Construction of access pit’s underground walls now underway

Posted on May 13 2014 4:17 PM

Seattle Tunnel Partners has started building the underground walls of the circular pit (pdf 2.5 Mb) crews will use to access and repair the SR 99 tunneling machine. On Tuesday, May 13, large blue drill rigs began work to install the first of 73 piles that will enclose the 120-foot-deep pit.

Crews have been relocating utilities and injecting grout into the ground above the machine since the access pit received environmental clearance last week. Construction of the underground walls is beginning slightly earlier than STP’s most recent schedule indicated. Pit excavation is slated to begin in late July and last through September. STP plans to resume tunneling by the end of March 2015.

Measuring progress

  • You can watch the access pit take shape at our newly installed time-lapse camera.
  • These graphics (pdf 2.5 Mb)  illustrate the steps STP is taking to resume tunneling by the end of March 2015.


Previous updates 

May 8, 2014 update - With environmental review complete, access pit construction begins in earnest

April 29, 2014 update - A summary of change orders on the SR 99 Tunnel Project

April 21, 2014 update - SR 99 tunneling machine to resume digging in March 2015

April 3, 2014 update - Setting the stage for Bertha's repairs

March 13, 2014 update - Seattle Tunnel Partners submits repair plan, archaeological surveys underway

Click here to see a full archive of progress updates