This paper looks at how the design of the Hecla Greens Creek Mine was influenced by and responded to the constraints imposed by the development, placement and operational challenges discussed in Part I of this case history. Design issues such as static and dynamic stability, surface water and groundwater management need to be sufficiently robust to deal with the practical constraints described in Part I. The basis for successfully overcoming these challenges was characterizing the physical behavior of the tailings which differs from a natural soil of similar gradation. Key issues to be dealt with include climate (rain and snow), tight space restrictions leading to limited placement zones, over-wet tailings, minimizing the use of expensive imported materials, seismic response and dealing with heterogeneous glacial, marine and lacustrine foundation conditions. An interesting feature of the Greens Creek tailings is the apparent time related strength gain in the material which greatly improves the dynamic performance of the material.
Butikofer, D., B. Erickson, A. Marsh, R. Friedel, L. Murray and MJ. Piggott. 2017. “Filtered Tailings Disposal Case History: Operation and Design Considerations Part II.” in Proceedings, International Conference on Tailings and Mine Waste, Banff, Alberta, Canada, November 5-8, 2017. Edmonton, AB: University of Alberta Geotechnical Centre, 2017.
For Part I in this two-part paper, click here.