The natural-gas-drilling surge is polluting groundwater, but that doesn't mean the controversial practice of hydraulic fracturing is to blame. At least not directly.
That's the conclusion of a new paper from researchers at several universities, published in the Proceedings of the National Academy of Sciences, who studied movement of gases in Texas and Pennsylvania regions with lots of gas drilling.
They found that problems with gas-well construction, not fracking itself, is letting gases escape and reach drinking-water wells in some cases.
"In general, our data suggest that where fugitive gas contamination occurs, well-integrity problems are most likely associated with casing or cementing issues. In contrast, our data do not suggest that horizontal drilling or hydraulic fracturing has provided a conduit to connect deep Marcellus or Barnett formations directly to surface aquifers," states the paper from researchers with Ohio State, Duke, Stanford, Dartmouth, and the University of Rochester.
The researchers found drilling-related contamination in eight clusters of drinking water-wells in Pennsylvania's Marcellus Shale region and the Barnett Shale in Texas. Those are two of the places where gas production has boomed thanks to the marriage of horizontal drilling and fracking, which involves high-pressure injections of water, sand, and chemicals that create fissures in rock formations to enable trapped energy to flow.