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I wells within the area of soil contamination A vacuum pump would be used to apply a negative pressure head to draw volatile hydrocarbon constituents to the vapor wells These wells would ' be plumbed to a carbon filter unit to adsorb the contaminants or some other off gas treatment technology prior to being emitted to the atmosphere Tight soil types such as the clays and silts/silty sands at this site are not considered ideal candidates for vapor extraction nor are partially saturated (capillary) soils. The success of remediation using this technique would be Iuncertain ' 662 Groundwater Remediation Alternatives Laboratory analyses of discrete groundwater samples collected from soil bonngs SB2, SB3, SB5, SB7, and SB9 indicate that groundwater has been impacted by residual petroleum hydrocarbons associated with the former gasoline storage tank and dispenser island The absence of contaminants in existing wells T1, T2, and T3 suggests that the lateral extent of groundwater contamination may be somewhat localized The entire extent of groundwater impaction has not ibeen completely defined ' The full extent of groundwater impaction should be defined prior to developing remedial action ' plan for groundwater However, it may be feasible to significantly reduce the volume of impacted groundwater by pumping water that collects in the excavation pit during soil ' excavation ' 7.0 RECOMMENDED SOIL REMEDIATION WORKPLAN To prevent the remaining impacted soil from acting as potential source of continued groundwater ' degradation RESNA recommends the following scope of work 77.1 Excavation Suspected hydrocarbon impacted soils should be excavated by a licensed California contractor, ' employing a backhoe tractor or tracked excavator to perform the excavation It is estimated that approximately 1,600 cubic yards of soil would require excavating, 800 to 1,125 cubic yards of 1500871R-053194 FNL 8