Numerical analyses of a leachate pumping test at a MSW landfill

This paper presents the results of a long-duration pumping test with variable pumping rate performed at a MSW landfill. Measurements of the surface settlement near the pumping well reveal that the pumping-trigged deformation of the waste behaves in a strong viscous manner. The hydraulic conductivity determined in this study varies between 4.5×10-7 -5.5×10-6 m/s with an anisotropic ratio of 10. Numerical simulations show quite significant discrepancies between hydraulic modelling (H) and the coupled hydraulic-mechanical (HM) modelling, with the latter performing much better than the former. This implies the necessity of incorporating the flow model in a deforming porous medium, and as a consequence the need to account for variable hydraulic properties as deformation proceeds.