One-dimensional analytical model for contaminant transport through CCL under thermal diffusion and its application

A one-dimensional analytical model as well as the analytical solution for the contaminant transport in compacted clay liner (CCL) is proposed. The dimensionless design curves show that the advection has significant effects on the contaminant transport in CCL. However, with the increases of thermal diffusion, the effects of the advection will decrease. The results of parameter sensitive analysis show when the leachate head reaches 3 m, the 10-year bottom concentration and flux increase by the factors of 3.5~4.9 and 5.9~15.1, respectively, compared with those without the advection. When the thermal diffusion is great enough (M=-5), the bottom concentration and flux increase by the factors of 2.6 and 3.5, respectively, compared with those without the thermal diffusion. The effects of the temperature on the permeability coefficient of CCL should be considered in the design of landfill clay liners. A simplified method for determination of the thickness of the landfill liner is proposed. The simplified method is used to design the liner system at the Jiangcungou Landfill site in Xi 'an. When considering the chloride (Cl^-) and arsenic (As) as the index contaminants, the breakthrough time will be longer than 50 years in the case with the thickness of CCL larger than 11.16 m and 1.75 m, respectively.