A Study Of The Effects Of Municipal Landfill Leachate On A Basaltic Clay Soil

The performance of a landfill clay liner is generally evaluated using the hydraulic conductivity values obtained from laboratory tests during the design stage. Laboratory tests for the determination of hydraulic conductivity are frequently carried out either using water as the permeating liquid or some times using a chemical permeant to represent leachate. However, any investigations incorporating time as a variable in analysing the effects of leachate on various other soil properties that can influence the hydraulic conductivity are very limited. This study is aimed at investigating the effects of landfill leachate on the performance of a compacted basaltic clay soil, over a period of time. For this purpose, a typical Melbourne basaltic clay with varying percentages of montmorillonite clay was selected and a synthetic leachate was developed based on the composition of typical municipal waste landfill leachate reported in the literature. The clay – leachate interactions were allowed take place under controlled anaerobic laboratory conditions. Samples were then tested at different time periods to identify possible variations of engineering properties such as volume change, consistency and grain size distribution due to the effect of leachate over time, since variation of these soil properties can affect the hydraulic conductivity of a clay soil. The analysis of test results suggests that the behaviour of a basaltic clay liner could be significantly affected by clay leachate interactions over time, due to possible alterations to physical and mineralogical properties of the clay.