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Project No. JB-569 20 June 2006 Revised 18 October 2006 Page 4 4.2 Geology Based on our review of geologic maps (Dibblee, 1980; Garlock, 1988; Warner, 1991; Helley and Graymer, 1997) the site appears to be underlain by Plio- Pleistocene non-marine deposits (Livermore Gravel) as shown in Figure 8, Geologic Map. The Livermore gravel is described as reddish-gray cobble-pebble gravel containing debris from Franciscan rocks and moderately brown, poorly cemented, well-imbricated, clast supported, planar-bedded gravel, with interlayered sandstone and siltstone. 4.3 Geotechnical Hazards Risk of geotechnical hazards will always exist due to uncertainties of geologic conditions and the unpredictability of seismic activity in the area. However, in our opinion, based on available data, there are no indications of geotechnical hazards that would preclude use of the site for the proposed development. The proposed structures should be designed to meet current Uniform Bui/ding Code (UGC) requirements to limit potential damage from ground shaking. 4.3.1 Liquefaction It is our opinion, based on our review of hazard maps (Knudsen, 2000), the soil conditions encountered, and laboratory testing, that the site soils encountered have a low potential of soil liquefaction. 4.3.2 Landslides Review of landslide hazard maps (Majmundar, 1991, Roberts, 1999) do not indicate that any landslides have been mapped on the site. The site is mapped within an area designated as "Least Susceptible Area" for landslides (Majmundar, 19911 Native slopes on the site are generally mild (3H:1 V or less). The fill slopes north of the existing residence and in the northwest corner of the site appear to be over-steepened. These areas should be graded in accordance with our recommendations provided in this report. The slope immediately south of Lot 1 is the backyard for an adjacent residence. The slope is mild (approximately 4H:1 V) and has a 10 to 1 5-foot bench with a concrete drainage ditch at the property boundary. Based on our review of geologic hazard maps and our site observations, it is our opinion that the site has a low potential for landslides. Some minor sloughing may be expected as soils are saturated during the winter months. ~orbmacher Engineering, Inc.