Wyaralong Dam design and construction
Client: Queensland Water Infrastructure
Location: Queensland, Australia
Date: February 2009 – February 2011
Designing a roller-compacted concrete dam to improve water storage and provide long-term reliable water supply.
Background
In response to the water shortage in south-east Queensland, the Queensland government initiated a project to develop the Wyaralong Dam to improve the storage and use of water in the Logan River catchment.
The objectives of the construction of Wyaralong Dam are to contribute to the development of long-term reliable water supplies for south-east Queensland by constructing a dam in the Teviot Brook capable of providing up to 21 000 ML per annum to the water grid, when operated with Cedar Grove Weir.
Solution
Entura designed a 50m high, 490m long roller-compacted concrete (RCC) dam with a centrally located ungated primary spillway and stilling basin. The dam has a secondary spillway on the left abutment with an apron directing the flow back into the stilling basin. The total volume is approximately 185 000 m3.
The outlet works and fishway are located on the right abutment. The dam has a wet intake tower on the upstream face of the dam which can draw water from various levels. The water is discharged back to the river through two submerged vertical discharge valves.
Entura’s developed a number of innovative solutions to the project’s challenges:
- despite initial durability concerns, an extensive investigation and trial program was conducted to prove the suitability of using the onsite clay cemented sandstone aggregate for the RCC mix
- an innovative bi-directional fish lift was developed, combining known technology to develop a unique and innovative design to meet the approval requirements for fish passage in both directions over an extensive operational range
- foundation stability was explored through testing and analysis of weak bedding plane features.
Outcome
Throughout the project the design team worked closely with the construction contractor and client to develop a design that was both cost-effective and of an appropriate quality for its purpose.
This was done through structured value engineering processes, by realising opportunities as they arose, by effectively managing the risk and pursuing innovative solutions using proven technology.
