How are tailings dams built and operated?
Conventional methods Tailings dams are built using one of three methods: upstream (cost-effective but more hazardous), downstream (more stable, higher cost), or centerline (a balanced approach).
Tailings dams are built by preparing the site, selecting suitable materials, and constructing zoned walls; often with a rockfill shell and clay core to control seepage and ensure stability. Tailings are deposited as slurry in controlled layers, with drainage systems managing water flow.
Operating a tailings dam generally involve the following:
- Deposition of the tailings slurry to develop and manage a beach that supports and controls the supernatant pool
- Managing the supernatant pool using the decant system
- Continuous monitoring for movement and seepage, water level control through decant systems and spillways, and regular maintenance to prevent erosion.
- Environmental safeguards ensure the dam remains structurally, chemically, and hydraulically stable.
Operating a tailings dam requires careful planning and resourcing, and careful oversight. Since a tailings dam is continuously filled from the day it is commissioned to the day it decommissioned, the risks and hazards associated with it generally increase with time until it closed, which is contrary to most engineering structures. Having continuous engineering oversight (such as from the Engineer-of-Record, and Responsible Tailings Facility Engineer) on these structures is a vital component to their continued safety.
