Metalliferous mine closure geochemical risk planning and validation template

Abstract

Mining companies have many legal obligations, business requirements and stakeholder expectations, with regards to mine site closure. Decisions and activities at any stage in the operation can have environmental, reputational and financial consequences into the long term, especially when considering the management of geochemical risk posed by mine waste. Few would disagree that every closure is site specific, but the authors suggest that use of existing global and regional guidelines available for closure have the potential to result in significant gaps in a site’s closure plan. This is due to the generalised nature of existing guidance, the site specific nature of geochemical risks, key differences between metalliferous and non metalliferous mines, and a focus in recent guidance on geotechnical risks and social governance. A site-specific framework for metalliferous mines with a focus on closure geochemical risk that draws on the best examples of the existing guidelines and industry best practice is proposed as an opportunity to reduce these risks. The intent of the framework, is that risk can be assessed using a templated type assessment which, when populated, would be assessed through an independent validation process that would allow for companies to benchmark their sites with respect to geochemical risk management. Existing guidelines from government and industry organisations are examined together with a review of examples of corporate closure governance. Guidelines are reviewed from Europe, Western Australia, Queensland, International Council of Mining and Metals (ICMM), International Standard of Organisation (ISO) and the Global Acid Rock Drainage (GARD) Guide. In addition, several mining company closure standards are examined. By examining the current industry and legislative guidelines, and by drawing on site specific case studies, this paper will address the potential weaknesses within the generalised guidelines, particularly with regards to geochemical risk assessment, with the aim of developing a site-specific closure framework that could be part of a corporate closure governance framework. The framework has drawn on the integrated approach where requirements, by life of mine cycle, are detailed. The listing of the requirements allows for companies to ensure the approach that is adopted reflects their company policy, values and commitments, conditions required by membership of industry associations or corporate accreditations etc. As such the resulting template offers site a sound framework from which to identify a comprehensive list of geochemical related closure activities to enhance the closure planning process, which can reflect both the company values, local judication and stakeholder expectations.