SRK has successfully conducted a feasibility study of medium and long term solutions to infiltration and water management problems for one tailing storage facility (TSF) located in the central valley of Chile.
Monitoring wells in the region identified the problem with this TSF is that sulfate concentration has increased in the aquifer. The problem is exacerbated by an increase in the volume of the supernatant pond; therefore, actions to increase water consumption or removal of the contaminant need to be implemented.
The group of specialists SRK assembled to face this challenge included geotechnical engineers from SRK Chile, and off-shore SRK Australia tailings and geochemistry specialists.
Possible solutions the team analyzed to control infiltration and increase the consumption or reduction of the contaminant in the supernatant pond included: control of pollution sources, control of contaminant migration, and decontamination by means of collection and water treatment. The solutions studied included the use of thickened tailings, forced evaporation, evaporation ponds, and evapo transpiration, increasing the size of the clear water pond, sealing the impoundment, moving the pond, as well as hydraulic barriers, physical barriers, recycling water to the plant, introducing reactive permeable barriers and different types of treatment plants to reduce the concentration of sulfates.
Key activities for this study were verification of the effects of each solution, studying the combination of solutions on the expected volume of clear water pond and the expected sulfate concentration in the aquifer. For this purpose, the team developed and calibrated a monthly model for monitoring water balance and also one for contaminants. These tools permitted us to recognize the effectiveness of the solutions proposed.
Finally, the team developed a strategy to implement the solutions to keep contaminant levels under the maximum allowed. As a final solution, we suggested sealing the impoundment using a impervious cover made of a compacted mix of tailings and alluvial material over the natural field that will be in contact with the pond, forced evaporation and installing a treatment plant.
