Offshore testing for future desalination plant at Alkimos extended

A drilling barge has been testing for a potential desalination plant off Alkimos since September.
A drilling barge has been testing for a potential desalination plant off Alkimos since September.

UNFAVOURABLE weather conditions have prolonged investigations for a desalination plant off Alkimos.

Water Corporation started the offshore investigation last September, which was originally expected to take three months, but the drilling barge remains off the coast.

MORE: Desalination on hold, State looks at recycling water

Media and strategic communications manager Clare Lugar said the work would provide “valuable information about the seafloor and geology beneath the seabed”.

“(It) has experienced some delays due to unfavourable weather conditions, but is expected to be completed in the coming weeks,” she said.

“Costs and timeframes in relation to construction and operations will be considered closer to when the new plant is needed.

“No decision has been taken at this time to proceed with construction or when a new water source may be needed for Perth.

“A new desalination plant in either Alkimos or Kwinana may not be needed for many years, but now is the right time for us to do some early community consultation and technical investigations.

“The feasibility investigations have focused on a 25 billion litres per year capacity seawater desalination plant, with future expansions of 25 billion litres to follow to an ultimate capacity of 100 billion litres of drinking water a year.”

Ms Lugar said the size of the Alkimos wastewater treatment plant, which treats about 20 million litres a day, meant groundwater replenishment was not a practical option as a water source.

“Over the longer-term, our aim is to have about one-third of Perth’s metropolitan water being recycled through groundwater replenishment,” she said.

“Over the next few years we will undertake studies to determine how groundwater replenishment may be expanded to other large wastewater treatment plants.”

Water Corporation has finished building recharge bores in Wanneroo and Neerabup and expects to finish the 13km pipeline connecting the bores to the advanced water recycling plant in Craigie by July.

“Up to 14 billion litres of recycled water will be recharged as part of the project, which will double the capacity of stage 1 of the Groundwater Replenishment Scheme to up to 28 billion litres of drinking water a year,” Ms Lugar said.

“Groundwater replenishment is an innovative concept where treated wastewater is further treated to drinking water standards, and recharged into our groundwater supplies to be stored until it is needed.

“It doesn’t rely on rainfall and recycles large volumes of water sustainably.”