MDN In-depth: Duke University Study Links Marcellus Shale Gas Drilling with Methane Contamination of Water Wells

A peer-reviewed study by Duke University researchers claims to show a link between natural gas drilling in the Marcellus Shale that uses horizontal drilling with hydraulic fracturing and an increased level of methane (natural gas) in water wells that are within 1,000 feet of the drilling. The report, titled “Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing,” was published Monday online in the Proceedings of the National Academy of Sciences. A full copy of the five page report is embedded below so you can read it for yourself.

Duke researchers tested 68 water wells in Pennsylvania and New York, finding elevated levels of methane in 85% of the wells.

When they fingerprinted the methane – comparing the chemistry of the methane in the wells with that from natural gas wells in the region – “the signatures matched,” said Robert Jackson, a professor at Duke and a study author.

“At least some homeowners who claim that their wells were contaminated by shale gas extraction appear to be right,” he said.

The authors said it was the first “systematic evidence” of methane contamination of private drinking wells in areas where gas extraction is occurring.

The testing occurred in July and September, mostly in the northeastern Pennsylvania counties of Susquehanna and Bradford, but also in Wayne and Lackawanna, plus Otsego County in New York.*

What they did and did not find in their testing:

They did not find evidence of well-water contamination from fracking fluids or from the flow-back water, which contains high levels of salts and other contaminants, including radioactivity, that are naturally occurring in the Marcellus Shale formation.

But in at least nine wells [13 percent of the wells tested], they found methane at levels exceeding what the U.S. Department of the Interior calls an “action level,” indicating that the wellhead should be vented immediately.*

Researchers did not show how methane was getting into the water wells, but offered three possibilities:

  1. It’s happening naturally.
  2. It’s happening through new cracks caused by hydraulic fracturing.
  3. It’s happening via leaky gas well casings—problems with the protection drillers put in place to protect the bore hole from the surrounding water aquifer.

The researchers believe option #3 is the most likely cause—that’s their “best guess.”

Potential problems with this new study

Already news of the study has been picked up and trumpeted by more than 400 media outlets nationwide. It’s early days yet, but there’s been no real coverage of any challenges to the study. MDN offers the following observations:

(1) The study supposedly shows a link between shale gas drilling, ie horizontal drilling that uses hydraulic fracturing, and high levels of methane in water supplies located within 1,000 feet of said drilling. But a number of the water wells Duke tested are in Otsego County, NY, some 100 miles from the nearest horizontal/hydraulically fractured well—nowhere near 1,000 feet of any fracked gas drilling. In MDN’s review of the report, it’s not apparent why water wells located in a place where there are no fracked gas wells would be used. Perhaps the Otsego water wells are used as a “control” of some sort? If Duke found high levels of methane in any of the Otsego wells, it would strongly argue that the methane is naturally occurring and has nothing to do with gas drilling. MDN would like to know more about the Otsego wells tested.

(2) By the Duke researchers’ own admission (read the report), methane in water is not a health hazard. If there’s methane in the water, you don’t die or even get sick from drinking it. However, Duke says “it is an asphyxiant in enclosed spaces and an explosion and fire hazard.” So the whole point of the study is not that you’ll get sick from it, but you may have an explosion from it (if high levels of methane are indeed happening).

(3) The data sample of 68 drinking water samples is a very small sample, from just a few locations. To make broad, sweeping general conclusions from such a small data set is not good science. A larger study with more locations would be needed to prove conclusively gas drilling is causing an increase in methane levels in water supplies.

(4) Perhaps the biggest problem with this study: There were no baseline numbers to begin with. That is, methane is known to have been in water supplies for generations—it’s not uncommon. There are areas of the country where methane naturally rises to the surface—how do you think it was discovered in the first place? Do the locations where the Duke sampling was done have high levels of naturally occurring methane? We don’t know because the researchers have not established it. It could very well be the answer is “no,” but the problem is, you just don’t know. Sloppy science, sloppy results.

Is this agenda-driven science?

Tipoffs that this may be agenda-driven science, and not truth-seeking science, include two policy recommendations made in the study:

1. Consider regulating hydraulic fracturing under the Safe Drinking Water Act. That is, put the federal Environmental Protection Agency (EPA) in charge of something it has no business being in charge of: gas drilling/mining. This has been the drumbeat from those who oppose drilling—they hope to shut it down by using the “back door” of the EPA to do it.

2. Fully disclose chemicals used in hydraulic fracturing. Nothing wrong with that (in MDN’s opinion). But the study itself said it detected no chemical contamination from gas drilling in any of the water wells it tested—only high levels of methane. So if there’s no chemical contamination and the industry is doing fine with keeping chemicals out of water supplies, why regulate it? Why offer a policy recommendation about something that was proven to be absent by your own research? Makes no sense.

What do you think about the new study? Leave us a comment.

*Philadelphia Inquirer (May 10, 2011) – Duke study finds methane in well water near gas drilling sites