Assessment of Performance for Alternative Cover Systems on a Waste Rock Storage Area

A cover is usually applied to the top of the mining wastes to prevent exposure of sulphide minerals in the waste to water and oxygen ingress in order to mitigate the unwanted consequences such as acid rock drainage. Hence, the selection and design of the appropriate cover system by considering the climatic conditions, local unsaturated and saturated properties and the availability of the cover materials become an important issue. This study aims to investigate the performance of various cover systems and designs for the North Waste Rock Storage Area in Kıșladağ Gold Mine located in Ușak in Western Turkey. SEEP/W and VADOSE/W softwares are used to model the flow in unsaturated and saturated zones and to assess the performance of various cover systems. The soil water characteristics and parameters used in the model for saturated and unsaturated conditions were taken from field tests and literature. Accuracy of input data is checked during calibration for steady state conditions with SEEP/W. Then, bedrock, waste rock and cover alternatives are modeled under transient conditions for 20 years using daily climatic data. The effectiveness of the various cover systems for minimizing the ingress of water and air that cause acid rock drainage is evaluated and recommendations are made so that the impacts to groundwater from the waste rock storage areas during closure period are minimized