Officers

Ms. Mannen is president and chief executive officer of MPLX GP LLC. She is also president and chief executive officer of Marathon Petroleum Corporation.

Ms. Mannen was named president of Marathon Petroleum Corporation in January 2024 and assumed her current role in August 2024. Previously, she served as executive vice president and chief financial officer of Marathon Petroleum Corporation since 2021.

Prior to joining Marathon Petroleum Corporation in 2021, Ms. Mannen served as executive vice president and chief financial officer of TechnipFMC, a leading global engineering services and energy technology company incorporated in the United Kingdom and headquartered in Paris and Houston. From 2011 to 2017, she was chief financial officer at FMC Technologies, prior to its merger with Technip SA, which Ms. Mannen played a key role in negotiating and executing. Before that, she served as the company's deputy chief financial officer and treasurer from 2010 to 2011 and vice president of administration from 2007 to 2010. Prior to joining FMC Technologies in 1986, Ms. Mannen was finance manager for Sheller-Globe Corporation.

Ms. Mannen holds a bachelor's degree in accounting and a Master of Business Administration degree from Rider University.

Ms. Mannen serves on the boards of directors of MPLX GP LLC and Marathon Petroleum Corporation. She is a member of the Owens Corning board of directors, where she has served as the audit committee chair since 2019. Ms. Mannen also serves on the executive committee of the American Petroleum Institute (API), the executive committee of American Fuel and Petrochemical Manufacturers (AFPM), and the executive committee of the Ohio Business Roundtable, and is a member of The Business Council. She also serves as secretary of the Cynthia Woods Mitchell Pavilion board of directors and is a member of its executive and finance committees.

Mr. Hagedorn is executive vice president and chief financial officer – MPLX.

Mr. Hagedorn joined MPLX GP LLC in 2017 as vice president and controller. In 2021, he was named senior vice president and controller of Marathon Petroleum Corporation. Prior to joining MPLX GP LLC, Mr. Hagedorn was vice president and controller at CONSOL Energy Inc. He was a key member of the leadership team that prepared for the formation and initial public offering of a midstream master limited partnership formed by CONSOL Energy and served as the partnership's chief accounting officer. Mr. Hagedorn joined CONSOL in 2012 as director, financial accounting and was named assistant controller in 2014, and vice president and controller in 2015. He served as chief accounting officer for CONE Midstream Partners LP from 2014 to 2015. Mr. Hagedorn joined PricewaterhouseCoopers in 1998. During his 14-year career with PwC, he held the positions of audit associate, audit senior associate, audit manager and audit senior manager. Mr. Hagedorn assumed his current position in 2024.

Mr. Hagedorn earned a bachelor’s degree in accounting from West Virginia University. He is a licensed certified public accountant in Pennsylvania.

Mr. Hagedorn serves on the board of directors of MPLX GP LLC.

Mr. Floerke is executive vice president and chief operating officer – MPLX.  

Mr. Floerke joined MPLX in 2015, at the time of the MPLX and MarkWest combination. He joined MarkWest in 2013 as senior vice president, Northeast region. He was named executive vice president and chief commercial officer in 2015 and named executive vice president, gathering and processing in 2016. In 2020, Mr. Floerke was named chief operating officer and executive vice president, Gathering & Processing, Trucks & Rail and assumed his current position in 2021. Prior to joining MarkWest, Mr. Floerke served as vice president, Eastern region for Access Midstream Partners. He has a broad background spanning multiple disciplines and industries for more than 25 years, including senior management roles at Williams, where he began his career, as well as MasTec, Alberici, One Communications, and Chesapeake Midstream.

Mr. Floerke graduated from the Colorado School of Mines with a bachelor’s degree in petroleum engineering. He is a graduate of the Program for Management Development at Harvard Business School.

Mr. Floerke serves on the board of directors of TransTech Group, LLC.

Mr. Lyon is senior vice president Logistics & Storage – MPLX.

Mr. Lyon joined Marathon Petroleum Company in 1989 as an engineer in Indianapolis, Indiana. While in Indianapolis, he worked in various positions in the midstream and engineering organizations. In 2002, Mr. Lyon transferred to Findlay, Ohio, where he has held a variety of leadership positions. He was named product quality manager in 2005 and operations manager for Marathon Pipe Line LLC (MPL), a wholly owned subsidiary of MPLX, in 2006. Mr. Lyon was named district manager in Transport and Rail for the Terminal, Transport and Marine business in 2008 and manager, Marketing and Transportation Engineering for Marathon Petroleum Company in 2010. He was named vice president of operations for MPL in 2011. In 2018, Mr. Lyon was named vice president, operations of MPLX GP LLC and president of MPL. He assumed his current position in 2022.

Mr. Lyon graduated from Purdue University with a Bachelor of Science degree in construction engineering in 1989. He was licensed as a Professional Engineer in 1994.   

Mr. Lyon, by appointment of the U.S. Secretary of Transportation, Elaine Chao, has served on the liquid pipeline advisory committee since 2019. He served as the chair on the board of the Liquid Energy Pipeline Association (LEPA) in 2023; and serves as chair of the board of the Louisiana Offshore Oil Port (LOOP). In 2019, Mr. Lyon received the Pipeline Leadership Award for driving transformation and improvement in the industry. Mr. Lyon served as past member and 2021 chair of the American Petroleum Institute’s (API) pipeline subcommittee steering group; the API-LEPA pipeline safety excellence steering committee; and the LEPA Federal Energy Regulatory Commission (FERC) policy committee. He co-chaired the public engagement recommended practice development group which includes industry, public and government entities for the entire pipeline segment. Mr. Lyon also served as chair of the pipeline industry’s implementation of the Pipeline Safety Management System (API RP 1173) from 2015-2018 and on the Michigan Pipeline Safety Advisory Board, by appointment of Governor Rick Snyder, from 2017-2018.

Mr. Lyon has actively worked to foster a culture of safety within MPL and across the industry. In 2019 and 2023, MPL was awarded the API Distinguished Pipeline Safety Award. Selected by pipeline industry peers, the award acknowledged MPL for fostering a culture of safety, sharing and implementing best practices, and actively participating in and contributing to API policy and technical work.

Mr. Aydt is executive vice president, Refining of Marathon Petroleum Corporation. He is also executive vice president of MPLX GP LLC.

Mr. Aydt joined Marathon in 1985 as a pipeline engineer. He held a series of positions of increasing responsibility in Marketing and Transportation Engineering’s pipeline and retail divisions. In 1991, he helped develop a crude pipeline and trucking project in Tunisia, North Africa. He returned to pipeline operations in Wyoming in 1992, before being named pipeline engineering manager in 1995. In 1999, Mr. Aydt was named project director for the development and construction of the Cardinal Pipeline, which runs from Kenova, West Virginia, to Columbus, Ohio. He was named engineering department manager at the Robinson refinery in 2003, and manager of refining major projects in 2005. Mr. Aydt served as project director for the $2.2 billion Detroit Heavy Oil Upgrade Project from 2008, until its completion in 2012 and was named general manager of Terminal, Transport and Rail in 2013. In 2017, he was appointed president, Marathon Pipe Line LLC and vice president, operations of MPLX GP LLC. In 2018, Mr. Aydt was named vice president, business development of MPLX GP LLC. In 2020, he was named chief commercial officer and executive vice president, Pipelines, Terminals and Marine and assumed his current position in 2022.

Mr. Aydt graduated from the University of Missouri-Rolla with a bachelor’s degree in mechanical engineering in 1985. He attended Wharton’s Advanced Management Program at the University of Pennsylvania in 2014.

Mr. Aydt is a board member of the American Petroleum Institute (API) Downstream Committee and a board member of the American Fuel and Petrochemical Manufacturers Association (AFPM). Mr. Aydt previously chaired the board of the Louisiana Offshore Oil Port (LOOP) and served as past owner representative of Capline, both of which are significant entities in the nation’s crude oil infrastructure. Mr. Aydt served as past board member of the Association of Oil Pipe Lines (AOPL), past member of the American Petroleum Institute’s (API) pipeline subcommittee steering group; served on the API-AOPL Pipeline Safety Excellence Steering Committee; and served on the U.S. Department of Transportation’s Technical Hazardous Liquid Pipeline Safety Standards Committee.

Ms. Benson is chief legal officer and corporate secretary of MPLX GP LLC. She is also chief legal officer and corporate secretary of Marathon Petroleum Corporation.

Ms. Benson began her career with Marathon as a tax attorney in 1998. She was named Government Affairs manager in 2001 and joined the Law organization as an operations attorney in 2003. Ms. Benson was promoted to senior attorney, downstream business in 2006 and to group counsel, North American production for Marathon Oil Company in Houston in 2010. Ms. Benson was named Marathon Petroleum Corporation group counsel, Law ‐ Corporate and Finance in 2011 and assistant general counsel, Law ‐ Corporate and Finance in 2012. In 2016, she was appointed as vice president, chief securities, governance & compliance officer and corporate secretary. She assumed her current position in 2024.

Ms. Benson graduated from The Ohio State University in 1987 with a bachelor’s degree in political science and a Juris Doctor degree from the University of Toledo College of Law in 1997. She completed the Executive Development Program at Northwestern University’s Kellogg School of Management in 2014.

Ms. Benson currently serves on the board of counselors for the University of Findlay and the board of directors for the Hancock Properties Foundation.

Mr. Heppner is senior vice president of MPLX GP LLC. He is also chief strategy officer and senior vice president Business Development of Marathon Petroleum Corporation.

Mr. Heppner joined Marathon in 1988, where he held a variety of positions of increasing responsibility, including design engineer, construction engineer and project manager. In 1995, Mr. Heppner transferred to Emro Marketing Company, the predecessor of Speedway LLC, where he held various positions including purchasing and commercial services manager; business development manager; director of engineering services; and vice president of operations. In 2010, he was appointed director, wholesale marketing at MPC. In 2014, Mr. Heppner was appointed vice president of transition at Speedway. He was later named senior vice president of engineering services and corporate support at Speedway. He was named vice president, Commercial and Business Development for MPC in 2018 and senior vice president, Strategy and Business Development in 2021. He was named senior vice president of MPLX in 2022 and assumed his current position for MPC in 2024.

Mr. Heppner graduated from Ohio Northern University in 1988 with a Bachelor of Science degree in electrical engineering. He is a registered professional engineer in the state of Illinois. Mr. Heppner attended the Wharton School Advanced Management Program in 2013.

Mr. Heppner serves on the Board of Trustees at Ohio Northern University, as well as the board for Habitat for Humanity. He recently served as president of the United Way of Clark, Champaign and Madison Counties board of trustees, vice president of membership for the Boy Scouts of America, Black Swamp Council and was the campaign chairman for the Clark County March of Dimes. Mr. Heppner is a past member of the Children’s Miracle Network’s Board of Governors and Dayton Children’s Hospital Foundation board of trustees, as well as a past member of Wright State University College of Engineering and Computer Science External Advisory Board.

Mr. Hessling is senior vice president of MPLX GP LLC. He is also chief commercial officer of Marathon Petroleum Corporation.

Mr. Hessling began his career with Marathon in 1990 and served in a variety of Marketing positions in the Midwest. In 1994, he was named acquisition specialist and jobber marketing representative in Michigan, which led to him being named a sales manager. Mr. Hessling relocated to MPC’s Findlay, Ohio, office in 2000 where he was named Midwest exchange negotiator and domestic spot crude oil trader in 2001. In 2002, he was named Marketing coordinating manager and distillate pricing manager in 2004. In 2005, Mr. Hessling was named brand southern district manager in Atlanta. He returned to Findlay in 2011 as crude oil and logistics analysis manager. Mr. Hessling was appointed manager, crude oil and natural gas supply and trading manager in 2014.  He was named senior vice president, Crude Oil Supply and Logistics in 2018 and senior vice president, Global Feedstocks in 2021. He assumed his current position in 2024.

Mr. Hessling graduated with a bachelor’s degree in production management and marketing from Central Michigan University. He attended the Oxford Institute for Energy Studies in 2012.

Mr. Partee is senior vice president of MPLX GP LLC. He is also chief global optimization officer of Marathon Petroleum Corporation.  

Mr. Partee joined Marathon in 1995 as an accountant in Marathon Pipe Line. He progressed through positions of increasing responsibility before being named territory manager in the Wholesale Marketing southern region in 2004, district sales manager in 2006 and coordinating manager in 2008. In 2009, Mr. Partee was named commercial director for Speedway. In 2012, he was named vice president, Business Development and Franchise at Speedway. He served as MPC's manager of crude oil logistics and analysis beginning in 2014 and was named director of Business Development in 2017. He was named vice president, Business Development in February 2018 and senior vice president, Marketing in October 2018. In 2021, he was named senior vice president, Global Clean Products and assumed his current position in 2024.

Mr. Partee holds a bachelor’s degree in accounting from Bowling Green State University and an MBA from the University of Findlay. He is a past attendee of the Oxford Institute for Energy Studies.

Mr. Partee is a member of the American Petroleum Institute, where he previously served on the marketing subcommittee. Mr. Partee serves on the board of trustees at the University of Findlay.

Ms. Iten is vice president and controller of MPLX GP LLC.

Prior to being named vice president and controller of MPLX GP LLC in 2025, Ms. Iten served as assistant controller of Marathon Petroleum Company from 2022. She previously served as director of Accounting for MPLX from 2019. Ms. Iten began her career at Marathon Petroleum in 2013 as an advanced accounting analyst and then as a financial reporting and analyst supervisor. Prior to joining Marathon Petroleum, she held various finance and accounting roles at Sun Communities, Inc., HireRight, Inc., Palace Entertainment Holdings, Inc., and CSN, LLC.

Ms. Iten received a Bachelor of Arts in Accounting from Franklin College in Franklin, Indiana, and a Master of Business Administration from Tiffin University in Tiffin, Ohio. She is a licensed certified public accountant in Indiana.

Ms. Iten serves on the boards of directors as a board member and secretary of Open Arms Domestic Violence & Rape Crisis Services and treasurer for Pacesetter Soccer Club South. She also serves as a committee member and treasurer for Boy Scouts of America, Troop 304.

Ms. Kazarian is vice president Finance and Investor Relations of MPLX GP LLC. She is also vice president Finance and Investor Relations of Marathon Petroleum Corporation.

Prior to joining Marathon Petroleum in 2018 as Vice President, Investor Relations, Ms. Kazarian was a managing director and head of the MLP, Midstream, and Refining Equity Research teams at Credit Suisse. She also worked at Deutsche Bank where she started as a director and was eventually promoted to managing director of MLP, Midstream, and Natural Gas Equity Research. Her career began at Fidelity Management & Research Company where she served as an analyst specializing on various energy industry subsectors. She was named to her current position in January 2023.

Ms. Kazarian graduated from Wellesley College with a Bachelor of Arts degree in economics and political science. She also earned a Master of Business Administration in finance and strategic management from the Wharton Business School at the University of Pennsylvania.