The Chemical Recipe
California’s Fracking Fluids: Contamination of drinking water: mechanisms are clear, but data are lacking
There are several ways that fracking fluids can potentially contaminate drinking water, and a number of cases of actual contamination have been reported (Hildenbrand et al 2015, Llewellyn et al 2015, EPA 2015b). However, the impact of hydraulic fracturing on water resources nationally is impossible to quantify because of the lack of data. Few studies exist, and the recent EPA report said it could not conclude “the frequency of impacts with any certainty” because it lacked access to water quality data or the needed data did not exist. What little data are available point to the following sources of possible contamination:
- Surface spills. Again, data are lacking. Existing estimates of the number of spills of hydraulic fracturing fluids nationally range from 100-to- 3,700 a year (EPA 2015b). The EPA found that most chemical spills resulted from equipment failures or leaks from storage containers (EPA 2015b). An extensive groundwater study in the Barnett Shale region in Texas found a pattern suggesting that some of the identified contaminants likely came from surface spills (Hildenbrand et al 2015).
- Well casing failures. There are estimates that well casings fail in up to 12 percent of new wells within the first year of operation (Ingraffea et al 2014). These failures may result in underground contamination of aquifers well outside of the immediate production zone.
- Migration of fluids. A report by the U.S. Geologic Service last year concluded that “new pathways can be created when injection pressures are applied during well stimulation,” allowing fracking fluids to migrate underground over significant distances (USGS 2014).
- Improper handling of wastes. In California, an ongoing investigation of thousands of improperly approved injection wells for oil and gas wastewater is producing troubling findings. On May 15, 2015, the oil and gas division submitted new information to the EPA identifying 53 injection wells that could potentially contaminate drinking and irrigation water, and an additional 207 wells that might affect potential drinking water sources (Bishop and Bohlen 2015). In May 2015, the Sierra Club and the Center for Biological Diversity sued the oil and gas division to stop the illegal wastewater injections.