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3.4.2 Site Geology and Soil Types The Site lies within the east-central part of the Great Valley Geomorphic Province of California. The valley is approximately 400 miles long and averages 50 miles wide. The valley has been filled with a thick sequence of marine and nonmarine sediments dating from the late Jurassic to the Holocene periods. 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. According to the Geologic Map of the Sacramento Quadrangle [California Division of Mines & Geology, 1981],the Site is underlain by arkosic alluvium of the Quaternary Modesto-Riverbank Formation. According to the Soil Survey of San Joaquin County [USDA Soil Conservation Service, 1992], the Site is underlain by Bruella sandy loam, hard substratum. The Bruella series consists of very deep soils formed in alluvium from granitic rock sources. The soils are well to moderately well drained, with slow runoff and moderately slow permeability. The hard substratum phase has slow permeability below a depth of about 40 inches. 3.4.3 Site Hydrogeologic Setting The Site lies in the northern portion of the Eastern San Joaquin County Ground Water Basin [DWR, 1980]. Staff of the San Joaquin County Flood Control and Water Conservation District report that groundwater in the Lockeford area exists under unconfined conditions. Based on the Spring 1999 groundwater elevation contour map produced by San Joaquin County, the water table elevation at the Site was about 10 feet below sea level, or 110 feet bgs, and the groundwater flow direction was generally toward the southeast away from the Mokelumne River. In April 1997, groundwater was measured at 117 feet bgs in a water supply well at the existing school adjacent to the Site, which is consistent with the contour map produced by the County. According to data presented in the County's September 2001 Water Management Plan(Volume 2), the elevation of water in a well located about two miles southeast of the Site varied between about 10 and 30 feet below sea level during the period of 1990 to 1998. 3.4.4 Site Climatological Setting The monthly mean of the daily (24-hour) temperature in the Lodi area ranges from about 45 degrees Fahrenheit in winter to 73 degrees Fahrenheit in summer, and the average annual rainfall is about 19 inches (www.worldclimate.com). 3.5 CURRENT AND HISTORICAL LAND USES 3.5.1 Property Ownership All three parcels that comprise the Site are owned by Douglas H. and L.K Winn. Page 10 PAPEA Lockeford\Work PIanU ockeford WP.doc