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The Dunedin City Council is investigating a short-term measure to help prevent wastewater flooding in South Dunedin.
During heavy rain, wastewater flooding often occurs in South Dunedin, particularly in the Surrey Street/Hillside area, when the volume of water entering the wastewater system exceeds its capacity.
3 Waters group manager Tom Dyer says the council is already planning to address this issue through major projects, which will see wastewater from the Kaikorai Valley catchment area – currently piped through South Dunedin to the Tahuna treatment plant – piped to Green Island for treatment instead. While planning is already underway, it will take at least eight years to fully plan, design and construct.
“The South Dunedin community has made it very clear to us that eight years is too long to wait, particularly given the potential health risks that come with wastewater flooding,” Dyer said. “We have listened to their concerns and are looking at an interim measure which, could potentially be in place before next winter.”
Dyer said the interim measure involves diverting a large amount of wastewater away from South Dunedin during heavy rain, by discharging it into the Kaikorai Stream. This method, known as a wastewater overflow, will help avoid wastewater backing up and being discharged on to private property or roads and other places where people are likely to be.
The council will need to apply for resource consent from the Otago regional council for it to go ahead.
“This certainly isn’t intended as a permanent or ideal solution,” Dyer noted. “Clearly, discharging a large amount of wastewater, albeit heavily diluted and screened, into a stream, will have an impact on the environment.
“However, we believe that the benefits to human health and wellbeing far outweigh the environmental impacts in this situation, until the permanent solution has been constructed.”
