Document ZnLxeEeyavZx3q47BjGN5YpB0

July 29, 2025 TRANSMITTED VIA EMAIL Amanda Saijis, SEMS Coordinator Walter Oil & Gas Corporation 1100 Louisiana, Suite 200 Houston, Texas 77002 asaijas@walteroil.com Re: Notice of Potential Violation and Opportunity to Confer NPDES Permit: GMG290129 Dear Ms. Saijas: Information currently available to the United States Environmental Protection Agency, Region 6 (EPA) suggests that Walter Oil & Gas Corporation (Walter) may have committed violations of Section 301 of the Clean Water Act (CWA), 33 U.S.C. 1311 and National Pollution Discharge Elimination System (NPDES) General Permit for Offshore Activities (GMG290000) at the Permitted Features listed in the Enclosures. By this letter, EPA is extending to you an opportunity to advise EPA, via a conference call or in writing, of any information which EPA should consider with respect to the potential violations. Walter owns or operates facilities that discharge pollutants to the waters of the contiguous zone or the ocean under the permit, GMG290129. EPA identified the potential violations in a file review for the monitoring period of May 11, 2023 to May 31, 2025 and in a compliance evaluation inspection conducted by the United States Bureau of Safety and Environmental Enforcement (BSEE) on September 24, 2024. The potential violations are listed in Attachments contained herein. Within 15 calendar days of receipt of this letter, please indicate if you would like to discuss this matter by contacting Michael Blaha of my staff at (214) 665-8574 or blaha.michael@epa.gov. Sincerely, Bryant Smalley Chief Water Enforcement Branch Notice of Potential Violation and Opportunity to Confer NPDES Permit: GMG290129 Page 2 Enclosures Attachment A - Effluent Violations Attachment B - DMR Non-Receipt Violations Attachment C - BSEE Inspection Violations ec: Judy Triche, Chief, Environmental Monitoring Unit, BSEE judy.triche@bsee.gov Review Period: 05/11/2023 - 05/31/2025 Attachment A Environmental Protection Agency Integrated Compliance Information System (ICIS) Effluent Violations GMG290129 Monitoring Period End Date 02/28/2025 09/30/2024 09/30/2024 09/30/2024 06/30/2024 03/31/2024 01/31/2024 10/31/2023 10/31/2023 07/31/2023 Monitoring Period From 01/01/2025 to 03/31/2025 From 07/01/2024 to 09/30/2024 From 07/01/2024 to 09/30/2024 From 07/01/2024 to 09/30/2024 From 04/01/2024 to 06/30/2024 From 01/01/2024 to 03/31/2024 From 01/01/2024 to 03/31/2024 From 10/01/2023 to 12/31/2023 From 10/01/2023 to 12/31/2023 From 07/01/2023 to 09/30/2023 Limit Set 0127-DD 0322-PR 0322-PR 0322-PR 0127-DD 0087-PR 0364-DD 0087-PR 0087-PR 0322-DD Lease Area/Block1 ST, SA-311 GI, SA-115 GI, SA-115 GI, SA-115 ST, SA-311 ST-127 EB-165 ST-127 ST-127 GI, SA-115 Parameter 82597 - Deck drainage, free oil 51954 - Oil & grease, free oil 82599 - Produced water, oil and grease 82599 - Produced water, oil and grease 82597 - Deck drainage, free oil 82599 - Produced water, oil and grease 82597 - Deck drainage, free oil 51954 - Oil & grease, free oil 82599 - Produced water, oil and grease 82597 - Deck drainage, free oil Value Type/ Stat. Base C3 MO TOTAL C3 DAILY MX C2 MO AVG C3 DAILY MX C3 MO TOTAL C3 DAILY MX C3 MO TOTAL C3 DAILY MX C2 MO AVG C3 MO TOTAL Reported Limit Value/Units Value/Units 1 day 0 days 106.7 mg/l 42 mg/L 100.8 mg/l 29 mg/L 281.7 mg/l 42 mg/L 1 day 0 days 58.1 mg/l 42 mg/L 2 days 0 days 69 mg/l 42 mg/L 69 mg/l 42 mg/L 1 day 0 days 1 ST, SA = South Timbalier, South Addition; GI, SA = Grand Isle, South Addition; ST = South Timbalier; EB = East Breaks Review Period: 05/11/2023 - 05/31/2025 Attachment B Environmental Protection Agency Integrated Compliance Information System (ICIS) DMR Non-Receipt Violations GMG290269 Monitoring Period End Date 12/31/2023 12/31/2023 12/31/2023 Monitoring Period From 10/01/2023 to 12/31/2023 From 10/01/2023 to 12/31/2023 From 10/01/2023 to 12/31/2023 Limit Set 0012-PR 0012-PR 0012-PR Lease Area/ Block2 SS, SA-243 SS, SA-243 SS, SA-243 Parameter 51954 - Oil & grease, free oil 82599 - Produced water, oil and grease (Daily Maximum) 82599 - Produced water, oil and grease (Monthly Average) 51712 - Whole Effluent Toxicity [WET] - M. beryllina NODI Code3 **E** **E** **E** DMR Due Date DMR Submission Date 02/29/2024 02/29/2024 02/29/2024 02/29/2024 02/29/2024 02/29/2024 12/31/2023 From 10/01/2023 to 12/31/2023 0364-PM EB-165 51713 - Whole Effluent Toxicity [WET] Americamysis bahia (formerly Mysidopsis bahia) 51726 - Critical Dilution 51726 - Critical Dilution TOP3E - NOEC Lethal Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia) TOP6J - NOEC Lethal Static Renewal 7 Day Chronic Menidia beryllina TPP3E - NOEC Sub-Lethal Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia) **E** 02/29/2024 02/29/2024 2 SS, SA - Ship Shoal, South Addition; EB = East Breaks 3 Information on DMR Non-Receipt status can be found on here: NPDES DMR Non-Receipt Status Search Help. 11/30/2023 11/30/2023 11/30/2023 From 10/01/2023 to 12/31/2023 From 10/01/2023 to 12/31/2023 From 10/01/2023 to 12/31/2023 0012-PR 0012-PR 0012-PR SS, SA-243 SS, SA-243 SS, SA-243 TPP6J - NOEC Sub-Lethal Static Renewal 7 Day Chronic Menidia beryllina TXP3E - LOEC Lethal Survival Static Renewal 7 Day Chronic Americamysis bahia (formerly Mysidopsis bahia) TXP6J - LOEC Lethal Survival Static Renewal 7 Day Chronic Menidia beryllina TYP3E - LOEC Sub-Lethal Reproduction Static Renewal 7 Day Chronic Americamysis bahia (Mysidopsis bahia) TYP6J - LOEC Sub-Lethal Growth Static Renewal 7 Day Chronic Menidia beryllina 51954 - Oil & grease, free oil 82599 - Produced water, oil and grease (Daily Maximum) 82599 - Produced water, oil and grease (Monthly Average) **E** 02/29/2024 02/29/2024 **E** 02/29/2024 02/29/2024 **E** 02/29/2024 02/29/2024 Inspection Date: 09/24/2024 BSEE Inspection ID: 524190481 Records Review Period: 8/1/2022-7/31/2024 Lease Area/Block: Grand Isle 115 ATTACHMENT C BSEE Inspection Report Violations GMG290129 Permitted Feature 0322 PF/Limit Set 0322-DC 0322-DW 0322-PR 0322-PR 0322-PR 0322-PR 0322-PR 0322-PR 0322-PR 0322 Description of Violations The Best Management Practices (BMP) Plan was dated August 2016; the review or revision of the BMP Plan is due in 2025. BSEE and EPA Inspectors observed foam from the domestic waste discharge location during the inspection. Multiple chains of custody (COC) for produced water oil and grease samples were incomplete. Sample custody seals were reused for produced water oil and grease samples. For the March 2024, oil and grease sample for produced water, the date is different for the lab analysis report (3/1) and the DMR (3/5). Facility personnel analyze the temperature of the produced water oil and grease sample by placing the thermometer directly in the lab sample. The August 2024 produced water oil and grease sample was not properly preserved (pH > 2 standard units). During the inspection, BSEE and EPA Inspectors observed a sheen from a produced water discharge location that was not observed by facility personnel. Facility personnel are unfamiliar with produced water oil and grease sampling protocols for sheen events. There was no thermometer in the sample storage area. Violation Date(s) 09/24/2024 09/24/2024 09/24/2024 09/24/2024 March 2024 09/24/2024 August 2024 09/24/2024 09/24/2024 09/24/2024 Permit Citation Part II, Section B, 2, c, 2, Best Management Practices, d Part I, Sec. B, 9, a Part II, Sec. C, 4, a-g Part I, Sec. B, Note 1-2 Part II, Sec. D, 4 Part I, Sec. B, Note 1-2 Part I, Sec. B, Note 1-2 Part I, Sec. B, 4, b, Visual Sheen Part I, Section B, 4, b Part I, Sec. B, Note 1-2