Natural underground pathways could allow salts and gases from deep Marcellus Shale formations to migrate into shallow drinking water aquifers, according to a Duke University study.
The study found elevated levels of salinity with similar geochemistry to deep Marcellus brine in drinking water samples from three groundwater aquifers in northeast Pennsylvania, but the study showed no direct links between the salinity and shale gas exploration in the region.
“This is a ‘good news, bad news’ kind of finding,” said Avner Vengosh, professor of geochemistry and water quality at Duke’s Nicholas School of the Environment.
But the study further goes on to say that it does not appear that hydraulic fracturing caused the elevated salinity. The location of the samples containing brine don’t correlate with the location of shale gas wells, Vengosh said. The results are consistent with tests conducted in the 1980s prior to shale gas development. Hydraulic fracturing or fracking is a process in which sand, water and chemicals are pumped into shale at a high pressure to release the gas trapped within the rock thousands of feet underground.
The negative aspect of the study is the geochemical fingerprint of the salinity detected in well water from the Lock Haven, Alluvium and Catskill aquifers suggests a network of natural pathways exists in some locations, especially in valleys, according to the study. These pathways allowed gases and Marcellus brine to migrate up into shallow groundwater aquifers from deeper underground shale gas deposits.
“This could mean that some drinking water supplies in northeastern Pennsylvania are at increased risk for contamination, particularly from fugitive gases that leak from shale gas well casings,” Vengosh said.
Despite the study’s assertion that fracking at this point has not caused migration of salt and other chemicals, the fact remains that natural migration can occur shows the risk of fracking, said Ray Beiersdorfer, a geology professor at Youngstown State University.
“When ODNR and industry people first started coming around, they said migration was not possible, but now this survey shows it is occurring naturally,” he said.
Now the oil and gas companies use a process that created additional potential pathways for migration through the fracturing process, which will accentuate the problems that occur naturally, Beiersdorfer said.
The work that is going on underground includes a lot of theories, models and hypothetical information. The actions that have been ongoing underground because of fracking have not occurred as the models have suggested, he said. Fracturing rocks underground is not an exact science.
“There is a lot of unknowns and risks and for that reason I think that fracking should be banned,” Beiersdorfer said.
There are a lot of people in positions of authority who have been “willfully ignorant” to the potential problems. It is going to be the people who live in the area who suffer the consequences of drilling and deep injection, he said.
The Duke study reaffirms previous conclusions reached by experts across the country that, in fact, there is no link between hydraulic fracturing and contamination of water aquifers, said Dan Alfaro, spokesman for Energy in Depth, an oil and gas trade group.
“These findings serve as further confirmation of statements from EPA chief Administrator Lisa Jackson, the U.S. Department of the Interior and regulators from Harrisburg to Houston to Colorado to Columbus. Hydraulic fracturing is a safe and proven process and one with no proven risk to our groundwater resources,” he said.
The state of Ohio has thus far not had any groundwater contamination that can be linked to fracking, said Heidi Hetzel-Evans, spokeswoman for the Ohio Department of Natural Resources.
“Additionally we haven’t had any issues with surface water,” she said.
The most common water-related issues would be well-construction issues, Hetzel-Evans said.
Ohio requires well casing that is 50 foot below not just the deepest drinkable water, but 50 feet below the deepest water that could be used in the future with treatment, she said. The well casing is the first layer of protection for groundwater from drilling. The requirement is for casing to go down to 655 feet, which is more than 400 feet deeper than Pennsylvania requires.
The Duke team evaluated 426 samples from groundwater aquifers in six counties overlying the Marcellus Shale formation in northeastern Pennsylvania.