Air Plan Approval; South Carolina; Charlotte-Gastonia-Rock Hill Area Maintenance Plan for the 2008 8-Hour Ozone NAAQS

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R04-OAR-2024-0558; FRL-12961-01-R4]</DEPDOC> <SUBJECT>Air Plan Approval; South Carolina; Charlotte-Gastonia-Rock Hill Area Maintenance Plan for the 2008 8-Hour Ozone NAAQS</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> On September 26, 2023, the State of South Carolina, through the South Carolina Department of Environmental Services (SCDES, formerly the “South Carolina Department of Health and Environmental Control”), submitted a request for the Environmental Protection Agency (EPA) to approve a State Implementation Plan (SIP) revision containing the State's plan for maintaining the 2008 ozone National Ambient Air Quality Standard (NAAQS or standard) through 2036 for the South Carolina portion of the bi-state Charlotte-Rock Hill, North Carolina-South Carolina 2008 8-hour ozone nonattainment area (the entire area is hereinafter referred to as the “bi-State Charlotte Area” and the South Carolina portion is hereinafter referred to as the “York County Area”). EPA is proposing to approve and incorporate this maintenance plan, including the 2018 and 2036 motor vehicle emission budgets (budgets) for nitrogen oxides (NOx) and volatile organic compounds (VOC) for the York County Area, into the SIP. EPA is also notifying the public of the status of EPA's adequacy determination for the budgets for the York County Area. </SUM> <DATES> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before October 6, 2025. </DATES> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R04-OAR-2024-0558 at <E T="03">regulations.gov</E> . Follow the online instructions for submitting comments. Once submitted, comments cannot be edited or removed from <E T="03">Regulations.gov</E> . 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 ( <E T="03">i.e.,</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 <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets.</E> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Nelsha Athauda, 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)-562-9360. Ms. Athauda can also be reached via electronic mail at <E T="03">Athauda.Nelsha@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Summary of EPA's Proposed Action</FP> <FP SOURCE="FP-2">II. Background</FP> <FP SOURCE="FP-2">III. EPA's Evaluation of South Carolina's SIP Submittal</FP> <FP SOURCE="FP1-2">A. Attainment Emissions Inventory</FP> <FP SOURCE="FP1-2">B. Maintenance Demonstration</FP> <FP SOURCE="FP1-2">C. Monitoring Network</FP> <FP SOURCE="FP1-2">D. Verification of Continued Attainment</FP> <FP SOURCE="FP1-2">E. Contingency Plan</FP> <FP SOURCE="FP-2">IV. EPA's Analysis of South Carolina's Proposed NOx and VOC Budgets</FP> <FP SOURCE="FP-2">V. EPA's Adequacy Determination for the Proposed NOx and VOC Budgets</FP> <FP SOURCE="FP-2">VI. Effect of EPA's Proposed Action</FP> <FP SOURCE="FP-2">VII. Proposed Action</FP> <FP SOURCE="FP-2">VIII. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. Summary of EPA's Proposed Action</HD> In accordance with the Clean Air Act, 42 U.S.C. 7401, <E T="03">et seq.</E> (CAA or Act), EPA is proposing to approve the York County Area's maintenance plan for the 2008 8-hour ozone NAAQS, adopted by SCDES  <SU>1</SU> <FTREF/> on September 26, 2023, and submitted by SCDES as a revision to the South Carolina SIP on September 26, 2023. <SU>2</SU> <FTREF/> <FTNT> <SU>1</SU>  On July 1, 2024, SCDES was restructured into a health agency, the Department of Public Health, and an environmental agency, the Department of Environmental Services (DES). In a letter dated June 20, 2024, South Carolina represented to EPA that all the functions, powers, and duties of the environmental divisions, offices, and programs of the South Carolina Department of Health and Environmental Control (SCDHEC), including the authority to administer and enforce state implementation plans, are retained and continued in full force and effect under DES. This letter is in the docket for this proposed rulemaking. Throughout this proposal, the terms, “Department”, “South Carolina Department of Health and Environmental Services”, “SCDHEC”, “South Carolina Department of Environmental Services”, and “SCDES” are interchangeable. </FTNT> <FTNT> <SU>2</SU>  The September 26, 2023, SIP submission, with exception of the supporting modeling files, is included in the docket for this action. Due to size and compatibility limitations of the Federal Docket Management System, the supporting modeling files are instead available at the EPA Region 4 office. To request these files, please contact the person listed in this Notice of Proposed Rulemaking (NPRM) under the section titled <E T="02">FOR FURTHER INFORMATION CONTACT</E> . </FTNT> The York County Area's maintenance plan for the 2008 8-hour ozone NAAQS, submitted by SCDES on September 26, 2023, is designed to maintain the 2008 8-hour ozone NAAQS within the York County Area through the end of the second 10-year portion of the maintenance period beyond redesignation (through 2036). EPA is proposing to approve the plan because it meets all applicable requirements under CAA sections 110 and 175A. EPA is also proposing to approve the 2018 and 2036 NOx and VOC budgets in the York County Area second maintenance plan because they meet the applicable transportation conformity requirements under 40 CFR 93.118(e). <HD SOURCE="HD1">II. Background</HD> On March 12, 2008, EPA promulgated a revised 8-hour ozone NAAQS of 0.075 parts per million (ppm). <E T="03">See</E> 73 FR 16436 (March 27, 2008). Under EPA's regulations at 40 CFR part 50, the 2008 8-hour ozone NAAQS is attained when the 3-year average of the annual fourth highest daily maximum 8-hour average ambient air quality ozone concentrations is less than or equal to 0.075 ppm. <E T="03">See</E> 40 CFR 50.15. Ambient air quality monitoring data for the 3-year period must meet a data completeness requirement. The ambient air quality monitoring data completeness requirement is met when the average percent of days with valid ambient monitoring data is greater than 90 percent, and no single year has less than 75 percent data completeness as determined in Appendix I of part 50. Upon promulgation of a new or revised NAAQS, the CAA requires EPA to designate as nonattainment any area that is violating the NAAQS, based on the three most recent years of complete, quality assured, and certified ambient air quality data at the conclusion of the designation process. The bi-state Charlotte Area was designated marginal nonattainment for the 2008 8-hour ozone NAAQS on May 21, 2012, (effective July 20, 2012) using 2009-2011 ambient air quality data. <E T="03">See</E> 77 FR 30088 (May 21, 2012). The Area attained the standard, and on April 17, 2015, SCDES submitted a redesignation request and the first 10-year maintenance plan for the York County Area. In the final implementation rule for the 2008 8-hour ozone NAAQS (SIP Implementation Rule), EPA established ozone nonattainment area attainment dates based on Table 1 of section 181(a) of the CAA. <E T="03">See</E> 80 FR 12264 (March 6, 2015). This rule established an attainment date three years after the July 20, 2012, effective date for areas classified as marginal areas for the 2008 8-hour ozone nonattainment designations. Therefore, the bi-state Charlotte Area's attainment date was July 20, 2015. In 2015, the York County Area was redesignated to attainment for the 2008 8-hour ozone NAAQS, the 10-year maintenance plan was approved, and the public was notified that EPA found the NOx and VOC budgets adequate. <E T="03">See</E> 80 FR 76865 (December 11, 2015). The primary guidance on maintenance plans and redesignation requests is the September 4, 1992, memorandum from John Calcagni, titled “Procedures for Processing Requests to Redesignate Areas to Attainment” (“Calcagni Memorandum”). <SU>3</SU> <FTREF/> The Calcagni Memorandum outlines the key elements of a maintenance plan, which include the following: attainment emissions inventory, maintenance demonstration, monitoring network requirements, verification of continued attainment, and contingency plan elements. <FTNT> <SU>3</SU>  “Procedures for Processing Requests to Redesignate Areas to Attainment,” Memorandum from John Calcagni, Director, Air Quality Management Division, September 4, 1992 (hereinafter referred to as the “Calcagni Memorandum”), available at <E T="03">https://www.epa.gov/ground-level-ozone-pollution/procedures-processing-requests-redesignate-areas-attainment.</E> </FTNT> On April 17, 2015, SCDES requested that EPA redesignate the South Carolina portion of the bi-state Charlotte Area to attainment for the 2008 8-hour o ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 51k characters. 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