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V t Harding Lawson Associates Review of a groundwater contour map for the fill of1990'i(SJCFCWCD, 1990), 4 x indicates that the site vicinity is on the west side of a groundwater drawdown trough with the regional groundwater,flow direction to the east' Recharge to the aquifers occurs primarily as a result of infiltration of excess irrigation water, stream flows and to a lesser degree rainfall, and underflow from �1 tributary stream canyons. 6.2 Site Hvdroaeoloey Review of the excavation wall logs indicates the shallow soils at the site consist of a thin surfical layer of brown silty sand extending from the ground surface to a depth of I to 2 feet. Brown and grey, medium stiff to stiff sandy clay was encountered from depths of .between 1 and 2 feet to between 4 and 5 feet. On the southern portion of the excavation, brown medium stiff sandy silt was encountered from 4 feet to the bottom of the excavation at 6.5 feet. 5 Review of the hydrogeologic information contained in the reports of identified cases of sail and groundwater contamination within 0.5 miles of the site indicate that the soils in the site vicinity to depths of approximately 70 feet consist of laterally discontinuous interbedded clay, silty clay, silt, clayey sand, and sand. Groundwater + .levels were reported to be between.47 and 60 feet.in 1988 through 1991, with �tgroundwater flow directions to the northeast, southeast, and east. These reports indicate that the shallow aquifer in the site vicinity is unconfined, consisting of thin and I discontinuous sand and clayey sand units with clay and silt interbeds. The groundwater table in the site vicinity in the fall of 1990, presented in SJCFCWCD, 1990, is at an elevation of 50 feet below sea level. As the site elevation is approximately 13 feet, the depth to groundwater at the site in Fall 1990 was approximately 63 feet. 6V T19461-H 14 of 20