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December 18,2001 <br /> _ Job Number:LGO1-375 <br /> Page 6 <br /> VI. GEOLOGY, SOILS, AND PERCOLATION TEST <br /> The surface geology at the site is shown on Marchand and Atwater's maps that is <br /> composed of the Holocene and (or) upper Pleistocene age alluvium of middle and upper <br /> members of the Riverbank Formation (Plate 6). The Riverbank Formation consists of alluvial <br /> sand, silt, and other material. The material is essentially volcanic detritus and glacial outwash <br /> from the Sierra Nevada mountains and foothill terrain. <br /> The surface and near surface soils located across the site are reported to be San Joaquin <br /> Complex (no 241)(Plate 7)6. The San Joaquin Series Soil is described as "...composed of 45 <br /> percent San Joaquin loam and 40 percent San Joaquin loam, thick sequence. The components of <br /> this unit occur in areas so intricately intermingled and was not practical to map (by USDA) them <br /> separately at the scale used. Permeability is very slow in the San Joaquin soil that does not have <br /> a thick surface layer. The shrink-swell potential is high. Water is briefly perched above the <br /> claypan and hardpan after periods of heavy rain or irrigation." Table 3 presents some selected <br /> properties of the San Joaquin Series Soils. <br /> Table 3. <br /> Selected Soil Properties of the San Joaquin Series Soil. <br /> San Joaquin County Soil Survey Report." <br /> Soil Name and Map Depth(in) Unified Soil Salinity Soil Septic tank <br /> Symbol Classification mmhos/cm Reaction absorption <br /> PH fields <br /> San Joaquin 0-16: Loam. CL-ML,ML <2 5.6-6.5 Severe: <br /> Complex,241. 16-26: Clay loam,clay. CL <2 6.1-7.8 cemented pan, <br /> 26-60: Indurated. — — — peres slowly. <br /> Note: The table descriptions do not necessarily reflect site-specific soil properties. <br /> 5 Marchand,D.E.,and Atwater,B.F. 1979,Preliminary geologic map showing Quaternary deposits of the <br /> .� Lodi Quadrangle,California: U.S.Geologic Survey Open File Report OFR 79-933,Scale 1:62,500. <br /> 6 USDA Soil Conservation Service,Soil Survey of San Joaquin County,California, Sheet 6. <br /> rpERiO <br /> r ti <br /> 1 + <br /> Z � <br /> O � <br /> ♦ssoc� <br /> r <br />