Tailings, Waste Rock and Water Management

Okane’s Services:

  • Waste Rock Characterization and Management Plans
  • Waste Rock Storage Facility Internal Conditions
  • Climate and Water Balance Modeling
  • Surface Water Management
  • Tailings Characterization and Management Plans
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Mine Waste Management

Mining activities produce various types of mine waste such as tailings and mined rock. Tailings are the uneconomic materials left over after separation from the ore, while mined rock is permanently stored at the mine site and never processed. Both tailings and mined rock can potentially release acid and metalliferous drainage/acid rock drainage and need to be managed to mitigate negative effects to the surrounding area. At Okane, we have 25 years experience in mine waste management. We take an integrated approach to mine waste management by incorporating strategies for both tailings and mined rock throughout the entire mine lifecycle.

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Tailings Management

Okane takes a comprehensive near-term and future-vision approach to tailing storage facility closure design and management. Through specialized instrumentation, modelling capabilities and expert knowledge of the unsaturated zone, we develop a comprehensive understanding of tailing storage facility dewatering mechanisms and behaviour. Our geochemical experts investigate water quality associated with tailings seepage to assist clients achieve regulatory obligations. Okane’s integrated approach to waste management is demonstrated through our experience managing transitions from filtration ponds to dry stack tailing storage facilities, and through the design of co-disposal (filtered tailings and waste rock) facilities.

Waste Rock Stockpile Design

One of the most persistent challenges for mine operators is poor post-closure water quality related to acid rock drainage or acid and metalliferous drainage (ARD/AMD) Often referred to as waste rock dumps, mine rock stockpiles are frequently the majority contributor to acidity load. As authors of the International Network for Acid Prevention Rock Placement Strategies to Enhance Operational and Closure Performance of Mine Rock Stockpiles guidance document, Okane’s team are experts in the field of unsaturated zone hydrology, and the numerical modelling of acidity generation and suboxic conditions in mine rock stockpiles.

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Fundamentally, limiting ARD/ AMD from a mine rock stockpile is about managing the supply of oxygen into reactive waste and limiting contaminant transport through surface water management. We combine geochemical and hydrological modelling to evaluate mined rock stockpile designs and provide recommendations of construction methods to reduce ARD/AMD. By considering additional performance metrics such as projected seepage water quality and landform evolution during mine rock stockpile design and construction, we can better understand the potential impacts of post closure liability on net present value (NPV). Our designs integrate mine plan volumes, schedules, and geology for strategic placement of mine waste during operations to manage ARD/AMD risk so that reliance on a final cover system is not the only mitigation. We work with our clients to incorporate improved mine rock stockpile designs and construction methods directly into mine plans to increase efficiency and reduce long term water treatment costs and post-closure water quality liability.

Surface Water Management

Okane has extensive experience designing site-specific water management plans for waste storage facilities and developing overall site-wide water balances. Our designs incorporate the potential effects of climate change into water balance models throughout the mine lifecycle. Our advanced models integrate detailed drain down design with the overall landform and site-specific hydrology and hydrogeology. We leverage site assets like pit lakes or saturated rock fills to blend engineered reclamation structures and passive water treatment solutions into the surrounding environment, increasing aesthetic appeal, stakeholder approval, and minimizing the requirement for onsite treatment and maintenance.

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