Hydraulic Fracturing (fracking)
In non-technical terms, a fracking well is established as follows. A traditional fossil fuel well is drilled and extended horizontally through a formation of rock determined to hold, for example, natural gas (for cross cut image of the process see, Cross sectional image, fracking). After the well is drilled, holes are blown in the drilling pipe sections. A high pressure mixture of chemical and sand is injected into the well and exits the holes blown through the pipe into fractures in the rock formation. This high pressure mixture expands the fractures, and after the fracking fluid is pumped from the well, the fractures are held open by sand pumped into the well. This process allows the collection of fossil fuels that are widely disbursed in rock formations rather than in large pools of fossil fuels underground.
The chemical mixture pumped into the wells is contaminated with a number of toxic chemical (see below). When those chemicals are pumped from the well, they are either stored on site (for photo see, Fracking waste lagoon) or transported for storage. The content of the fracking waste varies from one manufacturer to the next, and the toxic contents of the waste removed from any particular fracking site depends on the chemical composition of the fracking liquid injected into the site. However, this process also causes the fracking chemicals to be contaminated with natural sediments that include heavy metals, increasing the danger posed by the fracking waste. The content of fracking chemicals varies from company to company, and those chemical has been treated as proprietary properties of each manufacturer, meaning that they are not required to report the exact mixture of those chemical to regulators (for discussion see fracking fluid). There is much controversy surround the content of fracking fluids and the ecological consequences of injecting those fluids into deep wells due to the environmental hazards they present, including treats to underground water supplies (e.g., see Cupas, 2008; Gordella et al., 2013).
In addition to threats posed by the storage of expended fracking fluids, the process of fracking requires the use of large quantities of water, and thus may cause a disruption in the availability of water in the areas in which fracking is employed. Depending on well size, between 2 and 8 million gallons of water are required. In Pennsylvania, one of the most heavily fracked locations in the Marcellus Shale region, there are 6,634 wells as of September, 2014 (for map of wells in Pennsylvania and count of number of wells, click HERE). Mathematically speaking, those wells required the use of between 13.3 billion to 53 billion gallons of water, which is now polluted and unusable. An important question that fracking raises, therefore, is whether this practice will eventually either pollute or consume so much water as to damage ecosystems and affect water access for humans.
Fracking has also lead to a number of environmental violations under the Clean Water Act in the US. As an example of the number of violations, click HERE to see a count of violations in Pennsylvania.
As noted, fracking is controversial for a number of reasons. In addition to environmental pollution and ecological destruction associated with fracking, the process of fracking has also been linked to seismic activity, including earthquakes. This potential relationship has been discussed in the academic literature at least since the early 1990s (Davis and Frohlich, 1993).
The fracking controversy is not restricted to the US (for a nontechnical summary of the US Congressional Report on fracking see, Congress). Hydraulic fracking was, for example, suspended in the UK between June, 2011 and April, 2012, following the report of minor earthquakes in fracking areas, and allowing time for the Royal Academy of Engineers to examine this issue. In the UK, fracking has been highly regulated in an effort to avoid some of the problems experienced with fracking in the US. In the US, Vermont has banned the use of hydraulic fracturing. In 2013, the State of New York passed a two year ban on fracking. A list of bans on fracking in other locations may be found here ( BANS).
Fracking remains an unfolding environmental controversy.
Cupas, A. C. (2008). Not-So-Safe Drinking Water Act: Why We Must Regulate Hydraulic Fracturing at the Federal Level, The. Wm. & Mary Envtl. L. & Pol’y Rev., 33, 605.
Davis, S. D., & Frohlich, C. (1993). Did (or will) fluid injection cause earthquakes?-criteria for a rational assessment. Seismological Research Letters, 64(3-4), 207-224.
Gordalla, B. C., Ewers, U., & Frimmel, F. H. (2013). Hydraulic fracturing: a toxicological threat for groundwater and drinking-water?. Environmental Earth Sciences, 70(8), 3875-3893.