Equipment Type

You've Got Mail: Bertha Has an Eating Disorder

Overexcavation fears discussed in management emails prior to January sinkhole

April 07, 2016

Bertha, the gigantic tunneling machine currently working on Seattle's Alaskan Way Viaduct Highway 99 project, got geotechnical expert Gregg Korbin's attention when he read a daily performance report. The numbers told him the giant drill was eating dirt too fast.

“I have one burning question,” Korbin said in a January 11 email to his colleagues on the state’s five-member Strategic Technical Advisory Team. “If the [conveyor] belt weights show large overexcavation why are they allowed to continue? STP needs to gain control of the ground loss.”

Two days later, a 35-foot sinkhole opened up where Bertha was boring. Washington governor Jay Inslee immediately ordered Bertha's bosses, Seattle Tunnel Partners (STP) to stop construction.

The Seattle Times requested the emails under the Freedom of Information Act that show experts warned that STP needed stricter procedures for the project. STP disagreed.

Were the experts just being paranoid? Read more about Bertha's overexcavation incident here:

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