CWA was retained by Metro Vancouver to design a new hydraulically-actuated spillway gate in one of the twelve spillway bays on the Seymour Falls Dam, which impounds a reservoir that supplies approximately one third of the drinking water for the Metro Vancouver region.
The new gate allows environmental flexibility for the yearly fish migration from the reservoir and improves safety by reducing the need for workers to access the reservoir and spillway areas.
The location of the spillway gate created challenges in coordinating construction with active reservoir operation. As a result, personnel access was limited and closely monitored. Protection of the sensitive environment and regional water supply was also of paramount importance.
The gate’s design needed to fit into the existing geometry of the spillway, which was completed in the early 1960s. The custom design required detailing for the seals and attachment of the system to the heavily-reinforced concrete structure.
CWA generated a new concept that included:
- The use of environmentally-friendly hydraulic fluid.
- Access to hoist equipment from the bridge deck level.
- Easy attachment to the spillway.
- Seismic isolation from the bridge deck.
- Vertical installation and operation.
CWA worked with the construction contractor’s surveyors and used 3D laser scanning and 3D modelling to adjust the design drawings and ensure an accurate, leak-free fit between the new gate and the existing spillway. The required shutdown time was minimized and the capital cost was reduced through coordination with Metro Vancouver and the contractor.