2025 West Best Projects
Award of Merit, Small Project: Round Butte Dam Spillway Tunnel Aerator
Round Butte Dam Spillway Tunnel Aerator
Madras, Ore.
Award of Merit
Submitted by Syblon Reid
Owner/Engineer/Construction Management Portland General Electric
Lead Design Firm Schnabel Engineering
General Contractor Syblon Reid
Subcontractors Condon-Johnson & Associates Inc.; Northwest Scaffold Service Inc.; M2 Integration LLC; Smith Monroe Gray Engineers Inc. (SMG); Eastern Oregon Iron Co.; Fabrication Products Inc.; CEI Forms Inc.
This critical dam infrastructure upgrade, located 200 ft down a spillway tunnel at a sustained 52-degree slope within Round Butte Dam, is only the fifth retrofit concrete tunnel aerator constructed in the U.S.
The project was mandated during a turbine intake valve replacement design analysis to mitigate possible cavitation damage during spill events, making this the first retrofit installed proactively to prevent damage rather than in response to failure.
The contractor-designed access system was central to the project’s success. Engineered scaffolding and a custom rolling platform powered by twin hydraulic winches span the tunnel’s full perimeter and slope, enabling safe access throughout construction.
Following FERC-approved drilling and chemical grouting to stabilize substrate and control seepage, the team initiated tunnel demolition using a Brokk 170 remote-controlled hydraulic breaker. Despite encountering unexpected sandstone geology that extended drilling operations and required field adaptations, the team maintained tunnel stability and safety.
