Crews say they have to build another pit similar to the machine's launch pit to repair the broken boring machine. The plan now is to begin repairs on Bertha this fall, begin testing in February and get her digging again by March.
The timeline means a 16-month delay in boring, but the state Transportation Department says that the contractor, Seattle Tunnel Partners, hopes to shave off four months to meet the DOT's original target for opening the new State Route 99 tunnel in November 2016. Seattle Tunnel Partners had a late 2015 opening date in their original proposal.
"Resuming tunneling will take longer than any of us would have liked, but making these repairs is a significant engineering challenge that must be done safely," Chris Dixon, Seattle Tunnel Partners project manager, said in a press release. "We are committed to this project, and to taking the necessary steps to recover time and open the tunnel to drivers by WSDOT's original target date."
STP said repairs will include replacing the machine's main bearing and installing a more robust seal system that would have redundant systems and monitoring equipment. Additional repair details will be released on June 16.
DOT officials say work continues on as planned on other sections of the tunnel project, including $750 million worth of work at the tunnel portals and along the highway 99 corridor.
Bertha ground to a halt in December due to damaged seals that protect the drill's main bearing. The machine has only made it 1,000 feet into the 1.7-mile Highway 99 tunnel that will replace the Alaskan Way Viaduct.