Wivenhoe Dam Upgrade
South-East Queensland, Australia
Wivenhoe Dam is situated approximately 50 km west of Brisbane in Queensland. Construction for the original dam was completed by 1985 to provide flood immunity for the Brisbane River after the devastation caused by the floods of 1974. Since the original dam design, meteorological predictions for maximum rainfall events have been increased as a result of global climate change so that there was a risk that the dam wall was unsafe.
To minimise the risk of dam failure for a 1 in 100,000 year flood event, a new spillway chute was built on the right hand side of the existing dam embankment. An incremental release of rising flood waters is allowed for by three separated earthen fuse plugs with varying trigger levels within the spillway. This option was chosen after extensive hydraulic and flood modelling was undertaken to achieve the most satisfactory outcome in the event of a flood exceeding the dam capacity.
Key features of the project were:
- Three earth embankment fuse plugs separated by 14 m high cantilever retaining walls within a new spillway chute
- A new 170 m long road bridge over the spillway chute to maintain the existing Brisbane Valley Highway
- Post-tensioned strengthening of the existing concrete spillway wall
- An upstream wave wall to increase the overtopping height of the dam
- Improved access to the Sout East Queensland Water Visitor and Information Centre
- Significant landscaping and environmental rehabilitation works
Maunsell as sub consultant to the Alliance partners was involved with many of the project features, and took a lead role in the design of the structures, bridge, and civil and road works. Many of the value adding incentives throughout the design and construction phases were a direct result of Maunsell’s ability to meet client’s requirements using the latest technology and processes.
The project has had many outstanding successes for the numerous challenges that the Alliance faced.
