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ca e . Qf1AR rERLY GROUND WA-ER MONITORIN[3 REPORT ~� 5491 F Strent,Banc CA11fornia 3 , r-. 1.0 ®UARTcRLY MONITORiNG RESULTS Presented below is a summary of the results of Aegis' ongoing groundwater elevation monitoring and groundwater sample analytical testing. 3.1 Groundwater rtlevatlons ri During the 1 February 1991 site visit, groundwater elevations were observed to ran,>e from 12.31 to 12.51 feet above mean sea level. The groundwater surface was observed t o range _. from approximately 13 to 14 feet below existing grade. Based on groundwater elevation contouring by the SURFER®computer program using the Kriging method,the hydraulic flow �.• direction, is in an easterly direction. The average hydraulic gradient across the site for the i 1 February 1991 data was approximately 0.002 feet per foo# ( / )ft ft , A groundwater elevation contour map was drafted from the groundwater elevations measured on i February 1991 and is presented as Figure 3. This contour ma indi l direction and calculated hydraulic gradient. p Cates the flow t ^. A monitoring well hydrograph has been prepared showing the fluctuation of groundwater levels with time since the installation of the wells. The hydrograph is included as Figure 4. I } 3.2 Ground►yater qna! ical Results 1 �-r Monitoring wells were purged and groundwater samples were obtained according to Aegis' OP, Appendix A. S Concentrations of dissolved petroleum hydrocarbons in groundwater were reported below detectabia levels in all wells except MW-1 for the 1 February 1991 sampling event. Laboratory analyses of the groundwater samples collected from the monitoring s wel are summarized in Table 2. These results will be compared to ensuing groundwater sampling results to determine if the 1 data is reproducible or if thane is a changing trend in groundwater chemistry or flow. i X13 4.t) SCHE1dUl.E r The nerd quarterly monitoring is scheduled{:. g led for May 1991. - i t i