Rosie, the 530-ton tunnel boring machine, has finished tunneling on the East Side Big Pipe project, which is part of the City of Portland’s program to control combined sewer overflows (CSOs). It is the largest public infrastructure project in Portland’s history.
At its peak, more than 100 laborers — members of Laborers Local 320, and 150 operators — members of Operating Engineers Local 701, worked on the project.
Rosie started working in September 2007. It bored into the McLoughlin shaft on Oct. 18 to complete tunneling about four months ahead of schedule. Work is beginning now to prepare the nearly six-mile long, 22-foot diameter East Side Big Pipe for activation.
The tunnel will be ready to accept combined sewage by late next summer.
The $426-million sewer project is the largest construction project in Portland’s 20-year CSO control program. The Bureau of Environmental Services is working to complete several other sewer overflow projects, including the Balch Consolidation Conduit, the Sellwood Wet Weather Pump Station, the Portsmouth Force Main and Phase 2 of the Swan Island CSO Pump Station.
When construction is complete in December 2011, Portland’s combined sewers will overflow to the Willamette River an average of once every three summers and four times each winter instead of every time it rains.
Kiewit/Bilfinger Berger Joint Venture is the general contractor.