Going down to see what’s up – WAY down, in the Big Pipe Project

By David F. Ashton

The Bee, Jan 30, 2008, Updated Oct 30, 2009

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These ring segments are made on-site, using some of the spoils from the tunneling operation. They – and all other equipment and supplies – are lowered down the Opera Shaft by a huge construction crane, which for those just driving by is the most visible evidence of the construction project in Southeast Portland.

Yanagisawa continued, “This operation is a continuous process. Everything has to be working at all times – the TBM, the slurry plant, separator, the grout plant, ventilation system, and the ring manufacturing.”

Portland City Commissioner Sam Adams, joking that he’s “The Sewer Commissioner”, exited the elevator, coming up from his tour of the project, just as we members of the press were preparing to descend.

“This is the first time I’ve had the opportunity to tour the East Side project,” he explained. “This is an effort to reduce, by 94%, the sewer overflows into the Willamette River. We’ll have spent $1.4 billion, when all of the tunnels have been dug and pumping stations have been installed. We’re now about 66% complete on the overall project.”

Our group then climbed into a construction elevator affixed to the side of the shaft for our ride to the bottom. Along the walls of the 67-foot-wide shaft are the electrical conduits that power the TMB, the incoming and outgoing slurry pipes, and the large ventilation duct.

On the bottom of the huge shaft are train tracks, on which runs a “Loki” – a squat but powerful diesel engine and passenger cars.

Once aboard, we rumbled northbound, heading through the tunnel toward the current end of the line: The TBM rig. The tunnel was temperate and dry, and we saw segments of the concrete liner rings along the way.

Because this was a system-maintenance day, the TBM was silent when we exited the train, about a mile north of the Opera Shaft.

Greg Colzani, Tunnel Manager, told the group that the TBM is about 30 feet long – but the equipment behind it, including the devices used to set the ring segments in place, is about 70 feet long. As the drilling rig inches forward, the100-foot long assembly is pulled along with it.

“The TBM has now entered the Alder Street Shaft, where the old ‘Corno’ building once stood,” Colzani told us. “Standing here behind the machine, we’re right below the Montage Restaurant.”

Brooklyn tunneling begins in 2010

From the Alder Street Shaft, the crew will keep mining northward to the Swan Island pumping station. “When we reach that point,” Colzani said, “We’ll take the machine apart. Then we’ll haul it back to the Opera Shaft, and reassemble it there for its trip south. It will tunnel from there about 8,000 feet to our [southernmost] shaft on the north side of S.E. McLaughlin Boulevard at S.E. 17th Avenue.”

And, when it arrives there in 2011, Colzani said, another giant crane will be built there to lift out the TBM, including its 160-ton main bearing.

A large, but smaller, tunnel will then be bored south a short distance to the intersection of S.E. 18th and Insley, where the “Insley Collector” pipe which collects sewage from throughout Inner Southeast Portland will be connected to the “Big Pipe” via this new, final tunnel.

That will complete a project that Commissioner Adams said he considers to be a “100-year project that will prevent all but the worst overflows into the Willamette River. And keep the sewer system functioning for the next century.”

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