Treasure Island, California
ENGEO provided a geotechnical review and provided on-going engineering consultation with respect to reuse for future development on the previous 330-acre Naval Base sites. Improvements will include as many as 5,500 housing units, two hotels, a conference center and a commercial district near a proposed ferry terminal sliced into the west side of the island. There also will be five residential towers near the ferry. All essential development will be within walking distance, including a ferry straight to downtown San Francisco.
Significant site geotechnical hazards and risks exist on these islands include extensively widespread and deep deposits of loose “man-made” fills (up to 45 feet thick) considered liquefiable when subject to strong ground shaking; thick natural deposits of soft, highly compressible Young Bay Mud deposits (over 100 feet) considered susceptible to large settlements with new loads; slope stability and seismic deformation of large marine landslides along dikes along the perimeter of Treasure Island; and the presence of shallow ground water.
ENGEO has provided preliminary consultation with regard to various mitigation approaches, foundations and redevelopment strategies including comparative cost versus risk analyses for low density and high density development alternatives, mainline utilities and arterial streets, and perimeter stabilization methods for marine landslide and dike failure areas.