Air Plan Approval; Mississippi; PSD and Air Quality Modeling Infrastructure Requirements for the 2015 8-Hour Ozone National Ambient Air Quality Standards

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R04-OAR-2024-0186; FRL-12250-02-R4]</DEPDOC> <SUBJECT>Air Plan Approval; Mississippi; PSD and Air Quality Modeling Infrastructure Requirements for the 2015 8-Hour Ozone National Ambient Air Quality Standards</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is approving a State Implementation Plan (SIP) submission provided by the State of Mississippi, through the Mississippi Department of Environmental Quality (MDEQ), via a letter dated February 28, 2024. Specifically, EPA is finalizing approval of updates to the incorporation by reference of Federal prevention of significant deterioration (PSD) rules in the Mississippi SIP. EPA is also converting the previous conditional approval of Mississippi's infrastructure SIP PSD and air quality modeling provisions for the 2015 Ozone National Ambient Air Quality Standards (NAAQS) to a full approval. EPA is also approving changes to public notice provisions for PSD permitting to provide for electronic notice (e-notice) and to remove the mandatory requirement to provide public notice in a newspaper, and other minor changes to the PSD rules. EPA is finalizing approval of these changes pursuant to the Clean Air Act (CAA or Act). </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This rule is effective December 2, 2024. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> EPA has established a docket for this action under Docket Identification No. EPA-R04-OAR-2024-0186. All documents in the docket are listed on the <E T="03">regulations.gov</E> website. Although listed in the index, some information may not be publicly available, <E T="03">i.e.,</E> Confidential Business Information 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 either electronically through <E T="03">www.regulations.gov</E> or in hard copy at the Air Regulatory Management 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. EPA requests that if at all possible, you contact the person listed in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section to schedule your inspection. The Regional Office's official hours of business are Monday through Friday 8:30 a.m. to 4:30 p.m., excluding Federal holidays. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Josue Ortiz Borrero, Air Regulatory Management 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) 562-8085. Mr. Ortiz Borrero can also be reached via electronic mail at <E T="03">ortizborrero.josue@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">I. Background</HD> EPA is approving changes to Mississippi's SIP submitted by the State on February 28, 2024. The changes include revising the State's new source review (NSR) permitting regulations at 11 Mississippi Administrative Code (MAC), Part 2, Chapter 2, <E T="03">Permit Regulations for the Construction and/or Operation of Air Emissions Equipment</E> (Chapter 2) and PSD permitting regulations at 11 MAC, Part 2, Chapter 5, <E T="03">Regulations for the Prevention of Significant Deterioration of Air Quality</E> (Chapter 5) to adopt relevant federal permitting regulations into the SIP. The PSD permitting changes at Chapter 5 amend MDEQ's incorporate by reference (IBR) date of the federal PSD regulations at 40 CFR 51.166(f) and 40 CFR 52.21 to December 27, 2023. EPA's approval of the December 27, 2023, IBR date at Chapter 5, Rule 5.2 adopts into the SIP changes to 40 CFR 52.21 that EPA promulgated in several rulemakings since Mississippi's last IBR update of February 17, 2016. These rulemakings include: “Source Determination for Certain Emission Units in the Oil and Natural Gas Sector” 81 FR 35622 (June 3, 2016); “Rescission of Preconstruction Permits Issued under the Clean Air Act” 81 FR 78043 (November 7, 2016); “Revisions to the Guideline on Air Quality Models: Enhancements to the AERMOD Dispersion Modeling System and Incorporation of Approaches to Address Ozone and Fine Particulate Matter” 82 FR 5182 (January 17, 2017)  <SU>1</SU> <FTREF/> at; “Prevention of Significant Deterioration (PSD) and Nonattainment New Source Review (NNSR): Project Emissions Accounting” 85 FR 74890 (November 24, 2020); and “New Source Review Errors Correction” 86 FR 37918 (July 19, 2021). The SIP revision also amends Mississippi's SIP-approved PSD rules to adopt public participation e-notice provisions consistent with EPA's October 5, 2016, rule “Revisions to Public Notice Provisions in Clean Air Act Permitting Programs”. <SU>2</SU> <FTREF/> The modeling updates at Chapter 2 and 5 respecting references to Appendix W in 40 CFR 52.21(l) support the state's request to convert EPA's March 1, 2023, conditional approval of the PSD requirements of elements 110(a)(2)(C), (D)(i)(II) (Prong 3), and (J), and the air quality modeling element under section 110(a)(2)(K), of Mississippi's 2015 8-hour ozone NAAQS infrastructure SIP (iSIP)  <SU>3</SU> <FTREF/> to a full approval. <SU>4</SU> <FTREF/> The SIP revision also includes minor changes to Mississippi's PSD regulations at Chapter 2  <SU>5</SU> and Chapter 5. The February 28, 2024, SIP submission provides additional changes to 11 MAC, Part 2, Chapter 2 to address NSR requirements, as well as minor grammatical errors which will be addressed in a separate rulemaking. <FTNT> <SU>1</SU>  The update to air quality modeling from the updated IBR date in 11 MAC, Part 2, Chapter 5, Rule 5.2, also updates modeling requirements at 11 MAC, Part 2, Chapter 2, Rule 2.5 because this Rule cross-references Rule 5.2 for purposes of air quality modeling. </FTNT> <FTNT> <SU>2</SU>   <E T="03">See</E> 81 FR 71613. </FTNT> <FTNT> <SU>3</SU>  On October 1, 2015, EPA promulgated a revised primary and secondary NAAQS for ozone, revising the 8-hour ozone standards from 0.075 parts per million (ppm) to a new more protective level of 0.070 ppm. <E T="03">See</E> 80 FR 65292 (October 26, 2015). Pursuant to section 110(a)(1) of the CAA, states are required to submit SIP revisions meeting the applicable requirements of section 110(a)(2) within three years after promulgation of a new or revised NAAQS or within such shorter period as EPA may prescribe. Section 110(a)(2) requires states to address basic SIP elements such as requirements for monitoring, basic program requirements, and legal authority that are designed to assure attainment and maintenance of the NAAQS. This particular type of SIP is commonly referred to as an “infrastructure SIP” or “iSIP.” States were required to submit such SIP revisions for the 2015 8-hour ozone NAAQS to EPA no later than October 1, 2018. </FTNT> <FTNT> <SU>4</SU>  Mississippi submitted two SIP submissions on September 6, 2019, and January 25, 2021, to address their 110(a)(1) and (2) infrastructure obligations for the 2015 ozone standard. Through previous rulemakings, EPA approved most of the iSIP elements for the 2015 ozone NAAQS. <E T="03">See</E> 87 FR 57832 (September 22, 2022), and 88 FR 9336 (February 13, 2023). On March 1, 2023, EPA finalized the conditional approval for the PSD infrastructure elements ( <E T="03">i.e.,</E> section 110(a)(2)(C), (D)(i)(II) (prong 3) and (J)), and the air quality modeling element of section 110(a)(2)(K), portion of the January 25, 2021, infrastructure SIP submission, as supplemented on November 18, 2022. The March 1, 2023, conditional approval of the PSD and air quality modeling iSIP provisions established a requirement for Mississippi to submit a final SIP submission that addresses the terms of the conditional approval commitment one year after EPA's conditional approval of these portions of Mississippi's ozone iSIP or March 1, 2024. Accordingly, on February 28, 2024, Mississippi submitted a final SIP revision in response to the conditional approval commitment to address the outdated references to the federal guideline on air quality modeling, by revising Chapter 2 and Chapter 5 to require the use of the current version of 40 CFR part 51, Appendix W (Guideline on Air Quality Models). </FTNT> Through a notice of proposed rulemaking (NPRM) published on September 16, 2024 (89 FR 75517), EPA proposed to approve the changes to 11 MAC Part 2, Chapter 2, Rules 2.5B(1) and B(2), <E T="03">Application Review;</E> 11 MAC, Part 2, Chapter 5, Rule 5.1, <E T="03">Purpose of this regulation;</E> Rule 5.2, <E T="03">Adoption of Federal Rules by Reference;</E> Rule 5.3, <E T="03">Definition of term “Administrator”;</E> Rule 5.4, <E T="03">Adoption of Federal Rules for Exclusions from Increment Consumption;</E> Rule 5.6 <E T="03">Applicability;</E> and Rule 5.7, <E T="03">Public Participation</E> into Mississippi's SIP and to convert the conditional approval of the portions of the 2015 8-hour ozone NAAQS iSIP that address the PSD related requirements of CAA sections 110(a)(2)(C), 110(a)(2)(D)(i)(II) (prong 3), and 110(a)(2)(J), and the modeling requirements of 110(a)(2)(K) to a full approval. <SU>6</SU> <FTREF/> The contents of Mississippi's submission, EPA's rationale for approving the changes, and EPA's rationale for converting the conditional approval action to full approval, are described in more detail in the September 16, 2024, NPRM. 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