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27 December 1996 <br /> AGE-NC Project No 95-0143 <br />' Page 15 of 19 <br />' involves removal of volatile organic compounds from ground water by promoting the transfer of <br /> contaminants from the dissolved phase to the vapor phase Carbon adsorption utilizes granular <br /> activated carbon to simply "filter" organic compounds out of ground water <br />' A third, but less common method of above-ground treatment of water is bioremediation <br /> Contaminated ground water is "treated" by adding hydrocarbon-degrading microbes or by <br />' augmenting natural hydrocarbon degradation activities with the introduction of nutrients <br /> 6 2 3 FEASIBILITY TESTING <br /> Aquifer testing has not been performed at the site However, sand is present from approximately 3 <br />' feet above to 15 feet below ground water surface <br />' There are several disadvantages to "pump and treat" methods The most serious disadvantages <br /> include 1) extended cleanup periods, resulting in increased total costs, although the maintenance <br /> for this method is relatively cost-effective and 2) regulatory cleanup goals are rarely attainable, <br /> mostly due to persistent hydrocarbons detected in subsequent sampling events Ground water <br /> extraction is generally not a desirable method for remediation However, this technology is useful <br /> for hydraulic control to prevent spreading of the contaminant plume <br /> I <br /> 6 2 4 DURATION <br />' Experience has shown that all systems involving ground water extraction require much more time <br /> than would be anticipated from aquifer tests and calculations of ground water discharge rates, and <br />' seldom achieve regulatory goals for ground water clean-up Systems typically operate for several <br /> years During this time,pumps and other equipment may need replacement several times Currently, <br /> the primary utility of pump-and-treat systems is in control migration of contaminated ground water <br /> 6 2 5 COST <br /> Ground water extraction is usually a very costly method of ground water treatment Costs for <br /> installation of a"pump and treat" system typically ranges from $25,000 00 to $40,000 00, including <br /> the installation of one or more large-diameter extraction wells Once extracted, the contaminated <br /> water must be treated or disposed Treatment is highly dependant upon the concentrations of <br />' dissolved hydrocarbons in the ground water For the Chase Chevrolet - Van Buren site, the cost per <br /> gallon could be as great as $2 00, based upon the extractionAtreatment of approximately 600,000 <br /> gallons of contaminated ground water Costs for the entire treatment project would likely be between <br /> I <br />