Concrete Drop Structure
Description
These structures are similar in design to gully head structures. Usually built as a free standing wall. Drop usually limited to 3 metres. Cost $20,000 plus.
Application
Used to control active bed erosion. Often installed to protect an upstream asset such as a bridge or culvert.
Limitations
Drop height is usually limited by channel capacity.
Requires rock bar or stable channel downstream to prevent undermining.
Forms a barrier to fish and other aquatic fauna.
Comments
Expensive to build because of difficult site conditions. Requires deep foundations into floor and banks to prevent failure.