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1,frJ <br /> 27 June 1996 <br /> AGE-NC Project No. 95-0118 <br /> _r Page 13 of 23 <br /> thermal destruction. All are feasible methods of remediating sandy soil contaminated with gasoline. <br /> Off-site disposal generally involves the transportation of the impacted soil to a licensed <br /> 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 the fastest and most effective method for soil remediation. Impacted soil in the vadose and <br /> smear zones extend to a depth in excess of 35 feet bsg. Therefore, soil would have to excavated to <br /> depths greater than 35 feet bsg. Once excavated;the impacted soil is generally stockpiled onsite for <br /> treatment or transportation for disposal. If soil is treated on-site and hydrocarbon concentrations can <br /> be reduced to non-detectable(ND) levels,the soil can be used to backfill the excavation; if the soil <br /> is disposed off-site, backfill must be imported for the excavation. <br /> 7.2.2. FEASIBILITY OF EXCAVATION <br /> Excavation of impacted soil, followed by ex-situ treatment and/or disposal is a very effective method <br /> -- of remediation; non-detect (ND) can usually be achieved by excavation since, theoretically, all <br /> =_ contaminated soil is removed. However, excavation is usually too costly if the volume of impacted <br /> soil is too great or if the impacted soil is present at depths requiring special equipment or extensive <br /> -:� shoring. Both special excavation equipment and shoring would be required at the Elkhorn Country <br /> Club site. <br /> Excavation at the Elkhorn site is not a very feasible considering the depth of impacted soil, space <br /> limitations, current site usage and the cost for disposal and backfill. . <br /> 7.2.3. ESTIMATED COSTS FOR EXCAVATION <br /> At the subject site, impacted soil could not be excavated with standard excavating equipment. If <br /> F disruption of site operations and space Iimitations force off-site disposal,the cost for excavation of <br /> impacted soil could exceed $150 per cubic yard. Soil at the site would have to be excavated to depths <br /> of approximately 40.feet bsg. Based upon the removal of at least 1,200 cubic yards (25 vertical feet <br /> Of soil with a radius of approximately 20 feet) of hydrocarbon-impacted soil,the costs would range <br /> from $120,000 to $250,000. <br /> ,J - - <br /> .r-3 <br />