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15 February 2000 <br />' AGE-NC Project No 98-0448 <br /> Page 18 of 33 <br />' gained through laboratory analysis, the measured permeabilities at the site were 2 x 10-' cm/s and <br /> 3 x 10'8 cm/s Results of the laboratory analysis indicated permeability conditions at the site are <br /> adequate for SVE <br />' Based on geologic cross sections(Figures 3 and 4), soil beneath the former UST area has a relatively <br /> high silty sand content in the upper thirty-five feet,where permeability was 2 x 10-'cm/s,potentially <br />' making SVE an effective remedial method in thevadose 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 may have to be <br /> conducted concurrently with SVE to facilitate remediation of the smear zone <br /> I <br /> 8 15 Duration <br /> Cleanup penods for soil vapor extraction typically range from several months to several years Based <br /> upon the volume of impacted soil,hydrocarbon concentrations and the presence of finer-gramed soils <br />' (silty sands, sandy silts and clayey silts) at the site, 12 to 24 months are estimated for the duration <br /> of remediation <br />' 8 16 Estimated Cost Of Soil Vapor Extraction <br />' The costs for installation,operation and general maintenance of SVE systems vanes, 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 an SVE system at this site could vary between $30,000 00 and <br /> $60,000 00 per year <br /> 1 <br /> 82 EX-SITU TREATMENT OF IMPACTED SOIL <br /> Hydrocarbon-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 />' 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 /> I 5 <br /> Advanced GeoEnvnronmental,Inc. <br /> I <br />