Staff grilled over flood defences

Andrew Simms
Andrew Simms
Otago Regional Council senior staff have been left in no doubt residents on the Taieri Plain will not take kindly to any lack of urgency to maintain flood defences.

Staff received something of a grilling at a Mosgiel-Taieri Community Board meeting last night, particularly from board chairman Andrew Simms.

This followed the release of a risk assessment about floodbanks that showed a major flood could have widespread consequences and places such as Dunedin Airport looked especially vulnerable.

Mr Simms described the impact of the report by Tonkin + Taylor Ltd as like pouring petrol on a fire.

Vulnerability to flooding was one of the biggest issues facing the Taieri, and Dunedin, and the report demonstrated Dunedin Airport might one day be "washed into Lake Waihola", he said.

Residents were concerned about risks for their own properties and a perceived lack of urgency in dealing with the situation, he said.

The regional council was represented at the meeting by engineering manager Michelle Mifflin, operations general manager Gavin Palmer and natural hazards manager Jean-Luc Payan.

Ms Mifflin said the analysis was aimed at getting a better understanding of what was most likely to happen in a scenario where floodbanks were breached.

The airport had its own controls and some potential challenges were simply down to its location, she said.

"This is not new for them.

"They understand this risk."

The report was based on the estimated performances of floodbanks in a flood comparable to the one in June 1980, which caused devastation across the Taieri Plain and closed Dunedin Airport for 52 days.

Council staff estimated there was a 26% chance of such a flood happening in the next 30 years and a 40% chance in the next 50 years, based on today’s climate patterns.

The lower Taieri flood control scheme has floodbanks that run for 109km and about 400m was identified as extreme risk, 15% very high risk and 47% high risk.

Planning was under way to deal with the two sections of floodbank identified as extreme risk, the council said.

All remaining sections of the floodbanks would be investigated and the priority would depend on their risk ratings.