Workers at the Highway 99 tunnel site are building a plywood noise wall this week, so Seattle Tunnel Partners can get permission from the city to work at night.
STP will dig an 83-foot diameter, 120-foot deep circular pit to perform front-end repairs on the drill called Bertha, which has advanced only four feet since Dec. 6. The job will include full replacement of the main bearing, not just repair, according to Todd Trepanier, Highway 99 program administrator for the state Department of Transportation. Sand has penetrated past several rubber seals, and likely contributed to rapid overheating on Dec. 6-7 and Jan 28-29.
The wall will be half the height of the Alaskan Way Viaduct, and is being attached to Viaduct beams, from approximately South Jackson Street to South Main Street. It is meant to block noise from reaching Pioneer Square buildings, including low-income apartments next to the Viaduct.
Chris Dixon, STP’s project director, has previously said he would aim for a Sept. 1 restart, to continue drilling under the Viaduct toward South Lake Union. However, machine-builder Hitachi has yet to release its full repair plan, something state DOT said was expected by late March. In fact, Hitachi and STP held an initial high-level meeting just last week, so it’s reasonable to suspect that Dixon’s Sept. 1 goal will slip. Trepanier told reporters he hasn’t been notified of any change to the restart date.