Engineers use the words 'catastrophic failure', prompting city leaders to question safety of viaduct

SEATTLE -- Seattle's waterfront tunnel project was back in the spotlight after an alarming new letter surfaced warning of ‘catastrophic failure.’

Contractors have been digging a deep pit to reach the damaged tunnel-boring machine Bertha so they can fix it.

The ‘catastrophic failure’ is referring to that process. In a December 11 letter, engineers warned that digging too deep without further analysis of the soil could be a problem.

On Monday, the Washington State Department of Transportation said the letter was taken out of context.

“It is a misrepresentation of the Brierley report,” said WSDOT's Todd Trepanier.

The letter was written by engineers with Brierley Associates, a firm hired by Seattle Tunnel Partners. STP is WSDOT’s contractor for the Bertha tunnel-digging project.

“If we continue the current repair 'as we go' method of excavation we significantly increase the risk of a catastrophic failure. Therefore excavation shall not proceed.”

Yet, the Seattle Department of Transportation says no one ever sounded the alarm. Instead their people discovered the engineers' report through a shared database.

“This is the type of information that should have been elevated,” said SDOT's Scott Kubly.

SDOT told City Council members that the wording of the language was changed days later.

“In summary, we believe that the untreated soil zones…..will have a significant impact on the structural, geotechnical and hydraulic adequacy of the shaft structure. Our primary concern was the deletion of some language that we thought needed some explanation,” Kubly said.

The council pushed for an explanation and demanded they get a copy of the full reports.

“I have no recourse other than to be worried when I see documents like this and the fact that it’s taken a month to come to our attention,” City Councilman Mike O’Brien said.

But state transportation officials say city workers overreacted.

They say the words ‘catastrophic failure’ came out of a draft letter and it was taken out of context.

“It`s a mischaracterization of the word that is causing unneeded fear,” Trepanier said.

Trepanier continued to say, “The Alaskan Way Viaduct and the access pit that is being built to access Bertha to do repairs is safe it has always been safe.”

SDOT says they acted appropriately by bringing the issue up for clarification. And some city leaders said they were still not convinced the viaduct is safe.

“When an engineer says catastrophic failure, it must mean some importance to the public,” City Councilwoman Kshama Sawant said.

The excavation or digging of the access pit has stopped until further analysis.

WSDOT says they are thinking about limiting SDOT’s access to the shared database but some council members said that wasn’t a good idea.