Elliott Bay Seawall
Seattle’s seawall represents how incredibly transient and unstable the city’s landscape has been for the last two centuries.
In the late nineteenth century local land speculators and railway companies filled in most of Seattle’s tidelands in order to make landed property. The “reclaimed” tidelands, however, were unstable. People could build on them, but as the fill—anything from boulders to rubble from the Great Fire of 1889—settled and subsided, sewer lines and water pipes could be damaged, and railway tracks and trestles on the surface could warp. In 1901, the White Star Line dock fell into Elliott Bay. So, instead of building on unstable ground, railroad companies began constructing tracks on a trestle system that extended out over Elliott Bay. The trestle system, however, came with its own set of dangers, and the city concluded that it needed a seawall.[1]
In 1916, the city built a twenty-foot-tall concrete seawall, backfilled with dirt, between Washington and Madison Streets. Eighteen years later, Seattle finally had a complete seawall built with corrugated steel sheet piling, a wood platform, concrete slabs, and wood piles. Over time, saltwater corroded holes in the steel of the seawall and gave marine wood-boring creatures called gribbles access to the wall’s supporting timbers. During the 2001 Nisqually earthquake, the raised freeway beside the waterfront settled several inches. When engineers dug below the platform to investigate, they discovered that some of the supporting sections were entirely gone due to gribble damage. Another earthquake could cause the viaduct and seawall to collapse into the bay.[2]
In 2017, the City of Seattle is set to complete its new seawall. Concrete and steel make up the construction of this new wall and the decaying supporting timbers have been eliminated, but, like the old seawall, this one will still allow water to percolate through—freshwater from Seattle’s hills and salt water from the bay. The new seawall fits current seismic standards and is expected to last at least 75 years.[3]
[1] Matthew Klingle, Emerald City: An Environmental History of Seattle (New Haven: Yale University Press, 2007), 53-57, 61, 77; David B. Williams, Too High And Too Steep: Reshaping Seattle’s Topography (Seattle: University of Washington Press, 2015), 86-89.
[2] Williams, Too High And Too Steep, 90; John Roach, "Seattle Waterfront Falling to Gribble Invasion," National Geographic News, last modified April 23, 2004, accessed August 20, 2016, http://news.nationalgeographic.com/news/2004/04/0423_040423_gribbles.html.
[3] Williams, Too High and Too Steep, 49-50; City of Seattle, “Seawall Project Basics,” Waterfront, n.d., accessed August 20, 2016, http://www.waterfrontseattle.org/seawall.
Credits and Sources:
Description by Madison Heslop on behalf of the American Society for Environmental History.
City of Seattle. “Seawall Project Basics.” Waterfront. n.d. Accessed August 20, 2016. http://www.waterfrontseattle.org/seawall.
Klingle, Matthew. Emerald City: An Environmental History of Seattle. New Haven: Yale University Press, 2007.
Roach, John. "Seattle Waterfront Falling to Gribble Invasion." National Geographic News. Last modified April 23, 2004. Accessed August 20, 2016. http://news.nationalgeographic.com/news/2004/04/0423_040423_gribbles.html.
Williams, David B. Too High and Too Steep: Reshaping Seattle’s Topography. Seattle: University of Washington Press, 2015.
