It’s been a lot of talk, until now, with the first sign that Bertha will move under Seattle’s waterfront.
Bertha is still at the bottom of its access pit, but crews are beginning to treat the ground in front of the tunneling machine with water and cement. The work is called “jet grouting,” and involves injecting the cement/water mixture into columns above Bertha’s path. The 5-foot diameter columns will stabilize the ground above the boring machine as it moves.
Installing the cement columns takes approximately six weeks. That puts Bertha on a rather tight timeline for when it’s expected to start boring again in late November.
Related: Bertha is prepping to move again
Bertha has been sitting at the bottom of its access pit for nearly two years after breaking down. It has been under repair ever since. In the meantime, the Washington State Department has filed a lawsuit against Seattle Tunnel Partners.