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First Quarter 2004 Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 2 with petroleum hydrocarbons were observed in the groundwater inspection samples from the monitor wells. Field observations are included on the Groundwater Monitoring Field Forms, attached. GROUNDWATER ELEVATIONS AND GRADIENT The average depth to groundwater was approximately 20.33 feet below the well measuring points, a decrease of 1.56 feet since the previous monitoring event (December 2003). Monitor wells MW-9, MW- 11, and EW-1 are screened in a deeper zone than the other monitor wells at the site. Groundwater elevations in these three wells are higher than in nearby wells, indicating that there is currently an upward vertical gradient at the site. Groundwater elevation data are presented in Table 1, below, and historical groundwater elevation data are attached. Table 1: Groundwater Elevation Data kNarch 4,2004 Monitoring Well TOC Elevation[ Screened Depth to Groundwater Interval b s) Groundwater Elevation' MW-2 35.97 15-25 19.99 15.98 MW-3 36.18 15-25 20.93 15.25 MW-4R 35.21 10-25 19.66 15.55 MW-6 36.07 10-25 19.96 16.11 MW-7 36.42 10-25 21.02 15.40 MW-8 36.43 10-25 20.91 15,52 MW-9 35.95 40-50 19.73 16.22 MW-10 36.09 10-25 20.92 15.17 MW-11 36.15 29-39 20.02 16.13 EW-1 36,23 29-39 20.12 16.11 . 'TOC Elevation:Elevations are referenced to NAVD88 datum,NGS Benchmark HS 44W =Groundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark'indicated above. All measurements are in feet. An estimated groundwater gradient of 0.0048 ft/ft towards the northeast was calculated using water level data from monitor wells MW-2, MW-6, and MW-8. Historical groundwater gradients reported for the site have been highly variable (Table 2, on the next page, and Figure 4, attached). 4M La CONDOR