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Posted on Thursday June 24th 2010 at 10:17 a.m.
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Wainui perfection, SOTD by Gavin
Written by Marianne Gillingham | Gisborne Herald
The council has applied to pull out the old railway iron and log wall alongside the Tuahine accessway, and replace it with a with a sloping rock barrier. It will start 10 metres out on the beach, rising to 3 metres above sea level at the bank, and continue all the way to the Wainui Stream.
Half a metre of the underlying papa rock will be excised to create a base for the rock revetment, with sand excavated from the area spread further along the beach.
They say the sloping rock wall will dissipate wave energy, protect the foredune, reduce erosion and possibly even trap sand.
The council says the effects on natural and amenity values of the area are likely to be minor.
Construction of such a wall requires a coastal permit because any disturbance of the environment within the coastal marine area is a restricted activity under the Resource Management Act.
The regional policy statement and district plan also include strong objectives to protect the environment from unsustainable land uses.
Some residents have taken strong exception to all or parts of the proposal, which has been extensively modified since it was first proposed.
Costs have been cited at between $15,000 and $26,000 per property.
An analysis of the submissions received showed that a number of property owners in the highest-risk area did not want such a scheme.
A hearing before independent commissioners Jim Dahm, John Matthew (chairman), Ross Muir and council representative Craig Bauld this week heard that only about half the people designated as direct beneficiaries - those who would have to fund the scheme - had indicated support.
More than 30 residents made submissions on the scheme, many of them verbal.
Amber Dunn, who recently completed a thesis on erosion at Wainui Beach, says the wall will offer only partial protection from erosion and is not consistent with the design advocated in a peer review. She says it also overlooks the need for access to the beach over the rock wall.
Some of the data relating to sand levels and erosion patterns used to justify the work was questionable, she says.
Dr Robin Briant said the plan was based on saving private property, not on enhancing or even maintaining the beach.
The scheme, like its forerunners, had a high potential for failure. The revetment wall could redirect wave pressure to the north and south, accelerating erosion on other parts of the beach.
Another report had already warned the rock revetment could increase the downward pressure on the fronting mudstone.
The concept contradicted numerous clauses in the New Zealand Coastal Policy Statement, including requirements to promote alternatives to protection structures, take into account the effects of climate change over a century and assess cost benefits in line with this. The need to maintain public access was also a key aspect of this policy.
Laurie Lautman said the original design had been modified to an extent where it should again be subjected to a peer review. If the revetment worked in protecting property, the ocean would simply take what was in front of it.
Short-term property protection would be unsustainable long term. The council might as well drop money over the bank.
Some submitters feared the wall would lead to a similar scenario as Tatapouri, where structures protecting the road had led the once sandy beach to become a denuded papa shelf.
Richard Suttor said he had lived in Murphy Road since 1957. There had been a small amount of erosion at the southern end of the beach when the groynes were put in. These made it worse and were removed.
Since the log and rail wall had been built in 1960, there had been no net erosion at all over time. Sand levels went up and down, but always came back.
The Murphy Road frontage was eroded in 1992-93 when there was a series of southerly storms. It has since come back and was now a grassy bank. Essentially there had been no change over time.
Read more at the Gisborne Herald
Written by Marianne Gillingham
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