Contaminated West Coast mines remediated

  • Maggie Barry
  • Nick Smith
Environment Conservation

The top two most contaminated sites in New Zealand have been successfully remediated, Environment Minister Dr Nick Smith and Conservation Minister Maggie Barry said today.

“The Prohibition and Alexander mines on the West Coast topped a list of the most contaminated sites in New Zealand,” Dr Smith says.

“They have been cleaned up during the past 18 months in projects jointly funded by the Department of Conservation (DOC) and the Ministry for the Environment’s Contaminated Sites Remediation Fund. The two projects cost $3.6 million to complete.

“The Prohibition and Alexander mine sites were acutely toxic and a blight on New Zealand’s clean, green reputation. Their levels of arsenic were among the highest recorded anywhere in the world at 400,000 parts per million on land, or 500 times the safe level, and in water at 300 parts per million, or 33,000 times the safe limit for drinking water.

“The Prohibition mine site was contaminated from the operation of a roasting plant from 1935 to 1951, when arsenic bearing ore was roasted to release gold. The sites also have high levels of mercury and cyanide. The mining company has long gone and DOC inherited the site in 1987,” Ms Barry says.

“The Alexander processing plant that produced the high levels of arsenic operated between 1934 and 1936. The mine closed in 1943.

“These contaminated sites were the legacy of inadequate oversight and requirements of previous mining activities on the West Coast. We need to repair the environmental damage and clean up this site, but also ensure that we properly regulate mining activities today so as not to create more problems of this sort in the future,” Dr Smith concluded.