Energy futuresShale gas development and healthy water sources
Geological formation known as the Marcellus Shale contains gas reservoir holding nearly 500 trillion cubic feet of technically recoverable gas; at current use rates, that volume could meet the U.S. demand for natural gas for more than twenty years; trouble is, extracting shale gas involves considerable pollution risks for water; Pennsylvania has more miles of stream per unit land area than any other state in the United States – and it is concerned about the quality of its water if more shale gas is extracted
Amity, Pennsylvania is the epicenter of the natural gas-containing geological formation known as the Marcellus Shale. Amity lies in Washington County near Anawanna, Pennsylvania. Once, Native Americans lived there. They named it Anawanna, or “the path of the water,” in recognition of its many rivers and streams.
Today the Native American Anawanna, or the path of the water, is making headlines. A National Science Foundation release reports that the Marcellus Shale Formation underlies some 95,000 square miles of land, from upstate New York in the north to Virginia in the south to Ohio in the west.
The bull’s-eye, however, is under Pennsylvania in places like Amity. There the gas-bearing thickness of the shale reaches 350 feet (it thins to less than fifty feet in other areas).
The Marcellus Shale gas reservoir may contain nearly 500 trillion cubic feet of technically-recoverable gas. At current use rates, that volume could meet the U.S. demand for natural gas for more than twenty years (see Daniel Yergin. “America’s New Energy Security,” Wall Street Journal 12 December 2011).
The shale’s proximity to the heavily populated mid-Atlantic and Northeast makes its development economically advantageous. Already, more than 4,000 shale gas wells have been drilled in Pennsylvania.
The Marcellus Shale has a bête noire, however. With such rapid development, gas exploitation is creating environmental challenges for Pennsylvania — and beyond.
Retrieving the Marcellus Shale’s gas requires a process known as hydraulic fracturing, hydrofracking or simply fracking.
Fracking involves the use of large quantities of water, three to eight million gallons per well, mixed with additives, to break down the rocks and free up the gas. Some 10 to as much as 40 percent of this fluid returns to the surface as “flowback water” as the gas flows into a wellhead.
Once a well is in production and connected to a pipeline, it generates what is known as produced water. “Flowback and produced water,” says Susan Brantley, a geoscientist at Penn State University, “contain fluid that was injected from surface reservoirs — and ‘formation water’ that was in the shale before drilling.”
These flowback fluids carry high concentrations of salts, and of metals, radionuclides and methane. “Such chemicals,” says Brantley, “can affect surface and groundwater quality if released to the environment without adequate treatment.”
The rapid pace of Marcellus Shale drilling has outstripped Pennsylvania’s ability to document pre-drilling water quality, even with some 580 organizations focused on monitoring the state’s watersheds. More than 300 are community-based
