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Drill's over: A two-year effort to bore beneath the Willamette concluded Monday

Article from Daily Journal of Commerce, August 2, 2005

After about two years of mining work, the last of two original tunnel boring machines that dug a 14-foot diameter, three-and-a-half mile tunnel for Portland's nearly $300 million West Side Big Pipe project has reached the end of the line.

Workers dismantled the machine inside a 12-story-deep shaft at the corner of Clay Street and Naito Parkway in downtown Portland over the weekend, and crews hoisted out sections of the machine on Monday.

The fist section of the machine to be removed was its 16-foot-diameter cutterhead.

Watching the cutterhead rise from the depths of Portland's newest sewer tunnel, Linc Mann, a Bureau of Environmental Services spokesman, called its removal a "spectacular" event.

"That thing has done a lot of work," Mann said. "It's chewed through a lot of sand and gravel and rocks, which is a pretty incredible feat."

With the mining portion of the project now finished, Mann said, the tunnel is now essentially complete. But crews from the joint venture Impregilo/Healy, the general contractor for the project, still have about a year's worth of work and tests to complete before the tunnel will be ready for operation.

Giuseppe Quarta, the project director for the West Side Combined Sewer Overflow project with Impregilo/Healy, said that the project, which is ahead of schedule and on budget, has been a success.

"It has been a complete success," Quarta said. "Obviously, we're very pleased."

The West Side CSO project is designed to reduce the volume of untreated combined sewage overflows into the Willamette River that occur when heavy rainstorms inundate the sewage system, which mixes untreated sewage and stormwater.

Work includes construction of the pipeline on the west side of the Willamette River and a large pump station on the east side of the river on Swan Island.

The Swan Island pump station will eventually be the connecting point between the east and west side sections of the 20-year CSO project.

The east side section of the project, which will be constructed by the joint venture Kiewit/Bilfinger/Berger, is still in the planning stages and has not yet been constructed.

KBB won the right to construct the approximately $500 million east side section of the project after receiving more points than the joint venture of Impregilo/Healy/ Obayashi in a selection process and surviving a lengthy appeals process.

Impregilo/Healy's work on the project will end when the work on the west side section of the project is completed.

Before the city started implementing the project in 1991, combined sewer overflow amounted to six billion gallons. The city estimates that amount will be reduced by 94 percent when the project is completed in 2011.