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Former Canteen Facility January 20, 2003 QRarteTly Groundwater Monitoring Report Pa e 3 ITAME 1,2-DCA and EDB The samples were transported under chain-of-custody using an overnight delivery service to McCampbell Analytical, Inc , of Pacheco, California, a California Iaccredited analytical laboratory IGROUNDWATER CONDITIONS The following summarizes the local groundwater gradient and the groundwater analytical results Groundwater Gradient Interpretation of the monitor well gauging data for this quarter indicates a south- southwest hydraulic gradient across the Site of approximately 0 001 ft/ft Figure 2 illustrates the groundwater contours and gradient for this gauging event The groundwater gradient is consistent with past gauging events The change in water levels is a result of cyclical fluctuations in the weather and the proximity of the site to the Stockton Diverting Canal, located approximately 1000 feet to the northeast The ' historical groundwater elevations are summarized on Table 1 ' Groundwater Analytical Results Groundwater analytical results are compared to the California Department of Health ' Services Drinking Water Standard Maximum Contaminant Levels (CAMCL) Analysis of the groundwater samples obtained from the seven Site monitor wells indicated the following ' • Benzene was detected in groundwater samples from monitor wells MW-3, MW- 3D, and MW-13A at concentrations of 4 9, 55, and 0 59 µg/l, respectively The ' groundwater samples taken from monitor wells MW-3 and MW-3D exceeded the CAMCL for benzene of 1 0 µg/l ' • Toluene was detected in monitor wells MW-3, MW-3A, MW-3D, and MW-13A at concentrations ranging from 12 to 5 1 µg/1 No samples exceeded the CAMCL for toluene (150 µg/l) ' . Ethylbenzene was m detected monitor wells MW-3, MW-3D, and MW-13A at concentrations of 0 67, 51, and 0 73 µg/l, respectively No samples exceeded the ' CAMCL for ethylbenzene (700 pg/1) ' �Euutar 0