Sometime this summer, the world’s largest tunnel boring machine, aka Bertha, will begin drilling a two-mile-long hole under Seattle’s downtown waterfront for the State Route 99 Alaskan Way Viaduct replacement. Grinding along at about 30 feet a day, Bertha will displace approximately 900,000 cubic yards (1.8 million tons) of dirt, or as it is more technically known, “muck.”
It’s hard to visualize this quantity of dirt. Try this: Dumped into West Seattle’s Colman Pool it would reach almost to the height of two Columbia Centers stacked one on the other. The real plan for the displaced dirt is to move it by conveyor belt to Terminal 46, to be loaded onto barges and transported to the old Mats Mats quarry in Port Ludlow on the Olympic Peninsula, where it will be used as part of a reclamation project on the site. It’s a practical plan, if perhaps a little less than visionary. Remembering Seattle architect Jerry Garcia’s brilliant idea for restoring the pre-regrade Denny Park (which he first put forth in 2006), we asked a few smart locals what they might do with this enormous pile of loam.
When inviting these creative soil solutions, we suspended questions of budgets and Seattle process, as well as legitimate concerns about toxins and metals in the soil. It should also be noted that our imagineers are not in any way endorsing the tunnel as the best option for replacing the Viaduct—as is evident in one or two cases. Some folks still hold “the surface option” in their hearts.
See what the students at Arbor Heights Elementary School and Adams Elementary planned to do with all the leftover dirt. Read David B. Williams essay on Seattle’s long-term obsession with ambitious earth moving projects.