Clean water by design—The impact of landform design on long-term water stewardship

Abstract

Mine Rock Stockpiles (MRSs) typically represent the majority of acidity generation potential at a mine site, a multigenerational water quality risk in respect of metal leaching and acid rock drainage (ML-ARD). Too frequently the extent of this risk is unrecognised and underfunded, resulting in a need for increased effluent collection and water treatment capacity after closure, and frequently, in perpetuity. Conventional water treatment options like lime treatment, result in a precipitated waste sludge, which then also requires a longterm disposal and remediation plan.Mine closure practitioners, when taking a long-term, full-lifecycle approach to design, appreciate that source term control is the highest level of hierarchical risk control in respect of source-pathway-receptor risk management. Applying source term control philosophy to MRS landform design presents an opportunity to reduce ML-ARD risk and the associated water treatment costs. Integration of passive, or semi-passive water treatment solutions into the mine affected landscape can further increase the value of this approach. This paper compares capital and operating costs using conventional mine rock placement methodologies paired with conventional effluent collection and treatment against an integrated mine closure landform and passive water treatment design. The value of the proposed integrated approach will be demonstrated not just through discussion of costs, but also the value of honouring and respecting water's sacred place in Indigenous knowledge systems.