Rainfall simulator study of the erosion control potential of palm geotextiles for mine dam slope stabilization

Abstract

Mining has been the backbone of the South African economy since the late 19th century. Large volumes of mine waste, such as tailings, have been generated in some areas. Mine waste is highly susceptible to both water and wind erosion, it may create moderate to severe chemical imbalances or toxicities and has a severe abrasive effect on seedlings, a low water-holding capacity and is prone to compaction and crusting. Biogeotextiles are potentially effective and economically-viable erosion control products. The main objective of the study reported herein was to establish the erosion control properties of palm-mats by determining erosion-related variables via rainfall simulation. The textiles were manufactured from the leaves of the Lala palm (Hyphaene coriacea) and covered about 40% of the tailing surface. Ten representative samples of South African mine waste materials were collected for the rainfall simulator studies. Measured erosion parameters included; runoff, sediment load in runoff and interrill erodibility. Seven samples were sand-textured and three were silty. Sediment load was not dependent on exchangeable sodium or organic matter contents, but prominently associated with pH, silt percentage and the quartz content in the clay fraction. When the samples were covered with palm-mats the amount of runoff was similar to that of bare materials, but sediment yield was reduced by about 55%. These results confirm the suitability of palm geotextiles for erosion control on tailing dam slopes.