Update: Well water contamination near fracking operations

by Bill Chameides | October 25th, 2012
posted by Erica Rowell (Editor)

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It’s a match … again.

In May 2011, my colleagues at Duke’s Nicholas School of the Environment published a controversial paper on “Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing.” New information appears to corroborate the authors’ findings.

fracking schematic
Click on graphic for large image. (© Copyright 2010 Pro Publica Inc.)

Hydraulic fracturing, a k a fracking, as you might well know by now, refers to the use of horizontal drilling and hydraulic fracturing to exploit shale and other low-permeability formations that hold natural gas. A vertical well is drilled to the depth of the target rock (which in the case of the Marcellus Shale is often more than a mile below the surface) and extended horizontally along the gas-bearing formation. Water, sand and a mix of chemicals are then injected at high pressure into the well to split the rock and liberate the trapped gas. (See graphic at side and video below.)

In last year’s paper the Duke scientists reported that the data they had collected from 68 drinking water wells in Pennsylvania and New York indicated that drinking water in the vicinity of fracking operations was more likely to have higher concentrations of methane gas — and a specific form of the gas that looked like the same gas being extracted via fracking from the Marcellus Shale about a mile or more beneath the surface. Among the data they had to tie the well water to the shale gas was isotopic information: the methane in the wells had an isotopic signature similar to that of nearby shale gas wells.

No way, said the gas companies. In fact one company, Cabot Oil and Gas, in an attempt to discredit the Duke study, published an analysis in the industry publication Oil & Gas Journal demonstrating that the specific isotopic composition of the shale gas they pump is distinct from the methane found in drinking water wells.

But whaddya know? The Environmental Protection Agency also has data on drinking water and methane levels from in and around Dimock, Pennsylvania, data the agency left uninterpreted because of a change in its investigation and the complexity of isotopic “fingerprints.” But through a freedom of information request, Rob Jackson, one of the Duke scientists who co-authored the study, and colleagues obtained the isotopic data collected and analyzed earlier this year by EPA. The methane in some of the wells matches the methane in the gas Cabot is producing.


How fracking works

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