Mine Environment Life-cycle Guide: epithermal gold mines Authors JE Cavanagh1, J Pope2, R Simcock1, JS Harding3, D Trumm2, D Craw4, P Weber5, J Webster-Brown6, F Eppink1 , K Simon7 1 Manaaki Whenua – Landcare Research 2 CRL Energy 3 School of Biological Sciences, University of Canterbury 4 School of Geological Sciences, University of Otago 5 O’Kane Consulting 6 Waterways Centre 7 School of Environment, University of Auckland © Landcare Research New Zealand Ltd and CRL Energy Ltd 2018 This information may be copied or reproduced electronically and distributed to others without limitation, provided Landcare Research New Zealand Limited and CRL Energy Limited are acknowledged as the source of information. Under no circumstances may a charge be made for this information without the express permission of Landcare Research New Zealand Limited and CRL Energy Limited. ACKNOWLEDGEMENTS The Mine Environment Life-cycle Guide series extends the New Zealand Minerals Sector Environmental Framework previously developed by Landcare Research (as Contract Report LC2033), CRL Energy, and the Universities of Canterbury and Otago, in conjunction with end-users including the Department of Conservation, the West Coast Regional Council, Environment Southland, Solid Energy, OceanaGold, Francis Mining, Bathurst Resources, Newmont, Waikato Regional Council, and the Tui Mine Iwi Advisory Group. Contributors to the previous framework also included Craig Ross. The Mine Environment Life-cycle Guide has been developed with input from end-users including the Department of Conservation, Straterra, West Coast Regional Council, Waikato Regional Council, Northland Regional Council, New Zealand Coal and Carbon, OceanaGold, Bathurst Resources, Solid Energy New Zealand, Tui Mine Iwi Advisory Group – in particular Pauline Clarkin, Ngātiwai Trust Board, Ngāi Tahu, and Minerals West Coast. Thanks also to Malcolm Lane from Lane and Associates for advice on mine bonding arrangements. Funding was provided by the Science and Innovation Group, Ministry of Business, Innovation and Employment. EXECUTIVE SUMMARY Mining is an important economic activity in New Zealand, and it has a long history that is often linked with important cultural developments. The process of mineral extraction inevitably affects the surrounding environment, but there are few tools available to help mining companies and regulators assess and predict the environmental impacts of mining operations for New Zealand’s geology and environmental conditions. The Mine Environmental Life-cycle Guides (MELGs) follow on from the New Zealand Minerals Sector Environmental Framework and the Mine Drainage Framework and have been developed as part of a collaborative research programme with key mining partners to assist with the planning of future mine developments in New Zealand. A separate MELG has been developed for different generic mine types: mesothermal gold, epithermal gold, and potentially acid-forming and non-acid-forming coal. The MELGs bring together previous minerals sector environmental planning tools and provide guidance for minerals sector companies as they proceed through operations to closure and post-closure. They include guidance on stakeholder engagement (particularly iwi engagement) and seek to reduce the uncertainty surrounding the achievement of agreed post-mining outcomes for future, operating, and closed mines during planning, operations, and closure. The MELGs result from a collaborative research programme between CRL Energy Ltd, University of Canterbury, University of Otago, University of Auckland, O’Kane Consultants (NZ) Ltd and Manaaki Whenua – Landcare Research, and they have been developed in conjunction with end-users including the Department of Conservation, Straterra, West Coast Regional Council, Waikato Regional Council, Northland Regional Council, New Zealand Coal and Carbon, OceanaGold, Bathurst Resources, Solid Energy New Zealand, Tui Mine Iwi Advisory Group, Ngātiwai Trust Board, Ngāi Tahu, and Minerals West Coast. Specifically, the MELGs examine the geochemistry of mine waste rock and mine drainage, the freshwater ecology of mine- affected catchments, and the effectiveness of water treatment techniques and terrestrial rehabilitation techniques for different mine types and environments to achieve intended outcomes. The guides highlight innovations within the minerals sector in New Zealand using case studies, and incorporate current knowledge from the global minerals sector to provide guidance on state-of-the-art mine environment management practices. In addition, the economics of alternative environmental management options are assessed. Increasingly, a social licence to operate is required to enable successful minerals sector development, which requires meaningful participation from iwi, local communities, and other stakeholder groups. Changes to mining legislation and regulatory guidance also place increased focus on iwi participation and engagement. For this reason, stakeholder engagement – particularly iwi engagement – from an early stage of mine planning is a focus in the MELGs. In New Zealand, ‘everywhere is someone’s back yard’ compared to other countries, where mining often occurs in unpopulated or sparsely populated areas. Further, for iwi, rohe and areas of interest can be complex and overlapping. Although no generic approach to participation and engagement will be appropriate for all sites, there are some common themes that have been articulated by Māori, mining companies and regulators, and these are incorporated in the MELGs. The MELGs are written for a wide audience (e.g. regulators, mining companies, landholders, and the community) and should assist with regulatory processes, such as access arrangements with the Department of Conservation, assessments of environmental effects (AEEs) for resource consenting, and the development of resource consent conditions. The document should also help internal decision-making by mining companies and in Resource Management Act processes. CONTENTS Acknowledgements ...................................................................................................................... 3 Executive summary ...................................................................................................................... 4 Abbreviations ............................................................................................................................ 12 Glossary ..................................................................................................................................... 13 1 Introduction ..................................................................................................................... 17 Epithermal gold ........................................................................................................................................................... 17 1.1.1 Summary of activity ........................................................................................................................................ 17 1.1.2 Geology ........................................................................................................................................................... 18 Regulatory requirements ............................................................................................................................................ 19 1.2.1 Mining permit ................................................................................................................................................. 20 1.2.2 Land access arrangements .............................................................................................................................. 21 1.2.3 Resource consents .......................................................................................................................................... 22 1.2.4 Other statutory instruments to be considered ............................................................................................... 23 Decision-making .......................................................................................................................................................... 25 1.3.1 Potential environmental effects of mining ..................................................................................................... 26 1.3.2 Cultural impacts .............................................................................................................................................. 33 1.3.3 Economic impacts ........................................................................................................................................... 34 1.3.4 Iwi engagement .............................................................................................................................................. 35 1.3.5 Stakeholder engagement ................................................................................................................................ 36 The Mine Environment Life-cycle Guide ...................................................................................................................... 37 2 Exploration ....................................................................................................................... 41 Prospecting ................................................................................................................................................................. 41 Exploration .................................................................................................................................................................