Aug. 24 project update: Seattle Tunnel Partners planning to lower Bertha into the access pit today

Posted on Aug 24 2015 7:11 AM

5:30 p.m. update: The front end of the tunneling machine has been partially lowered into the access pit. Crane crews will break for the evening and lower the piece to the bottom of the pit on Tuesday. Look for an update in the morning.

12:34 p.m. update: With the front end of the tunneling machine now suspended above the access pit, crews have begun rotating it vertically. When the piece is in position, crews will begin lowering it toward the bottom of the pit. F ollow @BerthaDigsSR99 on Twitter for updates. With the front end of the tunneling machine now suspended above the access pit, crews have begun rotating it vertically. When the piece is in position, crews will begin lowering it toward the bottom of the pit. F

A shot of the machine's front end suspended over the access pit.

11:14 a.m. update: The front end of the tunneling machine has been safely lifted off the ground. Crews have begun moving the crane horizontally toward the access pit. You can follow @BerthaDigsSR99 on Twitter for updates. The front end of the tunneling machine has been safely lifted off the ground. Crews have begun moving the crane horizontally toward the access pit.

***

After completing motor installation over the weekend, Seattle Tunnel Partners is nearly ready to lower the SR 99 tunneling machine’s newly reassembled front end into the access pit.

Crane crews have finished connecting the 2,000-ton piece to the crane and are performing final tests. They expect to begin the lift later this morning. Lifting and lowering the piece into the 120-foot-deep pit could take 14 hours or more, but there is no set schedule. Crews will take as long as necessary to prepare for and safely complete their work.

The front-end section is the largest of four pieces that will be lowered into the pit for reassembly in coming days. The section being lifted today includes the machine’s cutterhead, motors and the new main bearing assembly.

The crane doing the lifting was built by Mammoet, a firm that has performed similar lifts around the world, including the successful recovery of a Russian nuclear submarine from the bottom of the Barents Sea. Equipped with nearly seven miles of steel cable, the crane lowering Bertha into the pit is capable of lifting more than 2,400 tons. This video (links to YouTube) shows what it looked like when Mammoet lifted this section of the machine from the pit on March 30. This narrated video (links to YouTube) explains the entire repair sequence in detail.

Once the front end of the machine is in place at the bottom of the pit, crews will begin reconnecting wires, hoses and cables to the portion of the machine that remains in the ground. STP’s latest schedule shows that three pieces of the machine’s outer shield will be lowered into the pit for reassembly in the days following the front-end lift. A series of tests will follow reassembly to ensure the machine is ready to resume mining.