1. Introduction
Mining is an important part of the New Zealand economy, valued at $1.5 billion per annum (Crown Minerals 2007), and predictions are that this could reach $2.0 billion by 2010 and $3.0 billion by 2015 (Statistics New Zealand 2007). New Zealand has a long history of mining, with European settlers extracting coal and gold since the 1860s. Most residential, commercial and industrial products use minerals during their production and thus mining will remain an important industry into the future. However, the removal of minerals from the ground inevitably results in significant negative impacts on the environment. Increasingly, miners are being required to reduce and minimise these impacts.
The West Coast of the South Island and Southland are key mining areas, with potential for increased mining activity.
This document describes a framework to assist with planning of future mine developments on the West Coast and in Southland. The framework results from a collaborative research programme between CRL Energy, the University of Canterbury, University of Otago and Landcare Research, and it has been developed in conjunction with end-users including the Department of Conservation, the West Coast Regional Council, Environment Southland, Solid Energy, OceanaGold, Pike River Coal, Francis Mining and consultants. It is intended to provide consistency and transparency in decision making for proposed mining operations, specifically around preventing or minimising impacts on streams. The framework is intended for use in internal decision-making by mining companies and to assist with certain regulatory requirements, such as access arrangements with the Department of Conservation, and in the resource consenting process, such as during consultation, assessment of environmental effects (AEE), and setting resource consent conditions. The framework may also be useful in developing future regional plans for water quality.
This framework focuses on water quality issues associated with coal and gold mining, specifically pH, metals and turbidity, and does not address other water quality measures such as temperature, or environmental issues that also may need to be considered during mine planning and consenting such as stream diversions, water quantity, noise, traffic, visual, dust, and subsidence issues.
Commencing with a general introduction to mining on the West Coast and Southland and water quality impacts associated with mining, this document outlines a process for determining environmental impacts on aquatic systems. The framework draws together research undertaken by the research team on rock geochemistry, aquatic chemistry, freshwater ecology, aquatic toxicity, and management and treatment techniques for mining, and provides guidance on:
Interpretation of regional trends in rock geochemistry and prediction of mine drainage chemistry;
Sampling strategies and analysis methods for mine drainage prediction and management;
Effects-based ecological impact thresholds;
Sampling strategies and methods for water quality and biological impact assessment and monitoring;Management strategies for waste rock and mine tailings; andOptimal selection of active and passive treatment systems.
