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July 13,2001 <br /> Job Number: LGO1-191 <br /> Page 5 <br /> VI. GEOLOGY, SOILS,AND PERCOLATION TEST <br /> ` The surface geology at the site is shown on Atwater's map and is composed of the <br /> Holocene and(or)upper Pleistocene age alluvium designated as Holocene alluvium of supratidal <br /> flood plains(undivided)' (Plate 2). The alluvium of the flood plains contains clay, silt and sand <br /> mixtures. <br /> The soils on the site are reported to be the Scribner-Urban land complex (no. 245) (Plate <br /> ` 3).3 The San Joaquin Soil Survey describes the soil as the following: "This nearly level map unit <br /> is on flood plains. Elevation is near sea level to ten feet above. This unit is 50 percent Scribner <br /> clay loam and 35 percent Urban land. The Scribner soil is very deep and poorly drained. It <br /> formed in alluvium derived from mixed rock sources. Mottles in the profile indicate a poorly <br /> drained soil; however, drainage has been improved by levees and reclamation projects. <br /> Permeability is moderately slow in the Scribner soil. Available water capacity is very high. <br /> Urban land consists of areas covered by roads,driveways, sidewalks,parking lots,buildings, and <br /> other structures. The soil material under the impervious surface is similar to that of Scribner clay <br /> loam." Table 4 presents some selected properties of the Scribner-Urban land complex soil. <br /> Table 4. <br /> Selected Soil Properties of the Scribner-Urban Land Complex. <br /> San Joaquin County Soil Survey Reports <br /> Soil Name and Depth(in) Unified Soil Salinity Soil Septic tank <br /> Map Symbol Classification mmhos/cm Reaction absorption <br /> pH fields <br /> Scribner-Urban land 0-20:Clay loam. CL <2 6.1-7.8 Severe: <br /> complex,0 to 2 20-60: Stratified loam to CL <2 6.6-8.4 wetness,peres <br /> percent slopes,245. silty clay loam. I I I I slowly. <br /> Note: The table descriptions do not necessarily reflect site-specific soil properties. <br /> A total of four(4) soil borings was drilled on parcel to characterize the subsurface <br /> conditions and measure the percolation rate of the soil. Plate 1 identifies the locations where the <br /> 'Atwater,B.F., 1982,Geologic Maps of the Sacramento-San Joaquin Delta,California:U.S.Geologic <br /> Survey Miscellaneous Field Survey Map MF-1401,21 Sheets,Scale 1:24,000. <br /> 3 USDA Soil Conservation Service,Soil Survey of San Joaquin County,California, Sheet 12. <br /> =pERfp1 <br /> �+s o c• <br /> r.. <br />