Document 5bwV0LgmMYVXB2kXJZwrqQ168

Request for Extension of Compliance SECTION 1 GENERAL INFORMATION A. Print or type the following information for each facility for which you are requesting an extension of compliance (63.9(b)(2)(i)-(ii)) Operating Permit Number (OPTIONAL) Facility 1.D. Number (OPTIONAL) Permits 2814-V5, 2421-V10, 476-V9, and 1909-V3 Responsible Official's Name/Title Nattaya Boonsombat/Responsible Care Leader Street Address 355 Highway 3142 CilY Hahnville Stale Louisiana ZIP Code 70057 Facility Name (if different from Responsible Official's Name) St. Charles Operations Facility Street Address (If different than Responsible Official's Street Address) Facility Local Contact Name Tom Nichols City Hahnville Title EH&S Leveraged Air Specialist State Louisiana Phone (OPTIONAL 1-985-783-3250 ZIP Code 70057-0059 B. Indicate the relevant standard or other requirement that is the basis for this request for this compliance extension request Pursuant to 40 CFR 63.6(0(4)(i) and (ii) of the MACT rule General Provisions our St, Charles Operations site is requesting a one-year extension from the compliance date of July 15, 2026, to July 15, 2027, for the following projects and associated regulatory citations: Project #1 -- Dow is changing this project from a Thermal Oxidizer to a Flare - 40 CFR 63 Subpart G -- 40 CFR 63.108 and 63.124 -- Process Vents that are in ethylene oxide service -- procedures to determine compliance. Project #2 -- Purge Glycol Reactor Project - 40 CFR 63 Subpart G 40 CFR 63.138 -- Process wastewater provisions -- performance standards for treatment processes managing Group 1 wastewater streams and/or residuals removed from Group 1 wastewater streams; and 40 CFR 63.138(b)(3) -- Control options: Group 1 wastewater streams for Table 9 compounds -- Reduce, by removal or destruction, the concentration of ethylene oxide to a level less than 1 parts per million by weight as determined in the procedures in Page 1 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000046-00008 SC_EVERSPLIT0020557 63.145(b) of this subpart; and the following general control provisions for Group 1 process wastewater streams: 40 CFR 63.132 -- Process wastewater provisions -- general 40 CFR 63.133 -- Process wastewater provisions -- wastewater tanks 40 CFR 63.134 -- Process wastewater provisions -- surface impoundments 40 CFR 63.135 -- Process wastewater provisions -- containers 40 CFR 63.136 -- Process wastewater provisions -- individual drain systems 40 CFR 63.137 -- Process wastewater provisions -- oil-water separators Project #3 -- Dow is removing this project from the extension request. Revised Emission Control System for Start-up Vents - 40 CFR 63 Subpart G - 40 CFR 63.124 P-r-oeess-VeRts-and Stor-age-V-essek that are in ethylene oxide service procedures to determine compliance. Reasons why additional time is needed A one-year extension is needed in order to properly engineer and construct these projects. Typically, it takes 36 months to complete projects similar to these. Key steps in the engineering, procurement, and construction process are: Major Steps in Process Testing to determine "In EO Service" and PreFEED Project Scoping Front End Engineering Design (FEED) Detailed Design Engineering Procurement (Obtaining Vendor Bids, Vendor Questions & Selection, Equipment Fabrication & Delivery to site) Construction of Required Equipment, Piping and Instrumentation Develop Operating Procedures, Commissioning Equipment, and Placing Into Service Estimated Time to Complete (Months) 6 12 9 19 (overlaps with engineering) 10 (overlaps with detailed engineering) 1 -- 1.5 months Total Estimated Time for Project including testing 36 to determine "In EO Service": Note: Some steps like Procurement overlap with Front End Engineering Design, Detailed Design Engineering, and Construction. Construction also overlaps with Detailed Design Engineering Page 2 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000046-00009 SC_EVERSPLIT0020558 SECTION II CERTIFICATION (Note: you may edit the text in this section as deemed appropriate) Based upon information and belief formed after a reasonable inquiry, t, as a responsible official of the above-mentioned facility, certify the information contained in this request is accurate and true to the best of my knowledge. Name of Responsible Official (Print or Type) Nattaya Boonsombat Signature of Responsible Official 1\1&01--cel Title Responsible Care Leader Date (mm/dd/yy) G2/1.0/ 25 Note: Responsible official is defined under 53.2 as any of the following: the president, vicepresident, secretary, or treasurer of the company that owns the plant; the owner of the plant; the plant engineer or supervisor; a government official if the plant is owned by the Federal, State, city, or county government; or a ranking military officer if the plant is located on a military installation. SECTION III COMPLIANCE SCHEDULE INFORMATION A. Describe the controls that will be installed at your facility to ensure compliance with the relevant standard. (63.6(i)(6)(i)(A)) -- See the descriptions for each project below: Page 3 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000046-00010 SC_EVERSPLIT0020559 Project #1 -- Dow is changing this project from a thermal oxidizer to a flare. An existing flare system will be recommissioned and repurposed to collect and control any process vents in Ethylene Oxide service from the Methyl Glycol Ethers Plant and the Higher Glycols Plant. The existing system will be instrumented to comply with the monitoring requirements for flares, and a new stand-alone flare stack will be constructed. There are some small process vents from these two HON covered plants that have minimal ethylene oxide emissions, but each process vent stream with 1 ppmv or more ethylene oxide must be controlled. Project #2 -- Installation of a process wastewater reactor system, called a Purge Glycol Reactor, to react small concentrations of ethylene oxide in process wastewater streams from the Oxide Plant and Site Logistics Area, Methyl Glycol Ethers Plant, and the Higher Glycols Plant to other chemical compounds. The reactor system will be operated at an elevated temperature and pressure to react low concentrations of ethylene oxide to other organic compounds. These small process wastewater streams from these three HON covered process units have minimal ethylene oxide emissions, but each process wastewater stream with 1 ppmw or more ethylene oxide must be controlled. Project #3 -- Dow is removing this project from the extension request. Due to small levels of emissions associated with these sources, the health of persons will be protected from imminent endangerment, as required by 40 CFR 63.6(i)(4)(ii). B. Describe your compliance schedule by specifying the date by which you will complete each of the following steps toward achieving compliance: (63.6(i)(6)(i)(B)(1)-(4)): A compliance schedule, including the date by which each step toward compliance will be reached. At a minimum, the list of dates shall include: (1)The date by which on-site construction, installation of emission control equipment, or a process change is planned to be initiated. On-site construction for these projects is planned to be initiated by August 1, 2026. (2) The date by which final compliance is to be achieved. Compliance for these projects is expected to be achieved by July 15, 2027. Page 4 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000046-00011 SC_EVERSPLIT0020560 (3) The date by which on-site construction, installation of emission control equipment, or a process change is to be completed; and On-site construction is planned to be completed by June 1, 2027, for these projects. (4) The date by which final compliance is to be achieved; Start-up of these systems and compliance is expected to be achieved by July 15, 2027. Page 5 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000046-00012 SC_EVERSPLIT0020561