Jan. 16 update: Working with Seattle Tunnel Partners to resume tunneling

Posted on Jan 16 2014 3:56 PM

One reason Seattle Tunnel Partners (STP) was selected to build the SR 99 tunnel was because of their tunneling expertise. In particular, we were drawn to one component of their proposal, which involved building a protected underground area along the first 1,500 feet of the tunnel drive.

In addition to protecting the viaduct and other structures in this very shallow, challenging section of the route, this protected area allows the contractor to test all functions of the tunneling machine and its operations prior to tunneling under downtown Seattle.

Letter to STP
We’ve had concerns about the SR 99 tunneling machine’s operations and critical systems since its launch on July 30, 2013. We have discussed these concerns with STP frequently over the past five months.

This week, we sent a formal letter stating our concerns and asking STP how they plan to address them. A copy of the letter won’t be made public because it could be the subject of a potential future litigation between WSDOT and the contractor.

Our request for information is not an attempt to tell STP how to do their work. If we did that, we could bear responsibility for the cost and risks associated with those actions. We asked for the following by close of business Wednesday, Jan. 15:

  • Status of features needed to operate the tunneling machine as described in their proposal
  • Potential causes of wear to cutting tools, screw conveyor and other parts
  • Information about possible deviations from planned operating procedures
  • Details about changes to soil conditioners prior to stoppage
  • Soil conditioning plans moving forward
  • STP's Mining and Intervention Plan schedule
  • List of factors and decisions that led to operating machine at extremely high temperatures prior to stoppage on Dec. 6
  • Information about experts STP has engaged since stoppage
  • List of potential schedule-recovery opportunities

Bringing in outside experts
We are assembling a panel of tunneling experts to review, evaluate and provide opinions on the following:

  • Any concerns, limitations or recommendations regarding the tunneling machine and its ability to perform the work ahead
  • Management and operations of the tunneling machine
  • Adequacy of and/or further improvements to the planned steps to resume tunneling
  • Whether efforts to get the machine moving again are progressing satisfactorily
  • Whether the right decisions have been made by various stakeholders engaged in the tunneling work to date


The panel will also provide a template approach to be adopted for addressing similar, critical events that may occur in the future. We have requested that STP accommodate these experts as they evaluate intervention and repair operations and assess the machine’s ability to resume tunneling.

We’ll continue to provide you with updates as we move forward.

Previous updates

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

Jan. 13, 2014 update -- Filling in shaft number three

Jan. 10, 2014 update -- Exploratory shaft work continues

Jan. 9, 2014 update -- Still too early to talk timeline 

Jan. 8, 2014 update -- Crews continue drilling exploratory shafts