So you Need to build a Waste Rock Dump... Are our Challenges and Opportunities still the same?


Mr Michael O'Kane

This paper asks the question, in essence: “Are the challenges and opportunities when building WRDs changing?” There are technical and financial perspectives in response to this question. For example, Canada's MEND Program highlights that over 50% of respondents from mine sites when surveyed have plans to collect and treat mine effluent into perpetuity. It is reasonable to assume that project economics of most, if not all, of these sites did not include the costs associated with this collection and treatment. This is not to say these projects did not provide economic value; rather, that the project economics were not optimized. In other words, the projects encountered unfunded and unrecognized liability associated with water quality issues. Ernest and Young, in their 2016-2017 assessment of the top ten business risks facing the metals and mining industry, place "cash optimization" at the top of the list (noting that it did not rank in the top ten in the previous year's assessment). The unfunded and unrecognized liability that mine operators and owners must manage into perpetuity due to effluent from waste rock dumps represents a substantial influence on "cash optimization". One can argue that a similar conclusion arises from Morgan Stanley's 2017 integration of Environmental, Sustainability and Governance (ESG) factors when analyzing investment opportunities in the metals and mining market. Management of water is one of four new ESG factors Morgan Stanley include in their 2017 assessment. From a technical perspective then, what are the new challenges and opportunities we face when planning a waste rock dump? This paper first sets the financial framework that allows us to "...Change the Question.." in regards to how we typically think about constructing waste rock dumps. Then, new and innovative technical solutions are discussed and case studies presented to illustrate a holistic approach for optimizing construction of waste rock dumps. The approach provides for the opportunity to substantially reduce, and more importantly defensibly quantify, waste rock dump stored acidity generation and release such that the risk of unfunded and unrecognized liability during operations and at closure is minimized. Case studies, including material characterization, numerical modelling, and field performance monitoring will be presented for sites in a variety of different climatic settings aroun