MarkWest Energy Partners, L.P. (NYSE: MWE) (“MarkWest” or “the Partnership”) announced today an operational update regarding the continued development of midstream infrastructure projects in the liquids-rich areas of the Marcellus and Utica Shales. In the Marcellus Shale, the Partnership has safely resumed operations of Plant III at the Houston processing and fractionation complex (“Houston complex”) in Washington County, PA. The Houston complex consists of three processing plants totaling 355 million cubic feet per day (MMcf/d) and 98,000 barrels per day (Bbl/d) of ethane and heavier fractionation capacity. Plant III is a 200 MMcf/d cryogenic facility that has been offline since May 28 th, 2014 after the facility’s heat exchanger was damaged. During the period required to complete all necessary repairs to Houston’s Plant III, MarkWest was able to minimize disruption to its producer customers by utilizing its large, high-pressure, rich-gas header system to route gas to the Majorsville complex in Marshall County, West Virginia for processing. In the Utica Shale, MarkWest Utica EMG, L.L.C. (“MarkWest Utica EMG”), a joint venture between MarkWest and The Energy and Minerals Group (“EMG”), is in startup mode for its third cryogenic processing plant at the Seneca complex in Noble County, Ohio. The 200 MMcf/d Seneca III plant will increase total processing capacity at the complex to 600 MMcf/d. The Seneca complex is supported by long-term, fee-based contracts with Antero Resources Corporation (NYSE: AR), Gulfport Energy Corporation (NASDAQ: GPOR), Rex Energy Corporation (NASDAQ: REXX), PDC Energy Inc. (NASDAQ: PDCE), and other producers. MarkWest Utica EMG continues to expand capacity at the Seneca complex and will complete a fourth 200 MMcf/d plant in the second quarter of 2015. In addition to the Seneca complex, MarkWest Utica EMG’s Cadiz complex in Harrison County, Ohio, also continues to grow rapidly. MarkWest Utica EMG recently completed a 40,000 barrel per day de-ethanization facility at the Cadiz complex. This new facility will provide MarkWest Utica EMG’s producer customers’ with the ability to meet residue gas quality specifications and downstream ethane pipeline commitments. Ethane produced at the new Cadiz facility will be delivered to the ATEX pipeline. In addition, during the third quarter of 2014, the Cadiz II plant will become operational and increase total cryogenic processing capacity at the Cadiz complex to 325 MMcf/d.