Drinking water containing potentially hazardous concentrations of methane has been found near natural gas extraction sites, a new study shows.
In the northeastern US, it’s becoming increasingly common (though still controversial) to extract natural gas locked deep inside shale rock.
Called hydraulic fracturing, or fracking, this involves injecting a huge amount of water and chemical-laced fluids to fracture underground rock formations at high pressures, releasing the tightly bound methane within.
The practice has only become economically viable in recent years. According to the Energy Information Administration, the amount of gas produced from deep shale formations doubled between 2009 and 2010; and by 2035 fracking is projected to account for some 47% of US gas production.
The team, led by Robert Jackson of Duke University, analyzed samples of drinking water from 60 private wells above the Marcellus Shale in Pennsylvania and the Utica Shale in New York.
They discovered 17 times more methane, on average, in water from shallow wells within 1 km (or 3,000 feet) of active gas drilling areas than in water from other places.
Although methane concentrations in drinking water aren't regulated, says Jackson, the gas readily comes out of solution and is an asphyxiation and explosion hazard.
The higher levels are also in the flammable range. “I watched one homeowner light his water on fire,” Jackson says.
The chemical signatures of methane in the drinking water were consistent with the deep underground sources recovered by drilling and fracking.
The cause? The team suspects leaky well casings or fissures in the deep rock caused by the fracking process. However, they didn’t find any evidence of the fracking fluids themselves in any of the drinking water wells.
Industry groups are criticizing the study, noting that there is no "baseline" before-and-after data and no proof drilling wells caused the methane contamination.
Jackson found it “surprising how little peer-reviewed data there is” on well water contamination near shale gas drilling. And while he concedes that the study doesn’t have baseline data, he says the correlation between drilling and contamination is strong.
"It's pretty difficult to understand for me without that being the cause," he says. "There's not much difference between them except for drilling."
In a separate release, the team recommends more sampling before and after shale gas drilling over a broader area. They also suggest that governments require disclosure of chemicals in fracking fluid and that Congress should order federal regulation of fracking under the Safe Drinking Water Act.
More news to come for sure… a moratorium on fracking operations in New York state is about to expire on 30 June.
The study was published today in the Proceedings of the National Academy of Sciences.
Image by heraldo via morgueFile
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