Evaluating the improved hydraulic conductivity of double layer liners by bentonite and DCP

Soil and groundwater contamination due to leachate from municipal solid waste landfills is one of the most important environmental challenges for management of soil and water resources. This study was aimed to propose a landfill liner from the existing natural materials that in addition of having proper permeability, provides more capacity to absorb leachates. Two natural amendments including bentonite and DCP were applied to coarse landfill soil of Evaz city in Fars province between zero to a maximum 9% and 0.2% of base materials dry weight, respectively. The required permeability tests were conducted with both water and synthetic leachate. Results indicated that for the materials containing 6% bentonite, application of 0.2% DCP was considerably reduced the permeability compares to the bentonite application. Due to larger viscosity, the permeability of synthetic leachate in base liner materials and containing 3% bentonite, was less than the water. However, in the 6% bentonite application, due to its acidity, the permeability of leachate was increased. In 9% bentonite, synthetic leachate had minor effect in reducing or increasing the soil permeability. This can be attributed to significant increase of fine particles and the increase of soil buffering properties.