The Facts Behind the Frack, Scientists weigh in on the hydraulic fracturing debate by Rachel Ehrenberg, September 8, 2012; Vol.182 #5 (p. 20), Society for Science and the Public
To call it a fractious debate is an understatement. … “People want it to be simple on both sides of the ledger, and it’s not simple,” says environmental scientist Robert Jackson of Duke University.
…
Does methane leak into water?
One of the most explosive issues, literally, is whether fracking introduces methane into drinking water wells at levels that can make tap water flammable or can build up in confined spaces and cause home explosions. Studies are few, but a recent analysis suggests a link. Scientists who sampled groundwater from 60 private water wells in northeastern Pennsylvania and upstate New York found that average methane concentrations in wells near active fracturing operations were 17 times as high as in wells in inactive areas. Methane naturally exists in groundwater — in fact, the study found methane in 51 of the 60 water wells — but the higher levels near extracting sites raised eyebrows. … A fourth possibility, which Jackson thinks is most probable, is that the cement between the well casing and the surrounding rock is not forming a proper seal. Cracking or too little cement could create a passageway allowing methane from an intermediate layer of rock to drift into water sources near the surface. Such cases have been documented. In 2007, for example, the faulty cement seal of a fracked well in Bainbridge, Ohio, allowed gas from a shale layer above the target layer to travel into an underground drinking water source. The methane built up enough to cause an explosion in a homeowner’s basement. Other types of gas and oil wells have similar problems, Jackson says, but fracking’s high pressures and the shaking that results may make cement cracks more likely. “Maybe the process itself makes it harder to get good seals,” he says. “We need better information.” Methane leaking into the air can also cause ozone to build up locally, leading to worries about headaches, inflammation and other ills among people who live nearby.
…
Is fracking fluid hazardous?
A typical fracked well uses between 2 million and 8 million gallons of water. … A report released in April 2011 by the House Energy and Commerce Committee did provide some chemical data: From 2005 to 2009, 14 major gas and oil companies used 750 different chemicals in their fracking fluids. … Twenty-five of these chemicals are listed as hazardous pollutants under the Clean Air Act, nine are regulated under the Safe Drinking Water Act and 14 are known or possible human carcinogens, including naphthalene and benzene. In addition to the fracking fluid, the flowback contains water from the bowels of the Earth. This “produced” water typically has a lot of salt, along with naturally occurring radioactive material, mercury, arsenic and other heavy metals. “It’s not just what you put into the well. The shale itself has chemicals, some of which are quite nasty,” says Raymond Orbach, director of the University of Texas at Austin’s Energy Institute. … The Energy Institute report cites one case in West Virginia in which about 300,000 gallons of flowback water was intentionally released into a mixed hardwood forest. Trees prematurely shed their leaves, many died over a two-year study period, and ground vegetation suffered.
…
Local geology in some areas may also allow fracking chemicals and produced water to seep up from deep below into water sources. … Local geology probably also played a role in fracking fluid getting into drinking water in Pavillion, Wyo., a site that has been at the heart of the fracking controversy.
…
Potential hazards
…
6. Home explosions If methane does get into the water table — because of cracked cement, local geology or the effects of old wells — it can build up in homes and lead to explosions.
SUGGESTED READING :
The EPA’s website on hydraulic fracturing
CITATIONS & REFERENCES :
S. G. Osborn et al. Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing. Proceedings of the National Academy of Sciences, May 17, 2011.
N.R. Warner et al. Geochemical evidence for possible natural migration of Marcellus Formation brine to shallow aquifers in Pennsylvania. Proceedings of the National Academy of Sciences, July 24, 2012.