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' Fourth Quarter,2002 Quarterly Groundwater Monitoring Report Boyett Petroleum,419 S.Main,Manteca,CA Page 2 Table I Summary of December 2002 Quarterly Groundwater Monitoring Results ' Field Activity Number of groundwater wells 9 Number of groundwater wells sam 1ed 7* Number of groundwater wells 9 Date(s) monitored and sampled 12/27/2002 monitored Site Hydrology Average depth to groundwater below 19.31 feet Average increase(+)/decrease(—)in -2.37 feet monitoring well measuring points depths to groundwater since last sampling (Shallower) Approximate flow direction and 0.0036 ft/ft Northeast as calculated using monitor oundwater gradient wells MW-2,MW-6, and MW-8. Groundwater Contamination Monitor wells containing free product None Monitor wells with detected odors 0 Number of wells with concentrations 4 Number of wells with concentrations at or 3 ' below the MTBE MCL(13 It ) above the benzene and/or MTBE MCLS Nature of contamination: Range of analyte concentrations detected in the monitor wells: MTBE MTBE(}tg/L) <0.5—23,000 Gasoline TAME(gg/L) <0.5—75 Oxygenates TBA(gg/L) <0.5 —63 /Additives * Monitor wells MW-4 and MW-5 were not sampled;MW-4 purged dry during sampling and did not recharge and MW-5 was dry FIELD OBSERVATIONS 10 On December 27, 2002, a Condor representative was on site to measure water levels in all nine monitoring wells and collect groundwater samples from monitoring wells MW-1 through MW-9 as part of the fourth quarter 2002 quarterly groundwater monitoring event. Monitoring well MW-5 was dry, and MW-4 contained significant sediment and was purged dry during sampling and did not recharge; thus, groundwater samples were not collected. The locations of the monitoring wells are shown in Figure 2, Attachment A. Field observations included water level measurement (Table 2, 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 in Attachment C. Floating product, sheen, and odors associated with petroleum hydrocarbons were not observed in the groundwater purged from the monitoring wells during the groundwater sampling. The groundwater purged from MW-1, MW-2, MW-3, MW-6, MW-7, MW-8, and MW-9 contained a significant amount of suspended sediment. Poor clarity was noted in the field inspection purge groundwater sample from MW- 4, and MW-8; moderate clarity was noted in MW-7. The purged groundwater from MW-1, MW-2, MW- 3, and MW-6 turned brown with poor clarity on the second purge volume withdrawn. The purged groundwater from MW-9 turned brown with moderate clarity after approximately 4.5 gallons were purged from the well. GROUNDWATER ELEVATIONS AND GRADIENT ' Groundwater elevations fluctuated relative to the previous quarterly monitoring event (September 2002). The average groundwater elevation increased with respect to the previous quarterly monitoring event by -Amok 7 2-7 F-t F« AX117 1 �1 �,,. .1 A4111_A —A 14117 L �L_�__�L n 4'tAr n �______�__ _,___ -I- _ i_ �....,. .... -a ---6- —T-- u11u lri rr-V L111Vur'11 iV1 YY-7. V1VU1AUWaLrI CIGVQLIUII UdL'd IS PIrSr11LCU in Table 2, on the following page, and historic groundwater elevation data is included in Attachment D. iM� CONDOR