Finding of Failure To Attain; Air Plan Approval; Indiana; Huntington County Sulfur Dioxide Attainment Plan

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R05-OAR-2023-0564; FRL-12835-01-R5]</DEPDOC> <SUBJECT>Finding of Failure To Attain; Air Plan Approval; Indiana; Huntington County Sulfur Dioxide Attainment 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 find that the Huntington County, Indiana nonattainment area failed to attain the 2010 Sulfur Dioxide (SO <E T="52">2</E> ) National Ambient Air Quality Standard (NAAQS) by the applicable attainment date of April 9, 2023. EPA is also proposing to approve revisions into the Indiana State Implementation Plan (SIP) intended to provide for attainment of the 2010 SO <E T="52">2</E> NAAQS for the Huntington County nonattainment area. These SIP submissions include Indiana's attainment demonstration and other planning elements required under the Clean Air Act (CAA), and a Commissioner's Order containing enforceable emission limits. Further, EPA is proposing to find that the provisions of Indiana's SIP submittal adequately provide for attainment of the NAAQS and that the plan meets all other applicable CAA requirements. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before July 18, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R05-OAR-2023-0564 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 to EPA's docket at <E T="03">https://www.regulations.gov</E> 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> Liz Selbst, Air and Radiation Division (AR-18J), Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604, (312) 886-4746, <E T="03">selbst.elizabeth@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. </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document whenever “we,” “us,” or “our” is used, we mean EPA. <HD SOURCE="HD1">I. Background</HD> On June 22, 2010 (75 FR 35520), EPA published a revised primary SO <E T="52">2</E> NAAQS, establishing a new one-hour standard of 75 parts per billion (ppb). On August 21, 2015 (80 FR 51052), EPA issued the Data Requirements Rule (DRR), which required State air agencies to characterize air quality around sources that emitted 2,000 tons per year (tpy) or more of SO <E T="52">2</E> . EPA has identified the U.S. Mineral Wool facility, also known as “Isolatek,” as an emissions source that may have been contributing to violations of the 2010 SO <E T="52">2</E> NAAQS based on air quality modeling conducted by EPA and used in support of the DRR. Isolatek is located in the Huntington County, Indiana nonattainment area for the 2010 SO <E T="52">2</E> NAAQS. EPA's air quality modeling, conducted in 2015 using estimated actual emissions from the Isolatek facility, found that the 3-year average of the annual 99th percentile of daily maximum one-hour average SO <E T="52">2</E> concentrations exceeded the 75 ppb level of the NAAQS. EPA's March 15, 2016, response to the initial submittal of DRR sources from the Indiana Department of Environmental Management (IDEM) is included in the docket for this rulemaking. Evidence of IDEM's selection of the modeling pathway to characterize air quality in the area surrounding the Isolatek facility on June 30, 2016, is also included in the docket for this rulemaking. The Isolatek facility is the only listed DRR source in the Huntington area and there is no approved SO <E T="52">2</E> monitoring network to characterize air quality in its vicinity. IDEM did not include updated air quality information for the Huntington area in its letter of designations recommendations for the 2010 SO <E T="52">2</E> NAAQS. Therefore, during the initial area designations process, EPA relied on the prior EPA air quality modeling, which indicated that the Huntington area may have been violating the 2010 SO <E T="52">2</E> NAAQS, and which led EPA to include Isolatek on the list of sources subject to DRR requirements. On August 22, 2017, EPA notified IDEM that we intended to designate the Huntington area as nonattainment, based on the best information available to EPA at the time of designation, which was EPA's air quality modeling indicating that the area may have been violating the 2010 SO <E T="52">2</E> NAAQS. On January 9, 2018, EPA finalized the third round of initial area designations for the 2010 SO <E T="52">2</E> NAAQS. Based on prior air quality modeling information, EPA designated Huntington Township, a partial area of Huntington County, Indiana, which includes the Isolatek facility, as nonattainment for the 2010 SO <E T="52">2</E> NAAQS with an effective date of April 9, 2018 (83 FR 1098). Pursuant to CAA section 192(a), 42 U.S.C. 7514a(a), EPA established an attainment date of no later than five years after the effective date of the nonattainment area designation, which was April 9, 2023. <HD SOURCE="HD1"> II. Proposed Finding of Failure To Attain the 2010 One-Hour SO <E T="0132">2</E> NAAQS </HD> CAA section 179(c)(1) requires EPA to determine whether a nonattainment area attained an ambient air quality standard by the applicable attainment date based on the area's air quality as of the attainment date. As stated in EPA's April 23, 2014, “Guidance for 1-Hour SO <E T="52">2</E> Nonattainment Area SIP Submissions” (“April 2014 SO <E T="52">2</E> guidance”), 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 when determining the attainment status of SO <E T="52">2</E> nonattainment areas. Under EPA regulations in 40 CFR 50.17, the 2010 SO <E T="52">2</E> standard is met at a monitoring site (or in the case of dispersion modeling, at an ambient air quality receptor location) when the three-year average of the annual 99th percentile of daily maximum one-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)). Design values are calculated by computing the three-year average of the annual 99th percentile daily maximum one-hour average concentrations. When calculating one-hour primary standard design values based on modeling, the modeled concentration is compared to the one-hour SO <E T="52">2</E> NAAQS of 196.4 micrograms per cubic meter. An SO <E T="52">2</E> one-hour primary standard design value is valid if it encompasses three consecutive calendar years of complete monitoring data or modeling data. See appendix T of 40 CFR part 50. As of this action, and as of the statutory attainment date of April 9, 2023, there is no approved SO <E T="52">2</E> monitoring network in the Huntington area. The best air quality information available to EPA to characterize air quality in the area on the attainment date was the air quality modeling that was used to support the DRR. As part of the State's SO <E T="52">2</E> attainment plan for this area, IDEM submitted control measures on November 6, 2023, that included enforceable allowable emissions limits for the Isolatek facility (see Section III, “Proposed Approval of Indiana's SIP Submittal,” of this preamble for discussion of the control strategy). On February 12, 2024, IDEM supplemented the November 6, 2023, SIP submittal with Commissioner's Order 2023-Air-02, which revised Commissioner's Order 2023-Air-01, which had been included in the November 6, 2023, submittal. In this notice of proposed rulemaking, we are referring to the updated Order 2023-Air-02 as the “Commissioner's Order,” which established compliance requirements for the one-hour SO <E T="52">2</E> emissions limits, which were effective on March 1, 2024. In other words, the control measures that EPA is proposing to approve in the following section of this action were not in place as of the statutory attainment date of April 9, 2023. Therefore, based on EPA's air quality modeling used to support the DRR, EPA has determined that the area may have been violating the 2010 SO <E T="52">2</E> NAAQS prior to full implementation of the control strategy. EPA is proposing to find that, as of the applicable attainment date of April 9, 2023, the Huntington area failed to attain the 2010 SO <E T="52">2</E> NAAQS by the attainment date. The consequences for an SO <E T="52">2</E> nonattainment area that fails to attain a NAAQS by the ap ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 49k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━