Queenstown Lakes District Council (QLDC) will be investigating the significant heavy rain event in Wanaka on Tuesday 22 May resulting in some significant surface flooding in several locations in the town.

QLDC Mayor Jim Boult said the event was very much on the radar for him and fellow councillors.

“It was a reasonably extreme event following heavy rain in the days leading up to it, but the resulting level of surface flooding in some areas leaves some questions that we need to be answered,” he said.

QLDC Chief Engineer Ulrich Glasner confirmed that MetService had issued severe weather warnings on the day of the surface flooding.

“At the peak of the downpour the hourly rainfall was 5.2mm. This was a very heavy event on top of already saturated ground,” Mr Glasner said.

“On the face of it, in this event the performance of some of the stormwater infrastructure did not meet our expectations, particularly in some new developments.”

Whilst developers are required to implement stormwater management measures that meet QLDC’s standards some localised erosion and sedimentation took place across the district and QLDC’s Monitoring & Enforcement team is investigating these matters.

Developers have been contacted and are working well with QLDC to implement appropriate controls to further mitigate erosion and sedimentation affects during these heavy rainfall events.

Compounding the situation was the standard autumn challenge of excess leaves blocking or partially blocking drains.

Mr Glasner supported Mayor Boult’s view that further investigation was warranted. “We have work in progress in some cases but it is possible we need to broaden this consideration,” he said.

The Council acknowledged that some existing stormwater infrastructure in the township had already been identified for upgrade.

ENDS.

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