Effect of grain size on service life of MSW landfill drainage systems

Abstract

A numerical model “BioClog-2D” is used to examine the service life and clogging of leachate collection systems with granular drainage material of different grain sizes. The modelling shows that the leachate characteristics at the end of the drainage pipe are significantly different from those in the leachate entering the leachate collection system and this reduction in leachate strength corresponds to an accumulation of clog mass within the saturated drainage layer. The calculated clog mass within the saturated drainage layer is dominated by the inorganic material, which is in encouraging agreement with field-observed data. The service life of leachate collection systems is increased with an increase in the grain size of the drainage material and decreased with an increase in the length of the drainage path. The service life of the drainage layer is shown to vary from a few years to over 100 years depending on the design of the system. The results indicate that in addition to the particle size of the granular material, the infiltration rate and leachate strength history greatly affect the estimated service life of leachate collection systems.