Seismic Screening and Requalification of Marine Oil Terminals in California

There is an infrastructure of marine oil terminals in California, with an average age of over 50 years. Historically, there has been no consideration for the increased seismic risk and the possibility of massive amounts of oil to be spilled in California's ports or in San Francisco Bay. Most of these structures were built with little or no consideration for seismic loading and the current state of repair is generally poor. Additionally, the petroleum pipelines have never been analyzed for the displacement motion associated with the seismic demand. As these structures were inspected above the water line for many years by the California State Lands Commission (CSLC), operators/owners were in no rush to make any improvements. As a result of the 1994 Northridge Earthquake, a federal hazard mitigation grant was given to the CSLC to develop standards to mitigate future damage to port/harbor pile-supported structures. The code was completed in 2006, and is primarily for marine oil terminals, but is generally applicable to port/harbor pile supported wharves or piers. This new set of standards is Section 31F of the California Building Code and is now enforceable. An initial group of 10 "high risk" terminals have submitted their initial audits, documenting the structural condition, above and below the water line, along with plans for seismic rehabilitation. A fitness-for-purpose criterion not only provides inspection results, but also provides a structural assessment, as to whether or not the facility will meet the performance standard of two levels of seismic demand. These initial 10 terminals are in high seismic zones, and the seismic demand for a Level 1 earthquake is 50% probability of excedance in 50 years, and for a Level 2, the standard is a 10% probability of excedance in 50 years. This paper will provide summary results of some of these terminals, providing a general description of how they were modified to meet the seismic criteria, with minimum down-time.