Contaminants cleared from mines
A $3.6 million clean-up of two of the most contaminated mine sites in New Zealand is complete.
Yesterday, Environment Minister Nick Smith and Conservation Minister Maggie Barry announced the Prohibition and Alexander mines on the West Coast had been ‘‘cleaned up’’ over the past 18 months.
‘‘The Prohibition and Alexander mine sites were acutely toxic and a blight on New Zealand’s clean, green reputation,’’ Smith said. ‘‘Their levels of arsenic were among the highest recorded anywhere in the world at 400,000 part 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 Department of Conservation (DOC) and the Ministry for the Environment’s Contaminated Sites Remediation Fund jointly funded the the two projects.
The Prohibition mine – at the historic gold mining town of Waiuta, about 37 kilometres south of Reefton – was the site of a roasting plant from 1935 to 1951, where arsenic bearing ore was roasted to release gold.
DOC inherited the site in 1987 and fenced it off to prevent possible harm and public access.
The Alexander processing plant, located east of Waiuta, produced the high levels of arsenic. It operated between 1934 and 1936 and closed in 1943.
‘‘These contaminated sites were the legacy of inadequate oversight and requirements of previous mining activities on the West Coast,’’ Smith said.
DOC released a statement in December saying 96 barrels of material highly-contaminated with arsenic were removed from the Prohibition site for treatment and disposal at a specialised facility.
Lesser contaminated materials were placed in a low-lying area on the site. The low-lying area was first lined with mullock, the waste rock from the mine excavations. The iron in the mullock binds with arsenic to remove the risk of contamination leaching into the ground, DOC said.
DOC’s western South Island director of operations Mark Davies said the remediation made the area safe for the public to visit.