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20 <br /> Excavation of the soil contaminants and removal of that soil from the site could possibly <br /> result in unconditional closure of the eastern portion of the parcel. Excavation and off-site <br /> disposal, however, will result in generation of a waste. Presently that waste would be <br /> considered hazardous in accordance with the TTLC and STLC levels for lead as set forth in <br /> the California Code of Regulations, Title 22. Supplemental test data, specifically the <br /> deionized WET data, indicate that a variance from the hazardous classification could <br /> possibly be obtained. <br /> Site mitigation alternatives for the western portion of the parcel are unclear due to the <br /> limited data at boring B4. Available data suggest that soil and ground-water contamination <br /> is probably localized, however, the source of contamination has not been identified. Unlike <br /> the eastern portion of the parcel, ground-water contamination is present. As a result, <br /> additional site mitigation alternatives besides those discussed above may be necessary. <br /> Site Characterization <br /> Additional site characterization efforts are particularly needed to define the extent of soil <br /> and ground-water contamination in the vicinity of boring B4. In light of the high correlation <br /> observed between the soil gas results and the subsequent verification sampling results, a <br /> supplemental soil gas survey on the western portion of the parcel is recommended. The <br /> survey would be conducted in a manner similar to the methods discussed in the June 1993 <br /> Work Plan (LSCS). <br /> Following evaluation of the soil gas survey results, a work plan detailing additional soil and <br /> ground-water characterization requirements will be prepared. That work plan is anticipated <br /> to include additional shallow soil borings to a depth of approximately five feet on both <br /> portions of the parcel. Soil samples from these borings would be evaluated for selected <br /> metals and organic chemicals (including TPH as oil and organic constituents by EPA 8080 <br /> and EPA 8270). <br /> 10i UHDORFF 6 SCALMANINI <br /> 11 N S U L T 1 N G ENGINEFRS <br />