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

Posted on Mar 13 2014 7:08 PM
Seattle Tunnel Partners has submitted its preliminary plan for accessing the SR 99 tunneling machine to make repairs. Currently under review by WSDOT, the design for a circular access pit could be finalized as early as next week. The 120-foot-deep pit would be constructed in the closed portion of Alaskan Way South between South Jackson and South Main streets.
As part of the project’s environmental review process, WSDOT must consider potential impacts to cultural resources. Because excavation from the surface to approximately 120 feet deep was not anticipated or included in the initial environmental review, WSDOT is completing additional cultural resources survey work. This work is being coordinated with the Washington State Department of Archaeology and Historic Preservation (DAHP) and tribal governments that are consulting on the project.
To analyze the ground in the area, crews will dig approximately 60 exploratory holes near the tunneling machine’s current location. The holes will be 4 inches in diameter and between 20 and 40 feet deep. Project archaeologists will be on hand to investigate soil composition and any material that may have archaeological importance. This part of the waterfront was built up using historic fill material. The top of the tunneling machine is currently located 60 feet below the surface in soil that predates human settlement.  
As part of WSDOT’s cultural resources compliance, a plan is already in place for inadvertent archaeological discoveries. This plan was developed during the environmental process and is closely coordinated with DAHP and tribal governments.

Previous updates 

Feb. 28, 2014 update - A week in review: Bertha repair plan, ERP’s 2014 report and a viaduct weekend closure reminder

Feb. 27, 2014 update - How is an early or late tunnel opening addressed in the design-build contract?

Feb. 25, 2014 update - Ground settlement near the viaduct is safe, expected

Feb. 21, 2014 update – Seattle Tunnel Partners will dig access shaft to reach tunneling machine

Feb. 14, 2014 update – Repair plan to be finalized by the end of February

Click here to see a full archive of progress updates