A study released by a team of Penn State scientists found evidence that groundwater near a shale gas well in Bradford County, Pennsylvania was tainted by chemicals used in hydraulic fracturing and drilling for natural gas. The study suggests the chemicals traveled through sideways cracks in the ground.
The study was published in the Proceedings of the National Academy of Sciences.
One of the authors, Susan Brantley, distinguished professor of geosciences at Penn State, said the results were the first to show chemicals used in drilling migrating through rock formations. And they went a good distance—1 to 3 kilometers.
"We really laid out all the data and showed that it did move through the rock at shallow and intermediate depths, and it moved a long way,” Brantley said.
The study used well water data collected on behalf of three families who sued Chesapeake Energy, after the company drilled a series of faulty wells near them in late 2009. They settled with the company for $1.6 million, but refused to sign non-disclosure agreements.
Shortly after the wells were drilled, the homeowners began complaining about bubbling and cloudiness in their water. Some had foaming in their water “like shaving cream,” Brantley said.
The Pennsylvania Department of Environmental Protection (DEP) investigated; it found natural gas had migrated into the groundwater and cited the company.
Based on these and other violations, Chesapeake agreed to a consent agreement with the DEP in May 2011, agreeing to pay a $700,000 civil penalty and to donate $200,000 to the DEP’S Well Plugging Fund.
The consent agreement stated that Chesapeake “failed to properly case and cement the gas wells and to prevent the migration of gas into sources of fresh groundwater.”
Eventually, Chesapeake tried to fix the problems by further cementing the wells.
The families wanted data analyzed
As part of their settlement with Chesapeake, the three families agreed to sell their homes to the driller. Crucially, they refused to sign the non-disclosure agreement, which would have prohibited them from sharing the results of their water tests with anyone, including scientists.
After the final settlement, Garth Llewellyn, a hydrogeologist with Appalachia Hydrogeologic & Environmental Consulting, which conducted water tests for the plaintiffs, contacted Penn State scientists to see if they would analyze the water. Llewellyn was the lead author of the study.
“There were clearly other issues here. There was unnatural foam discharging from these wells,” said Llewellyn. “We wanted to investigate further.”
The Penn State scientists, who got support for the study from the university and the National Science Foundation, found chemical compounds similar to those found in fracking wastewater. They also found 2-n-Butoxyethanol—2BE—a chemical used in drilling fluid and in the hydraulic fracturing fluid for some of the wells drilled by Chesapeake. The chemical is found in more than 100 products used in hydraulic fracturing, according to the EPA, which lists the chemical as a possible “indicator of contamination” from fracking activities.
The study found nearby gas drilling activities were “the likely cause” of the contamination.
In an emailed statement, Marcellus Shale Coalition spokesman Travis Windle said the industry has improved "through important technological advancements" in the years since the wells in question were drilled.
The authors admit their conclusions have limitations.
"It is not possible to prove unambiguously that the (chemicals) and 2-BE were derived from shale gas-related activities," the paper states. It added that no chemicals "were detected above regulatory drinking water standards."
Theories on how wells could have been contaminated
Brantley said even if the water didn’t exceed drinking water standards, what came out of the private wells was alarming.
“I’m a geologist—I don’t think you would want to drink this water—if for no other reason than it was foaming,” Brantley said.
Importantly, the authors didn't think the chemical got in the groundwater from fracking itself, because the salts that are so prevalent in the Marcellus Shale were not present in high concentrations in the water they tested.
They have two basic theories for how the contamination got into the wells. The company may have hit a fault while drilling the well, and the chemicals traveled more or less horizontally through the fault to the aquifer. Or it could have leaked out of a surface storage pit nearby.
The steel and cement casing for the wells only went down about 1,000 feet. Below that, the well bores were open rock. Brantley believes it was through this open part of the wells that the chemicals may have escaped.
She added that it appeared that safeguards put in place since the wells were drilled may make this type of contamination less likely. In 2011, the state increased its casing requirements, including provisions that required companies to better protect groundwater and prevent gas migration into coal bed seams.
Windle, of the Marcellus Shale Coalition, reiterated this point: “Pennsylvania’s regulations were dramatically strengthened over the past several years—from overall well construction practices, including enhanced casing and cementing requirements, to expanded pre-drill testing, and heightened surface containment measurements—aimed at protecting groundwater.”
'An example of one of many mistakes'
Terry Engelder, a professor of geology at Penn State, said the study was more of a look back at how drilling was conducted in Pennsylvania in the early stages of the gas boom.
"This is an example of one of many mistakes that industry made early on," said Engelder.
He thinks the problems may have occurred during the drilling stage.
"At least initially, all wells are drilled as open holes — and you have to make the hole in the ground before you can put casing in and put cement in," he said. "I think it’s the notion of the authors, and I concur with this, that whatever happened, happened drilling through the water table."
Engelder says this type of occurrence is exceedingly rare — he knows of only three such events in the more than 9,000 wells drilled in the Marcellus.
"It's not common," he said. "But it has happened. It's imperative on industry to minimize those events. Even three events in thousands of wells that have been drilled is still too large."