Desalination plant instead of dam?
A DESALINATION plant on the Northern Rivers coast-line could be used to secure the region’s water supply as the local population explodes by about 70,000 people over the next 26 years.
Rous Water technical services director Wayne Franklin said a desalination plant was one of the options Rous Water would explore as it looked for alternatives to the expensive and politically difficult plan to build a new dam at Dunoon.
Rous Water is pressing ahead with the Dunoon dam plan for the moment. However, Mr Franklin said there were no guarantees the dam, which had featured at the centre of Rous’ plans for the region’s future water supply since 1995, would ever be built.
Environmental assessments for the 50-billion litre dam (Rocky Creek, the region’s current mainstay, holds only 14 billion litres) were not complete and could yet rule it out of contention, he said.
At the same time, public and political opinion had tilted against dams – as the Queensland Government discovered when Federal Environment Minister Peter Garrett ruled against the Traveston Dam last year.
Mr Franklin said the cost of a new dam which, on current prices could hit $200 million, was also beyond the current reach of the community, particularly while Rous recovered from the $40 million spent on its project to draw water from the Wilsons River near Lismore.
Rous had rechristened the Dunoon Dam Project as the Future Water Strategy, brought in a community-based project reference group and completely changed the project’s focus.
“Rous Water has resolved to continue with the Dunoon Dam so we can build it if and when we need it, but at the same time we’re doing everything else we can to avoid building it,” Mr Franklin said.
That meant encouraging strategies to delay the need for a new major water supply. Those measures are working. Policies ranging from Lismore City Council’s ‘odds and evens’ rule to control water usage; to Ballina Shire Council’s grey water reuse policy in new housing developments;to the State Government’sBASIX rules requiring new homes to include a water tank, had combined to reduce the amount of water used per person on the Northern Rivers.
However, a new secure water supply will still be needed eventually – even if that comes well after Dunoon’s original 2020 construction date – and that is where the Future Water Strategy and the reference group comes in.
The group’s job is to discuss anything and everything that might protect the region’swater supply. So far the options raised have ranged from a ban on new residents coming to the region to a plan to harvest stormwater from urban drains during downpours.
The group had not yet discussed desalination, but the option was on the table and had some strong benefits, Mr Franklin said.
On the plus side of the ledger, Mr Franklin said a desal plant could be turned on and off at will, depending on the region’s water needs; it could be built in modules, each of which would provide the equivalent of one-third the amount of water taken from Rocky Creek Dam each year; and it would be much cheaper than building a new dam.
On the negative side, the plants used an enormous amount of energy, which meant higher running costs and a still great, if different, environmental impact.
While no real thought had been given to the location of a desalination plant, Mr Franklin said it was easiest to draw water from estuaries – which would likely place the plant near the mouths of the Richmond or Brunswick rivers.
But estuaries could also have water quality problems, particularly during and after floods when rubbish was washed into the estuaries.
Drawing water from the ocean or Byron Bay meant cleaner water, but also a longer pipe from the drawing point to the desalination plant onshore, which meant greater engineering problems building the plant and a higher cost to the project.