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Working To Restore Nature <br /> ppm) and xylenes (0.029 ppm). Analytical results are summarized on Table 1. Laboratory data <br /> sheets are included in Attachment 3. <br /> Based on the results of sample SBIS-NCB-30', on January 13, 1994 excavation activities were <br /> resumed. Soils from the central portion of the excavation were removed to a depth of <br /> approximately 32 feet below ground surface. One additional confirmation soil sample(SBIS-CB- <br /> 32') was subsequently collected, transported and analyzed under the methods described above. <br /> No field evidence of residual hydrocarbon contaminated soil was observed during the secondary <br /> excavation activities. Laboratory analyses of this sample did not detect any petroleum <br /> hydrocarbon analytes. <br /> Subsequent to excavation activities, the pit was backfilled with imported self compacting fill <br /> material in accordance with local agency requirements. All potentially impacted soil stockpiled <br /> on site was transported to Forward Landfill in Manteca, California for disposal. The non- <br /> hazardous waste manifests are included in Attachment 4. <br /> Analytical Results - Summary <br /> No hydrocarbon analytes were detected in any of the final confirmation samples from the <br /> excavation pit. Analytical results are summarized in Table 1. Laboratory data sheets and chain- <br /> of-custody documentation are presented in Attachment 3. <br /> CONCLUSIONS/RECOMMENDATIONS <br /> Soils <br /> Field observations and analytical data indicate that vertical migration of contamination had not <br /> occurred beyond 30 feet below surface grade and that lateral migration was not extensive. <br /> Analytical data indicated that the main area of concern was the soil in the vicinity of the former <br /> central unleaded gasoline fuel tank pit. This portion of the pit was excavated to a depth of 32 <br /> feet below grade. Analytical results of excavation confirmation samples indicate that all <br /> impacted soil has been removed. No further action is recommended. <br /> Groundwater <br /> Groundwater was not encountered during site activities. Based upon regional groundwater data, <br /> depth to groundwater is estimated to be approximately 45 feet below ground surface and flows <br /> in a eastern direction (San Joaquin County Flood Control and Water Conservation District, <br /> Spring 1993). Historically, groundwater may have been as high as 35 feet below ground surface <br /> (San Joaquin County Flood Control and Water Conservation District, Spring 1986). <br /> 1500531REP0RTSIEXCV-294.FNL 3 <br />