ABSTRACT
Drainage of leachate in landfills is mandatory in order to ensure the geotechnical stability of the waste and to prevent release of leachate into surface and ground water. Geosynthetics have during recent decades found increasing uses in landfill construction. Designing geosynthetic drainage systems can present peculiar difficulties and uncertainties when the hydraulic structures come into contact with wastes instead of natural soils. However, the increasing use of geosynthetics requires theoretical knowledge of the behaviour of geosynthetic drainage systems in waste landfills, the development of design criteria for practical applications. The design of the geosynthetic drainage system on slopes and the bottom of the landfill should therefore be done for the landfill in use. The discharge capacity can be given in terms of transmissivity, defined as the discharge per unit width of the geonet per unit of hydraulic gradient; or better in terms of specific flow-rate, defined as the discharge per unit width in the geonet, under a specified hydraulic gradient.
