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• Request For Closure,Former Unocal Station#0123,Tracy,CA April 19,2001 4) Stockpiled soil remaining on-site or off-site disposal(quantity). No stockpiled soil remains at the site In 1965, the service station was demolished and the southern most UST cluster was removed, but no information regarding the removal and disposal of soil during these activities is available iii Unocal's files Information regarding soil generated by PEG in 1995 during the drilling of 12 soil and well bonngs was also not available in Unocal's files At that time,the northern most UST cluster was left in place because of its location beneath the sidewalk In November 1996, two of the three USTs in the northern cluster were removed and groundwater monitoring well U-4 was installed, and approximately 75 cubic yards of soil was generated This soil was removed from the site in December 1996 and transported to Forward Landfill in Manteca, California, for disposal In October 1998, during the drilling of three soil and well borings, approximately 5 cubic yards of soil was generated and stockpiled on site Following analysis of a stockpile sample and approval by Forward Landfill for disposal, Manley and Sons Trucking of Sacramento, California,went to the site to retrieve the soil, but the soil was gone Those responsible for removing the soil or its final destination were never determined In November 2000, approximately 0 7 cubic yards of soil was generated during the drilling of 2 off-site wells The soil-vas removed from the site in December 2000 and transported to Forward Landfill for disposal 5) Monitoring wells remaining on-site,fate. Wells U-1 through U-8 remain at the site Copies of boring logs for the wells are in Appendix D 6) Tabulated results of all groundwater elevations and depths to water. Groundwater monitoring data are in Appendix E 'n Tabulated results of all sampling and analyses. Soil sample analytical data are in Appendix F Groundwater sample analytical data are in Appendix E 8) Concentration contours of contaminants found and those remaining in soil and groundwater,both on-site and off-site. TPHg isoconcentration map and cross sections based on soil samples collected in May 1995 are shown on Figures 6 through 9 in Appendix C TPHg range hydrocarbons and benzene isoconcentration maps based on concentrations in groundwater detected in a recent sampling event on December,6, 2000 are shown on Figures 3 and 4 9) Zone of influence calculated and assumptions used for subsurface remediation system and the zone of capture attained for the sod and groundwater remediation system. Not applicable for this site 240073 06 4