Plan for harbour breakwater

A finger of rock stretching 100m into Otago Harbour is the key to holding back erosion at Te Rauone Beach, on Otago Peninsula, a resource consent application says.

The application by Port Otago and the residents' group Te Rauone Beach Coast Care Committee was finalised in July last year, but was yet to be filed pending funding from the Dunedin City Council.

A copy was released to the Otago Daily Times yesterday by committee chairman Hoani Langsbury, who is also a resident and Otago Peninsula Community Board member.

It detailed plans for a rock breakwater stretching 97m into the harbour from the northern end of Te Rauone Beach.

It also appeared to back residents' claims wakes from vessels were contributing to erosion in the area.

The application noted the beach was under attack from three types of waves - swells entering the harbour from the northwest, waves caused by southwesterly winds, and those generated by passing vessels.

Waves from vessels "include a surge component that can in some instances take sand offshore from the dunes during high tide", it said.

The breakwater would measure 8.5m wide at the base, 2.5m at the top, and rise above the water by 3m at low tide.

It would shelter the northern end of the beach from swells and the wakes from vessels coming through the harbour mouth, and allow Port Otago to replenish the beach using sand dredged from the harbour channel.

The extra sand would protect the coastline from waves coming from the southwest, as well as from vessels leaving the harbour, it said.

The breakwater would also prevent sand moving north along the beach.

The work would require 3000cu m of rock, take up to three years to complete in stages and might require additional sand replenishment every five to 10 years, the application said.

Port Otago wanted council funding for the $160,000 breakwater, but would meet other costs totalling more than the council's share, Port Otago chief executive Geoff Plunket said.

Talks between the parties were held just over a week ago, but an agreement was yet to be reached and the application had not yet been filed.