MARKWEST PIPELINE COMPANY, L.L.C. — Warning Letter

42021006WL_Warning Letter_02032021_(20-171919)_text.pdf, page 1Official PDFWARNING LETTER ELECTRONIC MAIL - RETURN RECEIPT REQUESTED February 3, 2021 Harold E. Rinehart Vice President G&P Health, Environment Safety & Security Markwest Pipeline Company, LLC 1515 Arapahoe Street Tower 1, Suite 1600 Denver, Colorado 80202 CPF 4-2021-006-WL Dear Mr. Rinehart: From June 8, 2020 through October 27, 2020, a representative of the Pipeline and Hazardous Materials Safety Administration (PHMSA) pursuant to Chapter 601 of 49 United States Code (U.S.C.) inspected Markwest Pipeline Company LLC’s (MarkWest) hazardous liquid transmission pipeline near Carthage, Texas. On the basis of the inspection, it is alleged that MarkWest has committed a probable violation of the Pipeline Safety Regulations, Title 49, Code of Federal Regulations (CFR). The item inspected and the probable violation is:#

42021006WL_Warning Letter_02032021_(20-171919)_text.pdf, page 22 1. § 195.577 What must I do to alleviate interference currents? (a) For pipelines exposed to stray currents, you must have a program to identify, test for, and minimize the detrimental effects of such currents. MarkWest failed to identify and test for alternating current (AC) interference as required by § 195.577(a) at two locations on its 6” Enterprise Y Grade line where a high voltage electrical transmission line crosses the right-of-way. MarkWest’s written procedure SWBU-01 Section 2-Corrosion Control Rev. No. 6 Rev. Date 10/16/2020, subsection 8.25 states: “When a pipeline shares the right of way with a high voltage electrical transmission line, either parallel or perpendicular, AC potentials should be taken at test stations during the normal monitoring cycle.” MarkWest failed to test for AC interference on its pipeline as required by § 195.577(a) and its written procedure for calendar years 2018 and 2019. AC interference checks were observed in the field for the year 2020. Under 49 U.S.C. § 60122 and 49 CFR § 190.223, you are subject to a civil penalty not to 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 occurring 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. For violation occurring on or after November 2, 2015 and before November 27, 2018, the maximum penalty may not exceed $209,002 per violation per day, with a maximum penalty not to exceed $2,090,022. For violations occurring prior to November 2, 2015, the maximum penalty may not exceed $200,000 per violation per day, with a maximum penalty not to exceed $2,000,000 for a related series of violations. 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 item(s) identified in this letter. Failure to do so will result in Markwest Pipeline Company, L.L.C. being subject to additional enforcement action. No reply to this letter is required. If you choose to reply, in your correspondence please refer to CPF 4-2021-006-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).#

42021006WL_Warning Letter_02032021_(20-171919)_text.pdf, page 33 Sincerely, Mary L. McDaniel, P.E. Director, Southwest Region Pipeline and Hazardous Materials Safety Administration cc: Anthony Minutillo, Pipeline Compliance Supervisor, MarkWest Energy Partners, LP, tminutillo@marathonpetroleum.com#