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�r I Quarterly Report - October 1999 ' TOP FILLING STATION 101 South Wilson Way Stockton, California I 1 0. INTRODUCTION Advanced GeoEnvironmental, Inc (AGE) has prepared this Quarterly Report for 101 South Wilson Way, 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 is prepared in accordance with guidelines established by the San Joaquin County Public Health Services - Environmental Health Division (PHS-EHD) and by the Central Valley Regional Water Quality Control Board (CVRWQCB) for investigation of underground storage tank(LIST) sites A summary of previous investigations at the site was included in the Quarterly Report - October 1996, dated 22 November 1996, prepared by AGE 2 0 QUARTERLY MONITORING AND SAMPLING PROCEDURES On 13 October 1999, ground water monitoring and sampling was performed at wells MW-1 through IMW-5, VW-IC, VW-2A and VW-3A Ground water monitoring procedures for the site were outlined in Work Plan Addel7dum, dated 08 November I995 and approved by the PHS-EHD by letter dated 27 November 1995 I21 MONITORING WELL PURGE PROCEDURES Depths to ground water were measured from the top of each well casing at the site to the nearest 0 01 I foot utilizing a Solinst water level meter Ground water elevations in each well at the site were calculated by subtracting the measured depth to ground water from surveyed casing elevations (Table 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) IAfter water levels were measured, approximately 16 to 20 gallons of ground water (a minnnum of three well-volumes per well)were removed from wells MW-1 through MW-5, VW-1C, VW-2A and VW-3A utilizing a submersible Grundfos Redi-flow pump, ground water pumping was initiated at the top of the water column and the pump was slowly lowered to total depth to purge ground water within the entire well casing Temperature, pH and conductivity were measured for stabilization at Iregular 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 GeoEn-.iron mental,Inc I