Air Plan Approval; Ohio; Muskingum River 2010 Sulfur Dioxide Redesignation and Maintenance Plan

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Parts 52 and 81</CFR> <DEPDOC>[EPA-R05-OAR-2025-0165; FRL-12974-01-R5]</DEPDOC> <SUBJECT>Air Plan Approval; Ohio; Muskingum River 2010 Sulfur Dioxide Redesignation and Maintenance Plan</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is proposing to redesignate the Muskingum River sulfur dioxide (SO <E T="52">2</E> ) nonattainment area, located in Center Township in Morgan County and Waterford Township in Washington County, Ohio, to attainment for the 2010 SO <E T="52">2</E> National Ambient Air Quality Standard (NAAQS). EPA is also proposing to approve Ohio's maintenance plan for the area and Ohio's Director's Final Findings and Orders (DFFOs), issued March 26, 2025. Ohio submitted the request for approval on March 31, 2025. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before November 3, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R05-OAR-2025-0165 at <E T="03">https://www.regulations.gov,</E> or via email to <E T="03">arra.sarah@epa.gov.</E> For comments submitted at <E T="03">Regulations.gov</E> , follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from the docket. EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI), Proprietary Business Information (PBI), 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 ( <E T="03">i.e.,</E> on the web, cloud, or other file sharing system). For additional submission methods, please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section. For the full EPA public comment policy, information about CBI, PBI, or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets.</E> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Gina Harrison, Air and Radiation Division (AR18J), Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604, (312) 353-6956, <E T="03">harrison.gina@epa.gov.</E> The EPA Region 5 office is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding Federal holidays and facility closures. </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">I. What is EPA proposing?</HD> EPA is proposing to determine that the Muskingum River SO <E T="52">2</E> nonattainment area, located in Center Township in Morgan County and Waterford Township in Washington County, Ohio, is attaining the 2010 SO <E T="52">2</E> NAAQS, based on quality-assured and certified monitoring data for the period 2015-2024, in accordance with Ohio's March 31, 2025, request. EPA has determined that the area is attaining the 2010 SO <E T="52">2</E> NAAQS and that the improvement in air quality is due to permanent and enforceable SO <E T="52">2</E> emission reductions in the area. Therefore, EPA is proposing to change the legal designation of the Muskingum River SO <E T="52">2</E> nonattainment area to attainment for the 2010 SO <E T="52">2</E> NAAQS. EPA is also proposing to approve Ohio's maintenance plan into the Ohio State Implementation Plan (SIP), which is designed to ensure that the area will continue to meet the SO <E T="52">2</E> NAAQS. Finally, EPA is proposing to approve the site-specific DFFOs which were issued on March 26, 2025, into the SIP. Ohio's submittal, which includes the maintenance plan and DFFOs, will be available for public review as part of the rulemaking docket for this action. <HD SOURCE="HD1">II. What is the background for these actions?</HD> On June 22, 2010 (75 FR 35520), EPA revised the primary SO <E T="52">2</E> NAAQS, establishing a new 1-hour standard of 75 parts per billion (ppb), which is met at an ambient air quality monitoring site when the 3-year average of the annual 99th percentile of daily maximum 1-hour average concentrations is less than or equal to 75 ppb, as determined in accordance with appendix T of 40 CFR part 50. 40 CFR 50.17(a)-(b). EPA promulgated designations for this standard in four rounds. On June 3, 2011, Ohio submitted its recommendations to EPA to designate certain areas of the State as attaining, not attaining, or unclassifiable for attaining the SO <E T="52">2</E> NAAQS. Ohio recommended that the area located in southeastern Ohio that includes Center Township in Morgan County and Waterford Township in Washington County be designated as nonattainment for the 2010 SO <E T="52">2</E> NAAQS. EPA concurred with Ohio's analysis and, on August 15, 2013, published a final action designating the area as nonattainment of the 2010 SO <E T="52">2</E> NAAQS, effective October 4, 2013 (78 FR 47191). Under section 192(a) of the Clean Air Act (CAA), States are also required to submit attainment plans to demonstrate that the respective areas will attain the NAAQS as expeditiously as practicable, but no later than five years from the effective date of designation. Ohio submitted statewide nonattainment area SIPs to EPA on April 3, 2015, and October 13, 2015, and submitted supplemental attainment plans for the Muskingum River SO <E T="52">2</E> nonattainment area on June 24, 2020, July 28, 2022, and May 23, 2023. Ohio's fully approved attainment plan included modeling for the Globe Metallurgical, Inc., facility (Globe) and the State's DFFOs, which set forth emission limits at Globe and monitoring and testing requirements to confirm the source modeling characterization (September 8, 2023, 88 FR 61969). Ohio's modeled emissions for this area showed the DFFO-required emission limits for Globe, in conjunction with the SO <E T="52">2</E> reductions from the permanent retirement of the Muskingum River Power Plant in 2015, provide for attainment of the SO <E T="52">2</E> standard throughout the area. In addition, the DFFOs required the installation and operation of an ambient air monitor downwind of Globe for a period of three years. On March 31, 2025, Ohio submitted a redesignation request and maintenance plan to EPA for the Muskingum River SO <E T="52">2</E> nonattainment area for the 2010 SO <E T="52">2</E> NAAQS. The submitted redesignation request and maintenance plan include complete quality-assured ambient air quality monitoring data meeting the 2010 SO <E T="52">2</E> standard from 2015 to 2024. These NAAQS attainment monitoring demonstrations, in addition to decreases in emission levels attributable to the shutdown of the Muskingum River Power Plant and the promulgation of emission limits and other measures set forth in Ohio's DFFOs to Globe, provide the framework for Ohio's request for redesignation to attainment for the Muskingum River SO <E T="52">2</E> nonattainment area. In addition, Ohio is requesting that EPA approve the March 26, 2025, revised DFFOs that replace emission limits established in the 2020 DFFOs for Globe to provide for maintenance in the area. The 2020 DFFOs contain emission limits that are currently in Ohio's approved SIP. Ohio is also requesting that EPA approve the new emission limits from the March 26, 2025, revised DFFOs into the SIP. Under section 107(d)(3)(E) of the CAA, EPA may not promulgate a redesignation of a nonattainment area (or portion thereof) unless: 1. EPA has determined that the area has attained the NAAQS; 2. EPA has fully approved the applicable implementation plan for the area under section 110(k) of the CAA; 3. EPA has determined that improvement in air quality is due to permanent and enforceable reductions in emissions resulting from implementation of the applicable implementation plan and applicable Federal air pollution control regulations and other permanent and enforceable reductions; 4. EPA has fully approved a maintenance plan for the area under section 175A of the CAA; and 5. The State containing such area has met all requirements applicable to the area under section 110 of the CAA and part D. On April 16, 1992 (57 FR 13498), EPA provided guidance on redesignations in the “General Preamble for the Implementation of Title I of the CAA Amendments of 1990” and supplemented this guidance on April 28, 1992 (57 FR 18070). EPA has provided further guidance on processing redesignation requests in policy memoranda. <HD SOURCE="HD1">III. What is EPA's analysis of Ohio's redesignation request and maintenance plan?</HD> On October 2, 2023, Ohio submitted a request that EPA redesignate the Muskingum River SO <E T="52">2</E> nonattainment area to attainment and a SIP revision containing a maintenance plan for the area. EPA's evaluation of Ohio's redesignation request and maintenance plan was based on consideration of the five redesignation criteria provided under CAA section 107(d)(3)(E). <E T="03">Criterion (1)—The Muskingum River SO</E> <E T="52">2</E> <E T="03">Nonattainment Area has Attained the 2010 SO</E> <E T="52">2</E> <E T="03">NAAQS.</E> In accordance with CAA section 107(d)(3)(E)(i), for redesignation of a nonattainment area to attainment, the CAA requires EPA to determine that the area has attained the applicable NAAQS. In accordance with 40 CFR 50.17 and appendix T of part 50, an area is attaining the 1-hour primary SO <E T="52">2</E> standard at ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 50k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━