WSDOT lifts suspension, allows Bertha to continue digging SR 99 tunnel
SEATTLE -- State officials have lifted the suspension that halted Bertha from continuing to drill the SR 99 tunnel in downtown Seattle.
WSDOT says the contractor, Seattle Tunnel Partners, has been given conditional permission to continue mining. The contractor is being allowed to tunnel forward and install approximately 25 concrete tunnel rings.
In January, the state halted the digging of the new tunnel after a sinkhole formed along the waterfront.
State officials say STP must demonstrate that they have implemented a number of safety changes to ensure they can continue safely mining.
“WSDOT, in consultation with its team of tunnel experts, lifted the suspension of tunneling for cause and said that conditional tunneling should resume for 25 more tunnel rings. I concur with their decision, and WSDOT has notified the contractor,” said Gov. Jay Inslee. “The contractor has a plan for modifying tunnel operations to ensure positive ground control. It has also made changes to key personnel, and it has put in place protocols for quality control and assurance. The contractor now has an opportunity to show progress during this test period, prior to tunneling under the viaduct and underneath Seattle.”
The changes include:
WSDOT made the decision to conditionally lift the suspension for cause after its team of experts went over documentation submitted by the contractor.
"While mining can resume, barging activities are still restricted pending submittal of additional documentation. STP will remove excavated soil by truck as they continue addressing the barging issue. Repairs to the pier that was damaged during the Jan. 12 barging incident were completed earlier this month," officials wrote in a news release.
Bertha recently resumed work after a roughly two-year shutdown and expensive repairs.
The project, which is meant to replace the Alaskan Way Viaduct, is two years past its projected completion date and more than $200 million over budget. The state has said it doesn’t have a backup plan if the tunnel project fails.
State transportation officials say they have not detected any movement of the elevated Alaskan Way Viaduct related to the sinkhole.
What's next?
"The tunneling machine is currently located west of the Alaskan Way Viaduct, near South Washington Street. The conditional lift will remain in place for approximately 160 feet of tunneling. During this period – which is considered part of STP’s initial testing phase – STP will be operating with additional communication with WSDOT and its tunneling experts. If STP demonstrates that their revised mining procedures are effective, crews will continue mining an additional 100 feet north to a planned maintenance stop. Once there, crews could spend several weeks performing final maintenance before the machine tunnels beneath the Alaskan Way Viaduct," officials wrote in a news release. "WSDOT will fully close SR 99 through downtown for approximately two weeks while the machine passes beneath the viaduct. The closure date will depend on the tunneling machine’s progress. Check www.99closure.org as the closure approaches for additional details."