Air Plan Approval; Missouri; Control of Sulfur Dioxide Emissions and Approval and Promulgation of State Plan (Negative Declaration) for Designated Facilities and Pollutants

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Parts 52 and 62</CFR> <DEPDOC>[EPA-R07-OAR-2025-0263; FRL-12807-01-R7]</DEPDOC> <SUBJECT>Air Plan Approval; Missouri; Control of Sulfur Dioxide Emissions and Approval and Promulgation of State Plan (Negative Declaration) for Designated Facilities and Pollutants</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The EPA is proposing to approve revisions to the Missouri State Implementation Plan (SIP) submitted by the State of Missouri. Missouri requests that EPA approve replacing the previous statewide sulfur dioxide (SO <E T="52">2</E> ) rule in the SIP with the latest version of a newer SO <E T="52">2</E> rule (10 CSR 10-6.261). This action would result in a number of changes to the SIP, including removing outdated requirements as a result of facilities that have historically closed or switched from coal to lower sulfur fuels, as well as those that have become subject to more stringent SO <E T="52">2</E> requirements elsewhere in the Missouri SIP. Other revisions include reinstating SO <E T="52">2</E> emission limits for the Ameren-Labadie and Evergy-Hawthorn power plants that had been previously removed. The revisions do not impact the stringency of the SIP, nor do they impact the state's ability to attain or maintain the National Ambient Air Quality Standards (NAAQS). In conjunction with proposing approval of revisions to the Missouri SIP, the EPA is proposing to approve Missouri's negative declaration of sources subject to sulfuric acid production requirements submitted by the MoDNR to the EPA on May 4, 2022. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before July 28, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> You may send comments, identified by Docket ID No. EPA-R07-OAR-2025-0263 to <E T="03">https://www.regulations.gov.</E> Follow the online instructions for submitting comments. <E T="03">Instructions:</E> All submissions received must include the Docket ID No. EPA-R07-OAR-2025-0263 for this rulemaking. Comments received will be posted without change to <E T="03">www.regulations.gov,</E> including any personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the “Written Comments” heading of the <E T="02">SUPPLEMENTARY INFORMATION</E> section of this preamble. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Wendy Vit, Environmental Protection Agency, Region 7 Office, Air—Analysis, Grants, Partnership Programs, 11201 Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-7697; email address: <E T="03">vit.wendy@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” and “our” refer to the EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Written Comments</FP> <FP SOURCE="FP-2">II. What is being addressed in this document?</FP> <FP SOURCE="FP-2">III. What is EPA's analysis of the rule revisions?</FP> <FP SOURCE="FP1-2">A. Exemption for Ultra Low Sulfur Diesel</FP> <FP SOURCE="FP1-2">B. Rule Provisions Linked to State's Historical CAA 111(d) Plan for Sulfuric Acid Production</FP> <FP SOURCE="FP1-2">C. Non-Named Indirect Heating Sources</FP> <FP SOURCE="FP1-2"> D. Facility-Specific SO <E T="52">2</E> Emission Limits </FP> <FP SOURCE="FP1-2"> 1. SO <E T="52">2</E> Emission Limits in 6.261 Table 1 </FP> <FP SOURCE="FP1-2"> 2. SO <E T="52">2</E> Emission Limits Not Included in Rule </FP> <FP SOURCE="FP1-2"> 3. Summary of EPA's Analysis of Revisions to Facility-specific SO <E T="52">2</E> Emission Limits </FP> <FP SOURCE="FP1-2">E. Reporting, Recordkeeping, and Testing Requirements</FP> <FP SOURCE="FP-2">IV. Negative Declaration for 111(d) Requirements for Sulfuric Acid Production</FP> <FP SOURCE="FP-2">V. Have the requirements for approval of a SIP revision been met?</FP> <FP SOURCE="FP-2">VI. What action is the EPA taking?</FP> <FP SOURCE="FP-2"> VII. Incorporation by Reference </FP> <FP SOURCE="FP-2">VIII. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. Written Comments</HD> Submit your comments, identified by Docket ID No. EPA-R07-OAR-2025-0263, at <E T="03">https://www.regulations.gov.</E> Once submitted, comments cannot be edited or removed from <E T="03">Regulations.gov</E> . The 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. The 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> <HD SOURCE="HD1">II. What is being addressed in this document?</HD> The EPA is proposing to approve revisions to the Missouri SIP received on April 23, 2025. In its submission, the MoDNR requested rescinding 10 CSR 10-6.260 “Restriction of Emission of Sulfur Compounds” and replacing it with a newer statewide regulation, 10 CSR 10-6.261 “Control of Sulfur Dioxide Emissions” (state effective date May 30, 2025) in the Missouri SIP. At the same time, we are proposing to approve Missouri's negative declaration pursuant to the state's approved Clean Air Act (CAA) 111(d) plan for Sulfuric Acid Mist from Existing Sulfuric Acid Production Plants, which is codified at 40 CFR 62.6353. The negative declaration is necessary for Missouri to remove portions of 10 CSR 10-6.260 that are linked to the state's 111(d) plan for sulfuric acid production. 10 CSR 10-6.260 was originally approved into the SIP at 40 CFR 52.1320(c) in 1998 (63 FR 45727, August 27, 1998) and has been revised in the SIP several times. <SU>1</SU> <FTREF/> A portion of 6.260, subsection (3)(A), was solely approved pursuant to the state's 111(d) plan for sulfuric acid production and has never been in the Missouri SIP. 10 CSR 10-6.261 was initially put in place in the Missouri Code of State Regulations (CSR) with an effective date of November 30, 2015, concurrent with the removal of 6.260 from the CSR. Although 6.261 has been revised several times in the Missouri CSR, it has never been approved into the Missouri SIP. On March 7, 2019, Missouri submitted the previous version of 6.261 (state effective date March 30, 2019) and requested that it replace 6.260 in the SIP. However, on January 4, 2023, the EPA finalized disapproval of the requested SIP revision because the state had not demonstrated that the removal of SO <E T="52">2</E> emission limits for the Hawthorn and Labadie power plants from the SIP would not interfere with NAAQS attainment and reasonable further progress (RFP), or any other applicable requirement of the CAA. <SU>2</SU> <FTREF/> Missouri subsequently revised 6.261 by restoring the Hawthorn and Labadie SO <E T="52">2</E> limits from 6.260, as well as making a number of other changes. This most recent revision of 6.261 with a state effective date May 30, 2025, was submitted to the EPA on April 23, 2025 and is the subject of this proposed approval action. Specifically, we are proposing to find that reinstating the Hawthorn and Labadie SO <E T="52">2</E> emission limits from 6.260 into 6.261 addresses the deficiencies identified in the EPA's January 4, 2023 disapproval action. In addition, we are proposing to approve replacing 6.260 with 6.261 in the Missouri SIP, as well as approve Missouri's negative declaration in lieu of the 111(d) plan for sulfuric acid production. <FTNT> <SU>1</SU>  See 71 FR 12623 (March 13, 2006), 73 FR 35071 (June 20, 2008), and 78 FR 69995 (November 22, 2013). </FTNT> <FTNT> <SU>2</SU>  See 88 FR 292 (January 4,2023). </FTNT> In order for the EPA to fully approve a SIP revision, the SIP revision must meet the requirements of CAA section 110(l), 42 U.S.C. 7410(l). Under CAA section 110(l), the EPA may not approve a SIP revision that would interfere with any applicable requirement concerning NAAQS attainment and Reasonable Further Progress (RFP), or any other applicable requirement of the CAA. Missouri submitted a CAA section 110(l) demonstration in support of their requested SIP revisions, which is included in the docket for this action. Our analysis of the key SIP revisions and Missouri's section 110(l) demonstration can be found in section III of this preamble. The EPA's technical support document (TSD) included in this docket provides greater detail. 10 CSR 10-6.261 contains SO <E T="52">2</E> emissions limits and requirements that were in place prior to the 2010 1-hour SO <E T="52">2</E> NAAQS; it does not include requirements relied on for meeting 2010 1-hour SO <E T="52">2</E> NAAQS requirements in the Missouri's nonattainment and maintenance areas that were previously approved into Missouri's SIP. <SU>3</SU> <FTREF/> <FTNT> <SU>3</SU>  Requirements to comply with the 2010 SO <E T="52">2</E> NAAQS in the state's maintenance areas are contained in SIP-approved consent agreements with Vicinity (formerly Veolia) and Ameren. Vicinity's consent agreement was approved into the SIP in conjunction with the redesignation of the Jackson County, Missouri SO <E T="52">2</E> nonattainment area (87 FR 48 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 41k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━