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The physical conditions at the site are described in detail in the following section: (1) The Forward site is located near the geographic center of the Great Valley of California. Original ground surface elevations at the site range from approximately 35 to 45 National Geodetic Vertical Datum (NGVD), sloping generally to the west. The Great Valley is an asymmetrical structural trough filled with a thick sequence of flat-lying marine and continental sediments. The surface soils are mainly composed of two soil types typical of Victor Formation sediments. The two soils, as mapped by the Soil Conservation Service, are known as Clear Lake clay (CL) and Jacktone clay (ST). These soils are similar in composition; they were formed from alluvium. The permeability of both these soils are low, the available water-holding capacity is moderate, the shrink-swell potential is high, and the water erosion potentials are low. The general water bearing characteristics of the surface soils, separated into clay, silt, and sand components are presented in Table 2.1. Typical uses of these soil types include irrigated cropland, orchards, vineyards, and sometimes irrigated pasture and urban development. Table 2.1 Regional Hydrogeologic Characteristics Permeability(k) Hydrogeologic Conductivity Specific Storage Porosity (n) Material cm2 (k) cm/sec (s) m.1 % Sand 10-1- 10-1 10-1- 10-4 10-1- 10-1 25 - 50 Slit 10-$- 10-12 10-1- 10-1 10-3- 10-4 35 - 50 Clay 10-12- 10-15 10-7- 10"10 10-2_ 10-4 40- 70 (2) The Forward site is located in the San Joaquin hydrologic basin. Based on groundwater elevation contours published by the San Joaquin County Flood Control and Water Conservation District, the regional groundwater in the vicinity of the site was -20 to -30 feet NGVD (approximately 60 to 70 feet below ground surface (gbs)) and appeared to be flowing north-northeast in Spring, 1990. The sediments have been divided into three large groups based on gross lithology and pervasive distinctions in color. Although several strata can be recognized in the logs, for purposes of this report they were grouped into the following three larger groups: Group Surface to approximately 28 to 40 feet; highly interbedded sandy silt, clayey silt, silt, and clay. A few layers of sand are present. Generally sands are fine grained. Most of the sediments have an oxidized appearance, showing an orange brown color. Group B Top - approximately 28 to 40 feet deep. Bottom - approximately 55 to 75 feet deep (25 to 35 feet thick); interbedded sand, silty sand, silt, and clay. Sands are fine grained. Overall, this layer is a little sandier than Group A. Sediments are distinctly less oxidized than Group A; showing a grey brown color. Forward Composting Facility RCSI 7/20/09;Page 19 SWT Engineering