Abandoned mine cleanup cost put at $17.4m

TUI'S EYE VIEW: An aerial photo shows the Tui mine, on Mt Te Aroha above the town.
TUI'S EYE VIEW: An aerial photo shows the Tui mine, on Mt Te Aroha above the town.

Cleaning up the abandoned Tui mine in Waikato will cost taxpayers $17.4 million – almost double the initial budget – amid fears cyanide is buried at the site.

The project's leader says the risk of the mine's dam giving way and Te Aroha township being flooded with dangerous waste have increased.

The Tui mine at Mt Te Aroha was abandoned in 1973 when the market for its ore dried up because of its high mercury content.

Heavy metals are leaching from the tailings dam into the Tui and Tunakohoia streams, and the dam could collapse – leaving an estimated 100,000 cubic metres of contaminated waste threatening Te Aroha.

Tailings is residue left by the mining process.

Tui mine project manager Ghassan Basheer said a former mine worker had told Environment Waikato that cyanide drums had been buried beneath the tailings dam.

Drilling had not found any, but Mr Basheer said they would have dissolved in the highly acidic environment by now. Traces of cyanide had been discovered.

"This is dangerous. It can kill people. Our approach is to be cautious. We can't underestimate the risks here."

Pat Elley who lives in the house closest to the mine said: "We are the first in the firing line."

Though she was worried about the possibility of the dam collapsing, she had a "false sense of security" as it had survived a strong storm in 1985.

Heavy metals leaching into the now-dead streams were most concerning for their environmental impact, but Mrs Elley said the cyanide drums were a new concern.

Peter Jackson, 73, worked at the mine from 1962 till 1973 and said he believed the cleanup was a waste of money.

"I don't think it will ever collapse. Look at all the storms it has survived."

However, Mr Basheer said the dam was not well engineered and an earthquake or flash flooding presented a real risk of collapse. He said it was up to the Government to decide whether funding the work was a priority. "Knowing what's sitting in there, we believe it is a high-risk area. Something has to be done. The sooner the better."

Environment Minister Nick Smith said he had asked for a report on the stability of the dam before committing extra funding.

The Environment Ministry administered a "contaminated sites remediation fund" which helped councils investigate, plan, and fix contaminated sites. That fund was already "committed" to projects in the coming years, including contributing to the Waiwhetu Stream cleanup in Lower Hutt. "The budget in this area is under some pressure."

Dr Smith said he had signalled to Environment Waikato and Matamata Piako District Council that they would need to contribute to the cost of the Tui mine cleanup.

"It's unrealistic that the taxpayer will foot the full bill of the orphan contaminated sites."

Last month, the Government announced it was proposing opening up more than 7000 hectares of conservation land to mining.

Chris Baker, spokesman of Straterra which represents the natural resources industry, said the Resource Management Act meant a more stringent framework existed now than when the Tui mine was active.

The Dominion Post