Lake Macdonald spillway work to start in 2019
UPGRADING a major dam is not a simple task.
And that includes Lake Macdonald's capacity and spillway, both of which will undergo changes in 2019-20, including the construction of a temporary "cofferdam" to allow work to occur.
The $90million project will also include installation of a labyrinth spillway, which will see water spill over its saw-teeth down into Six Mile Creek in a more controlled way.
Detailed design on the project is under way this year, a Seqwater spokeswoman said.
"This phase of the project will involve further site investigations, refining the design, investigating construction methodologies, regulatory approvals and procurement," she said.
"Seqwater has begun the process of obtaining the necessary environmental and regulatory approvals and is talking with neighbours and the broader community about the upgrade and potential impacts.
"[It] will develop a report investigating the potential impacts of the project including on the environmental values of Six Mile Creek."
To reduce the safety risks during construction, the water level will need to be temporarily lowered, the spokeswoman said, "involving removing the existing embankment and spillway, strengthening the foundation down to the underlying bedrock, reconstructing the dam walls and building [the] labyrinth spillway".
Community Reference Group member, local resident Greg Clareburt, said he was told the lake would ultimately look no different after the work, "but during the construction phase the water level will be substantially reduced, rendering the lake unusable for recreational activities".
Mr Clareburt said both the cofferdam and main works would require substantial fill.