Gas, termed “shale gas,” is tightly contained in shale gas formations, which are situated considerably deeper underground than traditional natural gas reserves. With hydrofracking, a well is horizontally drilled deep into the ground and its walls are sealed with cement. Fracture fluids, a proprietary combination of water, chemicals, and sand, are then forced down the well at a very high pressure, to force open seams, cracks, or “fractures” in the shale formation. The fractures allow the gas to escape where it is captured and stored for eventual commercial use. Each hydrofracking job requires approximately three to eight million gallons of water and most wells undergo hydrofracking many times. A portion of the fracture fluids, which pick up chlorides and other naturally occurring constituents, such as radioactive materials from the formation, remain below the surface. The rest of the wastewater flows back up the well, and is managed in a variety of ways, based on state regulations.
Most of the concern is about hydrofracking’s potential impact on aquatic resources and human health. Concerns range from direct impacts, such as contamination of drinking water and aquifer depletion, to more indirect (and possibly less likely) threats, such as the possibility that use of the procedure could trigger earthquakes in some regions. The majority of concerns are associated with protection of drinking water supplies. A number of public interest organizations have attempted to identify the chemicals used in the hydrofracking process. According to Earthworks, hydrofracking fluids may include hazardous chemicals such as biocides, diesel fuel, acids, metals, ethylene glycol, corrosion inhibitors, and other chemicals. Well known Great Lakes scientist and advocate Theo Colburn, currently head of the Endocrine Disruption Exchange, collaborated with the Environmental Working Group, to analyze samples of hydrofracking fluids. The analysis showed that of the more than 300 suspected hydraulic fracturing chemicals used in Colorado, at least 65 are federally listed hazardous substances and little is known about the rest.
Although this is disputed by the energy industry, there are also concerns that contamination of deep aquifers from a fracture(s) could occur which could also contaminate drinking water supplies, either through the wellbore (the hole produced when drilling an oil or gas well) or from cross contamination by hydrofracking fluids that spread up and out into adjacent aquifers. This is alleged to have happened in numerous high profile incidents (none of them in the Great Lakes). There has also been at least one blowout (an uncontrolled release of oil or gas, relatively uncommon with current controls) linked to hydrofracking.
Additionally, the oil and gas industry, producers of hydrofracking fluids, and regulators deny that hydrofracking can cause groundwater contamination. However, in August 2009, EPA officials admitted that underground drinking water contamination in Pavilion, Wyoming might be due to hydrofracking chemicals. Also, an 18-month study of the practice by ProPublica, an investigative public interest organization, found more than 1,000 cases of water supply contamination from the management of hydrofracking fluids.
To date, there are no documented cases of groundwater contamination problems in the Great Lakes, but use of the procedure is rapidly increasing and is on a “fast track,” with proponents calling shale gas the next big U.S. energy boom.