British Columbia Mine Reclamation Symposium

Mount Polley Mine August 2014 tailings dam embankment breach response and approach to remediation McMahen, Katie; Hughes, Colleen


On August 4, 2014, a foundation failure occurred at the Mount Polley Mine Tailings Storage Facility (TSF), releasing tailings, supernatant, and construction materials into the adjacent Polley Lake and down the Hazeltine Creek corridor into Quesnel Lake, causing erosion and deposition in the creek valley and deposition in Polley and Quesnel Lakes. Mount Polley Mining Corporation’s immediate response to the TSF embankment breach included: assessing and managing human health and safety risks; initiating a large-scale environmental monitoring program; and implementing interim sediment and erosion control measures in the Hazeltine Creek corridor. Subsequently, a control-oriented rehabilitation plan was initiated, which included reconstruction of the Hazeltine Creek channel. The next remediation phase, which is currently underway, involves installation of fish habitat features in Hazeltine and Edney Creeks, as well as rehabilitation of riparian and forest ecosystems in the floodplain and upland areas. This reclamation program is guided by results of the Human Health and Ecological Risk Assessment being conducted. A number of challenges were (and continue to be) met in the TSF embankment breach response process, primarily associated with: external communications; expedient implementation of environment monitoring, construction and rehabilitation programs; and challenging environmental conditions. It is anticipated that long-term monitoring of the receiving environment and rehabilitation works will be required, with continuous improvements being achieved through the adaptive management process that has been necessary to respond to challenges encountered thus far. Strong relationships among Mine representatives, regulators, First Nations and consultants continue to be a key component to moving forward with clarity, and are a precondition of long-term trust.

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