Using a newly developed stream-based environmental monitoring system, researchers from the US Geological Survey (USGS) and Penn State University found methane at high levels along a stretch of a Pennsylvanian stream situated in close proximity to the site of a recently reported shale gas leak. This environmental monitoring system could potentially be of great value as a screening tool for conducting environmental assessments of the impacts associated with extracting shale gas by hydraulic fracking.
After analyzing several water samples collected from Sugar Run, a stream flowing through Lycoming County, the scientists found evidence of methane in groundwater inflows similar to that found in natural gas. The findings were recently published in Environmental Science and Technology.
Susan Brantley, a professor of geosciences at Penn State and co-author of the paper, finds it startling that after monitoring 15 streams, one instance of shale gas degassing has already been observed that could legitimately be explained by a known gas well leak sited nearby.
After finding high concentrations of methane in Sugar Run, the researchers were also informed that several surrounding domestic water wells had reportedly been contaminated due to a defective cement casing of a nearby shale gas well.
Upon conducting further analyses on the methane in the stream, the authors found characteristics that were common to that of leaking shale gas well. Unfortunately, as the researchers do not have access to baseline water samples from Sugar Run, they are unable to prove that the methane in the stream originates from the leaking gas well. However, the findings show how stream monitoring can be used as an efficient and effective method of monitoring the environmental impacts of fracking.
"We hope this new technique developed by the USGS can now be used as a way of monitoring stray gas not only when it gets into drinking water, but when it gets into streams, which are much easier to access than homeowner wells," said Brantley. "In addition, streams collect water from nearby areas and may be very cost effective waters to target for monitoring because they integrate over larger land areas."
Monitoring has up until now been largely restricted to water wells that supply domestic drinking water. But according to the researchers, because water wells can be spread out, particularly in rural settings, this limits the effectiveness of assessing the real impact of gas drilling operations. Water (and the chemicals in them) flows into streams from watersheds; thus sampling the streams enables us to detect leaks that would otherwise be impossible to trace.
Victor M. Heilweil, Paul L. Grieve, Scott A. Hynek, Susan L. Brantley, D. Kip Solomon, Dennis W. Risser. Stream Measurements Locate Thermogenic Methane Fluxes in Groundwater Discharge in an Area of Shale-Gas Development. Environmental Science & Technology, 2015; 150330072215005 DOI: 10.1021/es503882b