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05 May 1997 <br /> AGE-NC Project No 95-0173 <br />' Page 22 of 29 <br />' A concern with air sparging is precipitation of iron, which can cause clogging of sparging points <br /> Laboratory analysis of Iron at the site Indicated that iron concentrations in ground water at the site <br /> are adequate for IAS <br /> Based on the guide How to Evaluate Alternative Cleanup Technologies For UST Sates (October <br /> 1994) published by the United States Environmental Protection Agency (EPA)Office of UST's, IAS <br />' is generally effective when permeability rates are greater than 10'(Exhibit VII-11) Results of the <br /> fate evaluation analysis Indicated that permeability conditions at the site are adequate for air sparging <br /> activity <br /> 815 Duration <br />' Air sparging in highly permeable aquifers generally results in rapid reduction of volatile 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 24 months for shorter-chain <br /> hydrocarbons <br /> 8 1 6 Cost <br /> Installation of an in-situ air sparging system will require the installation of sparging and extraction <br /> wells, piping system and equipment Setup costs would likely range from $30,000 to $40,000 <br />' Sparging equipment maintenance and monitoring would range from $5,000 to $10,000 annually <br /> ` Based upon a treatment period of 24 months, the total costs would be in the range of$35,000 to <br /> $50,000 <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 /> 82 GROUND WATER EXTRACTION <br /> 8 2 1 Basic Principles <br /> There are several different methods for treatment of extracted ground water, which are collectively <br /> called "pump and treat" As the name indicates, all methods 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 maintain capture <br />' Advances Geo£nirsronmental,Inc <br />