The latest explosion in the extraction of Natural Gas from Marcellus shale deposits throughout Chautauqua County is a threat to the Lake's water quality. This is an excerpt from The League of Women Voters of Pennsylvania Marcellus Shale Natural Gas Extraction Study, 2009-2010, Study Guide II, Marcellus Shale Natural Gas:
Environmental Impact. This document can be downloaded at: http://palwv.org/issues/MarcellusShale/Marcellus%20Shale%20Study%20Guide%20II%20-%20Environmental%20Impact.pdf
Water Contamination
Water quality can be compromised at several stages of Marcellus Shale natural gas extraction. Gaining access to the proposed well site involves building access roads for the heavy equipment to transport the drilling rig, pipe, and water. Both transporting material to the site and site preparation can cause erosion and subsequent silting. Drilling through aquifers can contaminate water supplies. Approximately 15,000 gallons of chemicals are added to the fresh water for fracing (Soeder &Kappel, 2009). This water/chemical mix can leak onto the ground. The drilling slurry also contains cuttings of the native rock, which in the case of Pennsylvania’s Marcellus Shale, includes uranium (Shultz, 1999, p. 792). The flowback that comes to the surface at the drill site is fracing fluid – complete with dissolved minerals and added chemicals.
To avoid contaminating drinking water aquifers, drillers use cement casings to surround the drilling pipe. The first, a 24" conductor casing, goes thirty to sixty feet down to the drinking water aquifer. Starting again at the surface, a twenty inch casing is extended 200 to 500 feet through the coal bearing seams, preventing leakage into the aquifer. A third casing, 13-3/8", is cemented from the surface down to 1,000 feet, passing through shallow sandstones and shales containing natural gas and brine. If necessary, a 9-5/8" cement casing is extended down to seal off more shallow oil, natural gas, or brine. The final casing, 5-1/2", is cemented to 500 feet above the Marcellus Shale (Range Resources, n.d., 56-57). In Pennsylvania, two percent of conventional natural gas wells drilled have resulted in contamination.
If a water supply is suspected to be contaminated it is the responsibility of the user to report the problem to the Department of Environmental Protection (DEP) for investigation within six months of the completed drilling. If found at fault, the drilling company is responsible for providing water to the user for an indefinite period of time. In Pennsylvania the burden is put on landowners to show damage to water supplies by drilling. Therefore it is important for landowners to require drillers to have their water tested by a certified laboratory before drilling begins. Legislation has been introduced in the PA General Assembly to lengthen to two years the period to report problems after completion of drilling.
The frac fluid or flowback removed from the well after hydrofracing, contains chemicals used by the company to facilitate gas recovery from the shale and subsequent gas flow in the pipe. The chemicals used may include oils, gels, acids, alcohols, and various man-made organic chemicals. Because fluids injected into wells are specifically excluded from the 2005 Safe Drinking Water Act, states must provide regulations. In Pennsylvania, as of October 2008, all hydraulic fracturing companies must list the chemicals they use for fracing on their drilling permits. However, the proportions of each chemical used are considered proprietary information. The flowback is also site specific and some may contain diverse contaminants such as low levels of radioactive radon released from the underground rock formation. This flowback also contains hydrocarbons, heavy metals, and very high levels of total dissolved solids (TDS). TDS can include calcium, potassium, sodium, chloride, and carbonate. Because of its geology, Marcellus shale flowback tends to include more TDS than the flowback from other shale gas wells (Kelly, August 25, 2009). Before disposal, it is necessary to treat drilling wastewater appropriately.
Another important issue is the connection between water quantity and water quality. For example, taking water for drilling and fracing from a small stream rather than a large lake or river places a relatively increased burden on plant and wildlife within its limited ecosystem. Further, if fracing fluid is released into a small stream, the chemicals will not be diluted sufficiently to avoid damaging fragile ecosystems and harming aquatic life.
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