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Quarterly Report - Fourth Quarter 2001 TOP FILLING STATION ' 101 South Wilson Way, Stockton, California ' 10. INTRODUCTION AND SCOPE OF WORK Advanced GeoEnv>ronmental, Inc (AGE) has prepared this quarterly report for 101 South Wilson ' Way (the site), Stockton, California The site setting is illustrated on Figure 1 Site structures and monitoring well locations are depicted on Figure 2 ' The objective of the work was to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient on the site This report has been prepared In accordance with guidelines issued by the California Regional Water Quality Control Board- Central Valley Region(RWQCB) for investigation of underground storage tank(UST) sites A summary of previous investigations at the site was Included in the Work Plan Addendum -July ' 1999, dated 08 July 1999, prepared by AGE Ground water monitoring data acquired to date is included in the tables of this report ' 2.0. QUARTERLY GROUNDWATER MONITORING AND SAMPLING PROCEDURES '• On 10 and 11 December 2001, ground water monitoring and sampling were performed at the site on wells MW-1, MW-2, MW-3, MW-4, MW-5, MW-6 (A, B, C, D and E), MW-7 (B, C, D and E), VW-1B, VW-1C, VW-2A and VW-3A As-built monitoring well construction details are ' summarized In Table 1 Ground water monitoring procedures for the site were outlined In Work Plan Addendum, dated 08 November 1995, approved by the San Joaquin County Environmental Health Department (SJC-EHD)by letter dated 27 November 1995 ' 2 1 WELL MONITORING AND EVACUATION Depth to ground water was measured in each well from the tops of the well casings to the nearest ' 0 01-foot utilizing a Solmst water level indicator Ground water elevation in each well at the site was calculated by subtracting the measured depth to ground water from the surveyed casing elevations (Table 2) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) 1 After water levels were measured, approximately 1 to 20 gallons of ground water (a minimum of three casing-water volumes per well) were evacuated (purged) from wells MW-1, MW-2, MW-3, ' MW-4, MW-5, VW-1B, VW-1C, VW-2A and VW-3A utilizing either a submersible pump or a disposable polyethylene bailer Temperature, pH and conductivity were measured for stabilization at regular purge-volume intervals from each well using a Hydac water analyzer Field data and logs ' are in Appendix A Purged ground water was containerized in 55-gallon drums and was stored on- site In an area lacking general public access Advanced GeoEnvironmental,Inc 1