Bertha, The Giant Borer That Broke, May Be Sinking Seattle's Downtown

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And a year ago this week, Bertha came to a grinding halt. That would be Bertha, the nickname for the world's largest tunneling machine that was boring a new highway tunnel under Seattle's downtown. As NPR's Martin Kaste reports, Bertha's breakdown last December has led to a gigantic, new problem for the city.

MARTIN KASTE, BYLINE: Seattle's Pioneer Square is sinking. At least, that's what the residents are seeing in this 1895 vintage building. Bob Christophel demonstrates how the fire doors suddenly seem to be catching on the floor.

BOB CHRISTOPHEL: No, it won't close all the way on its own.

UNIDENTIFIED MAN #1: Yeah.

KASTE: What is your theory about what's happening here to this wall and to this...

CHRISTOPHEL: Well, we think there is a settlement or, you know, a change to the structure itself.

KASTE: The source of this settling may be Bertha, the tunneling machine which developed mechanical trouble deep underground almost right in front of the building. Or to be more exact, the problem may be the giant, 12-story deep pit that they're now digging to reach Bertha and fix it. Todd Trepanier is the man overseeing the project for the state. He says the problem may be all the water that's being pumped out of the ground as they dig the pit.

TODD TREPANIER: It appears that underground waters have been affected, which may have influenced ground settlement in the Pioneer Square area and affected it in a broad scope that was larger than what the Seattle Tunnel Partners's engineers felt like could happen.

KASTE: Did you catch that mention of Seattle Tunnel Partners? That's the contractor, and lately, state employees have been making a point of saying that Bertha is the contractor's problem and insisting the cost overruns will not be the state's responsibility. That may end up being a matter for the courts. In the meantime, this rescue project is monumental. Trepanier, an engineer by training, can't help but be impressed by the scale of the fix.

TREPANIER: They're going to try and lift 2,000 tons of machine out of the ground, spin it, set it down on the ground, disassemble it, replace the bearing because the bearing oils are contaminated and then put in a newly designed seal system.

KASTE: All that in a tunneling machine that's already underground and a thousand feet into its project. But at the moment that fix will have to wait as state inspectors knock on doors to try to find out whether all of this is doing damage to some of Seattle's most historic buildings. Martin Kaste, NPR News, Seattle. Transcript provided by NPR, Copyright NPR.