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Stockton City Taxi Company • 2085 E. Fremont Street Stockton, California Quarterly Groundwater Sampling Report October, 2003 1 Narrative On October 10 2003 GeoAnal icaI yt Laboratories,bo atones, Inc., conducted field measurements, well pumping and groundwater sampling on four (4) groundwater monitoring wells r located at this site (Figures 1 and 2). Groundwater elevations. were taken from four (4) wells prior to pumping (Table I & Appendix B). Monitoring wells MW-1 through MW-4 were evacuated by means of a steam-cleaned, stainless steel bladder type pump. During the three (3) volume pump down of each well, samples were collected to measure field pH, electrical conductivity and temperature (Table 3 & Appendix B). Once stability was achieved, a minimum of three (3) well volumes were removed and samples were collected with a disposable bailer. The samples were then labeled and placed in an ice chest cooled with Ice®. The samples were then logged on a Chain of Custody (Appendix A) and transported to the State-certified laboratory, GeoAnalytical Laboratory Inc., in Modesto, California. The analysis requested for the four (4) water samples was EPA method 8260B for BTX&E (Benzene, Toluene, Xylene, and Ethyl-Benzene), MTBE, ethanol, tert-Butanol, DIPE, ETBE, TAME, EDB, and 1,2-DCA, and EPA method GCFID (5030/Luft) for gasoline. The analytes and concentrations detected are listed in Table 2 of this report. Figure 3 depicts the well collar survey elevations. The survey was conducted following the guidelines set forth in the State GeoTracker Program. Groundwater Gradient The water level measurements from three (3) monitoring wells were used to construct a groundwater gradient map (Figure 4). MW-4 was not used in the calculation of the 1 gradient because it is a deep well with a ten foot discrete screen. This quarter, the groundwater gradient trend is South 84° East with a downward slope of 0.0024 ft/ft.