Seattle — The first phase of Seattle’s waterfront rejuvenation — the $410 million, 3,700-foot-long seawall replacement project — received a top award at the American Council of Engineering Companies’ Engineering Excellence Awards Gala held on April 25, 2017, in Washington, D.C. The seawall entry won a Grand Award in the “Environmental” category in recognition of its innovative salmon-friendly design by Seattle engineering firm Magnusson Klemencic Associates (MKA).
Seattle’s 75-year-old seawall was at risk of collapse, battered by tidal forces, subject to underground marine borers, and shaken by past earthquakes. Failure was possible in the next seismic event, due in part to surrounding liquefiable soils. The City of Seattle Department of Transportation established the Elliott Bay Seawall Project to replace the aging wall both for seismic reasons, and to restore a long-interrupted historic migration corridor for endangered Chinook salmon along the downtown waterfront, as identified in the 2007 Puget Sound Salmon Recovery Plan. Years of overwater development along the waterfront had created an environment of shadows and deep canyons not conducive to salmon migration, and restoration goals were established as: shallower intertidal water depths, improved lighting, and increased marine food and shelter.
The City of Seattle Department of Transportation hired Parsons to complete an existing 30% seawall replacement design (developed by a previous team). MKA served as Parson’s “Public Realm Lead,” responsible for design integration of all project habitat and public space components.
MKA’s design was recognized by ACEC for a number of innovations, including the concept of stacking the pedestrian promenade public space over the salmon migration corridor by siting the new seawall face 15 feet landward of its old location. MKA also performed complex daylight modeling and analysis of a custom light-penetrating sidewalk (LPS) solution, provided design oversight of the LPS panels and of artistically textured face panels and habitat shelves fronting the new seawall to offer food and protection, and designed other key public space components, including a unique movement joint plate between the sidewalk and the piers, a custom vehicle-rated railing, pedestrian benches, and steel riparian planters.
Seattle’s new, state-of-the-art, seismically resistant seawall is seamlessly integrated with a first-ever salmon migration corridor and an enhanced tidal marine environment, greatly benefitting the citizens, businesses, and visitors of Seattle and the native salmon and other creatures of the sea.
ACEC’s annual Engineering Excellence Awards program honors the year’s most outstanding designs by U.S. engineering firms across 12 judging categories.