EP desal construction progresses as tough granite rock slows marine tunnelling

Major construction work is underway on the Eyre Peninsula’s new desalination plant, but with hard underground granite rock slowing down marine tunnelling, SA Water is now forecasting a change to the project’s first water milestone.

As part of constructing a 440-metre-long underground tunnel to house the plant’s marine infrastructure, the 60-tonne tunnel boring machine (TBM) has encountered significantly challenging geological conditions as it gradually moves below the seafloor off Billy Lights Point.

The plant, which will produce up to 5.3 gigalitres of desalinated drinking water to around 35,000 homes and businesses on the Eyre Peninsula, has previously been forecast to deliver first water by the end of 2026.

The plant construction has continued to make positive progress including the recent construction and testing of a new 7-kilometre-long drinking water transfer pipeline connecting the new plant to the region’s existing drinking water network, and major extension works to the local electricity network.

SA Water Chief Executive David Ryan said around 80 per cent of the tunnel is already complete, but geological challenges have impacted the machine’s rate of productivity.

“We completed comprehensive geotechnical analysis and borehole sampling as part of the project’s design, but the density of incredibly hard layers of granite rock below the seafloor is greater than expected and has significantly slowed our tunnelling progress,” David said.

“Based off the sequential nature of the marine construction activities, the project’s initially-forecast first water target of late 2026 will need to be revised.

“We recognise this is a critically important project to secure the Eyre Peninsula’s long-term drinking water security, and we assure the community we are working to complete the plant’s construction as quickly and safely as possible.

“We are continuing to closely monitor the TBM’s rate of progress over the coming weeks as it advances through the remaining granite rock environment to understand the overall changes to the first water schedule.

“We are also actively working with our marine contract partner to optimise the machine’s progress where we can, including adjusting the machine’s cutting disc used to drill through the surface, and sourcing additional tunneling support workers to ramp-up the tunneling schedule.”

The revised project timeframe is not expected to negatively impact the region’s drinking water security or see the need to introduce water restrictions, with SA Water’s groundwater allocation for 2026-27 sufficient to meet current customer demands until the desalination plant is operational.

For more information on the Eyre Peninsula desalination project, visit watertalks.sawater.com.au.

Contact:

Phone:

Email: