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. Closure Report - Chevron Station#9-1848 <br /> January 18, 1999 <br /> ppm) and benzene (0 010 ppm), and the soil sample from well. boring C-2 at 16 feet bgs <br /> contained TPHg (13 ppm) and benzene (0 11 ppm) also These borings appear to define the <br /> lateral and vertical extent of petroleum hydrocarbon impacted soil beneath the site <br /> Furthermore, soil samples from the four off-site soil borings did not contain detectable <br /> petroleum hydrocarbons, thus delineating the soil east, northeast, north, and west of the site <br /> Groundwater impacted by petroleum hydrocarbons appears to be confined to wells C-1 and <br /> C-2 Moreover, it appears the groundwater plume has not migrated off-site and is stable as <br /> evidenced by the grab groundwater samples collected from borings B-1 through B-4 <br /> Based on these data, additional investigation or remediation of soil or groundwater is not <br /> warranted, and the site should be closed In support of the closure request, we summarize the <br /> information requested in Appendix B of the CRWQCB Request For Closure guidelines This <br /> information is presented point by point as outlined in the document <br /> I Background history of the case <br /> The case history is summarized above <br /> . H Investigative methods <br /> Based on our review of available documentation, work performed at the site to date <br /> appears to have followed the appropriate San Joaquin County Department of Public <br /> Health Services (SJCDPHS) and RWQCB guidelines for the investigation and <br /> remediation of hydrocarbon-impacted sites, and the accepted methods and practices in <br /> general use at the time the woi k was performed <br /> III Extent of soil and groundwatet pollution <br /> The lateral and vertical extent of hydrocarbon impact has been defined. Impacted soil <br /> from the former gasoline UST pit, associated product lines, waste oil UST, hydraulic <br /> lifts and fluid tank, grease traps, and oil water separator had been excavated until only <br /> low levels of petroleum hydrocarbon concentrations were Ieft in place Approximately <br /> 960 cubic yards of soil was transported to Forward Landfill in Stockton, California <br /> Approximately 30 cubic yards of soil containing waste oil were transported to Browning <br /> Ferris Industries in Livermore, California Approximately 450 cubic yards of soil were <br /> used to backfill the former UST excavation <br /> Impacted groundwater appears confined to on-site wells C-1 and C-2 Free-phase <br /> hydrocarbons have never been measured or observed in the any of the three wells at this <br /> • 34639202-0 4 <br /> ifk .i <br /> - M <br />