The study also found a correlation between detectable hydrocarbons and proximity to shale gas wells that had been cited by the Pennsylvania Department of Environmental Protection for health and safety violations.
None of the detected levels of hydrocarbons in 64 samples taken from Bradford, Susquehanna and Wayne counties between May 2012 and June 2014, included significant levels of hydrocarbons. All the samples were below 200 parts per billion, which is considered a trace amount.
“Our data is telling us that [the hydrocarbons] are coming from the top down,” said Brian Drollette, lead author on the study and a graduate student at Yale University’s chemical and environmental engineering department. “It’s probably resulting from surface spills near the hydraulically fractured sites.”
The researchers looked for two different types of organic compounds, including those in the gasoline range, as well as those in the same chemical family that includes diesel. They also looked for 54 volatile organic compounds, such as benzene, toluene and ethylbenzene.
The team, led by researchers at Yale University, wanted to find out if there were any detectable levels of hydrocarbons associated with hydraulic fracturing in residential water wells, or if there were some other natural sources of contamination. Methane migration has been linked to poor well casing, but natural sources of methane can also be present in aquifers.
Paul Ziemkiewicz, director of the West Virginia Water Research Institute and who was not involved in this research, says it’s a “good, sound study” that adds to the growing body of literature about the impact of shale gas drilling on water quality.
“I don’t think too many people have looked at the actual migration pathways of organic compounds,” said Ziemkiewicz.
He’s conducted his own research, and says the link to surface spills, rather than upward migration of frack water, confirms his own study conclusions.
“That’s what I’ve been saying for the past five years,” said Ziemkiewicz. “My point has been all along that it’s mainly surface spills and illegal transport and dumping that are responsible for most of the contamination. And migration from the actual Marcellus level up to the surface is extremely unlikely.”
The West Virginia Water Research Institute, a program of the National Research Center for Coal and Energy at West Virginia University, serves as a statewide vehicle for performing research related to water issues. WVWRI is the premiere water research center in West Virginia and, within selected fields, an international leader.