Previous studies using very small sample sets reported that there may be higher concentrations of methane dissolved in groundwater near wells using hydraulic fracking methods in northeastern Pennsylvania.1,2
The new peer reviewed study by Syracuse University published in Environmental Science and Technology used a database of over 11,000 sites, hundreds of times larger than the previous studies. No statistically significant relationship was found between dissolved methane concentrations in groundwater from domestic water wells and proximity to pre-existing oil or gas wells. Previous analyses used small sample sets compared to the population of domestic wells available, which may explain the difference in prior findings compared to the new findings using over 10,000 data points.
A frequent cause of errors associated with small sample sets is a biased sampling procedure. Every researcher must seek to establish a sample that is free from bias and is representative of the entire population to minimize or eliminate sampling error. Another possible cause of this error is chance. The process of randomization is done to minimize sampling process error but it is still possible that all the randomized subjects are not representative of the population. The most common result of sampling error is when the results from the sample differ significantly from the results from the entire population, and the results from it will most likely differ from the results taken from the entire population.
In this new study the entire population is better represented and shows that the previous studies likely suffered from small sample set bias and were not representative of the entire population that showed no correlation between wells and proximity to groundwater, and showed no statistical significance between standard wells and wells that implement hydraulic fracking methods. Methane is a naturally occurring gas that is sometimes present in groundwater. It is harmless and dissociates with time, but is used as a signal for anti-fracking movement that other contaminants may be present.
Sen. James Inhofe recently stated that there has never been “an instance of ground water contamination” caused by hydraulic fracturing. A spokeswoman for Inhofe, Donelle Harder, clarified that “the physical act of cracking rocks through hydraulic fracturing, thousands of feet below ground, has never caused groundwater contamination. What we are not saying is that a surface spill, faulty casing, bad drilling practices cannot be a problem. There is a difference between the hydraulic fracturing process and rest of the well drilling process.” The out of touch on climate change skeptic seems to have gotten this one right.
Whether fracking is good or bad for the environment is a value proposition. As it stands now there is no connection between groundwater contamination and fracking. The anti-fracking movement needs to focus on facts and science to better support their cause, and stop their reliance on fear of the hypothetical. As a result of reliance on fear mongering instead of science the anti-fracking ideologs have given a bullet to the climate change skeptics and lost a credibility battle with Senator Inhofe hurting the environmental cause.
 Osborn et al. Proc. Natl. Acad. Sci. U. S. A. 2011, 108, 8172].  Jackson et al. Proc. Natl. Acad. Sci. U. S. A., 2013, 110, 11250].