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tD E4 Former Canteen Facility January 14, 2003 uarterl Groundwater Momtorm Re ort Pncre 3 overnight delivery service to McCampbell Analytical, Inc , of Pacheco, California, a California accredited analytical laboratory GROUNDWATER CONDITIONS The following summarizes the local groundwater gradient and the groundwater analytical results Groundwater Gradient Interpretation of the monitor well gauging data indicates that there is a southwesterly hydraulic gradient across the Site of approximately 0 001 feet/foot Figure 2 illustrates the groundwater contours and gradient for this gauging event The gradient appears to be 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 six Site monitor wells indicated the following • Benzene was detected in the groundwater sample from monitor wells MW-3, MW-3D, and MW-13A at concentrations of 6 7, 19, and 0 72 µg11, respectively The CAMCL for benzene is 10 µg/l, exceeded in MW-3, MW-3D, and MW-13A • Toluene was detected in monitor well MW-3, MW-3A, MW-3D, and MW-13A at concentrations of 2 7, 2 9, 1 8, and 1 5 µg11, respectively The CAMEL for toluene is 150 µg/1 • Ethylbenzene was detected in monitor wells MW-3 and MW-3D at concentrations of 1 4 and 21 ug/l, respectively The CAMCL for ethylbenzene is 700 µg/1 • Total xylenes were detected monitor wells MW-3, MW-3D, and MW-13A at concentrations of 0 91, 5 1, and 2 5 µg/1, respectively The CAMCL for xylenes is 1,750 µg/L