New Study Confirms, Yet Again, Higher Rates of Methane Contamination in Water of Homes Near Frack Well Sites

A new study released this month by Duke University has found that water supplies located near frack wells (within 1 km) contain, on average, six times the level of methane than homes further away.  The study summarizes water testing results from 141 Pennsylvania homes, including results from 60 homes previously reported in an earlier Duke study.

While the new study essentially confirms the findings of the earlier research, for those non-wonks out there who haven’t read either, here are a few important take-aways: 

  • More Methane Contamination Near Frack Wells – As mentioned, while tests found methane at homes both near and far from frack wells (82% of all the homes sampled contained water with dissolved methane), homes within 1 km of a frack well had methane concentrations six times higher on average.  Furthermore, of the 12 homes where the concentration of methane was greater than the federal threshold for immediate remediation, 11 homes were within 1 km of a frack well (the twelfth was only 1.4 km away). 
  • More than Methane Was Found – The study also found ethane and propane in many of the water supplies tested.  Where ethane was found, the concentrations, on average, were 23 times higher at homes within 1 km of a frack well than at homes located further away.  And in the ten homes where propane was found, all ten of them were within 1 km of a frack well. 
  • The Results Suggest the Contamination Comes from Fracking Operations – Gas can either be produced by bacteria that naturally live in underground water sources (“biogenic” gas) or it can come from underground geologic formations like the Marcellus (“thermogenic” gas).  The presence of ethane and propane is associated with thermogenic gas, but not biogenic gas.  As such, the finding of ethane and propane in the tested water supplies - together with the fact that the gases tested had other qualities similar to Marcellus gas - strongly suggests that the presence of gas is likely due fracking operations.* 

Because Pennsylvania does not require pre-drill water testing, and has only recently encouraged such testing within 2500 feet (0.76 km) of a gas well, researchers did not have enough information to make a definitive link between the heightened gas levels in groundwater and nearby gas drilling.  Overall, however, the Duke researchers were very blunt about the likely sources of the contaminants: poorly constructed gas drilling wells. Specifically, they stated: 

“The two simplest explanations for the higher dissolved gas concentrations that we observed in drinking water are (i) faulty or inadequate steel casings, which are designed to keep the gas and any water inside the well from leaking into the environment, and (ii) imperfections in the cement sealing of the annulus [i.e. the well bore] or gaps between casings and rock that keep fluids from moving up the outside of the well.”

The report also warned that if faulty casings were responsible, “stray gases could be the first sign of contamination, with less mobile salts and metals from the formation waters or chemicals from the fracturing fluids potentially coming later.”

In the end, while the report highlights that more research is needed, it provides important new evidence that poorly regulated gas drilling can, and does, contaminate drinking water supplies, underscoring the critical need to further evaluate and understand the threats before moving forward with fracking.  What’s at stake—clean water and the health, property, and well being of local residents—is simply too important to risk.

  * Additionally, along with distance from gas wells, the study looked at the distance of home water supplies from “valley bottom streams” or the “Appalachian Structural Front”—two other factors suggested as having an influence on the presence of gas in groundwater.  Of the three, only proximity to gas wells was found to be significantly correlated with gas contamination.

About the Authors

Daniel Raichel

Staff Attorney, New York program

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