Geotechnical investigation works are underway to improve a decades-old dam.
Water storage provider Sewqater has stated that the Lake Macdonald Dam Improvement Project is progressing.
The upgrade should ensure the dam operates safely and provides water security for years to come.
Seqwater awarded the construction contract to John Holland Queensland in February, and geotechnical investigations have started.
The analysis will confirm the requirements for the project’s temporary cofferdam, which is expected to deliver benefits to the community and environment during construction.
Planning and site preparation works include survey works, water quality testing, installation of project fencing, and engagement with the community and traditional owners.
Seqwater interim CEO Will Harpham said Seqwater was committed to the delivery of the project, to ensure the water source continues to serve the Sunshine Coast well into the future.
“Part of Seqwater’s Dam Improvement Program, the Lake Macdonald Dam Improvement Project will ensure the dam meets modern engineering standards, continues to operate safely during extreme weather events, and provides water security for generations to come,” he said.
“While Lake Macdonald Dam continues to operate safely, dam design and engineering standards, along with knowledge of weather and flood risks, have evolved since the dam was originally constructed in 1965, so this upgrade is about ensuring the longevity of the dam into the future,” he said.
The project involves building a new split-level concrete spillway and upper labyrinth and reconstructing the existing earth embankments.
The project temporary works design, released by Seqwater earlier this year, includes the installation of an upstream cofferdam to keep the lake water level as high as possible for water security, the environment, some recreation activities, and community amenity throughout construction.
Seqwater is working through the construction methodology based on the design.
Major works, including the installation of a temporary cofferdam, are expected to commence next year, after the summer wet season.
The project, which received $71.4 million in state government funding, is expected to support about 150 jobs.
The project webpage outlines fish relocation plans.
“Investigations are underway into the measures needed to manage aquatic fauna at the 42 per cent or 93m reduced water level,” it stated.
“Seqwater will develop a recovery and relocation plan, in consultation with key stakeholders, to manage any aquatic fauna impacted during the lowering and throughout construction.
“It is expected there will be a period when the habitat available for aquatic species, including those of conservation significance such as the Mary River cod, Australian lungfish, Mary River turtle, white-throated snapping turtle, and platypus, is limited.
“To minimise the impacts to these important species, Seqwater is proposing an initial aquatic fauna relocation program.
“We will aim to relocate species of conservation significance before construction begins.
“Some fish are sensitive to handling or changes in water temperature and may suffer injury or mortality if relocated. Therefore, appropriate measures will need to be identified and incorporated into the management approach.
“All relocation will be delivered by expert fish biologists, via a purpose-built fish transport vehicle to Cooloolabin Dam.”
Seqwater told SCN that native fish species will be relocated to Cooloolabin Dam, as it has similar conditions to Lake Macdonald.
Mary River Cod and Australian Lungfish will be left in situ, so they are not disturbed.
During the construction period, water quality monitoring will continue and flows will be maintained downstream in Six Mile Creek. Seqwater and John Holland QLD will also undertake ongoing environmental monitoring throughout the project.
A fishway will be constructed at the Gympie Weir. The location will allow fish and turtles to pass up and down the Mary River, allowing passage between the upper tributaries and reaches to provide better connectivity between Six Mile Creek and the Mary River.
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