Newest Duke Study: Higher Methane Levels in Water Wells closer to Drilling

A new study out of Duke University, released today by the journal Proceedings of the National Academy of Sciences finds that people living closer to Marcellus gas wells have a higher chance of getting methane - and other chemicals - in their drinking water than people living farther away. This new study expands and confirms findings of an earlier Duke study two years ago.

The team sampled 81 new drinking water wells in six northeastern Pennsylvania counties, and combined data with results from 60 previously sampled wells in PA and Otsego County, NY. Researchers found methane in drinking water of 82% of the 141 homes - and concentrations were six times higher in those homes that were within a kilometer of a gas well. A kilometer is 3280 feet. Currently, many gas companies test water wells within 1,000 feet of proposed gas wells. Clearly not far enough, given Duke's study.

Not only did those homes have higher methane than "allowable" levels, but they also had higher levels of ethane and propane. These are components of the deep gas that shale gas drillers seek, not "biogenic" gas from upper layers.

Fracking can Pollute Water .... Or Maybe Not

photo by Frank Finan

According to one media report, the newest study by Duke scientists (published on Monday) shows that gas drilling in northeastern Pennsylvania did not contaminate nearby drinking water wells with salty water.

But flip to a different paper and you learn that same study concludes that fracking does indeed put drinking water at risk from fluid migration.

The "truth" is more complex, and the study more nuanced. Introducing their paper, the Duke researchers mention that the drilling debate raises concerns about the potential for  methane, metal-containing brines and hydraulic fracturing fluids to migrate into drinking water aquifers. A critical question, they say, is whether there is any "hydraulic connectivity" between the deep shale gas formations and the overlying drinking water aquifers - and if so, to what extent.

Introducing their study the scientists say, "We present geochemical evidence from northeastern Pennsylvania showing that pathways, unrelated to recent drilling activities, exist in some locations between deep underlying formations and shallow drinking water aquifers." They show that salty water (brine) does indeed migrate, but is not correlated to the location of shale-gas wells.

"However," they add, "the presence of these fluids suggest conductive pathways and specific geostructural and/or hydrodynamic regimes in northeastern PA that are at increased risk for contamination, particularly by fugitive gases" because of the natural connections to deeper formations.So, yeah, the possibility of migration is there because the geology surrounding the Marcellus Shale is already fractured with pathways that could allow contaminants to move more freely than expected. You can read the study here.

Fortunately, the Department of Energy is conducting research that may provide some answers to the question of whether drilling fluids migrate and how far they travel. DOE researchers are working with a drilling company at a commercial well site in southwestern PA. The are adding tracing elements to hydro-fracking fluids and will conduct follow-up monitoring. They hope to see whether drilling fluids move upwards and/or sideways through the shale.



Using tracers isn't new - they're routinely used in hydrologic studies. Like the Duke study, the DOE tracer study will help researchers learn more about the geology surrounding the Marcellus shale. And like the Duke scientists, the DOE researchers caution that Marcellus geology is variable, changing from place to place.

Scientists Show Fracking Contaminates Drinking Water

Earlier this week PNAS published a study  that documents a link between hydraulic fracturing and water contamination. A team of Duke researchers showed that water wells located close to active drilling sites had methane levels 17 times higher than water wells located further away. Their definition of active drill site: within 3280 feet of a well.

The scientists tested 68 drinking water wells in the Marcellus and Utica shale drilling areas in northeastern Pennsylvania and southern New York State. They measured dissolved salts and other constituents (carbon, boron and radium) as well as methane levels.

The average methane concentration in drinking water was high enough – over 28 milligrams per liter (mg/L) – to qualify for hazard mitigation as recommended by the US Office of the Interior. But some water had much more methane – up to 64 mg/L.

Though the researchers did not find evidence of fracking chemicals in the water wells, they expressed concern for that they see is a clear correlation between drilling activity and methane migration into drinking water. The presence of methane demonstrates that pathways do exist for migration of other potential contaminants.

Even more interesting were the recommendations they made in a White Paper accompanying their study.

Research recommendations:

• Initiate a medical review of the health effects of methane.
• Create a national database listing methane, ethane and propane concentrations in drinking water.
• Find out how methane is getting into drinking water, say the scientists. Is methane contamination due to poorly constructed well casings? Or is the process of fracking creating pathways for methane and other chemicals to migrate to the surface?
• Develop better estimates for greenhouse gas emissions of methane associated with shale gas extraction.
• Conduct extensive baseline water testing prior to exploration and drilling. They recommend testing water at least 3,000 feet from well sites and that testing be conducted by independent state-certified labs.
• Better study of waste treatment. For drilling fluids going to wastewater treatment facility, regulators need to understand how much of the chemicals are removed in the waste treatment plants and what are the long-term ecological effects downstream.

Policy recommendations:

• Regulate fracking under the Safe Drinking Water Act (SDWA).
• Fully disclose chemicals used in hydro-fracking.