EPA Releases Draft Assessment of the Potential Impacts of Hydraulic Fracturing on Drinking Water Resources
June 6th, 2015
Written by Sig Silber
On June 5 the U.S. Environmental Projection Agency (EPA) issued a document for public review regarding their study of the possible negative impacts of what is commonly called fracking. They found some impacts, identified potential impacts but generally concluded that fracking was not a major threat to the public's drinking water supply. It appears that the small number of adverse events can be further reduced by attention to best practices.
The draft, which is meant for comments and does not yet represent the official policy of the EPA, was in response to:
"The U.S. Congress urged the U.S. Environmental Protection Agency (EPA) to study the relationship 14 between hydraulic fracturing and drinking water. This report synthesizes available scientific literature and data to assess the potential for hydraulic fracturing for oil and gas to change the quality or quantity of drinking water resources, and identifies factors affecting the frequency or severity of any potential changes. This report can be used by federal, tribal, state, and local officials; industry; and the public to better understand and address any vulnerabilities of drinking water resources to hydraulic fracturing activities."
Key excerpts from the Executive Summary follow:
"From our assessment, we conclude there are above and below ground mechanisms by which hydraulic fracturing activities have the potential to impact drinking water resources. These mechanisms include water withdrawals in times of, or in areas with, low water availability; spills of hydraulic fracturing fluids and produced water; fracturing directly into underground drinking water resources; below ground migration of liquids and gases; and inadequate treatment and discharge of wastewater.
We did not find evidence that these mechanisms have led to widespread, systemic impacts on drinking water resources in the United States. Of the potential mechanisms identified in this report, we found specific instances where one or more mechanisms led to impacts on drinking water resources, including contamination of drinking water wells. The number of identified cases, however, was small compared to the number of hydraulically fractured wells."
Impact of Surface Spills
There are several mechanisms by which a spill can potentially contaminate drinking water resources. These include overland flow to nearby surface water, soil contamination and eventual transport to surface water, and infiltration and contamination of underlying ground water. Of the 151 spills characterized by the EPA, fluids reached surface water in 13 (9% of 151) cases and soil in 97 (64%) cases. None of the spills of hydraulic fracturing fluid were reported to have reached ground water.
Impact of Faulty Well Integrity
"Impacts to drinking water resources from subsurface liquid and gas movement may occur if casing or cement are inadequately designed or constructed, or fail. There are several examples [Author's Note: "Several" means four.] of these occurrences in hydraulically fractured wells that have or may have resulted in impacts to drinking water resources. In one example, an inner string of casing burst during hydraulic fracturing, which resulted in a release of fluids on the land surface and possibly into the aquifer near Killdeer, North Dakota. The EPA found that, based on the data analysis performed for the study, the only potential source consistent with conditions observed in two impacted monitoring wells was the blowout that occurred during hydraulic fracturing (U.S. EPA, 2015j). In other examples, inadequately cemented casing has contributed to impacts to drinking water resources. In Bainbridge, Ohio, inadequately cemented casing in a hydraulically fractured well contributed to the buildup of natural gas and high pressures along the outside of a production well. This ultimately resulted in movement of natural gas into local drinking water aquifers (Bair et al.. 2010; ODNR, 2008). In the Maman Creek gas field in Colorado, inadequate cement placement in a production well allowed methane and benzene [Author's note: From the summary alone I could not tell the source of the benzene but benzene in drinking water is not good and thus this might be the most serious incident they studied - Natural gas in water is not a health hazard and is fairly common] to migrate along the production well and through natural faults and fractures to drinking water resources (Science Based Solutions LLC, 2014; Crescent, 2011; COGCC, 2004). These cases illustrate how construction issues, sustained casing pressure, and the presence of natural faults and fractures can work together to create pathways for fluids to migrate toward drinking water resources."
The full report can be here and in the Executive Summary here. Reading the Executive Summary is important in order to understand the limitations of this study as explained by the EPA. Information on the process for finalizing this report and public participation can be found here.