– Project: Aurecon Garden Route Dam
– Capacity: 12.5 million m3
– Type of structure: Duckbill Spillway

A duckbill spillway has been constructed on a dam along the Garden Route. The spillway has been designed to increase the surface level of the water in the dam using a weir. The result of such work has resulted in a 4.5m increase in the dam’s water level. The wall of the spillway was increased to 4.9m using earth fill on site from the dam as well as material which had been procured off site. The water level of the dam had been increased using a labyrinth type of weir which allowed the dam’s capacity to be raised by 2.5 million m3.

The sill of the spillway is a cantilever which has been fixed with rockfall on the upstream side of the wall footing, in addition to rock anchors. The channel in the spillway has a concrete coating for protection from water seepage.