Mount Polley Tailings Dam Failure - More Lessons to Learn
Author: Ken J. Brouwer, Greg L. Smyth
Conference: CIM 2017 Convention
Date: April 30-May 3, 2017
ABSTRACT
The Mount Polley Tailings Facility was first constructed in 1996 at a time when three new mines were under development in BC, Canada (Mount Polley, Huckleberry and Kemess South). The design, review and regulatory oversight of these three projects were influenced by tailings facility failures that had occurred at that time (Merriespruit, South Africa (1994), Omai, Guyana (1995)). Qualified geotechnical engineers developed designs, Independent ngineering Reviews were conducted, and enforcement of mining regulations occurred with strong participation by the Provincial Government. The concurrent development of these mines allowed for lessons learned from one project to be applied to the others. For example, foundation instability in glaciolacustrine soils encountered during construction of the starter dam at the Kemess Tailings Facility resulted in review of similar glaciolacustrine soils at the Mount Polley Tailings Facility, and the early embankment designs incorporated suitably flat and/or buttressed slopes to accommodate the potentially weak foundation conditions. The Mount Polley dam failure occurred after the facility design was modified by incorporating steeper overall slopes for the higher embankments. Recent regulatory changes in BC mandate Independent Review Boards along with increased inspections by Regulators for tailings facilities. This will result in more conservative designs with increased oversight during all phases of mine operations, in order to foster a safer mining industry.
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