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GEOMATRIX this interval, which grades downward into loose, dark gray to greenish-gray, poorly-graded ' sand This dark gray sand was observed in all three borings from approximately 30 to 41 feet bgs, the total depth explored ' Data from nearby studies indicate that the depth to groundwater in the vicinity ranges from about 5 to 10 feet bgs (SPGC, 1998, and EMCON, 1998) Seasonal fluctuations in the water ' table appear to range from about 3 to 5 feet, with some as much as 6 to 9 feet Tank removal inspection records for Port sites (dating back to 1987) indicate that no groundwater was encountered during excavation or soil resampling to a depth of as much as 16 feet bgs Water levels in this area have risen as much as 8 feet since 1994, 2 to 3 feet of which appear to be ' attributable to the heavy and prolonged El Nino rainfalls the winter of 1997198 Water levels measured in the three initial bonngs at Site 3 on August 7, 1998 ranged from about 9 5 to ' 12 feet bgs Based on nearby studies (SPGC, 1998 and EMCON, 1998) groundwater flow directions in the vicinity appear to be variable, ranging from west northwest to east southeast Flow direction changes may be due to tidal influences produced by the deep-water channel to the north and the San Joaquin River to the west and southwest of the Port complex 1.4 REvrEw OF MONITORING DATA Monitoring data, including groundwater levels and groundwater samples, have been collected from the site on a quarterly basis since July 1999 Samples have been analyzed for TPH-g, benzene, toluene, ethylbenzene, and xylenes (BTEX), and on several occasions for MTBE In addition, field parameters (temperature, electrical conductivity, and pH) are measured prior to sample collection at each monitoring event IGroundwater levels during the period of record have ranged from about 9 to 12 feet bgs (Table 1) Groundwater flow directions are variable, ranging, in a clockwise sense, from northwest to southwest (Figure 2) Gradients have also been variable, ranging from about 0 004 to 0 035 feet per foot No seasonality is apparent in the flow direction or gradient Water quality samples collected to date indicate significant variability in concentrations of PHCs TPH-g concentrations have ranged from 180 to 8,800 µg11 and benzene concentrations have ranged from 3 8 to 886 gg/l (Table 2) No MTBE has been detected in any of the monitoring wells The lowest TPH-g concentrations have generally been in MW3-1 and the highest in MW3-3, although benzene concentrations are generally highest in MW3-2 No discernable trends in PHC concentrations (either up or down) have been detected in any of the monitoring wells I\PROIEC'IW37 000/6437 Wk PIn Site 3 doc 4