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Quarterly Report June 1999 <br /> TOP FILLING STATION <br /> 101 South Wilson Way <br /> Stockton, California <br /> I.O. INTRODUCTION <br /> Advanced GeoEnvironmental, Inc (AGE)has prepared this Quarterly Report for 101 South Wilson <br /> Way, Stockton, California The site setting is illustrated on Figure 1 Site structures and monitoring <br /> well locations are depicted on Figure 2 <br /> The objective of the work was to monitor dissolved petroleum hydrocarbon concentrations in ground <br /> water and to characterize ground water flow direction and gradient on the site This report Is <br /> prepared in accordance with guidelines established by the San Joaquin County Public Health <br /> Services - Environmental Health Division (PHS-EHD) and by the Central Valley Regional Water <br /> Quality Control Board (CVRWQCB) for investigation of underground storage tank (UST) sites A <br /> summary of previous investigations at the site was included in the Quarterly Report- October 1996, <br /> dated 22 November 1996, prepared by AGE <br /> 2 O. QUARTERLY MONITORING AND SAMPLING PROCEDURES <br /> On 14 June 1999, ground water monitoring and sampling was performed at wells MW-1, MW-2, <br /> MW-3,MW-5,V W-I C,V W-2A and V W-3A Groundwater monitoring procedures for the site were <br /> outlined in Work Plan Addendum, dated 08 November 1995 and approved by the PHS-EHD by <br /> letter dated 27 November 1995 <br /> 2 1 MONITORING WELL PURGE PROCEDURES <br /> Depths to ground water were measured from the top of each well casing at the site to the nearest 0 01 <br /> foot utilizing a Solinst water level meter Ground water elevations in each well at the site were <br /> calculated by subtracting the measured depth to ground water from surveyed casing elevations <br /> (Table 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) <br /> After water levels were measured, approximately twenty gallons of ground water (a minimum of <br /> three well-volumes per well)were removed from wells MW-1,MW-2,MW-3,MW-5,VW-1C,VW- <br /> 2A and VW-3A utilizing a submersible Grundfos Redl-flow pump, ground water pumping was <br /> initiated at the top of the water column and the pump was slowly lowered to total depth to purge <br /> ground water within the entire well casing Temperature, pH and conductivity were measured for <br /> stabilization at regular purge-volume intervals from each well using an ICM Model 52200 water <br /> analyzer Field data and logs are in Appendix A Purged ground water was containerized In 55-gallon <br /> drums and was stored on-site in an area lacking general public access <br /> Ads anced GeoEmironmental,Inc <br />