The 57.5-foot tunneling machine that begins its journey from Pioneer Square to South Lake Union this summer, is presently cradled in an 80-foot launch pit, poised to delve underground.
In the prelude to the start of boring, workers are shoring up soils in the Pioneer Square area, making sure that all the supports, hoses and electrical connections are in working order, and stock-piling giant concave slabs that will eventually become the walls the tunnel. When Bertha emerges from the tunnel’s 1.7 mile route, the machine will have excavated 800,000 cubic yards of soil, but will also have placed the infrastructure of the tunnel itself.
Consider, people, what we’re talking about here. Eight-hundred-thousand cubic yards of soil! How much is that? Well, if you were to pile it on top of the turf at CenturyLink Field–and who, pray tell, would do that?–it would be about 380 feet tall, more than 100 feet taller than the stadium’s roof.
That giant pile-up, of course, isn’t happening. Instead, disposal will be helped along by a giant conveyor belt that extends from the tunnel to barges waiting at Terminal 46. The barges will take the soil across Puget Sound to a reclamation site near Port Ludlow. There, the nice clean Seattle soil will be used to fill in and restore the old Mats Mats rock quarry. Definitely a win-win solution.
Overall, the massive engineering project is nothing short of miraculous to lay folks like me. How can the various contractors and subcontractors, abetted and supervised by multiple government levels, engineers and technicians, coordinate hundreds of workers and their myriad tasks and produce a wonder that, thus far, appears to be on schedule?
We’re not building the Great Pyramids. But, given the details, it seems as if we’re rivaling the Seven Wonders of the World with our largest ever tunnel project. Historic footnotes, anyone?