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Former Discovery Chevrolet lune 5, 1998 <br /> Tracy, California Corrective Action Plan <br /> ' immediate disposal at a selected landfill or aboveground treatment of the excavated soil <br /> would be utilized after excavation. The effectiveness of the combination of these <br /> remediation procedures would then be evaluated by short-term post-remedial groundwater <br /> monitoring at the site. The preliminary total cost for these soil and groundwater remediation <br /> alternatives is estimated to range between approximately $38,000 to $50,000. <br /> 6.0 PROPOSED CORRECTIVE ACTION OPTIONS <br /> 6.1 Recommended Corrective Action for Soil and Groundwater <br /> In their letter dated May 13, 1998, the SJC PHS/EHD has stated that excavation of <br /> hydrocarbon-impacted soil has proven to be a viable remedial alternative in the Tracy area. <br /> Based upon the fine-grained soils present beneath the site, the most feasible method for soil <br /> and groundwater remediation at the site would be excavation and aboveground onsite <br /> :} treatment of the hydrocarbon-impacted soils, along with removal and disposal of <br /> hydrocarbon-impacted groundwater from the excavation prior to backfilling, and <br /> groundwater monitoring for a short period of time to evaluate the effectiveness of the <br /> remedial work. It is Horizon's opinion that re-excavation of the former UST pit area to a <br /> depth of approximately 10 feet bsg, as shown on Figure 4, would likely be successful in <br /> removing the majority of remaining gasoline hydrocarbons from the soil beneath the site, <br /> and as such, no additional soil remediation should be necessary for the site. <br /> Declining trends observed in the laboratory analytical results of the quarterly groundwater <br /> monitoring and bioparameters previously monitored at the site indicate that intrinsic <br /> biodegradation is an active method of ongoing passive remediation beneath the site. With <br /> re-excavation of the former UST pit area, and extraction and treatment of groundwater, <br /> intrinsic bioremediation will continue to decrease the levels of gasoline hydrocarbons <br /> remaining in the subsurface soils and groundwater beneath the site. <br /> 3001-21.cap 16 HORIZON ENVIRONMENTAL INC. <br />