The effect of particle size distribution on hydraulic permeability in a waste mass

Abstract

In the waste management hierarchy, the least preferable option is waste disposal. Nonetheless, disposal is an integral part of any waste management system. In a landfill, during waste degradation processes leachate is formed that can potentially cause clogging of bottom drainage layers. To ensure stability of landfill construction, the physical properties of its components have to be controlled. In a landfill, waste presents the largest structural element and often controls both the stability and integrity of the lining system. The hydrology of precipitation, evaporation, runoff and the hydraulic performance of the capping and liner materials are important controls of the moisture content. It is important to understand the hydrology of a landfill site as it affects sustainability of landfill leachate management system. The water balance also depends on waste characteristics and waste particle size distribution. Waste characteristics are closely related to the waste composition in a landfill. The aim of the study is to determine the hydraulic permeability in a landfill depending on the particle size distribution of municipal solid waste disposed. Samples were taken from a landfill operating for five years. The samples were sorted to obtain fractions with differing particle sizes. The largest fraction of the waste was within the size-range of 20–100mm. The permeability test was conducted using the column test. The paper presents the results of the test indicating higher permeability with larger waste particle size.