Triaxial Permeability Testing on the sythetic Leachate Effect on the Hydraulic Conductivity of Clayey Soil

Triaxial permeability apparatus with the fabricated bladder accumulators were used to examine the effect of synthetic leachate on the change of hydraulic conductivity of clayey Soil . A silty clayey sand sample was obtained from Urmia City landfill site and mixed with 12% clayey soil to obtain a soil with optimal characteristics suitable as a liner material for landfill. The synthetic leachate was prepared with there different Ca++ concentrations concentrations were used is synthetic leachate and the hydraulic conductivities of 1.33*10-8 cm/s, 1.81*10-8 cm/s, and 1.77*10-8 cm/s were obtained for the soil permeated with synthetic leachate, compared with the average hydraulic conductivity of Ca++ contraction caused about 13% reduction in hydraulic conductivity in the first test which could be due to decrease in void ratio because of consolidation of the sample induced by osmotic flow. The percentages of increase of hydraulic conductivity for two other tests in comparison with the values for tap water permeation were 18% and 20% respectively. This increase is attributed to double layer contraction and increased pore space, resulting from the adsorption on divalent cations into the soil matrix.

Keywords:

Triaxial permeability , Hydraulic Conductivity , Synthetic leachate , Calcium