Methane gas is highly mobile in groundwater and travels far beyond the shale wells where it is drilled, according to a recently published study from the University of Guelph based Institute for Groundwater Research.
Explosive and therefore a safety risk, methane gas also changes the chemistry of groundwater, causing the quality to deteriorate.
The research, published in the journal Nature Geoscience, says methane will also escape into the atmosphere as a powerful greenhouse gas, potentially contributing to climate change.
To test the effects of methane in groundwater, the researchers injected the gas into a shallow sand aquifer for 72 days, and then monitored it for eight months at Canadian Forces Base Borden in Ontario.
“If this water is extracted, say, by a farmer, the dissolved gas can be released and form an explosion risk or change the taste of the water,” said G360 director and principal investigator Beth Parker in a University of Guelph press release.
Although the study only found small changes in water quality, it only covered a short time period with small amounts of methane. The scientists suggest large methane leaks could have a severe impact.
“For larger leaks over longer times and greater areas, these findings would indicate that the groundwater would become unusable,” said Aaron Cahill, a former U of G post-doctoral researcher now at the University of British Columbia.
Cahill explained that leaking wells could pose a significant risk to the environment: “Methane is 30 times more potent than carbon dioxide at trapping heat when in the atmosphere, so we need to consider both the air and the groundwater when monitoring for leaks. The impact to groundwater is likely to be long-term and persist long after a methane leak is fixed,”
U of G School of Engineering adjunct professor John Cherry, who co-authored the study, said more needs to be done to monitor groundwater for methane leaks.
“The industry needs a level playing field where the rules and reasonable expectations are clear. The gas will spread up and out in groundwater, so it is the responsibility of government to set science-based groundwater monitoring standards for all companies to meet.”