North Shore cliff-stabilising seawall: Construction allowed to protect land from erosion

Rubble on the beach at Belmont: owners (above) are allowed to build a new sea wall. Photo / Auckland Council

A new seawall at a North Shore beach can be built to try to stop coastal erosion and protect land at two $13.5m million homes.

Allen and Barbara Peters proposed the 51m-long curved wall at St Leonards Beach, Belmont, beneath two properties they own at adjoining sites between Devonport and Takapuna.

The Peters’ waterfront properties are on Seacliffe Ave and they applied to Auckland Council to build the 3.3m high and 8m wide wall at the bottom of the cliff where there was a collapse in the 1970s, to try to stabilise it.

Because the application was non-complying, it was publicly notified.

Independent hearing commissioners Peter Reaburn, Rebecca Skidmore and Nicki Williams decided last month to allow the scheme, supported by 12 parties, opposed by nine with one party neutral.

The Peters can build the rock masonry seawall with an inbuilt staircase along the coastal margin within the boundaries of their properties and adjoining them.

Allen Peters told the commissioners that he and Barbara had lived at 66 Seacliffe Ave since buying it in 2007 and they bought the neighbouring place in 2015.

A previous owner of 66 Seacliffe Ave tried to build a substantial retaining wall of steel and concrete beams and columns from the Westfield freezing works, which was demolished last century.

The material was stacked at the top of the cliff at 68 Seacliffe Ave in an attempt to stabilise the land.

Around 1972, a storm caused a big slip. The seaward lawns of 66 and 68 Seacliffe Ave collapsed onto the foreshore below. A significant portion of the steel beams and concrete went with them.

Over the years, the Peters had witnessed the steel beams, concrete slabs and steel cables at the bottom of the cliff being increasingly strewn out across the foreshore as tidal forces hit those materials.

The former owners of 66 Seacliffe Ave had planted pōhutukawa on top of the talus, or slip material. Those trees were now 30 years old. But Peters noted that the trees’ root network was becoming increasingly exposed due to ongoing tidal erosion.

Allen Peters said the wall was needed to help protect the cliff toe and earlier slip material from further erosion and retreat, to prevent further soil loss undermining the existing vegetation including the pōhutukawa trees and to avoid increased exposure of the rusting steel beams, cables and concrete rubble and further movement of that debris across the beach.

Peters said the seawall would look much better than the debris and would greatly improve the aesthetic value of the area.

Local resident Chris Glanfield supported the new wall, telling the commissioners seawalls were an important, valuable part of urban environments. He considered the wall would blend well with its surroundings. It was small in the scheme of its context and so would result in little interruption to the environment.

Ruth Ell of Environment Takapuna opposed the wall. Erosion was happening along the coastline, she told commissioners, and landowners needed to accept that. She was concerned that the wall would encroach on public land for what, in her opinion, was for the applicants’ benefit only.

Auckland Council staff told the commissioners that erosion processes were natural and should be allowed to continue. They were unaware of any public complaints about the talus, safety or any request to remove the debris.

The commissioners’ decision of December 12 said the talus was now about 20m wide, runs about 10m from the toe of the cliff and is about 5m high.

The commissioners visited the site and said the man-made elements of the talus were unsightly and had adverse effects on amenity and natural and coastal character.

An image of a seawall, allowed to be built at the North Shore beach. Photo / Auckland Council

Ngāti Manuhiri attended an onsite meeting with the Peters and raised no significant cultural issues or effects. The iwi subsequently issued a kaitiaki report which assessed the seawall as resulting in adverse effects but noted that it is preferred over the existing talus materials.

Overall, Ngāti Manuhiri supported the application in principle, the commissioners’ report said.

“We find that while proposed seawall will be an obviously man-made structure, contrasting with the cliffs behind, that adverse effect will not be substantial or visually dominating,” the commissioners decided.

The wall would be a small element of the landscape and similar in scale to the existing debris, they decided.

“While the seawall may appear visually prominent when in close proximity, we find that it would not be visually dominating in the wider landscape,” they said.

The mature pōhutukawa would provide a visual containment and shading of the wall, reducing its visual prominence.

“Overall, the proposal is acceptable in terms of adverse effects on the environment and is generally consistent with the provisions of the relevant planning documents,” the commissioners said.

No mention was made of how much it would cost to build the wall.

The council lists 66 Seacliffe Ave as being valued for rating purposes at $11m and 68 Seacliffe Ave as being valued at $4.5m.