WILLIAMETTE RIVER CSO TUNNEL PROGRAM
City of Portland

The East Side CSO Tunnel Project

This is the largest of all Portland's projects to greatly reduce the overflows to the Willamette River. When this project is complete in 2011, the volume of combined sewage and stormwater that now overflows to the river when it rains will be reduced by more than 94%. The sewer tunnel is 22 feet in diameter and will be six miles long. EPC is providing a Project Controls Manager, Schedulers and an Inspector as part of the Construction Management for the Eastside CSO.

 

West Side CSO Tunnel Project

As part of Portland's program to reduce combined sewer overflows (CSOs) along the west side of the Willamette River, the West Side CSO Tunnel was constructed to capture sewage and stormwater on the west side of the Willamette River. The 14-foot diameter, 3-1/2 mile long tunnel extends from SW Clay Street to Swan Island. The tunnel's purpose is to collect storm water and waste water from the west side of the river and transport it to the Columbia Boulevard Wastewater Treatment Plant in north Portland. Site restoration has occurred at all five West Side Big Pipe tunnel shafts. The shafts connect the existing sewer system to the new tunnel and are being used for long term operations and maintenance access. EPC Consultants provided construction management services for this technically challenging project. Services included project controls management, and tunnel inspection. EPIC's participation included preparation of the owner's budget cost estimate, project controls, and assistance negotiation with the contractor. Additional Key Highlights of the CSO Tunnel Program include:

  1. This project involved the first and most successful large diameter slurry tunnel boring machine in North America (for a total of 10 miles -- one of the longest STBM driven tunnel systems in the world)
  2. This project involved the longest microtunnel drive in the United States (3000 lf); with 12 major large diameter deep shafts next to the Willamette River in saturated conditions under 100 feet of ground water head.
  3. The team built one of the largest underground pump stations in the United States, rated at 220 mgd in a large shaft, and under high groundwater head
  4. The $1.4 billion program was completed within the budget and on time without claims.

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