The Alkimos seawater desalination plant has reached a major milestone, transitioning from land‑based works to offshore tunnelling.
Two giant tunnel boring machines (TBMs) – each over 4m in diameter and longer than a football field – started their undersea mission.
The machines will carve two subterranean pipelines over the next 12–18 months, carving a 2.5km intake tunnel to draw in seawater, and a separate 4km outfall tunnel to return concentrated brine. Advanced technology will ensure minimal impact on dunes, beaches, and marine habitats.
Continuing a long‑standing TBM tradition, the machines have been named. The intake TBM is now Mary, inspired by Mary the Prophetess, an alchemist famed for purifying liquids. The outfall TBM is Karli, derived from the Whadjuk Noongar word for “boomerang,” acknowledging local Indigenous connections to the land.
The $2.8 billion project is Western Australia’s largest seawater desalination initiative. Once complete, it’s set to deliver 50 billion litres of drinking water annually, helping meet the needs of over 2.5 million people while reducing reliance on climate‑stressed groundwater.
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