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i October 4,2002 NOA ENVIRONMENTAL PROJECT NUMBER:LEOO-429 by east-lipping Cretaceous'and Cenozoic,strata that form deeply buried synclinal' trough, lying beneath the Great Valley along its western side " ' General Soil Information ' The subject parcel is generally located on soils identified as Jacktone-Urban land complex, 0 to 2 percent slopes by the US Department of Agriculture(USDA), Soil Conservation Service, Soil Surv� of San Joaquin County, California (1992) The following is an excerpted description of these soil 1 units by the USDA Soil Conservation Service "This nearly level soil unit is in basins Elevation 10 to 40 feet The average annual ' precipitation is about 14 inches, the average annual air temperature is about 60 degrees F, and the average frost-free period is about 270 days ' This unit is 50 percent Jacktone clay and 35 percent Urban land The components of this unit occur as areas so intricately intermingled that it was not practical to map ' them separately at the scale used The Jacktone soil is moderately deep to a hardpan and is somewhat poorly drained It formed in alluvium derived from mixed rock sources Mottles in the profile indicate a somewhat poorly drained soil, however, drainage has been improved by levees and reclamation projects Typically, the surface layer is very dark gray and darkgray clay about 22 inches thick The upper 12 inches of the subsoil is dark gray clay and light gray clay loam The next 3 inches is a light gray, strongly cemented to indurated hardpan The next 9 inches is yellowish brown loam The lower part to a depth of 60 inches is a yellowish brown, weakly cemented hardpan In some areas the surface layer is silty clay or silty clay loam ' Permeability is slow in the Jacktone soil Available water capacity is moderate The shrink-swell potential is high The effective rooting depth is limited by the hardpan at a depth of 20 to 40 inches Depth to the water table is more than 5 feet, but water ' may be briefly perched above the hardpan after periods of heavy rainfall or irrigation Runoff is slow, and the hazard of water erosion is slight The rate of water intake in irrigated areas is 0 1 inch per hour The soil is subject to rare About 65 to 136 nultion years ago z About 0 to 65 nulhon years ago ' 3 V-shaped ' 7