Removal of failed groyne a costly affair

01:14, Jul 06 2012

Motueka's failed $1.4 million groyne is being dismantled, but questions still hang over its legacy of cost and erosion.

Work over the past two weeks has seen more than half the 700-metre length of ironsand-filled geotextile bags split and sucked clean by the sea, or suction hoses.

The emptied bags are being removed.

The groyne's removal is part of an Environment Court ruling won by Jackett Island landowners, the Van Dyke Family Trust, which successfully argued the groyne had locked up sand in a growing bar which diverted water from the Moutere Inlet channel across the island's foreshore, eroding tens of metres of beach.

Tasman District Council transportation manager Gary Clark said the groyne was being removed by contractors on a day rate to reduce the risk of cost overruns driven by the unknown variables of the depth of the groyne under the sand and sea.

The council has until the end of next month to complete the project.


"At this stage we are ahead of time and have only incurred half the expected cost," Mr Clark said.

Meanwhile, the council is in the process of calibrating a model of the effect of creating a channel cut through the sandspit on the current environment.

The results of this work would give staff an understanding of the effect of a dredged channel and other options the council should look at, he said.

But the cost is mounting.

The council spent about $830,000 last financial year, more than twice its $400,000 budget. The spend included building and maintaining a wall to protect the Van Dyke family home, modelling costs, resource consents and Environment Court costs.

It has budgeted $2.6 million for work this financial year.

Costs to come include removing the groyne, maintenance and monitoring of work protecting the island home, extra court costs of $252,197 and practical option investigations, reports and modelling.