The toxic legacy of a mine

Toxic heavy metal contamination to waterways from the Tui Mine near Te Aroha by acid mine drainage has been measured at an alarming 5000kg each year, even thought the mine closed nearly 40 years ago.

In 2007, 5000 kg of heavy metals – zinc, iron, manganese and 100 kg of arsenic, cadmium, and lead was released from the Tui mine.  The Tui and Tunakohoia streams which flow into the Waihou River, and from there into the Firth of Thames, are totally devoid of fish and invertebrate life and are unsafe for humans.

This annual dose of contamination is likely to have been occurring at similar levels since the Tui mine closed in 1973.  Heavy metals are continuously released into the waterways from approximately 135,000 tonnes of mine waste (tailings) and two small mining tunnels.

“The alarming extent of the mining pollution is revealed in a March 2010 Assessment of Environmental Effects.  Plans are being prepared to clean up the Tui Mine contamination at a cost to taxpayers of approximately $17.5 million,” said Coromandel Watchdog spokesperson Denis Tegg.  “It is NZ’s most contaminated site.”

“When you compare Tui’s 135,000 tonnes of tailings to the current 40 million tonnes of tailings at Waihi’s Martha Mine, the potential threat to waterways is a very frightening scenario,” Mr. Tegg said.

“Newmont Waihi Gold’s Martha Mine has generated tailings approximately 300 times larger than those at the Tui mine. Using the Tui mine costings as a benchmark,  if just 10% of the Martha mine tailings required similar remedial work in the future the cost to taxpayers would be approximately $500 million,” said Mr. Tegg.

“Newmont has provided bonds of approximately $40 million.  But only a $10 million bond will be available in the long term, and even this is “reviewable”.  About 10 years after mine closure, Newmont will hand title of the tailings dam to a local Trust and the mining company will wipe its hands of any further liability.”

“If heavy metal pollution begins at Waihi any time in the next 100 years, taxpayers will be faced with an unprecedented environmental catastrophe, and huge clean up costs.   This is why the wild beauty of the Coromandel Peninsula should remain protected from mining, and why new tailings dams should never again be allowed” said Mr. Tegg.

“There are many examples of toxic pollution being caused by modern tailings dams in the USA and in other countries with high environmental standards.  The threat of the Martha tailings contaminating waterways is a very real one.”

1.    Assessment of Environmental Effects  – Tui Mine
2.    Tui Mine Remediation Cost estimates
3. Martha Mine Bonds


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