PLENARY SESSION 2: Transforming the Seattle Waterfront-PPT Presentation

PPT Presentation

Pdf Summary

Seattle’s waterfront has been repeatedly reshaped by natural forces and human engineering. Its geology reflects tectonics, earthquakes, glaciers, volcanoes, rivers, lakes, and deltas. In the late 19th and early 20th centuries, Seattle regraded its terrain, created new land, and built a seawall. A waterfront viaduct followed in the mid-20th century.<br /><br />These projects left complex subsurface conditions, including loose fill, debris, buried timber, variable soils, and high groundwater. Liquefaction and lateral spreading posed significant earthquake risks. From 2000 to 2018, the city replaced the seawall, built a two-mile, 57.5-foot-diameter SR 99 bored tunnel, and demolished the viaduct. Tunnel construction encountered mixed and challenging ground, including abrasive and sticky soils and running sands.<br /><br />The seawall project aimed to improve seismic safety while protecting cultural and historic resources, enhancing habitat, limiting construction impacts, supporting the waterfront economy, and enabling future public spaces. Since 2018, the focus has shifted to revitalizing the waterfront, including projects such as Elliott Way and Overlook Walk. The presentation emphasizes how understanding Seattle’s past geology and infrastructure helps inform planning and construction for its future.

Keywords

Seattle waterfront

geology

seismic safety

liquefaction

lateral spreading

seawall replacement

SR 99 tunnel

waterfront viaduct

groundwater

urban redevelopment