MPLX LP, Marathon Petroleum Corp.'s (MPC) midstream master limited partnership, announced that Craig Pierson, vice president (VP) of operations at MPLX GP LLC, MPLX's general partner, and president of MPLX's subsidiary, Marathon Pipe Line LLC(MPL), will retire effective Jan. 1. Pierson joined Marathon in 1978 as a pipeline engineer and held numerous positions in pipeline, transportation and logistics and marketing. Pierson was named VP of operations for MPL in 2005 and assumed the role of president in 2011. "Craig has made significant and lasting contributions to the pipeline organization, leading its growth into the flexible and integrated system we operate today," said MPLX President Don Templin. Pierson will be replaced by Timothy Aydt, who is currently a general manager at MPC.