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rM <br /> QUARTERLY pRCDND WATER MONITORING REPORT <br /> 1199 E.Yosemite Avenue,Manteca,California <br /> 3.0 DISCUSSION <br /> Presented below is a summary of results of Aegis' groundwater elevation monitoring and <br /> groundwater analytical testing. <br /> 3.1 Groundwater Elevations <br /> Groundwater elevations were observed to range from 14.49 to 14.55 fleet above mean sea <br /> level on the 1 February 1991 sampling event. The groundwater surface was observed to <br /> be approximately 26 feet below existing grade. Based on groundwater elevation contouring <br /> of the water level measurements, the hydraulic flow direction has continued in a west to <br /> northwesterly direction. The calculated ave,age hydraulic gradient for the February 1991 <br /> data was approximately 0.002 feet per foot (ft/ft). <br /> A groundwater elevation contour map was drafted from the groundwater elevations <br /> measured on 1 February 1991 and is presented as Figure 3. This contour map indicates <br /> the flow direction and calculated hydraulic gradient. <br /> A monitoring well hydrograph has been prepared showing the fluctuation of groundwater <br /> levels with time since the installation of the wells. The hydrograph is included as Figure 4. <br /> 3.2 Groundwater Analytical Results <br /> Monitoring wells were purged and groundwater sample were collected from each well <br /> according to Aegis' SOP, Appendix A. <br /> The highest concentrations of petroleum hydrocarbons in water continued to be observed <br /> in MW-1A. MW-2 and MW-3 continued to show low levels of petroleum hydrocarbons. <br /> Laboratory analyses of groundwater samples are summarized in Table 3. <br /> These results will be compared to ensuing groundwater sampling/results to determine if <br /> these conditions are an anomaly or a changing trend in groundwater chemistry. <br /> 4.0 SCHEDULE <br /> The next quarterly monitoring is scheduled for the beginning of May 1991. <br /> 90-090A.APT '�' - <br />