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1 02 June 1997 ' AGE-NC Project No 95-0105 Page 9 of 11 ' 5.0. WELL SURVEY A well survey was conducted to gather information regarding the location and use of municipal and domestic wells within 2,000 feet of the site The PHS-EHD and the State of California Water Resources Control Board records were reviewed No active, domestic ground water wells were discovered within the search range A ground water monitoring well is located approximately 90 feet northwest of the site, at the City of Tracy-Fire Station No detectable concentrations of petroleum hydrocarbons were present in a ground water sample collected from the well in the first quarter of 1996 ' 6 0. SUMMARY/CONCLUSIONS AND RECOMMENDATIONS Based on data collected from the site, AGE has made the following findings and conclusions • Approximately 200 cubic yards of hydrocarbon-impacted soil was iemoved from the site in April and June 1995 • Approximately 590 cubic yards of hydrocarbon-impacted soil remains in the unsaturated zone and the capillary fringe zone off-site under Grant Line Road • On-site hydrocarbon-impacted soil remains above and in the saturated zone in the area south of the former dispenser and under the building at the site An estimated 160 cubic yards remain on the site under the canopy and structure The lateral extent of the hydrocarbon impacted soil is depicted in Figure 6 -Hydrocarbon Impacted Soil • An estimated 720 gallons of gasoline remain in the soil both on and off the site from the ' unauthorized release of hydrocarbons An estimated 260 gallons impact the off-site soil and an estimated 660 gallons impact the on-site soil ' Between the installation and initial sampling of hydrocarbon-impacted wells and the present time, the concentrations of dissolved TPH as gasoline and BTE&X have remained stable at the site Concentrations of dissolved TPH-d have decreased over this time period ' Petroleum hydrocarbons have not been detected in a well located approximately 90 feet northwest of well MW-4 on the City of Tracy Fire Department Property, providing a ' northwest limit to the dissolved hydrocarbon-impacted ground water plume Monitoring well MW-5, located approximately 75 feet east of well MW-4, represents the eastern limit of the dissolved hydrocarbon plume,while well MW-6, located approximately 55 feet north of well MW-4, represents the northern limit of the hydrocarbon-impacted ground water • The PHS-EHD declined requiring a monitoring well to delineate the western margin of the dissolved hydrocarbon plume This is not thought to be a serious problem as the western