GaRDS – Avoiding Acid Drainage from Underground Mines

GaRDS is a new approach devised for preventing acidic drainage from underground workings. GaRDS stands for Gas Redox and Displacement System, and involves the displacement of air from underground workings with a bacterially generated gas mixture which ensures that sulphides do not decompose. The GaRDS approach was jointly devised and developed by scientists at Earth Systems and ANSTO’s Environmental Chemistry Division (an Australian federal government research agency).

The only other method of controlling ongoing sulphide oxidation in underground workings at present is to flood the workings once mining ceases. This approach is not appropriate to all sites and has several major drawbacks. Flooding is often not possible throughout a mine since it requires the installation of one or more pressure bulkheads. High costs of implementation and the substantial risk of catastrophic failure add to its unpopularity.

The GaRDS technique has significant advantages for mine operators who wish to temporarily close a mine, implement a low-cost and passive acid drainage prevention strategy, and retain the option of reopening the mine if metal prices increase. This approach is fully compatible with current ARD strategies of covering waste rock dumps or closing underground mine openings. Implementation of GaRDS is designed to rapidly improve drainage water quality emerging from enclosures, and prevent further sulphide oxidation.

A comprehensive paper outlining the technique is available (GaRDS.pdf). If you have any queries regarding this approach, or potential applications, please call Earth Systems for further information or contact us on




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