1400 W MARINE VIEW DR WATERFRONT PLACE APARTMENTS Geotech Report 2022-10-25

TABLE 1.2015 IBC SEISMIC DESIGN PARAMETERS • IBC Parameter Recommended Value Site Class E Short Period Spectral Response Acceleration, Ss(g) 1.30 1-Second Period Spectral Response Acceleration,Si(g) 0.492 Seismic Coefficient, FA 0.9 Seismic Coefficient, Fv 2.4 Corrected Peak Ground Acceleration)(PGA)(g) 0.494 Design Earthquake Magnitude2(M) 6.61 Notes: 1 Given that the building period is less than 1/2 second and the average blowcount is less than 15,the PGA can be corrected for Site Class E per ASCE 7-10 Section 11.8.3.A factor of 0.9 was applied to the unfactored PGA of 0.549g to give a corrected PGA of 0.494g. 2.Given the lateral spreading hazard,the modal maximum magnitude was used in our liquefaction and lateral spreading analyses. For our liquefaction and lateral spreading analyses, we considered an earthquake magnitude (M) of 6.61 and a peak ground acceleration (PGA) of 0.494g. Given the lateral spreading hazard, which is dependent on site to source distance, the modal maximum seismic event was selected as the preferred design earthquake. The site to source distance for the modal maximum earthquake represents a distance to a known fault, compared to the mean maximum earthquake which averages the site to source distances and does not represent the distance to a known fault. Ground Improvement The very loose to loose fill and recent deposits below the groundwater elevation are susceptible to liquefaction. The liquefaction hazard presents a liquefaction-induced (seismic) settlement and lateral spreading risk.The project team has elected to mitigate seismic settlement and lateral spreading by means of ground improvement. Interbedded layers of soft silt and clay within the fill are prone to static settlement. Static settlement will be mitigated with the ground improvement.The proposed buildings may be supported on shallow foundations bearing on improved ground. The ground improvement will be designed by Advanced Geosolutions, Inc. We understand that the ground improvement will consist of cement deep soil mixing(CDSM)columns below building slab and foundations. We also understand that the ground improvement design will include a CDSM buttress to mitigate lateral spreading. The CDSM buttress will consist of shear panels with a front closure CDSM wall. Replacement ratio, spacing and diameter should be determined by the ground improvement contractor who should develop a performance-based design that will meet the performance criteria presented in the following section. We recommend that GeoEngineers be retained to review the proposed ground improvement program and observe the installation of the selected ground improvement method. Performance Criteria Ground improvement should be designed to meet the following performance criteria for static and seismic settlement, lateral spreading and allowable bearing pressure: a 1 inch of static settlement • GEOENGINEERS May 31,2017 Page 6 File No.22360-003-00