Council rejects new protection options for West Coast town devastated by winter floods

Tuesday, 31 August 2021

At the mercy of alpine rain, will the Buller River deliver a large flooding event to the West Coast town of Westport? (First published May 22, 2020)

An expert report has criticised a multimillion-dollar West Coast Regional Council plan for Westport flood protection as being no better than doing nothing.

The regional council’s proposals, which are out for public consultation as part of its long-term plan, include a $3.4 million option that would include the building of a flood wall along the Buller River at Westport and partial stop banks around the town.

The options were in the planning stages when the town was inundated with floods on July 17 and 18 that forced more than 2000 of its 4500-odd residents to evacuate and left more than 460 homes damaged.

In its submission the Buller District Council says it has “major concerns” about the proposal because it does not take into climate change into account or the river flows in a one-in-100 year event.

**READ MORE:

Westport township after floodwaters inundated the area in July.

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* Data will help predict severity of future flooding - and how to mitigate it

The Buller District Council is calling for its regional counterpart to abandon its plan for flood walls and stop banks alone and come up with better long-term solutions that include raising building platforms and floor levels as well as abandoning some land and relocating residents.

It says the July floods were an event more akin to a one-in-40 year event.

A second $10.2m option – preferred by the council’s river engineers – includes stop bank and flood wall protection around the whole town, including the Orowaiti Lagoon and Snodgrass Rd, which has been flooded twice in three years.

However, the Buller District Council’s submission says ring-fencing the town would have significant risks outweighing the benefits.

“We have taken expert advice and have significant questions as to the design standard and appropriateness of the particular solutions proposed,” it says.

The July floods left 70 homes left red-stickered while another 393 homes were yellow-stickered.

It commissioned a review by Tonkin & Taylor, which says the regional council’s $3.4m option appeared “no better in preventing property damage than the ‘do nothing’ option”.

It says the regional council’s proposals would only protect the town in a one-in-20 year flood event.

It also says more site investigation and survey work is needed because the land on which the flood walls would be built are at risk of liquefaction.

Buller District mayor Jamie Cleine said the $3.4m option would be costly and did not factor in important issues such as the effects of climate change.

“It is essential that we get this right. We need a long-term solution that enhances the community and provides the security for continued investment in Westport.”

The Tonkin & Taylor report also included modelling by consultancies Land River Sea and River Edge Consulting, which showed the regional council did not address projected rise in the flow of the Buller River, sea level rise, debris under bridges, earthquakes, liquefaction and storm water.

“In fact, the information shows that with the significant flows that came into Westport via the Orowaiti River, the proposed option would have done little if anything to stop the damage that occurred in the July flood,” it said.

The report says the flood walls and stop banks would need to be higher than currently proposed and would cost more.

The regional council’s flood protection plan would have done little to help the town in the July event.

Cleine said the Buller council wanted a new plan to include proposals “such as raising building platforms and, crucially, whether some areas of the town remain suitable for housing”.

“It is important that we talk to the community about any proposed options.

“It is ratepayers that will be footing the bill for flood protection works and it is essential they are consulted and that the chosen package meets community needs.”

The council’s submission called for the regional council to do further modelling, and work with the council and the community to draw up new options for consultation in 2022.

A regional council spokeswoman said the submission had been received and would be considered as part of the long-term plan and its district plan.

“There is considerable overlap in the submission with work going on in Te Tai o Poutini Plan,” she said.