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3 SITE SETTING 3.1 SITE LOCATION The Schmiedt Property / Former Tri-Ag Services, Inc. facility is located at 20696 South Main Street, in Manteca, California. Please see Plate 1. 3.2 CURRENT USE AND SITE CHARACTERISTICS The site occupies 11/4 acres (and has historically occupied up to 5 acres). The site consists of mostly unpaved land and has one office building, one shop building, a residence, a former pesticide storage container, drums, a rinseate pad, a rinseate storage tank, a truck fueling pad, a drinking water well, and miscellaneous field equipment stored on site. 3.3 REGIONAL GEOLOGY AND HYDROLOGY The site lies within the central portion of 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 represent, 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. Review of the California Division of Mines and Geology "Geologic Map of the San Francisco — San Jose Quadrangle," indicates that the site is underlain by Quaternary alluvial fan deposits of the Modesto Formation. Based upon the San Joaquin County Flood Control and Water Conservation District, Spring 1999 Groundwater Report, shallow groundwater in the vicinity of the site is approximately 10 to 20 feet below existing grade. The regional direction of groundwater flow is toward the northwest. I. 27125.E01 / STO4R181 0 2004 Kleinfelder, Inc. KLEINFELDER 2825 East Myrtle Street, Stockton, CA 95205-4794 (209) 948-1345 (209) 948-0621 fax Page 6 of 23 February 13, 2004