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10 June 1999 <br /> AGE-NC Project No 97-0290 <br /> Page 12 of 26 <br />' high sandy silt content, potentially making SVE an effective remedial method in the vadose zone <br /> One negative aspect of SVE is that not all contaminated zones of soil are remediated effectively or <br /> at the same rate For example, a sandy soil zone will cleanup more quickly than a silty one SVE is <br /> not usually effective in soil with high clay content Other drawbacks of SVE include ineffective <br /> treatment of soil lying below ground water or within the capillary fringe or "smear" zone and <br /> ineffective treatment of longer-chain hydrocarbons Ground water remediation should be conducted <br /> concurrently with SVE to facilitate remediation of the smear zone <br />' 715 Duration <br /> Cleanup periods for soil vapor extraction typically range from several months to several years Based <br /> upon the volume of impacted soil, hydrocarbon concentrations and the predominance of larger- <br /> grained soils (sands, silty sands) at the site, 6 to 12 months are estimated for the duration of <br /> remediation of a majority of the volume of soil Additional remediation time (4 to 8 months) is <br /> estimated to be required for remove hydrocarbons from the finer-grained soils <br /> 7 16 Estimated Cost Of Soil Vapor Extraction <br />' The costs for installation,operation and general maintenance of SVE systems varies,depending upon <br /> the particular system utilized for destruction of the extracted hydrocarbon vapors (thermal <br /> destruction, carbon adsorption, etc ) and the established cleanup goals The total cost to operate, <br /> sustain, monitor and sample a SVE system could vary from $40,000 00 to $100,000 00 per year <br /> 72 EX-SITU TREATMENT OF IMPACTED SOIL <br /> rHydrocarbon-impacted soil can be excavated and treated on-site or transported off-site for <br /> recycling/disposal On-site treatment alternatives (ex-situ) include aeration, bioremediation, vapor <br /> I extraction, and thermal destruction All are feasible methods for above-ground remediation of soil <br /> contaminated with gasoline Off-site disposal generally involves the transportation of the impacted <br /> soil to a licensed treatment/disposal facility <br /> 7 2 1 Excavation <br /> • All of the mentioned methods of ex-situ treatment require excavation of the impacted soil, which is <br />' generally an effective method for soil remediation Once excavated, the impacted soil is generally <br /> Advanced GeoEnvironmental,Inc <br />