Whistler Creek Management & Debris Barriers
Awards & Recognition
Setting new design standards for debris containment, the Whistler Creek debris barriers can withhold a volume equivalent to 12 Olympic-size swimming pools and withstand the impact of a two-meter boulder travelling at five metres per second.
Enabling Whistler Creek Development
Intrawest’s Whistler Creekside development will be a smaller, more laid-back alternative to Whistler Village. Located on the alluvial fan of Whistler Creek, a flood and debris flow hazard zone, the development would have been impossible without the Whistler Creek Management works designed by Kerr Wood Leidal Associates (KWL).
Design Objectives and Features
The objectives of the project were to provide a high standard of flood and debris flow protection, while improving fish and wildlife habitat and creating a visually-attractive creek corridor.
The work centres around the creek above Highway 99 and consists of: two debris barriers upstream of Whistler Creekside; over 600 metres of extensively upgraded creek channel; two bridges; a secondary floodway for future emergency flood protection; and an extensive landscaping program.
Debris Barrier System
The most difficult challenge was the design and construction of the primary debris barrier. Due to its huge size and the forces it had to withstand, no standard design guidelines were applicable, making the structure a true custom-engineered solution.
The primary debris barrier is one of the largest in the province at about 12.5 metres high, with a debris storage volume of 24,000 cubic metres. It consists of rugged structural steel grillage supported by mass concrete abutments. The steel grillage is sized to withstand the impact of a boulder two metres in diameter travelling at a velocity of up to five metres per second. During a major debris flow, most debris will be contained within a bedrock ravine behind the primary debris barrier, protecting the Whistler Creekside development.
Apart from its size, it is unique in that minimal blasting and excavation was required to construct it. The minor amount of excavation required not only improved the aesthetics of the debris barriers, but also shortened the construction time and saved the client considerable construction costs.
A secondary debris barrier, of similar construction but much smaller scale, is located downstream of the primary barrier. It is designed to arrest smaller sediment surges that pass through the primary barrier thus enhanced fish habitat by reducing siltation downstream of it. Both structures are designed to withstand debris surges up to 400 cubic metres travelling at six metres per second.
The Whistler Creek works provide excellent flood and debris flow protection to Whistler Creekside and other developments downstream with the added benefits of an attractively restored creek, improved fish habitat through silt interception and creek channel enhancements, and improved wildlife habitat through planting of fruit-bearing vegetation. In fact, the debris barriers reduced the downstream risk to such an extent that no large, and potentially unsightly, engineering works were required at Whistler Creek.