WES tunnel boring machine retrieved from Oregon river after seven-month project

The Clack-A-Mole Tunnel Boring Machine (TBM) was retrieved from the Willamette River in Oregon City, Ore., at the end of January after being submerged for more than seven months. The Clackamas Water Environment Services (WES) shared that during that time, the 250,000-pound machine drilled a half-milelong, nine-foot-diameter tunnel to construct a new outfall pipeline to transport treated water from the Tri-City Water Resource Recovery Facility in Oregon City.
The treated water, called “effluent,” is then sent to the Willamette River. An outfall is the discharge point where the treated water flows into the river. This is one of the last steps in a significant infrastructure project necessary to accommodate growth.
"Without this type of infrastructure, we're not able to provide the necessary services to homeowners, and we're not able to build so that people have a place to live," shared Martha Schrader, Clackamas County Commissioner.
“The outfall project and subsequent retrieval of the tunnel boring machine from deep in the Willamette River is one of the biggest and most impressive engineering accomplishments I’ve had the pleasure to witness,” added WES Director Greg Geist.
Every day, WES cleans more than 10 million gallons of wastewater at its Tri-City Water Resource Recovery Facility in Oregon City.
Built in 1984, the current outfall is nearing capacity during peak wet weather events. The replacement outfall will be large enough to provide service for decades. Operation of the outfall is expected to begin in 2025.
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