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I Quarterly Report - First Quarter 2001 ' TOP FILLING STATION 101 South Wilson Way, Stockton, California ' 1.0. INTRODUCTION AND SCOPE OF WORK ' Advanced GeoEnvironmental,Inc (AGE)has prepared this quarterly report for the first quarter 2001 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 charactenze ground water flow direction and gradient on the site This report is prepared in accordance with guidelines established 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 2.0. QUARTERLY GROUNDWATER MONITORING AND SAMPLING PROCEDURES • On 07 February 2001, ground water monitoring and sampling were performed at the site on wells MW-1, MW-2, MW-3, MW-4, MW-5, VW-113, VW-1C, VW-2A, VW-213, VW-3A and VW-3B (wells MW-I through VW-3) Ground water monitoring procedures for the site were outlined in ' Work Plan Addendum, dated 08 November 1995 and approved by the San Joaquin County Public Health Services - Environmental Health Division (PHS-EHD) by letter dated 27 November 1995 I2 1 MONITORING WELL PURGE PROCEDURES Depth to ground water was measured in each well from the tops of the well casings to the nearest 0 01-foot utilizing a Solinst 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 1) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) After water levels were measured, approximately 1 to 20 gallons of ground water (a minimum of three casing-water volumes per well)were removed from each well utilizing a submersible pump or by hand-bailing with a disposable bailer Approximately 12 gallons of ground water were removed from well MW-4 before being pumped"dry'Temperature,pH and conductivity were measured for stabilization at regular purge-volume intervals from each well using an Oakton water analyzer Field data and logs are in Appendix A Purged ground water was contamenzed in 55-gallon drums and was stored on-site in an area lacking general public access I IAdvanced GeoEnvironmental,Inc