Simplified conceptual diagram of hydrogeologic settings in south-central New York; adapted from Heisig and Scott (2013, fig. 10).
Although debunked for having nothing to do with natural gas development or hydraulic fracturing, anyone familiar with the internet has likely seen the now-famous clip of someone lighting tap water on fire in the activist documentary Gasland. In an effort to obtain baseline drinking water data in New York’s portion of the Marcellus Shale deposit, the US Geologic Survey conducted a study of 66 household wells that found elevated levels of naturally-occurring methane.
“This study provides baseline water-quality data that will be useful for decision makers, regulators, industry, and stakeholders concerned about water quality,” USGS scientist Paul Heisig, who led the study, said in a statement.
The New York State government and Governor Cuomo have been slow-playing a decision on whether to allow hydraulic fracturing. Perhaps these study results are one of the pieces of information the administration has been waiting for in order to help inform its regulatory decision with regard to the controversial natural gas well completion technology.
USGS conducted the testing in June and July of 2012 to provide baseline data on methane groundwater concentrations in roughly 2000 square miles of prospective Marcellus Shale gas acreage. “All wells were at least 1 mile from any known gas well (active, exploratory, or abandoned),” according the study.
Map showing locations of valley areas and sampled water wells in south-central New York; adapted from Heisig and Scott (2013, fig. 4).
“Methane levels varied by more than five orders of magnitude across the study area covering parts of Broome, Tioga, Chemung, Chenango, and Delaware counties. The samples most likely to contain high methane concentrations were from the valley wells that tap into bedrock groundwater lying beneath glacial clay deposits. More than 50 percent of such samples contained methane at or above the 10-milligrams-per-liter monitoring level. Like a cap on a soda bottle, clay blocks methane gas from escaping into the atmosphere.
Nearly 30 percent of groundwater samples from valleys tested at or above the recommended monitoring level — no samples from wells in uplands exceeded that level. Methane in valley groundwater was mostly thermogenic in origin, derived over millions of years by processes deep within the earth that produce fossil fuels. In contrast, methane found in upland groundwater was mostly generated by bacteria.” – Paul M. Heisig and Tia-Marie Scott, USGS
