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Former Canteen Facility June 24,2003 uarterl Groundwater Monrtonn Re ort Page 3 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 west - 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 i 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-3D, MW- 13, and MW-13A at concentrations of 7 7, 29,000, and 0 84 µg11, respectively The groundwater samples taken from monitor wells MW-3 and MW-13 exceeded the CAMCL for benzene of 10 µg/1 • Toluene was detected in monitor wells MW-13 and MW-13A, at concentrations of 42,000 and 2 3 µg/1, respectively The CAMCL for toluene is 150 µg/1, exceeded only in MW-13 • Ethylbenzenc was detected in monitor wells MW-3D, MW-13, and MW-13A at concentrations of 6 2, 3,000, and 3 2 µg/1, respectively The CAMCL for ethylbenzene is 700 pg/l, exceeded only in MW-13 • Total xylenes were detected in monitor wells MW-3, MW-3D, MW-13, and MW- 13A at concentrations of 2 9, 2 2, 24,000, and 2 3 4g/1, respectively The CAMCL for xylenes is 1,750 µg/L, exceeded only in MW-13 0 �u LICES~