Alkimos desalination testing

Early investigations to consider possible future Perth seawater desalination plants will take to the water this month, as an offshore survey begins in Alkimos.

The surveys are being completed as part of feasibility studies under way into a possible seawater desalination plant in the area, which is being considered as a potential future water source for Perth.

A possible second desalination plant for Kwinana is also being investigated, as well as other climate-independent sources.

The Alkimos testing will begin on or about September 17, initially with three weeks of seismic testing, followed by core-sampling of the seabed utilising a drilling barge that may be visible from the coast. The seismic testing will involve an exclusion area being off-limits to vessels and equipment to prevent entanglement (see map below).

The seismic testing, which is non-invasive, involves collecting data from the seabed and subsurface geology through releasing pulses or sound waves.

Once complete it will be followed by five weeks of core-sampling which will involve drilling small holes into the seabed and extracting samples for analysis. During this second stage, the exclusion zone will be smaller, extending 25m around the barge and clearly marked by four flashing yellow buoys.

Surveys are planned to be complete in November.

The work will provide information about the seafloor and geology beneath the seabed, which will inform safety, environmental and construction considerations for offshore components of the possible new desalination plant.

The testing will be in waters directly off Alkimos between Alkimos Reef and Eglinton Rocks and extending out from the coast about 5.5 kilometres. A notice to mariners will be issued with full details for vessel owners and operators.  The public will retain access at all times to Alkimos Beach for fishing and swimming and it will be safe to dive at the nearby Alkimos and Eglinton wrecks during the work.

The work will continue seven days a week depending upon weather and is expected to be completed by mid-November. Boaters are asked to remove all fishing equipment from the area by no later than  September 16 and adhere to the exclusion zones or avoid the area where possible.

If constructed, the seawater desalination plant would form part of the metropolitan area’s Integrated Water Supply Scheme and predominantly service the city’s growing northern corridor.

The Perth metropolitan area already has two operating desalination plants - at Kwinana and Binningup – which together supply 48% of Perth’s fresh water needs. Desalination is a climate independent water source that doesn’t depend on rain.

An Alkimos desalination plant would be located next to existing wastewater treatment infrastructure, within the Alkimos Water Precinct. No decision has been taken at this time to proceed with construction or when a new water source may be needed for Perth.

Members of the community are invited to learn more about the desalination plant feasibility investigations and give feedback at www.watercorporation.com.au/securingsupply.