Energy Department researchers so far have found "nothing of concern" in a study of whether chemicals used in hydraulic fracturing for natural gas at one site in Pennsylvania traveled toward shallower groundwater.
The preliminary evidence, if ratified in a final report, would bolster claims by the industry that the boom in drilling doesn't pose risks to drinking water. Chances are low that fluids pumped more than a mile underground to free trapped gas could leak and contaminate drinking water, although that's not the only hazard from the practice known as fracking, said Fred Baldassare, senior geoscientist at Echelon Applied Geoscience.
"A lot of us never thought there was much of a risk of fluid migration,"Baldassare, a former Pennsylvania Department of Environmental Protection official, said toay in an interview. "We have so much confining pressure that the opportunity for water to move is just really minimal."
The other dangers include methane gas that can migrate through fissures toward the surface much more easily, he said. Also, surface spills or leaks from containment ponds holding water that flows back from a fracked well also are a risk, he said.
The Energy Department's study, which is still in progress and may be completed and released by the end of the year, is "far too preliminary to make any firm claims," Shelley Martin, a spokeswoman for the National Energy Technology Laboratory, said today in an e-mail. She declined to provide further information.
Richard Hammack, a scientist at the Pittsburgh lab involved with the study, didn't return telephone and e-mail messages. His statement that chemical-laced fluids remained thousands of feet away from drinking water supplies was published earlier today by the Associated Press.
"We are still in the early stages of collecting, analyzing and validating data," according to a statement today on the laboratory's website after the AP story was published.
Gas production in Pennsylvania surged in the past few years as companies expanded use of fracking, in which water, chemicals and sand are shot underground to break apart the rock and free the gas. The Marcellus Shale lies about 5,000 feet under in Pennsylvania, separated by thick rock layers from aquifers, which are at most a few hundred feet below the surface.
Still, a surge in fracking has been accompanied by complaints from homeowners who say their water has been contaminated, resulting in sick children, dead livestock and flammable tap water. Industry groups representing companies such as Cabot Oil and Gas Corp. say evidence has failed so far to establish a case of water contamination from fracking.
The Energy Department's laboratory in Pittsburgh is conducting studies of the safety of fracking at two sites in southwestern Pennsylvania, according to a fact sheet it released in April. According to the document, the lab used man-made tracers injected with the fracking fluids, and are now examining older, shallower gas wells to see if those tracers show up there. Those wells are themselves much deeper than drinking- water wells.
Hammack told the AP that so far the evidence shows that these tracers stayed below the shallower wells.