Appendix E - Geology and Soils Geotechnical Supporting Information COMBINED

LESTER-SHRINER PROPERTY 132-8-2 Page 7 considered a hazard for fault surface rupture (see Section 4). Additionally, localized folding of the geologic units is apparent at a cut slope exposure and at our B-2 boring location within the Shriners parcel. Previously mapped small scale landslides (of Lowney, 1998) were also observed in our current site reconnaissance of the Lester Property and have led to our conclusion that these areas represent areas of rapid (seasonal) creep of the colluvial deposits rather than mobilized landslides (see Section 4). 3.3 SOIL AND BEDROCK CONDITIONS As discussed, the site is generally blanketed with residual soil and colluvium consisting of medium stiff to stiff lean to fat clay with varying amounts of sand and gravel. The 1998 Lowney investigation on the Lester parcel indicates the surficial colluvium was approximately ½ to 2 feet thick near the tops of ridges, and generally increased to approximately 5 to 11 feet thick within the saddles and localized drainage swales. More recently (2014) we conducted six test pits and two exploratory borings on the Shriners parcel. The test pits extended to depths ranging from 6.5 feet to 14 feet below the nearest adjacent ground surface. The borings extended to depths that ranged from approximately 25 feet to 31 feet. On the Shriner parcel, the surficial colluvium and residual soil ranged from approximately 1 to 6 feet thick on ridges and slopes, and increased to as much as 13 feet in drainage swales. At the northern edge of the Shriner parcel, the colluvium was approximately 6 feet thick and underlain by older alluvial soil consisting of very stiff sandy lean clay. Our explorations encountered the Tm unit (generally described as siliceous shale) within the northeastern portion of both parcels, and the Tmc unit (generally described as clay shale and siltstone) in the central portion of the Lester parcel and in the southwestern portion of the Shriners parcel. Previous Plasticity Index (PI) tests performed on two samples of these surficial clays at a depths ranging from 1 to 3 feet resulted in PI’s of 28 and 53, indicating moderate to very high plasticity and expansion potential. On the Lester parcel, the colluvium was reportedly (Lowney, 1998) underlain by bedrock which varied somewhat from the more general descriptions on the regional geologic map by Dibblee (1980, 2005). The bedrock consisted of interbedded sandstone, siltstone, and shale to the maximum depth previously explored at 18 feet. In general, the bedrock was reported by Lowney (1998) to be highly weathered, soft to moderately hard, friable, and intensely to moderately fractured. On the adjacent Shriner parcel, colluvium was also underlain by silty sandstone and claystone in the northeast portion and by interbedded sandstone, siltstone and minor claystone in the southwestern portion of the parcel. All of the bedrock units were weak in terms of rock strength, pervasively fractured with close spacing and severely weathered. Our exploratory borings conducted in 2014 within the western portion of the Shriner property included continuous dry coring in order to determine if a landslide existed in this area as mapped by Majmundar (1996). At these boring locations the bedrock (interbedded siltstone, sandstone and minor claystone) was typically thin bedded to laminated, weak in terms of rock strength and severely weathered. Drilling resistance increased steadily through the subsurface profile. Bedding orientations varied within the bedrock because of regional and localized folding in the area. This folding was also observed at a nearby cut exposure of siltstone. Dips ranged from moderate to the southwest to locally gently dipping toward the north. We did not encounter evidence of shearing or clay seams, soft zones or other evidence suggestive of landsliding. We Ii! CORNERSTONE EARTH GROUP