This electronic book on CD-ROM provides an unprecedented collection of authoritative official documents and technical reports about the process of hydraulic fracturing, also known as hydrofrac or fracking, to extract natural gas, along with gas exploration and production in the Marcellus shale field of New York, Pennsylvania, West Virginia, and Ohio. There is comprehensive coverage of all aspects of the issue, including the ongoing controversy about the environmental and safety risks arising from possible water pollution and drinking water contamination. Contents include material from the EPA, USGS, Department of Energy, U.S. Congress, and others. There is a complete reproduction of EPA public meeting comments from events in Texas, Colorado, Pennsylvania, and New York, offering valuable insight into the controversy. Technical documents and regulations provide unique details and understanding. While limited production has occurred in the Marcellus Shale to date, drillers in the Barnett Shale of Texas have demonstrated that new technology in the form of horizontal drilling and hydraulic fracturing of the shale (fracturing through the use of high pressure liquids) has helped overcome the flow capacity problem of gas shales. Horizontal drilling is a technique used to expose long sections of the reservoir rock to the wellbore. While a conventional vertical well penetrates and exposes only the thickness of a pay zone (e.g., 50 to 300 feet in the Marcellus shale), horizontal drilling can expose over a mile of reservoir rock for production by steering a drill bit to follow the pay zone. Hydraulic fracture stimulation creates additional flow paths to the well. In this process, fluid is pumped into the formation at high enough pressures and rates to split the rock. Sized particles such as sand are also mixed with the fracturing fluid to hold the crack open once pumping stops. In addition, wells can be oriented to intersect natural fractures that occur in many formations. As t