water supply

Perth ramps up groundwater replenishment scheme to drought-proof city

water supply
By 2060, one fifth of Perth’s water supply is expected to be replenished groundwater. Photograph: Martin Godwin for the Guardian

Recycled water pumped into underground aquifers as part of plan to make Perth’s water supply ‘climate independent’ by 2022

May 29, 2017 — Perth is pumping recycled water into the underground aquifers that provide its drinking water supply as part of a strategy to drought-proof the city against climate change.

The Environmental Protection Authority (EPA) on Monday approved an application for the Western Australian water authority to double the capacity of its groundwater replenishment scheme, bringing the amount of recycled water pumped into the Gnangara Mound every year to 28 gigalitres.

The most recent proposal would see the Water Corporation build a 12.8km pipeline from a proposed recycled water plant at Beenyup in the northern suburbs to two different aquifer points, where it will be pumped into Leederville and Yarragadee aquifers.

About 14 gigalitres of wastewater per year would be processed and treated to potable standard at the new Beenyup recycled water facility, before being pumped into the aquifers. The same amount of water will extracted from those aquifers every year to be treated again and used as drinking water.

Murdoch University professor of desalination and water treatment, Wendell Ela, said pumping recycled water into the underground system rather than using it directly once it was treated to a potable standard, reduced “the yuk factor”.

“That’s inevitable and it’s not a bad thing because any time we talk about water we should be interested in the water we are getting and the quality we are getting,” Ela told Guardian Australia.

Ela said the aquifer also provided a “very large, very cheap storage tank,” which allowed the water corporation to replenish groundwater at a steady rate but only withdraw water when necessary.

“You want it to essentially be a net zero balance,” he said.

The Water Corporation spokeswoman Clare Lugar said the groundwater replenishment scheme was part of a long-term plan to secure water supplies in response to climate change.

Lugar said the proposal ticked two of the organisation’s three strategies for water security, the third being encouraging people to use less water.

“Groundwater replenishment ticks two of these boxes – increases water recycling and developing a new source,” she said. “It is a climate-independent source of water, and the new plant at Beenyup will have the capacity to supply the same amount of water used by 100,000 homes each year.”

The scheme is part of a project to make Perth’s water supply “climate independent” by 2022. Without intervention, Perth is projected to have a supply gap of 70 gigalitres a year over the next 10 years, the EPA report said.

By 2060, one fifth of Perth’s water supply is expected to be replenished groundwater.

Construction on the project begins in July.


guardian_64  by Calla Wahlquist | The Guardian