Feb. 26 project update: Mining continues

Posted on Feb 26 2016 3:27 PM
Bertha, the SR 99 tunneling machine, has mined 25 feet and built three concrete tunnel rings since mining resumed on Tuesday. At the time of this post, crews were installing the fourth ring.
Crews took a break from mining on Thursday to stabilize the ground behind the machine. Grout was injected above a section of the tunnel that was mined before WSDOT ordered the Jan. 14 suspension for cause. Mining was ongoing on Friday and was scheduled to continue through Saturday, according to STP. Crews will take Sunday off and mine again next week. 
As part of the conditions for lifting the suspension for cause, STP has been permitted to tunnel forward and install approximately 25 concrete tunnel rings. During this time, they must demonstrate that they have implemented a number of changes to ensure they can safely continue mining. Details of the changes are included in this post.
We’ll continue to provide updates as STP’s work progresses.
Recent updates 
For earlier program updates, please visit our archive page.


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