Tui mine
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About Tui mine
The Tui mine site consists of underground mine workings (“adits”), waste rock dumps and ore stockpiles, and deposited tailings from the ore processing. There are a number of water discharges from the site including drainage from adits, contaminated under drainage from waste rock and tailings, and natural sources.
There are three main issues arising as a result of the mining activity at this site. These are:
- the Tunakohoia stream, located on Crown land managed by the Department of Conservation (DOC), is affected by heavy metals leaching from the adits and from the tailings dam. These heavy metals, including lead and cadmium, are contaminating the Tunakohoia stream which flows through the centre of the Te Aroha township;
- the Tui catchment is adjacent to but separate from the Tunakohoia catchment. The Tui catchment is also affected by heavy metals arising from the tailings dam; and
- there is an abandoned mine tailing impoundment in the Tui catchment, on land owned by the Matamata-Piako District Council (MPDC). Technical reports have found that this structure is at risk of collapse in a moderate seismic event or an extreme weather event. Such events could result in over 90,000 m3 of mine waste liquefying and flowing down the Tui stream past the edge of Te Aroha.
Remediation project
The Tui Mine remediation project aims to:
- contain the tailings within a stable and secure location;
- reduce the release of contaminants into the Tui and Tunakohoia streams, thereby improving the water quality in those streams;
- improve the geotechnical stability of the tailings impoundment;
- improve the safety and security of the site; and
- improve the visual appearance and aesthetics of the site.
Environment Waikato (EW) has been involved in the management of the Tui Mine remediation works since June 2007, when the Ministry for the Environment (MfE) announced funding for the project. The project is overseen by a governance group comprising the Senior Management of MfE, EW, and the landowners, MPDC, DOC. Local iwi Ngāti Rāhiri Tumutumu are also to be part of project governance. A steering group including senior staff from the main parties will oversee the project’s implementation.
The project will be completed in two phases:
- Phase 1 involves preparatory work (detailed design, site establishment, access road) and the treatment of the old underground mine workings. The old mine workings discharge contaminated water into the Tunakohoia Stream. The plan is to partially plug these workings with engineered concrete bulkheads, and to inject an alkaline solution (lime or cement) into the ground to counter the strongly acidic conditions.
- Phase 2 involves remediating the tailings dam area. The initial plan was to contain the tailings in a new dam built to modern standards. It is now proposed to change the nature of the tailings so they become dry enough to play into a secure mound on the site. The mound will be properly drained and capped, and lime or cement added to prevent acid build-up.
Depending on the outcome of the final trials and the granting of necessary consents, it is expected work on the underground mine workings will start in February 2010. The aim is to complete the underground workings remediation in June 2010 and, subject to funding and consents, the tailings remediation by June 2011.
Open day resource material
A successful open day was held on Thursday, 26 November, 2009. The presentation, booklet and posters are available for you to download and view below in pdf format.
Tui Mine Resource Consent Open Day - presentation
(6980 kb, 997 seconds to download, 56k modem)
Tui Mine post-remediation options design study - booklet
(4164 kb, 594 seconds to download, 56k modem)
Tui Mine - posters
(1696 kb, 242 seconds to download, 56k modem)
Your feedback
Feedback on the Tui Mine remediation project was closed on Friday 18 December 2009. Stay posted for more information.
Newsletters
The November 2009 newsletter - Tui Mine Cleanup is now available on this website.
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