Determination of optimum clay thickness for minimizing leachate permeability of a waste disposal dumping site in Turkey

Disposal of solid waste is a challenging task in developing countries as this type of waste can seriously degrade the environment and pose threat to human health. To mitigate the environmental impact, appropriate techniques must be used in accordance with standards for the disposal of solid wastes. Leachate that originates from the decomposition of solid waste within waste disposal dumping sites and landfills may infiltrate into soil, groundwater and surface water resulting in contamination. A combination of clay materials and geomembrane has been widely utilized as a suitable permeability barrier to prevent contamination. In the case of uncontrolled landfills, leachatemay be responsible for serious and irreversible pollution. According to the standards utilized in Turkey, the thickness of the clay layer used as an impermeable material is 60 cm, which is constructed as two 30 cm thick compacted clay layers. This paper evaluates the optimum clay thickness to prevent leachate contamination of soil or water. Experimental models were prepared involving 20, 40, 60 and 80 cm thick clay layers with 20 cm height leachate to determine the optimum clay thickness permeability barrier for a waste disposal dumping site. The initial results indicate that a 40 cm thick clay layer is sufficient as an impermeable barrier in these sites.