Unique duckbill spillway for raising of Garden Route Dam

When engineering, design, and advisory company Aurecon was tasked to raise the Garden Route Dam, the main supply for water-scarce George in the Western Cape, it devised a novel solution due to unique technical constraints. The ‘duckbill’ spillway developed, so-called due to its shape, not only allowed for the dam’s existing storage capacity to be increased by 25%, it also significantly increased the discharge capacity of the spillway so as to boost the dam’s safety by preventing overtopping.

A duckbill spillway is a type of non-linear spillway, similar to the more generally-known labyrinth spillway, explains Frank Denys (PrEng, PhD), from the Water Engineering Unit at Aurecon. Aurecon is currently in the process of rebranding as Zutari, after officially announcing the separation of the African business from the Aurecon Group, effective from 1 January 2020.

The main aim is to increase the overflow length such that the spillway or weir can pass more flow for a given overflow depth. This allows for construction of very long spillways, typically four to five times longer than a linear spillway, in a limited area. The existing Garden Route Dam spillway was only 25 m wide. However, the non-linear spillway extended this distance to 80 m by curving the spillway in the upstream direction.

Read more about this project, its suppliers and scope in the next edition of Concrete Trends., out later this month.

The next edition of Concrete Trends brings news of an industry that sleeps. New projects, new ideas. New technologies, new polices. Contractors, Construction Giants, SMMEs, Suppliers. This is a world full of action, ideas and ways of managing through one of the toughest environments yet. This is the Resilience Edition