Jan. 27 update: Restart of tunneling machine begins this week; evaluation will follow initial mining

Posted on Jan 27 2014 6:40 PM

Seattle Tunnel Partners is expecting to restart operations of the SR 99 tunneling machine this week.

Crews will finish inspections of the excavation chamber and cutterhead by the morning of Tuesday, Jan. 28. This will mark the completion of the hyperbaric intervention work at this time.  As of Sunday evening, Jan. 26, crews had performed 36 hyperbaric interventions, totaling 134 hours over 10 days.

The first step after the hyperbaric interventions are completed is to advance the machine by 2 feet and build the next tunnel ring, which was in progress before the machine was stopped on Dec. 6. These 2 feet of mining and the ring build will be followed by an evaluation of the machine and its operating systems. This is necessary because the machine’s systems have been idle for seven weeks. The results of the initial mining and the extent of any required maintenance will determine when mining resumes.

Once mining resumes, the next critical milestone will be arriving at the third and final safe haven. This safe haven is approximately 500 feet ahead of the machine’s current location and was proposed by the contractor as a controlled environment for maintenance prior to mining under the Alaskan Way Viaduct and downtown Seattle. WSDOT plans to close SR 99 while tunneling occurs under the viaduct.

While we understand the interest in knowing the reasons why mining was stopped in December, it will take time to review the results of the hyperbaric interventions and consult with tunneling experts advising WSDOT. We will continue to provide the public with information as we have it and work with the contractor to ensure that the machine is ready to begin mining under downtown Seattle.

Regular updates will be provided this week when new information is available.

Previous updates
Jan. 23, 2014 update – Hyperbaric investigations continue

Jan. 21, 2014 update – Hyperbaric inspections continue

Jan. 17, 2014 update – Crews begin inspecting excavation chamber

Jan. 16, 2014 update – Working with Seattle Tunnel Partners to resume tunneling

Jan. 14, 2014 update – Diving deeper into the tunneling stoppage