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How far has Bertha moved since restarting mining operations this week?

Bertha has been at work ever since the state gave conditional permission to start digging again. The tunnel above was constructed before the machine was repaired over the past two years. (WSDOT)

Bertha has been at work ever since the state gave conditional permission to start digging again on Tuesday. How far has the boring machine gone since then?

Bertha has moved forward 25 feet. Tunneling crews have installed three concrete rings in its wake. A fourth ring is expected to be completed by the end of the work week on Saturday.

Replace: Why WSDOT allowed Bertha to move forward after it created a sinkhole

The Washington State Department of Transportation has allowed the contractor, Seattle Tunnel Partners, to move forward and place a total of 25 rings. That will factor out to be around 160 feet. If WSDOT approves of the operation to that point and believes it is safe to move ahead, Bertha will be allowed to move forward another 100 feet to a planned maintenance stop.

Bertha stopped boring operations on Thursday so that crews could stabilize the ground behind its path. Tunneling crews injected grout into the ground above the tunnel that Bertha previously constructed. That tunnel was bored before the state ordered the contractor to halt all operations on Jan. 14.

The contractor, Seattle Tunnel Partners, plans to continue mining through Saturday, take a day off on Sunday, and start back up again sometime next week.

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