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<br /> Fourth Quarter 2003 Groundwater Monitoring Report
<br /> Boyett Petroleum,419 S.Main,Manteca,CA
<br /> Page 2
<br /> INTERiIVI iyiONTHLY GROUNDWATER MONITORING ACTIVITIES
<br /> A provisional increase in the groundwater monitoring frequency was initiated in July 2003. For a period
<br /> of six consecutive months, water levels in monitoring wells MW-1 through MW-3 and MW-6 through
<br /> MW-9 were measured on a monthly basis and groundwater samples collected for MTBE laboratory
<br /> analysis. Monitoring wells MW-1, MW-4, and MW-5 were destroyed on October 29, 2003. Three on-site
<br /> groundwater monitoring wells (MW-4R, MW-10, and MW-11) and one extraction well (EW-1) were
<br /> installed on October 30, 2003.
<br /> The locations of the monitoring wells are shown in Figure 2, attached. Field observations are included on
<br /> the Groundwater Monitoring Field Forms, attached.
<br /> OCTOBER 31 2003 MONTHLY MONITORING EVENT
<br /> On October 31, 2003, a Condor representative was on site to measure water levels and collect
<br /> groundwater samples for MTBE laboratory analysis from monitoring wells MW-2, MW-3, MW-6, MW-
<br /> 7, MW-8, and MW-9. Monitoring wells MW-2, MW-6, and MW-7 were dry and monitoring wells MW-3
<br /> and MW-8 had an insufficient water column for purging to be effective; as a result, a groundwater sample
<br /> was collected only from monitoring well MW-9. At the time of the October 2003 monitoring event, MW-
<br /> 4R, MW-10, MW-11, and EW-1 had not yet been developed; thus, monthly monitoring activities were
<br /> not conducted.
<br /> Field observations included water level measurement, appearance of samples (color, clarity, and presence
<br /> of petroleum product sheen or phase in samples), and collection of water quality field parameters. No
<br /> floating product, sheen, or odors associated with petroleum hydrocarbons were observed in the
<br /> • groundwater inspection samples from the monitoring wells during the October 31, 2003, groundwater
<br /> monitoring event.
<br /> Depth to groundwater measurements, relative to MW-3, MW-8, and MW-9, indicate that the groundwater
<br /> elevation decreased with respect to the September 2003 quarterly monitoring event. Groundwater
<br /> elevation contours and gradient could not be estimated due to the lack of data. Groundwater elevation
<br /> data for the October 2003 monitoring event are presented in Table 1, on the following page, and in Figure
<br /> 3, attached.
<br /> The groundwater sample collected from MW-9 was analyzed for MTBE by EPA Method 8260B by
<br /> Argon Laboratories, Inc. (Argon) of Ceres, California. Laboratory analytical results indicate that MTBE
<br /> was detected in the groundwater sample collected from MW-9. The laboratory analytical results for the
<br /> October 2003 monitoring event indicated a slight increase in the concentration of MTBE detected in the
<br /> groundwater sample collected from MW-9 relative to the previous sampling event conducted in
<br /> September 2003.
<br /> The laboratory analytical results for the October 31, 2003, groundwater monitoring event are presented in
<br /> Table 1, on the following page, and in Figure 4, attached. MTBE isoconcentration contours in groundwater
<br /> were not estimated for the October 2003 monitoring event due to the lack of data.
<br /> i
<br /> ILA CONDOR
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