Foul odours and polluted swimming sites and wetlands are becoming commonplace in parts of the Georges River catchment, with a dozen sewage discharge points operating in excess of licensed levels.
To limit the impact of the overflows, Sydney Water is seeking approval from the NSW Environment Protection Authority to ease some of its long-term discharge targets.
The EPA, which licenses Sydney Water, sets a goal of 40 overflow events per decade for the Georges River. That level is currently being exceeded at 12 of the 727 overflow points in the Georges River.
Sydney Water said average discharges of waste water at those dozen sites were 10 megalitres, or equal to about four Olympic-sized swimming pools.
The overflow points are designed to release excess wastewater and stormwater during heavy rain to prevent it backing up into homes and offices.
Sydney Water cut spending on overflow abatement by 37 per cent this year to $35 million but expects to increase it next year. The authority last week revealed a 13 per cent increase in annual profit to $415 million for the 2012-13 year and boosted its dividend to the O’Farrell government to $291 million.
The health of the Georges River has become a focus after a flash flood on November 22 overwhelmed pumps at Glenfield Wastewater Treatment Plant. About 150 megalitres of untreated wastewater entered the river, prompting NSW Health to warn against contact with the water all the way down to Botany Bay.
Sydney Water managing director Kevin Young met EPA chief Barry Bouffier prior to the Glenfield failure to discuss modifying the overflow targets on the river.
”We’re working with the EPA to move off that target of 40 in 10 [years],” Sydney Water strategy manager Rod Kerr said. The corporation wants the focus to shift to the impact of the discharges rather than their number.
One option would be to divert discharges so that more of them occur further along the main sewer line into the Cooks River or east of Sydney Airport, where tidal movements allow for easier dispersal.
One discharge point on the Cooks River itself has had 217 discharge events over the decade - or more than five times the goal - with each averaging 12 megalitres, Sydney Water said.
”The EPA will thoroughly review any proposals from Sydney Water but would only agree to changes that resulted in an improvement in the environment,” the EPA’s chief environmental regulator, Mark Gifford said.
Mr Bouffier said the authority was ”a fair way away” from a decision, with more data needed.
”What are the overflows that produce big impacts on the environment?” he said. ”It would be nice if we can come up with something a bit more sophisticated than just a number [of discharges]?”
Secretary of Georges River Environmental Alliance, Sharyn Cullis said some sites discharging below the 40-in-10-year target also need urgent attention, such as the Dairy Creek overflow into the Lime Kiln Bay wetlands.
“This is not a long-term solution,” said Ms Cullis. “We don’t actually want to see it just shifted so it’s going to affect somebody else’s backyard.”
Sydney Water, though, said investments in the Georges River had improved conditions in the region, and the past decade had contained more heavy rainfall events than the longer-term average.
“We’re picking a period of time when it’s been uncharacteristically wet and saying, ‘wow, look, the performance of the system is cactus’,” Sydney Water’s Mr Kerr said. “The reality is, it’s not that bad.”
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