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Two-phase clean up

Two-phase clean up

The first phase is to prepare the site and remediate the underground parts of the mine. The $4.5 million cost of this is funded by the Ministry for the Environment’s Contaminated Sites Remediation Fund.

Phase 1

Preparing the site and remediation of the underground parts of the mine:

  • installation of a concrete bulkhead at the lowest discharge point from the mine

  • injections of limestone slurry into the mine workings to reduce the potential for acid rock drainage

  • re-contouring and stabilisation of waste rock stockpiles dumped in the Tunakohoia Stream when the mine was operating; this will significantly reduce the contaminant loads that are currently being discharged into the environment.

Proposed action plan (subject to consent)

Mid 2010

  • Upgrade of Tui Rd, Mount Te Aroha access road and access tracks at the site.

  • Some of these upgrade works were completed during the remediation trials late in 2009, while the extension of the surfacing of the Tui Rd was completed late February 2010.

  • Lime injections into the mine workings will continue with regular repeats for about the next two years, and then periodically as required.
  • This process was tested and confirmed to be sucessful as part of the remediation trials in October 2009.

  • Works within the underground workings, involving the installation of safety features within the Champion level 4 and 5 adit entrances, coffer dams, limestone bunds and outlet control works, and installing the Champion level 5 bulkhead. This is expected to take about eight months.

Summer 2010/11

  • Work to remediate the waste rock piles at level 4 and 5 adits (entrances to the mine) will take about two months.

2011 onward

  • General maintenance and monitoring of the site will be ongoing from 2011.

Phase 2

The Ministry for the Environment is seeking the estimated $13 million funding for the second phase which involves remediating the tailings dam area and making the former ore processing area safe for public access. The second phase includes: 

  • stabilising the tailings dam using a combination of in-situ stabilisation and blending of tailings, waste rock and lime/cement to provide a geotechnically stable landform with significantly less acid rock drainage potential
  • making safe the former ore processing area and tailings dam for general public access and further improving the site through plantings and recreational/educational opportunities.

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