Duke University released today a study of methane contamination of water wells, finding that gas drilling has contaminated some water wells with methane. The study also concludes that frack fluids have not contaminated water wells. See http://today.duke.edu/2011/05/hydrofracking?utm_source=Twitter&utm_medium=Tweet&utm_campaign=Duke+Today
The Duke findings are consistent with DEP findings that gas had migrated from some drilling sites to water wells, but that no case of frack fluids returning from depth to contaminate water wells had happened in Pennsylvania.
The Duke University study looks at 68 water wells in 5 counties, with Bradford and Susquehanna counties in Pennsylvania a main area of inquiry. Samples of the water wells were taken in July and September 2010.
The study concludes that methane contamination of a water well is 17 times more likely if the water well is within 1 kilometer of gas drilling.
When I served as Secretary of the Department of Environmental Protection, DEP documented cases of gas migration from Marcellus wells around Dimock in Susquehanna county and in Bradford county.
Duke also finds that the gas migrating is thermogenic and is not biogenic gas or gas that is encountered when a water well itself is sunk. This too is consistent with DEP conclusions.
DEP furthermore found that the gas that was migrating in the Dimock area was Devonian gas located at about 1,000 to 3,000 feet. Devonian gas is above Marcellus gas. DEP concluded that the Devonian gas had not been isolated as a result of poor drilling practices.
Bradford and Susquehanna counties have had many more gas migration problems than counties in Southwest Pennsylvania. Had Duke University done this study in Washington, Greene, and counties in the Southwest it would have reached different conclusions. The reasons for the geographic difference in the incidence or rate of gas migration include geological differences in the counties, quality of gas drilling in the respective areas, or some of both.
In the case of 19 water wells contaminated by methane from drilling around Dimock, 14 of the 19 had methane removed by December 2010. DEP required the drilling company to plug and repair gas wells that reduced the gas migration. At some water wells there were measurable declines in methane contamination shortly after gas wells were repaired or plugged.
Furthermore a settlement in December 2010 between DEP and the drilling company required payments to the families near Dimock where gas had contaminated their water wells that averaged $200,000.
DEP also proposed new gas drilling rules in 2009 that became final in February 2011. The new rules raise standards for the design, construction, and operation of gas wells to reduce gas migration pollution.
Gas migration has been a problem in Pennsylvania for decades, well before the first Marcellus well was drilled in 2005. The new, strong rules and the attention to this problem make this the time to reduce it sharply.