Exclusive: top water bureaucrat says planning has begun for plant to move from producing 15% of water to 30%

This article is more than 1 year old

This article is more than 1 year old

Sydney’s desalination plant will double in size as the city’s water supply approaches the critical threshold in dam levels.

The top bureaucrat who oversees water in the NSW Department of Planning, Industry and Environment, Jim Bentley, told a Committee for the Economic Development of Australia (Ceda) lunch in Sydney, that planning for the expansion had now begun.

He also said Sydney and other cities needed to be having a discussion about when they would reach Day Zero – the day when they would run out of water, as Cape Town almost did – in order to understand what was happening and to motivate discussions about solutions.

He later clarified that he did not believe Sydney was on the verge of such a scenario.

“I don’t want people to leave here thinking we are at a Cape Town situation, we are far from that. But we could be in that situation in the future,” he said.

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“But there are places in NSW that are somewhat more dire and the government is working with those councils.”

For Sydney, the NSW government has opted for more desalination.

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“We have taken the decision to begin the planning for the expansion of the desalination plant. There will be other schemes for Sydney, for the Hunter and other parts of NSW,” Bentley said.

“I will say the D word”, he said. “We will be investing in dams, we will be investing in desalination, but also we must work on the adaptive side of the equation: efficiency and using the great resource that is now called waste water.”

The decision on more desalination plants comes as the prime minister, Scott Morrison, prepares to make a major announcement about additional funding for dams.

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Funding for a list of dams in drought-affected communities was revealed by Nine News on Tuesday night, including the Mole River dam on the border of NSW and Queensland, Dungowan near Tamworth, and Wyangala in central-west NSW.

Morrison will also announce $16m in funding for “managed aquifer recharge” to boost the supply of water in Dubbo, Cobar and Nyngan. This is similar to Perth, where purified wastewater is put back into the aquifer before being extracted for town supplies.

The go-ahead for the expansion of the desalination plant in Sydney had been given “in anticipation that water shortages will become the norm in the expanding city,” Bentley said.

The current desalination plant is now producing 15% of Sydney’s water supply, or 250m litres a day. The plan is to double the plant, to provide 30% of Sydney’s water.

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Sufficient intake piping is already in place for the expanded plant and the site prepared, which should allow a swift build of the additional structure to house the new plant.

Bentley also flagged the need for further community discussion about using waste water as either potable water or a secondary source of water through additional pipes to new houses.

Putting recycled water directly into the dam system proved a bridge too far for the Carr government when it considered options to deal with the last drought. It opted for desalination instead.

However, a number of cities now recycle their sewage into the drinking water system, usually diluted in dams and rivers first, including California, Singapore and London.

Perth injects it back into the aquifer before reuse.

Kevin Werksman, global water markets leader at engineering consultancy Aurecon, said paleontological records showed that it was possible to have 30-year droughts, which is why recycling needed to be considered.

He said treating waste water to drinking standard was one third to 50% cheaper than desalination.

Bentley said reuse needed to be discussed with the community and did not necessarily mean putting it into the drinking water supply.

He said recycled water could potentially be used to achieve the goal of growing a million more trees in Sydney to reduce the “heat island” effects of a large city.

The managing director of South East Water in Victoria, Terry Benson, described how her company was collaborating on a new development, Aquarevo, which uses a community waste-water treatment plant to provide a second source of water to houses.

Each house is also connected to smart technology to allow residents to monitor their water and energy use and the weather. Rainwater tanks empty when it is going to rain significantly in order to double as stormwater reservoirs, she said.