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Quarterly Report - April 1999 • CALIFORNIA FUELS CARDLOCK STATION 2402 Pacific Avenue, Stockton, California ' 1.0. INTRODUCTION Advanced GeoEnvironmental, Inc (AGE) has prepared this Quarterly Report for 2402 Pacific Avenue, 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 (UST) sites A summary of previous investigations at the site was included in the Carr ective Action Plan- May 1998, dated 05 May 1998 and prepared by AGE 2.0. Q UARTERLY MONITORING AND SAMPLING PROCEDURES On 28 April 1999, ground water monitoring and sampling was performed at wells MW-I through MW-4, MW-6 through MW-10, MW-12, VW-1, AWAB and AW-213 Ground water monitoring I procedures for the site were outlined in Work Plan Addendum - June 1998, dated 08 June 1998 prepared by AGE and approved by the PHS-EHD by letter dated 30 June 1998 21 MONITORING WELL PURGE PROCEDURES Depths to ground water were measured in each well from the tops of the well casings at the site to the nearest 0 01 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) Q fre,- 11 Tater level.- �vere lL e-asured, approx.M..-tely V o JV �111AolAs of gro:\rid water (a m:ri:nu.:l Vf 11 LVL Y.K VL three well-volumes per well) were removed from wells MW-1 through MW-4, MW-6 through MW- 10, MW-12, VW-1, AW-1B and AW-213 utilizing a two-stage submersible pump (purge pump), the purge pump was initially set at the top of the water column and then slowly lowered to the total depth of each well Approximately 2 gallons of ground water were removed from well MW-11 before being pumped "dry" Temperature, pH and conductivity were measured for stabilization at • regular purge-volume intervals from each well using an ICM Model 52200 water analyzer Field data 1 and logs are included with Appendix A Purged ground water was containerized in 55-gallon drums