1710 W MARINE VIEW DR Geotech Report 2023-12-29

TABLE 3. SOIL PROPERTIES IN SLOPE/W ANALYSIS Soil Unit Hydraulic Fill (Soft ML/Loose to Medium Dense SM)l Residual Unit Weigth Friction Angle Friction Angle (pcf) (deg) (deg) 120 28 3 Recent Deposits (Soft to Medium Stiff ML/Loose SM)l 125 28 5 Recent Deposits (Medium Dense SP)l 125 32 9 Glacially Consolidated Soils (Dense to Very Dense SP)l 130 39 - Riprap Rock2 125 45 - Notes: 'The soil properties for hydraulic fill, recent deposits, and glacially consolidated soils were estimated based on the correlations on SPTs. ?The soil properties for rip -rap rock were assumed. pcf = pound per cubic foot; deg = degree 4.3.1.3. Surcharge Loads Based on the collaboration with PND, the surcharge load within the building footprint is 190 pound per square foot (psf) in static condition and 115 psf in seismic and post -earthquake conditions. 4.3.1.4. Slope Stability Results Figures 6 through 8 present the slope stability analysis results for Cross Section A -A'. In static condition, the factor of safety (FOS) was evaluated generally over 3.0 for the slip surfaces going underneath the potential building footprints (Figure 6), which indicates a stable condition. In post -earthquake condition, most of the slip surfaces going underneath the potential building footprints have the FOS over 1.1 (Figure 7); while a small portion near the north edge of the building footprints that has slip surfaces with FOS around 1.0 may experience slope failure with excessive slope movement. In seismic condition (Figure 8), with a failure wedge starting from about one-third of the potential building footprints with a FOS of 1.0, the yield acceleration was estimated as 0.01g. The corresponding earthquake - induced lateral ground deformation was estimated at about 53 inches using the simplified displacement approach developed by Bray and Travasarou (2007) and Bray et al. (2018), which exceeds the allowable lateral displacement criterion of 18 inches per Table 12.13.2 of ASCE 7-16. Ground improvement is designed to reduce the lateral displacement to meet the allowable lateral displacement criterion per ASCE 7-16. Please note that the ground improvement does not mitigate the effects of liquefaction to the existing bulkhead, which is not part of our current scope of work. 5.0 GROUND IMPROVEMENT RECOMMENDATIONS Based on the collaboration with PND, we understand that due to the potential liquefaction issue at the site, ground improvement with rigid inclusion is selected as the foundation support for the buildings at PGL site to mitigate the ground deformations, that include static (long-term consolidation) and seismic (liquefaction - induced) settlements, earthquake -induced lateral ground deformation, etc., and prevent slope failure from occurring within the potential building footprints. GWENGINEERS� April 1, 2022 Page 6 File No. 06 i 6-030 00