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r r <br /> t <br /> 16 August 2001 <br /> AGE-NC Project No 97-0312 ` <br /> Page 8 of 20 - <br /> x <br /> 7 0. 'SOIL REMEDIATION ALTERNATIVES <br /> I <br /> Four methods for remediation of fuel components-Impacted soil for the site were evaluated with <br />' - consideration of site-specific factors The methods considered Included ex-situ treatment, in-situ <br /> bioremediation and natural attenuation In addition, a "no further action" option was assessed <br /> 71 EX-SITU TREATMENT OF D"Ar CTED 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 thennal destruction All are feasible methods for above-ground remediation of soil <br />' contaminated with gasoline and diesel fuel Off-site disposal generally involves the transportation <br /> ofthe impacted soil to a licensed treatmenttdisposal facility Excavation would necessitate disruption <br /> of normal site activities during excavation, backfilling and repaving <br /> 711 Excavation <br /> All of the mentioned methods of ex-situ treatment require excavation of the Impacted soil, which <br /> is generally an effective method for soil remediation Once excavated,the impacted soil is generally <br /> stockpiled on-site for treatment or transported off-site for disposal If soil is treated on-site and the <br /> hydrocarbon concentrations can be reduced to concentrations set by the lead_agency or to non- <br /> detectable concentrations, the soil may be used to backfill the excavation If the hydrocarbon- <br /> impacted soil is disposed of off-site, material must be Imported to backfill the excavation <br /> 7 1 2 , Feasibility Of Excavation <br /> Excavation of impacted soil to depths greater than 25 feet bsg would require specialized excavating <br /> I equipment and excavating techniques Excavation of hydrocarbon-impacted soil to depth's greater <br /> than 55 feet bsg (estimated depth to ground water) would require a ground water pumping system <br /> I to facilitate the -dewatering of the excavation Site excavation activities would also require the <br /> destruction of on-site wells,which would necessitate monitoring well replacement at another time <br /> Other potential disadvantages of site excavation Include significantly higher costs for deeper <br /> excavation and backfilling and continued liability for off-site disposal Future liability for off-site <br /> disposal could be reduced through indemnification offered by some soil recycling facilities <br /> • <br /> Advanced GcoEnvironmental,Inc <br />