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2.2 Estimates of Liquid Quantity and Composition Leaked: No estimate of the quantity of liquid contaminant leakage can be determined from existing information. Based on analytical results, the soil contamination appears to be comprised of diesel and gasoline constituents. 2.3 Topography, Geology, Hydrology The site is situated in central Escalon in Section 4, T2S, R9E, San Joaquin County, California. Regionally the property is located in the San Joaquin Valley physiographic province. The valley is a topographic and structural basin bounded on the east by the Sierra Nevada and on the west by the Coast Ranges. Locally the topography slopes gently toward the west at approximately 5 feet per mile. The StanisIaus River is 2.5 miles to the south and Woodward Reservoir is located approximately 7 miles to the northeast (USGS Escalon Quadrangle, 1968). The near surface geology underlying the site is dominated by unconsolidated alluvial deposits of Pleistocene to Holocene age. These deposits, sometimes referred to as the "older alluvium", consist of intercalated beds of gravel, sand, silt and clay. The thickness of the older alluvium in the Escalon area averages approximately 450 feet. Underlying the older alluvium are Plio/Pleistocene continental deposits of similar derivation and lithology. The older alluvium -- functions as the most important aquifer in the site area (USGS Professional Paper, 1401-C, 1986). Soils developed on the alluvium are generally well drained, differing from the parent material _. only in the increased volume of organic matter(DWR Bulletin No. 146, 1967). The important bodies of surface water in proximity to the site are the Stanislaus, Tuolumne, and San Joaquin rivers. The Stanislaus and Tuolumne, respectively, are located approximately 2 1/2 and I0 1/2 miles to the south of the site area. These two rivers flow in a westerly direction and are tributaries to the San Joaquin, located approximately 14 miles-west of the site. The northerly flowing San Joaquin drains the San Joaquin Valley. All three of these are gaining streams and derive a significant portion of their flow from groundwater influx (USGS Professional Paper, 1401-C, 1986). FM205MI. �werm�n" ®fII�RI.