The Pacific Institute has issued a study of issues related to hydraulic fracturing and water resources: Hydraulic Fracturing and Water Resources: Separating the Frack from the Fiction. The Pacific Institute is a non-profit research and policy organization based in Oakland, California. The study is largely a summary of interviews of environmental and industry experts and of research in the area; it provides a good summary of the present issues surrounding fracing and the literature on the subject.
The authors comment on the debate of whether hydraulic fracturing is the cause of any groundwater contamination by characterizing it as an issue of definition: those in the industry, they say, define the term narrowly as including only the actual process by which fluids are injected into the wellbore under pressure to fracture the formation. The authors elect to define the term more broadly, "to include impacts associated with well construction and completion, the hydraulic fracturing process itself, and well production and closure." It is true that people outside the industry have tended to use the term "fracing" to include anything that can go wrong in the process of drilling, completing and producing a well and cause contamination. It is a mistake, however, to use the term to include risks of contamination from well construction, production and closure; those risks occur with all wells, whether they are vertical or horizontal and whether they are completed in shale or conventional formations.
The authors discuss the following issues surrounding "fracing," as they broadly define it:
The study has the following graphic showing the amount of water used in fracing:
The authors point out that use of water for fracing is a "consumptive" use, meaning that the water is not available for subsequent use but is generally disposed of by injection into disposal wells, so that it leaves the water cycle. They cite a report that, in Texas, companies have recently been paying between $9,500 and $17,000 per million gallons ($.40 to $.70 per barrel) for frac water. In addition to affecting the availability of water for other uses, withdrawal of such large quantities of water can adversely affect water quality, according to the study: "withdrawals of large volumes of water can adversely impact groundwater quality through a variety of means, such as mobilizing naturally occurring substances, promoting bacterial growth, causing land subsidence, and mobilizing lower quality water from surrounding areas."
Groundwater Contamination Associated with Well Drilling and Production
This is the problem of defective casing, which has been documented to cause groundwater contamination by methane. Such contamination can also take place through old abandoned wellbores when a well in close proximity is fraced. The authors cite the controversial study in Pennsylvania that found methane levels in drinking water wells located within 1 kilometer from a gas well were 17 times higher than in water wells outside of active gas production areas. And the authors discuss the controversial EPA study of wells in Pavilion, Wyoming and the contamination of groundwater by methane in Dimock, Pennsylvania as associated with poor casing practices.
The authors include contamination caused by poor wastewater management practices as a problem associated with fracing - poorly constructed disposal wells, attempts to use municipal treatment facilities to treat frac water, and the long hauls of flowback water to distant disposal wells.
Another "fracing" problem the authors associate with fracing: they estimate 3,950 truck trips per well for horizontal shale wells, including hauling of fresh water to the wells.
Surface Spills and Leaks
The authors list the following causes of land and groundwater contamination under this heading: accidents and equipment failure during onsite mixing of frac fluids; vandalism; illegal dumping and disposal of flowback water; and truck accidents.
This is the risk of contamination caused by runoff from wellsites.
The authors call for more study of the effects of well operations in these areas, "to clarify terms and definitions associated with hydraulic fracturing, to support more fruitful and informed dialog and to develop appropriate energy, water, and environmental policy."