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,l A Fourth Quarter 2004 Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 2 . level measurement, appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples), and collection of water quality field parameters. No floating product or sheen was observed in the groundwater inspection samples from the monitoring wells. A moderate gasoline odor was observed in the groundwater purged from monitoring well MW-7. Field observations are included on the Groundwater Monitoring Field Forms, attached. GROUNDWATER ELEVATIONS AND GRADIENT The average depth to groundwater was approximately 21.17 feet below the well measuring points, a decrease of 3.28 feet since the previous monitoring event (September 2004). Groundwater elevation data are presented in Table 1, below, and historical groundwater elevation data are attached. Table 1. Groundwater Elevation Data (December 29, 2004) Monitoring Well TOC Elevation' Screened Depth to Groundwater Interval (b s) Groundwater Elevation" MW-2 35.97 15-25 20.84 15.13 MW-3 36.18 15-25 21.59 14.59 MW-4R 35.21 10-25 20.35 14.86 MW-6 36.07 10-25 20.94 15.13 MW-7 36.42 10-25 21.71 I4.71 MW-8 36.43 10-25 21.7.1 14.72 MW-9 35.95 40-50 20.79 15.16 MW-10 36.09 10-25 21.58 14.51 MW-11 36.15 29-39 21.03 15.12 EW-1 36.23 29-39 21.15 15.08 FTOC Elevation:Elevations are referenced to NAVD88 datum,NCS Benchmark HS 4486. =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 0.0036 ft/ft towards the north was calculated using water level data from monitoring wells MW-2, MW-6, and MW-8 (Figure 3, attached). Historical groundwater gradients reported for the site have been highly variable(Table 2, on the next page, and Figure 4, attached). I ,1 A CONDOR