Wastewater spills and disposal related to shale gas extraction ought to be given the same weight in policymaking as worries over contamination of groundwater by hydraulic fracturing, according to a report released today.

The report, by California-based Pacific Institute, adds to recent research suggesting that the process of fracking, in which shale deep underground is cracked using pressurized water and chemicals to release trapped hydrocarbons, is less likely to contaminate aquifers, and greater dangers lie elsewhere.

The report focuses on surface spills and leaks during production, improper well casings, wastewater disposal, water usage and air emissions. It is based on an extensive literature review, as well as interviews with 16 representatives from state and federal offices, industry and nonprofit groups.

Water withdrawals in drought-prone areas could be of significant concern, the report states, and U.S. EPA has likely underestimated the water needs of hydraulic fracturing in its estimate of 2.3 million to 3.8 million gallons per well. There is a large amount of variability in the water withdrawals, it finds.

For example, while less than 5 million gallons is needed in the Woodford Shale in Texas, the water consumption rises to 13 million gallons in the state's Eagle Ford formation. It can be difficult to estimate the lifetime requirements of the well given the uncertainty over how many times the well will be fracked.

And although water withdrawals may appear small when considering the resources of a state as a whole, the effect can be large at the local level, the report finds. Because the frack water cannot be reused and returned to the water cycle, it represents a consumptive use that can alter flows underground.

"In some cases, the water is taken from remote, often environmentally sensitive headwater areas, where even small withdrawals can have a significant impact on the flow regime," the report states.

Conflicts over usage have already occurred, including in Colorado, where oil companies competed with farmers for water rights, and in Ohio, where a water district suspended sales pending further research (EnergyWire, June 12).

The report recommends research on factors that dictate the amount of water needed to fracture a well, as well as an examination of the impacts of usage on water quality.

Other than usage, the report points to spills and leaks as a significant threat to water quality, including when wastewater is moved to disposal wells elsewhere.

Anecdotes suggest wastewater is regularly spilled en route to disposal wells, although no one keeps track of the information comprehensively, said Heather Cooley, author of the report and co-director of the water program at the Pacific Institute.

"There is a lack of data and information on where fracking is happening, where the wastewater is going, where it's being reused," she said.

Once the wastewater reaches disposal wells, it gets pumped underground. Since oil and gas waste is exempt from a hazardous waste classification despite the presence of radioactive minerals, it can be injected into Class II injection wells rather than Class I hazardous waste wells.

"Class II wells are subject to less stringent requirements than Class I wells and therefore disposal in Class II wells presents a greater risk of contaminating groundwater and triggering earthquakes than in Class I wells," states the report.

Click here to read the report.