Hitachi built a new seal ring in Japan for its stranded tunnel-boring machine, and it arrived Friday at Seattle’s Terminal 46.
The state Department of Transportation tweeted photos of new seal ring, as well as the new bearing.
Previously, Seattle Tunnel Partners (STP) said it kept a spare bearing, a requirement of its $1.44 billion contract to build the four-lane Highway 99 tunnel from Sodo to South Lake Union. In early December, the rotary cutting drive overheated, and grit penetrated the rubber seals that protect the German-made bearing. The new Hitachi seal ring contains stiffer material, and the front end generally will be strengthened by steel rods and plates.
A deep repair vault is being excavated in front of tunnel machine Bertha so STP can remove and replace the main components, with hopes to resume drilling in March. But this week, archaeologists have taken over the repair pit to investigate a deposit of shells. As of Thursday, the team found small Olympia oyster shells and butter clams, but no sign of human remains, nor Native American artifacts — so its work might be finished soon.