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Plans to divert wastewater into the Kaikorai Stream will have an environmental impact but are outweighed by the benefits to human health and wellbeing, a city council manager says.
The Dunedin City Council announced ahead of a public information session in South Dunedin yesterday it is investigating the possibility of diverting wastewater into the stream during heavy rain.
Wastewater from the Kaikorai Valley catchment area at present is piped through South Dunedin to the Tahuna treatment plant.
If a resource consent is granted by the Otago Regional Council, the plan would help prevent wastewater from being discharged into private property or roads in South Dunedin.
Council 3 Waters group manager Tom Dyer said the council understood discharging a large amount of wastewater, diluted and screened, into a stream would have an impact on the environment.
But with a long-term solution to the repeated contamination events in South Dunedin still up to eight years away, the health and wellbeing of residents needed to take priority, Mr Dyer said.
An overflow already existed on the stream and in other parts of the city, but not at the same scale as the one now being investigated, he said.
As the plans were only at an early stage there was no cost estimate yet.
The council hoped the scheme could be in place by winter next year, he said.
Margaret Waide, a resident of flood-prone Surrey St, said the proposal was wonderful and would greatly benefit residents on the street whose homes had been flooded numerous times.
Earlier this year, Mrs Waide presented a petition signed by about 30 residents of Surrey St asking the council to give urgent attention to repeated wastewater flooding in the area.
''We've been listened to and it's just fabulous news. It's a great relief to me and my neighbours and we do have to thank the council for that.''
Greater South Dunedin Action Group president Ray Macleod said the council had listened to the concerns of residents and deserved recognition for that.
''I think it's a great outcome and it shows our concerns have been listened to, and it's not a perfect solution but it's what is needed in the short term.''
Otago Fish and Game spokesman Niall Watson said sending wastewater into a stream was never ideal but in this instance he could understand the reasons behind the plan.
The ecological impact of the wastewater would depend on how treated it was, and Mr Watson said he hoped both the city council and the regional council would keep that in mind while the consent was processed.
''It's not an immediately attractive proposition but we do understand the motivation and the importance of alleviating the flooding in South Dunedin.''
Previous wastewater flooding in South Dunedin had been unscreened. Much of it ended up in the stormwater system via mud tanks and eventually in the Otago Harbour, Mr Dyer said.