INAP's Global Cover System Design Technical Guidance Document


Mike O'Kane (O'Kane Consultants Inc.)

The International Network for Acid Prevention (INAP) is an organization of international mining companies dedicated to reducing liabilities associated with sulphide mine materials. The liabilities associated with mine closure span the globe, occurring across broad spectrum of climate, hydrogeological and material settings. Cover systems are a practical tool in managing closure liability surrounding reactive wastes, and thus are required to perform under a broad range of site specific conditions. Previous guidance has specifically addressed cover system design as it pertains to cold regions but to date, no further information exists as it specifically pertains to cover system design on a global scale. This paper describes the technical guidance approach for cover systems globally that is being developed by INAP with the assistance of a Technical Advisory Group (TAG). The focus of the paper is a conceptual filter framework philosophy used to rapidly refine cover system alternatives through a set of site specific filters, to more efficiently determine cover systems for further evaluation. Site specific filters employ the Köppen−Geiger climate classification system to incorporate seasonality into design. A process based approach is used through each refinement to better understand mechanisms and controls that can be exploited, enhanced and combined to achieve reductions in acidity generation and transport. The management of oxygen and net percolation based on each site specific filter is discussed in detail along with timing of reclamation and performance value. Evaluation of cover system performance and risk is not possible or complete without discussion of performance assessment period and design life. The document’s second focus surrounds generic case studies and real case studies to further demonstrate the utility of the proposed framework.
Keywords: Mine Waste Management, Cover Systems, Acid Rock Drainage, INAP