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Closure Report - Chevron Station#9-1848 <br /> January 18, 1999 <br /> site The extent of the dissolved hydrocarbon plume has been defined and appears <br /> stable Concentrations of dissolved petroleum hydrocarbons were not detected in the <br /> off-site soil boi ings <br /> V Beneficial uses <br /> As defined in the RWQCB's Basin Plan (1990), the existing and potential future <br /> beneficial uses of the groundwatet beneath the San Joaquin Rivei Basin include <br /> municipal and domestic supply, agi tcuitural supply, and industrial supply <br /> A review of available records for wells within 0 5-mile of the site was conducted by <br /> G-R on January 28, 1998 At this time, DWR files did not appear to contain any well <br /> records later than 1989 Wells within a 0 5 mile radius of the site are listed in <br /> Appendix D, Table 1 <br /> Six sites with wells were identified within the 0 5-mile radius Four of the sites listed <br /> have domestic supply wells and one has a municipal supply well The nearest domestic <br /> well is located appioximately 0 1-mile northeast of the subject site The nearest <br /> • municipal well is also located approximately 0 5-mile northeast of the site There do <br /> not appear to be any neaiby existing of potential sensitive groundwater receptors which <br /> might be impacted by hydrocarbons from the Chevron site <br /> VI Remediation Activities <br /> Remedial activities at the site were limited to source removal Gasoline USTS and <br /> associated product lines have been replaced The waste oil UST, hydi aulic hoists, <br /> hydraulic fluid tanks, grease tiaps, and oil-water separatoi have been iemoved Soil at <br /> the base of the former gasoline UST pit and associated product lines contains TPHg <br /> concentrations less than 450 ppm at 16 feet bgs, and 2,100 ppm at 4 5 feet bgs, <br /> respectively Soil at the base of the present UST pit contained less than 190 ppm of <br /> TPHg at the time the pit was dug Soil beneath the former hydraulic hoists contains less <br /> than 15 ppm Total Peti oleum hydrocarbons as oil (TPHo) Soil beneath the former <br /> waste-oil UST contains less than 2 4 ppm TPIIg <br /> VII Remediation Effectiveness <br /> Based on the lack of detectable petroleum hydrocarbons in the off-site soil borings, the <br /> variable flow of groundwater beneath the site, and the lack of other potentially sensitive <br /> receptors in the immediate vicinity of the site, the current and potential future beneficial <br /> • 3A6392 02 rJ 5 <br /> f <br />