2025-17048: Air Plan Approval; Kentucky; Emissions Inventory and Nonattainment New Source Review for the Henderson-Webster Sulfur Dioxide Nonattainment Area

Federal Register, Volume 90 Issue 170 (Friday, September 5, 2025) [Federal Register Volume 90, Number 170 (Friday, September 5, 2025)] [Proposed Rules] [Pages 42889-42895] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 2025-17048] ----------------------------------------------------------------------- ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 [EPA-R04-OAR-2025-0023; FRL-12899-01-R4] Air Plan Approval; Kentucky; Emissions Inventory and Nonattainment New Source Review for the Henderson-Webster Sulfur Dioxide Nonattainment Area

Agency

Environmental Protection Agency (EPA).

Action

Proposed rule. -----------------------------------------------------------------------

Summary

The Environmental Protection Agency (EPA) is proposing to approve two State Implementation Plan (SIP) revisions submitted by the Commonwealth of Kentucky, through the Energy and Environment Cabinet (Cabinet), Division of Air Quality (DAQ) on January 26, 2024, and February 15, 2024, to certify two requirements under the Clean Air Act (CAA or Act). These revisions establish that the Kentucky SIP satisfies the nonattainment new source review (NNSR) and base year emissions inventory requirements for the 2010 1-hour sulfur dioxide (SO2) national ambient air quality standard (NAAQS) for the Henderson-Webster SO2 nonattainment area (hereinafter ``Henderson-Webster SO2 Nonattainment Area'' or ``Area''). These actions are being proposed pursuant to the CAA.

Dates

Comments must be received on or before October 6, 2025.

Addresses

Submit your comments, identified by Docket ID No. EPA-R04- OAR-2025-0023 at regulations.gov. Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. EPA will generally not consider comments or comment contents located outside of the primary submission (i.e., on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

For Further Information Contact

Pearlene Williams-Miles, Multi-Air Pollutant Coordination Section, Air Planning and Implementation Branch, Air and Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 Forsyth Street SW, Atlanta, Georgia 30303-8960. The telephone number is (404) 562-9144. Ms. Williams-Miles can also be reached via electronic mail at [email protected].

Supplementary Information

I. Background

SO2 is a gas that is formed by the burning of fossil fuels from power plants and other industrial facilities, such as extracting metal from ore; natural sources, such as volcanoes; and locomotives, ships, and other vehicles and heavy equipment that burn fuel with a high sulfur content. SO2 is the component of greatest concern amongst sulfur oxides (SOx) and is used as the indicator for the larger group of gaseous SOx. Control measures that reduce SO2 [[Page 42890]] can generally be expected to reduce people's exposures to all gaseous SOx. On June 2, 2010, EPA revised the primary SO2 NAAQS. Specifically, EPA established a 1-hour SO2 standard at a level of 75 parts per billion (ppb), based on the 3-year average of the annual 99th percentile of 1-hour daily maximum concentrations.\1\ See 75 FR 35520 (June 22, 2010). The 1-hour 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, as determined in accordance with appendix T of 40 CFR part 50. See 75 FR 35520, codified at 40 CFR 50.17(a)-(b). --------------------------------------------------------------------------- \1\ This rule became effective on August 23, 2010, and revoked the 24-hour and annual primary SO2 standards. --------------------------------------------------------------------------- Upon promulgation of a new or revised SO2 NAAQS, section 107(d) of the CAA requires EPA to designate as nonattainment any area that is violating the NAAQS (or that contributes to ambient air quality in a nearby area that is violating the NAAQS). As part of the designation process for the 2010 1-hour SO2 NAAQS, the Henderson-Webster SO2 Nonattainment Area was designated as a nonattainment area in the fourth round of designations on December 21, 2020.2 3 These area designations became effective on April 30, 2021. See 86 FR 16055 (March 26, 2021). States with nonattainment areas for the SO2 NAAQS must provide nonattainment SIP revisions meeting the applicable requirements of CAA sections 110(a), 172, 191, and 192 \4\ for the SO2 NAAQS. EPA's regulations governing nonattainment SIPs are set forth at 40 CFR part 51, with specific procedural requirements and control strategy requirements residing at subparts F and G, respectively. --------------------------------------------------------------------------- \2\ See Round 4 SO2 Designations at https://www.epa.gov/sulfur-dioxide-designations/epa-completes-fourth-round-sulfur-dioxide-designations. \3\ The Henderson-Webster SO2 Nonattainment Area is comprised of a portion of Henderson County and a portion of Webster County. EPA designated the Henderson-Webster SO2 Nonattainment Area in 2020 based on a violating ambient air monitor--the Sebree data requirements rule (DRR) monitor (Air Quality System ID: 21-101-1011)--sited to characterize the maximum 1-hour SO2 concentrations in the area. (The DRR may be found at 40 CFR 51.1205). The extent of the partial county Henderson-Webster SO2 Nonattainment Area was defined based on air dispersion modeling during round 4 SO2 designations in 2020. See 40 CFR 81.318. \4\ Section 191(a) of the CAA directs states to submit SIPs for areas designated as nonattainment for the SO2 NAAQS to EPA within 18 months of the effective date of the designation. Under CAA section 192(a) these SIPs are required to demonstrate that their respective areas will attain the NAAQS as expeditiously as practicable, but no later than 5 years from the effective date of designation. In addition, sections 110(a) and 172(c), as well as EPA regulations at 40 CFR part 51, set forth substantive elements each SIP must contain to be approved by EPA. --------------------------------------------------------------------------- Section 172(c) directs states with nonattainment areas to submit a SIP that contains an attainment demonstration showing that the affected area will attain the relevant standard as expeditiously as practicable, but no later than the applicable statutory attainment date (April 30, 2026, for the Henderson-Webster SO2 Nonattainment Area).\5\ On April 23, 2014, EPA issued guidance for meeting the statutory requirements in SO2 SIPs under the 2010 revised NAAQS in a document entitled ``Guidance for 1-Hour SO2 Nonattainment Area SIP Submissions'' \6\ (hereinafter referred to as ``2014 SO2 Nonattainment Guidance'') which describes the statutory requirements for nonattainment at CAA section 172(c), including an accurate inventory of actual emissions from all sources in nonattainment areas; an attainment demonstration; a demonstration of reasonable further progress; implementation of Reasonably Available Control Measures (RACM) (including Reasonably Available Control Technologies (RACT)); NNSR; enforceable emissions limitations and control measures; and adequate contingency measures for the affected area. For EPA to fully approve a SIP revision as meeting the requirements of CAA sections 110, 172, and 191-192 and EPA's regulations at 40 CFR part 51, the SIP for the affected area must demonstrate to EPA's satisfaction that each of the requirements have been met. State air agencies with nonattainment areas for the 2010 1- hour primary SO2 NAAQS are required to submit a SIP revision that addresses these requirements within 18 months after an area is designated nonattainment (no later than October 30, 2022, for the Henderson-Webster SO2 Nonattainment Area).\7\ Kentucky's January 26, 2024, and February 15, 2024, SIP revisions address the air agency's NNSR permitting and emissions inventory obligations pursuant to section 172(c)(5) and 172(c)(3) of the Act, respectively. --------------------------------------------------------------------------- \5\ Soon after the 1990 amendments to the CAA were enacted by Congress, EPA issued comprehensive guidance on SIPs in a document entitled the ``General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990,'' published in the Federal Register at 57 FR 13498 (April 16, 1992) (General Preamble). Among other things, the General Preamble addressed SO2 SIPs and fundamental principles for SIP control strategies. Id. at 13545-49, 13567-68. \6\ See https://www.epa.gov/sites/production/files/2016-06/documents/20140423guidance_nonattainment_sip.pdf. \7\ See CAA section 191(a). ---------------------------------------------------------------------------

III. Proposed Actions

For the reasons discussed above, EPA is proposing to approve Kentucky's January 26, 2024, and February 15, 2024, SIP revisions containing a certification that its existing SIP-approved NNSR program meets the NNSR requirements for the 2010 SO2 NAAQS and an emissions inventory, respectively, for the Henderson-Webster SO2 Nonattainment Area.

IV. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. See 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, these proposed actions merely propose to approve state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, these proposed actions: Are not significant regulatory actions subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993); Are not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866; Do not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.); Are 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.); Do 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); Do not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999); Are not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because they approve a state program; Are not significant regulatory actions subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and Are not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA. In addition, the SIP is not approved to apply on any Indian reservation land or in any other area where 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). List of Subjects in 40 CFR Part 52 Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Sulfur oxides. Authority: 42 U.S.C. 7401 et seq. [[Page 42895]] Dated: August 27, 2025. Kevin McOmber, Regional Administrator, Region 4. [FR Doc. 2025-17048 Filed 9-4-25; 8:45 am] BILLING CODE 6560-50-P