Development of a multi-criteria decision analysis tool for the assessment of the potential pollution risk of tailings dumps to the environment – An approach validated using selected Zambian Mine tailings

Abstract

Mine tailings have a huge footprint on the environment and can have serious consequences that are difficult to reverse during mining operations or even long after mining has ceased. Despite several studies that have been conducted on tailings dumps, effective impact assessments of their potential pollution risk have been a challenge. This challenge can, to a certain extent, be attributed to the lack of identification of a common criterion for risk classification to items of environmental concern (people, natural landscapes, and their components) including the absence in consideration of time frames. Consequently, this has made it difficult to conduct impact assessment studies of mine tailing dumps. This study assessed the potential pollution risk of the dumps using a multi-criteria decision making (MCDM) tool called an Analytical Hierarchy Process (AHP). An appropriate criterion for risk assessment was developed with the help of experienced experts and weighted using an AHP methods. This enabled the determination of the potential pollution risk to the environment from three selected Zambian-based tailings dumps (i.e., Kabwe Lead–Zinc, Mopani Copper Mine and Lumwana Mine dumps) by means of a criterion scoring technique developed. Five key indicators were adopted that included: 1) physical properties; 2) soil chemical accumulation; 3) properties of the environment around the dump; 4) climatic factors around the dump area; and 5) protective structures. Specific factors per indicator were identified using expert opinion and experiences. Results of the analysis revealed that the Kabwe Mine tailings dump had the highest pollution potential followed by the Lumwana Mine and then Mopani mine tailings dump when compared against severity of risk scale. The tool was then validated using a tailing dump at Musina Copper Mine, in South Africa, where a different approach was previously used and this tool showed comparable results. Accordingly, this decision support tool can be used by environmental management agencies during the environmental impact assessment (EIA) review processes to improve efficiency in investigating scenarios that would propagate contamination and thus improve environmental management interventions.