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Phase II Environmental Site Assessment Manteca Multimodal Station Project, Southeast of Moffat Boulevard and Main Street,Manteca,California Coast Range and the Sierra Nevada,respectively. Rocks composing the basement complex of the province have not been completely defined but are believed to be of metamorphic and igneous origin. The Great Valley Province has been subdivided into two major sections identified as the Sacramento and San Joaquin Valleys. Site Geology The Geologic Map of the San Francisco-San Jose Sheet Quadrangle indicates the site is underlain by dune and eolian sand deposits. The United States Department of ALYriculture (USDA)web soil survey for the site indicates that the soil type present in the site vicinity is Delhi-Urban land complex. The Delhi soil is formed on wind-modified alluvium derived from granitic rocks and typically consists of very deep, excessively drained, loamy sand (upper 10- inches)and sand(10-inches to 60-inches depth). Urban Land Complex soils include areas covered by roads, driveways, sidewalks, parking lots, buildings, and other structures. Based on the previous assessment conducted at the site by Wm. J. Hunter and Associates in 1992,the following lithology was observed during the installation of a former onsite groundwater monitoring well: Surface layer of asphalt • 0 to 10 feet below grade: dark brown, slightly damp sandy loam 10 to 11.5 feet below grade: tan, moist, sandy loam • 11.5 to 15 feet below grade: tan clayey sand • 15 to 19.5 feet below grade: Clean, loose, slightly damp, coarse sand • 19.5 to 25 feet below grade: Damp, very coarse, clayey sand and gravel 0 25 feet below grade: first encountered groundwater • 25 to 35 feet below grade: very wet, loose, coarse sand and gravel During the current assessment,Rincon advanced five borings to 25 feet along the southern property boundary adjacent to the railroad right-of-way. Soil samples were collected at 5 foot intervals to 25 feet below grade. The soil in the borings consisted of silty sand and sand from surface to between 14 and 18 feet below grade, and clay and sandy clay from between 14 and 18 feet below grade to 25 feet below grade. Regional Groundwater Occurrence and Quality The site is located within the Eastern San Joaquin Subbasin of the San Joaquin Valley Groundwater Basin. The San Joaquin Valley comprises the southernmost portion of the Great Valley Geomorphic Province of California. The Great Valley is a broad structural trough bounded by the tilted block of the Sierra Nevada on the east and the complexly folded and faulted Coast Ranges on the west. The Eastern San Joaquin Subbasin is defined by the areal extent of unconsolidated to semiconsolidated sedimentary deposits that are bounded by the Mokelumne River on the north and northwest; San Joaquin River on the west; Stanislaus River on the south; and consolidated bedrock on the east. The Eastern San Joaquin Subbasin is bounded on the south, southwest, and west by the Modesto, Delta-Mendota, and Tracy Subbasins,respectively and on the northwest and north by the Solano, South American, and Cosumnes Subbasins. The Solano and South American are subbasins of the Sacramento Valley Groundwater Basin. The Eastern San Joaquin Subbasin is drained by the San Joaquin River and r Rincon Consultants 6