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01 June 1999 <br /> AGE-NC Project No 95-0137 <br /> Page 20 of 26 <br /> ' 6 2 1 Ground Water Treatment Methods <br /> The documented presence of dissolved hydrocarbons will require treatment for the recovered water <br /> ' Two of the most common methods of water treatment are air stripping and carbon adsorption Air <br /> stripping involves removal of volatile organic compounds from ground water by promoting the <br /> transfer of contaminants from the dissolved phase to the vapor phase The process usually works well <br /> ' with volatile organic compounds, but less successfully with longer-chained hydrocarbons, such as <br /> commonly occur in diesel fuel Carbon adsorption utilizes granular activated carbon to simply <br /> "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 2 Feasibility Testing <br /> Aquifer testing has not been performed at the site However, sand is present from just below the <br /> ground water surface to 10 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 /> 1 <br /> 6 2 3 Duration <br /> ' <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 /> the method seldom achieves regulatory goals for ground water clean-up Systems typically operate <br /> for several years During this time, pumps and other equipment may need replacement several Mmes <br /> ' Currently, the primary utility of pump-and-treat systems is in control migration of contaminated <br /> ground water <br /> Advanced GeoEn,oronmental,Inc <br />