The sand was shipped into the city from Golden Bay in 2004 to enlarge the beaches of Oriental Bay.
Like sands through the hour glass, so are the bills to ratepayers.
Shifting 22 tonnes of sand at Oriental Bay costs Wellington ratepayers nearly $70,000 every year.
On Tuesday the Wellington City Council completed its last bi-annual beach survey, measuring the sand shift at the artificial beach.
The sand was shipped into the city from Golden Bay in 2004 to enlarge the beaches of Oriental Bay, costing $7.5 million.
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Council marine and coastal project manager Peter Hemsley said because it was an artificial beach, the council needed to keep “close tabs” on how much sand moved.
“We have a comprehensive programme in place to manage this.”
Beach monitoring and consent compliance cost $26,500 each year.
Sand was surveyed twice a year at a total cost of $12,000, and then shifted twice a year at $30,000 total.
That brought the total annual cost of maintaining Oriental Bay’s beaches to $68,500 a year.
In 2015 new sand was shipped in from a quarry in Dunedin at a cost of $400,000.
Cuttriss Consultants undertook topographical field surveys of the sand and Tonkin and Taylor managed the monitoring and maintenance.
Without monitoring and shifting the sand would accumulate at the western end of the beach and spill out into the harbour where it would be lost.
Surveyors plot the elevations of the sand to build a 3D model of the beach.
Surveyor Rachel Charlesworth said the topographical sand measurements are not just undertaken on the sandy beach.
“Our surveyor, Jeff Macphail, has to swim out quite far towards the fountain to get measurements, positioning a pole along section lines.”
Tonkin and Taylor civil engineer James Moore said the orientation of the beach meant waves caused longshore sand drift from east to west.
“As the beaches are artificial, there is no sand further around the coast to naturally replenish the eastern end of the beach.”
In 2004, the council shipped in 22,000 tonnes of sand from the Golden Bay area – not the beach itself – to enlarge the beach areas of Oriental Bay.
Around the same time, the Freyberg Beach grass area was developed and a new playground built.
The project won numerous awards including NZ Institute of Landscape and Architects Supreme Award and an Innovate NZ Gold Award.