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(IVYATC <br /> • A S 5 0 C I A T E S I N C <br /> TPHg and TEX were detected in the groundwater sample collected from monitoring well MW3 at <br /> concentrations of 1,800 µg/L, 2 0 µg/L, 16 µg/L, and 11 pg/L, respectively None of the gasoline <br /> oxygenates/additives were detected in the sample collected from MW3 <br /> The Maximum Contaminant Level (MCL) for benzene, 1 jig/L, was exceeded in a groundwater <br /> sample collected from monitoring well MWI <br /> GROUNDWATER FLOW DIRECTION <br /> Water level measurements were collected from monitoring wells MW1, MW2, and MW3 on <br /> September 10, 2003 Water level elevations ranged from 35 69 to 35 74, representing an average <br /> decrease in water table elevation of approximately 2 22 feet since June 2003 The water level data <br /> were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal <br /> Isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed toward the <br /> northeast The average hydraulic gradient on September 10, 2003 was calculated to be 0 0008 or <br /> approximately 4 ft/mile Summaries of groundwater monitoring data and analytical results are <br /> presented in Table 1 and Table 2, respectively <br /> CONCLUSIONS <br /> Groundwater flow direction and gradient is generally consistent with previous sampling events <br /> Water table elevations have generally decreased since monitoring was initiated at the site in 1999 <br /> The groundwater elevations represent historical lows Groundwater analytical results remained <br /> within historical parameters as set by previous groundwater analytical results <br /> RECOMMENDATIONS <br /> Based on the results of the third quarter 2003 monitoring event, we recommend continued quarterly <br /> groundwater monitoring and completion of the ten biweekly groundwater extraction events from <br /> monitoring well MW1 The tenth biweekly groundwater extraction event is scheduled to be <br /> conducted in the month of November <br /> Please contact our office at(209) 579-2221 if you have any questions or comments <br /> Respectfully submitted, <br /> ATC Associates Inc <br /> Todd Hafner eanne Homsey, P E <br /> Project Geologist CA Registered Civil Engineer No 47410 <br /> cc Mr Paul Van Dyken, Sr,N & S Irrigation <br /> 46 Jim Barton, RWQCB <br /> Attachments <br /> s lenvironmentai\149811Reportsl3QR-03 doe 3 <br />