ANALYSIS OF BREAKTHROUGH CURVES AND PERCOLATION PARAMETERS OF SUB-TROPICAL CLAYEY SOILS-AMD INTERACTIONS

Increasing climatic changes, exhaustion of natural resources from mining and similar activities, and the insistent growth in population have caused various human and environmental problems. Acid mine drainage (AMD) from mining operations in South Africa and around the world has been known to contribute a number of severe environmental challenges presently in need of dire attention. Pollution and/or contamination from AMD presents a serious risk requiring prevention and mitigation approaches for arresting consequential impacts on environmental and human health. The persistent human and environmental challenges based on AMD problems, created the impetus for the study to investigate the breakthrough curves and percolation parameters of two soils- Kaolinite, Halloysite and Illite/Vermiculite mixed layer (Soil A) and Kaolinite (Soil H) subtropical clayey soils interacted with AMD towards establishing their mineral buffering efficacy for use as natural contaminant barriers in areas under AMD attack. Successive prolonged percolation up to 24 pore volume passage of AMD through the respective soil media were carried out. The results of the study showed that after approximately 2.4 pore volumes of 0.01N CaSO4, baseline hydraulic conductivities of 1.3 × 10−11 m/s and 2.6 × 10−11 m/s were obtained for both soils respectively. After AMD infusion, their respective values were found to be within the accepted criterion of 1 × 10−9 m/s specified for clay/clayey liner construction in South Africa.