State halts Bertha tunneling after sinkhole forms near waterfront

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SEATTLE (AP) — The state has halted the digging of the new Highway 99 tunnel under downtown Seattle after a sinkhole formed along the waterfront.

Gov. Jay Inslee and the Department of Transportation said Thursday they ordered Seattle Tunnel Partners to suspend digging operations by the massive tunnel-boring machine known as “Bertha” until the contractor can determine what caused the sinkhole and ensure that similar problems don’t occur again.

Bertha recently resumed work after a roughly two-year shutdown and expensive repairs. The contractor has poured concrete and sand into the sinkhole, which developed Tuesday night.

State transportation officials say they have not detected any movement of the elevated Alaskan Way Viaduct related to the sinkhole.

Below is the full statement from Secretary of Transportation Lynn Peterson:

“In light of recent incidents on the SR 99 Tunnel Project, WSDOT is notifying the contractor that they must suspend tunneling work for cause. I share the Governor’s concern for public safety and we want to ensure that the contractor has the right protocols in place to proceed with their work safely.

We are asking that the contractor complete root cause analysis and take the appropriate steps to ensure that incidents, such as the sinkhole near the repair pit, do not occur again. STP will not be allowed to resume tunneling until their analysis and work plans meet the satisfaction of our experts.

I want to remind everyone that replacing the viaduct is critical to public safety. We have conducted surveys of the viaduct and no movement has been observed; surveys will continue. The tunneling work must proceed, but it must proceed safely.”

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