Evaluation of Impacts to Underground Sources of Drinking
Water by Hydraulic Fracturing of Coalbed Methane
United States „ . ^T A. , c,^ , „. , „
Environmental Protection Reservoirs; National Study Final Report
Agency
Summary
EPA has published a final report summarizing a study to evaluate the potential threat to underground
sources of drinking water (USDWs) from the injection of hydraulic fracturing fluids into coalbed
methane (CBM) production wells. As in its August 2002 draft report, EPA has concluded that
additional or further study is not warranted at this time. In making this decision, EPA reviewed more
than 200 peer-reviewed publications, other research, and public comments. The Agency has
concluded that the injection of hydraulic fracturing fluids into CBM wells poses minimal threat to
USDWs.
In its review of incidents of drinking water well contamination believed to be associated with
hydraulic fracturing, EPA found no confirmed cases that are linked to fracturing fluid injection into
CBM wells or subsequent underground movement of fracturing fluids. Further, although thousands of
CBM wells are fractured annually, EPA did not find confirmed evidence that drinking water wells
have been contaminated by hydraulic fracturing fluid injection into CBM wells. Where fluids are
injected, EPA believes that groundwater production, combined with mitigating effects of dilution and
dispersion, adsorption, and biodegradation, minimize the possibility that chemicals included in
fracturing fluids would adversely affect USDWs.
In the course of conducting the study, EPA found that diesel fuel, which may pose some environmental
concerns, was sometimes used in fluids for hydraulic fracturing within USDWs. To address any
environmental concerns, EPA worked with the three service companies that perform 95% of the
hydraulic fracturing projects in the U.S. to voluntarily remove diesel fuel from CBM fracturing fluids
injected into USDWs. The three companies agreed and signed a Memorandum of Agreement (MOA)
to that effect in December 2003.
Background
Coalbed methane is a gas contained in varying quantities within all coal. Hydraulic fracturing of
production wells is technology that has been used for more than 50 years in conventional oil and gas
production to enhance recovery by enlarging fractures through which oil and gas, including CBM, can
be drawn to a well and pumped to the surface. Water-based fluids have become the predominant type
of CBM fracturing fluids; although fluids can also be based on oil, methanol, or a combination of
water and methanol. After fluids are injected to expand fractures within a coal seam, large quantities
of ground water and some of the injecting fracturing fluids are pumped out of the well to facilitate the
production of CBM. Additional technical information on the practice of hydraulic fracturing can be
found in the final report.
In 1997, in LEAF v. EPA, the Eleventh Circuit Court ruled that, because hydraulic fracturing of
coalbeds to produce methane gas is a form of underground injection, Alabama's EPA-approved
underground injection control (UIC) program must effectively regulate this practice. In response to
the Eleventh Circuit's decision, citizen complaints, and Congressional interest, EPA made the
determination to investigate the potential for hydraulic fracturing of CBM wells to contaminate
USDWs.
-------
In addition to reviewing more than 200 peer-reviewed publications, EPA also interviewed 50
employees from state or local government agencies and communicated with approximately 40 citizens
who were concerned that CBM production impacted their drinking water wells. EPA made a draft of
the report available for a 60-day public comment period in August 2002. Comments received from
more than 100 commenters, including private citizens, environmental and citizen groups, government
agencies, oil and gas companies, and trade associations, have been summarized in a Response to
Comments document that is available on the EPA website.
For More Information
The final report and a Response to Comments document can be found on the EPA website at
http ://www. epa. gov/safewater/uic/cbmstudy .html. The Memorandum of Agreement to remove diesel
fuel from hydraulic fracturing fluids and general information about the UIC program are available at
http ://www. epa. gov/safewater/uic.html.
Environmental and Public Health Benefits
This notice does not impose any new regulations, information collection, or record-keeping burden on
the public or other entities. The publication of the final report will not change the environmental or
public health benefits of the UIC program.
Office of Water (4606M) EPA 816-F-04-017 June 2004 www.epa.gov/safewater
------- |