Suitability of Soft Clay as Clay Liner based on Clay-Leachate Interaction Studies

Waste Disposal in urban areas with dense population is a challenging problem for a developing country like India. Although there are other methods for waste disposal (Recycling, Composting, Incineration), it is generally accepted that landfill is the most cost effective disposal method. This has the advantage of putting useless land to reclamation. Previous studies shown that clay compacted to a permeability of less than10 -7 cm/sec form a good barrier to leachate and also cost effective. The present work in this area has two aspects viz., suitability of local soils from stability and permeability characteristics for use as landfill clay liners and study on clay-leachate interaction using soft clay as clay liner. The basic properties like Liquid limit (LL), Plastic limit (PL), Free swell index (FSI) and pH are discussed in terms of physicochemical aspect. Certain mineralogical and microstructure studies undertaken on this interaction phenomenon are also presented. It is concluded that organic chemicals presented in the leachate destroy the double layer properties of soft clay and reduce the plasticity of the soils. Formations of some new clay minerals are observed in X-ray Diffraction graphs and formation of aggregates and flocs are observed in scanning electron micrographs.