Tailings ponds can occupy large areas due to the commonly low ore grades (99% of ore mass is waste). The main environmental and radiological concerns are:
| Concern | Description | Mitigation |
|---|---|---|
| Direct radiation | Gamma exposure from tailings pond surface | Distance, shielding, covering |
| Radon emanation | Rn-222 gas released from radium-226 decay | Water cover during operation; clay and topsoil cap after closure |
| Dust resuspension | Windblown radioactive particulates | Water cover, vegetation, fencing |
| Groundwater contamination | Leaching of radionuclides and heavy metals into aquifer | Lined ponds, monitoring wells, zero-discharge policy |
| Surface water contamination | Run-off carrying contaminants | Retention ponds, water treatment, evaporation |
During operation: The tailings are usually covered by water to reduce surface radioactivity and radon emission.
After closure: The tailings dam is covered with a layer of clay (to block radon) and topsoil (to support vegetation), reducing radiation levels to near natural background.
ISL Advantage: In situ leaching produces no tailings and very little waste, which is one of its major environmental benefits compared to conventional mining.