Laserfiche WebLink
Former Discovery Chevrolet June 5, 1998 <br /> Tracy,California Corrective Action Plan <br /> 5.2.1.1 Excavation and Disposal <br /> As briefly described in the PAR, this alternative involves the removal and disposal of soils <br /> containing petroleum hydrocarbons above acceptable concentrations. Excavation would <br /> involve removal, disposal, and replacement of site surface material consisting of asphalt and <br /> concrete, as well as unimpacted overburden soils. Excavated hydrocarbon-impacted soils <br /> would be manifested and transported by a licensed contractor to a Class II or III landfill. <br /> Clean imported material would then be used to backfill the excavation. If possible, <br /> overburden soil that has not been impacted would also be utilized as backfill. <br /> To date, the SJC PHSIEHD has not formally established a Target Cleanup Level (TCL) for <br /> the site. However, in prior verbal discussions the SJC PHS/EHD has indicated that removal <br /> of hydrocarbon-impacted soil in the immediate area of the former excavation should suffice <br /> in reducing future impacts to the shallow groundwater beneath the site. A summary of <br /> analytical results of soil samples for benzene were used to construct a soil isoconcentration <br /> r: map of benzene at depths of 8 to 10 feet bsg (Figure No. 3). These benzene analytical <br /> results were previously presented as Figure No. 7 in the PAR. <br /> As presented in the Mass Balance of Petroleum Constituents in Soil section of the PAR, the <br /> 1,000 ppm TPHg isoconcentration contour generally reflects the area of subsurface soil <br /> impacted by fuel hydrocarbons from the former product line, while the 100 ppm TPHg <br /> isoconcentration contour generally reflects the area of subsurface soil impacted by the spread <br /> of dissolved fuel hydrocarbons along the surface of the groundwater. Mass balance <br /> calculations indicate that approximately 300 cubic yards of impacted soil exist at the site <br /> within the 100 ppm TPHg isoconcentration contour, down to the depth of groundwater at �1fg <br /> approximately 10 feet. In order to remove the approximately 300 cubic yards of <br /> s <br /> hydrocarbon-impacted soil, approximately 600 additional cubic yards of overburden soil i <br /> would first have to be excavated at the site. The overburden soil would be stockpiled <br /> separately for later utilization as backfill materials. The total excavation volume therefore <br /> would be estimated to be approximately 900 cubic yards. bd c <br /> 3001-21.cap 10 HORIZON ENVIRONMENTAL INC. `'\ <br />