Hydraulic properties of household waste and implications for landfills

Abstract

A series of tests has been carried out on crude unprocessed household waste in a large purpose-built compression cell, to investigate the variations in density, drainable porosity and hydraulic conductivity with vertical stress. An increase in the particle density of the waste with increasing stress was identified; this may mean that the applicability of some standard soil mechanics theories to household waste may need to be reviewed. The results of the tests are described and discussed, with reference to their implications for the flow and control of leachate in landfills. The hydrogeological limitations on vertical flushing rates in landfills operated as flushing bioreactors are considered and the operation and performance of leachate extraction wells investigated by means of simple analytical models.

Development and evaluation of a phase relationship for MSW

“…One-dimensional compression tests have been carried out on real and artificial MSW samples to investigate volume change behaviour (Landva et al, 2000;Langer, 2006;Powrie and Beaven, 1999). Most of these tests were conducted under drained conditions and over a short time period so that significant biodegradation would not have occurred.…”

“…volume reduction of the components). Powrie and Beaven (1999) conducted 1D compression tests on unprocessed UK household waste in a large compression cell (2 m diameter, height 3 m). Detailed test data were reported for a specific waste sample called DM3, including total sample volumes and void ratio values at different vertical stresses.…”

“…The results showed that the curve of vertical strain against the logarithm of vertical stress has an almost linear relationship, which is identical to observed soil compressive behaviour, while the void ratio curve showed a very highly non-linear relationship. Powrie and Beaven (1999) attributed this to the existence of compressible particles in the MSW sample. In fact, volume compression of these particles was identified in the test, but further investigations have not been carried out.…”

“…This paper discusses and demonstrates the influence of compressible particles in MSW on its mechanical behaviour by considering MSW compression test results reported in the literature (Langer, 2006;Powrie and Beaven, 1999). A phase relationship for MSW is proposed by including compressible particles in the classical soil phase relationship and this is applied to the boundary condition of a 1D compression test.…”

“…A phase relationship for MSW is proposed by including compressible particles in the classical soil phase relationship and this is applied to the boundary condition of a 1D compression test. The proposed MSW phase relationship is evaluated by analysing the compression test data reported by Powrie and Beaven (1999).…”