Oregon CSO tunnel nominated for OCEA

The American Society of Civil Engineers (ASCE) announced Portland’s Willamette River CSO Tunnel Program as one of the five finalists for the 2012 Outstanding Civil Engineering Achievement (OCEA) award.

Part of Portland’s 20-year program to control combined sewer overflows (CSOs), the Willamette River CSO project consisted of constructing tunnels on both sides of the Willamette River, several tunnel shafts and connecting pipelines, two pressure sewers and a large pump station.

The ASCE recognises a project that “best illustrates superior civil engineering skills and significantly contributes to civil engineering progress and society” with the annual award. The winner will be announced at an award ceremony in Washington, D.C. next March.

Two slurry pressure TBMs were used to construct the 3.5-mile (5.6km) long, 14ft (4.3m) diameter West Side CSO tunnel, at depths ranging from 100ft to 150ft (30.5m to 45.7m). This was completed in variable ground conditions below the water table. Another slurry pressure TBM mined the 6-mile (9.7km) long, 22-foot (6.7m) diameter East Side CSO Tunnel.

Key players in the project include: A contractor joint venture of Impregilo/S.A. Healy for the West Side CSO tunnel; a contractor joint venture of Kiewit–Bilfinger Berger for the East Side CSO; Parsons Brinckerhoff for design and Jacobs Associates for construction management.

As of summer 2011, the City was in the process of activating the tunnel.

The City of Portland said it developed an “innovative” contracting method specifically for the tunnel projects, which was “instrumental in the city completing both the USD 293M West Side Tunnel project and the USD 426M East Side Tunnel ahead of schedule and under budget.”