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4. <br /> Canepa's Car Wash <br /> 6230 Pacific Avenue,Stockton,CA <br /> Fourth Quarter Groundwater Monitoring Report,November 2003 <br /> Page 3 of 6 <br /> • GROUNDWATER ELEVATIONS AND GRADIENT <br /> Groundwater elevation contours estimated for the shallow monitor wells (MW-1, MW-3, MW-4, MW-6, <br /> MW-7, MW-9, and MW-11) on November 9, 2003, indicate that the groundwater gradient is to the <br /> northeast and is generally consistent with previously estimated groundwater gradients (Figure 2, <br /> attached). Unfortunately, four of the site monitor wells historically used to estimate the groundwater <br /> gradient/elevation were not utilized during the November 2003 monitoring event. Monitor wells MW-5 <br /> and MW-10 were paved over and not located until November 10, 2003. The water level data obtained <br /> from monitor wells MW-2 and MW-11 is believed to be erroneous. The data collected from monitor wells <br /> MW-2 and MW-11 differs significantly from the historical groundwater gradient and water level data for <br /> the current event from site monitor wells in close proximity to monitor wells MW-2 and MW-11. Monitor <br /> well MW-12D was not used in groundwater elevation contouring due to the well's deep screen interval. <br /> An estimated groundwater gradient of .0049 ft/ft towards the northeast was measured using water level <br /> data from monitor wells MW-6 and MW-9. The average depth to groundwater measured in the seven <br /> monitor wells at the site that were used in contouring and averaging for this event increased by <br /> approximately 1.96 feet since July 25, 2003. A hydrograph of historic groundwater elevations is attached <br /> as Figure 3. It should be noted that the top of the well screens for shallow monitor wells MW-1 through <br /> MW-7 were below the water table, consistent with much of the monitoring history at the site. <br /> Table 2 <br /> Groundwater Elevation Data (November 9, 2003) <br /> Well Casing Well Collar Depth to Groundwater <br /> Screen <br /> WELL Elevation Water Elevation <br /> ( <br /> • lnterval feet <br /> feet-b s ) (feet) (feet) <br /> MW-1 50-70 15.48 38.53 -23.05 <br /> MW-2 50-70 15.29 37.17* -21.88* <br /> MW-3 50-70 15.53 39.07 -23.54 <br /> MW4 1 50-70 15.83 39.25 -23.42 <br /> MW-5 50-70 14.71 # # <br /> MW-6 45-65 14.89 37.44 -22.55 <br /> MW-7 45-65 15.80 38.50 -22.70 <br /> MW-9 25.45 14.84 38.52 -23.68 <br /> MW-10 25-45 14.72 # # <br /> MW-11 25-45 15.12 38.88* -23.76* <br /> MW-12D 100-110 14.99 37.79 -22.80 <br /> *Water level data believed to be erroneous <br /> #Monitor well paved over,water level data not obtained <br /> • <br /> �'� CONDOR <br />