January 2011
In Sri Lanka, engineered landfills are not usually available and the common procedure is to cover the waste with a good cover soil without providing gas venting facilities. Hence, hazardous gaseous and liquids from landfills emit through this cover soil. Therefore, studying the cover soil parameters are of paramount importance in evaluating its future gas diffusion. The Soil gas diffusion coefficient (D p) and Air permeability (k a) govern the transport and emission gases in the unsaturated zone. In this study, soil gas diffusivity (D p/D o, D o is gas diffusion coefficient in free air) and k a were measured for the final cover soil of Maharagama landfill at different soil water matric potentials. k a and D p/D 0 were measured as a function of air filled porosity (s) at different water contents. Finally, it is concluded that final cover soil of Maharagama waste disposal site is a material very low gas exchangeable capacity ie it is a good capping soil.