{"operation":"document","citation":"CPF 12025015WL","title":"DTM GAS STORAGE COMPANY — Warning Letter","source_type":"enforcement","agency":"Pipeline and Hazardous Materials Safety Administration","status":"historical","official":true,"published_on":"2025-05-29","effective_on":null,"summary":"CLOSED warning letter citing 192.12(b)(2), 192.12(c).","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-enforcement-12025015wl.json","markdown":"https://regulus.evalyn.ai/document/phmsa-enforcement-12025015wl.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-enforcement-12025015wl","source_url":"https://primis.phmsa.dot.gov/enforcement-data/case/12025015WL","body":"Warning Letter involving DTM GAS STORAGE COMPANY. PHMSA's enforcement data identifies the cited regulations as 192.12(b)(2),  192.12(c). The case was opened on 2025-05-29 and is reported as closed as of 2025-05-29. Open the official case record for notices, responses, orders, and the latest status.\n\nOfficial case documents:\n\n12025015WL_Warning Letter_05292025_(24-296375).pdf: https://primis.phmsa.dot.gov/enforcement-documents/12025015WL/12025015WL_Warning%20Letter_05292025_(24-296375).pdf\n\n12025015WL_Warning Letter_05292025_(24-296375)_text.pdf: https://primis.phmsa.dot.gov/enforcement-documents/12025015WL/12025015WL_Warning%20Letter_05292025_(24-296375)_text.pdf\n\n12025015WL_Warning Letter_05292025_(24-296375)_text.pdf\n\nWARNING LETTER\nVIA ELECTRONIC MAIL TO: david.slater@dtmidstream.com\nMay 29, 2025\nMr. David Slater\nPresident and Chief Executive Officer\nDT Midstream Gas Storage Company\n500 Woodward Avenue\nDetroit, Michigan 48226\nCPF 1-2025-015-WL\nDear Mr. Slater:\nFrom May 29 to May 31 and July 23 to July 25, 2024, a representative of the Pipeline and\nHazardous Materials Safety Administration (PHMSA) pursuant to Chapter 601 of 49 United States\nCode (U.S.C.) inspected DT Midstream Gas Storage Company’s (DTM) Washington 10 Complex\nunderground natural gas storage facility in Macomb, Michigan.\nAs a result of the inspection, it is alleged that you have committed probable violations of the\nPipeline Safety Regulations, Title 49, Code of Federal Regulations (CFR). The items inspected\nand the probable violations are:\n1. § 192.12 Underground natural gas storage facilities.\n(a) …\n(b) Depleted hydrocarbon and aquifer reservoir UNGSFs.\n(1) …\n(2) Each UNGSF that uses a depleted hydrocarbon reservoir or an\naquifer reservoir for natural gas storage and was constructed on or\nbefore July 18, 2017, must meet the provisions of API RP 1171\n(incorporated by reference, see §192.7), sections 8, 9, 10, and 11, and\nparagraph (c) of this section, by January 18, 2018, and must meet all\nprovisions of paragraph (d) of this section by March 13, 2021.\nDTM failed to meet the provisions of American Petroleum Institute Recommended Practice 1171\n(API RP 1171), Section 9. Specifically, DTM’s records did not demonstrate that functional\n\n\n\nintegrity of the reservoir was maintained in an ongoing basis in accordance with API RP 1171,\nSection 9.2.1 (Section 9.2.1).\nSection 9.2.1 states in part, “[t]he operator shall maintain functional integrity of storage wells and\nreservoirs. Storage wells and reservoirs can have different characteristics resulting in unique\nrequirements in approaching integrity demonstration, verification, and monitoring.”\nDuring the inspection, PHMSA reviewed DTM’s Washington 10 reservoir records pertaining to\ngas storage inventory assessment and verification. The Washington 10 Gas Storage Field: Fall\n2021 Inventory Report indicated a quantified possible loss of 2.546 BCF storage gas. The\nWashington 10 Gas Storage Field: Fall 2022 Inventory Report indicated as well quantified\npossible loss of 2.729 BCF storage gas attributed to multiple uncertainties such accounting,\nmeasurement accuracy, and geologic aspects. Due to these issues from reservoir integrity\nassessment and verification records, DTM could not demonstrate functional integrity of\nWashington 10 reservoir. Washington 10 Gas Storage Field Geological Characterization June\n2022 report noted that there was work necessary to reduce reservoir risk including: “[r]eview off-\nreef Regional Brown Niagaran penetrations along the southern Michigan reef trend to study inter-\nreef formation characteristics compared to near-reef formation characteristics” and “[e]valuate\nBass Island formation for another shallower vertical containment formation.”\nTherefore, DTM failed to demonstrate that functional integrity of the reservoir as required API RP\n1171, Section 9.2.1, pursuant to § 192.12(b)(2).\n2. § 192.12 Underground natural gas storage facilities.\n(a) …\n(c) Procedural manuals. Each operator of a UNGSF must prepare\nand follow for each facility one or more manuals of written procedures\nfor conducting operations, maintenance, and emergency preparedness\nand response activities under paragraphs (a) and (b) of this section.\nEach operator must keep records necessary to administer such\nprocedures and review and update these manuals at intervals not\nexceeding 15 months, but at least once each calendar year. Each\noperator must keep the appropriate parts of these manuals accessible\nat locations where UNGSF work is being performed. Each operator\nmust have written procedures in place before commencing operations\nor beginning an activity not yet implemented.\nDTM failed to prepare and follow for each facility one or more manuals of written procedures for\nconducting operations, maintenance, and emergency preparedness. Specifically, DTM failed to\nfollow its 1050 Gas Storage Well Site Security and Safety procedure, revision September 2024,\nSection 4.10.1 (MS-OPS-S011) regarding documenting annual well site safety and security\nreviews.\n\n\n\nDTM’s MS-OPS-S011 stated in part:\nThe Operations Manager shall schedule and the Storage IM Program Owner verify\nthe completion of an annual well site inspection for active injection, withdrawal, and\nobservation wells to occur once each calendar year, not to exceed 15-months, for\nreview of safety and security of the wellhead, well site, access roads, and above-\nground equipment (API 1171 10.5), documented on the applicable inspection form\n(1050-1 for active wells and 1050-2 for plugged wells).\nDuring the inspection, PHMSA reviewed annual well site inspection documentation pertaining to\nsite security of wells at the storage facility. For calendar year 2023, Form 1050-1 Well Inspection\nForm for wells Couch Estate Well 2-22 and Frost Well 1-21 were missing information and\ninadequate in demonstrating site security of these wells had been conducted and reviewed.\nTherefore, DTM failed to follow its MS-OPS-S011 procedure regarding documenting annual well\nsite safety and security reviews for two wells during calendar year 2023.\nUnder 49 U.S.C. § 60122 and 49 CFR § 190.223, you are subject to a civil penalty not to exceed\n$272,926 per violation per day the violation persists, up to a maximum of $2,729,245 for a related\nseries of violations. For violation occurring on or after December 28, 2023 and before December\n30, 2024, the maximum penalty may not exceed $266,015 per violation per day the violation\npersists, up to a maximum of $2,660,135 for a related series of violations. For violation occurring\non or after January 6, 2023 and before December 28, 2023, the maximum penalty may not exceed\n$257,664 per violation per day the violation persists, up to a maximum of $2,576,627 for a related\nseries of violations. For violation occurring on or after March 21, 2022 and before January 6, 2023,\nthe maximum penalty may not exceed $239,142 per violation per day the violation persists, up to\na maximum of $2,391,142 for a related series of violations. For violation occurring on or after\nMay 3, 2021 and before March 21, 2022, the maximum penalty may not exceed $225,134 per\nviolation per day the violation persists, up to a maximum of $2,251,334 for a related series of\nviolations. For violation occurring on or after January 11, 2021 and before May 3, 2021, the\nmaximum penalty may not exceed $222,504 per violation per day the violation persists, up to a\nmaximum of $2,225,034 for a related series of violations. For violation occurring on or after July\n31, 2019 and before January 11, 2021, the maximum penalty may not exceed $218,647 per\nviolation per day the violation persists, up to a maximum of $2,186,465 for a related series of\nviolations.\nWe have reviewed the circumstances and supporting documents involved in this case, and have\ndecided not to conduct additional enforcement action or penalty assessment proceedings at this\ntime. We advise you to correct the items identified in this letter. Failure to do so will result in DTM\nGas Storage Company being subject to additional enforcement action.\nNo reply to this letter is required. If you choose to reply, in your correspondence please refer to\nCPF 1-2025-015-WL. Be advised that all material you submit in response to this enforcement\naction is subject to being made publicly available. If you believe that any portion of your\nresponsive material qualifies for confidential treatment under 5 U.S.C. § 552(b), along with the\ncomplete original document you must provide a second copy of the document with the portions\n\n\n\nyou believe qualify for confidential treatment redacted and an explanation of why you believe the\nredacted information qualifies for confidential treatment under 5 U.S.C. § 552(b).\nSincerely,\nRobert Burrough\nDirector, Eastern Region, Office of Pipeline Safety\nPipeline and Hazardous Materials Safety Administration","truncated":false,"body_characters":8846}