Approaches to remediation of acid mine drainage water in pit lakes

Abstract

Pit lakes (abandoned flooded mine pits) represent a potential liability or valuable water resource to mining companies, the environment, and regional communities. However, water quality in the pit lakes can often restrict end uses for the water, particularly if affected by acid mine drainage (AMD). Nevertheless, various and diverse treatment strategies now exist for remediating the water quality of these significant post-mining landscape features. Backfilling of the pit may prevent the formation of a pit lake, or may be important in determining the final pit lake shape and bathymetry. Fast filling or contrived lake stratification may also reduce the extent of pyrite oxidation and hence acidity production. Some “active” remediation technologies such as direct liming of pit water are well-proven and effective, but may be expensive to maintain following mine closure and lease relinquishment. Alternatively, other approaches are using “passive” remediation techniques such as stimulation of primary production and sulfate reduction to improve pit water quality. Although there is much promise, there remains great scope for research and monitoring in this multidisciplinary field, before this science can be relied upon for long-term prediction of water quality pertaining to the liability of current and planned pit lakes.

Keywords:

• Pit lakes
• Acid mine drainage
• AMD
• Remediation
• Heavy metals
• Water quality

Acknowledgements

This work was funded under the Centre of Excellence for Sustainable Mine Lakes (a Western Australian State Government initiative) and was supported by the Centre for Ecosystem Management at Edith Cowan University.