Work is underway on a new dam wall as part of a major scheme to secure water supply for South-East Queensland.
Activity has started on the foundations of the structure at Lake Macdonald, west of Noosa, after the successful demolition of the old wall and spillway.
An Seqwater spokesperson said the initiative was crucial.
“Construction is progressing on the Lake Macdonald Dam Improvement Project to ensure the dam meets modern engineering and design standards and continues to operate safely and provide water security for generations to come,” they said.
“The project is expected to be an investment of approximately $500 million into enhancing dam safety and local water security (and) will support more than 150 jobs during construction.”
Construction is expected to be completed in late 2029, subject to weather and site conditions.
The new dam wall foundations will start with the installation of secant piles: deep interlocking concrete columns that form a stable underground retaining wall structure and allow excavation down to rock foundations.
Major works will then focus on large concrete pours to construct a new split-level spillway, along with rebuilding the embankments, and installation of new outlet and downstream protection structures.
Machinery and equipment used will include piling rigs, excavators, concrete trucks and equipment, cranes, trucks, light vehicles and hand tools.
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The original dam was constructed in 1965 and was raised in 1980.
The upgraded dam will feature a modern split-level concrete spillway, including a lower ogee crest (the curved edge that water flows over) aligned with the original lake level, and an upper labyrinth spillway designed to safely manage higher flows during major rainfall events.
Workers recently reached a major milestone when they demolished the old wall and spillway. While 15 days of continuous work was originally planned, demolition of the existing spillway and embankments was completed in 12 days, three days ahead of schedule through carefully planned operations, adapting to local weather conditions as required.
Significant rain in March had previously required the program to be rescheduled to ensure works could be carried out safely.
Seqwater issued a project update in June stating that the water provider and construction company John Holland “prioritised minimising impacts (during the demolition), with specialist crews monitoring site conditions and environmental controls around the clock and maintaining regular communication with local residents”.
Seqwater said locals could be affected during the construction of the new wall.
“While mitigation measures will be in place and every effort will be made to minimise impacts on the community and environment, local residents may experience some noise, dust and vibration associated with this work.”
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