While WSDOT says they’re not saying this is the only thing that stopped the tunnel-boring machine four weeks ago – they’ve gone public this afternoon with a discovery. No, not a huge boulder, or train car, or UFO, or whatever your favorite guess might have been. According to this brand-new update, they have found a pipe that was submerged by WSDOT itself more than a decade ago. From the update:
On Jan. 2, the water pressure was low enough and enough soil was removed from the excavation chamber to inspect the top 15 feet of the chamber.
This inspection showed an 8-inch-diameter steel pipe protruding through one of the many openings in the cutterhead. We believe the steel pipe is a well casing installed by WSDOT in 2002 after the 2001 Nisqually earthquake to better understand how groundwater flows through this area. The location of this pipe was included in reference materials in the contract.
We also believe at least some of the obstructions found by the exploratory holes are pieces of the 2002 steel pipe, which could be a contributing factor in the delay of boring.
So while the tunneling contractor and WSDOT are taking pains to say this might not be the ENTIRE problem, they are also figuring out now how to remove that pipe for starters. As the full update says, they don’t know yet what this means to the schedule, which had projected tunnel completion by the end of 2015 and Alaskan Way Viaduct teardown starting after the tunnel opened.