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CV4%TC • A S S O C I A T E S I N C GROUNDWATER FLOW DIRECTION Water level measurements were collected from monitoring wells MW 1, MW2, and MW3 on March 21, 2001 Water level elevations ranged from 38 91 to 39 00, representing an average decrease in water table elevation of approximately 0 41 feet since December 2000 The water level data were used to develop the groundwater elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the north-northeast The average hydraulic gradient on March 21, 2001 was calculated to be 0 001 or approximately 7 2 ft/mile A summary of groundwater monitoring data is presented in Table 1 ADDITIONAL FIELD WORK On March 21, 2001 monitoring wells MWI, MW2, and MW3 were resurveyed for elevation Monitoring well MW 1 was set at an arbitrary elevation of 65 feet above mean sea level based on USGS 7 5 Minute Topographic Quadrangles, Manteca, Ripon, and Salida The results show that the original survey elevations were correct CONCLUSIONS Groundwater flow direction and gradient is consistent with previous sampling events Water table elevations have decreased slightly since the December 2000 monitoring event Groundwater matrix analytical results remained within historical parameters as set by previous groundwater matrix analytical results RECOMMENDATIONS Based on the results of the first quarter 2001 monitoring event, we recommend continued quarterly groundwater monitoring with analysis of samples for TPHg and BTEX Please contact our office at (209) 579-2221 if you have any questions or comments Respectfully submitted, ATC Associates Inc &oSellman Geologist JU O Jeanne Hornsey, P E CA Registered Civil Engineer No 47410 A-'40 cc Mr Paul Van Dyken, Sr,N & S Irrigation Marty Hartzell, RWQCB - w lwordpro11498111QR-0l doc 3