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Fourth Quarter 2003 Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 4 event indicate a slight increase in the concentration of MTBE detected in the groundwater sample collected from MW-9 relative to the previous sampling event conducted in October 2003. The laboratory analytical results for the November 26, 2003, groundwater monitoring event are presented in Table 2, below. A map showing MTBE isoconcentration contours in groundwater is on as Figure 6, attached. TABLE 2: Laboratory Analytical Results for MTBE and Groundwater Elevation Data (November 26, 2003) 1Vlon" inSample Y.D. Monitoring MTBETOC Elevation' Depth to Groundwater Well /L Groundwater Elevation2 MW-2 NS NS 35.97 23.65 12.32 MW-3 3761-MW3-11-26-03 <0.5 36.18 22.44 13.74 MW-4R 3761-MW4R-1 1-26-03 11 35.21 23.07 12.14 MW-6 3761-MW6-11-26-03 NS 36.07 DRY NM MW-7 NS NS 36.42 23.53 12.89 MW-8 NS NS 36.43 NM NM MW-9 3761-MW9-11-26-03 12 35.95 23.72. 12.23 MW-10 3761-MWIO-11-26-03 150 36.09 24.21 11.88 MW-11 3761-MW11-11-26-03 1,000 36.15 23.98 12.17 • EW-1 3761-EW 1-11-26-03 230 36.23 24.11 12.12 'TOC Elevation:Elevations are referenced to NAD83 datum,NGS Benchmark HS 4486. =Groundwater Elevation:Elevations are measured from the top of the well casings and are referenced to the benchmark indicated above. Monitoring wells MW-1,MW-4,and MW-5 were destroyed October 29,2003 Monitoring wells MW-4R,MW-10,and MW-1 1,and extraction well EW-1 were installed October 30,2003 Monitoring wells MW-2 and MW-7 had insufficient water column to purge and sample Unit Conversions: pg/L:parts per billion(ppb) NM =Not Measured All measurements are in feet. Analytical: MTBE=methyl tertiary-butyl ether NS=Not Sampled DECEMBER 31, 2003, QUARTERLY GROUNDWATER MONITORING EVENT On December 31, 2003, a Condor representative was on site to measure water levels and collect groundwater samples from monitoring wells MW-2 through MW-11 and EW-1. The locations of the monitoring wells are shown in Figure 2, attached. Field observations included water 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, sheen, or odors associated with petroleum hydrocarbons were observed in the groundwater inspection samples from the monitoring wells. Field observations are included on the Groundwater Monitoring Field Forms, attached. Groundwater elevations fluctuated relative to the previous monthly monitoring event (November 2043) W= with the average groundwater elevation increasing by 1.70 feet. Groundwater elevation data is presented in Table 4, below, and historic groundwater elevation data is attached. i t i CONDOR