DTM GAS STORAGE COMPANY — Warning Letter

32024024WL_Warning Letter_03152024_(23-265890)_text.pdf, page 1Official PDFWARNING LETTER VIA ELECTRONIC MAIL TO: chris.zona@dtmidstream.com, patrick.raichel@dtmidstream.com March 15, 2024 Mr. Christopher Zona Chief Operating Officer DTM Gas Storage Company 500 Woodward Ave., 29th Floor Detroit, MI 48226 CPF 3-2024-024-WL Dear Mr. Zona: On August 1-3, 11, and 16, 2023, representatives of the Michigan Public Service Commission, acting as an interstate agent for the Pipeline and Hazardous Materials Safety Administration (PHMSA), pursuant to Chapter 601 of 49 United States Code (U.S.C.), inspected DTM Gas Storage Company’s (DTM) records and conducted an on-site facilities review in Washington Township, Michigan. As a result of the inspection, it is alleged that DTE has committed probable violations of the Pipeline Safety Regulations, Title 49, Code of Federal Regulations (CFR). The items inspected and the probable violations are: 1. § 192.603 General provisions. (a) . . . . (b) Each operator shall keep records necessary to administer the procedures established under § 192.605. DTM did not have records to demonstrate that training occurred for the appropriate operating personnel to assure that they are knowledgeable of the emergency procedures and to verify that the training was effective. In the Emergency Plan, section 3.13#

32024024WL_Warning Letter_03152024_(23-265890)_text.pdf, page 2“Training” subsection B(i) discussed initial training, and B(ii) discussed annual refresher training, which stated, "This training will be conducted at least once each calendar year." Section 192.603 required that DTM keep records necessary to administer the procedures established under § 192.615. Section 192.615(b) required DTM to train the appropriate operating personnel to assure that they are knowledgeable. During the inspection, DTM personnel indicated that safety training was done during onboarding, but DTM did not have records to demonstrate that this was done in calendar year 2022. 2. § 192.907 What must an operator do to implement this subpart? (a) General. No later than December 17, 2004, an operator of a covered pipeline segment must develop and follow a written integrity management program that contains all the elements described in § 192.911 and that addresses the risks on each covered transmission pipeline segment. The initial integrity management program must consist, at a minimum, of a framework that describes the process for implementing each program element, how relevant decisions will be made and by whom, a time line for completing the work to implement the program element, and how information gained from experience will be continuously incorporated into the program. The framework will evolve into a more detailed and comprehensive program. An operator must make continual improvements to the program. DTM did not follow its Integrity Management procedures, specifically Procedure 902, entitled “High and Moderate Consequence Area Identification,” section 5.6.2, which required that HCA field verification digs be documented on Field Verification Form 902- 001. During the inspection, the records reviewed for two field verifications were found to be documented on incorrect forms. Additionally, the documentation reviewed did not contain all the required elements of Form 902-001, as required by the procedures. Proposed Civil Penalty Under 49 U.S.C. § 60122 and 49 CFR § 190.223, you are subject to a civil penalty not to exceed $266,015 per violation per day the violation persists, up to a maximum of $2,660,135 for a related series of violations. For violation occurring on or after January 6, 2023 and before December 28, 2023, the maximum penalty may not exceed $257,664 per violation per day the violation persists, up to a maximum of $2,576,627 for a related series of violations. For violation occurring on or after March 21, 2022 and before January 6, 2023, the maximum penalty may not exceed $239,142 per violation per day the violation persists, up to a maximum of $2,391,142 for a related series of violations. For violation occurring on or after May 3, 2021 and before March 21, 2022, the maximum penalty may not exceed $225,134 per violation per day the violation persists, up to a maximum of $2,251,334 for a related series of violations. For violation occurring on or after January 11, 2021 and before May 3, 2021, the maximum penalty may not exceed $222,504 per violation per day the violation persists, up to a maximum of $2,225,034 for a related series of violations. For violation occurring on or after July 31, 2019 and before January 11, 2021, the maximum penalty may not exceed $218,647 per violation per day the violation persists, up to a maximum of $2,186,465 for a related series of violations. For violation#

32024024WL_Warning Letter_03152024_(23-265890)_text.pdf, page 3occurring on or after November 27, 2018 and before July 31, 2019, the maximum penalty may not exceed $213,268 per violation per day, with a maximum penalty not to exceed $2,132,679. We have reviewed the circumstances and supporting documents involved in this case, and have decided not to conduct additional enforcement action or penalty assessment proceedings at this time. We advise you to correct the items identified in this letter. Failure to do so will result in DTM Gas Storage Company being subject to additional enforcement action. No reply to this letter is required. If you choose to reply, in your correspondence please refer to 3-2024-024-WL. Be advised that all material you submit in response to this enforcement action is subject to being made publicly available. If you believe that any portion of your responsive material qualifies for confidential treatment under 5 U.S.C. § 552(b), along with the complete original document you must provide a second copy of the document with the portions you believe qualify for confidential treatment redacted and an explanation of why you believe the redacted information qualifies for confidential treatment under 5 U.S.C. § 552(b). Sincerely, Gregory A. Ochs Director, Central Region, Office of Pipeline Safety Pipeline and Hazardous Materials Safety Administration cc: Patrick Raichel (patrick.raichel@dtmidstream.com)#