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KLEINFELDER File No. 20-3978-O1.W10 July 26, 1997 The remaining area, bordered by the residential development and property boundary on the west and Spreckels Avenue on the east, is proposed for a office/business park consisting of seven lots on approximately 83.5 acres. The southernmost boundary of the office/business park would include another park/stormwater basin. For further details regarding the proposed land use please refer to the attached copy of the Tentative Map. 2.4 Geology And Hydrogeology The site lies within the Great Valley Geomorphic Province of California. The valley is approximately 400 miles long and averages about 50 miles wide, and comprises about 20,000 square miles. The valley has been filled with a thick sequence of marine and non-marine sediments from the late Jurassic to Holocene. The uppermost strata of the Great Valley represents, for the most part, the alluvial, flood, and delta plains of two major rivers (Sacramento and San Joaquin Rivers)and their tributaries. The valley deposits are derived from the Coast Ranges to the west and the Sierra Nevada to the east. Granitic and metamorphic rocks outcrop along the eastern and southeastern flanks of the valley. Marine sedimentary rocks outcrop along most of the western, southwestern, southern, and southeastern flanks; and volcanic rocks and deposits outcrop along the northeastern flanks of the valley. The valley geomorphology includes dissected uplands, low alluvial plains and fans, river flood plains and channels, and overflow lands and lake bottoms. The majority of the native sediments near the site consist of Miocene to Holocene continental rocks and deposits of a heterogeneous mixture of generally poorly sorted clay, silt, sand, and gravel. Some beds of claystone, siltstone, sandstone, and conglomerate are also present. Site specific geologic information was obtained from two documents prepared for Spreckels Sugar by Kenneth D. Schmidt, Groundwater Quality Consultant (Schmidt 1985 and Schmidt 1993). The documents are technical reports on groundwater monitoring efforts associated with the wastewater, lime and mud ponds on site. According to Mr. Schmidt, coarse-grained alluvial deposits, primarily fine to medium grained sand, are present to a depth of at least 60 feet below grade. Localized clay strata are also present in the upper 60 feet. Additionally, two major clay layers are present beneath the site at approximate depths of 95 to 141 feet, and 188 to 243 feet. Mr. Schmidt identifies the deeper clay layer (188 to 243 feet) as the Corcoran Clay, a major regional confining bed that occurs along the west side of the San Joaquin Valley. Mr. Schmidt indicates that several major gravel deposits occur at depths of 40 to 65 feet, 110 to 130 feet, and 300 to 340 feet below the site. The deepest gravel layer is reportedly the aquifer tapped by the factory water supply wells. 20-3978-01.WIO 12017LI55 Page 4 of 50 Copyright 1997,Kleinfelder,Inc.