Soil moisture profile of a water-shedding cover design in central Queensland

A soil cover isolates possibly acid-forming mine wastes from atmospheric interaction and thereby mitigate acid rock drainage. The availability of suitable soil cover materials is a problem, especially in arid/semi-arid environments where weathering rates are low. Moreover, these regions may be affected by monsoonal weather patterns adding a further challenge to soil cover design. This paper discusses an inclined soil cover configuration that constitutes waste rocks and blended tailings. The materials' hydrological properties were determined from in situ measurements and laboratory experiments. Preliminary results of the numerical modeling of its soil moisture profile indicated that a rocky substrate approaches near-saturated conditions during rainfall events but the use of blended tailings as hydraulic barrier may enhance lateral drainage, thereby reducing deep drainage. Consequently, the description of the transient soil moisture flow of this soil cover configuration will be validated by field data sets during the wet season.