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• Third Quarter Groundwater Monitoring Report September 2003 Boyett Petroleum,419 S.Main,Manteca,CA Page 5 • SEPTEMBER 30 2003 UARTERLY GROUNDWATER MONITORING EVENT A summary of the results of the third quarter 2003 groundwater monitoring event is provided in Table 3, below. Table 3: Summary of September 2003 Quarterly Groundwater Monitoring Results Field Activity Number of groundwater wells 9 Number of groundwater wells sampled 2* Number of groundwater wells 9 Date(s)monitored and sampled 9/30/2003 monitored Site Hydrology Average depth to groundwater below monitoring well measuring 23.21 feet Average increase (+)/decrease(—)in 10.59 feet oints depths to groundwater since last sampling (Deeper) Approximate flow direction and Indeterminate due to low groundwater elevation groundwater ffadient Groundwater Contamination Monitor wells containing free 0 Monitor wells with detected petroleum 0 -product hydrocarbon odors Maximum concentrations detected in the Nature of contamination: MTBE monitor wells: MTBE(µg/L) 35 * Monitor wells MW-2,MW-3,MW-4,MW-5,MW-6,MW-7,and MW-8 were not sampled because the wells were dry or there was not enough water in the well to collect a sample. . FIELD OBSERVATIONS On September 30, 2003, a Condor representative was on site to measure water levels and collect groundwater samples from monitor wells MW-1 through MW-9. The locations of the monitor wells are shown in Figure 2, attached. Monitor wells MW-2, MW-4, and MW-5 were dry, and monitor wells MW- 3, MW-6, MW-7, and MW-8 purged dry; as a result, groundwater samples were collected only from monitor wells MW-1 and MW-9. Field observations included water level measurement (Table 4, on the following page), appearance of samples (color, clarity, and presence of petroleum product sheen or phase in samples), and collection of water quality field parameters. Field observations are included on the Groundwater Monitoring Field Forms, attached. No floating product, sheen, or odors associated with petroleum hydrocarbons were observed in the groundwater inspection samples purged from the monitor wells MW-1, MW-3, MW-7, and MW-9 during the September 30, 2003 groundwater monitoring event. Clarity was good in the field inspection sample collected from MW-1. The initial groundwater purged from MW-9 contained sandy sediment and turned clear with additional volumes purged. GROUNDWATER ELEVATIONS AND GRADIENT Groundwater elevations fluctuated relative to the previous quarterly monitoring event (,Tune 2003). The average groundwater elevation decreased with respect to the previous quarterly monitoring event by 2.42 feet and with respect to the last monthly monitoring event in August 2003 by 0.59 feet. Groundwater elevation data is presented in Table 4, on the next page, and historic groundwater elevation data is attached. • �� CONDOR