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

the geotechnical engineer during final design development to evaluate suitable cut slope inclinations for • the various portions of the excavation. The above guidelines assume that surface loads such as traffic, construction equipment, stockpiles or building supplies will be kept away from the top of the cut slopes a sufficient distance so that the stability of the excavation is not affected. We recommend that this distance be at least 5 feet from the top of the cut for temporary cuts made at 11 H:1V or flatter. Temporary cut slopes should be planned such that they do not encroach on a 1H:1V influence line projected down from the edges of nearby or planned foundation elements. Water entering excavations must be collected and routed away from prepared subgrade areas. We expect that this may be accomplished by installing a system of drainage ditches and sumps along the toe of the cut slopes. Some sloughing and raveling of the cut slopes should be expected. Temporary covering, such as heavy plastic sheeting with appropriate ballast, should be used to protect these slopes during periods of wet weather. Surface water runoff from above cut slopes should be prevented from flowing over the slope face by using berms,drainage ditches,swales or other appropriate methods. If temporary cut slopes experience excessive sloughing or raveling during construction, it may become necessary to modify the cut slopes to maintain safe working conditions.Slopes experiencing problems can be flattened, regraded to add intermediate slope benches, or additional dewatering can be provided if the poor slope performance is related to groundwater seepage. Earthwork and Structural Fill • Based on the subsurface soil conditions encountered in the explorations, we expect the soils at the site may be excavated using conventional heavy-duty construction equipment. We anticipate that excavation work will be completed within the fill soils,which generally consist of very loose to loose sand with variable silt and gravel content and wood debris. Wood debris,ranging in size and consistency from sawdust to timber logs, were encountered to depths of up to 261/2 feet. Interbedded soft silt layers were also encountered within the fill.Shell fragments were also consistently encountered throughout the fill between approximately 5 and 25 feet below existing site grades. We understand that the shell fragments are likely a result of dredging that was completed during construction of the port.Additionally,the contractor should be prepared for occasional cobbles and boulders in the site soils. Likewise, the surficial fill may contain foundation elements and/or utilities from previous site development, debris, rubble and/or cobbles and boulders. The on-site soils contain significant fines (material passing the U.S. Standard No. 200 sieve) and will be highly moisture-sensitive and susceptible to disturbance, especially when wet. Ideally,earthwork should be undertaken during extended periods of dry weather when the surficial soils will be less susceptible to disturbance and provide better support for construction equipment. Trafficability on portions of the site may be difficult, even during dry weather conditions, due to the wet soft/loose fill soils.The contractor should be prepared to protect the site and prevent subgrade soils from deteriorating due to construction traffic and wet weather conditions. • GEOENGINEERS� May31,2017 Page 12 He No.22360-003-00