No workable solution to erosion

23:00, Mar 28 2014

The Environment Court has ruled there is no sustainable or practicable option to the erosion on Jackett Island.

Tasman ratepayers will now avoid paying millions of dollars cutting a channel through the Motueka sandspit.

The Tasman District Council's transportation manager, Gary Clark, said information gathered from the extensive coastal monitoring carried out as part of the process will now be used by the council to assess the impact of climate change and inundation on Motueka.

The council has spent $2.2 million in the four years since an island couple told councillors that a council-built groyne was locking up sand and was behind the erosion that was threatening their foreshore home.

Built in 1996 on the northern side of the Port Motueka to keep the channel clear the $1.4m groyne was blamed for storing sand and creating a huge sandbar which forced the port's channel to swing south, eroding the island foreshore and threatening Ben and Miranda Van Dyke's home.

In a 2012 hearing Judge Brian Dwyer roasted the council for "flagrant breaches" of its own permit conditions for the groyne and said in denying the problem existed, it forced the family to take legal action.


The council had to build and maintain a sandbag wall in front of the couple's home, come up with a sustainable solution to the erosion and pay the Van Dyke's $252,000 in costs.

The groyne was removed in 2012 after its consent expired.

Subsequent coastal modelling for a solution to the island's erosion by the council came up with a range of possible options with the preferred being a $7.5m navigable channel dredged through the encircling spit to reduce the velocity of water flowing past the island's foreshore.

Some sand would also have been regularly mechanically dumped on the island's beach.

However, the council went back to court last year and argued the option was unaffordable, it could not find a viable long-term solution, and that nature, not the groyne, was the cause of the erosion.

Mr Clark said the Environment Court made the decision based on the cost of the proposed preferred solution and the dynamic nature of the coastal environment.

"It is hard to justify spending that sort of money on protecting one property valued at less than $1m," he said.

The groyne had been a "little bit of a side issue" and had come through the initial court case as the cause. "But the reality is while the groyne's consent conditions had not been adhered to it was found not to be at fault.

"We have learned you have to be very careful when doing anything in such a dynamic coastal environment and we could have been more engaging with the Van Dykes.

"But ultimately if you decide consent conditions no long apply then you have to follow up with a formal process and document it."

Mr Clark said the council's coastal information would be available to any party that wished to apply for consent to work in that coastal environment. "But the council will not want to play in that sandpit."

The council would continue to maintain the sandbag wall in front of the Van Dyke's home and monitor the coastal environment for the next three years.

"The coastline is changing and very dynamic and the storms can be aggressive," he said.

Activity planning manager Sarah Downs said maintaining the sandbag wall for another three years would cost a further $200,000 to $300,000. Erosion to the island was continuing to shift south.

In her report to the council's engineering services meeting last month she said the council had sent a $144,044 cheque to the Van Dyke Family Trust to cover part of their $252,000 reimbursement claim.

"The remaining amount relates to future costs and it is considered inappropriate for the council to make this payment in light that there has been extensive logging works next to the Van Dyke property and the area concerned is very low lying and could be prone to inundation," she said.

The Van Dykes could not be reached for comment.

The Nelson Mail