Long-Term Performance of a ''Store/Release'' Cover over Potentially Acid Forming Waste Rock in a Semi-Arid Climate

Abstract

The reclamation of potentially acid forming waste rock is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed and, importantly, the climatic setting. The "store/release" cover developed to manage acid rock drainage from mineralised waste rock dumps at Kidston Gold Mines' open pit operations in the semi-arid, seasonal, sub-tropical climate of North Queensland, Australia, has been monitored for up to 9 years. The paper describes the philosophy behind the store/release cover design and its adaptation over time to suit Kidston's conditions. The results of monitoring of the store/release cover system over 9 years are presented, and estimates are made of the water balance of the store/release cover for a range of annual rainfall totals and of the overall water balance of the waste rock dumps. The Kidston story is a valuable case study of a successful approach to remediating an identified source of acid rock drainage in a semi-arid climate, which has actively engaged all Stakeholders.