Geotechnical Challenges Associated with the Design of a New Marine Oil Terminal at the Port of Los Angeles

The Port of Los Angeles (POLA) commissioned a project to design and construct a deep-water Crude Oil Marine Terminal (COMT) to accommodate large and small oil tankers and barges. The proposed COMT will be the first deep-water oil terminal to be constructed in California since 1984. The marine structures were designed according to the Chapter 31F of the 2007 California Building Code (CBC 2007), otherwise known as MOTEMS (Marine Oil Terminal Engineering and Maintenance Standards). The project is located in a high seismic region. MOTEMS requires a two- level seismic design with corresponding performance criteria. In addition, the structures were also checked for the CBC 2007 building ground motion criteria. The subsurface materials were found to consist primarily of elastic silt with some clay and sand and also strong but localized thin layers of rock that were encountered at random depths. Several site factors, including the presence and randomness of the hard rock layers and deep waters at the proposed structure locations limited the potential foundation types that were considered suitable for the project. The design of foundations for various structures was further challenged by the high breasting, berthing, and mooring loads from the oil tankers and high seismic loads on the foundations for the unloading platform and trestles. Among the various foundation types evaluated, large-diameter steel pipe piles were considered the most preferred foundation option based on the cost and constructability. This paper addresses the geotechnical challenges associated with the project and measures that were taken to overcome these challenges during development of the project.