More delays for Bertha, viaduct project

Another tough break for Bertha. Further delays are expected for the giant tunnel machine and Seattle’s viaduct project.

The Washington State Department of Transportation told the Seattle City Council Monday that damage to Bertha will delay its progress further.

“Even though the damage is more than they were expecting to find, it’s not more than they were planning to repair at this point,” said Todd Trepanier with WSDOT.

For example, WSDOT said the outer seals and the steel retainers that hold them in place were destroyed. There was also damage to the cutter drive motor pinions and the main bearing bull gear.

Minor damage also occurred during disassembly.

Crews have also decided to replace the inner seals to make them more compatible with the new outer seals and main bearing. Those new seals have to be manufactured in Japan and won’t arrive until late May.

It is up to the Seattle Tunnel partners as to how long the project will be delayed.

So who’s going to pay for all this? WSDOT said STP and Hitachi are responsible for all aspects of the repair effort. WSDOT tells KIRO Radio’s Josh Kerns a dispute resolution is far down the road and it’s not a priority right now.

In addition to the damage, WSDOT told the City Council there are no simple answers as to why the ground near the SR 99 tunnel access pit settled about an inch last November.

One report, done by geotechnical firm Shannon & Wilson, Inc. and commissioned by WSDOT, said that dewatering related to tunneling machine repairs was the primary cause of the settlement.

A second report, concluded by Brierley Associates and commissioned by Seattle Tunnel Partners, said natural settlement and other dewatering activities are the primary reasons for the settlement, and tunnel-related dewatering only contributed in areas immediately surrounding the pit.

While the reports may differ slightly, they both conclude that settling related to dewatering has since stabilized, and ground movement was minor and caused no structural damage.

Richard D. Oxley contributed to this report