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ENGEO INCORPORATED 5150.100.101 May 2, 2008 Page 4 As shown on Figure 5, the site is located within a preliminary State of California Seismic Hazard Zone for areas that may be susceptible to liquefaction. The slope located to the southwest of the property is mapped as an area that may be susceptible to seismically induced landsliding. Additional discussion regarding these potential seismic hazards is provided in the Conclusions section of this report. Other important active faults in the region include the Greenville fault located approximately 12 miles to the northeast of the site and the Hayward and San Andreas faults located 6½ and 26 miles, respectively to the southwest. 4.3 SUBSURFACE CONDITIONS We observed the drilling of 4 borings to depths ranging from 7 to 24 feet at the locations shown on the Site Plan, Figure 2. Shown on Figure 2 are depths to native rock and expected thickness of colluvial material from all known explorations conducted at the site. In general, the borings encountered medium stiff to very stiff, sandy silty clay to depths between 4 to 5 feet below existing grade along the eastern flat upper portion of the site. Beneath the clay, we observed friable, highly weathered siltstone, claystone and sandstone. At a depth of 20 feet in Boring 1-B1, strong, moderately weathered conglomerate was found. Our previous explorations at the site encountered similar conditions but also encountered colluvium in the western portion of the site. The colluvium encountered in our previous explorations varied in depth from approximately 9 feet to over 16 feet. Consult the Site Plan and boring logs for specific soil, rock, and groundwater conditions at each location. We include our boring logs in Appendix A. The logs contain the soil/rock type, color, consistency, and visual classification in general accordance with the Unified Soil Classification