Heathcote buyout a possibility

The Christchurch City Council could end up buying up numerous properties along the banks of the Heathcote River as it tries to find a way to deal with ongoing flooding problems.

Staff will meet with residents this week to outline a range of flood mitigation options, which will be presented to city councillors in a report next month.

Options include dredging, construction of small stopbanks, bank stabilisation, storage work and use of the council’s flood-intervention policy.

The policy has previously been used to buy flood-prone houses in the Flockton Basin.

Residents living along parts of the Heathcote River have put up with flooding for years. Several properties were inundated with water during a storm in July, including 13 homes that flooded above floor level.

Yesterday, council drainage manager Keith Davison estimated between 25 and 35 riverside properties could be eligible for attention under the flood-intervention policy.

The policy involved working with homeowners to determine the best option for their property – such as reducing flood risk through localised drainage or house raising.

The council may offer to buy the property. Purchase offers were voluntary.

Davison said the council had established it was ‘‘very difficult’’ to protect all houses in the area with civil engineering structures.

‘‘We can turn to the established policy council already has . . . the policy that was applied in the Flockton area already, where we had options to look at protecting the most at-risk properties that weren’t going to benefit from the Flockton bypass and creek works.

‘‘At that point we actually ended up giving purchase offers on a voluntary basis to residents,’’ Davison said.

Last year it was announced ratepayers would spent about $2.5 million buying seven Flockton Basin properties.

‘‘With Heathcote, again we still have that policy available to us [and] at this stage we’re looking to put that policy back in front of council just to do a few little minor tweaks. At this point we haven’t even got council agreement to go out to talk to anyone who might be eligible,’’ Davison said.

Homeowners still vulnerable after other flood-mitigation

‘‘Different people will flood in different events and different people will benefit from the proposals . . .’’

CCC land drainage manager Keith Davison

proposals were agreed could be eligible under the policy, Davison said.

Council staff had put together a ‘‘core number of projects and options’’ that could reduce flood risk along the Heathcote River.

‘‘We’ve looked at stop-banking on the Heathcote . . . to protect against the severe flood events, the really big storms, the once-in-a generation-type storms. They’re not really very practical – they would be around about two metres tall.

‘‘If you’re a resident there, you wouldn’t be able to see the river any more because the stopbank would be in the way.

‘‘It would be so big that the road would have to sit on top of the stopbank and it would create all sorts of problems and issues,’’ Davison said.

The council would explain to residents why stopbanks were not ‘‘particularly practical’’ to protect against severe storms.

‘‘It’s not one that we feel . . . we would be proposing or recommending to council at this stage.

‘‘Stop-banking itself is still something that potentially . . . we could do, but low stopbanks,’’ Davison said.

Low stopbanks would protect against more frequent flooding.

‘‘There would be a whole bunch of design considerations we’d have to consult on, but it’s not an option that we want to dismiss at this stage,’’ he said.

Meanwhile, the council was already engaged in upper Heathcote storage projects – basins and dam areas – to stop the lower Heathcote being swamped.

Dredging of the Woolston Cut had also been approved, as had funding for bank stabilisation work. ‘‘Dredging is something that is definitely back on the cards again,’’ Davison said.