Evaluation of a geosynthetic capillary barrier

This paper introduces a new type of geosynthetic product, namely a geosynthetic capillary break (GCB) which provides a similar functionality to that of a traditional soil capillary break. This new product, manufactured similar to a geosynthetic clay liner and composed of non-woven geotextiles needle-punched on both sides of a fine-grained material can be used as part of an engineered cover system to reduce oxygen transport and net percolation in potentially acid generating mining wastes.The unsaturated hydraulic properties of the geotextile, fine-grained rock flour, as well as cover soil and mine tailings were determined in order to develop a set of inputs for a numerical model of an engineered cover system. The results of the modelling showed that the inclusion of the geosynthetic capillary barrier (GCB) acts to decrease suction developed in the overlying cover materials during drainage. This increased pressure head allows the overlying materials to remain at a higher degree of saturation, potentially reducing both oxygen and moisture ingress into the waste.