Buller mayor offers Westport's dredge to help fix Kaikoura harbour's seabed uplift problem

By Lee Scanlon

Kaikoura's quakes may provide an opportunity for Westport's dredge Kawatiri, which has been underused since Holcim left Westport and dredging of the port stopped. Photo / Westport harbour
Kaikoura's quakes may provide an opportunity for Westport's dredge Kawatiri, which has been underused since Holcim left Westport and dredging of the port stopped. Photo / Westport harbour

Kaikoura's quakes may provide an opportunity for Westport's dredge.

The Kaikoura harbour needs dredging and Buller Mayor Garry Howard said Buller Holdings Ltd would be exploring the opportunity.

"It's certainly just an avenue to explore and see how suitable it is."

Westport's dredge Kawatiri has been underused since Holcim left Westport and dredging of the port stopped.

Buller Holdings chief executive Stephen Lowe said Buller could help Kaikoura if a suction dredge would fit the bill, but he would need to find out more.

Westport harbour's website describes the Kawatiri as having a team of highly qualified and skilled mariners.

It says the Kawatiri dredges the Buller River and bar, also offering outport dredging.

The Kawatiri has in recent years undertaken regular work at Nelson, and previously also performed work at Greymouth and Gisborne.

The 55m twin-screw 915 gross tonne Kawatiri has a loaded draft of 4.1m, is capable of trailing suction dredging to a depth of 10.5m, with grab dredging to 15m.

The ship has a 200 BHP bow thruster and a hopper capacity of 635m3.

Northern Buller coastal erosion

What to do about sea erosion threatening northern Buller was thrashed out at a public meeting at Ngakawau tonight.

About 60 people, including council representatives and NIWA experts, attended the meeting to discuss protection for seaside Granity, Ngakawau and Hector properties.

The mostly amicable discussion was a sharp contrast to a fiery meeting in the same hall last month over Ngakawau/Hector's water supply.

After more than two hours - much of which was taken up with questions - the residents agreed to work with the West Coast Regional Council (WCRC) on the best sea erosion protection for their individual circumstances.

Similarly threatened properties will form groups and WCRC engineer Paulette Birchfield will come up with costs to protect their properties.

The council will set up several special rating areas to pay for the work.

The priority will be two Granity areas. One extends 850 metres from Chair Rock (141 Torea Street, Granity) to Lovers Rock (165 Torea Street, Granity). The other extends 780 metres from Lovers Rock to the southern limit of Merret's wall (14 Main Road, Ngakawau).

NIWA scientist Dr Murray Hicks and NIWA coastal engineer Mike Allis told the meeting northern Buller beaches were suffering from a lack of sediment.

"There's nothing particularly rosy coming up in the future for this Coast, unless of course you get a very big earthquake - then you will get a lot of sediment, but you will have other problems," Dr Hicks said.

He and Mr Allis both said groynes were not the answer because sediment built up on one side and the beach on the other side eroded more.

Mr Allis said an effective groyne field might require a groyne for every two properties. "That would be 100 groynes ... personally I think that's quite ugly." He said all protection options cost money. The "gold-plated option" - a rockwall similar to Punakaiki's - could be very expensive.

Residents could do other things, such as plantings, to buy time but the only long-term solution was moving further from the sea, Mr Allis said.

One man said the sea had already been into local houses. Some sections were now useless, but people still had to pay rates on them.

Another said ratepayers at the northern end of Hector had spent about $5000 each 10 years ago putting in their own rock walls which had worked well.

Mr Allis advised against "little bits of inconsistent, incoherent seawalls", because waves would wrap around the sides of them.

Buller District councillor Emily Miazga asked whether the New Zealand Transport Authority would help fund work to protect the state highway.

WCRC chief executive Mike Meehan said the authority had only $3 million for preventative maintenance nationwide and was taking a reactionary approach. "They wait until the issue is right at their doorstep." A woman said the WCRC had told residents at the northern end of Granity that a small rockwall would cost about $35,000 per ratepayer.

She asked whether a group of homes could save money by getting one resource consent, rather than individual consents, for the protection work.

Mr Meehan said they could, but consents were not the major cost. "The big cost is going to be the physical works." He noted that the Punakaiki seawall had cost $400,000, but using substandard rock had pushed yearly maintenance costs to about $100,000.

Regional councillor Terry Archer said six of the 12 sections of the Granity-Ngakawau-Hector coastline identified by the NIWA report already had satisfactory protection. The other residents would have to decide what they wanted. The council was happy to work through the issues with them.

"We are all realists and understand that for some people there may be huge financial issues to achieve those outcomes." Mr Meehan said the WCRC didn't believe one rating district was an option because each segment of the coastline had different issues. "We think the better way forward is to work with those communities." The council liked to have 70 percent of ratepayers in a rating district in favour before it proceeded with any protection option, he said. Ms Birchfield would liaise with ratepayers on options and costs.

A woman said the WCRC had taken too long to do anything. The coastline had suffered major damage in the interim.

Mr Meehan replied: "We can only apologise for that and commit to doing this quickly."

- Westport News

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