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2.0 ENWRONMENTAL SETTING Descriptions of the environmental characteristics and physical setting of the subject property are based upon a reconnaissance of the site and review of readily available information. 2.1 Topography Manteca is located in the northern part of the San Joaquin Valley, which is the southern portion of the larger Central Valley of California. The Central Valley is approximately 450 miles long and ranges from 30 to 70 miles wide bounded by the Sierra Nevada Mountains to the east, the Coastal Mountains to the west, the Cascade and Klamath Mountains to the North, and the Tehachapi Mountains to the south. The topography of the San Joaquin Valley is relatively flat sloping gently from the mountains to the east and west toward the San Joaquin River that lies more or less along the central axis of the valley. The terrain of the general area was essentially flat sloping gently to the west toward the San Joaquin River and generally traversed by low-gradient streams, canals, and developed urban areas. Elevations range in the general area range from roughly 40 feet above mean sea level (amsl) about one mile east of the site to approximately 25 feet amsl about one mile west of the subject property. The US Geological Survey 7.5- minute Quadrangle Map with coverage of the subject property (Manteca, California) depicted the site as relatively flat terrain at an elevation of approximately 35 feet amsl. Natural elevation change across the subject property appears to be 3 to 5 feet. 2.2 Geology San Joaquin County is located within the Great Valley physiographic province, which is a structural trough filled with volcanogenic debris and pelagic sedimentary deposits up to 32,000 feet in thickness and dipping relatively uniformly from each side of the valley toward its central axis. However,these deposits are generally a few thousand feet deep across the majority of the Great Valley. Three primary geologic units lie beneath San Joaquin County, including the metamorphic and igneous basement rock complex, unconsolidated marine sediments, continental deposits, and unconsolidated alluvium derived from fluvial systems originating from higher elevations to the east. The area about the subject property resides on recent alluvial, river channel, and floodplain deposits, which are underlain by the Modesto, Riverbank, Turlock Lake,Mehrten, lone, and Valley Springs Formations. Typical near surface sediments consists of poorly sorted sands and silty sands with interbedded silts, clayey sands, and clay. Typical thicknesses of near surface alluvial deposits, Modesto, and Riverbank Formations generally range from 100 to 300 feet below ground surface (bgs). The Mehrten Formation is composed of sandstone, breccia, conglomerate, tuff siltstone and claystone ranging to 1,000 feet in thickness. 2.3 Soils The Natural Resources Conservation Service (NRCS) has compiled soil survey data for San Joaquin County. Soils in the site vicinity are identified as `Delhi-Urban Complex' in the Soil Survey of San Joaquin County, California. The Delhi series consists of very deep, somewhat excessively drained soils formed in wind modified material weathered from granitic rock sources. Delhi soils are on floodplains, alluvial fans and terraces on slopes ranging from 0 to 15 percent at elevations between 25 to 1,400 feet amsl. These soils are somewhat excessively drained with negligible to slow runoff and rapid permeability. Urban complex is generally inclusive of native and non-native soils and engineered and artificial fill materials. Zions First National Bank Limited Subsurface Investigation 6 Valentine Properties—Manteca,California 00'a"Uch—