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I Quarterly Report - First Quarter 2003 • PACIFIC CAR WASH ' 4405 Pacific Avenue, Stockton, California ' 1.0. INTRODUCTION ' Advanced GeoEnvironmental,Inc (AGE)has prepared this quarterly report for 4405 Pacific Avenue (the site), Stockton, California The scope of work included conducting a quarterly ground water monitoring event and preparation of this report The objectives were to characterize, assess and monitor concentrations ofpetroleum hydrocarbons in groundwater and to characterize ground water flow direction and gradient at the site The site setting Is Illustrated in Figure 1 Site structures and monitoring well locations are depicted in Figure 2 ' This report is 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 ofprevious investigations at the site was included in the AGE-prepared Preliminary Site Investigation and Evaluation Report-January 1997, dated 15 January 1997 i2.0. PROCEDURES i On 25 February 2003, a ground water monitoring event was performed at the site on wells MW-I through MW-12, monitoring well construction details are summarized in Table 1 Ground water monitoring procedures for the site were outlined in the AGE-prepared Work Plan Addendum -June 1998, dated 10 June 1998, and approved by the SJCEHD by letter dated 24 June 1998 I At the request of the SJCEHD, ground water monitoring activities at the Pacific Car Wash site were coordinated to occur concurrently with the ground water monitoring activities at the Pacific Mini Mart site (4511 Pacific Avenue), the Pacific Mini Mart tabulated ground water elevation and ' analytical results are Included in Appendix A 2 1 GROUND WATER MONITORING PROCEDURES On 25 February 2003, depth to ground water was measured in each well from the top of the well casing to the nearest 0 01-foot utilizing a Solinst water level meter The ground water elevation in each weii was caicuiated by suntractmg the measured depth to grounci water from the surveyea casing elevation(Table 2) Ground water elevations were plotted and contoured on a scaled site map (Figure 3) After water levels were measured, approximately 4%2 to 11% gallons of ground water(a minimum of three casing-water volumes per well)were evacuated(purged)from wells MW-1 through MW-12 utilizing disposable bailers, approximately 6 gallons of water were purged from MW-1 before the well was purged"dry" Temperature,pH and conductivity were measured for stabilization at regular Advanced GcoEnvi ron mental,Inc