Hydraulic fracturing is a process by which pressurized water, sand and chemicals are pumped into natural-gas wells more than a mile deep to break apart shale to release pockets of oil and natural gas.



Researchers hypothesized that methane concentrations in the drinking-water wells they sampled would increase over time with the growth of natural gas drilling in the area. This is a correlation researchers observed in Pennsylvania’s Marcellus Shale region.



But that’s not what UC’s water tests revealed. The study concluded that methane observed in groundwater was “biogenic,” or naturally occurring and independent of natural gas drilling.



“The study researchers in Pennsylvania thought the contamination issue was a failure of the well casings in the fracking wells,” Townsend-Small said.



“Hopefully, that doesn’t happen often. And that apparently didn’t happen with the wells of homeowners we worked with for our study.”



Townsend-Small has spent much of her career researching groundwater and methane. She and other UC geologists are studying the influence of the Great Miami River on groundwater in southwest Ohio at UC’s C.V. Theis Groundwater Observatory. She also has studied atmospheric methane in relation to algae blooms in the Great Lakes and methane in arctic lakes in Alaska.



“Some people had elevated concentrations of methane in their groundwater, but the isotopic composition showed it wasn’t from natural gas. It was from a different source,” Townsend-Small said. “What we found is in most cases it was probably from underground coal in the area or biological methane produced in groundwater.”



Study co-authors included UC professor emeritus David Nash and UC assistant professor of geology Joshua Miller.



Botner said if researchers were to replicate the study, she might recommend expanding it to include other hydrocarbons such as propane or look for carbonate isotopes associated with natural gas drilling.



“It’s a controversial topic,” Botner said. “But that’s why science is so valuable. Maybe another study would confirm our findings or maybe they would find something else. Regardless, we would welcome more well testing.”



