A new study has found that drinking water at hydraulic fracturing sites in northeastern Pennsylvania have increased levels of certain chemicals in groundwater. While the substances are not at dangerous levels, the findings suggest that underground disturbances from fracking could eventually result in water quality problems.
The researchers, from Columbia University’s Lamont-Doherty Earth Observatory and other institutions, found that both distance and topography play a role. In lowland drinking wells within one kilometer (about six-tenths of a mile) of a drill site, they found higher levels of dissolved calcium, chlorine, sulfates, and iron. In lowland wells more than a kilometer away, they found higher levels of methane, sodium, and manganese compared with equally distant wells on higher ground. Upland wells within a kilometer of a drill site showed no specific trends.
Hydraulic fracturing, fracking, involves injecting a pressurized mixture of water and chemicals into deep rock layers to release natural gas. Critics of the practice are concerned about the risk of groundwater contamination, the use of thousands of gallons of water which are forever contaminated, and the risk of leaking waste water containment pools. The fracking industry defends the practice as nothing new and as safe.
Lead author Beizhan Yan, a Lamont-Doherty geochemist, said, “The finding suggests increased mixing of different groundwater sources.” This could be due to several possibilities, he said. For one, the sudden, powerful pulses introduced by fracking might act like a pump, expanding and contracting subterranean spaces, and squeezing the contents around. This stress could propagate up to the surface and initiate mixing of groundwater, either from the sides or below, he said. The observations might also be due to leaky well casings at shallow depths, or spills of fracking fluids on the surface trickling down,” said Yan.
Fracking did not start up in northeastern Pennsylvania until 2007, but now the region has thousands of wells. Chillrud noted that pollutants can take years or decades to move into an aquifer. “If it’s from below, that could be an indicator that other, more problematic elements will be coming through at some point,” he said.
Coauthor Reynold Panettieri, a physician who directs Rutgers University’s Institute for Translational Medicine and Science, said none of the substances seemed to be at hazardous levels. However, he said, the different water chemistry nearer the fracking sites “seems to be a fingerprint of drilling. It gives us a map of hotspots that could potentially concentrate toxicants in the future.”
Paul Heisig, a hydrologist with the U.S. Geological Survey, said, “The study points out there may be some issues, but it really needs to be pursued with more data,” he said.