Summer 2000
SEA GUARD Marine Fenders Provide Design Example at U.S. Coast Guard Pier 37 in Seattle
“The system had to be able to berth the 12,100-ton icebreaker but also had to berth other vessels as well.”
Arnfinn Rusten
Senior Project Manager for BERGER/ABAM
Situated on Washington’s Puget Sound, Seattle is home to the U.S. Coast Guard’s WAGB Ice Breaker and the site of one of the finest applications of Seaward’s SEA GUARD marine fenders to date. The American Construction Company, under contract with the U.S. Coast Guard (USCG), demolished and reconstructed Pier 37 at the USCG Support Center in Seattle. The existing wooden pier was replaced with a concrete structure using both precast members and cast-in-place concrete construction, protected by a fender system with fifteen 5-foot (1.52m) diameter by 10-foot (3.05m) length Seaward SEA GUARD fenders at the center of the design.
Although Puget Sound is protected from the Pacific Ocean by the Olympic Mountains, it experiences tidal fluctuations of up to 18 feet (5.5m). Fendering in this difficult environment required a design that would allow the fender to adjust automatically to the tidal movements. Fortunately, BERGER/ABAM Engineers, Inc., of Federal Way, Washington, found the solution. By mounting the SEA GUARD fenders in front of concrete fender piles with the ends of the fender chains connected to guide piles, the floating SEA GUARDS would be free to adjust vertically with the tide while locked into their horizontal position. Another feature of the design was the utilization of UHMW plastic sheets mounted to the face of the fender piles to protect the skin of the fender from excess abrasion and daily movements of the fender with the tide.
“The unique aspect about the project was the challenge to berth an icebreaker and provide fendering for a vessel with an egg-shaped hull,” says Arnfinn Rusten, senior project manager for BERGER/ABAM. “The 399 ft. (121.6m) hull is designed to handle ice travel but makes it difficult for a fender system to satisfy standoff requirements and still provide spacing for economy. The system had to be able to berth the 12,100-ton icebreaker but also had to berth other vessels as well. We did an extensive study on attaining optimum layout for economy while protecting the structure and vessel and found the SEA GUARD fender and pile system to be the best for this application. All that we hear about the project is good, and others often refer to it as a design example. BERGER/ABAM is very proud of the project.”
With the new design and demolition complete, construction on the new pier began by driving 20-inch octagonal piles vertically and on a batter and then casting pile caps to support the haunched precast decking panels. Concrete fender piles to back the SEA GUARD fenders were then driven into place and the final concrete wear surface applied. Final fit-up of the fender piles included mounting a vertical pipe section on the side of the two outward piles in each fender pile section. These vertical pipe sections served as the guide for the slip ring to which the SEA GUARD fender mounting chains connected. When the project was completed, American Construction project manager, Kevin Culbert commented that it was well designed and went together as planned.
Seaward fenders were selected for this job because of their quality, Seaward’s willingness to provide an extended warranty, and the fenders’ ability to meet the performance criteria: to absorb 180,000 foot-pounds (244 kN-m) of energy, plus the ability to withstand a sustained reaction force of 125,000 pounds (556 kN) for a duration of 24 hours for at least 200 occurrences during the fender life. The USCG specifications referenced nine ASTM specification sections governing the construction and testing of the fenders for galvanizing of steel, tension and tear properties of the foam and rubber components, and abrasion resistance.
To learn more about SEA GUARD fenders, please contact Seaward.