Mr. Semple is the retired chairman, president and chief executive

officer of MarkWest Energy Partners, L.P.

Mr. Semple joined MPLX in 2015, at the time of the MPLX and MarkWest combination and retired in 2016. He joined MarkWest in 2003, as president and chief executive officer and was elected chairman of the board in 2008. Prior to joining MarkWest, Mr. Semple completed a 22‐year career with The Williams Companies and WilTel Communications. He served as the chief operating officer of WilTel Communications, senior vice president/general manager of Williams Natural Gas Company, vice president, operations and engineering for Northwest Pipeline Company and division manager for Williams Pipeline Company. Prior to his time at The Williams Companies, Mr. Semple served in the U.S. Navy. Mr. Simple served as a nuclear submarine officer as a nuclear engineer, and
his last sea duty was on board the USS GURNART (SSN 662).

Mr. Semple earned a bachelor’s degree in mechanical engineering from the United States Naval

Academy. He completed the Program for Management Development at Harvard Business School.

Mr. Semple serves on the boards of directors of MPLX GP LLC, Choctaw Global, LLC, an affiliate of the Choctaw Nation of Oklahoma, National Cowboy & Western Heritage Museum and the Semple Family Museum of Native American Art.