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Stormwater management plans are needed, says CDC


Stormwater management plans for the subdivisions are crucial to help mitigate the dangers of flooding in the Taieri Plain, a Dunedin City Council (DCC) hearing panel heard yesterday.

Staff from the Otago Regional Council (ORC) presented their submission to the Second Generation Plan Variation 2 panel, with flood management being the central concern presented.

CRO Policy and Planning Director Anita Dawe said her council broadly supports the DCC’s position on infrastructure and supports the application of new mapped development area overlays (NDMA ) in dezoned areas.

She said it was important for the panel to understand that ORC’s infrastructure was designed for land drainage and flood management, not stormwater.

“For us, one of the advantages of NDMAs is that this stormwater management plan accompanies the request rather than being a condition of consent.”

ORC’s position was that all developments should have a stormwater management plan.

“Right now the rule is to have one where appropriate, we still consider it appropriate.”

ORC’s director of natural hazards, Dr Jean-Luc Payan, presented the panel with a series of photographs illustrating ORC’s network of banks, spillways and ponds in the Taieri plain.

Dr Payan said that although the system was not designed for stormwater, many stormwater outlets still flow into it.

In written evidence he filed before the panel, Dr Payan said land subdivision, use and development impacted stormwater runoff, especially at pristine sites.

In general, such activities would result in increased peak flows, runoff volumes and runoff velocities.

It was important that the stormwater management approach ensures personal safety, minimizes the risk of surface flooding, protects property from flooding, ensures infrastructure resilience and minimizes the negative environmental effects of stormwater runoff, and this, for probable future climatic conditions.

The hearing will resume at 10 a.m. this morning for the right of reply from the DCC assessors.

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