Air Plan Approval; IA, Muscatine; 2010 1-Hour SO2 Maintenance Plan and Redesignation

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Parts 52 and 81</CFR> <DEPDOC>[EPA-R07-OAR-2025-0818; FRL-12901-02-R7]</DEPDOC> <SUBJECT> Air Plan Approval; IA, Muscatine; 2010 1-Hour SO <E T="0735">2</E> Maintenance Plan and Redesignation </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 taking final action to redesignate the nonattainment area in Muscatine County, Iowa to attainment for the 2010 1-hour sulfur dioxide (SO <E T="52">2</E> ) National Ambient Air Quality Standard (NAAQS). The EPA is also approving Iowa's maintenance plan for the 2010 1-hour SO <E T="52">2</E> NAAQS for the Muscatine nonattainment area and approving modifications to source-specific permits in the Iowa State Implementation Plan (SIP). The EPA is taking this action in accordance with the requirements of the Clean Air Act (CAA). </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This final rule is effective on December 18, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-R07-OAR-2025-0818. All documents in the docket are listed on the <E T="03">https://www.regulations.gov</E> website. Although listed in the index, some information is not publicly available, <E T="03">i.e.,</E> Confidential Business Information (CBI) 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 through <E T="03">https://www.regulations.gov</E> or please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section for additional information. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Bethany Olson, Environmental Protection Agency, Region 7 Office, Air Quality Planning Branch, 11201 Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-7905; email address: <E T="03">olson.bethany@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” and “our” refer to EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. What is being addressed in this document?</FP> <FP SOURCE="FP-2">II. Background</FP> <FP SOURCE="FP-2">III. Have the requirements for approval of a SIP revision been met?</FP> <FP SOURCE="FP-2">IV. What action is the EPA taking?</FP> <FP SOURCE="FP-2">V. Incorporation by Reference</FP> <FP SOURCE="FP-2">VI. Statutory and Executive Order Reviews</FP> </EXTRACT> <HD SOURCE="HD1">I. What is being addressed in this document?</HD> The EPA is taking final action to approve a SIP revision and redesignation request submitted on November 17, 2021, by the Iowa Department of Natural Resources (IDNR). The EPA is taking the following three separate but related actions: (1) to add new or revised permits for Muscatine area sources into the Iowa SIP and remove certain air construction permits from the SIP; (2) to approve Iowa's maintenance plan for the 2010 1-hour SO <E T="52">2</E> NAAQS in the Muscatine area and incorporate it into the SIP; and (3) to redesignate the Muscatine area to attainment for the 2010 1-hour SO <E T="52">2</E> NAAQS. The EPA finds that the State's submittal meets the requirements for redesignation under the CAA and the revisions do not interfere with any applicable requirement concerning attainment and reasonable further progress. The full State submission is included in the docket for this action. <HD SOURCE="HD1">II. Background</HD> On June 2, 2010 (75 FR 35520), the EPA signed the revised the primary SO <E T="52">2</E> NAAQS, establishing a new 1-hour standard of 75 parts per billion (ppb). Following promulgation of a new or revised NAAQS, the EPA is required by CAA section 107(d) to designate areas throughout the nation as attaining or not attaining the NAAQS, or as unclassifiable. On August 5, 2013, the EPA designated a portion of Muscatine County, Iowa, as nonattainment for the 2010 primary 1-hour SO <E T="52">2</E> NAAQS (78 FR 47191), effective October 4, 2013. Iowa submitted an attainment plan for the Muscatine area on May 26, 2016. Iowa's approved 2016 attainment plan provided a modeled attainment demonstration and the required nonattainment planning requirements for the Muscatine NAA. The attainment plan included permit conditions to reduce SO <E T="52">2</E> emissions at three facilities in the NAA: Grain Processing Corporation (GPC), Muscatine Power and Water (MPW), and Monsanto Company—Muscatine (Monsanto), now Bayer CropScience LP. <SU>1</SU> <FTREF/> The conditions are contained in air construction permits issued by IDNR and were approved into the SIP as part of the attainment plan approval. <SU>2</SU> <FTREF/> The EPA issued a final approval of Iowa's attainment plan on November 17, 2020 (85 FR 73218). <FTNT> <SU>1</SU>  The Monsanto facility in Muscatine is now under the ownership of Bayer CropScience LP. This document retains use of the Monsanto name for consistency with the Iowa submittal. Bayer CropScience L.P. assumed all construction permits for Monsanto that are relevant to this action. </FTNT> <FTNT> <SU>2</SU>  85 FR 73218, November 17, 2020. </FTNT> On November 17, 2021, Iowa submitted a redesignation request and maintenance plan for the Muscatine nonattainment area for the 2010 SO <E T="52">2</E> NAAQS. The submission also included modifications to SIP-approved permits for GPC, MPW, and Monsanto. The submitted permit revisions replace some specific conditions that the EPA had previously approved into the SIP for the purpose of demonstrating attainment of the SO <E T="52">2</E> standard pursuant to the nonattainment requirements of sections 172, 191, and 192 of the CAA. On January 26, 2022, the EPA proposed to determine that the Muscatine NAA attained the 2010 1-hour SO <E T="52">2</E> NAAQS by the applicable attainment date of October 4, 2018 (87 FR 3958). The EPA issued a final determination of attainment by the attainment date for the 2010 1-hour SO <E T="52">2</E> NAAQS on April 7, 2022 (87 FR 20329). On August 21, 2025 (90 FR 40797), the EPA proposed to approve Iowa's 2021 redesignation request and maintenance plan for the Muscatine area for the 2010 SO <E T="52">2</E> NAAQS. An explanation of the CAA requirements, a detailed analysis of the revisions, and EPA's reasons for proposing approval were provided in the notice of proposed rulemaking (NPRM) and will not be restated here. The EPA also proposed to approve revisions to SIP-approved permits. The submitted revisions remove outdated permits, add new permits, and modify SIP-approved permits. The air construction permits include reasonably available control technology (RACT) limits for the 2010 1-hour SO <E T="52">2</E> NAAQS, compliance monitoring, and recordkeeping and reporting requirements at GPC, MPW, and Monsanto. The emission limits establish the maximum permitted allowable emission rate for each emission point, and Iowa provided updated dispersion modeling in its 2021 SIP submission based on these conditions. The new and modified permits are contained in Attachments 1 through 3 of the State submittal in the docket for this action. The requested permit revisions are as follows: • Remove twelve GPC permits relied upon in the 2016 attainment plan for emission points (stacks) no longer in service. The GPC permit numbers are 15-A-078, 79-A-194-S2, 74-A-014-S1, 74-A-015-S2, 79-A-195-S2, 71-A-067-S4, 15-A-202, 15-A-209, 11-A-338-S1, 15-A-354, 05-A-926-S4, 75-A-087-S1. • Remove eight permits from the SIP due to the revocation of the 24-hour and annual primary SO <E T="52">2</E> NAAQS. The numbers are GPC permits 74-A-015-S, 79-A-194-S, 79-A-195-S, and 95-A-374; MPW permits 74-A-175-S and 95-A-373; and Monsanto permits 76-A-161S3 and 76-A-265S3. • Add five new GPC permits into the SIP containing SO <E T="52">2</E> RACT limits for the 2010 1-hour SO <E T="52">2</E> NAAQS. The new permits are for four new stacks and one newly identified SO <E T="52">2</E> emission source. The GPC permit numbers are 17-A-298, 17-A-299, 17-A-112, 19-A-515-S1, and 18-A-136. • Replace twenty GPC permits, two MPW permits, and one Monsanto permit in the Iowa SIP that were relied upon in the 2016 attainment plan. Several revisions to GPC permits establish a Collection of Air Permits (CAP) which is a type of air construction permit issued by IDNR that combines the requirements and conditions for multiple emission points (and thus multiple permit numbers) into one document. Other revisions included changes to SO <E T="52">2</E> RACT limits or updates unrelated to SO <E T="52">2</E> . The modified GPC permit numbers are CAP: 80-A-149-S6, CAP: 80-A-150-S6, CAP: 85-A-031-S5, CAP: 85-A-032-S5, 91-A-068-S3, 92-A-383-S3, 92-A-385-S2, CAP: 94-A-055-S3, CAP: 94-A-061-S3, 02-A-781-S3, 02-A-782-S3, 10-A-563-S2, 15-A-200-S1, 15-A-201-S1, 15-A-213-S2, 15-A-486-S1, 15-A-326-S1, 03-A-471-S3, 06-A-1261-S2, and 15-A-199-S1. The modified MPW permits are 95-A-373-P4 and 80-A-191-P4, and the Monsanto permit is 82-A-092-P12. The EPA's NPRM and supporting information contained in the docket were made available for public comment from August 21, 2025, to September 22, 2025. EPA received no comments on the proposal. Therefore, we are finalizing our action as proposed. <HD SOURCE="HD1">III. Have the requirements for approval of a SIP revision been met?</HD> The State's submission has met the public notice requirements for SIP submissions in accordance with 40 CFR 51.102. The submission also satisfied the completeness criteria of 40 CFR part 51, a ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 34k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━