The geochemical engineering of landfill liners for active containment

Abstract

Abstract The performance of engineered containment barriers presently used to line UK landfills is uncertain over the design lives of most sites. Failure of key components of the barrier technology can be expected within a timescale under which leachate will still present a threat to groundwater resources. Additional environmental control measures are therefore necessary to mitigate the effects of these future impacts. A methodology for the geochemical engineering design of high-attenuation landfill liners using low-cost natural and industrial waste materials which are available in the UK is presented. Anaerobic laboratory column experiments are used to test the performance of various materials as liners in chemically attenuating contaminants in a methanogenic leachate spiked with a suite of heavy metals and organic micropollutants. The basic liner design recipe which maximizes the attenuation of key contaminants in leachate has been confirmed. Variability in material composition does not significantly affect liner performance provided this recipe is used. Important design issues (liner exhaustion and attenuation reversibility effects) are examined in the study. These liners may be routinely constructed from measurements of a limited suite of material properties using standard laboratory procedures. The application of these liners within the current framework of landfill design is outlined.