WESTERN MIDSTREAM PARTNERS, LP — Warning Letter

520205003W_Warning Letter (REVISED)_04092020_text.pdf, page 1Official PDFWARNING LETTER VIA E-MAIL TO MR. CRAIG COLLINS April 9, 2020 Mr. Craig Collins Senior Vice President and Chief Operating Officer Anadarko Petroleum Corporation 5 Greenway Plaza, Suite 110 Houston, TX 77046 CPF 5-2020-5003W Dear Mr. Collins: On July 18, 2019, a representative of the Pipeline and Hazardous Materials Safety Administration (PHMSA), pursuant to Chapter 601 of 49 United States Code (U.S.C.), conducted an accident investigation of an incident involving your pipeline facilities near Red Desert, Wyoming that was discovered on July 15, 2019. As a result of the investigation, it is alleged that you have committed a probable violation of the Pipeline Safety Regulations, Title 49, Code of Federal Regulations (CFR). The item inspected and the probable violation is: 1. § 195.302 General requirements. (a) Except as otherwise provided in this section and in §195.305(b), no operator may operate a pipeline unless it has been pressure tested under this subpart without leakage. In addition, no operator may return to service a segment of pipeline that has been replaced, relocated, or otherwise changed until it has been pressure tested under this subpart without leakage.#

520205003W_Warning Letter (REVISED)_04092020_text.pdf, page 2Anadarko Petroleum Corporation transported product through an abandoned pipeline, Wamsutter Trunk “C” mainline, prior to pressure testing it without leakage under Part 195, Subpart E. Specifically, on May 14, 2003, the Wamcutter Trunk “C” Mainline was abandoned (see Exhibit A). In December 2018, operator personnel were performing maintenance on Wamsutter Trunk “B” Mainline, when an inline inspection tool became stuck inside. The operator decided to reroute the product stuck in Trunk B through the abandoned Trunk “C” Mainline. Based on conversations with the operator’s personnel, Trunk “C” Mainline was not hydrotested prior to the product being rerouted. 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 identified in this letter. Failure to do so will result in Anadarko Petroleum Corporation 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 5- 2020-5003W. 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, Dustin Hubbard Director, Western Region Pipeline and Hazardous Materials Safety Administration cc: PHP-60 Compliance Registry PHP-500 S. Perkins (#166350)#

520205003W_Warning Letter_02282020_text.pdf, page 1Official PDFWARNING LETTER CERTIFIED MAIL - RETURN RECEIPT REQUESTED February 28, 2020 Mr. Al Walker President Anadarko Petroleum Corporation 5 Greenway Plaza, Suite 110 Houston, TX 77046 CPF 5-2020-5003W Dear Mr. Walker: On July 18, 2019, a representative of the Pipeline and Hazardous Materials Safety Administration (PHMSA), pursuant to Chapter 601 of 49 United States Code (U.S.C.), conducted an accident investigation of an incident involving your pipeline facilities near Red Desert, Wyoming that was discovered on July 15, 2019. As a result of the investigation, it is alleged that you have committed a probable violation of the Pipeline Safety Regulations, Title 49, Code of Federal Regulations (CFR). The item inspected and the probable violation is: 1. § 195.302 General requirements. (a) Except as otherwise provided in this section and in §195.305(b), no operator may operate a pipeline unless it has been pressure tested under this subpart without leakage. In addition, no operator may return to service a segment of pipeline that has been replaced, relocated, or otherwise changed until it has been pressure tested under this subpart without leakage. Anadarko Petroleum Corporation transported product through an abandoned pipeline, Wamsutter Trunk “C” mainline, prior to pressure testing it without leakage under Part 195, Subpart E. Specifically, on May 14, 2003, the Wamcutter Trunk “C” Mainline was abandoned (see Exhibit A). In December 2018, operator personnel were performing maintenance on Wamsutter Trunk#

520205003W_Warning Letter_02282020_text.pdf, page 2“B” Mainline, when an inline inspection tool became stuck inside. The operator decided to reroute the product stuck in Trunk B through the abandoned Trunk “C” Mainline. Based on conversations with the operator’s personnel, Trunk “C” Mainline was not hydrotested prior to the product being rerouted. 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 identified in this letter. Failure to do so will result in Anadarko Petroleum Corporation 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 5-2020-5003W. 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, Dustin Hubbard Director, Western Region Pipeline and Hazardous Materials Safety Administration cc: PHP-60 Compliance Registry PHP-500 S. Perkins (#166350) 2#