Tui mine remediation project
On this page: about Tui Mine, remediation project, plans and reports, newsletters, newsletter subscriptions, open day resources
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:
- 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.
- 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.
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
- improve the visual appearance and aesthetics of the site, and
- to address as far as practicable, within the limitations of the project, the impacts of the Tui mine on the taonga of the Te Aroha maunga (Mt Te Aroha) for iwi.
The Waikato Regional Council 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 Waikato Regional Council, MfE, the landowners, Matamata Piako District Council (MPDC) and the Department of Conservation (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. A representative from the Iwi Advisory Group, comprising members of interested iwi including Ngati Rahiri Tumutumu, Te Kupenga O Ngati Hako and Ngati Haua, is also part of the project governance and steering group.
The project is being 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.
Phase 1 of the project is substantially completed within a budget of $5.5 million.
Phase 1 - Clearing Raise 3 ore chute
Phase 2 work started in October 2011 and is due to be fully completed in December 2013, within an estimated budget of $15.2 million.
A brochure is available that provides an overview of the project. You can download this brochure.
Plans and reports
Water quality monitoring report 2012-2013: adits 4 and 5 (Pattle Delamore Partners) (1 mb)
Monitoring report 2012 - Water quality monitoring after alkalinity injection (Pattle Delamore Partners) (3 mb)
Environmental monitoring plan - June 2011(Tonkin and Taylor) ( 1mb)
Summary of water quality testing 2012 (1mb)
You can receive email updates direct to your inbox by registering and subscribing to the Tui mine newsletter.
Domain Day - March 2012
An open day at Domain Day (at Te Aroha Domain) was held in March 2012, with opportunities to meet with the team, discuss progress of the Tui Mine remediation and view photographs of the works.
Resources for Domain Day
Baseline monitoring report 2010
Monitoring report 2011 - water quality monitoring (after alkalinity injection)
Summary of water quality testing results 2011 poster
Tui Pā open day (October 2011) resource material
Tui Mine remediation project brochure (6.51 MB)
Tui Mine open day posters (26 MB)
Tui Mine open day posters (second set) (1.46 MB)
Tui Mine open day banners (18 MB)