Crews lower groundwater to figure out what's blocking Bertha
SEATTLE -- Crews are taking the first step toward identifying and removing the obstruction that's kept Bertha sitting idle for a week. Seattle Tunnel Partners is installing eight wells 120 feet deep at the construction site near the SR 99 tunneling machine.
An unknown object forced officials to stop Bertha about 60 feet below the surface between South Jackson and Main Streets, according to WSDOT.
The contractor says the wells will lower water pressure in the ground enough to create a safe environment for workers to assess the situation.
“We’re confident STP has the right people and the right approach in place to safely determine what’s causing the obstruction,” said Matt Preedy, Alaskan Way Viaduct Replacement Program deputy administrator. “Once they know what the obstruction is, our contractor will be able to select the best path forward.”
The contractor began installing the wells Thursday and hopes to begin inspecting the machine by late next week.
Since its start on July 30th, Bertha has dug out more than 1,000 feet. That is about one-eighth of the tunnel’s total distance.