Alaskan Way Viaduct Settles after Bertha TBM Access Pit Dewatering

Contours of Settlement around the Bertha access pit de-watering as of December 10, 2014

Areas surrounding the access pit being excavated to rescue the stalled Bertha TBM have experienced settlement as much as 1 to almost 1.5 inches according to a draft figure released by WSDOT on December 11, 2014. The aging and seismically deficient Viaduct itself has experienced 1 inch of settlement as well. Structural engineers have inspected it as well as numerous buildings in the area and have not found structural damage. The settlement is thought to be related to the dewatering associated with the access pit construction. The excavation was within 3 feet of the bottom when the settlement issues were first announced on December 5, and WSDOT has since allowed the contractor to complete the excavation. [Source: Read more information in the update provided by the WSDOT Alaskan Way Viaduct Replacement Project team. Image: WSDOT]