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06 December 1995 <br /> AGE-NC Project No. 95-0100 <br /> Page 12 of 13 <br /> 5.3.3, ESTIMATED COSTS FOR EXCAVATION <br /> At the Frankyln Cole site, impacted soil could not be excavated with standard excavating equipment. <br /> If disruption of site operations and space limitations mandate off-site disposal, the cost for excavation <br /> of impacted soil could exceed $200 per cubic yard. The cost could be as great as $240,000 for the <br /> removal of the estimated 1,200 cubic yards of hydrocarbon-impacted soil. <br /> 6.0. RECOMMENDATIONS FOR REMEDIATION OF HYDROCARBON-IMPACTED <br /> SOIL <br /> Based upon laboratory results of analysis of soil samples collected during this and previous <br /> investigations at the site, it appears that hydrocarbon impacted soil extend,, approximately 15 to 20 <br /> feet horizontally from the former dispenser area. The impacted soil appears to be distributed through <br /> the upper vadose zone, beginning at a depth of approximately 10 feet bsg and extending to a depth <br /> of 35 to 40 feet bsg. The hydrocarbon-impacted soil most likely extends under the building on the site <br /> - and possibly under Chrisman Road. <br /> As excavation is not feasible at the Franklyn Cole site, an in-silrr method should be considered. <br /> r Potentially, both in-.situ methods described in this CAP may be equally effective for remediating the <br /> site. From a cost basis, implementation of an insiru bioremediation program appears to be potentially <br /> less expensive than implementation of a soil vapor extraction system. However, monitoring <br /> requirements for the bioremediation program could increase the cost ;significantly. Therefore, we <br /> recommend installation of an SVE. system at the site. <br /> Based upon the lithology at the site (clay with gravel, clayey gravel), a unit capable of 100 to 200 <br /> scfm should be suitable for vapor extraction. However, due to high carbon dioxide concentrations <br /> in the extracted soil vapor encountered during the pilot test and the resulting high consumption rate <br /> of supplemental fuel, an 1C engine may not be the more cast-efficient option for hydrocarbon <br /> destruction. For that purpose, we recommend the installation of a thermal oxidation SVE unit as the <br /> more cost-effective method. An 18 to 24-month soil remediation period is estimated to remediate the <br /> site. <br /> The SVE system should consist of the extraction unit, existing extraction well VEl and an additional <br /> extraction well to be installed directly west of B2, adjacent to the grocery store. <br /> 7.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> _ environmental consultants practicing in this or similar localities. The findings were based upon <br />