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GAO-14-857R 1 (2014-09-23)

handle is hein.gao/gaobaaihr0001 and id is 1 raw text is: G A U.S. GOVERNMENT ACCOUNTABILITY OFFICE 441 G St. N.W. Washington, DC 20548 September 23, 2014 Congressional Requesters Drinking Water: Characterization of Injected Fluids Associated with Oil and Gas Production Every day in the United States, at least 2 billion gallons of fluids are injected into underground formations to enhance oil and gas production, or to dispose of fluids brought to the surface during the extraction of oil and gas resources.1 Wells used for injecting fluids associated with the extraction of oil and gas resources are known as class II injection wells.2 The majority of fluids injected into class II wells consist largely of brine and may contain pollutants such as chlorides, hydrocarbons, and naturally occurring radioactive materials. The fluids are injected deep underground into porous rock formations, such as sandstone, that are generally below aquifers that can, or do, supply drinking water. Because a significant percentage of the population gets its drinking water from underground aquifers, these wells have raised concerns about the safety of the nation's drinking water. Domestic production of oil and gas has increased dramatically in the last several years, with corresponding increases in wastewater resulting from production processes.3 Specifically, hydraulic fracturing combined with horizontal drilling has increased domestic production from unconventional sources such as shales, tight sandstones, and coalbed formations. Hydraulic fracturing involves the injection of fluids underground, and fluids that are produced from formations during oil and gas production, including fluids from hydraulic fracturing activities that flow back out of the well, must be disposed of or reused. Oil and gas operations that inject fluids underground for disposal or enhanced recovery are regulated by the Environmental Protection Agency (EPA) under the class II Underground Injection Control (UIC) program. However, the Energy Policy Act of 2005 exempted the process of injecting fluids into a well to hydraulically 1 Environmental Protection Agency (EPA), Class II Wells - Oil and Gas Related Injection Wells, accessed September 08, 2014, http:/Iwater.epa.gov/type/groundwater/uic/class2/index.cfm. 2EPA regulates six classes of underground injection wells. Class II wells are used to inject brines and other fluids associated with oil and gas production, as well as hydrocarbons for storage, and are the focus of this report. Additionally, class I wells are used to inject hazardous wastes, industrial non-hazardous liquids, or municipal wastewater beneath the lowermost underground drinking water sources; class III wells are used to inject fluids associated with solution mining of minerals beneath the lowermost underground drinking water source; class IV wells are used to inject hazardous or radioactive wastes into or above underground drinking water sources (these wells are banned unless authorized under a federal or state groundwater remediation project); class V wells, in general, are used to inject nonhazardous fluids into or above underground drinking water sources, and are typically shallow, on- site disposal systems; class VI wells are used to inject carbon dioxide for long-term storage. 3GAO, Oil and Gas: Information on Shale Resources, Development, and Environmental and Public Health Risks, GAO 12-732 (Washington, D.C.: Sept. 5, 2012). GAO-14-857R Drinking Water Page 1

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