This post highlights a statement, made in 2009, from numerous state regulatory bodies pertaining to water contamination and hydraulic fracturing.
These various organisations quoted here represent the state regulatory bodies for oil and gas development. In the US it is the states, rather than federal organisations, that play the main role in regulation of this sector.
You'll note that in every case, no contamination is reported from hydraulic fracturing. How does this square with the numbers I reviewed a few weeks ago, where there are cases reported, albeit very rare ones?
The answer lies in how one defines hydraulic fracturing. To a well engineer, hydraulic fracturing refers to the process of pumping fluid down the well and into the reservoir, in order to fracture the rock. No more, no less. However, to the public, "fracking" has come to mean all stages of shale gas extraction, from drilling and casing a well, to the actual fracturing of the rocks, to the storage, transport and disposal of waste fluids.
Where we have seen contamination issues (and again, if you look at the AP numbers, rather than the headlines, these are rare) they are not due to the hydraulic fracturing process itself, but other aspects of the drilling process. For instance, we have seen issues with well casing leading to buildup of stray methane in shallow aquifers. We have seen examples where storage of waste fluids in open pits has lead to leakage at the surface, and we have seen examples of illegal dumping of untreated waste.
I think this distinction is important, which is why I usually talk about "shale gas development" or "extraction" when referring to the whole process chain, saving "hydraulic stimulation" or "fracking" to use them as they are defined from an engineering perspective.
The distinction matters when it comes to look at the risks that shale development might pose in the UK. We can see in the reports from the various regulatory bodies that the fracking process itself does not pose a risk. The issues appear to be: how the well is drilled and the casing is cemented; and how waste fluids are stored, treated and disposed of.
This is crucial, because it removes the major unknown in the process as an issue - that while wells in the UK have been hydraulically stimulated, current shale proposals represent a scaling up of the existing process. We have abundant experience in the UK of handling, treating, transporting and disposing of all sorts of chemicals, and the existing industry handles plenty of produced water every year.
Similarly, we've drilled thousands of wells both onshore and offshore, and we know how to address casing and integrity issues, which are rare to non-existent. It matters not to the near surface casing integrity whether a well is being used for "high volume" hydraulic fracturing, "traditional" hydraulic fracturing, acidization, or any other completion activity.
Part of the public's fear over shale gas is that it seems like a novel process, and we are scared by what we don't know or understand. In fact, the statements from the US regulators show that the unknown part (the "fracking") does not pose much of a risk - the riskier parts are in fact the parts that we know most about, and that we have the most experience in mitigating, regulating and minimising.