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Bertha The Boring Machine
Mon July 28, 2014
Tunnel Company Says Bertha Rescue Is Already A Month Behind Schedule
Just six weeks after the contractor managing the State Route 99 tunnel project laid out its timeline for getting back to digging, the company said it’s about a month behind on repairs to its tunneling machine.
Crews are working to burrow down from the surface to where the machine known as Bertha is sitting idle. An early step is to sink a circle of interlocking concrete pillars that will line the access shaft and protect surrounding structures, but that’s proving harder than what the company was planning for in mid-June.
Seattle Tunnel Partners project manager Chris Dixon said to make the pillars nest together, crews are having to use a special chisel tool dangled from a crane to carve grooves in the adjacent pillars.
“So it’s really introducing another step into the operation. We anticipated there would be some of this but not to the extent that we’re encountering, and that’s what creating the additional time,” he said.
Dixon said the problem mostly stems from an adjustment to the original design that called for more overlap between the pillars. He said workers have sunk 53 out of 84 10-foot diameter pillars so far.
He said the company’s revised timeline, which calls for drilling to resume in March, has enough wiggle room to absorb this setback.
But State Department of Transportation project manager Todd Trepanier said he’s a bit skeptical of those reassurances. The projected completion date has already slipped back a year, while Bertha has remained immobile underground. The state and the contractor also disagree about details on who’ll be paying for the extra costs, but say that will get worked out later.
A Different Kind of Bore