Scientific study confirms groundwater contamination by hydraulic fracturing
9 July 2013
For years companies engaged in high-volume, horizontal hydraulic fracturing, also known as hydrofracking or simply fracking, used for the extraction of natural gas and oil from shale deposits, have claimed that this process is safe for the environment and for people. The results of new research published in the online edition of the Proceedings of the National Academy of Sciences (PNAS, 24 June 2013) lend strong support to the conclusion that toxic chemicals associated with hydrofracking are leaking from gas wells into surrounding ground water.
This finding corroborates what has long been obvious based on numerous documented instances of contamination in the drinking water wells of homes near hydrofracking drill sites, including the famous video of a homeowner igniting the water pouring from a tap, due to the high concentration of dissolved natural gas. Despite this evidence, the energy companies have asserted that their methods preclude leakage into the near-surface ground water. The new research blows this claim apart.
Fracking involves drilling a vertical well many thousands of feet below the surface to reach deeply buried bedrock deposits of shale, which contain trapped natural gas or oil (petroleum). Once the formation has been reached, the drill turns horizontal and extends out along the shale deposit. So-called “fracking fluid”, a witch’s brew of water laced with a range of toxic chemicals, including known carcinogens, and sand, is injected down the well under high pressure. This fluid then spreads out along the horizontal bore and fractures the shale, releasing the trapped natural gas or oil. The resulting mixture is then returned to the surface via the vertical shaft. The gas or oil is separated out, leaving millions of gallons of contaminated water for each well.
Disposal of the contaminated wastewater is a significant problem in its own right, since most municipal wastewater treatment facilities are not equipped to handle the toxic chemicals, which sometimes even include radioactive elements drawn out of the bedrock. This aside, however, the industry has consistently claimed that a combination of metal pipes and cement casings for the vertical portion of the well prevents any leakage of toxic materials as they traverse the near-surface deposits that contain ground water. Hence, according to the companies, all claims that contamination of ground water is due to hydrofracking must be false.
The newly released study demonstrates that, with a very high degree of statistical confidence, the location of ground water contamination by gases associated with hydrofracking is correlated with the locations of fracking wells. The researchers analyzed samples from 141 drinking water wells located in northeastern Pennsylvania, an area of extensive hydrofracking activity. For those located close to natural gas wells (defined as less than one kilometer away), concentrations of methane, ethane, and propane were found to be significantly higher than for those water wells located farther away.
“Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006). Ethane was 23 times higher in homes <1 km from gas wells … propane was detected in 10 water wells, all within approximately 1 km distance.”
The researchers compared three proposed explanations for high concentrations of these chemicals in ground water—distance to gas wells and two alternatives, locations in valley bottoms and proximity to certain geologic formations (Appalachian Structural Front), both of which could be the sources of naturally occurring gases. Of these three factors, distance to gas wells was the only one that reached statistical significance, using two different analytical methods.
Chemical signatures of the gases also indicate that they are likely the product of hydrofracking rather than of alternate sources. In other words, the industry claim that hydrofracking does not cause contamination of groundwater has been refuted.
The implications for human health and the environment are substantial. Many of the hydrofracking chemicals are known carcinogens. It must be kept in mind that the study published in PNAS targeted only three chemicals, gases that are likely the product of the fracking process. Some previous studies have purported to show no leakage of fracking fluid chemicals from gas wells. However, the current finding that these three gases are escaping into the groundwater throws these earlier studies into question.
As the authors of the PNAS article point out, very little research regarding ground water contamination associated with hydrofracking has been carried out. The federal Environmental Protection Agency (EPA) has recently dropped a study of probable water contamination due to hydrofracking in Wyoming, passing it on to the state, which is even less likely to conduct an objective investigation due to pressure from the energy companies. Furthermore, the fracking fluid formulas are considered proprietary information by the drilling companies. Release of this information has been highly restricted, so researchers may not even know what chemicals to look for.
Studies of the health effects on people who live near gas wells have been limited as well, due to industry pressure and government suppression. In Pennsylvania, a law was passed that allows the contents of fracking fluid to be divulged to individual doctors treating their own patients, but prohibits them from sharing that information even with other doctors. This effectively prevents any epidemiological studies that might reveal broader correlations between the distributions of toxic chemicals and illness.
The authors of the PNAS study conclude that the contamination they document is likely the result of “… poor well construction.” This is hardly comforting, however. Given the substantial drop in natural gas prices over the last few years, at least at the wholesale level, due to the glut on the market caused by the massive increase in fracking, profit margins have declined significantly. Some companies have cut back production or switched capacity to the extraction of other hydrocarbons. Therefore, the pressure to keep production costs as low as possible is extreme. This inevitably leads to cutting corners. Even supposedly safe procedures can be compromised when profit is placed above safety. As seen in the BP disaster in the Gulf, the consequences can be severe.
In the case of hydrofracking, the probability of a single, highly visible accident may be less than it is in deep-water oil drilling, but the cumulative effect of leakage from thousands upon thousands of wells, unacknowledged by the industry, and ignored or covered up by the government, would be equally if not more devastating. The insidious contamination of ground water is less visible than a massive oil spill in the ocean. Nevertheless, the long-term effects could potentially impact even greater numbers of people given the large portions of the country where hydrocarbon-containing shale deposits suitable for fracking are found.
In order to overcome the depressed domestic price of natural gas, the industry is now pushing to develop an export market. Natural gas prices in Europe and Asia are higher than in the United States. Export, in the form of liquefied natural gas (LNG), would provide huge profit opportunities for the giant energy companies. Proposals are already being made for the retrofitting of existing LNG import facilities so they can be used for export. At least one such project is already in progress. Large-scale export would lead to an even greater expansion of hydrofracking in the US than already exists. The result would be the despoiling of large sections of the environment and the sickening of potentially millions of people in order for the energy companies to make super-profits.
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