Editor’s note: This is another in a series of articles by the Orange County Commission for the Environment. Each article highlights an environmental issue of interest to the residents of Orange County. The CFE is a volunteer advisory board to the Board of County Commissioners. Additional information can be found in the Orange County State of the Environment 2014 report at http://nando.com/2v2.
Certain geologic basins in the United States have deposits of organic-rich shale containing reserves of natural gas and oil. Extraction of hydrocarbons from these shale deposits has become fairly widespread using horizontal drilling and hydraulic fracturing, or “fracking.” In North Carolina, organic-rich shale deposits occur in rocks of Triassic age; basins that contain Triassic rocks exposed at the surface are shown here. Only the Sanford sub-basin has been proven to contain organic shale.
Only a very small portion of southeastern Orange County is underlain by the Triassic-aged Deep River Basin. This basin is composed of three sub-basins; from north to south they are the Durham, Sanford, and Wadesboro sub-basins. The central portion of the Sanford sub-basin contains an approximately 800-foot-thick deposit of organic-rich shale. Limited activity to date identified potentially commercially viable natural gas resources in a 59,000-acre (92-square-mile) portion of the Sanford sub-basin in Lee County and a portion of Chatham County.
In 2011, the N.C. General Assembly directed several state agencies to investigate implications of horizontal drilling and fracking for oil and natural gas production in North Carolina. The resulting North Carolina Oil and Gas Study was published in 2012. In addition, the General Assembly overrode then-Gov.r Perdue’s veto, thus legalizing fracking for natural gas extraction once regulations governing these activities were developed. Regulations governing horizontal drilling and fracking were developed and as of March 2015 applications for the permits necessary to drill for natural gas in North Carolina have been available. As of September 2015, no drilling unit applications or complete oil or gas well permit applications have been received by the state.
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While direct adverse effects from fracking are unlikely in Orange County, nationwide shale-gas exploration and exploitation demonstrate that the fracking process involves activities that could result in adverse impact, including the following:
▪ Possible contamination of surface water and groundwater;
▪ Negative impacts to water supplies;
▪ Wastewater disposal issues;
▪ Negative air quality impacts;
▪ Negative infrastructure impacts; and
▪ Detrimental social impacts common to boom and bust economies
If drilling for natural gas from nearby shale deposits occurs, the likely impacts on Orange County would be indirect, though not insignificant. The water used for fracking that is not recycled would need to be disposed of. This water would likely be trucked to a wastewater treatment plant, possibly in Orange County. Wastewater plants may not be able to test for and remove the contaminants found in return water, leading to the possibility that contaminants could be discharged into local waterways. Increased heavy truck traffic could cause damage to county roadways and bridges.
The low price and large supply of domestic natural gas, as well as the significant amount of gas known to exist in much larger shale deposits elsewhere in the United States, make extraction activities in North Carolina unlikely in the near term. Fracking within Orange County is even more unlikely since Triassic rocks are limited to the southeastern portion of the county. Were drilling to occur in shale deposits some 30 miles south of Chapel Hill, indirect impacts on water supplies and transportation infrastructure could take place in Orange County.
Learn more about fracking and North Carolina geology: