COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION NOTICE OF SIGNIFICANT MODIFICATION TO TITLE V OPERATING PERMIT

COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF ENVIRONMENTAL PROTECTION NOTICE OF SIGNIFICANT MODIFICATION TO TITLE V OPERATING PERMIT Notice is hereby given in accordance with 25 Pa. Code §§ 127.521 and 127.542 that United States Steel Corporation (USS) has submitted a significant operating permit modification application to the Pennsylvania Department of Environmental Protection (DEP) to modify Title V Operating Permit (TVOP) No. 09-00006 for its Fairless Hills facility (hereinafter referred to as "USS Fairless"), which is located at 400 Middle Drive in Falls Township, Bucks County. The modification incorporates Reasonably Available Control Technology (RACT) III requirements into the current TVOP in accordance with 25 Pa. Code § 129.114(a) (relating to alternative RACT proposal). The RACT III alternative compliance plan incorporates provisions and requirements for the control of emissions of nitrogen oxides (NOx) from a natural gas-fired galvanizing line furnace, rated at 68 mmBtu/hr heat input, at USS Fairless. Because USS Fairless is a major NOx emitting facility that commenced operation on or before August 3, 2018 [25 Pa. Code § 129.111(a) and (e)], and the galvanizing line furnace cannot meet any of the applicable presumptive RACT requirements or RACT emission limitations specified in 25 Pa. Code § 129.112(b)–(k) without the installation of an air cleaning device [25 Pa. Code § 129.114(a)], USS Fairless submitted an alternative RACT proposal for the galvanizing line furnace in accordance with 25 Pa. Code § 129.114(d). In its alternative RACT proposal, USS Fairless evaluated all potentially applicable add-on air cleaning devices for the control of NOx emissions from the galvanizing line furnace and determined that none were both technologically and economically feasible. Rather, USS Fairless proposed to continue to employ good combustion practices for the galvanizing line furnace (including the requirements in the current TVOP to operate and maintain the galvanizing line furnace in accordance with the manufacturers' specifications and to perform an adjustment or tuneup on an annual basis) as RACT. As such, the RACT III alternative compliance plan does not include any new sources or air cleaning devices or emissions increases. The provisions and requirements in the RACT III alternative compliance plan are intended to address the Commonwealth's RACT obligations under section 184 of the Clean Air Act for the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS). The RACT III alternative compliance plan does not adopt any new regulations. If approved by DEP, the RACT III alternative compliance plan will be submitted to the United States Environmental Protection Agency (EPA) as a revision to the Commonwealth's State Implementation Plan (SIP). Requirements that are not part of the RACT III alternative compliance plan will be excluded from the SIP revision submittal. The provisions and requirements in the RACT III alternative compliance plan for USS Fairless that are proposed to be submitted to EPA as a revision to the Commonwealth's SIP are found in Condition # 020, Section C, of the proposed TVOP, and Condition #s 006, 009, and 011, Section D (under Source ID 420), of the proposed TVOP. Pursuant to 25 Pa. Code § 129.114(j)(2), a public comment period will begin on November 1, 2025, for the submission of written comments, suggestions, objections, or other information regarding the RACT III alternative compliance plan. Submissions may be made in writing to, Pennsylvania Department of Environmental Protection, Southeast Regional Office, Janine Tulloch-Reid, P.E., 2 East Main Street, Norristown, PA 19401, or electronically at RA-EPSEROAQPUBCOM@pa.gov. Each written submission must contain the name, address, and telephone number of the person(s) submitting the comments; identification of the RACT III alternative compliance plan, including the permit number; and a concise statement regarding the RACT III alternative compliance plan provision or requirement that the person is commenting on and the relevancy of the information or objections to issuance of the RACT III alternative compliance plan. A public hearing is scheduled for Tuesday, December 2, 2025, from 11:00 AM–12:00 PM, at DEP's Southeast Regional Office, 2 East Main Street, Norristown, PA 19401, to accept oral and written testimony on the proposed RACT III alternative compliance plan action and the proposed SIP revision. Persons wishing to present testimony at the public hearing are asked to register with Robyn Briggs, Regional Communications Manager for DEP's Southeast Region, at robbriggs@pa.gov or 484.250.5965. Speakers must pre-register in order to testify at the hearing. Registration to testify will close at 5:00 PM on Tuesday, November 25, 2025. Oral testimony at the public hearing will be limited to a maximum of 5 minutes per individual. Each organization is requested to designate one witness to present testimony on its behalf and time may not be relinquished to others. Persons unable to attend the public hearing may submit a written statement and exhibits to DEP, in the same manner as specified above, within 10 days after the public hearing. All comments, whether submitted to DEP in writing or delivered orally at the public hearing, shall merit equal consideration. Therefore, the public comment period will open on November 1, 2025, and remain open through December 12, 2025. Copies of the significant modification application, proposed RACT III alternative compliance plan, and other relevant information are available for public review online at the above web address or at DEP's Southeast Regional Office, 2 East Main Street, Norristown, PA 19401. An appointment to review the documents at DEP's Southeast Regional Office may be scheduled by contacting the Records Management Section of DEP at 484.250.5910 between 8:00 AM–4:00 PM, Monday–Friday, except holidays. October 29, 30, 31 2025 LSOM0396421