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' 20 January 2005 <br /> AGE-NC Project No 97-0343 <br />' Page 16 of 21 <br />' 10 14 Feasibility <br /> Air-sparge testing has not been performed at the site Remediation of small dissolved ground water <br />' plumes requires the Installation of a few injection and extraction wells (already in place) An <br /> extensive piping network for Injection and extraction must also be Installed Air injection and <br /> extraction rates must be balanced to prevent the forced migration of contaminants In addition, a <br />' concern with air sparging is precipitation of iron, which can cause clogging of sparging points <br /> However, air sparging has proven itself as a very effective method for remediation of soil in the <br /> smear zone <br /> I <br /> 10 15 Duration <br />' Air sparging in highly permeable aquifers generally results in rapid reduction of hydrocarbon <br /> concentrations in the saturated zone Remediation times are generally comparable with soil vapor <br />' extraction times At the site,we estimate a remediation period of 12 to 1$ months for shorter-chain <br /> hydrocarbons Longer-chain (diesel) hydrocarbons have been detected in water samples collected <br /> at the site, and will require longer remediation periods If ground water remains at its current <br /> elevation,the fine grain unit directly above the ground water table may slow overall site remediation <br /> and hinder extraction of volatilized hydrocarbons <br /> 10 16 Cost <br /> Installation of an in-situ air sparging system will require the installation of several sparging wells, <br /> piping system and equipment Setup costs and the sparging equipment maintenance and monitoring <br /> would range from $30,000 to $35,000 depending on length of treatment period <br /> If air sparging is chosen for ground water remediation,vapor extraction will be used for vadose zone <br /> soil remediation Therefore,extraction equipment and monitoring costs would be included under soil <br /> vapor extraction estimates <br /> I10 2 GROUND WATER EXTRACTION <br /> There are several different methods for treatment of extracted ground water, which are collectively <br /> called "pump and treat" All methods of pump and treat involve extraction and transfer of <br /> contaminated ground water from the aquifer to an above-ground treatment or disposal/recycling <br /> facility The extraction is performed using an automatic pump system to establish and maintain <br /> contarninant capture characteristics in the aquifer and to assure that process volume requirements <br /> Advanced GeoEnviron mental,Inc <br /> I <br />