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Blocked Bertha, the SR 99 TBM


Seattle Tunnel Partners (STP), WSDOT’s design-build tunnel contractor, have taken their first step toward resumption of progress of Bertha, the SR 99 tunnelling machine. STP is installing up to 10 wells approximately 36.6 m deep on the construction site near the machine, which is located about 18.3 m below the surface between South Jackson and South Main streets, to the west of the Alaskan Way Viaduct.

The wells will lower the water pressure in the ground to create a safe environment for workers to enter the excavation chamber at the front of the machine, where they'll be better able to assess the situation. High groundwater pressure combined with loose soils has to this point prevented safe worker access. Well installation started on 12.12.2013. STP hopes to begin inspecting the machine later this week. Seattle Tunnel Partners has completed only 305 m of the 2.74 km-long tunnel. For tunnelbuilder archive click here and us/69. Visit www.AlaskanWayViaduct.org and http://www.wsdot.wa.gov/News/2013/12/13_Tunnel_Crews_Look.htm. 51/13