90 FR 134 pgs. 31877-31881 - Air Plan Approval; Guam; Base Year Emissions Inventory for the 2010 1-Hour Sulfur Dioxide National Ambient Air Quality Standard for the Piti-Cabras Nonattainment Area
Type: RULEVolume: 90Number: 134Pages: 31877 - 31881
Pages: 31877, 31878, 31879, 31880, 31881Docket number: [EPA-R09-OAR-2025-0268; FRL-12868-02-R9]
FR document: [FR Doc. 2025-13328 Filed 7-15-25; 8:45 am]
Agency: Environmental Protection Agency
Official PDF Version: PDF Version
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2025-0268; FRL-12868-02-R9]
Air Plan Approval; Guam; Base Year Emissions Inventory for the 2010 1-Hour Sulfur Dioxide National Ambient Air Quality Standard for the Piti-Cabras Nonattainment Area
AGENCY:
Environmental Protection Agency (EPA).
ACTION:
Direct final rule.
SUMMARY:
The Environmental Protection Agency (EPA) is taking direct final action to approve a revision to Guam's State Implementation Plan (SIP) under section 110(k)(3) of the Clean Air Act (CAA or "the Act"). This revision concerns the base year emissions inventory for the Piti-Cabras, Guam sulfur dioxide (SO 2 ) nonattainment area ("Piti-Cabras area" or NAA) for the 2010 1-hour SO 2 National Ambient Air Quality Standard (NAAQS, "standard," or "2010 SO 2 NAAQS").
DATES:
This rule is effective October 14, 2025 without further notice, unless the EPA receives adverse comments by August 15, 2025. If we receive such comments, we will publish a timely withdrawal in the Federal Register to notify the public that this direct final rule will not take effect.
ADDRESSES:
Submit your comments, identified by Docket ID No. EPA-R09-OAR-2025-0268 at https://www.regulations.gov. For comments submitted at Regulations.gov, follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. 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, please contact the person identified in the FOR FURTHER INFORMATION CONTACT section. For the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a language other than English or if you are a person with a disability who needs a reasonable accommodation at no cost to you, please contact the person identified in the FOR FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT:
Khoi Nguyen, Geographic Strategies and Modeling Section, Planning & Analysis Branch, Air & Radiation Division, EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105; telephone number: 415-947-4120; email address: Nguyen.Khoi@epa.gov.
SUPPLEMENTARY INFORMATION:
Throughout this document, "we," "us," and "our" refer to the EPA.
Table of Contents
I. Background
II. Guam EPA's Base Year Emissions Inventory for the Piti-Cabras Nonattainment Area
III. The EPA's Evaluation
IV. Public Comment and Final Action
V. Statutory and Executive Order Reviews
I. Background
On June 22, 2010, the EPA published in the Federal Register a strengthened, primary 1-hour SO 2 NAAQS, establishing a new standard at a level of 75 parts per billion (ppb), based on the 3-year average of the annual 99th percentile of daily maximum 1-hour average concentrations of SO 2 . 1 Following promulgation of a new or revised NAAQS, the EPA is required to designate all areas of the country as either "attainment," "nonattainment," or "unclassifiable."? 2 On December 21, 2017, the EPA signed a notice designating six areas in three States and two territories as nonattainment in the third round of SO 2 designations, effective April 9, 2018. 3 With that action, the EPA designated as nonattainment the portion of Guam within a 6.074-km radius centered on UTM Easting 249,601.60 m, and UTM Northing 1,489,602.00 m (UTM Zone 55N). 4
Footnotes:
1 ?On June 2, 2010, the EPA signed the final rule titled, "Primary National Ambient Air Quality Standard for Sulfur Dioxide," 75 FR 35520 (June 22, 2010), codified at 40 CFR part 50.
2 ?CAA section 107(d)(1).
3 ?83 FR 1098 (January 9, 2018).
4 ?For designations technical discussions, see the Technical Support Document, Chapter 11: Intended Round 3 Area Designations for the 2010 1-Hour SO 2 Primary National Ambient Air Quality Standard for Guam. EPA Office of Air and Radiation, December 2017, Section 3, 6-26, available in the docket for this action.
[top] The Piti-Cabras area is located on the western side of the island of Guam, centered on the Piti and Cabras power plants, which are both owned by Guam Power Authority (GPA). The Piti facility (also referred to as Marianas Energy Company (MEC) by Guam) consists of two baseload electric generating units (8 and 9). Piti 8 and 9 are two 45.2 megawatt (MW) diesel engines. The Cabras facility consists of two baseload electric generating units (1 and 2) that
Footnotes:
5 ?Piti/TEMES 7 is a 40 MW combustion turbine and is also owned by GPA.
6 ?"Technical Support Document (TSD) for the Piti-Cabras, Guam 2010 1-Hour SO 2 Nonattainment Area Clean Data Determination Modeling Analysis," EPA Region 9, June 2025.
Section 191 of the CAA directs states containing an area designated nonattainment for the 2010 SO 2 NAAQS to develop and submit a nonattainment area SIP to the EPA within 18 months of the effective date of an area's designation as nonattainment. The nonattainment area SIP revision (also referred to as an attainment plan) must meet the requirements of subparts l and 5 of part D, of Title 1 of the CAA, 42 U.S.C. 7401 et seq., and provide for attainment of the NAAQS by the applicable statutory attainment date. 7 To be approved by the EPA, under section 192(a), these nonattainment area SIPs must provide for attainment of the NAAQS as expeditiously as practicable, but no later than five years from the effective date of designation.
Footnotes:
7 ?See sections 172 and 191-192 of the CAA.
The Guam Environmental Protection Agency (Guam EPA) was required to prepare and submit to the EPA a nonattainment area SIP by October 9, 2019, to bring the area into attainment by the attainment date of April 9, 2023. However, Guam EPA failed to submit a complete attainment plan for the area by the October 9, 2019 deadline. On November 3, 2020, the EPA issued a finding that Guam EPA failed to submit the required attainment plan for the Piti-Cabras area. 8 Pursuant to section 179 of the CAA and 40 CFR 52.31, the November 3, 2020 finding triggered sanctions clocks. More specifically, under 40 CFR 52.31, the offset sanction in CAA section 179(b)(2) would be imposed 18 months after December 3, 2020 effective date of the finding, and the highway funding sanction in CAA section 179(b)(1) would be imposed six months after the offset sanction was imposed, unless the EPA determined that a subsequent SIP submission corrected the identified deficiencies before the applicable deadlines. 9
Footnotes:
8 ?85 FR 69504 (November 3, 2020).
9 ?See 40 CFR 52.31(d)(5).
The finding also started a two-year clock by which the EPA is required under CAA section 110(c) to promulgate a Federal Implementation Plan (FIP) for the area, unless Guam EPA submits, and the EPA approves, a SIP for the area before December 3, 2022.
On December 19, 2024, the EPA issued a finding that the Piti-Cabras nonattainment area failed to attain the 2010 SO 2 NAAQS by the statutory attainment date of April 9, 2023. 10 This finding triggered a requirement for Guam EPA to submit a plan demonstrating attainment of the 2010 SO 2 NAAQS as expeditiously as practicable, but no later than December 19, 2029. 11 In that action, the EPA noted that the Guam's submission of a complete SO 2 attainment plan for the new attainment date in response to this finding of failure to attain would also address the Territory's existing obligations to submit an attainment plan for the 2010 SO 2 NAAQS.
Footnotes:
10 ?89 FR 103819.
11 ?Id. at 103822.
On June 20, 2025, the EPA proposed to determine that the Piti-Cabras area is attaining the 2010 SO 2 NAAQS and qualifies for a Clean Data Determination (CDD) under the EPA's Clean Data Policy. 12 If the EPA finalizes the CDD, it would suspend the requirements for the Piti-Cabras area to submit an attainment demonstration and certain other associated nonattainment planning requirements for so long as the Piti-Cabras area continues to attain the 2010 SO 2 NAAQS. A final CDD would also suspend the EPA's obligation to promulgate a FIP and the sanctions clocks associated with the finding of failure to submit issued on November 3, 2020, 13 with regard to the attainment demonstration, demonstrations for reasonably available control measures and reasonably available control technology (RACM/RACT), reasonable further progress (RFP), emissions limitations and control measures as necessary to provide for attainment, and contingency measures. Guam EPA would still be required to submit an emissions inventory required by CAA section 172(c)(3) and a nonattainment new source review (NNSR) program required by CAA section 172(c)(5). 14
Footnotes:
12 ?90 FR 26235 (June 20, 2025).
13 ?85 FR 69504.
14 ?Guam EPA submitted a SIP revision addressing NNSR on March 13, 2025. The EPA found this submittal complete and proposed to approve it into the SIP on June 18, 2025, 90 FR 25984.
II. Guam EPA's Base Year Emissions Inventory for the Piti-Cabras Nonattainment Area
Guam EPA submitted the emissions inventory element to the EPA on June 6, 2025. 15 The submittal is titled "Guam Environmental Protection Agency Piti-Cabras SO 2 State Implementation Plan Emission Inventory Technical Support Document" ("EI submittal"). In the EI submittal, Guam EPA reviewed and compiled actual emissions from sources of SO 2 in the Piti-Cabras area for the base year emissions inventory requirement. Guam's 2020 base year SO 2 emissions inventory for the Piti-Cabras area, by emission source category, is contained in Table 1 in this document.
Footnotes:
15 ?Letter dated June 6, 2025, from Michelle C. R. Lastimoza, Administrator, Guam EPA, to Josh F. W. Cook, Regional Administrator, U.S. Environmental Protection Agency Region 9 (submitted electronically June 6, 2025).
[top] Guam EPA estimated SO 2 emissions for point and non-point sources. The point source category was the largest SO 2 emissions source category. In 2020, GPA operated six energy generation units (EGUs) in the NAA, which contributed the majority of point source emissions. Additional point sources consisted of generators and boilers operated by the Department of Defense (DoD)/United States Navy (US Navy). SO 2 emissions from back-up generators operated by other commercial entities were assumed to be negligible due to their likely limited run hours and because, since 2011, Guam territorial law has required all diesel imported for distribution and sale to be ultra low sulfur diesel. 16 In the non-point source categories, port emissions were a significant contributor. The port of Guam receives vessel calls from both commercial and US Navy ships. Accordingly, Guam EPA estimated marine SO 2 emissions from commercial and U.S. Navy ships hoteling in the port. Guam EPA was unable to estimate emissions from other activities at the port, other non-point sources, and on-road and non-road mobile sources due to lack of data. However, we find that the emissions from these sources would have a negligible impact on the total SO 2 emissions in the NAA because of the ultra low sulfur diesel requirement. While exceptions were provided for certain EGUs and U.S. Navy sources, these sources are already reflected in the emissions inventory. In particular, the GPA EGUs are the largest emissions
Footnotes:
16 ?10 GCA section 49119.
| Source category | Source description | Estimated SO 2 emissions 2020 (tons/year) |
|---|---|---|
| Point Sources | GPA EGUs | 12,274.54 |
| DoD EGUs | 0.0264 | |
| DoD Boilers | 9.04 | |
| Non-point Sources | Marine Sources | 234.31 |
| Total | 12,517.92 | |
| Source: EI submittal, Table 8. | ||
All point source emissions were calculated using the EPA's AP-42 emissions factors? 17 together with the sulfur content of the fuel, as determined by shipment records, and 2020 annual fuel consumption records (Table 2). For non-point sources, marine emissions from hoteling vessels were estimated using port of Guam annual vessel call reports and EPA emissions factors. 18
Footnotes:
17 ?AP-42 is the primary compilation of the EPA's emissions factor information. See https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors-stationary-sources.
18 ?Ports Emissions Inventory Guidance: Methodologies for Estimating Port-Related and Goods Movement Mobile Source Emissions. Office of Transportation and Air Quality, US EPA (April 2022).
| Guam power authority plant | Nominal power (megawatts) | Fuel sulfur content (% weight/weight ) | SO 2 emissions 2020 (tons/year) |
|---|---|---|---|
| Piti 8 | 44.2 | 1.74 or 0.99 | 2791.74 |
| Piti 9 | 44.2 | 1.74 or 0.99 | 2666.84 |
| Cabras 1 | 66 | 1.74 or 0.99 | 3389.2 |
| Cabras 2 | 66 | 1.74 or 0.99 | 3426.55 |
| (TEMES) Piti 7 | 40 | 0.001 | 0.11 |
| Tenjo Vista | 26.4 | 0.001 | 0.1036 |
| Total | 286.80 | 12,274.54 | |
| Source: EI submittal, Table 1. | |||
III. The EPA's Evaluation
We have reviewed Guam EPA's public notice and comment procedures in the EI submittal and find that Guam EPA's EI submittal meets the completeness criteria in 40 CFR part 51 Appendix V, which must be met before formal EPA review.
The EPA's 2014 SO 2 Nonattainment Guidance further describes the statutory elements comprising an SO 2 attainment plan. These requirements include submission of a comprehensive, accurate and current base year emissions inventory of all sources of SO 2 within the nonattainment area, per CAA section 172(c)(3). 19
Footnotes:
19 ?See "Guidance for 1-Hour SO 2 Nonattainment Area SIP Submissions" (April 23, 2014).
Guam EPA selected 2020 for the base year emissions inventory for the Piti-Cabras area, which is appropriate because it is a recent year that is representative of conditions leading to nonattainment. In particular, it is part of the three-year design value period for which the EPA determined that the Piti-Cabras area failed to attain the 2010 SO 2 NAAQS by its original attainment date. 20
Footnotes:
20 ?89 FR 103819, 103821-89 FR 103822 (December 19, 2024) ("the relevant three-year DV period for the April 9, 2023 attainment date was from 2020-2022").
We find the emissions estimation methodologies employed in the EI submittal appropriate as they relied on the EPA's AP-42 and other recommended emissions factors and EPA emissions estimation guidance. All emission calculations, source data, and supporting documentations were included in the EI submittal.
In conclusion, the EPA has evaluated Guam EPA's EI submittal for the Piti-Cabras area and has determined that it was developed in a manner consistent with CAA section 172(c)(3) and with applicable EPA guidance.
IV. Public Comment and Final Action
As authorized in section 110(k)(3) of the Act, the EPA is fully approving the submitted base year emissions inventory based on our determination that it fulfills all relevant requirements. The EPA is approving Guam EPA's EI submittal as meeting the requirements of CAA section 172(c)(3). Specifically, we are finding that the submittal satisfies the base year emissions inventory requirement triggered by the December 19, 2024 finding of failure to attain, as well as the Territory's obligation to submit a base year inventory for the 2010 SO 2 NAAQS stemming from the EPA's designation of the area as nonattainment in 2017. With this final action, the emissions inventory element of the EPA's obligation as to this nonattainment area under the consent decree in Center for Biological Diversity et al. v. Regan, No. 4:24-cv-01900 (N.D. Cal.), doc. 28, paragraphs 1.c-d, 2, will also be met.
[top] We do not anticipate that anyone will object to this approval, therefore, we are finalizing approval without first
Please note that if the EPA receives adverse comment on an amendment, paragraph, or section of this rule and if that provision may be severed from the remainder of the rule, the EPA may adopt as final those provisions of the rule that are not the subject of an adverse comment.
V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this proposed action merely proposes to approve state law as meeting federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action:
• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq. );
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq. );
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it proposes to approve a state program;
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
• Is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the Clean Air Act.
In addition, 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. In those areas of Indian country, the rule does not have Tribal implications and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).
This action is subject to the Congressional Review Act, and the EPA will submit a rule report to each House of the Congress and to the Comptroller General of the United States. This action is not a "major rule" as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by September 15, 2025. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this action for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements. (See section 307(b)(2).)
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Sulfur oxides.
Dated: July 7, 2025.
Joshua F.W. Cook,
Regional Administrator, Region IX.
Part 52, chapter I, title 40 of the Code of Federal Regulations is amended as follows:
PART 52-APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
1. The authority citation for Part 52 continues to read as follows:
Authority:
42 U.S.C. 7401 et seq.
Subpart AAA-Guam
2. Section 52.2670 is amended by adding in paragraph (e), under the table heading "EPA Approved Guam Nonregulatory Provisions and Quasi-Regulatory Measures" an entry for "Guam Environmental Protection Agency Piti-Cabras SO 2 State Implementation Plan Emission Inventory Technical Support Document" after the entry for "Appendix K: Inventory data for 1973."
§?52.2670 Identification of plan.
(e) * * *
| Name of SIP provision | Applicable geographic or nonattainment area | State submittal date | EPA approval date | Explanation |
|---|---|---|---|---|
| Implementation Plan for Compliance With the Ambient Air Quality Standards For Territory of Guam | ||||
| * * * * * * * | ||||
| Guam Environmental Protection Agency Piti-Cabras SO 2 State Implementation Plan Emission Inventory Technical Support Document | Piti-Cabras Nonattainment Area | June 6, 2025 | 7/16/2025, 90 FR [Insert Federal Register page where the document begins] | Submitted on June 6, 2025 as an attachment to a letter dated June 6, 2025. |
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[FR Doc. 2025-13328 Filed 7-15-25; 8:45 am]
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