1. New Zealand Minerals Sector Environmental Impacts and Mine Drainage Framework James Pope

2. Contents 1. 1. Introduction - where are our minerals? 2. 2. What are the main impacts of mining and how variable are they? 3. 3. Are mine impacts predictable? 4. 4. Mine drainage decision support framework 5. 5. Summary

3. 1 Where are our mineral resources? Gold mines Coromandel West Coast SI Otago Coal mines Waikato West Coast SI Southland Gold potential Northland Taupo VZ Nelson South Westland Coal potential Taranaki Otago Platinum potential Nelson Southland

4. 2 Impacts and their variability   Onsite (or close)   Landscape change   Disturbance to flora and fauna   Rock geochemistry   Groundwater   Noise   Dust   Vibration   Offsite   Mine drainage

5. Rock Geochemistry and Mine Drainages  Mine impact on drainages occurs through exposure of waste rock to atmospheric weathering conditions – Text book case is Acid Mine Drainage – but mine drainages are variable  Mitigation is through active treatment is common at operating mines – Historic mines abandoned rather than closed  Critical geochemical questions when planning or operating a mine: 1. What mine drainage chemistry will occur? 2. What will change with time?  Related issues – How does mine drainage chemistry differ from local background? – What is the impact of mine discharge? – Is it acceptable? – How can it be treated if necessary? – How can it be minimised, managed and prevented?

6. Historic coal mines   Landscape – Rock Geochemistry – Mine Drainage

7. Historic gold ore processing Dave Craw Laura Haffert   Landscape – Rock Geochemistry – Mine Drainage

8. Current coal mine   Landscape – Rock Geochemistry – Mine Drainage

9. Current gold mine   Landscape – Rock Geochemistry – Mine Drainage

10. How variable are the impacts? Morley CM Gore Lignite Measures   Drainages from historic and current mines

11. 4 Are the impacts predictable? Quantify variability and identify underpinning science Accurate prediction of impact Proactive management plan Appropriate mitigation, rehabilitation, offset and/or bonding Informed resource use decision

12. Predicting NZ coal mine drainage geochemistry  Rock geochemistry from drill core Brunner Coal Measures Acid base accounting analyses

13. Predicting NZ coal mine drainage geochemistry  Kinetic testing

14. Predicting NZ coal mine drainage geochemistry  Kinetic testing

15. Predicting NZ epithermal gold mine drainage  Kinetic tests indicate lag periods before acid formation  Trace elements include Cu, Pb, Ni, Zn, Mn, Hg

16. Predicting NZ meso-thermal gold mine drainage  As enriched neutral mine drainages   Dave Craw & Laura Haffert

17. Predicting impact on aquatic ecosystems  Food web response to mine drainage related   Jon Harding

18. Using our predictions – what is optimal treatment or management  Builds on predictions of mine drainage chemistry  International recognition of our developments and innovations  Passive mine drainage treatment and As, Sb, Mn removal all cutting edge Dave Trumm, Paul Weber and Rachel Rait

19. 5 Mine Drainage Framework  Framework document  Many peer reviewed and conference publications

20. Framework  …integrates current multidisciplinary science – Geochemistry – Aquatic biology – Treatment/management  …predicts mine drainage chemistry and ecological impact  …provides a decision support system for the mining industry and regulators  …provides general environmental management information on issues that are site specific  …is a multi-level document that includes generic and qualitative guidelines to raw data and scientific papers

21. The Framework does not…  … provide a prescriptive geochemical or biological testing and analysis regime - guidelines only  … provide a prescriptive recipe for resource management or rehabilitation – guidelines only  … determine ‘acceptable’ vs ‘unaccepable’ ecological impact levels  … determine ‘acceptable’ vs ‘unaccepable’ resource development

22. 6 Summary  NZ has substantial and widely distributed mineral resources  NZ has legacy mine drainage issues  Minerals sector impacts are diverse  Rock geochemistry and mine drainage chemistry is highly variable but predictable  Broad prediction of impacts on aquatic ecosystems can be made  Management options are available  Framework for mine drainage issues  Acceptable impact or not ….

23. Acknowledgements  Organisers  MBIE  Oceana Gold, Francis Group, Solid Energy – Newmont, Buller Coal  DoC, WCRC, Environment Southland – Waikato Regional Council, Straterra