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' 10 June 1999 <br /> • AGE-NC Project No 97-0290 <br />' Page 19 of 26 <br /> influence was observed for air sparging at the site Additional sparging wells would be required for <br />' effective remediation of ground water The IAS method has been proven to be effective in many <br /> different soil types and at sites in California with varied ground water depths <br />' Soil in the saturated zone has a relatively high sand content,potentially making IAS effective for this <br /> zone Figures 4 and 5 depict cross sections, showing subsurface soil types at the site Results of the <br />' IAS pilot test performed at the site are summarized in Section 3 0 <br /> A concern with air sparging is precipitation of iron, which can cause clogging of sparging points <br />' Grab water samples sould be collected and analyzed for Iron,prior to initiation of air sparging <br /> Based on the guide How to Evaluate Alternative Cleanup Technologies For UST Sites (October <br />' 1994) published by the United States Environmental Protection Agency (EPA) Office of USTs, 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 /> Iactivity <br /> • 8 1 5 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 16 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 are likely to range from $30,000 to $40,000 <br /> Sparging equipment maintenance and monitoring would range from $5,000 to $10,000 annually <br /> I Based upon a treatment period of 24 months, the total costs would be In the range of$35,000 to, <br /> $50,000 ] t j 0/_ <br /> , 4 `'> <br /> r <br /> I 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 /> Advanced GeoEmironmeniai,Inc <br /> I <br />