Moisture retention curve in landfilled waste

Moisture content and moisture movement are key factors in controlling the progress and rate of biodegradation within a landfill as it is the aqueous environment that facilitates the transport of nutrients and microbes. The modelling of infiltration and water movement requires information on the moisture retention and hydraulic conductivity properties, usually in the form of empirical functions such as those proposed by van Genuchten (1980). In waste however, the particle and pore size distribution, heterogeneity of waste composition and leachate chemistry complicate the determination of moisture retention and hydraulic conductivity. In this paper we describe the modification and use of a standard pressure plate apparatus to establish moisture retention properties of samples of 250 mm in diameter and the difficulties of using this method. Some initial results are presented.