MarkWest Energy Partners LP a Delaware corporation was formed in Delaware on January 24, 2002. The Company is engaged in the gathering, processing and transportation of natural gas; the gathering, transportation, fractionation, storage and marketing of NGLs; and the gathering and transportation of crude oil. The Company has presence in many unconventional gas plays including the Marcellus Shale, Utica Shale, Huron/Berea Shale, Haynesville Shale, Woodford Shale and Granite Wash formation. The Company conducts operations in the following operating segments: Marcellus, Utica, Northeast and Southwest. Its primary business is to provide top-tier midstream services by developing and operating high-quality, strategically located assets in the liquids-rich areas of six core natural gas producing resource plays in the United States. The Company provides services in the midstream sector of the natural gas industry. The midstream natural gas industry is the link between the exploration for and production of natural gas and the delivery of its hydrocarbon components to end-use markets. In the Marcellus segment, it provides fully integrated natural gas midstream services in southwestern Pennsylvania and northern West Virginia through its wholly owned subsidiary, MarkWest Liberty Midstream. The Company operates five processing complexes in its Marcellus segment that include the Houston Complex located in Washington County, Pennsylvania: the Majorsville Complex located in Marshall County, West Virginia; the Mobley Complex located in Wetzel County, West Virginia; the Sherwood Complex located in Doddridge County, West Virginia; and the Keystone Complex located in Butler County, Pennsylvania. In addition, it operates two gathering systems: one currently delivering over 475 MMcf/d of natural gas to its Houston and Majorsville Complexes and the other delivering over 74 MMcf/d of natural gas to its Keystone complex. MarkWest Utica EMG provides gathering, processing, fractionation and marketing services in the liquids-rich corridor of the Utica Shale in eastern Ohio. In each of its operating segments, the company faces competition for natural gas gathering, crude oil transportation and in obtaining natural gas supplies for its processing and related services; in obtaining unprocessed NGLs for gathering and fractionation; and in marketing its products and services. The Company's processing and fractionation plants, pipelines and associated facilities are subject to multiple obligations and potential liabilities under a variety of stringent and comprehensive federal, regional, state and local laws and regulations governing discharges of materials into the environment or otherwise relating to environmental protection.