title: Leachate flow around a well in MSW landfill: Analysis of field tests using Richards model.
abstract: During the lifespan of a Municipal Solid Waste landfill, its leachate drainage system may get clogged. Then, as a consequence of rainfall, leachate generation and possibly leachate injection, the moisture content in the landfill increases to the point that a leachate mound could be created. Therefore, pumping the leachate becomes a necessary solution. This paper presents an original analysis of leachate pumping and injection in an instrumented well. The water table level around the well is monitored by nine piezometers which allow the leachate flow behaviour to be captured. A numerical model based on Richards equation and an exponential relationship between saturated hydraulic conductivity and depth is used to analyze the landfill response to pumping and injection. Decreasing permeability with depth appears to have a major influence on the behaviour of the leachate flow. It could have a drastic negative impact on the pumping efficiency with a maximum quasi-stationary pumping rate limited to approximately 1m3/h for the tested well and the radius of influence is less than 20m. The numerical model provides a reasonable description of both pumping and injection tests. However, an anomalous behaviour observed at the transition between pumping and recovery phases is observed. This could be due to a limitation of the Richards model in that it neglects the gas phase behaviour and other double porosity heterogeneous effects.
authors.affiliation: University of Skikda, Algeria; Laboratoire d'etude des Transferts en Hydrologie et Environnement (LTHE), Université Grenoble Alpes, BP 53 38041 Grenoble Cedex 09, France.
authors.forename: R
authors.initials: R
authors.lastname: Slimani
authors.affiliation: Laboratoire d'etude des Transferts en Hydrologie et Environnement (LTHE), Université Grenoble Alpes, BP 53 38041 Grenoble Cedex 09, France. Electronic address: laurent.oxarango@ujf-grenoble.fr.
authors.forename: L
authors.initials: L
authors.lastname: Oxarango
authors.affiliation: University of Badji Mokhtar-Annaba, Algeria.
authors.forename: B
authors.initials: B
authors.lastname: Sbartai
authors.affiliation: Laboratoire d'etude des Transferts en Hydrologie et Environnement (LTHE), Université Grenoble Alpes, BP 53 38041 Grenoble Cedex 09, France; Université de Lorraine (ENSG)/CNRS/CREGU, GeoRessources Laboratory, F-54518 Vandoeuvre-lès-Nancy Cedex, France.
authors.forename: A-J
authors.initials: AJ
authors.lastname: Tinet
authors.affiliation: ECOGEOS, Geoenvironmental Advisory Services, 5 rue du Jeu de Paume, 62000 Arras, France.
authors.forename: F
authors.initials: F
authors.lastname: Olivier
authors.affiliation: Laboratoire d'etude des Transferts en Hydrologie et Environnement (LTHE), Université Grenoble Alpes, BP 53 38041 Grenoble Cedex 09, France; Laboratoire Sol, Solide, Structure, Risque (3SR), Université Grenoble Alpes, BP 53 38041 Grenoble Cedex 09, France.
authors.forename: D
authors.initials: D
authors.lastname: Dias
mesh_terms: D060587:Groundwater; D008962:Models, Theoretical; D012037:Refuse Disposal / Q000379:methods*; D062611:Solid Waste; D064091:Waste Disposal Facilities; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D062611:Solid Waste; D014874:Water Pollutants, Chemical
keywords: Injection test; Landfill; Numerical modeling; Pumping test; Richards equation