

Attainment Plan for the 2010 1-Hour 

Sulfur Dioxide Standard for the San 

Juan and Guayama-Salinas 

Nonattainment Areas 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing two actions 

related to attainment of the 2010 

primary 1-hour sulfur dioxide (SO2) 

National Ambient Air Quality Standard 

(NAAQS or ‘‘standard’’). First, the EPA 

is proposing to determine that the San 

Juan and Guayama-Salinas SO2

Nonattainment Areas (NAAs) failed to 

attain the 2010 primary 1-hour SO2

NAAQS by the applicable attainment 

date of April 9, 2023, based upon a 

technical analysis of various evidence 


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available (i.e., weight-of-evidence 

analysis). If the EPA finalizes this 

determination as proposed, within one 

year, Puerto Rico will be required to 

submit revisions to the Puerto Rico State 

Implementation Plan (SIP) that, among 

other elements, provide for expeditious 

attainment of the 2010 SO2 standard no 

later than five years from the 

publication date of the final rule. 

Second, the EPA is proposing to 

approve certain elements of Puerto 

Rico’s November 22, 2022, SIP revision 

(hereinafter referred to as the ‘‘plan’’), 

which was submitted to demonstrate 

attainment of the 2010 primary 1-hour 

SO2 standard in the San Juan and 

Guayama-Salinas NAAs. Elements being 

proposed for approval include Puerto 

Rico’s nonattainment new source review 

(NNSR) program and the base year 

emissions inventory. Finally, the EPA is 

proposing to approve in part, and 

conditionally approve in part, for SIPstrengthening purposes, other remaining 

elements of the plan, including 

amendments to Puerto Rico’s Regulation 

for the Control of Atmospheric Pollution 

(or RCAP), which include control 

measures, emissions limitations, and 

reporting requirements for sources in 

the NAAs. 

DATES: 

Comments: Written comments must 

be received on or before December 2, 

2024. 

Public Information Sessions: The EPA 

will hold two public information 

sessions on this proposed rulemaking in 

Puerto Rico on dates and locations to be 

determined and announced at a later 

date. 

For more information on the public 

information sessions, see 

SUPPLEMENTARY INFORMATION. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R02– 

OAR–2024–0083 at https://

www.regulations.gov. Although listed in 

the index, some information is not 

publicly available, e.g., Controlled 

Unclassified Information (CUI) (formally 

referred to as 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 electronically through https:// 

www.regulations.gov. Follow the online 

instructions for submitting comments. 

Once submitted, comments cannot be 

edited or removed from Regulations.gov. 

The EPA may publish any comment 

received to its public docket. Do not 

submit electronically any information 

you consider to be CUI 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. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

submission (i.e., on the web, cloud, or 

other file sharing system). For 

additional submission methods, the full 

EPA public comment policy, 

information about CUI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

Docket: All documents in the 

electronic docket are listed in the 

www.regulations.gov index. Although 

listed in the index, some information is 

not publicly available, i.e., 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. The files will also be made 

available by appointment for public 

inspection between the hours of 9:00 

a.m. and 4:30 p.m. weekdays except for 

legal holidays. Contact the person(s) 

listed in the FOR FURTHER INFORMATION

CONTACT paragraph below to make an 

appointment. If possible, please make 

the appointment at least two working 

days in advance of your visit. We may 

charge you a reasonable fee for copying 

parts of the docket. 

FOR FURTHER INFORMATION CONTACT: 

Nicholas Ferreira, Environmental 

Protection Agency, Region 2, Air 

Programs Branch, 290 Broadway, New 

York, New York 10007–1866, at (212) 

637–3127, or by email at 

ferreira.nicholas@epa.gov, and/or 

Andres Febres, Environmental 

Protection Agency, Region 2, Caribbean 

Environmental Protection Division 

Office, City View Plaza II, #48 RD. 165 

km 1.2, Guaynabo, Puerto Rico, 00968– 

8069, at (787) 977–5801, or by email at 

febres-martinez.andres@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Public Information Session 

The EPA intends to provide two 

public information sessions concerning 

this proposed rule. The EPA will 

announce the date, time, and location 

for each session on its website. These 

public information sessions will provide 

informal opportunities for members of 

the public to learn about this proposed 

action. The EPA anticipates these 

sessions will allow the public to be 

better informed when submitting formal 

comments during the 60-day comment 

period for this proposed action. 

A translator will be present at the 

public engagement sessions to ensure 

participants are able to understand the 

information provided by the EPA. There 

will be no recording or transcript of 

these public information sessions since 

these sessions are not considered to be 

formal public hearings. Statements 

made and/or questions asked at these 

sessions will not be considered formal 

comments on the proposed rule and will 

not be included in the EPA’s response 

to comments, unless submitted as a 

formal comment on the record. 

Members of the public who wish to 

formally comment should do so during 

the 60-day public comment period 

provided following the publication of 

this proposed rule. 

This notice is organized as follows: 

Table of Contents 

I. Background 

A. The 2010 SO2 NAAQS 

B. Designations and Attainment Date 

Requirements for the 2010 SO2 NAAQS 

C. Finding of Failure To Submit and SIP 

Submittal 

D. Puerto Rico’s Integrated Resource Plan 

II. What is the EPA proposing? 

III. Proposed Determination of Failure To 

Attain and the Associated Consequences 

A. Applicable Statutory and Regulatory 

Provisions 

B. San Juan and Guayama-Salinas SO2

Monitoring Networks and Considerations 

C. SO2 Data Considerations and the EPA’s 

Proposed Determination 

1. SO2 Monitor Data 

2. Modeling Data and Control Strategy 

Timeline 

3. Failure To Implement the Control 

Strategy 

4. SO2 Emissions Data 

5. Weight-of-Evidence Analysis 

Conclusions and the EPA’s Proposed 

Determination 

D. Consequences for SO2 NAAs Failing To 

Attain Standards by Attainment Dates 

IV. Requirements for SO2 Nonattainment 

Area Plans 

V. Review of Modeled Attainment 

Demonstration 

A. Modeling Approach 

B. Area of Analysis 

C. Receptor Grid 

D. Meteorological Data 

E. Source Characterization 

F. Emissions Data 

G. Retirements and Emission Limits 

H. Background Concentrations 

I. Summary of Results 

VI. Review of Other Plan Requirements 

A. Emissions Inventory 

B. RACM and RACT and Enforceable 

Emission Limitations and Control 

Measures 

C. New Source Review 

D. Reasonable Further Progress 


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1See 36 FR 8186 (April 30, 1971). 

2See 75 FR 35520 (June 22, 2010), codified at 40 

CFR 50.17(a)–(b). 

3See 83 FR 1101 (Jan. 9, 2018). 

4 83 FR 1098 (Jan. 9, 2018), codified at 40 CFR 

part 81, subpart C. 

5The EPA completed its first round of initial area 

designations for the 2010 1-hour primary SO2

NAAQS effective October 4, 2013. See 78 FR 47191 

(Aug. 5, 2013). A second round of designations was 

effective September 12, 2016, with a supplement 

effective January 17, 2017. See 81 FR 45039 (July 

12, 2016) and 81 FR 89870 (Dec. 13, 2016), 

respectively. A fourth round of designations was 

effective April 30, 2021. See 86 FR 16055 (Mar. 26, 

2021). 

E. Contingency Measures 

F. Conformity 

VII. Puerto Rico’s New Source Review 

Program 

VIII. The EPA’s Evaluation of Rule 425 

IX. Environmental Justice Considerations 

X. The EPA’s Proposed Action 

XI. Incorporation by Reference 

XII. Statutory and Executive Order Reviews 

I. Background 

A. The 2010 SO2 NAAQS 

Under section 109 of the Clean Air 

Act (CAA), the EPA has established 

primary and secondary NAAQS for 

certain pervasive air pollutants (referred 

to as ‘‘criteria pollutants’’) and conducts 

periodic reviews of the NAAQS to 

determine whether they should be 

revised or whether new NAAQS should 

be established. The primary NAAQS 

represent ambient air quality standards 

the attainment and maintenance of 

which the EPA has determined, 

including a margin of safety, are 

requisite to protect the public health. 

The secondary NAAQS represent 

ambient air quality standards the 

attainment and maintenance of which 

the EPA has determined are requisite to 

protect the public welfare from any 

known or anticipated adverse effects 

associated with the presence of such air 

pollutant in the ambient air. 

Under the CAA, the EPA must 

establish NAAQS for criteria pollutants, 

including SO2. SO2 is primarily released 

to the atmosphere through the burning 

of fossil fuels by power plants and other 

industrial facilities. Short-term exposure 

to SO2 can damage the human 

respiratory system and increase 

breathing difficulties. Small children 

and people with respiratory conditions, 

such as asthma, are more sensitive to 

the effects of SO2. Sulfur oxides at high 

concentrations in ambient air can also 

react with compounds to form small 

particulates that can penetrate deeply 

into the lungs and cause health 

problems. 

The EPA first established primary SO2

standards in 1971 at 0.14 parts per 

million (ppm) over a 24-hour averaging 

period and 0.3 ppm over an annual 

averaging period.1 On June 22, 2010, the 

EPA revised the primary NAAQS for 

SO2 and published a new 1-hour 

primary SO2 NAAQS of 75 parts per 

billion (ppb).2 The intent of this 

revision is to provide increased 

protection of public health, providing 

for revocation of the 1971 primary 

annual and 24-hour SO2 standards for 

most areas of the country following area 

designations under the new NAAQS. 

The 2010 standard 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, or 0.075 ppm, as 

determined in accordance with 

Appendix T of 40 CFR part 50.17. The 

EPA established the SO2 NAAQS based 

on significant evidence and numerous 

studies demonstrating that serious 

health effects are associated with shortterm exposures to SO2 emissions 

ranging from five minutes to 24 hours, 

including an array of adverse respiratory 

effects such as narrowing of the airways, 

which can cause difficulty breathing 

(bronchoconstriction) and increased 

asthma symptoms. For more 

information regarding the health 

impacts of SO2, please refer to the June 

22, 2010 final rulemaking. See 75 FR 

35520, codified at 40 CFR 50.17. 

B. Designations and Attainment Date 

Requirements for the 2010 SO2 NAAQS 

Following promulgation of a new or 

revised NAAQS, the EPA is required by 

the CAA to designate areas throughout 

the United States as attaining or not 

attaining the NAAQS; this designation 

process is described in section 

107(d)(1)–(2) of the CAA. For the 2010 

SO2 NAAQS, the EPA defined a 

nonattainment area (NAA) as an area 

that the EPA determined violates the 

2010 1-hour primary SO2 NAAQS and/ 

or contributes to a violation in a nearby 

area, based on the most recent 3 years 

of air quality monitoring data, 

appropriate dispersion modeling 

analysis, and any other relevant 

information.3

On January 9, 2018, the EPA, as part 

of the third round 4 of area designations 

for the 2010 1-hour primary SO2

NAAQS, designated six areas of the 

country as nonattainment, including the 

San Juan and Guayama-Salinas NAAs.5

These area designations had an effective 

date of April 9, 2018. 

Areas designated nonattainment for 

the SO2 NAAQS are subject to the 

general NAA planning requirements of 

CAA section 172 and to the SO2-specific 

planning requirements of subpart 5 of 

part D of Title I of the CAA (sections 

191 and 192). All components of the 

SO2 part D nonattainment area SIP, 

including the emissions inventory, 

attainment demonstration, reasonably 

available control measures (RACM) and 

reasonably available control technology 

(RACT), enforceable emissions 

limitations and control measures, 

Reasonable Further Progress (RFP) plan, 

nonattainment New Source Review 

(NNSR) program, and contingency 

measures, are due to the EPA within 18 

months of the effective date of 

designation of a nonattainment area 

under CAA section 191. 

Therefore, the nonattainment area 

SIPs for areas designated effective April 

9, 2018, were due on October 9, 2019. 

These SIPs are required to demonstrate 

that their respective areas will attain the 

2010 1-hour primary SO2 NAAQS as 

expeditiously as practicable, but no later 

than five years from the effective date of 

designation, or by April 9, 2023, for the 

San Juan and Guayama-Salinas NAAs. 

C. Finding of Failure To Submit and SIP 

Submittal 

For a number of SO2 NAAs, including 

the San Juan and Guayama-Salinas 

NAAs, the EPA published an action on 

November 3, 2020, effective December 

3, 2020, finding that Puerto Rico and 

other pertinent states had failed to 

submit the required SO2 nonattainment 

plan by the submittal deadline. See 85 

FR 69504. This finding initiated a 

deadline under CAA section 179(a) for 

the potential imposition of two 

sanctions clocks related to new source 

review offsets (i.e., ‘‘2-to-1 offsets’’) and 

highway funding, within 18 and 24 

months of the findings, respectively, 

unless the states and territories subject 

to the finding made the necessary 

complete SIP submittal. Additionally, 

this finding initiated a deadline under 

CAA section 110(c) for the EPA to 

promulgate a Federal Implementation 

Plan (FIP) within two years of the 

finding unless, by that time, the EPA 

had approved the submittal as meeting 

applicable requirements. 

On June 3, 2022, the 2-to-1 offset 

sanctions took effect within the Puerto 

Rico NAAs. Before the highway funding 

sanctions could go into effect within the 

NAAs on December 3, 2022, the Puerto 

Rico Department of Natural and 

Environmental Resources (PRDNER) 

submitted a nonattainment plan for the 

San Juan and Guayama-Salinas NAAs 

(i.e., San Juan and Guayama-Salinas SO2

plan) on November 22, 2022, and the 

EPA deemed the PRDNER’s submittal 

administratively and technically 

complete on December 2, 2022. As a 


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6The RCAP amendments were approved by the 

Secretary of the PRDNER on November 21, 2022, 

and became effective on the same day. 

7Final Resolution and Order on the Puerto Rico 

Electric Power Authority’s Integrated Resource 

Plan, Review of the Puerto Rico Electric Power 

Authority Integrated Resource Plan, Case No. 

CEPR–AP–2018–0001, August 24, 2020 (‘‘Approved 

IRP’’), available at https://energia.pr.gov/wpcontent/uploads/sites/7/2020/08/AP20180001-IRPFinal-Resolution-and-Order.pdf. 

8See https://energia.pr.gov/wp-content/uploads/

sites/7/2015/10/AN-ACT-57-20141.pdf. 

9The October 18, 2022 and November 15, 2022 

letters are available in the docket of this 

rulemaking. 

10On June 22, 2020, LUMA entered into an 

operation and maintenance agreement under which 

it will operate the transmission and distribution 

system previously operated by PREPA. PREPA 

maintains ownership over the transmission and 

distribution system. See https://www.p3.pr.gov/wpcontent/uploads/2020/06/executed-consolidatedom-agreement-td.pdf. 

11See LUMA’s Motion in Compliance with 

Resolution and Order of June 18, 2024, and 

Submitting Second Revised IRP Filing Schedule, 

dated June 28, 2024, at ¶ 18, available at https://

energia.pr.gov/wp-content/uploads/sites/7/2024/07/

20240628-AP20230004-Motion-in-Compliance-withResolution-and-Order-of-June-18-2024-andSubmitting-Second-Revised-IRP-FilingSchedule.pdf. 

12See id. at ¶ 27. 

13See PREB Resolution and Order, dated August 

20, 2024, available at https://energia.pr.gov/wpcontent/uploads/sites/7/2024/08/20240820-AP202

30004-Resolution-and-Order.pdf. 

result of the EPA’s determination, the 2- 

to-1 offset sanctions clock was stopped 

and the highway sanctions never took 

effect, per the EPA’s sanctions 

regulations at 40 CFR 52.31; however, 

this completeness determination did not 

terminate the EPA’s FIP obligation that 

was triggered by the EPA’s November 3, 

2020, Finding of Failure to Submit. 

Within the San Juan and GuayamaSalinas SO2 plan, amendments to Puerto 

Rico’s RCAP were submitted for the 

EPA’s approval. The RCAP amendments 

incorporate the SO2 control measures 

and nonattainment provisions of the 

SO2 plan and would become federally 

enforceable upon final approval by the 

EPA. The RCAP amendments consist of 

revisions to Rule 102, ‘‘Definitions,’’ as 

well as the adoption of Rule 210, ‘‘NonAttainment Provisions,’’ and Rule 425, 

‘‘Provisions for SO2 Non-Attainment 

Areas.’’ 6 The PRDNER’s permitting 

requirements to construct new sources 

or modify major sources of emissions of 

SO2 and other pollutants in NAAs, 

including the San Juan and GuayamaSalinas NAAs, are set forth in the 

revisions to Rule 102, ‘‘Definitions,’’ 

and the recently adopted Rule 210, 

‘‘Nonattainment Provisions.’’ Finally, 

the recently promulgated Rule 425 was 

adopted to include control measures, 

emission limits, test methods and 

procedures, reporting and 

recordkeeping requirements, and 

contingency measures for the San Juan 

and Guayama-Salinas NAAs. 

D. Puerto Rico’s Integrated Resource 

Plan 

The compliance strategy for Puerto 

Rico’s SIP, and the accompanying RCAP 

amendments, were developed based on 

the most recent Integrated Resource 

Plan (IRP) approved by the Puerto Rico 

Energy Bureau (PREB),7 as well as 

additional updates provided by the 

PREB, which considered emission unit 

retirements within the San Juan and 

Guayama-Salinas NAAs following the 

integration of renewable energy sources. 

The IRP is a plan that is required 

under Puerto Rico law, with the purpose 

of providing cost-effective electrical 

power to meet Puerto Rico’s energy 

demand over a twenty-year planning 

period, while considering energy 

conservation, resiliency, reliability, 

efficiency, transparency, and the 

environment. Under Act 57–2014,8 a 

Puerto Rico law known as the Puerto 

Rico Energy Transformation and RELIEF 

Act, the Puerto Rico Electric Power 

Authority (PREPA), or the electric 

utility responsible for the operation of 

the electric power transmission and 

distribution system (currently LUMA 

Energy), is required to prepare an IRP 

for the PREB’s approval, which 

considers reasonable resources to satisfy 

energy demand for up to a twenty-year 

period. Puerto Rico’s electric utility is 

also responsible for updating the plan at 

least every three years to reflect changes 

in energy market conditions, 

regulations, fuel prices, and capital 

costs. Pursuant to Act 57–2014, the 

PREB is responsible for establishing and 

implementing regulations to ensure the 

capacity, reliability, safety, and 

efficiency of Puerto Rico’s electrical 

system. This includes evaluating and 

approving the IRP, overseeing and 

ensuring compliance, and 

implementation. 

On August 24, 2020, the PREB issued 

the IRP Final Order, based on the IRP 

submitted by PREPA. The Approved IRP 

included a Modified Preferred Resource 

Plan (Action Plan) considering specific 

power generation capacity additions 

and retirements. In the Approved IRP, 

the PREB established a schedule for 

minimum quantities of renewable 

resources, and battery energy storage 

resources to be procured through the 

Requests for Proposals processes, to be 

completed by June 2023. The Approved 

IRP also directed PREPA to submit a 

renewable resource and battery energy 

storage procurement plan. Specifically, 

the Approved IRP included a program 

for six tranches of procurement for 

renewable energy and battery storage 

resources that would add 3,750 MW of 

renewable sources to the energy grid. 

Based on the procurement of renewable 

resources to be integrated in the Puerto 

Rico Electric System, the Approved IRP 

authorized the retirement of PREPA’s 

older, oil-fired steam resources, 

combined cycle turbines and peaking 

units for the period between 2021 and 

2025. 

The PREB provided an updated 

schedule for emission unit retirements 

and the integration of new renewable 

energy and battery storage resources via 

letter to the PRDNER on October 18, 

2022, which was updated on November 

15, 2022.9 The IRP was scheduled to be 

revised and submitted to the PREB by 

June 28, 2024 by LUMA, the current 

operator of Puerto Rico’s electrical 

power transmission and distribution 

system.10 However, on June 7, 2024, 

LUMA requested that the PREB suspend 

the June 28 deadline, due to modeling 

delays associated with its base case 

scenario.11 LUMA requested that the 

2024 IRP be filed on May 16, 2025, with 

an analysis of four supplemental 

scenarios proposed to be filed on June 

19, 2025.12 On August 20, 2024, the 

PREB denied LUMA’s request for an 

extension, until May 16, 2025, for a full 

IRP. 

The PREB ordered LUMA to file the 

Preferred Resource Plan and ‘‘salient 

components’’ of the base case and 

alternative case scenarios by no later 

than November 29, 2024, and ordered 

LUMA to file certain transmission and 

distribution related requirements by no 

later than February 28, 2025.13

II. What is the EPA proposing? 

The EPA is proposing several actions 

in this rulemaking. First, under CAA 

section 179(c), the EPA is proposing to 

determine that the San Juan and 

Guayama-Salinas SO2 NAAs failed to 

attain the 2010 1-hour primary SO2

standard by the statutory attainment 

date of April 9, 2023. The EPA’s 

proposed Finding of Failure to Attain 

(FFA) determination is based on a 

weight-of-evidence analysis that 

demonstrates that the San Juan and 

Guayama-Salinas areas failed to attain 

the standard by the mandatory 

attainment date. The EPA’s reasoning 

for this decision is described in Section 

III of the preamble. 

Second, the EPA is proposing to 

approve certain elements of Puerto 

Rico’s SO2 plan, which was submitted 

to demonstrate how the San Juan and 

Guayama-Salinas areas would meet the 

2010 1-hour SO2 standard in the San 

Juan and Guayama-Salinas NAAs. The 


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14EPA, Guidance for 1-Hour SO2 Nonattainment 

Area SIP Submissions (April 2014) (‘‘2014 SO2

Guidance’’), 49. 

15 As defined in 40 CFR part 50, Appendix T 

section 1(c), daily maximum 1-hour values refer to 

the maximum 1-hour SO2 concentration values 

measured from midnight to midnight that are used 

in the NAAQS computations. 

16See 40 CFR part 50, Appendix T sections 1(c), 

3(b), 4(c), and 5(a). 

17AQS is the EPA’s repository of ambient air 

quality data. 

18 40 CFR 58.16. 

19 40 CFR 58.15. 

20EPA, Guidance for 1-Hour SO2 Nonattainment 

Area SIP Submissions (April 2014) (‘‘2014 SO2

Guidance’’), p.49, available at https://www.epa.gov/ 

sites/default/files/2016-06/documents/

20140423guidance_nonattainment_sip.pdf. 

21 Id., p.50. 

22See https://www.epa.gov/so2-pollution/

technical-assistance-documents-implementing-2010

-sulfur-dioxide-standard. 

EPA outlines the requirements for 

nonattainment plans under CAA section 

172(c), and reviews Puerto Rico’s plan 

against these requirements in Sections 

IV, V and VI of this preamble. 

Although Puerto Rico submitted its 

plan to satisfy CAA section 172(c) 

requirements, the EPA is proposing to 

approve only specific elements at this 

time for compliance with the CAA. The 

elements being proposed for approval 

include Puerto Rico’s NNSR program 

and base year emissions inventory. The 

EPA is not proposing action on other 

elements of the plan, such as the 

attainment demonstration, RFP, RACM/ 

RACT, emission limitation as necessary 

to provide for NAAQS attainment, and 

contingency measures. The EPA will 

address whether Puerto Rico is meeting 

its statutory obligations for those 

elements in a future rulemaking. 

Finally, amendments to the RCAP, 

which Puerto Rico submitted with the 

plan, are being proposed for approval, 

in part, and conditional approval, in 

part, based on providing SIPstrengthening. 

III. Proposed Determination of Failure 

To Attain and the Associated 

Consequences 

A. Applicable Statutory and Regulatory 

Provisions 

Section 179(c)(1) of the CAA requires 

the EPA to determine whether a NAA 

attained an applicable standard by the 

applicable attainment date based on the 

area’s air quality as of the attainment 

date. In determining the attainment 

status of SO2 NAAs, the EPA may 

consider ambient monitoring data, air 

quality dispersion modeling, and/or a 

demonstration that the control strategy 

in the SIP has been fully 

implemented.14

Under the EPA’s regulations in 40 

CFR 50.17, and in accordance with 40 

CFR part 50 Appendix T, the 2010 1- 

hour annual SO2 standard is met when 

the design value is less than or equal to 

75 ppb. Design values are calculated by 

computing the three-year average of the 

annual 99th percentile daily maximum 

1-hour average concentrations.15 An 

SO2 1-hour primary standard design 

value is valid if it encompasses three 

consecutive calendar years of complete 

data. A year is considered complete 

when all four quarters are complete, and 

a quarter is complete when at least 75 

percent of the sampling days are 

complete. A sampling day is considered 

complete if 75 percent of the hourly 

concentration values are reported; this 

includes data affected by exceptional 

events that have been approved for 

exclusion by the Administrator.16

A determination of whether an area’s 

air quality meets applicable standards is 

generally based upon the most recent 

three calendar years of complete, 

quality-assured data gathered at 

established state and local air 

monitoring stations (SLAMS) in a 

nonattainment area and entered into the 

EPA’s Air Quality System (AQS) 

database.17 Data from ambient air 

monitors operated by state and local 

agencies in compliance with the EPA 

monitoring requirements must be 

submitted to AQS.18 Monitoring 

agencies annually certify that these data 

are accurate to the best of their 

knowledge.19 All certified SO2 air 

monitoring data are used to calculate 

design values that are used to determine 

the area’s air quality status in 

accordance with 40 CFR part 50, 

Appendix T. 

In addition to utilizing ambient 

monitoring data to make determinations 

of attainment by the attainment date, the 

EPA considers air quality dispersion 

modeling and/or a demonstration that 

the control strategy in the SIP has been 

fully implemented. With regard to the 

use of monitoring data for such 

determinations, EPA’s 2014 

Nonattainment SO2 Guidance 20

specifically notes that if the EPA 

determines the air quality monitors 

located in the affected area are located 

in the area of maximum concentration, 

the EPA may be able to use the data 

from these monitors to make the 

determination of attainment without the 

use of air quality modeling data.21 In 

this case, there are SO2 monitors within 

the San Juan and Guayama-Salinas 

NAAs; however, there is no evidence 

indicating that the monitors are located 

within the areas of expected maximum 

concentration. 

Due to insufficient monitoring data 

collected for all three years in the 2020– 

2022 data period for the SO2 monitors, 

the EPA is unable to determine valid 

monitor-based 2020–2022 design values. 

As a result, the EPA has considered 

available air modeling data submitted 

by the PRDNER with its November 22, 

2022, SIP revision, as well as the 

designation modeling the EPA used to 

initially determine that the areas were 

in nonattainment, to assess whether the 

areas attained by the attainment date. 

According to the EPA’s Modeling 

Technical Assistance Document 

(TAD),22 for the purpose of modeling to 

characterize air quality for use in 

designations, the recommended 

approach is to use the most recent 3 

years of actual emissions data and 

concurrent meteorological data. 

However, the TAD also indicates that it 

would be acceptable to use allowable 

emissions in the form of the most 

recently permitted (referred to as PTE or 

allowable) emissions rate that is 

federally enforceable and effective. 

When relying on a modeling 

demonstration based on allowable 

emissions for purposes of determining 

attainment by the attainment date, the 

EPA looks to whether the emission limit 

or limits were adopted and whether the 

relevant source or sources were 

complying with those modeled limits 

prior to the attainment date. That is, 

when determining attainment by the 

attainment date using air quality 

modeling of allowable emissions, the 

EPA looks to whether the state/ 

commonwealth has demonstrated that 

the control strategy in the SIP has been 

fully implemented. This is necessary 

because a modeling demonstration 

based on allowable emissions is not 

itself sufficient since, without the 

supporting emissions information 

reflected in the control strategy, there 

would be no way to confirm that the 

actual emissions were below the 

modeled limits within the period under 

review. 

The EPA would like to clarify that a 

significant amount of information is 

required for the EPA to accurately 

conduct its own air quality dispersion 

modeling to determine attainment by 

the attainment date for these two NAAs. 

This information is not readily 

available, and the limited data currently 

accessible to the Agency raises concerns 

about the reliability of new modeling. 

Specifically, the EPA does not have 

access to fuel use data or concurrent 

meteorological data and continuous 

emissions monitoring systems (CEMS) 

data from the stacks at the PREPA 

facilities (the EPA also believes that 

CEMS provide acceptable historical 


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23A design value is a statistic that describes the 

air quality status of a given location relative to the 

level of the NAAQS. SO2 design values at the 

Bayamo ́n, Catan ̃ o, and Guayama SO2 monitoring 

sites for the 2020–2022 period were obtained from 

the EPA’s Air Quality Design Values web page. See 

https://www.epa.gov/air-trends/air-quality-designvalues#report. 

24Monitoring sites must meet the data 

completeness requirements listed in Appendix T to 

40 CFR part 50 in order to have a valid design 

value. Annual 99th percentile daily maximum 1- 

hour averages with an asterisk (*) indicate that 

those values do not meet these completeness 

requirements. 

emissions information). As a result, it is 

the EPA’s position that any air quality 

dispersion modeling the EPA would 

perform for the purpose of this 

determination would not be 

representative of air quality within the 

areas. Thus, the EPA is not performing 

air quality dispersion modeling to 

support its determination that the areas 

have failed to attain by their attainment 

dates. The EPA will instead consider the 

modeling conducted and provided by 

the PRDNER in its November 22, 2022, 

SIP submission, which shows that 

controls that PRDNER anticipates will 

lead to attainment were not in place 

prior to the areas’ attainment dates. 

As noted earlier in this section, the 

EPA may also consider whether the 

state (or commonwealth) has 

demonstrated that the control strategy in 

the SIP has been fully implemented. 

That said, the PRDNER’s control 

strategy has not been implemented, nor 

has it been approved by the EPA. As a 

result, the EPA cannot determine that 

the subject sources have achieved 

compliance with either the PRDNER’s 

control strategy as submitted to the EPA, 

or a SIP-approved strategy. To address 

this, the EPA is proposing a 

determination that the areas did not 

attain by their attainment date which is 

based on a technical analysis of various 

evidence available (i.e., weight-ofevidence analysis): including the 

control strategy timeline Puerto Rico 

identified and adopted into its RCAP, 

which was determined in coordination 

with the air quality dispersion modeling 

submitted within its November 22, 2022 

SIP revision as well as the EPA’s 

designation modeling; Puerto Rico’s 

failure to implement the control strategy 

in a timely manner thus far; and the 

EPA’s review of annual facility-wide 

emissions data from January 2020 

through December 2022 for the PREPA 

San Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities located within the 

NAAs—as described in Sections III.B 

and III.C of this notice. As noted, the 

determination of whether the monitors 

are located in the area of maximum 

concentration is not needed here, 

because a demonstration is not being 

made that the NAAs have attained the 

2010 SO2 NAAQS by the April 9, 2023 

attainment date. 

B. San Juan and Guayama-Salinas SO2

Monitoring Networks and 

Considerations 

Section 110(a)(2)(B)(i) of the CAA 

requires states to establish and operate 

air monitoring networks to compile data 

on ambient air quality for all criteria 

pollutants. The EPA’s monitoring 

requirements are specified by regulation 

in 40 CFR part 58. These requirements 

are applicable to state, and where 

delegated, local air monitoring agencies 

that operate criteria pollutant monitors. 

The regulations in 40 CFR part 58 

establish specific requirements for 

operating air quality surveillance 

networks to measure ambient 

concentrations of SO2, including 

requirements for measurement methods, 

network design, quality assurance 

procedures, and the minimum number 

of monitoring sites designated as 

SLAMS. 

In sections 4.4 and 4.5 of Appendix D 

to 40 CFR part 58, the EPA specifies the 

minimum requirements for SO2

monitoring sites to be classified as 

SLAMS. SLAMS produce data that are 

eligible for comparison with the 

NAAQS, and therefore, the monitor 

must be an approved federal reference 

method (FRM), federal equivalent 

method (FEM), or approved regional 

method (ARM) monitor, pursuant to 

section 2 of Appendix C to 40 CFR part 

58. Additionally, Appendix A to 40 CFR 

part 58 specifies quality assurance 

requirements for SLAMS monitors. 

During the 2020–2022 data period, the 

PRDNER operated three SO2 SLAMS in 

the San Juan and Guayama-Salinas SO2

NAAs. In the San Juan NAA, SLAMS 

monitors are in operation at Bayamo ́n 

(AQS Site ID 72–021–0010, Avenue 

Central Correcional) and at Catan ̃o (AQS 

Site ID 72–033–0004, Northwest Street 

at the 11 Final Street, Las Vegas). In the 

Guayama-Salinas NAA, a SLAMS 

monitor is located at Guayama (AQS 

Site ID 72–057–0011, Road #3 Cuartel 

Vehiculos Hurtados). 

C. SO2 Data Considerations and the 

EPA’s Proposed Determination 

1. SO2 Monitor Data 

As discussed in Section I.B of this 

preamble, the applicable attainment 

date for the San Juan and GuayamaSalinas areas was April 9, 2023. In 

accordance with Appendix T to 40 CFR 

part 50, determinations of SO2 NAAQS 

compliance are based on three 

consecutive calendar years of data. To 

determine the air quality as of the 

attainment date in the nonattainment 

area, the EPA reviewed the available 

data collected during the three calendar 

years immediately preceding the 

attainment date for the San Juan and 

Guayama-Salinas areas (i.e., January 1, 

2020 through December 31, 2022), as 

well as SO2 emissions data that resulted 

from the burning of fossil fuels for 

electricity generation at the PREPA San 

Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities. 

The available annual 99th percentile 

daily maximum 1-hour average SO2 data 

at each monitoring site within the San 

Juan and Guayama-Salinas areas for the 

2020–2022 period are presented in 

Tables 1 and 2 below. Moreover, the 1- 

hour SO2 design values at the Bayamo ́n, 

Catan ̃ o, and Guayama SO2 monitoring 

sites for the 2020–2022 period are 

shown in Tables 1 and 2 below.23

TABLE 1—2020–2022 SO2 MONITOR DATA FOR THE SAN JUAN AREA 24

SLAMS monitor AQS site ID 

2020 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2021 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2022 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2020–2022 SO2 design 

value 

(ppb) 

Bayamo ́n ............................................................... 72–021–0010 * 35.4 9.8 10.8 Not Valid (NV). 

Catan ̃o .................................................................. 72–033–0004 * 17.6 * 18.2 * 0.0 NV 


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25Monitoring sites must meet the data 

completeness requirements listed in Appendix T to 

40 CFR part 50 in order to have a valid design 

value. Annual 99th percentile daily maximum 1- 

hour averages with an asterisk (*) indicate that 

those values do not meet these completeness 

requirements. 

26The San Juan and Guayama-Salinas areas were 

designated nonattainment based on Puerto Rico’s 

modeling, which indicated that the highest 

predicted 99th percentile daily maximum 1-hour 

concentration (i.e., modeled concentration) within 

the chosen modeling domain to be 422 mg/m3

(equivalent to 161 ppb) for the San Juan area and 

252 mg/m3 (equivalent to 96 ppb) for the GuayamaSalinas area. These modeled concentrations, which 

are above the NAAQS level of 196.4 mg/m3

(equivalent to the 2010 SO2 NAAQS of 75 ppb 

reflecting a 2.619 mg/m3 conversion factor), were 

based on actual emissions from the facilities. The 

TSD for the Round 3 designations is found within 

the docket for this rulemaking. 

TABLE 2—2020–2022 SO2 MONITOR DATA FOR THE GUAYAMA-SALINAS AREA 25

SLAMS monitor AQS site ID 

2020 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2021 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2022 Annual 

99th percentile 

daily maximum 

1-hour 

average 

(ppb) 

2020–2022 

SO2 design 

value 

(ppb) 

Guayama .............................................................................. 72–057–0011 NV * 3.4 * 3.4 NV 

The attainment date for the areas was 

April 9, 2023. In order for the EPA to 

determine that the areas attained by the 

April 9, 2023 attainment date based 

solely on air quality monitoring data, 

the design value based upon complete, 

quality-assured monitored air quality 

data from three consecutive years 

(2020–2022) at each eligible monitoring 

site must be equal to or less than 75 ppb 

for the 1-hour standard, and air quality 

modeling would need to show that there 

was an air quality monitor located in the 

area of maximum concentration. 

The EPA has not been provided with 

nor is the EPA aware of information 

indicating that these three monitors are 

located within the area of maximum 

concentration. Therefore, this 

information alone is insufficient to 

support a determination of whether the 

NAAs attained the 2010 SO2 NAAQS by 

the attainment date. 

2. Modeling Data and Control Strategy 

Timeline 

The EPA’s Modeling TAD notes that 

for area designations under the 2010 

SO2 NAAQS, the American 

Meteorological Society/Environmental 

Protection Agency Regulatory Model 

(AERMOD) modeling system should be 

used, unless use of an alternative model 

can be justified. As previously stated, 

the EPA did not conduct its own air 

dispersion modeling demonstration 

with AERMOD and is instead relying on 

the air dispersion modeling conducted 

by the PRDNER, as provided within its 

attainment demonstration submitted to 

the EPA on November 22, 2022. 

The PRDNER’s attainment 

demonstration utilized version 21112 of 

AERMOD, with default options. Version 

21112 of AERMOD was the most recent 

version at the time the attainment 

demonstration modeling was 

conducted. Further information 

pertaining to the PRDNER’s modeling, 

such as the area of analysis, source 

characterization, emissions, 

meteorology and surface characteristics, 

geography and terrain, and background 

concentrations, can be found in Section 

V, ‘‘Review of Modeled Attainment 

Demonstration,’’ of this proposed 

rulemaking. For purposes of the FFA, 

the EPA finds the PRDNER’s modeling 

was conducted in a technically correct 

manner, consistent with the EPA’s 

modeling guidance. 

The control strategy the PRDNER 

identified and modeled to provide for 

attainment of the standard relies 

primarily on the retirement of PREPA 

electricity generation units and is based 

on the integration of new renewable 

energy projects (as determined by 

PREB). However, this control strategy 

was not scheduled to start until 

February 2023, specifically involving 

the transition of several units to ultralow sulfur diesel fuel. Specifically, the 

retirement of PREPA units was 

scheduled to occur in phases, from June 

30, 2023, through December 31, 2025, at 

PREPA San Juan and PREPA Palo Seco, 

and from December 31, 2025, through 

December 31, 2029, at PREPA Aguirre. 

The projected attainment dates 

identified by the PRDNER, via its 

modeling of the control strategy were 

December 31, 2025, for the San Juan 

area and December 31, 2029, for the 

Guayama-Salinas Area. Although these 

attainment dates for the control strategy 

were identified as being as expeditious 

as practicable given the integration of 

renewable energy sources, they provide 

for attainment of the standard after the 

CAA mandatory attainment date of 

April 9, 2023. Thus, based on the 

PRDNER’s own modeling of its control 

strategy, and unless that control strategy 

was implemented in a more expeditious 

manner than originally planned, the 

control strategy did not provide for 

attainment by the statutory deadline. 

Additionally, the EPA notes that the 

Round 3 designation modeling 26

showed modeled concentrations well in 

exceedance of the standard within the 

San Juan and Guayama-Salinas areas, 

therefore requiring significant measures 

to be implemented to reduce such 

concentrations. Since it is the EPA’s 

understanding that the emissions 

controls necessary to achieve attainment 

of the standard were not implemented 

(as further discussed in Section III.C.3 of 

this notice), the EPA proposes to find 

that attainment of the standard was not 

provided by the mandatory attainment 

date. 

3. Failure To Implement the Control 

Strategy 

As of the time of signature of this 

proposed rulemaking, the EPA has no 

evidence indicating that the control 

strategy identified by the PRDNER and 

adopted within the RCAP in support of 

its November 22, 2022 SIP submission 

has in fact been implemented. Instead, 

available evidence indicates that the 

strategy has not yet been implemented, 

and that therefore, emissions reductions 

expected under the strategy have not yet 

been achieved. Although not federally 

SIP-approved, this absence of strategy 

implementation is considered as part of 

EPA’s weight of evidence analysis. 

The control strategy under the 

PRDNER’s SIP submission is based on 

the retirement of emission units and the 

implementation of emission limits 

based on the use of ULSD or LNG for 

units that will continue to operate and 

generate electricity at the PREPA San 

Juan, PREPA Aguirre, and PREPA Palo 

Seco facilities. As previously noted, the 

control strategy was to begin in 

February 2023, specifically involving 

the transition of several units to ULSD. 

The PREPA unit retirements were to 

occur in phases—from June 30, 2023, 

through December 31, 2025, at PREPA 

San Juan and PREPA Palo Seco, and 

from December 31, 2025, through 

December 31, 2029, at PREPA Aguirre. 

At PREPA Palo Seco and PREPA Palo 

San Juan, several boilers were required 


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27Refer to Table 7. PREPA Aguirre SO2 Emission 

Limits under Section V, ‘‘Review of Modeled 

Attainment Demonstration’’ of this rulemaking for 

more detailed information regarding the specific 

units scheduled to retire from December 31, 2025, 

through December 31, 2029. 

28See Section 6.2, ‘‘Inputs and Assumptions’’ of 

the ‘‘Puerto Rico Grid Resilience and Transitions to 

100% Renewable Energy Study (PR100)’’ provided 

within the docket for this rulemaking. 

29See ¶ 860 of the ‘‘Final Resolution and Order 

on the PREPA’s IRP’’ included within the docket for 

this rulemaking. 

30 Due to the complexity and coordination 

required between stakeholders such as the PREPA, 

the PREB, and LUMA, it is anticipated that a 

revised IRP will not be finalized until late 2026 or 

2027 at this point in time. 

31See ¶ 870–873 of the ‘‘Final Resolution and 

Order on the PREPA’s IRP.’’ 

32 2021 and 2022 data are preliminary and will be 

finalized upon release of the 2023 NEI. The 2023 

NEI inventory year is in progress and will not be 

published until March 2026. See https://

www.epa.gov/air-emissions-inventories/2023- 

national-emissions-inventory-nei-documentation. 

33For more information on EIS, refer to https:// 

www.epa.gov/air-emissions-inventories/emissionsinventory-system-eis-gateway. 

to retire by June 30, 2023. Specifically, 

at PREPA Palo Seco, Boiler 1, Boiler 2, 

Power Block 2–2, Power Block 3–1, and 

Power Block 3–2 had a retirement 

compliance date of June 30, 2023. At 

PREPA San Juan, Boiler 7, Boiler 8, and 

Boiler 10 were required to retire by June 

30, 2023. Additional retirements are 

required at PREPA Palo Seco by 

December 31, 2025 (i.e., Boiler 4), and 

PREPA San Juan by December 31, 2024 

(i.e., Boiler 9). PREPA Aguirre units are 

scheduled to retire beginning December 

31, 2025, through December 31, 2029.27

A more detailed discussion of the 

retirement of emission units and the 

implementation of emission limits for 

units that will remain in operation at 

the PREPA San Juan, PREPA Aguirre, 

and PREPA Palo Seco facilities can be 

found under Section V, ‘‘Review of 

Modeled Attainment Demonstration,’’ 

subsection G, of this proposed 

rulemaking. 

As mentioned previously in Section I, 

‘‘Background,’’ of this notice, the 

compliance strategy for Puerto Rico’s 

SIP was developed based on the most 

recent IRP approved by the PREB in 

2020, as well as additional updates 

provided by the PREB in 2022, which 

considered emission unit retirements 

within the San Juan and GuayamaSalinas NAAs following the integration 

of renewable energy sources and battery 

storage resources. It is the EPA’s 

understanding that the integration of 

renewable energy sources has been 

delayed, including the deployment of 

solar projects under Tranche 1, due to 

renegotiations and legal challenges 

pertaining to the use of the land 

identified for development.28 Tranche 1 

was expected to provide at least 1,000 

MW solar PV (or energy-equivalent 

other renewables) and at least 500 MW 

(2,000 MWh or equivalent) battery 

energy storage; 29 however, its delayed 

implementation has impacted the 

PREPA’s ability to retire units in 

accordance with the submitted SIP 

control strategy since other means of 

providing electricity to citizens of the 

areas is not sufficient. 

The transition to renewable energy, 

which will allow the retirement of units 

at PREPA San Juan, PREPA Aguirre, and 

PREPA Palo Seco, has an uncertain 

timeline. As indicated previously, the 

IRP was scheduled to be revised and 

submitted to the PREB in June 2024 by 

LUMA, but that process has been 

delayed to November 29, 2024. The EPA 

anticipates that a new IRP 30 will 

provide an updated schedule for 

emission unit retirements and the 

integration of renewable energy. 

Moreover, under the current IRP,31

PREPA will retire units ‘‘based on the 

installation schedule and location of 

new peaking generation, new solar PV, 

and energy storage resources to address 

overall and local resource adequacy.’’ 

Accordingly, the retirement sequence of 

the existing PREPA units is contingent 

on the timing, amount, and location of 

replacement generation, which will 

further complicate Puerto Rico’s ability 

to ensure that retirements of emission 

units occur as provided within its 

submitted control strategy timeline. 

The delay in implementing the 

submitted control strategy and the 

extended timeline and uncertainty for 

transitioning to renewable energy 

projects serve as additional evidence 

that Puerto Rico has not met, and has 

fallen well behind, the statutorily 

required attainment date of April 9, 

2023. Moreover, given that the modeling 

submitted by PRDNER did not 

anticipate the areas would attain the 

NAAQS until well beyond the statutory 

April 9, 2023 attainment date, the EPA 

proposes to find that attainment of the 

standard did not occur by the statutory 

attainment date of April 9, 2023. 

4. SO2 Emissions Data 

The EPA has compiled information 

from its Emission Inventory System 

(EIS) that details total SO2 emissions 

from 2020–2022 across the three PREPA 

facilities.32 The Emissions Inventory 

System (EIS) Gateway was developed to 

provide registered EPA, state, local, and 

Tribal users with access to emissions 

inventory data.33 The EIS helps the EPA 

to build the National Emissions 

Inventory (NEI). Additionally, the EIS 

Gateway allows users to manage their 

profile information to add, view, and 

edit facility inventory information for 

their agency; extract data by running 

reports; and access reporting codes. 

Hourly and monthly data are not 

available in the EIS Gateway, so the EPA 

will utilize annual emissions from 

2020–2022 at the three PREPA facilities 

within the discussion regarding annual 

emission trends in the NAAs since the 

designations. That information is as 

follows: 

TABLE 3—FACILITY-WIDE SO2 EMISSIONS OF POINT SOURCES IN THE NAAS FROM 2020–2022 34

Stationary point source Nonattainment area 

2020 SO2

emissions 

(tons per year) 

2021 SO2

emissions 

(tons per year) 

2022 SO2

emissions 

(tons per year) 

PREPA San Juan ........................................... San Juan ........................................................ 3,257 1,369 2,740 

PREPA Palo Seco .......................................... San Juan ........................................................ 5,272 4,322 4,488 

PREPA Aguirre ............................................... Guayama-Salinas ........................................... 8,829 8,164 5,434 

34 2021 and 2022 data are preliminary and will be finalized upon release of the 2023 NEI. 

The PREPA San Juan facility emitted 

3,257 tons of SO2 in 2020, 1,369 tons of 

SO2 in 2021, and 2,740 tons of SO2 in 

2022. The PREPA Palo Seco facility 

emitted 5,272 tons of SO2 in 2020, 4,322 

tons of SO2 in 2021, and 4,488 tons of 

SO2 in 2022. Finally, the PREPA Aguirre 

facility emitted 8,829 tons of SO2 in 

2020, 8,164 tons of SO2 in 2021, and 

5,434 tons of SO2 in 2022. 


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35Modeling of the 2013–2015 emissions data, 

which showed that the San Juan and GuayamaSalinas areas did not meet the 2010 SO2 NAAQS, 

was a basis for the nonattainment designation. 36The PRDNER’s modeling results under the 

Attainment Demonstration provided in its 

November 22, 2022 SIP submission indicated that 

these emissions would result in a modeled 

concentration of 47.518 mg/m3 for the San Juan 

NAA and 47.191 mg/m3 for the Guayama-Salinas 

NAA. These concentrations are below what would 

be required for the NAAs to attain the 2010 SO2

standard. For additional information on the 

projected emissions at the PREPA facilities, see 

Table 11, ‘‘Projected Stationary Point Source SO2

Emissions for 2019–2029’’ under Section VI, 

subsection A, ‘‘Emissions Inventory,’’ within this 

proposed rulemaking. 

37As discussed within Section V.B., ‘‘Area of 

Analysis,’’ within this notice, based on the 

magnitude of emissions and distance relative to the 

NAAs, the EPA concluded that the smaller and 

more distant sources were adequately represented 

in the monitored ambient background 

concentrations. The EPA concluded that these 

sources were not expected to have their maximum 

impacts in the vicinity of PREPA San Juan, PREPA 

Palo Seco, and PREPA Aguirre. 

TABLE 4—FACILITY-WIDE SO2 EMISSIONS OF POINT SOURCES IN THE NAAS FROM 2013–2015 

Stationary point source Nonattainment area 

2013 SO2

emissions 

(tons per year) 

2014 SO2

emissions 

(tons per year) 

2015 SO2

emissions 

(tons per year) 

PREPA San Juan ........................................... San Juan ........................................................ 5,307 5,135 6,063 

PREPA Palo Seco .......................................... San Juan ........................................................ 5,700 3,128 2,979 

PREPA Aguirre ............................................... Guayama-Salinas ........................................... 9,640 9,261 9,585 

Notably, as provided within the 

Round 3 designations,35 Table 4 

indicates that SO2 emissions were: (1) 

5,307 tons in 2013, 5,135 tons in 2014, 

and 6,063 tons in 2015 for PREPA San 

Juan; (2) 5,700 tons in 2013, 3,128 tons 

in 2014, and 2,979 tons in 2015 for 

PREPA Palo Seco; and (3) 9,640 tons in 

2013, 9,261 tons in 2014, and 9,585 tons 

in 2015 for the PREPA Aguirre facility. 

While there has been a decrease in 

emissions at the PREPA San Juan and 

PREPA Aguirre facilities, it is important 

to note that the thousands of tons of SO2

emitted by these facilities from 2020 to 

2022 are significant. Notably, although 

emissions at PREPA Palo Seco appear to 

have decreased from 2013 through 2015, 

emissions increased at the facility from 

2015 to 2020. It is the EPA’s 

understanding, based on the air quality 

dispersion modeling the PRDNER 

provided in its attainment modeling for 

its SO2 plan, that SO2 emissions from 

the three PREPA facilities would need 

to significantly decrease in order to 

provide for attainment of the SO2

standard. The PRDNER projected that 

SO2 emissions would be 43 tons per 

year (tpy) at PREPA San Juan and 12 tpy 

at PREPA Palo Seco by the PRDNERprojected attainment date of December 

31, 2025, as well as 4 tpy at PREPA 

Aguirre by the PRDNER-projected 

attainment date of December 31, 2029.36

In contrast, the SO2 emissions listed in 

Table 3 are significantly higher than the 

emissions for which the PRDNER 

modeled to provide attainment. Thus, 

since the EPA was unable to conduct its 

own additional air quality dispersion 

modeling, the EPA has no evidence 

indicating that the SO2 emissions at the 

facilities from 2020–2022 would 

provide for attainment of the 2010 1- 

hour primary SO2 NAAQS by the 

statutory attainment date. 

The EPA’s emissions assessment 

focused specifically on the three PREPA 

sources: PREPA San Juan, PREPA Palo 

Seco, and PREPA Aguirre. These 

sources were significantly larger in 

terms of emissions compared to smaller 

and more distant sources like Bacardi, 

Edelcar, and Applied Energy System 

(AES). As a result, the smaller emissions 

from these distant sources were dwarfed 

by the impact of the explicitly modeled 

PREPA sources.37 For example, AES 

emitted 245 tons of SO2 in 2014. The 

EPA’s conclusion was based on this 

consideration, ensuring that the 

emissions assessment accurately 

reflected the most relevant contributors 

to air quality in the vicinity. 

Consequently, the EPA proposes to 

find that emissions from the PREPA San 

Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities continue to be 

significant and provide additional 

evidence that the San Juan and 

Guayama-Salinas areas have not 

attained the 2010 1-hour primary SO2

NAAQS by the statutory attainment date 

of April 9, 2023. 

5. The Weight-of-Evidence Analysis 

Conclusions and the EPA’s Proposed 

Determination 

The determination of failure to attain 

for the San Juan and Guayama-Salinas 

NAAs is based on a control strategy 

timeline that does not provide for 

attainment by the statutorily required 

attainment date, Puerto Rico’s failure to 

implement its adopted control strategy 

in a timely manner, and the EPA’s 

review of annual facility-wide emissions 

data from January 2020 through 

December 2022 for the PREPA San Juan, 

PREPA Palo Seco, and PREPA Aguirre 

facilities. 

As discussed in this notice, Puerto 

Rico’s control strategy is deficient in 

providing for attainment by the 

mandatory attainment date. It provided 

for attainment after the statutory date 

and it failed to practicably account for 

the feasibility of retiring relevant 

emission units, resulting in its failure to 

be timely implemented. The EPA’s 

assessment of the air quality dispersion 

modeling that the PRDNER provided in 

its November 22, 2022 SIP submittal 

provides further support for this 

determination. Moreover, due to its 

inability to obtain valid design values 

from SO2 monitors in the San Juan and 

Guayama-Salinas areas, the EPA did not 

utilize monitoring data as the basis for 

this determination. The EPA obtained 

facility-wide SO2 emissions from 2020– 

2022 at PREPA San Juan, PREPA Palo 

Seco, and PREPA Aguirre. This 

emissions data demonstrates that 

emissions from the three PREPA 

facilities continue to be significant and 

there is no evidence that they provide 

for attainment of the standard. 

The EPA proposes to find that this 

weight-of-evidence analysis is sufficient 

to demonstrate that the San Juan and 

Guayama-Salinas area failed to attain 

the standard by the mandatory 

attainment date. The EPA therefore 

proposes to find under CAA section 

179(c)(1) that the San Juan and 

Guayama-Salinas NAAs failed to attain 

the 1-hour SO2 NAAQS by the required 

attainment date of April 9, 2023. 

D. Consequences for SO2 NAAs Failing 

To Attain Standards by Attainment Date 

The consequences for SO2 NAAs 

failing to attain the standards by the 

applicable attainment date are set forth 

in CAA section 179(d). Under section 

179(d), a state must submit a SIP 

revision for the area meeting the 

requirements of CAA sections 110 and 

172, the latter of which requires, among 

other elements, a demonstration of 

attainment, an NNSR program, the base 

year emissions inventory, the 

requirements for meeting RFP, RACM/ 

RACT, and contingency measures. In 

addition, under CAA section 179(d)(2), 

the SIP revision must include such 

additional measures as the EPA may 

reasonably prescribe, including all 


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38 57 FR 13498 (April 16, 1992). 

39 Id. at 13548–13549, 13567–13568. 

40See https://www.epa.gov/sites/default/files/ 

2016-06/documents/20140423guidance_

nonattainment_sip.pdf. 

41 57 FR at 13567–13568. 

42 2014 SO2 Guidance, at 22–39. 

measures that can be feasibly 

implemented in the area, in light of 

technological achievability, costs, and 

any non-air quality and other air 

quality-related health and 

environmental impacts. 

In this case, the primary sources of 

SO2 emissions in the San Juan and 

Guayama-Salinas NAAs are the PREPA 

San Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities. The EPA anticipates 

that the PRDNER will collect relevant 

information on the control measures 

necessary to achieve attainment by the 

required attainment date, as part of its 

development of the SIP revision 

triggered by a final FFA. The state (or 

commonwealth) is required to submit 

the SIP revision within one year after 

the EPA publishes a final action in the 

Federal Register determining that the 

NAA failed to attain the SO2 NAAQS. 

With this proposed rulemaking, the 

EPA is also proposing to approve certain 

elements of the 2010 SO2 attainment 

plans for the San Juan and GuayamaSalinas NAAs, as submitted on 

November 22, 2022, for compliance 

with the CAA and for SIP-strengthening 

purposes. Specifically, the EPA is 

proposing to approve Puerto Rico’s 

NNSR program and the base year 

emissions inventory for compliance 

with the CAA; as well as proposing to 

approve, in part, and conditionally 

approve, in part, amendments to Puerto 

Rico’s RCAP for SIP-strengthening 

purposes. The EPA will not act on 

Puerto Rico’s previously submitted 

demonstration of attainment, RACM/ 

RACT, RFP, emission limitations as 

necessary to provide for attainment, and 

contingency measures, since these 

elements will be addressed in the 

subsequent submittal as a result of the 

FFA, should it become final. 

Under CAA sections 179(d)(3) and 

172(a)(2), the new attainment date for 

each NAA is the date by which 

attainment can be achieved as 

expeditiously as practicable, but no later 

than five years after the EPA publishes 

a final action in the Federal Register 

determining that the NAA failed to 

attain the SO2 NAAQS by the applicable 

attainment date. 

IV. Requirements for SO2

Nonattainment Area Plans 

Nonattainment plans for SO2 must 

meet the applicable requirements of the 

CAA, specifically CAA sections 110, 

172, 191, and 192. The EPA’s 

regulations governing nonattainment 

SIP submissions are set forth in 40 CFR 

part 51, with specific procedural 

requirements and control strategy 

requirements codified at subparts F and 

G, respectively. Soon after Congress 

enacted the 1990 Amendments to the 

CAA, the EPA issued comprehensive 

guidance on SIP revisions in the 

‘‘General Preamble for the 

Implementation of Title I of the Clean 

Air Act Amendments of 1990’’ 

(‘‘General Preamble’’).38 Among other 

things, the General Preamble addressed 

SO2 SIP submissions and fundamental 

principles for SIP control strategies.39

On April 23, 2014, the EPA issued 

recommended guidance for meeting the 

statutory requirements in SO2 SIP 

submissions in a document entitled, 

‘‘Guidance for 1-Hour SO2

Nonattainment Area SIP Submissions’’ 

(‘‘2014 SO2 Guidance’’).40

In the 2014 SO2 Guidance, the EPA 

described the statutory requirements of 

CAA section 172(c) for a complete 

nonattainment plan, including: an 

accurate emissions inventory of current 

emissions for all sources of SO2 within 

the NAA; an attainment demonstration; 

a demonstration of RFP; implementation 

of RACM (including RACT); new source 

review; enforceable emission limitations 

and control measures; and adequate 

contingency measures for the affected 

area. 

For the EPA to fully approve a SIP 

revision which meets the requirements 

of CAA sections 110, 172, 191, and 192, 

and the EPA’s regulations at 40 CFR part 

51, the plan for an affected area must 

demonstrate to the EPA’s satisfaction 

that each of the aforementioned 

requirements has been met. Under CAA 

section 110(l), the EPA may not approve 

a plan that would interfere with any 

applicable requirement concerning 

NAAQS attainment and RFP, or any 

other applicable requirement. Under 

CAA section 193, no requirement in 

effect (or required to be adopted by an 

order, settlement, agreement, or plan in 

effect before November 15, 1990) within 

any area that is nonattainment for any 

of the NAAQS may be modified in any 

manner unless it ensures equivalent or 

greater emission reductions of such air 

pollutant. 

Sections 172(c)(1) and 172(c)(6) of the 

CAA direct states and territories with 

areas designated as nonattainment to 

demonstrate that the submitted plan, 

and the emissions limitations and 

control measures in it, provide for 

attainment of the NAAQS. 40 CFR part 

51, subpart G further delineates the 

control strategy requirements that plans 

must meet, and the EPA has long 

required that all SIPs and control 

strategies reflect four fundamental 

principles of quantification, 

enforceability, replicability, and 

accountability.41 SO2 nonattainment 

plans must consist of two components: 

(1) emission limits and other control 

measures that ensure implementation of 

permanent, enforceable, and necessary 

emission controls, and (2) a modeling 

analysis that 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 no 

later than the attainment date for the 

affected area. In cases where the 

necessary emission limits have not 

previously been made a part of the 

state’s SIP or have not otherwise become 

federally enforceable, the plan must 

include the necessary enforceable limits 

in an adopted form suitable for 

incorporation into the SIP in order for 

the plan to be approved by the EPA. 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 (i.e., specifying clear, 

unambiguous, and measurable 

requirements for which compliance can 

be practicably determined), replicable 

(i.e., the procedures for determining 

compliance are sufficiently specific and 

objective so that two independent 

entities applying the procedures would 

obtain the same result), and accountable 

(i.e., source-specific limits must be 

permanent and must reflect the 

assumptions used in the SIP 

demonstrations). 

The EPA’s 2014 SO2 Guidance 

recommends that emission limits be 

expressed as short-term average limits 

not to exceed the averaging time for the 

applicable NAAQS that the limit is 

intended to help maintain (e.g., 

addressing emissions averaged over one 

or three hours), but it also describes the 

option to utilize emission limits with 

longer averaging times of up to 30 days, 

so long as the state/commonwealth 

meets various suggested criteria.42 The 

2014 SO2 Guidance recommends that, 

should states/territories and sources 

utilize longer averaging times (such as 

30 days), the longer-term average limit 

should be set at an adjusted level that 

reflects a stringency comparable to the 

1-hour average limit at the critical 

emission value shown to provide 


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43 82 FR 46434 (Oct. 5, 2017). 

44 84 FR 29456 (June 24, 2019). 

45 82 FR 45242 (Sept. 28, 2017). 

46The EPA published revisions to Appendix W 

on January 17, 2017, 82 FR 5182. 

47 40 CFR 51.112(a)(1). 

48 40 CFR 51.112(a)(2); Appendix W, section 3.2. 

49See https://www.epa.gov/scram/air-qualitydispersion-modeling-preferred-and-recommendedmodels#aermod. 

50See ‘‘Applicability of Appendix W Modeling 

Guidance for the 1-hr SO2 National Ambient Air 

Quality Standard’’ (August 23, 2010), available at 

https://www3.epa.gov/ttn/naaqs/aqmguide/ 

collection/cp2/20100823_page_1-hr_so2_naaqs_

psd_program.pdf. 

attainment. Additional discussion of 

EPA’s rationale for approving longerterm average limits in selected cases has 

been provided in several notices of 

proposed rulemaking. Examples include 

the Pekin, Illinois area,43 the 

Steubenville, Ohio-West Virginia area,44

and the Central New Hampshire area.45

Preferred air quality models for use in 

regulatory applications are described in 

Appendix A of the EPA’s ‘‘Guideline on 

Air Quality Models’’ (40 CFR part 51, 

Appendix W (‘‘Appendix W’’)).46 In 

general, nonattainment SIP submissions 

must demonstrate the adequacy of the 

selected control strategy using the 

applicable air quality model designated 

in Appendix W.47 However, where an 

air quality model specified in Appendix 

W is inappropriate for the particular 

application, the model may be modified 

or another model substituted, if the EPA 

approves of the modification or 

substitution.48 In 2005, the EPA 

promulgated the American 

Meteorological Society/Environmental 

Protection Agency Regulatory Model 

(AERMOD 49) as the Agency’s preferred 

near-field dispersion model for a wide 

range of regulatory applications 

addressing stationary sources (e.g., in 

estimating SO2 concentrations) in all 

types of terrain based on an extensive 

developmental and performance 

evaluation. Supplemental guidance on 

modeling for purposes of demonstrating 

attainment of the SO2 standard is 

provided in Appendix A of the 2014 

SO2 Guidance. 

Appendix A of the April 23, 2014, 

Guidance for 1-Hour SO2

Nonattainment Area SIP Submissions 

provides extensive guidance on the 

modeling domain, the source inputs, 

assorted types of meteorological data, 

and background concentrations. 

Consistency with the recommendations 

in the 2014 SO2 Guidance is generally 

necessary for the attainment 

demonstration to offer adequately 

reliable assurance that the plan provides 

for attainment. 

As stated previously, attainment 

demonstrations for the 2010 1-hour 

primary SO2 NAAQS must demonstrate 

future attainment and maintenance of 

the NAAQS in the entire area 

designated as nonattainment (i.e., not 

just at the violating monitor) by using 

air quality dispersion modeling (see 

Appendix W) to show that the mix of 

sources and enforceable control 

measures and emission rates in an 

identified area will not lead to a 

violation of the SO2 NAAQS. For the 

short-term (i.e., 1-hour) standard, the 

EPA believes that dispersion modeling, 

using allowable emissions and 

addressing stationary sources in the 

affected area (and in some cases those 

sources located outside the NAA that 

may affect attainment in the area) is 

technically appropriate. This approach 

is also efficient and effective in 

demonstrating attainment in NAAs 

because it takes into consideration 

combinations of meteorological and 

source operating conditions that may 

contribute to peak ground-level 

concentrations of SO2. 

The meteorological data used in the 

analysis should generally be processed 

with the most recent version of 

AERMET, which is the meteorological 

data preprocessor for AERMOD. 

Estimated concentrations should 

include ambient background 

concentrations, follow the form of the 

standard, and be calculated as described 

in the EPA’s August 23, 2010 

clarification memorandum.50

V. Review of Modeled Attainment 

Demonstration 

The EPA is not at this time proposing 

action on the attainment demonstration 

submitted by the PRDNER that aims to 

provide for attainment of the 2010 SO2

NAAQS. However, the following 

discussion addresses various features of 

the modeling that the PRDNER used in 

its submitted attainment demonstration 

for the San Juan and Guayama-Salinas 

NAAs. This discussion may be useful 

for the PRDNER as it continues its 

efforts. Additionally, the modeling was 

considered by the EPA in part of the 

weight-of-evidence analysis for the FFA. 

The EPA anticipates acting on an 

updated attainment demonstration in a 

future SIP submission. 

A. Modeling Approach 

The PRDNER’s submitted attainment 

demonstration utilized the EPA’s 

preferred model, version 21112 of 

AERMOD, with default options. Version 

21112 of AERMOD was the most recent 

version at the time the attainment 

demonstration modeling was 

conducted; however, since then, version 

23132 of AERMOD has become the 

regulatory model version. There were no 

updates from version 21112 to version 

23132 that would significantly affect the 

SO2 concentrations predicted here. 

Therefore, for its own purposes, the EPA 

does not consider the model selection to 

have been inappropriate. However, in a 

future SIP submission, the EPA expects 

that the PRDNER would use the version 

of the model that is current at the time 

of the analysis. 

The PRDNER examined land use 

within three kilometers of the facilities 

in the two NAAs using the Auer 

technique, which is a technique in 

section 7.2.1.1 of Appendix W for 

establishing if an area should be 

modeled as either an urban or rural 

source. It was determined by PRDNER 

that San Juan should be modeled with 

urban dispersion characteristics and 

Guayama-Salinas should be modeled 

with rural dispersion characteristics. 

The EPA has reviewed the maps and 

images provided by the PRDNER and 

expects that it would be reasonable for 

the PRDNER to use these characteristics 

in future modeling. 

B. Area of Analysis 

The PRDNER accounted for SO2

impacts in the modeling domain 

through the inclusion of measured 

background levels and explicitly 

modeled emission sources. In the San 

Juan NAA, the PRDNER included the 

largest SO2 sources in the modeling– 

PREPA San Juan and PREPA Palo Seco. 

The impact from other sources of SO2 in 

the San Juan NAA (contributions from 

Bacardi U.S.A., Inc. (200 PR–165 

Catan ̃ o, 00962), Edelcar Inc. 

(CVMQ+FGQ, Calle B, Guaynabo, 

00965), and other minor and distant 

sources), are included in the 

background monitored concentrations, 

which are added to the concentrations 

from the explicitly modeled sources. In 

the Guayama-Salinas NAA, the PRDNER 

included the largest SO2 source in the 

modeling–PREPA Aguirre (State Road 

No. 3, Int. 705, Salinas, 00751). The 

impact from the other sources of SO2 in 

the Guayama-Salinas NAA (i.e., Applied 

Energy System (AES) Puerto Rico, LP 

(PR–3 Km. 142.0, Jobos Ward, Guayama, 

00784) and other minor and distant 

sources) are included in the background 

monitored concentrations, which are 

also added to the concentration from the 

explicitly modeled sources. 

The PRDNER modeled sources in the 

NAAs (i.e., PREPA San Juan, PREPA 

Palo Seco, and PREPA Aguirre) that 

could cause or contribute to a NAAQS 

violation. The impacts of emissions of 

SO2 from smaller and distant sources 

are represented by background 

monitored concentrations (such as 


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51When considering other sources to include in 

the modeling (other than those that are driving the 

nonattainment), Appendix W in section 8.3.3.b 

states that all sources expected to cause a 

significant concentration gradient in the vicinity of 

the source of interest should be explicitly modeled 

and that the number of such sources is expected to 

be small except in unusual cases. 

52 Data from 2014 was representative of the 

emissions data that was used for the designations 

of the SO2 NAAs in Puerto Rico. Furthermore, the 

PRDNER used 2014 as the base year for emissions 

inventory preparation. The base year inventory 

establishes a baseline that is used to evaluate 

emission reductions achieved by the control 

strategy. 

53See the Technical Support Document, Chapter 

36, Final Round 3 Area designations for the 2010 

1-Hour SO2 Primary National Ambient Air Quality 

Standard for Puerto Rico, available at https://

www.epa.gov/sites/default/files/2017-12/ 

documents/36-pr-so2-rd3-final.pdf. 

54See ‘‘Meteorological Monitoring Guidance for 

Regulatory Modeling Applications’’ (Feb. 2000), 

available at https://www.epa.gov/sites/default/files/ 

2020-10/documents/mmgrma_0.pdf. 

Bacardi, Edelcar, and AES). These 

emissions were dwarfed by emissions 

from the three much larger PREPA 

sources and would not be expected to 

have their maximum impacts in the 

vicinity of the sources of interest.51

However, they may have a smaller 

impact, which is measured at the 

ambient monitor and added to the 

modeled concentration. For instance, 

AES, which is situated in Jobos and 

within close proximity to PREPA 

Aguirre (i.e., less than 5 kilometers 

away), is a relatively small source of 

SO2 emissions when compared to the 

PREPA facility. In 2014,52 AES emitted 

245 tons of SO2, whereas PREPA 

Aguirre released a significantly larger 

amount of 9,261 tons of SO2 during the 

same period. Further, AES is 

approximately 8.5 kilometers east of 

PREPA Aguirre and less than 5 

kilometers upwind of the Guayama 

background monitor. Thus, the AES 

concentration in the area of PREPA 

Aguirre is captured by the measured 

ambient background monitored 

concentration and added to PREPA 

Aguirre’s maximum modeled 

concentration for a total air quality SO2

concentration in the area.53

Based on the magnitude of emissions 

and distance relative to the NAAs, the 

EPA expects that the smaller and more 

distant sources would not have their 

maximum impacts in the vicinity of 

PREPA San Juan, PREPA Palo Seco, and 

PREPA Aguirre. Accordingly, the EPA 

expects that in future modeling, those 

sources could be adequately represented 

in the monitored ambient background 

concentrations, and that the PRDNER’s 

future attainment demonstration could 

account for them in this way. 

Additionally, the EPA believes that the 

background levels could reasonably 

account for other sources influencing air 

quality within the NAAs because data 

used to develop background levels 

include hours during which those 

sources may have impacted the 

monitors. However, the EPA 

acknowledges that conditions pertaining 

to ambient background level 

concentrations of these smaller and 

distant sources could be different in the 

future. 

C. Receptor Grid 

Within AERMOD, air quality 

concentration results are calculated at 

discrete locations identified by the user; 

these locations are called receptors. The 

PRDNER used a coarse grid to determine 

the maximum 1-hour SO2

concentrations and the extent of the 

significant impact area. A denser refined 

grid was placed around the areas of 

maximum 1-hour concentration and 

discrete receptors were placed around 

the facility fence lines. 

For the San Juan NAA, a coarse 

receptor grid with 250-meter spacing 

covers areas with violating receptors 

and the extent of the significant impact 

area. Two refined 50-meter spacing 

receptor grids cover the two areas with 

maximum 1-hour SO2 concentrations 

around PREPA San Juan and PREPA 

Palo Seco. 

For the Guayama-Salinas NAA, a 

coarse grid with 1000-meter spacing 

extending out to 50 kilometers from the 

source is used to determine the 

significant impact area. Two refined 50- 

meter spacing receptor grids cover the 

area with the maximum 1-hour SO2

concentration and another area 

approximately five miles northwest of 

the facility. Beyond the 50-meter refined 

grid around the facility, a 250-meter 

spacing grid is also placed around the 

facility area to ensure that any 

significant concentrations are identified. 

The EPA expects that the receptor 

network could be sufficient to identify 

maximum impacts from all the facilities 

in consideration for characterizing the 

NAAs in the PRDNER’s future 

submission. 

D. Meteorological Data 

The PRDNER utilized onsite 

meteorological data from both the 

PREPA San Juan and PREPA Aguirre 

meteorological stations, which was 

collected and provided by PREPA. The 

PRDNER utilized concurrent Upper Air 

data measured at the San Juan National 

Weather Service located at the San Juan 

Airport. The PRDNER provided 

confirmation that PREPA collected the 

meteorological data and conducted 

quality assurance/quality control (QA/ 

QC) procedures on the data in 

accordance with EPA’s meteorological 

guidance.54 The PRDNER further 

reviewed the data for relevance and 

quality assurance, as per the EPA’s 

guidelines, prior to processing it for use 

within AERMOD. Since there was one 

year that satisfied the EPA’s data 

completeness requirements, the 

PRDNER utilized only one year of 

meteorological data from 2013 for the 

San Juan NAA. In the Guayama-Salinas 

NAA, the PRDNER used three years of 

meteorological data from 2014–2016, 

since multiple years of data were 

available. 

The EPA observed that the 

temperature data at both stations was 

measured at three meters above the 

rooftop and could be possibly 

influenced by other radiation sources. 

The concurrent San Juan National 

Weather Service data was used as a 

substitute only for the temperature data. 

Additionally, since the wind sensor was 

switched during the data collection 

period, the EPA requested that the 

PRDNER perform additional analysis on 

the data collected at PREPA Aguirre. 

The new sensor has a higher wind 

threshold compared to the older sensor. 

The EPA recommended that the 

PRDNER perform two separate AERMET 

runs, one with the older sensor 

threshold and another with the new 

sensor threshold, and then combine the 

files for use in AERMOD. The PRDNER 

followed this recommendation to 

process the data and used it for the 

AERMOD runs for the Guayama-Salinas 

NAA. 

The PRDNER used AERMOD’s 

meteorological data preprocessor 

AERMET (version 21112) with the ADJ_

U* option (with no turbulence data 

included), and Upper Air 

meteorological data from the San Juan 

National Weather Service site, to 

process the data in AERMOD. The 

PRDNER used AERSURFACE (version 

20060) using land cover data from the 

National Land Cover Database 200 

(NLCD 2001) to estimate the surface 

characteristics (albedo, Bowen ratio, and 

surface roughness length). 

E. Source Characterization 

The EPA also reviewed the PRDNER’s 

source characterization in its modeling 

assessment, including source types, use 

of accurate stack parameters, and 

inclusion of building dimensions for 

building downwash. The EPA expects 

that the PRDNER would use these in its 

future submission. 


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55The PREB provided a projected schedule for 

emission unit retirements and the integration of 

new renewable energy and battery storage resources 

via letter to the PRDNER on October 18, 2022, 

which was updated on November 15, 2022. These 

letters are available in the docket of this 

rulemaking. 

56Palo Seco Boiler 2, Power Block 2–2, and 

Power Block 3–2 were permanently shut down and 

out of service on November 9, 2022 (to generate 

netting credits for three MobilePac units in Palo 

Seco). 57The Gas Turbines SJ 5&6 have been operating 

as dual-fuel units since late 2019. The PRDNER 

required the units to switch to ULSD by February 

1, 2023. As of February 1, 2023, the SJ 5&6 emission 

units have been subject to a maximum sulfur 

content of 0.0015% by weight (15 ppm) (which is 

equivalent to an SO2 emission rate of 5.1 lb/hr 

under ULSD firing), as well as a separate SO2 limit 

of 9.8 lb/hr under LNG firing. As listed in Table 2 

above, the PRDNER utilized the more conservative 

rate under LNG firing load for the attainment 

demonstration. More information pertaining to this 

can be reviewed on page 59 of the Modeling 

Protocol included in the docket for this rulemaking. 

F. Emissions Data 

The PRDNER used maximum 

allowable 1-hour emissions from PREPA 

San Juan and PREPA Palo Seco for the 

San Juan NAA, and from PREPA 

Aguirre for the Guayama-Salinas NAA. 

The modeling included the certified SO2

emission rates as provided by PREPA. 

The modeling demonstration considers 

unit retirements at the PREPA facilities 

as discussed in Section V, subsection G 

below. The PRDNER did not include 

start-up and shut-down emissions in the 

modeling due to their infrequent 

occurrence of up to 2–3 times a year. 

G. Retirements and Emission Limits 

The PRDNER’s attainment modeling 

in both the San Juan and GuayamaSalinas NAAs is based on the retirement 

of emission units and the 

implementation of emission limits for 

units that will remain in operation for 

electricity generation at the PREPA San 

Juan, PREPA Aguirre, and PREPA Palo 

Seco facilities through requiring fuel 

switching to ULSD (Ultra Low Sulfur 

Diesel) fuel and LNG (Liquified Natural 

Gas). The PRDNER noted in its SIP 

narrative and Rule 425 of the RCAP that 

the retirement dates for the plan were 

provided by the PREB based on the 

projected integration of renewable 

energy to the generation grid.55 The 

PRDNER noted that this compliance 

strategy is consistent with the existing 

approved IRP, as it considers the 

addition of power generation and 

emission unit retirements within the 

PREPA fleet. 

Table 5 summarizes the SO2 emission 

limits (lb/hr) and/or other requirements, 

including fuel to be fired (0.0015% by 

weight (15 ppm) ULSD) and retirements, 

for emission units at the PREPA Palo 

Seco facility. 

TABLE 5—PREPA PALO SECO SO2

EMISSION LIMITS

Emission unit 

SO2

emission 

limit 

and/or 

other 

requirements 

Compliance 

date 

Boiler 1 .............. Retire .. June 30, 2023 

Boiler 2 56 .......... Retire .. June 30, 2023 

Boiler 3 .............. Retire .. December 31, 

2024 

Boiler 4 .............. Retire .. December 31, 

2025 

Power Block 1– 

1, 1–2.

0.5 lb/ 

hr, 

ULSD.

February 1, 

2023 

Power Block 2–1 0.5 lb/ 

hr, 

ULSD.

February 1, 

2023 

Power Block 2– 

2 61.

Retire .. June 30, 2023 

Power Block 3–1 Retire .. June 30, 2023 

Power Block 3– 

2 61.

Retire .. June 30, 2023 

FT8 MobilePac 1 0.4 lb/ 

hr, 

ULSD.

February 1, 

2023 

FT8 MobilePac 2 0.4 lb/ 

hr, 

ULSD.

February 1, 

2023 

FT8 MobilePac 3 0.4 lb/ 

hr, 

ULSD.

February 1, 

2023 

Table 6 summarizes the SO2 emission 

limits (lb/hr) and/or other requirements, 

including fuel to be fired (0.0015% by 

weight (15 ppm) ULSD and 1 gram/100 

dscf LNG) and retirements, for emission 

units at the PREPA San Juan facility. 

TABLE 6—PREPA SAN JUAN SO2

EMISSION LIMITS

Emission unit 

SO2

emission 

limit and/ 

or other 

requirements 

Compliance 

date 

Gas Turbines 

SJ 5 & 6 57.

9.8 lb/hr, 

ULSD/ 

LNG.

February 1, 

2023 

Boiler 7 ............ Retire .... June 30, 2023 

Boiler 8 ............ Retire .... June 30, 2023 

Boiler 9 ............ Retire .... December 31, 

2024 

Boiler 10 .......... Retire .... June 30, 2023 

Table 7 summarizes the SO2 emission 

limits (lb/hr) and/or other requirements, 

including fuel to be fired (0.0015% by 

weight (15 ppm) ULSD) and retirements, 

for emission units at the PREPA Aguirre 

facility. 

TABLE 7—PREPA AGUIRRE SO2 EMISSION LIMITS

Emission unit SO2 emission limit and/or other requirements Compliance date 

AG1 .................................................................... Retire ................................................................ December 31, 2025 

AG2 .................................................................... Retire ................................................................ December 31, 2026 

Gas Turbine CC1–1HRSG ................................ Retire ................................................................ December 31, 2028 

Gas Turbine CC1–2HRSG ................................ Retire ................................................................ December 31, 2028 

Gas Turbine CC1–3HRSG ................................ Retire ................................................................ December 31, 2028 

Gas Turbine CC1–4HRSG ................................ Retire ................................................................ December 31, 2029 

Gas Turbine CC2–1HRSG ................................ Retire ................................................................ December 31, 2029 

Gas Turbine CC2–3HRSG ................................ Retire ................................................................ December 31, 2029 

As indicated earlier in this section, 

the PRDNER’s control strategy is based 

on the retirement of emission units and 

the implementation of emission limits 

for units that will remain in operation 

at the PREPA San Juan, PREPA Aguirre, 

and PREPA Palo Seco facilities through 

requiring fuel switching to ULSD and 

LNG. There is no intention and/or 

indication of an intention to implement 

longer-term averaging limits within the 

PRDNER’s submission, and therefore, no 


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58Apart from Palo Seco Boiler 2, Power Block 2– 

2, and Power Block 3–2, the EPA is not aware of 

any other retirements that have been made 

according to the proposed schedule in the tables 

herein. 

59This SO2 monitor site closed on January 1, 

2023. 

60CAA section 172(c)(3), 42 U.S.C. 7502(c)(3). 

61 Included in the appendix of the Baseline 

Emission Inventory 2014. 

discussion regarding longer-term 

averaging limits is warranted. 

Rule 425 of the RCAP provides 

requirements for the SO2 plan, 

including providing emission 

reductions through an interim remedy. 

Under the ‘‘Interim Plan,’’ as detailed 

within Sections II, ‘‘Emission 

Limitations for PREPA San Juan and 

PREPA Palo Seco’’ and III, ‘‘Emission 

Limitations for PREPA Aguirre’’ of Rule 

425, certain emission units located at 

the PREPA facilities in Palo Seco, San 

Juan, and Aguirre are prohibited from 

burning any fuel oil above a maximum 

sulfur content of 0.0015 percent by 

weight (15ppm) after February 1, 2023. 

To clarify, while the interim plan 

requiring ULSD provides for significant 

SO2 emission reductions, there is no 

indication that the reductions are 

enough to provide for attainment of the 

NAAQS. 

The PRDNER has provided a schedule 

of retirements for the PREPA steam 

generating units based on the 

integration of renewable energy into the 

system. According to Section II(B) and 

Section III(B) of Rule 425, the emission 

units from the PREPA San Juan, PREPA 

Palo Seco, and PREPA Aguirre facilities 

shall be retired as early as the dates 

provided in tables 5–7 above, unless an 

alternative date is authorized by the 

PREB. This alternative date shall be no 

later than December 31, 2025, for 

PREPA San Juan and Palo Seco, and no 

later than December 31, 2029, for 

PREPA Aguirre.58 If an alternative date 

is requested, PREPA would be required 

to submit to the PRDNER a revision to 

the construction and operation emission 

source permits, a copy of the PREB’s 

alternative retirement date 

authorization, and an explanation for 

the necessity of the alternative date. 

The EPA is not acting on Section II(B) 

and Section III(B) of Rule 425 since the 

EPA anticipates these provisions will be 

revised following the EPA’s final action 

on the FFA, which will require the 

PRDNER to submit a subsequent SIP 

revision. The EPA further evaluates the 

approvability of Rule 425 within 

Section VI of the preamble for this 

notice of proposed rulemaking, entitled, 

‘‘The EPA’s Evaluation of Rule 425.’’ 

H. Background Concentrations 

The PRDNER developed background 

concentrations for the NAAs using 

hourly SO2 measurements from 2007– 

2009 at the Guayama SO2 monitor, Air 

Quality System (AQS) number 72–057– 

0009.59 Other SO2 monitors, such as the 

Catan ̃ o (AQS ID 72–033–0004) or 

Bayamo ́n (AQS ID 72–021–0010) 

monitors, are likely to be impacted by 

the PREPA facilities discussed here. 

This would result in double-counting of 

the impacts from those emissions, since 

the impacts from PREPA are modeled 

and the measured ambient data are 

added to the modeled impacts for a total 

concentration, which is compared to the 

NAAQS. The Guayama monitor is 

representative of the regional 

background and includes impacts from 

natural and man-made sources not 

explicitly included as sources in the 

modeling. The PRDNER used a design 

value from 2007–2009, since the more 

recent monitored data was incomplete 

and did not satisfy the EPA’s data 

completeness requirements. The EPA 

also recommended that for 2007, the 

PRDNER use the maximum daily value 

of 36 ppb, instead of the 99th percentile 

concentration of 6 ppb, since there were 

some missing values in the second 

quarter of 2007. 

I. Summary of Results 

Because a new attainment date will be 

established upon the EPA’s final 

determination that the NAAs failed to 

attain the standard by the mandatory 

attainment date of April 9, 2023, the 

EPA is not proposing action on the 

attainment demonstration portion of the 

PRDNER’s November 2022 SIP 

submission within this rulemaking. 

Instead, the EPA will address the 

PRDNER’s revised attainment 

demonstration following the SIP 

revision the PRDNER will be required to 

submit within 12 months of the EPA 

finalizing its determination that the 

areas failed to attain the standard. 

VI. Review of Other Plan Requirements 

A. Emissions Inventory 

The emissions inventory and source 

emission rate data for an area serve as 

the foundation for air quality modeling 

and other analyses that enable states/ 

territories to: (1) estimate the degree to 

which different sources within a NAA 

contribute to violations within the 

affected area, and (2) assess the 

expected improvement in air quality 

within the NAA as a result of the 

adoption and implementation of control 

measures. The state/commonwealth 

must develop and submit to the EPA a 

comprehensive, accurate, and current 

inventory of actual emissions from all 

sources of SO2 in each NAA, as well as 

any sources located outside the NAA 

that may affect attainment in the area.60

The base year inventory establishes a 

baseline that is used to evaluate 

emission reductions achieved by the 

control strategy and to assess RFP 

requirements. In its submittal, the 

PRDNER used 2014 as the base year for 

emissions inventory preparation. 2014 

data was used as the base year because 

SO2 emissions data from this year was 

the most recently completed emissions 

data available for all sectors in the 

inventory. Data from 2014 was also 

representative of the emissions data that 

was used for the designations of the two 

SO2 NAAs in Puerto Rico, which were 

based on emissions data between 2013 

and 2015. 

The PRDNER considered using 2017 

as an emissions base year; however, it 

was determined that 2017 was not a 

representative year for fuel consumption 

due to the impacts from Hurricanes Irma 

and Maria. These hurricanes caused 

PREPA power plants, which generate 

electricity via the burning of fossil fuels 

and are the principal sources 

contributing to nonattainment in the 

San Juan and Guayama-Salinas areas, to 

be inoperative, or operate at reduced 

capacity, for several months. As a result, 

the PRDNER estimated that electrical 

generation was below fifty percent of 

the normal average in the last quarter of 

2017. 

The PRDNER utilized SO2 actual 

emissions reported for the principal 

stationary point sources in the San Juan 

and Guayama-Salinas NAAs (i.e., 

PREPA San Juan, PREPA Palo Seco, and 

PREPA Aguirre facilities), which were 

submitted under the SIP-approved 

RCAP Rule 410 (Maximum Sulfur 

Content in Fuels), and as a permit 

condition, which requires submission of 

certified annual reports to the PRDNER 

by PREPA. The PRDNER included the 

emissions calculations used to 

determine the actual SO2 emissions 

using reported fuel usage data in its SIP 

submittal.61 The 2014 National 

Emissions Inventory (2014 NEI) was 

used for the other emission inventory 

sectors. 

Table 8 summarizes the 2014 SO2

base year emission inventory by sector 

for the San Juan NAA. 


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TABLE 8—BASE YEAR SO2 EMISSIONS INVENTORY FOR THE SAN JUAN SO2 NAA 

[Tons per year] 

Year Stationary 

point sources 

Stationary 

nonpoint 

sources 

Stationary 

nonpoint 

events 

Fuel 

combustion 

Onroad mobile 

sources 

Nonroad 

mobile 

sources 

2014 ......................................................... 8,262 37 <1 39 33 437 

Table 9 summarizes the 2014 SO2

base year emission inventory by sector 

for the Guayama-Salinas NAA. 

TABLE 9—BASE YEAR SO2 EMISSIONS INVENTORY FOR THE GUAYAMA-SALINAS SO2 NAA 

[Tons per year] 

Year Stationary 

point sources 

Stationary 

nonpoint 

sources 

Stationary 

nonpoint 

events 

Fuel 

combustion 

Onroad mobile 

sources 

Nonroad 

mobile 

sources 

2014 ......................................................... 9,261 4 7 <1 3 <1 

As shown in Tables 8 and 9, the 

majority of SO2 emissions in the 2014 

base year inventory can be attributed to 

the stationary point source category. 

Emissions for this category are provided 

in further detail in Table 10. 

TABLE 10—BASE YEAR STATIONARY POINT SOURCE SO2 EMISSIONS INVENTORY

Stationary point source Nonattainment area Emissions 

(tons per year) 

PREPA Palo Seco ................................................................................................................................... San Juan 3,128 

PREPA San Juan .................................................................................................................................... San Juan 5,135 

PREPA Aguirre ........................................................................................................................................ Guayama-Salinas 9,261 

A projected attainment year emissions 

inventory should also be included in the 

SIP submission, according to the 2014 

SO2 Guidance. This emissions inventory 

should include, in a manner consistent 

with the attainment demonstration, 

estimated emissions for all SO2 sources 

that were determined to have an impact 

on the affected NAA for the projected 

attainment year. 

In addition to the 2014 base year 

inventory of actual emissions, the 

PRDNER’s submission included a 

projected emission inventory for the 

PREPA San Juan, PREPA Palo Seco, and 

PREPA Aguirre facilities that includes 

allowable emissions from 2019 through 

2029. The emissions projections 

represent current permit allowable 

emissions (2019–2022), emissions based 

on an interim remedy relying on the 

mandatory use of ULSD for certain units 

starting in February 2023, and emissions 

that provided for attainment of the 1- 

hour SO2 NAAQS based on their final 

remedy (i.e., emission unit retirements 

and fuel switching to ULSD or LNG 

from 2022–2029). Based on the schedule 

for enforceable retirements, the final 

projected emissions occur through 

December 31, 2025, for PREPA Palo 

Seco and PREPA San Juan, and 

December 31, 2029, for PREPA Aguirre, 

which extends beyond the April 9, 2023 

attainment date. The PRDNER did not 

include an emission inventory for the 

actual 2023 attainment deadline year. 

Table 11 summarizes the PRDNER’s 

projected emissions for the PREPA San 

Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities for 2019–2029. 

TABLE 11—PROJECTED STATIONARY POINT SOURCE SO2 EMISSIONS FOR 2019–2029 

[Tons per year] 

Stationary point source Base potential 

to emit (PTE) 

Interim PTE 

(2023) Final PTE Change (base to final) 

PREPA Palo Seco ........................................................................................... 17,157 11,013 12 ¥17,145 

PREPA San Juan ............................................................................................ 10,215 9,496 43 ¥10,172 

PREPA Aguirre ................................................................................................ 31,246 19,199 4 ¥31,242 

The EPA has evaluated the PRDNER’s 

2014 base year inventory and the 2019– 

2029 projection year inventory. The 

EPA proposes to find the base year 

inventory and the methodologies used 

for its development consistent with the 

EPA’s guidance. As a result, the EPA is 

proposing to determine that the San 

Juan and Guayama-Salinas SO2

nonattainment plan meets the 

requirements of CAA section 172(c)(3) 

for the San Juan and Guayama-Salinas 

SO2 NAAs for its 2014 base year 

inventory. 

As previously stated, the projected 

emissions inventory includes estimated 

emissions for SO2 emission sources for 

a projected attainment year that extends 

beyond the CAA mandatory attainment 

date of April 9, 2023. That said, since 

a new attainment date will be 


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62Rule 425, ‘‘Provisions for SO2 Nonattainment 

Areas,’’ which contains the emission limits and 

other control measures for the PREPA San Juan, 

PREPA Palo Seco, PREPA Aguirre facilities, as well 

as for the San Juan and Guayama-Salinas NAAs, is 

evaluated in Section VI.B of this notice. 63 2014 SO2 Guidance, at 40. 

established following the EPA’s final 

determination that the areas failed to 

attain the standard, the PRDNER will be 

expected to update the projection year 

emissions inventory in its subsequent 

SIP revision. The subsequent SIP 

revision will be required to be 

submitted within 12 months of a final 

determination on the EPA’s proposed 

determination, in accordance with CAA 

section 179(d). Consequently, the EPA is 

not proposing action on the projection 

year emissions inventory in this 

rulemaking. 

B. RACM and RACT and Enforceable 

Emission Limitations and Control 

Measures 

CAA section 172(c)(1) states that 

nonattainment plans should ‘‘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.’’ CAA 

section 172(c)(6) requires plans to 

‘‘include enforceable emissions 

limitations, and such other control 

measures [. . .] as may be necessary or 

appropriate to provide for attainment of 

[the NAAQS].’’ 

The necessary emissions limitations 

or other control measures in the 

PRDNER’s 2022 submitted plan for 

attaining the 1-hour SO2 NAAQS in the 

San Juan and Guayama-Salinas NAAs 

are based on emission unit retirements 

and fuel switching to ULSD. As 

previously mentioned, the enforceable 

control measures established in RCAP 

Rule 425 were to be implemented from 

June 30, 2023, through December 31, 

2025, in the San Juan NAA, and 

December 31, 2025, through December 

31, 2029, in the Guayama-Salinas NAA. 

Rule 425 provides exemptions 

allowing for alternative retirement 

dates, provided they are approved by 

PRDNER and the PREB, but no later 

than December 31, 2025 for the San Juan 

NAA, and December 31, 2029 for the 

Guayama-Salinas NAA. As a result of 

these exemptions, the EPA believes the 

retirement dates listed under Rule 425 

would not provide permanently 

enforceable measures for major sources 

of SO2. The EPA anticipates that the 

PRDNER will remove these exemptions 

within the subsequent SIP revision that 

Puerto Rico will be required to submit 

within one year of the final 

determination of the EPA’s proposed 

finding that the areas failed to attain the 

standard by the statutory attainment 

date. 

Because the San Juan and GuayamaSalinas NAAs will be subject to a new 

attainment date, which will be five 

years following the EPA’s final 

determination that the areas failed to 

attain the standard, the EPA is not 

proposing action on the PRDNER’s 

RACM/RACT and emissions limitations 

or control measures that were submitted 

in accordance with CAA sections 

172(c)(1) and (6). As a result of this new 

attainment date, the EPA expects these 

elements will be revised within the 

subsequent SIP revision that the 

PRDNER will be required to submit 

within one year of the EPA’s final 

finding that the areas failed to attain the 

standard. The EPA will act on these 

elements upon receipt of the PRDNER’s 

subsequent SIP revision. 

C. New Source Review 

Part D of title I of the CAA prescribes 

the procedures and conditions under 

which a new major stationary source or 

major modification may obtain a 

preconstruction permit in an area 

designated nonattainment for any 

criteria pollutant. The nonattainment 

new source review (NNSR) permitting 

requirements in section 172(c)(5) and 

173 of the CAA are among ‘‘the 

requirements of this part’’ to be 

submitted to the EPA as part of a revised 

SIP for a nonattainment area within 18 

months of the effective date of a 

designation or redesignation to 

nonattainment. The NNSR permitting 

requirements provide for the permitting 

of any proposed major stationary source 

of SO2 located in a NAA under the 2010 

SO2 NAAQS. 

The PRDNER submitted its NNSR 

program’s rules for SO2 and other future 

potential nonattainment pollutants in its 

SIP submission to the EPA on November 

22, 2022. Specifically, the PRDNER 

submitted 62 for SIP approval, Rule 102, 

‘‘Definitions,’’ as amended, which 

includes definitions relevant to 

nonattainment; and Rule 210, 

‘‘Nonattainment Provisions,’’ which 

establishes the requirements necessary 

to construct or modify major emission 

sources of SO2 and other pollutants in 

areas designated as NAAs. 

The PRDNER’s NNSR program rules 

are evaluated in Section VII, ‘‘Puerto 

Rico’s New Source Review Program’’ of 

the preamble within this notice of 

proposed rulemaking. These rules 

provide appropriate new source review 

for SO2 sources undergoing construction 

or major modification in the San Juan 

and Guayama-Salinas NAAs, including 

meeting the applicable statutory 

requirements, which include but are not 

limited to the installation of Lowest 

Achievable Emissions Rate (LAER) 

control technology and the acquisition 

of emissions reductions to offset new 

emissions of nonattainment pollutant(s). 

Based on the EPA’s evaluation in 

Section VII, the EPA is proposing, upon 

final approval of the RCAP’s Rules 102 

and 210, that the new source 

requirements have been met for the San 

Juan and Guayama-Salinas NAAs. 

D. Reasonable Further Progress 

The EPA’s policy that Reasonable 

Further Progress (RFP) for SO2 may be 

satisfied by ‘‘adherence to an ambitious 

compliance schedule’’ is based on the 

fact that ‘‘for SO2 there is usually a 

single ‘step’ between pre-control 

nonattainment and post-control 

attainment.’’ 63 Because a new 

attainment date will be promulgated 

upon the EPA’s final determination that 

the NAAs failed to attain the standard 

by the statutory attainment date, and the 

EPA expects this element will be 

revised by the PRDNER with the 

subsequent SIP revision required 

following the EPA’s final determination, 

the EPA is not proposing action on the 

requirements listed under CAA section 

172(c)(2), to provide for RFP toward 

attainment in the San Juan and 

Guayama-Salinas SO2 NAAs. 

E. Contingency Measures 

As discussed in the EPA’s SO2

guidance, section 172(c)(9) of the CAA 

defines contingency measures as 

measures in a SIP that are to be 

implemented in the event an area fails 

to make RFP, or fails to attain the 

NAAQS, by the applicable attainment 

date. Contingency measures are to 

become effective without further action 

by the state/commonwealth or the EPA, 

where the area has failed to (1) achieve 

RFP or (2) attain the NAAQS by the 

statutory attainment date for the affected 

area. These control measures are to 

consist of other available control 

measures that are not included in the 

control strategy for the NAA SIP. The 

EPA’s guidance describes special 

features of SO2 planning that influence 

the suitability of alternative means of 

addressing the requirement in section 

172(c)(9) for contingency measures for 

SO2. Because SO2 control measures are 

by definition based on what are directly 

and quantifiably necessary emissions 


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64See letter dated January 10, 2023, from Richard 

Ruvo, Director, EPA Region II, Air and Radiation 

Division to Anaı ́s Rodrı ́guez Vega, Secretary, Puerto 

Rico Department of Natural and Environmental 

Resources. 

65 40 CFR 93.150 to 93.165. 

controls, any violations of the NAAQS 

are likely related to source violations of 

a source’s permit terms. Therefore, an 

appropriate means of satisfying this 

requirement for SO2 is for a state to have 

a comprehensive enforcement program 

that identifies sources of violations of 

the SO2 NAAQS and to undertake an 

aggressive follow-up for compliance and 

enforcement. 

For its contingency measures 

program, the PRDNER indicated it will 

continue to operate a comprehensive 

program to identify sources violating the 

SO2 NAAQS, and that it will undertake 

compliance inspections and necessary 

enforcement actions. 

In its submission to the EPA, the 

PRDNER clarified that it has authority 

under Article 9(a)(7) of the Puerto Rico 

Energy Public Policy Act (PREPPA) to 

order persons causing or contributing to 

a condition which harms the 

environment and natural resources, or 

which poses an imminent danger for the 

public health and safety, to immediately 

diminish or discontinue their actions. 

Furthermore, the PRNDER indicated 

that Article 9(a)(8) of PREPPA provides 

the PRDNER with the authority to issue 

orders to take the preventative or 

control measures necessary. 

Accordingly, the PRDNER also 

included a provision that, upon 

notification by the PRDNER that a 

nearby monitor has four validated SO2

concentrations in excess of the standard 

or has a monitored SO2 violation based 

on the design value, PREPA would be 

required to undertake a system audit of 

emissions units. Consequently, an audit 

report would be required for submission 

by PREPA to the PRDNER within 90 

days of the notification. An audit report 

would detail the operating parameters of 

all emissions units for four 10-day 

periods up to and including the date 

upon which the reference monitor 

registered each exceedance, together 

with recommended SO2 emission 

control strategies, and evidence that the 

strategies have been deployed, as 

appropriate. Upon receipt of the report, 

the PRDNER would begin a 60-day 

evaluation period to diagnose the 

exceedance, to be followed by a 60-day 

consultation period with PREPA to 

develop and implement necessary 

operational changes. The PRDNER 

indicated that such changes may 

include fuel switching, physical or 

operational reductions, or other changes 

that the PRDNER determined to be 

appropriate. Additionally, if any new 

emission limits were deemed necessary, 

the PRDNER indicated they would be 

submitted to the EPA as a SIP revision. 

The PRDNER has also provided 

details on the corrective actions to occur 

if emission sources do not comply with 

required emission limits and other 

requirements in Section VI of Rule 425. 

Specifically, this includes expedited 

procedures for establishing enforceable 

consent agreements when the adoption 

of revised SIPs is pending, and 

subjecting any source that is found to be 

in violation of an approved compliance 

plan or requirement within such plan to 

repercussions listed under Rule 115. 

Additionally, under Rule 425, the 

PRDNER indicated that if a new 

measure or control was determined to 

be sufficient to address violations of the 

SO2 NAAQS and was promulgated or 

scheduled to be implemented at the 

federal or state level, additional local 

measures might be unnecessary 

following the PRDNER’s submission of 

an analysis to the EPA demonstrating 

that such proposed measures were 

adequate to return an area to attainment. 

Under Rule 425, the PRDNER will also 

have the authority to require any owner 

or operator of an SO2 emissions source 

contributing to air pollution to install, 

operate, and maintain monitoring 

devices; as well as maintain records and 

file periodic reports to the PRDNER. The 

PRDNER will also have the ability under 

Rule 425 to require the submission of an 

‘‘Ambient Air Quality Monitoring Plan’’ 

that complies with the EPA’s guidelines 

and includes an air quality and 

meteorological measurement network 

which collects accurate SO2 air quality 

and meteorology data within the zone 

impacted by SO2 emissions from a 

source. Finally, the PRDNER will have 

authority under Rule 425 to issue 

additional orders which require that a 

previously submitted plan be clarified, 

updated, corrected, supplemented, or 

otherwise amended. 

The PRDNER also provided 

information regarding a proposed 

‘‘Attainment Ambient Monitoring 

Network’’ (or AAMN). The PRDNER 

proposed that the AAMN would 

establish 12 SO2 monitoring stations, 

with six in each of the two 

nonattainment areas. The location of 

these proposed stations would be 

determined based on an analysis that 

predicts the maximum concentrations 

using the EPA-approved AERMOD 

model. Additionally, the PRDNER 

indicated that the proposed SO2

monitoring will be subject to 40 CFR 

part 58 requirements to be used for 

comparison to the NAAQS. The EPA 

did not approve any new SO2 sites as 

part of PRDNER’s 2023 AMNP.64 Based 

on the preliminary information 

provided, the EPA does not believe 

there is sufficient information to 

evaluate the appropriateness of the 

AAMN as part of the contingency 

measures for the plan. 

Although Puerto Rico has taken 

significant steps to develop a 

comprehensive program to satisfy the 

contingency measures requirement for 

SO2, the EPA’s policy is premised on 

full compliance with the approvable 

controls and limits required in the 

approvable plan to ensure attainment. 

However, as previously discussed, the 

EPA is not proposing action on related 

CAA section 172(c) elements of the 

attainment plan, including the 

attainment demonstration, the RFP, and 

the RACM/RACT and enforceable 

emission limitation elements of the SIP, 

because Puerto Rico will be required to 

submit a revised SIP which the EPA 

anticipates will contain an updated 

control strategy based on the new 

attainment date that will be established 

with the EPA’s final determination that 

the areas failed to attain the standard. 

Thus, the EPA is not proposing action 

on the contingency measures the 

PRDNER provided in its submission to 

satisfy section 172(c)(9), because the 

approvability of the contingency 

measures element depends upon the 

approvability of the attainment 

demonstration. 

F. Conformity 

Generally, as set forth in section 

176(c) of the CAA, conformity requires 

that actions by federal agencies do not 

cause new air quality violations, worsen 

existing violations, or delay timely 

attainment of the relevant NAAQS. 

General conformity applies to federal 

actions, other than certain highway and 

transportation projects, if the action 

takes place in a NAA or maintenance 

area (i.e., an area which submitted a 

maintenance plan that meets the 

requirements of section 175A of the 

CAA and has been redesignated to 

attainment) for ozone, particulate 

matter, nitrogen dioxide, carbon 

monoxide, lead, or SO2. The EPA’s 

General Conformity Rule establishes the 

criteria and procedures for determining 

if a federal action conforms to the SIP.65

With respect to the 2010 SO2 NAAQS, 

federal agencies are expected to 

continue to estimate emissions for 

conformity analyses in the same manner 

as they estimated emissions for 

conformity analyses under the previous 

NAAQS for SO2. The EPA’s General 


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66 40 CFR 93.159(b). 

67 Details regarding the EPA’s conditional 

approval and the revisions which the PRDNER has 

committed to make to RCAP Rule 425 by January 

1, 2026, can be found within the commitment letter 

the PRDNER submitted to the EPA on September 2, 

2024, and which the EPA has included within the 

docket for this action. 

68Emission sources are also required to comply 

with provisions provided under Rules 401 through 

421 of the RCAP. 

Conformity Rule includes the basic 

requirement that a federal agency’s 

general conformity analysis be based on 

the latest and most accurate emission 

estimation techniques available.66 When 

updated and improved emission 

estimation techniques become available, 

the EPA expects federal agencies will 

continue to use these techniques to 

ensure projects conform to the SIP. 

The EPA concluded in its 1993 

transportation conformity rule that 

highway and transit vehicles are not 

significant sources of SO2. As a result, 

transportation conformity 

determinations are not required in SO2

nonattainment and maintenance areas. 

Therefore, transportation plans, 

transportation improvement programs, 

and projects are presumed to conform to 

applicable implementation plans for 

SO2. 

VII. Puerto Rico’s New Source Review 

Program 

The PRDNER’s permitting 

requirements for the preconstruction 

review of new major sources in NAAs 

are set forth in the revisions to Rule 102, 

‘‘Definitions,’’ and the newly adopted 

Rule 210, ‘‘Nonattainment Provisions.’’ 

The PRDNER’s NNSR program applies 

to the construction and modification of 

any major stationary source of air 

pollution in a NAA, as required by part 

D of title I of the CAA. To receive 

approval to construct, a source that is 

subject to these regulations must show 

that it will not cause a net increase in 

pollution with more than a 1:1 offset 

ratio, will not create a delay in meeting 

the NAAQS, and will install and use 

control technology that achieves the 

LAER. The revisions to Rule 102 and the 

newly created Rule 210 within the 

RCAP, which the EPA is proposing to 

approve into the SIP, incorporate 

provisions that are consistent with the 

current federal requirements for an 

approvable nonattainment NSR program 

in 40 CFR 51.165. Among these 

provisions is the prohibition of 

construction, unless an effective permit 

is issued that meets the requirements of 

Rule 210, and a certification from the 

applicant that all existing major 

stationary sources owned and operated 

by the applicant in Puerto Rico are 

complying with all applicable emissions 

standards of the CAA or that such 

stationary sources are in compliance 

with an expeditious schedule which is 

federally enforceable or contained in a 

court decree. 

As part of its review of the PRDNER’s 

NNSR submittal, the EPA has 

determined that the revisions are 

consistent with the program 

requirements for the preparation, 

adoption, and submittal of 

implementation plans for NNSR, set 

forth at 40 CFR 51.165. 

VIII. The EPA’s Evaluation of Rule 425 

On November 21, 2022, the PRDNER 

promulgated the new Rule 425, 

‘‘Provisions for SO2 Non-Attainment 

Areas.’’ The new Rule 425 was included 

within the November 22, 2022 SIP 

revision submitted by the PRDNER. 

The EPA is proposing to approve, for 

SIP-strengthening purposes and to make 

federally enforceable, the following 

sections of Rule 425: Section I, 

‘‘Applicability;’’ Section IV, ‘‘Emission 

Limitations for San Juan and GuayamaSalinas Non-Attainment Areas,’’ Section 

V, ‘‘Measurement methods and 

procedures,’’ Subsections (A), (B), and 

(E); and Section VI, ‘‘Contingency 

Measures.’’ Additionally, the EPA is 

proposing to conditionally approve 

Section II, ‘‘Emission Limitations for 

PREPA San Juan and PREPA Palo 

Seco,’’ Subsection (A), Section III, 

‘‘Emission Limitations for PREPA 

Aguirre,’’ Subsection (A), Section V, 

‘‘Measurement methods and 

procedures,’’ Subsections (C), (D), and 

(F). 

Rule 425 is applicable to the current 

and future owners or operators of the 

PREPA San Juan, PREPA Palo Seco, and 

PREPA Aguirre facilities, as indicated 

under Section I, ‘‘Applicability’’ of Rule 

425. Additionally, under Section I of 

Rule 425, any other major sources in or 

nearby the NAAs that have not 

undergone a major modification or 

construction of a new emission unit 

subject to Rule 210 are also subject to 

the provisions of Rule 425. The EPA 

proposes to approve the applicability 

provisions listed under Section I of Rule 

425 for SIP-strengthening purposes. 

Under Section II, ‘‘Emissions 

Limitations for PREPA San Juan and 

PREPA Palo Seco’’ and Section III, 

‘‘Emission Limitations for PREPA 

Aguirre’’ of Rule 425, details are 

provided regarding compliance start 

dates for fuel switching to ULSD of 

certain emission units, retirement 

schedules for emission units not being 

converted to ULSD, and emission limits 

for units using ULSD or LNG at the 

PREPA San Juan, PREPA Palo Seco, and 

PREPA Aguirre facilities. The EPA is 

proposing to conditionally approve the 

ULSD emission limits for units listed 

under Section II(A) and Section III(A) of 

Rule 425, which prevent the burning of 

any fuel oil above a maximum sulfur 

content of 15 ppm at the three 

aforementioned PREPA facilities, since 

fuel switching of emission units to 

ULSD is expected to result in a 

significant decrease of sulfur emissions, 

providing for improved air quality. 

Details regarding the conditional 

approval and revisions the PRDNER has 

committed to make to Rule 425 as 

discussed in its September 2, 2024 

commitment letter 67 are provided in the 

following paragraphs of this section. In 

accordance with section 110(k)(4) of the 

CAA, this proposed conditional 

approval is based on the PRDNER’s 

commitment to make specific revisions 

to Section V of Rule 425, which will 

address concerns the EPA has regarding 

the enforceability of emission limits for 

the specific units listed under Section 

II(A) and Section III(A), and to submit 

such revisions to the EPA by January 1, 

2026 for approval into the SIP for Puerto 

Rico. 

The EPA is not proposing to approve 

and is taking no action on Section II(B) 

and Section III(B) of Rule 425, which 

list the retirement schedules for 

emission units and detail emission 

limits for units at the three PREPA 

facilities, since the EPA anticipates 

these schedules will be revised by 

Puerto Rico to conform with the 

updated control strategy submitted by 

the PRDNER in the subsequent SIP 

submission required under the CAA 

following the EPA’s final determination 

that the areas failed to attain. 

Additionally, the retirement provisions 

within Section II(B) and Section III(B) of 

Rule 425 allow the PRDNER to request 

an alternate date, which provides 

exemptions to a control strategy and are 

therefore not a permanently enforceable 

control strategy. 

In addition, under Section IV, 

‘‘Emission Limitations for San Juan and 

Guayama-Salinas Non-Attainment 

Areas’’ of Rule 425, any emission source 

(or any nearby sources having a 

significant impact) within the 

boundaries of the San Juan and 

Guayama-Salinas NAAs, except for 

PREPA emission units, shall comply 68

with all the provisions within 

subsection IV(A). Thus, no owner or 

operator of any combustion units within 

the boundaries of the NAAs, or nearby 

sources having a significant air quality 

impact on SO2, shall cause or permit the 

burning of any fuel oil above a 

maximum sulfur content of 0.0015 


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69These provisions, which are more fully 

discussed by EPA in Section VI, subsection E of this 

proposed rulemaking, include expedited 

procedures for establishing enforceable consent 

agreements; repercussions for violations; assessing 

new measures; monitoring, reporting, and 

recordkeeping requirements; assessment of 

additional local measures; and the PRDNER’s 

ability to require previously submitted plans to be 

clarified, updated, corrected, supplemented, or 

otherwise amended. 

percent by weight (15 ppm) by no later 

than April 9, 2023 (Sections IV(A)(l)–(2) 

of Rule 425). Under Section IV(B), 

owners or operators of stationary 

sources subject to the limitations of 

Section IV(A) are required to certify in 

writing to the PRDNER that such source 

complies with Rule 425. Finally, under 

Section IV(C), any owner or operator of 

a stationary source subject to the 

limitations of Section IV(A) that cannot 

comply with the emission limits 

established by the date required under 

Rule 425 shall create a compliance plan 

which implements RACT in accordance 

with Rule 205 and in compliance with 

Rule 425. Upon the PRDNER’s approval, 

a compliance plan must then be 

implemented and certified by a 

responsible official for accuracy. The 

EPA is proposing to approve Section IV 

of Rule 425 for SIP-strengthening 

purposes, as it provides for the 

reduction of SO2 emissions within the 

NAAs and provides air quality benefits. 

Regarding the test methods to be 

utilized when determining compliance 

with the allowable emission limits 

listed under Rule 425, the PRDNER 

requires the use of test methods 

provided in 40 CFR part 60. Further 

detail regarding the test methods and 

procedures for PREPA to determine 

compliance with the allowable emission 

limit for any fuel other than coal at the 

PREPA facilities in San Juan, Palo Seco, 

and Aguirre is provided under Section 

V, ‘‘Measurement methods and 

procedures’’ of Rule 425. The EPA 

acknowledges the PRDNER’s 

recommended on-site fuel sampling of 

ULSD (and LNG for PREPA San Juan) in 

accordance with USEPA Method 19, 

ASTM D2622, D4294, D5453, D7039, or 

other appropriate EPA or ASTM 

method. The EPA also acknowledges the 

requirement for the PREPA facilities to 

have monitors recording the amount of 

each fuel type burned at each emission 

unit on an hourly basis and the 

requirement for PREPA to sample each 

batch of fuel prior to use for sulfur 

content (percent by weight), heat value, 

and density. Additional provisions 

under Rule 425 concern sample 

submission for laboratory analysis and 

maintenance of laboratory analysis 

records for a period of at least five years. 

Under this rule, PREPA will also be 

required to maintain monthly records 

listing (a) the fuel used (hourly usage 

and total fuel used for the month), (b) 

sulfur content of the fuel, fuel density, 

fuel heating value, and the basis for the 

sulfur content used (fuel analysis 

showing the date the sample was 

collected, type of fuel, sulfur content, 

and fuel heating value), and (c) SO2

emission rates (lb/hr) with the 

assumption that 100% of the sulfur in 

the fuel is converted to SO2. 

Accordingly, the EPA proposes to 

approve Subsections (A), (B), and (E) of 

Section V under Rule 425 for SIPstrengthening. 

Furthermore, under the current 

Section V of Rule 425, the PREPA San 

Juan, PREPA Palo Seco, and PREPA 

Aguirre facilities (and any owner or 

operator of an SO2 emission source 

subject to Rule 425) will be required to 

retain all data, calculations, and reports 

from any performance test or fuel 

sample developed for the purpose of 

demonstrating compliance with the 

applicable emission limits, emission 

tracking requirements, or emission rate 

limits, for a minimum of five years. 

Additionally, Section V will require that 

these records be made available for 

inspection to the PRDNER upon its 

request. Under Rule 425, the PRDNER 

will also have the authority to issue 

orders to require performance testing, 

fuel sampling, or require record-keeping 

and reporting of emission information. 

The EPA is proposing to conditionally 

approve the reporting provisions under 

Rule 425, Section V, Subsections (C), 

(D), and (F), which only require an 

owner or operator of an SO2 emission 

source in the NAAs to make records 

available for inspection purposes and 

following the PRDNER’s request. 

Section V of Rule 425 includes 

provisions imposing monitoring and 

recordkeeping obligations on the 

relevant sources, such as performance 

and fuel testing, and retention of records 

needed to demonstrate compliance with 

the relevant emission limitations; 

however, the EPA is concerned that the 

absence of periodic reporting 

obligations under Subsections (C), (D), 

and (F) may interfere with enforcement 

of the rule. On September 2, 2024, the 

PRDNER submitted a letter committing 

to revise the reporting provisions under 

Subsections (C), (D), and (F) by January 

1, 2026, which will require facilities 

subject to Rule 425 to submit reports 

semi-annually (i.e., every six months). 

In accordance with section 110(k)(4) of 

the CAA, the EPA may conditionally 

approve a plan based on a commitment 

from a State/commonwealth to adopt 

specific enforceable measures and 

submit the necessary SIP revisions to 

the EPA by a date certain. 

If this conditional approval is 

finalized as proposed, the conditionally 

approved provisions of Rule 425 will 

become part of the SIP and will be 

federally enforceable as of the effective 

date of the final conditional approval. If 

the PRDNER submits the revisions to 

Rule 425 by January 1, 2026, as 

committed to in its September 2, 2024 

commitment letter, the conditionally 

approved provisions will remain a part 

of the SIP unless the EPA disapproves 

the revisions to Rule 425 through 

notice-and-comment rulemaking. If the 

EPA takes final action approving the 

revisions to Rule 425 into the SIP, in the 

same final action, the EPA will also 

convert the conditional approval of Rule 

425, Section V, Subsections (C), (D), and 

(F), to an approval by making 

appropriate revisions to the SIP in the 

Code of Federal Regulations. If the EPA 

disapproves the revisions to Rule 425 

intended to satisfy the PRDNER’s 

commitment, the conditional approval 

will convert to a disapproval, and the 

conditionally approved provisions of 

Rule 425 will no longer be a part of the 

approved SIP for Puerto Rico. 

If the PRDNER fails to meet its 

commitment to submit the necessary 

SIP revisions to the EPA by January 1, 

2026, or if the PRDNER submits timely 

SIP revisions, but the EPA finds the SIP 

submittal to be incomplete, this 

conditional approval will be converted 

to a disapproval. In either case, the EPA 

would notify the PRDNER by letter that 

the conditional approval has converted 

to a disapproval and the EPA would 

subsequently publish a document in the 

Federal Register announcing that the 

conditional approval converted to a 

disapproval. 

As previously stated, the EPA is 

proposing to conditionally approve the 

ULSD emission limits described in 

Section II(A) and Section III(A) of Rule 

425, since the emission limits provide 

for a significant decrease in sulfur 

emissions. The EPA is also proposing to 

conditionally approve the reporting 

provisions which apply to these limits 

described in Section V, Subsections (C), 

(D), and (F). The EPA, however, is not 

conditionally approving these sections 

for compliance with CAA section 172(c) 

requirements. 

Finally, as previously discussed 

under Section VI.E, ‘‘Contingency 

Measures,’’ of this preamble, Section VI, 

‘‘Contingency Measures’’ of Rule 425 

specifies corrective actions 69 to be 

taken if emission sources do not achieve 

compliance with emission limits 


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70See https://screeningtool.geoplatform.gov/en/ 

#3/33.47/-97.5. 

71A census tract is considered disadvantaged if 

it meets the thresholds for at least one of the tool’s 

categories of burden or it is on the lands of a 

federally recognized Tribe. Additional information 

on the categories of burden can be found at https:// 

screeningtool.geoplatform.gov/en/methodology. 

72See https://www.epa.gov/ejscreen. 

73For early applications of EJScreen, the EPA 

identified the 80th percentile filter as the initial 

starting point for the purpose of identifying 

geographic areas that may warrant further 

consideration. In other words, an area with any of 

the 13 EJ Indices at or above the 80th percentile 

nationally should be considered as a potential 

candidate for further review. See https://

www.epa.gov/ejscreen/how-interpret-ejscreen-data. 

74See https://www.epa.gov/system/files/ 

documents/2023-06/ejscreen-tech-doc-version-2- 

2.pdf. 

75 Demographic and socioeconomic data utilized 

within EJS is obtained from the U.S. Census 

Bureau’s American Community Survey (ACS) 

2017–2021 5-Year Estimates. 

76See https://www.epa.gov/system/files/ 

documents/2023-06/ejscreen-tech-doc-version-2- 

2.pdf. 

established in Rule 425 by the dates 

specified. 

Moreover, in Section VI. E of this 

notice of proposed rulemaking, the EPA 

has indicated that the Agency is not 

proposing action on the contingency 

measures within the PRDNER’s plan. 

That is because the EPA’s policy is 

premised on full compliance with 

approvable controls and limits required 

in the approvable plan to ensure 

attainment. However, the EPA 

recognizes that the corrective actions 

outlined in Section VI of Rule 425 will 

have an overall positive impact on air 

quality in the San Juan and GuayamaSalinas NAAs. Therefore, the EPA is 

proposing to approve Section VI of Rule 

425 for SIP strengthening and not to 

satisfy the contingency measure 

requirements of CAA 172(c)(9). 

IX. Environmental Justice 

Considerations 

The PRDNER did not provide any 

information within its November 22, 

2022, SIP submittal to the EPA 

regarding environmental justice (EJ) 

considerations within the two NAAs. 

For informational purposes only, the 

EPA evaluated EJ considerations during 

its review of the PRDNER’s SO2 SIP 

submittal. The EPA did not rely on this 

information to reach any decisions 

described in this action. Notably, the 

CAA and applicable implementing 

regulations neither prohibit nor require 

such evaluation of EJ. The following 

information and discussion is provided 

for informational purposes only. An 

informational application of the White 

House’s Climate and Economic Justice 

Screening Tool (CEJST) 70 produced 

information that indicates that nearly all 

census tracts (or 95% of the population) 

within Puerto Rico are considered 

disadvantaged.71

The evaluation here of environmental 

burdens and susceptible populations is 

based on screening-level analyses 

utilizing version 2.2 of the EPA’s 

Environmental Justice Screening and 

Mapping Tool (EJScreen).72 EJScreen is 

the EPA’s EJ screening and mapping 

tool that provides EPA with a nationally 

consistent dataset and approach for 

combining environmental and 

demographic socioeconomic indicators. 

EJScreen is not a detailed risk analysis 

of EJ issues/concerns; rather, it is a 

screening tool that examines some of the 

relevant issues related to EJ, and there 

is uncertainty in the data included. 

Through its use of EJScreen, the EPA 

determined that there may be potential 

EJ concerns within both SO2 NAAs and 

the areas within a 1-mile radius of the 

three PREPA facilities. The EJScreen 

Community Reports are provided in the 

docket for this action. The results of 

these analyses are being provided for 

informational and transparency 

purposes only. 

In using EJScreen, if any of the EJ 

indices for the areas under 

consideration are at or above the 80th 

percentile nationally, then further 

review may be appropriate.73 Thus, the 

EPA’s discussion of EJScreen results 

will focus on bringing attention to 

indices at or above the 80th percentile. 

As discussed in the EPA’s EJ technical 

guidance,74 people of color and lowincome populations often experience 

greater exposure and disease burdens 

than the general population, which can 

increase their susceptibility to adverse 

health effects from environmental 

stressors. Underserved communities can 

also experience reduced access to health 

care, nutritional, and fitness resources, 

further increasing their susceptibility. 

Furthermore, the EJScreen tool 

provides information on 13 EJ Indices 

and 13 Supplemental Indices. Out of 

these, 11 indices have available data to 

derive in parts of Puerto Rico. Each 

index combines one environmental 

measure with demographic data 75 to 

characterize potential areas of EJ 

concern that may warrant further 

consideration, analysis, or outreach. The 

EJ indices help screen for potential EJ 

concerns and combine data on lowincome and people of color populations 

with a single environmental indicator. 

The supplemental indices offer a 

perspective on community-level 

vulnerability and combine data on 

percent low-income, percent 

linguistically isolated, percent with less 

than a high school education, percent 

unemployed, and low life expectancy 

with a single environmental indicator. It 

is also possible to compare indices for 

a given area to other locations within 

the nation and a State (or 

commonwealth). Specific background 

and source information on these indices 

and environmental indicators can be 

found in the EPA’s ‘‘EJScreen Technical 

Documentation for Version 2.2.’’ 76

The population living within the San 

Juan NAA has high (for the purpose of 

this discussion, at or above the 80th 

percentile) EJ and/or Supplemental 

Index values at the national and/or State 

(or commonwealth) level for 9 of the 11 

indices available in EJScreen. These 

include Diesel Particulate Matter, Toxic 

Releases to Air, Traffic Proximity, Lead 

Paint, Superfund Proximity, RMP 

Facility Proximity, Hazardous Waste 

Proximity, Underground Storage Tanks, 

and Wastewater Discharge. While none 

of these indices have direct implications 

to SO2 emissions, and are not at issue 

in the SIP submission, they highlight 

that there may be some potential EJ 

concerns within the area. 

The population living within the 

Guayama-Salinas NAA also has high 

(for the purpose of this discussion, at or 

above the 80th percentile) EJ and/or 

Supplemental Index values at the 

national and/or State (or 

commonwealth) level for 6 of the 11 

indices available in EJScreen. These 

include Air Toxics Cancer Risk, Toxic 

Releases to Air, Traffic Proximity, Lead 

Paint, Superfund Proximity, and 

Wastewater Discharge. While none of 

these indices have direct implications to 

SO2 emissions, and are not at issue in 

the SIP submission, they highlight that 

there may be some potential EJ concerns 

within the area. 

The EPA elected to conduct further 

analysis of the areas within a 1-mile 

radius of the three PREPA facilities (and 

within the NAAs) to ensure that the 

areas of maximum impact from 

emissions at the PREPA facilities were 

being considered. 

The results in EJScreen for the areas 

within a 1-mile radius of both the 

PREPA San Juan and PREPA Palo Seco 

facilities indicated that the populations 

were in the 96th percentile for People of 

Color nationally (99 percent of the 

population in both of the areas within 

a 1-mile radius are considered People of 

Color). The area within a 1-mile radius 

of the PREPA San Juan facility is in the 

97th percentile nationally for low 

income (81 percent of the population 

within a 1-mile radius of the PREPA San 

Juan facility is considered to be lowincome), and the area within a 1-mile 

radius of the PREPA Palo Seco facility 


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77See https://www.fema.gov/disaster/4339. 

78See Jones, G., The Future of Energy in Puerto 

Rico: Current Challenges and Opportunities for a 

Resilient Power Grid. On Behalf of the U.S. 

Environmental Protection Agency, Region 2 

Brownfields Program (2021/12/15), https://

www.bu.edu/rccp/files/2022/01/Energy-Resiliencein-Puerto-Rico.pdf. 

79See U.S. Energy Information Administration, 

‘‘Puerto Rico, Territory Profile and Energy 

Estimates,’’ available at https://www.eia.gov/state/ 

?sid=RQ#:∼:text=Puerto%20Rico%27s%20reliance

%20on%20petroleum, fired%20power%20plant 

and https://www.eia.gov/electricity/annual/html/ 

epa_02_10.html. 

80See U.S. Energy Information Administration, 

‘‘State Energy Profiles, Puerto Rico,’’ available at 

https://www.eia.gov/beta/states/states/RQ/data. 

81See https://www.epa.gov/diesel-fuel-standards/ 

diesel-fuel-standards-and-rulemakings. 

82See docket for projected SO2 emission 

reductions. 

is in the 76th percentile (46 percent of 

the population within a 1-mile radius of 

the PREPA Palo Seco facility is 

considered to be low-income). The 

population living within a 1-mile radius 

of the PREPA San Juan facility is at or 

above the 90th percentile for EJ and/or 

Supplemental Index values at the 

national and/or State (or 

commonwealth) level for all 11 

available indices in EJScreen. The 

population living within a 1-mile radius 

of the PREPA Palo Seco facility is at or 

above the 80th percentile for EJ and/or 

Supplemental Index values at the 

national/and or State (or 

commonwealth) level for 7 of the 10 

available indices. In addition, the 

population within the Guayama-Salinas 

NAA, and within a 1-mile radius of the 

PREPA Aguirre facility, are both in the 

98th percentile nationally for People of 

Color (with 100 percent of the 

population considered People of Color), 

and in the 96th percentile nationally for 

low-income (with 78 percent of the 

population considered low-income). 

Based on all the screening-level 

demographic and socioeconomic data 

previously detailed, the populations 

within both NAAs and within a 1-mile 

radius of the three PREPA facilities are 

predominately made up of people of 

color and/or low-income individuals. 

As a result, conditions that exist prior 

to this action have the potential to result 

in disproportionate and adverse effects 

on communities with EJ concerns. 

The reliability of Puerto Rico’s energy 

infrastructure has been impacted by a 

combination of factors, including its 

vulnerability to severe storms and an 

aging fossil fuel-reliant generation fleet. 

After Hurricane Maria in 2017, Puerto 

Rican households experienced the 

largest and longest blackout in U.S. 

history, and the second-longest blackout 

in the world, with 80 percent of the 

island’s power lines leveled.77

Moreover, Puerto Rico’s fleet of fossil 

fuel generators is the oldest in the 

United States, with an average age of 44 

years as compared with the national 

average of 18 years.78 Notably, although 

the poverty rate in Puerto Rico is more 

than three times the national average, 

Puerto Ricans pay an average of almost 

twice as much for electricity as U.S. 

mainland customers.79 The average 

price of electricity in 2022 across all 

sectors (residential, commercial, and 

industrial) in Puerto Rico averaged 

29.63 cents/kWh, which is higher than 

every U.S. State except Hawaii (and 

excluding other U.S. Territories).80

The EPA anticipates that its proposed 

conditional approval of the use of ULSD 

at the three PREPA facilities will not 

negatively impact energy reliability for 

citizens within the NAAs. The lower 

sulfur content in ULSD (15 ppm) has the 

potential to reduce harmful emissions 

from nonroad diesel sources by more 

than 90%.81 Thus, the anticipated 

significant reduction in sulfur content, 

compared to the sulfur content of diesel 

fuel previously used at the three PREPA 

facilities, is expected to result in 

approximately 15,000 tons of projected 

SO2 reductions annually that will bring 

the NAAs closer to attainment of the 

NAAQS.82 At a minimum, this action is 

not expected to worsen any existing air 

quality, and the EPA believes that this 

proposed action will provide benefits to 

communities living within the NAAs, as 

it will provide for emission reductions 

along with ensuring the continued 

operation of existing electric generating 

units at the PREPA facilities. 

Public participation and community 

involvement are crucial for ensuring 

that decisions affecting human health 

and the environment advance 

environmental justice considerations. 

Communities affected by environmental 

justice issues often face many 

challenges and barriers associated with 

meaningful involvement and adequate 

representation in the development, 

implementation, and enforcement of 

environmental laws, regulations, and 

policies. Consequently, to provide 

ample time for meaningful involvement, 

the EPA will extend its comment period 

for this notice of proposed rulemaking 

(NPRM) from the customary 30 days to 

60 days. 

Additionally, as previously detailed 

within this NPRM, to provide effective 

and meaningful involvement from 

community members during the 

comment period for this NPRM, the EPA 

will hold public information sessions 

concerning this proposed rulemaking. 

Given the high percentage of 

households whose primary language is 

Spanish, the EPA intends to provide all 

public distributions and supporting and 

related materials for this rulemaking 

that are legally permitted to be 

translated, in both Spanish and English, 

to the best of its ability. A Spanish 

translator will also be present at these 

public information sessions to ensure 

participants are able to understand the 

information provided by the EPA. The 

EPA will announce the date, time, and 

location for each session on its website. 

These sessions will allow citizens an 

opportunity to learn more about this 

proposed action, which will enhance 

their ability to provide more informed 

official comments during the public 

comment period. See the 

Supplementary Information section for 

additional information regarding the 

Public Information Sessions. 

As previously stated, this analysis of 

EJ considerations was done solely for 

the purpose of providing additional 

context and information about this 

proposed rulemaking to the public and 

is not a basis for the action. The EPA is 

taking action under the CAA and on 

bases independent of EJ. 

X. The EPA’s Proposed Action 

First, the EPA proposes, under CAA 

section 179(c)(1), to determine that the 

San Juan and Guayama-Salinas areas 

failed to attain the 2010 1-hour SO2

standard by the statutory attainment 

date of April 9, 2023. This 

determination is based upon a weightof-evidence analysis, including (1) the 

control strategy timeline Puerto Rico 

identified and adopted into its RCAP 

and submitted in support of its air 

quality dispersion modeling of its 

November 22, 2022 SIP revision, which 

did not provide for attainment by the 

statutory attainment date; (2) Puerto 

Rico’s inability to effectively implement 

the control strategy it identified and 

adopted within a timely manner thus 

far; and (3) the EPA’s review of annual 

facility-wide emissions data from 

January 2020 through December 2022 

for the PREPA San Juan, PREPA Palo 

Seco, and PREPA Aguirre facilities 

located within the NAAs. 

If the EPA’s determination is finalized 

as proposed, the Commonwealth of 

Puerto Rico will be required under CAA 

section 179(d) to submit revisions to the 

SIP for the San Juan and GuayamaSalinas SO2 NAAs. The required SIP 

revision for each area must, among other 

elements, demonstrate expeditious 

attainment of the standards within the 

time period prescribed by CAA section 

179(d). If the EPA’s determination is 

finalized as proposed, the SIP revisions 

required under CAA section 179(d) will 

be due for submittal to the EPA no later 


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than one year after the publication date 

of the final action notice. 

Second, the EPA proposes to approve 

certain but not all elements of Puerto 

Rico’s SIP submission, submitted to the 

EPA by the PRDNER on November 22, 

2022. Specifically, the EPA is proposing 

to approve the following elements for 

compliance with the requirements of 

section 172(c) of the CAA: Puerto Rico’s 

NNSR program, the base year emissions 

inventory, and to affirm that the NNSR 

requirements for the NAAs have been 

met. If finalized, this action would 

incorporate RCAP amendments under 

Rules 102 and 210 into Puerto Rico’s 

approved and federally enforceable SIP. 

The EPA is not proposing action on 

other remaining elements within Puerto 

Rico’s November 22, 2022 submission, 

as a result of the anticipated revisions 

to the SIP, which Puerto Rico would be 

required to submit within one year of 

the publication date of the final action 

pursuant to CAA section 179(d), should 

the EPA finalize its determination that 

the areas failed to meet the attainment 

date of April 9, 2023. The EPA is 

therefore not proposing action on the 

PRDNER’s attainment demonstration, 

contingency measures, RACM/RACT 

and emission limitations necessary for 

attainment, as well as the requirements 

for meeting RFP toward attainment of 

the NAAQS. 

Additionally, the EPA proposes to 

approve, in part, and conditionally 

approve, in part, and not for compliance 

with the CAA section 172(c) 

requirements, specific amendments to 

Rule 425 of Puerto Rico’s RCAP, which 

include control measures, emission 

limitations, and reporting requirements 

for sources in the NAAs. Specifically, 

the EPA is proposing to approve for SIPstrengthening, the following sections of 

Rule 425: Section I, ‘‘Applicability;’’ 

Section IV, ‘‘Emission Limitations for 

San Juan and Guayama-Salinas NonAttainment Areas;’’ Section V, 

‘‘Measurement methods and 

procedures,’’ Subsections (A), (B), and 

(E); and Section VI, ‘‘Contingency 

Measures.’’ Moreover, the EPA is 

proposing to conditionally approve 

Section II, ‘‘Emission Limitations for 

PREPA San Juan and PREPA Palo 

Seco,’’ Subsection (A), Section III, 

‘‘Emission Limitations for PREPA 

Aguirre,’’ Subsection (A), Section V, 

‘‘Measurement methods and 

procedures,’’ Subsections (C), (D), and 

(F). 

The EPA is soliciting public 

comments on this proposed action. The 

EPA will accept comments from the 

public on this proposal for the next 60 

days and will consider these comments 

before taking final action. 

XI. Incorporation by Reference 

In this rule, the EPA is proposing to 

include in a final EPA rule, regulatory 

text that includes incorporation by 

reference. In accordance with 

requirements of 1 CFR 51.5, the EPA is 

proposing to incorporate by reference 

Puerto Rico’s RCAP, Rule 102, 

‘‘Definitions,’’ and Rule 210, ‘‘NonAttainment Provisions,’’ as well as 

portions of Rule 425, ‘‘Provisions for 

SO2 Non-Attainment Areas,’’ with a 

State/commonwealth effective date of 

November 21, 2022, and as described in 

Sections VI through VIII of this 

preamble. 

Specifically, the EPA is proposing to 

incorporate by reference the following 

sections of Rule 425: Section I, 

‘‘Applicability’’; Section II, ‘‘Emission 

Limitations for PREPA San Juan and 

PREPA Palo Seco,’’ Subsection (A); 

Section III, ‘‘Emission Limitations for 

PREPA Aguirre,’’ Subsection (A); 

Section IV, ‘‘Emission Limitations for 

San Juan and Guayama-Salinas NonAttainment Areas;’’ Section V, 

‘‘Measurement methods and 

procedures;’’ and Section VI, 

‘‘Contingency Measures.’’ These 

documents are available in the docket of 

this rulemaking through 

www.regulations.gov. 

XII. Statutory and Executive Order 

Reviews 

Additional information about these 

statutes and Executive Orders can be 

found at https://www.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Order 12866: Regulatory 

Planning and Review, and Executive 

Order 14094: Modernizing Regulatory 

Review 

This action is not a significant 

regulatory action as defined in 

Executive Order 12866, as amended by 

Executive Order 14094, and was 

therefore not submitted to the Office of 

Management and Budget (OMB) for 

review. 

B. Paperwork Reduction Act (PRA) 

This action does not impose an 

information collection burden under the 

PRA because this action does not 

impose additional requirements beyond 

those imposed by State law. 

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 will not 

impose any requirements on small 

entities beyond those imposed by State/ 

commonwealth law. 

D. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain any 

unfunded mandate as described in 

UMRA, 2 U.S.C.1531–1538, and does 

not significantly or uniquely affect small 

governments. This action does not 

impose additional requirements beyond 

those imposed by State/commonwealth 

law. Accordingly, no additional costs to 

State, local, or Tribal governments, or to 

the private sector, will result from this 

action. 

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 Sates, or on the 

distribution of power and 

responsibilities among the various 

levels of government. 

F. Executive Order 13175: Coordination 

With Indian Tribal Governments 

This action does not have Tribal 

implications, as specified in Executive 

Order 13175, because the SIP is not 

approved to apply on any Indian 

reservation land or in any other area 

where the EPA or an Indian Tribe has 

demonstrated that a Tribe has 

jurisdiction and will not impose 

substantial direct costs on Tribal 

governments or preempt Tribal law. 

Thus, Executive Order 13175 does not 

apply in 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 does not impose additional 

requirements beyond those imposed by 

State/commonwealth law. 

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 (NTTAA) 

Section 12(d) of the NTTAA directs 

the EPA to use voluntary consensus 

standards in its regulatory activities 


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79850 Federal Register / Vol. 89, No. 190 / Tuesday, October 1, 2024 / Proposed Rules 

unless to do so would be inconsistent 

with applicable law or otherwise 

impractical. The EPA believes that this 

action is not subject to the requirements 

of section 12(d) of the NTTAA because 

application of those requirements would 

be inconsistent with the CAA. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income 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. The EPA defines 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.’’ 

The PRDNER 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. Consistent with the EPA’s 

discretion under the CAA, the EPA 

evaluated the environmental justice 

considerations of this action, as is 

described above in the section titled, 

‘‘Environmental Justice 

Considerations.’’ The analysis was done 

for the purpose of providing additional 

context and information about this 

rulemaking to the public, and not as a 

basis of the 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. In addition, there is no information 

in the record inconsistent with the 

stated goal of E.O. 12898 of achieving 

environmental justice for communities 

with environmental justice concerns. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Sulfur dioxide, Reporting and 

recordkeeping requirements. 

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

Lisa Garcia, 

Regional Administrator, Region 2. 

[FR Doc. 2024–22466 Filed 9–30–24; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Parts 281 and 282 

[EPA–R04–UST–2024–0279; FRL–12181– 

01–R4] 

North Carolina: Final Approval of State 

Underground Storage Tank Program 

Revisions, Codification, and 

Incorporation by Reference 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The State of North Carolina 

(North Carolina) has applied to the 

Environmental Protection Agency (EPA) 

for final approval of revisions to its 

Underground Storage Tank Program 

(UST Program) under subtitle I of the 

Resource Conservation and Recovery 

Act (RCRA). Pursuant to RCRA, the EPA 

is proposing to approve revisions to 

North Carolina’s UST Program. This 

action is based on the EPA’s 

determination that the State’s revisions 

satisfy all requirements for UST 

program approval. This action also 

proposes to codify North Carolina’s 

revised UST Program and to incorporate 

by reference the State statutes and 

regulations that we have determined 

meet the requirements for approval. 

DATES: Comments on this proposed rule 

must be received on or before November 

1, 2024. 

ADDRESSES: You may send comments, 

identified by Docket ID No. EPA–R04– 

UST–2024–0279, by either of the 

following methods: 

• Federal eRulemaking Portal: 

https://www.regulations.gov (our 

preferred method). Follow the online 

instructions for submitting comments. 

• Email: giri.upendra@epa.gov. 

Include the Docket ID No. EPA–R04– 

UST–2024–0279 in the subject line of 

the message. 

Instructions: Submit your comments, 

identified by Docket ID No. EPA–R04– 

UST–2024–0279, via the Federal 

eRulemaking Portal at https://

www.regulations.gov. Follow the online 

instructions for submitting comments. 

Once submitted, comments cannot be 

edited or removed from https://

www.regulations.gov. The 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. The EPA will 

generally not consider comments or 

comment contents located outside of the 

primary submission (i.e., on the web, 

cloud, or other file sharing system). For 

additional submission methods, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit: 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

The EPA encourages electronic 

submittals and lists all publicly 

available docket materials electronically 

at https://www.regulations.gov. If you 

are unable to make electronic submittals 

or require alternative access to docket 

materials, please contact Upendra Giri, 

the contact listed in the FOR FURTHER

INFORMATION CONTACT provision below. 

The index of the docket and all publicly 

available docket materials for this action 

are available for review at https://

www.regulations.gov. 

Please also contact Upendra Giri if 

you need assistance in a language other 

than English or if you are a person with 

disabilities who needs a reasonable 

accommodation at no cost to you. For 

further information on EPA Docket 

Center services, please visit us online at 

https://www.epa.gov/dockets. 

FOR FURTHER INFORMATION CONTACT: 

Upendra Giri, RCRA Programs and 

Cleanup Branch, Land, Chemicals, and 

Redevelopment Division, U.S. 

Environmental Protection Agency, 

Region 4, Atlanta Federal Center, 61 

Forsyth Street SW, Atlanta, Georgia 

30303–8960; Phone number: (404) 562– 

8185, email address: giri.upendra@

epa.gov. Please contact Upendra Giri by 

phone or email for further information. 

SUPPLEMENTARY INFORMATION: For 

additional information, see the direct 

final rule published in the ‘‘Rules and 

Regulations’’ section of this Federal 

Register. 


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