THE CONTROLS OVER THE NATURAL OCCURRENCE OF METHANE IN POTABLE GROUND WATER IN THE APPALACHIAN BASIN
Methane naturally is common. In NE Pennsylvania, measureable dissolved methane occurred in 24% of samples with 3.4% naturally exceeding the PADEP methane notification level of 7 mg/L. In the western area, dissolved methane occurred naturally in 36% of groundwater sampled and in Ohio, 4.1% of samples exceeded the Ohio dissolved methane action level of 10 mg/L. More methane occurs where hydrogeochemical facies types trend towards Na-Cl and Na-HCO3 type waters in valleys and along hill flanks. However, we found no relationship between the concentration of methane and proximity to pre-existing gas wells. Finally, concentrations of methane in domestic wells can vary by factors, depending on pumping regime and time of year.