East Side Combined Sewer Outflow (CSO)

Tunnel & Shaft Support

Project: East Side Combined Sewer Outflow (CSO)

Customer: Kiewit-Billfinger Berger (KBB)

Work Summary:

The East Side Big Pipe project involves 6 miles (9.7) km of tunnels and lies 150ft (46 m) below the surface along the east bank of the Willamette River in Portland Oregon.

Ballard Tunnel Support teams supported the Kiewit-Billfinger Berger (KBB) team on both tunnel and shaft support work.  On this project our team was charged with constructing the tremie slab in all launch and recovery shafts on the project. Work included mobilizing four to eight-man commercial dive teams, air and mixed gas diving equipment, multiple hyperbaric chambers, concrete breaking equipment, dredging equipment, sonar (for real time monitoring of tremie pours in low visibility conditions), specialized diver platforms for installing rods, etc. All work was completed accident free and on schedule.

Seven shafts were constructed along the tunnel alignment to provide construction and maintenance access to the East Side Big Pipe project. Each shaft is approximately 50ft ( 15.24m) diameter and 100ft (30m) deep. A slurry method was used to build the shafts

  • Project Notables:
    • Evaluation, setup and integration of hyperbaric equipment into TBM systems
    • Provided on call compressed air workers for interventions
    • Extensive shaft support
    • Provided contractor training