Large-Scale Cover Trial of Tailings Dam, Heap Leach Facility and PAF Waste Dump at Nifty Copper Operation

Abstract

Nifty Copper Operation has three waste landforms with highly saline materials: tailings dam, heap leach facility and a PAF waste dump. Once rehabilitated, potential exists for salts from these wastes to rise via capillary action into the cover material. Two large-scale trial plots were installed on each of these landforms in June 2015 following preliminary water and solute balance modelling. The objectives of the cover trial are to measure the actual movement of water and salts within the cover layers and the underlying in situ materials.
Plots were established with different cover thicknesses on each landform. Specialised monitoring equipment was installed on each plot to monitor climate and soil moisture and salt movements through the cover profiles. Data was collected via wireless and cloud-based systems. Simulated rainfall was applied to the plots to expedite data collection and reduce the risk that insufficient rainfall events would occur during the short available trial period. Physical samples of the materials’ salinity and moisture (along with a suite of other measures) were taken to validate the data recorded by the electronic monitoring equipment.
These data provide a validation dataset used to complete long-term water and solute movement modelling, and in turn identify the cover design that would most effectively manage potential salt movement in the long term. Additionally, the data has been used to calibrate water-solute balance models, with outputs used to assess the long-term performance of the cover design. This case study details the initial modelling, cover trial set up, and a summary of the data collected.