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THE only solution to polluting ocean waters with pumped treated sewage is to ban the practice, say critics.
About 120 billion litres of class C water is discharged each year under Environment Protection Authority licence from the Eastern Treatment Plant in Carrum into the ocean at Gunnamatta. This effluent is predominantly domestic waste but also contains about 15-20 per cent industrial waste.
Surfers, environmentalists and politicians have been campaigning for more than a decade to have the outfall closed because of its effects on the health of surfers and the marine environment.
Class C, or secondary standard water, is created by treating effluent by screening and sedimentation to remove litter, grit and sludge, followed by biological treatment and disinfection with chlorine.
Some surfers have complained that the discharge causes ear and throat infections and gastrointestinal illnesses.
A plan to extend the pipeline in the hope it would improve conditions was scrapped in 2009 after trials showed that upgrading the plant to treat sewage to tertiary level would be a better option. This decision has saved about $400 million in project costs.
Tertiary standard (level 1) water is a third stage in the treating process and uses ozone and ultraviolet light to bring it to a level suitable for recycling. A $418 million upgrade of the treatment plant is under way and expected to be completed by the end of this year.
Plant manager Charmaine Quick said the upgrade would not only improve water quality to a tertiary level but also reduce the amount being discharged at Gunnamatta and increase the potential for using recycled water.
"The water authorities have dedicated teams that are pursuing new opportunities for customers to use recycled water that would otherwise be discharged to the ocean," Ms Quick said.
"Current examples include the potential use of class A recycled water for intensive food production within the Bunyip food belt, as well as the non-potable use such as toilet flushing and outdoor use in new development areas."
Long-time campaigner and former member of the Clean Ocean Foundation, James Clark-Kennedy, said the upgrade was a step in the right direction. "But this is not the end game. There has to be a commitment by government to continue to better the situation."
Flinders federal MP Greg Hunt said he was committed to getting the outfall closed. "My commitment to closing the Gunnamatta outfall remains unchanged and undiminished," he said.
"At a broader national level, I am eager to work with state governments over the next decade in having outfalls closed and the water recycled and reused for industry and agriculture right around the country."
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