Professional Engineers Of North Carolina

FALL 2014

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9 Fall 2014 the Professional Engineer rock. Te mix cracks open the fractures and replaces the voids with sand to allow natural gas to fow up the well. During the fracking process, 4-6 million gallons of excess water can come up the well to the surface. Te water is then reinjected — if it's clean enough to meet drinking water standards — and used as make-up water for another round of fracking. If the fracking water does not meet groundwater standards, then it is stored onsite in lined 1-5-acre ponds and eventually transported to ofsite treatment plants for treatment and disposal. (See the previous page for a representation of the items that are common at a fracking and horizontal drilling site.) Horizontal drilling is conducted after the vertical well casing is installed to increase the surface area where fracking can be applied, while minimizing the above-ground area that is afected by natural gas extraction. What is in typical fracking fuids, and should we be concerned? Typical fracking fuids are made up of approximately 99.5 percent water and sand. Te remaining 0.5 percent is most often anti-scaling or lubricant additives to promote the fow of the sand into the fractures. In general, most engi- neers with experience in fracking and resource extraction realize that the initial injection of fracking fuids does not provide substantial risk to groundwater because it is injected several thousand feet below the level of drinking water. At the same time, it is common to reinject the fracking return water to minimize the amount of water that must be treated. Te reinjection of the fracking return water can include fracking fuids and, potentially, hydrocarbons that come from below the ground. Te water quality of the fracking fuids and reinjection of the fracking return water are areas that require regulations, testing and enforcement requirements to protect groundwater resources. Tis typically requires professional engineering and/or professional geologist review. What are the potential risks associated with fracking for shale and natural gas? Te three main potential risks and problem areas from fracking and below-ground energy resource extraction include: 1. Potential for groundwater impacts due to faulty vertical well construction. Te installation and grouting of the vertical well casing often is the most difcult and critical aspect of the natural gas extraction process. Te integrity of the casing and grout installation in the multiple confning layers in a well used for fracking is something that demands special skills and inspection requirements. Potential solutions: Te following is a list of a few of the practical solutions that could be used to minimize groundwater impacts due to fracking: n Develop specialized mixes of bentonite and neat cement grout. n Require pressure checks of well casing after installation and prior to fracking. n Inspect liner systems for fracking water storage. n Require regular monitoring of methane leakage, if and when it occurs. n Initiate additional research by North Carolina universities for conditions that are unique to our state. 2. Potential for impact to above-ground natural resources. A typical natural gas extrac- tion well site requires three to fve acres of area to house the drilling equipment, water storage areas and appurtenance structures. Depending on where these well sites are located, they can negatively afect natural resources such as wetlands, streams and other environmentally sensitive areas. Special siting requirements often are required to protect natural resources from impacts due to well site construction. Potential solutions: Te following is a list of solutions that have been implemented in other states to minimize the impacts to natural resources: n Have a third-party, natural resource conservation group study, identify and locate the existing natural resources and protected areas and develop a geographic information system database that can be used during the siting process.

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