Tailings Pond Sedimentation Capacity: A Practical Approach

December 16, 2024

An important aspect of the operation of many conventional mine tailings storage facilities (TSFs) is providing sufficient tailings pond sedimentation capacity to meet total suspended solids (TSS) water quality requirements for direct discharge to the environment or reclaim for re-use in milling. While maintaining a larger pond volume/area will typically correspond to greater sedimentation capacity (i.e., residence time), minimizing the tailings pond size can be important for reducing the risk of the facility. For sites with negative water balances/water deficits (i.e., outflows and losses exceeding inflows), managing the TSF with a small pond and maintaining sufficient water for re-use in milling can be important for operational resilience and water conservation. Previous guidance has highlighted the challenges of purely theoretical approaches for the sizing of TSF pond areas for adequate sedimentation and have suggested “rules of thumb” for minimum pond sizing that tend to be conservatively large when compared to observed pond sizes for operational facilities.

This paper presents a summary of observed tailings pond sizes and reported mill throughput for several conventional TSFs across North America and South America, and a case study for a conventional TSF at an open pit copper mine. Based on the results of the case study and observations for other sites, a practical approach is presented for setting operational targets for pond sizing in terms of tailings production rates and estimated material settling velocities, and for assessing when additional TSS controls may be required (e.g., berms to increase flow path lengths, silt curtains, or filtered intake structures).

Louws, M., K. Stapleton, A. Witte, S. Nunoo and F. Niyazi. 2024. “Tailings Pond Sedimentation Capacity: A Practical Approach,” in Proceedings of the Tailings and Mine Waste Conference, 10-13 November 2024. Colorado, USA.