Archived content: This media release was accurate on the date of publication. 


Work to clean up the most highly arsenic contaminated site recorded in New Zealand, at Waiuta on the West Coast of the South Island is now complete and the site has been reopened to the public.

Date:  16 December 2016

Contamination at the historic Prohibition mine processing plant at Waiuta was the result of a process used to extract gold from arsenic bearing rock. The processing plant operated from 1938 till 1951, when the mine closed and was abandoned following the collapse of the main shaft.

In the cleanup, which was carried out between August and November, 96 barrels of highly arsenic contaminated material were removed from the 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 any contamination leaching into the ground. Mullock was placed on top of the material and compacted to create a solid surface and make sure people cannot be exposed to any contamination.

Testing of water leaving the site shows that the remediation has been successful.

Mark Davies, Western South Island Director Operations says that the remediation has made the area safe for the public to visit, and has stopped arsenic leaching into the wider environment.

"This area has a fascinating social and industrial history that we want visitors to experience, and the remediation is key to that. The site is now ready for us to develop a mining history experience that will complement our existing network of attractions such as Denniston and the Brunner Mine Site".

The $2.6 million remediation was jointly funded by DOC and the Ministry for the Environment's Contaminated Sites Remediation Fund.


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