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• the Magnitude 8+synthetic accelerogram generated by Seed and Idriss <br /> [1969] to simulate distant large-magnitude event on the San Andreas fault, <br /> scaled to 0.10 g to represent both the MCE and MPE. <br /> 3.5 SOILS <br /> 3.5.1 SURFACE SOILS <br /> The surface soils near the site are mainly comprised of two soil types typical of <br /> Victor Formation sediments. The two soils, as mapped by the U.S. Soil <br /> Conservation Service, are know n,as- Lake clay{CL) and Jacktone clay JSfl. <br /> These soils are similar in composition, being formed from alluvium. The Jacktone <br /> and Clear Lake clays are equally pervasive at the site with the Clear Lake clay more <br /> prevalent in the northern and southern portions of the site and the Jacktone Clay <br /> more prevalent through the middle portion. <br /> The Jacktone clay (ST) covers the nearly flat terrain 100 to 200 feet from the North <br /> and South Branches of the South Fork of Little Johns Creek. Typically, this soil type <br /> is found on O,.to.2 percent slopes fors mn,g.a.inoJd:erately..deep hardpan-of <br /> somewhat poorly drained soil made up of generally dark gray clay about 2 inches <br /> thick, underlain`by light gray clay loam;folowe'd b)tti-ardpan of 3 inches. <br /> Permeability is low, the available water capacity is moderate, the shrink-swell <br /> potential is high, water may be perched on top of the hardpan following heavy <br /> rain, runoff is slow, and the water erosion,hazard.js_.slight. The typical.auses..of:this <br /> soil type are irrigated cropland, orchards, vineyards, and sometimes irrigated <br /> pasture and urban development. <br /> The Clear Lake clay(CL) soil type is common along the North and South Branches <br /> of the South Fork of Little Johns Creek. The surface layer is dark gray clay about <br /> 29 inches thick followed by another 8 inches of dark gray clay, then 5 inches of <br /> mixed light brownish gray clay loam, then variegated dark grayish brown, weakly <br /> to strongly cemented hardpan to a depth of 60 inches. The permeability of this <br /> soil is low, available water capacity is moderate, the shrink-swell potential is high, <br /> water erosion hazard is low, and the soil is subject to rare flooding during <br /> abnormally high rainfall events. This soil type is typically used for irrigated <br /> cropland, orchards, and sometimes irrigated pasture and urban development. <br /> Forward Landfill JTD 3-7 <br /> L:\Allied\2000.193\Reports\Bnaljtd:Sec-3.0:08/20/01 <br /> BRYAN A.STIRRAT 6 ASSOCIATES <br />