Contaminated sawdust removal from beach car park to cost $6m

The Tāhunanui Back Beach car park will be dug up as part of a $6 million plan to remove contaminated sawdust that lies beneath.

The chemically-treated sawdust dates back to the 1960s when it was sourced from a local timber mill and used as fill for the raised car park but, over time, erosion has exposed the material.

Tests of the sawdust has found concentrations of arsenic, chromium, copper, and boron that could pose a risk to both the environment and human health.

Nelson City Council agreed to the remediation plan on Thursday.

Mayor Nick Smith said Tāhunanui Beach was “one of the most precious jewels” in Nelson’s crown and removing the sawdust was a "no-brainer".

"When I go down there… and I see hundreds of children, mokopuna playing on the beach, making their sandcastles, can I live with that thousands of tonnes of contaminated material being spread into that area where those kids are?” he asked.

"You have to do the right thing."

However, councillor Tim Skinner was concerned about opening a "Pandora’s box" by spending such a large amount on removing the material when there would be other areas around Nelson with similar amounts of toxic substances.

"We would be able to point the finger at a lot of places which may seem safe now, may not be safe soon, and it would just get out of control, so I think we have overreacted on this," he said.

Council staff highlighted that unlike other buried substances, the contaminated sawdust had been exposed by erosion at Tāhunanui Beach and was escaping into the environment.

Smith responded that it was important to follow the safety guidelines that had been scientifically developed but acknowledged the high cost.

"I am not prepared, as mayor of this city, to ignore that science," he said.

"I don’t think this council and the ratepayers can afford this without Government support."

The councilwas seeking funding Ministry for the Environment’s Contaminated Sites Remediation Fund that was hoped to cover most of the $5.8 million cost of the sawdust remediation project.

Work was not expected to begin until funding was confirmed.

The project would include removing 16,000 tonnes of material, including the sawdust and some sand that has also become contaminated, to landfill.

Once the material was removed, the site would be restored by establishing low-level dunes in place of the current car park with an alternative car park adjacent to the road.

Moving the carpark back to the road could protect it from coastal erosion for another 10-15 years, but would likely reduce 5-10 carparks due to the available space.

Councillor Pete Rainey moved an amendment to ensure the council would attempt to retain as many parks as possible.

"We know this is one of the preeminent sites for kitesurfing and [wing-]foiling in New Zealand, and I’m concerned that this is going to have dramatic effect on that activity."

Wiebke Bode, co-owner of the kitesurfing school Kitescool, acknowledged the council was in a "tricky" situation in protecting the carpark from erosion but would like to see as many parks retained as possible.

"The carparks are chocka in summer," she said.

"We do need to retain as many car parks as we can because it is such a cool area for water sporters but also for people walking their dogs, or just going for a walk, to access that part of the beach."

Local Democracy Reporting is local body journalism co-funded by RNZ and NZ On Air.