Seattle tunnel builders make progress in repair

AP News
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Posted: Sep 08, 2014 6:01 PM

SEATTLE (AP) — Bertha, the broken-down tunneling machine, moved forward three feet during recent testing, while workers building an underground circular pit that will allow access to the machine finished installing the last of 84 large concrete cylinders known as piles.

Workers installed the final 11 piles last week, and they will begin to fill in gaps between the piles and move to the next stage of the repair work, said Laura Newborn, a spokeswoman for the Alaskan Way Viaduct replacement-tunnel project. The workers are building an 83-foot-wide underground pit that will support a large crane designed to pull Bertha out of the ground so it can be fixed.

Work on the 2-mile tunnel that will move State Route 99 underground stalled in December after Bertha hit a pipe and quit working.

Later this week, crews will start drilling wells that will let in groundwater to help move the tunneling machine into the pit. They expect to finish work on the wells by mid-September so the excavation of the pit can start, Newborn said.

When Bertha moved during that testing, it allowed workers to evaluate the machine's systems and positioned it closer to the exterior wall of the pit, Newborn said.

Seattle Tunnel Partners expects to resume drilling on the tunnel in March 2015. The breakdown set the project back about a year. The tunnel is expected to be completed in November 2016, Seattle Tunnel Partners has told the Washington Department of Transportation.