Site Characterization
The integration of the boring, CPT, and geophysical data allowed Fugro to develop a detailed model of the structure and characteristics of the subsurface underlying the proposed bridge. Soil and rock sequences were found to consist of:

• Shallow and outcropping bedrock on and near Yerba Buena Island at the western bridge abutment
• Thick sequences of marine sediments underlying most of the bridge alignment
  
• Extensive channeling within the marine sediments resulting in variable thicknesses of soft Bay Mud along the alignment
  
• Recent fill overlying the marine soil sequence on the Oakland Mole at the eastern bridge abutment.
  

Accurate characterization of the subsurface was crucial for design of the foundations and for analysis of seismic risk.