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The popular fishing port of Crescent City is located in the area of the West Coast most vulnerable to tsunamis. The occurence of two tsunamis in 2006 and 2011 caused about 40 million dollars worth of damage to the waterfront structures. This emphasises the importance of including tsunami resistance in the design of the marina. Today the tsunami resistant marina is at the forefront of resilient design.
COWI was retained to design a more resilient marina with the requirement for a 50-year tsunami recurrence interval design life. The service life of a marina is generally 25-years. Robustness, resiliency and redundancy were key attributes of the dock system. The development of an original design for a more resilient Crescent City Marina was based on a rational approach as when the design for the new harbor was underway, prescribed tsunami standards did not exist. This work was the first of its kind.
With no established design criteria for tsunamis COWI provided the Harbor District with an extensive hydrodynamic model analysis method to develop a cost-effective, resilient design.
Several layouts were reviewed for berth sizes, distribution, sizing, and fairway requirements. The alternative layouts included critical details for floats, fingers, walkways, attenuators and associated electrical, potable water, and firewater requirements. Development of construction cost estimates of the alternatives assisted the Harbor District’s review and selection. This information was used to procure funding for the selected layout. The multi-use conditions of the marina required careful consideration and planning to minimize construction costs. Assistance was provided to the District with public presentations to further project design decisions and awareness.
A crucial aspect of the project was the phasing of construction works to cause minimal disruption to the local fishermen. COWI provided the detailed planning, structural and coastal engineering design. The work included the layout of floats and finger piers, structural analysis and design of the new concrete floats, walkways, attenuators, accessible gangways, and landings, location of access ramps and access points compliant with the Americans with Disabilities Act, as well as design of rock-socketed pilings, floats, and wave attenuators. The design loads include dead, live, wind, wave, impact, and tsunami conditions.
Jørgen JuhlProject & Market Director, Marine & Foundation EngineeringTel.: +45 5640 1178
John ChapmanVice President, Business Development, COWI Marine North AmericaTel.: +1 203.400.6540
Roger KeelingManaging Director UAE+971 (0) 50 452 1296
Mogens HviidRegional Manager, Marine Management+65 85 880 800