Approval of the Clean Air Act, Section 112(l), Authority for Hazardous Air Pollutants; State of Connecticut Department of Energy and Environmental Protection; Approval of the Clean Air Act Section 502, State Operating Permit Programs, State of Connecticut Department of Energy and Environmental Protection

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Parts 63 and 70</CFR> <DEPDOC>[EPA-R01-OAR-2025-0655; FRL-12924-01-R1]</DEPDOC> <SUBJECT>Approval of the Clean Air Act, Section 112(l), Authority for Hazardous Air Pollutants; State of Connecticut Department of Energy and Environmental Protection; Approval of the Clean Air Act Section 502, State Operating Permit Programs, State of Connecticut Department of Energy and Environmental Protection</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 approve regulatory amendments that revise two previous program approvals from the Connecticut Department of Energy and Environmental Protection (CT DEEP). The revisions include amendments to the Regulations of Connecticut State Agencies (RCSA) that revise the Connecticut State Operating Permit Program and amendments to RCSA that revise limitations on potential to emit Clean Air Act (CAA) pollutants. A significant aspect of this action involves revising the definition of “hazardous air pollutant” in the RCSA in response to EPA adding 1-bromopropane to the list of hazardous air pollutants. This action is being taken under the Clean Air Act. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Written comments must be received on or before September 29, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> Submit your comments, identified by Docket ID No. EPA-R01-OAR-2025-0655 at <E T="03">https://www.regulations.gov,</E> or via email to <E T="03">numrich.liam@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 <E T="03">Regulations.gov</E> . For either manner of submission, 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, 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 or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets</E> . Publicly available docket materials are available at <E T="03">https://www.regulations.gov</E> or at the U.S. Environmental Protection Agency, EPA Region 1 Regional Office, Air and Radiation Division, 5 Post Office Square—Suite 100, Boston, MA. EPA requests that if at all possible, you contact the contact listed in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section to schedule your inspection. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Liam Numrich, Air Permits, Toxics, and Indoor Programs Branch, U.S. Environmental Protection Agency, EPA New England Regional Office, 5 Post Office Square—Suite 100, (Mail code 5-MI), Boston, MA 02109-3912, telephone number 617-918-1307, <E T="03">numrich.liam@epa.gov</E> . </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document whenever “we,” “us,” or “our” is used, we mean EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Background and Purpose</FP> <FP SOURCE="FP-2">II. Review of Connecticut State Operating Permit Program Revisions and Amendments to Air Quality Regulations</FP> <FP SOURCE="FP-2">III. EPA's Analysis of CT DEEP's Title V Program Revisions and 112(l) State Program Revisions</FP> <FP SOURCE="FP-2">IV. Proposed Action</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. Background and Purpose</HD> The Clean Air Act Amendments of 1990 required all state and local permitting authorities to develop operating permit programs that meet certain federal criteria. (42 U.S.C. 7661-7661e.) In implementing the operating permit programs, the permitting authorities require certain sources of air pollution to obtain permits that contain all applicable requirements under the CAA. The focus of the operating permit program is to improve compliance and enforcement by issuing each source a permit that consolidates all of the applicable CAA requirements into a federally enforceable document. By consolidating all of the applicable requirements, the source, the public, and the permitting authorities can more easily determine what CAA requirements apply and how to determine compliance with those requirements. Sources required to obtain an operating permit under this program include “major” sources of air pollution and certain other sources specified in the CAA or in EPA's implementing regulations. (See 40 CFR 70.3.) For example, all sources regulated under the acid rain program, regardless of size, must obtain operating permits. (See 40 CFR 72.30.) Examples of major sources include: those that have the potential to emit 100 tons per year or more of volatile organic compounds, carbon monoxide, lead, sulfur dioxide, nitrogen oxides, or particulate matter (PM 10); those that emit 10 tons per year of any single hazardous air pollutant (HAP); or those that emit 25 tons per year or more of a combination of HAPs. (40 CFR 70.2.) In areas that are not meeting the National Ambient Air Quality Standards for ozone, carbon monoxide, or particulate matter, major sources are defined by the gravity of the nonattainment classification. ( <E T="03">Id.</E> ) The Connecticut State Operating Permit Program's initial approval became effective on May 31, 2002. (67 FR 31966.) Section 112(b) of the CAA established a list of 189 HAP. This provision of the CAA also provides the EPA with the authority to modify the list. In response to a petition to the Administrator to list 1-bromopropane or 1-BP (also known as n-propyl bromide (nPB)), the EPA, for the first time, added a new HAP to the CAA section 112(b) HAP list (HAP list) on January 5, 2022. (87 FR 393.) This new addition to the HAP list prompted updates to Connecticut's definition of “hazardous air pollutant” in the RSCA in order to keep Connecticut's regulations consistent with listing or delisting chemical compounds from the federal HAP list. The Administrator may, under the authority of section 112(l) and 40 CFR 63.91, approve a State program designed to establish limits on the potential to emit HAP listed pursuant to section 112 of the CAA. Any request for approval under this subpart shall meet all section 112(l) approval criteria specified by the otherwise applicable Federal section 112 rule, emission standard, or requirement. Approval of the rule delegates to the State the authority to implement and enforce the approved rule in lieu of the otherwise applicable Federal section 112 rule. CT DEEP's 112(l) program was approved on April 11, 2022. On June 14, 2024, CT DEEP submitted revisions to its State Operating Permit Program and to its Approved Limitations on Potential to Emit CAA Section 112 pollutants to EPA. These amendments revise two previous program approvals for EPA's approval. They consist of (1) amendments to sections 22a-174-1 (Definitions) and 22a-174-33 (Title V sources) of the RCSA that revise the Connecticut State Operating Permit Program; and (2) amendments to RCSA sections 22a-174-1, 22a-174-33a (Limit on Premises-Wide Actual Emissions Below 50% of Title V Source Thresholds), and 22a-174-33b (Limit on Premises-Wide Actual Emissions Below 80% of Title V Source Thresholds) that revise limitations on potential to emit CAA section 112 pollutants for the state's CAA section 112(l) state program to limit the potential to emit HAP pollutants below Title V source thresholds. <HD SOURCE="HD1">II. Review of Connecticut State Operating Permit Program Revisions and Amendments to Air Quality Regulations</HD> In accordance with Title V program revisions required at 40 CFR 70.4(i)(2) and CAA 112(l) state program revision requirements at 40 CFR 63.91, the primary change in CT DEEP's June 14, 2024, submittal is a new definition of “hazardous air pollutant” in RCSA section 22a-174-1. The current definition of “hazardous air pollutant” is deleted and replaced with the following: `Hazardous air pollutant,' `Federal hazardous air pollutant' or `HAP,' except as otherwise provided in section 22a-174-29 of the Regulations of Connecticut State Agencies, means any air pollutant listed in section 112(b)(1) of the Act, inclusive of deletions and additions set out in 40 CFR part 63, subpart C, as may be amended from time to time.” This new definition is consistent with EPA's most recent change to the federal definition of HAP to include 1-bromopropane in the list of HAP established under the CAA section 112 program. The new definition also incorporates future changes to the federal definition resulting from EPA's listing or delisting of a chemical compound. CT DEEP submitted companion changes to RCSA section 22a-174-33a(a)(4) and RCSA section 22a-174-33b(a)(10) to effectuate the change in the definition of “hazardous air pollutant” at RCSA section 22a-174-1 into those two regulations as they regulate HAP emissions as a CAA section 112(l) state program. In addition to this change, there are a number of revisions to CT DEEP's Title V operating permit program at RCSA section 22a-174-3 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 16k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━