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' Corrective Action Plan <br /> Montgomery Ward Auto Service Center, Stockton, CA <br />' ■ <br /> Time of Completion <br /> In terms of time required for completion, excavation and disposal is probably the <br /> method that can achieve closure in the least amount of time due to its nature It is <br />' quite possible that an excavation and off-site disposal method of remediation could <br /> be completed in about four to eight weeks Therefore, time of completion is a <br /> very positive aspect of this method and is a significant advantage of this method <br /> Therefore, the maximum grade of 10 was assigned to this criteria for this remedial <br /> alternative <br />' ■ Cost of Co__Mlletion <br /> The cost of implementation is a major factor in considering any remedial option <br /> Assuming 10,800 cu yds (15,120 tons) of impacted soil (note for conversion <br />' purposes it was assumed that 1 cu yd of soil equals 1 4 tons) and approximately <br /> $68 ton for excavation, transportation, off-site disposal of impacted soil, shoring of <br /> the building, imparting and compacting clean backfill, analytical testing, etc , it <br />' would cost approximately $1,028,990 to complete this work (see Table 14) <br /> Therefore, cost is a major drawback for this alternative and a grade of 1 was <br /> assigned to this criteria for this remedial alternative <br /> ■ <br /> Applicabill!y Applicabilityto Ground Water Remediation <br /> The only manner in which the excavation and off-site disposal method can be <br /> applied for ground water remediation is by pumping out contaminated water <br /> following overexcavation of impacted soils to below ground water levels While <br /> this is theoretically possible, it is probably not practically feasible due to two main <br /> reasons The first is that ground water is currently at depths of about 40 feet bgs <br /> Impacted soil probably exists to depth of 55 ft bgs Therefore, overexcavation <br /> would have to be performed to depths of 55 feet bgs Given the difficulties <br /> associated with this option a grade of 1 was assigned to this criteria for this <br /> remedial alternative <br /> Vapor Extraction <br /> Soil vapor extraction is an accepted means of remediating soils impacted with gasoline and <br /> its constituents In this method, soil vapor is extracted using a vacuum pump and piping <br /> connected to wells screened in the vadose zone The important criteria required to design <br /> an optimum soil vapor extraction system (SVES) are permeability of site soils, type and <br /> initial concentrations of contaminants in soil and soil vapor, radius of influence for a site <br /> extraction well, and typical flow rate for a site extraction well <br /> Ir�1mmation on the above parar.�eters was obtained during the pilot teet performed at the <br /> Montgomery Ward Site (see EAI, 1997A) Information obtained from the pilot study was <br />' used in the following feasibility evaluation <br /> ■ <br /> Probability of Achieving Cleanup Goals <br /> From the results of the pilot test, it appears that vapor extraction will be able to <br /> reduce contaminant levels to the cleanup levels proposed herein (see Section 5 0) <br /> Therefore, a grade of 8 was assigned to this criteria for this remedial alternative <br /> Project No 1232 - 14 - <br /> ISAB WORD 1232CAP <br />