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Working To Restore Nature <br /> 3.0 REGIONAL GEOLOGY AND HYDROLOGY <br /> tThe site is situated in central Escalon in Section 4, T2S, R9E, San Joaquin County, California <br /> Regionally the property is located in the San Joaquin Valley physiographic province The valley <br /> is a topographic and structural basin bounded on the east by the Sierra Nevada and on the west <br /> by the Coast Ranges Locally the topography slopes gently toward the west at approximately <br /> ' 5 feet per mile <br /> The near surface geology underlying the site is comprised of unconsolidated alluvial deposits of <br /> ' Pleistocene to Holocene age These deposits, sometimes referred to as the "older alluvium", <br /> consist of intercalated beds of gravel, sand, silt and clay The thickness of the older alluvium <br /> in the Escalon area averages approximately 450 feet Underlying the older alluvium are <br /> Plio/Pleistocene continental deposits of similar derivation and lithology The older alluvium <br /> functions as the most important aquifer in the site area (USGS Professional Paper, 1401-C, <br /> 1986) <br /> Soils developed on the alluvium are generally well drained differing from the parent material <br /> only in the increased volume of organic matter (DWR Bulletin No 146, 1967) The important <br /> bodies of surface water in proximity to the site are the Stanislaus, Tuolumne, and San Joaquin <br /> ' Rivers The Stanislaus and Tuolumne Rivers, respectively, are located approximately 2 112 and <br /> 10 112 miles south of the site These two rivers flow in a westerly direction and are tributaries <br /> to the San Joaquin River, located approximately 14 miles west of the site The northerly flowing <br /> San Joaquin River drains the San Joaquin Valley All three of these rivers are gaining streams <br /> Iover portions of the year and derive a portion of their flow from groundwater influx (USGS <br /> Professional Paper, 1401-C, 1986) <br /> The primary uses of groundwater in the area include irrigation and both private and municipal <br /> water supply The "older alluvium" is the most extensively developed geologic unit in the area <br /> and hosts both unconfined and confined zones The unconsolidated, mostly coarse grained <br /> ' 1500471R-031594 FNL 2 <br /> r <br />