Policy guidance for identifying and effectively managing perpetual environmental impacts from new hardrock mines

Perpetual environmental management at operating and proposed hardrock mines is a rapidly expanding global dilemma. While economies of scale have encouraged larger mines, improved models routinely predict long-term water quality degradation at sulfide metal mines. Technical causes include oxidation of sulfide minerals and seepage from waste rock, tailings, and pit wall rock. Perpetual treatment is usually less expensive than permanent stabilization, even using 2% “risk-free” investment return rate; but this option greatly increases the social and financial complexity. A few regulations address perpetual management, but specific requirements range from formal acceptance to complete prohibition. With vague regulations, predictions of long-term impacts often delay permitting as operators and regulators grapple with model uncertainty and regulatory ambiguity. Risk management tools (e.g., insurance, inflation-protected investments, etc.) can reduce but cannot eliminate risk, and their continued availability is uncertain. What regulators and mine operators need – but do not have – is a clear framework to guide them in developing perpetual management plans that balance risks (e.g., uncertainty in predictions, cost, finance, and governance) and ensure responsible environmental and social stewardship. This paper responds with a review of perpetual mine management issues, including technical causes, policy examples, investment tools, case studies, technical remedies, and principles for successful long-term management.