Reservoir breach likely cause of silty torrent

Wānaka homeowner Sam Smoothy stands in front of his Wineberry Lane property, where rushing silt...
Wānaka homeowner Sam Smoothy stands in front of his Wineberry Lane property, where rushing silt water from a nearby development came within 5cm of getting inside yesterday morning. PHOTO: REGAN HARRIS
At least one home was damaged and five other properties threatened by silt water surging from a neighbouring development site in Wānaka.

Fire crews were alerted shortly before 9am yesterday to flooding at a property on Mount Roy Tce, which sits downhill from a large silt water reservoir on the site of a planned 354-lot residential subdivision.

A Fire and Emergency New Zealand spokesperson said one house had flood damage. Crews had taken steps to prevent any additional properties from being affected.

A homeowner in neighbouring Wineberry Lane, Sam Smoothy, said he woke shortly after 9am to find water surrounding his house and rising rapidly.

"It was all pretty hectic."

He watched with concern as the rushing water came up to his house, stopping within 5cm of the home.

A friend later arrived with a digger to create drainage channels and direct the water away from his property.

Mr Smoothy said he understood contractors were trying to release excess water from the reservoir in a controlled manner when things went wrong.

A contractor from the development visited him in the afternoon and informed him the water surge was likely the result of a breach in the reservoir’s wall.

While he appreciated the company’s efforts to keep homeowners updated, he could not understand why there had been no attempt at communication earlier in the day when it was clear the water was heading where it shouldn’t.

"The interesting thing for me is that even if it’s a controlled release, why didn’t they go downstream and warn anybody?

"Where did they think that pile of water was going to go?"

John MacKay, managing director of Benchmark Construction and the primary contractor on the development site, told the Otago Daily Times the surge of water was due to an unexpected breach of the reservoir.

"There’s been a burst in the actual dam wall that has released the volume of water that’s caused the damage."

In a statement, a Queenstown Lakes District Council spokesperson said the flooding incident appeared to be related to ‘‘a failure of erosion and sediment controls" on a private property after heavy rain overnight.

"The property owner, council contractors and emergency services have worked to prevent any further flooding and pump water from affected properties."

The spokesperson said the council’s monitoring and enforcement team were investigating the incident and could not offer any further comment until the investigation ended.