NZ - Coastal seawalls take on new urgency in Auckland, as properties crumble away
Consent applications for seawalls are taking on new urgency in Auckland, as coastal residents scramble to stop their homes from collapsing into the water.
Their mission has been brought into sharp focus in the wake of Cyclone Gabrielle, which saw hillsides and cliff-faces crumble across the city – forcefully bringing home the imminent risk faced by some multimillion-dollar properties.
Some wealthy owners are fighting back, and want to protect their properties with fortress-like rock seawalls that will hold back the forces of nature.
In Sunkist Bay in Beachlands, three households have applied to armour the shores with rock and mortar fortifications, in addition to the five already there.
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Conal Dempsey applied for a consent for his investment rental property on Hawke Crescent in August last year and has been waiting for a decision from independent commissioners.
While consultants and council planners argue the virtue ofmanaged retreat, the $1.75 million property continues to crumble away as a result of extreme weather events like Cyclone Gabrielle.
The tenant told Stuff that since last November the property had lost around half a metre of land, and the cliff was now less than two metres from the fence line.
“I woke up one morning and the sprinkler hoses were exposed out of the cliff. My big fear is that it’s getting undercut by the sea at the beach, and it could all collapse.”
Cliff failures in Auckland frequently make headlines. Most recently, a bach in Manukau Heads was taken out in a landslide, seriously injuring three holidaymakers inside it during the fall.
The problem is that waves and weather lash the brittle sandstone, causing it to crumble and retreat landward. The solution is described as “toe armouring”.
Seawalls are certainly not a new thing. Tamaki Drive has been bolstered by boulder walls for a hundred years. Auckland Council figures show that around 100 new seawalls have been consented over the last 10 years.
But perhaps what is new is the scale of these fortifications.
Dempsey’s plan is to build a 24-metre-long, two-tiered rock wall with 11 square metres of planting. The bulwark will reach five metres above the shore at its peak.
His own home a few doors down already has a winding path carved down the cliff leading to an extensive rock masonry rampart.
That’s not surprising. He owns half of Dempsey Wood, a major civil construction firm that claims to move 3 million cubic metres of earth each season, and pulls in contracts worth hundreds of millions of dollars.
But the age of climate-proof castles might be over before it really began. Council consultants seem positive about Dempsey’s proposal, but have warned it should be the last one.
“I strongly suggest that this site should remain as the last property to include such coastal protection intervention before retaining a more naturalised coastal edge,” landscape architect Peter Kensington wrote.
"I would not wish to see the entire coast of this localised bay having hard protection structures in place.”
