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V <br /> SCEs' <br />' chain-of-custody to McCampbell Analytical, Inc , of Pacheco, California, a California accredited <br /> analytical laboratory <br /> GROUNDWATER CONDITIONS <br /> The following sections summarize the local groundwater gradient and the groundwater analytical <br /> results <br />' Groundwater Gradient <br /> Interpretation of the monitor well gauging data indicates that there is a south - <br />' southwesterly hydraulic gradient across the Site of approximately 0 002 feet/foot Figure 2 <br /> presents the groundwater gradient map prepared by AES for this gauging event The <br /> gradient appears to be consistent with past gauging events The drop in water levels is a <br /> result of cyclical fluctuations in the weather and the proximity of the site to the Stockton <br /> Diverting Canal, located approximately 1000 feet to the northeast The historical <br /> groundwater elevations are summarized on Table 1 <br /> Groundwater Analytical Results — Contaminant Concentrations <br /> Groundwater quality data are compared to the California Department of Health Services <br /> Drinking Water Standard Maximum Contaminant Levels (CAMCL) Analysis of the <br /> seventeen groundwater samples obtained from the on-Site monitor wells indicated the <br /> rfollowing <br /> • Benzene was detected in groundwater samples from monitor wells MW-1, MW-3, <br /> MW-3A, MW-3D, MW-8, MW-13, and MW-13A at concentrations ranging from <br /> 0 75 to 13,000 µg/1 The CAMCL for benzene is 1 0 µg/l Benzene <br />' concentrations exceed the CAMCL in MW-I, MW-31), MW-13 and MW-13A <br /> The benzene concentrations in MW-1 have increased However, the concentrations <br /> have decreased in MW-3D, MW-13 and MW-13A since September 2000 <br /> 1 • Toluene was detected in monitor wells MW-1, MW-3, MW-3A, MW-3D, MW-5, <br /> MW-8, MW-13, MW-13A and MW-13B at concentrations ranging from 0 72 to <br />' 20,000 µg/1 The CAMCL for toluene is 150 µg/l Toluene concentrations only <br /> exceeded the CAMCL in MW-13 Concentrations of toluene increased in MW-1, <br /> MW-3, MW-3A, MW-3D, MW-5, MW-8 and MW-1313, and decreased in MW-13 <br />' and MW-13A <br /> • Ethylbenzene was detected in monitor wells MW-1, MW-3A, MW-3D, MW-8, <br />' and MW-13 at concentrations ranging from 0 51 to 2,700 µg/1 The CAMCL for <br />' Canteen Facility January 15, 2001 <br /> Quarterly Groundwater Monitoring Report Page 3 <br />