Sustainable landfill: the role of fail-safe engineering for landfill aftercare.

The route to sustainable landfill while adhering to the Landfill Directive requires that ultimately, the waste site will reach equilibrium status. Chemical equilibrium is part of the requirements, but hydraulic equilibrium must also play a role. The research described in this paper was examined the behaviour of a waste site as it approaches the end of its managed post- closure period. In particular, the possibility of leachate overtopping, and the balance between risk to groundwater (from high leachate heads acting on the liner system) and to surface water has been assessed. Passive fail-safe engineering is not related to uncontrolled or un-consented abandonment but requires careful prediction of the way the pre-installed features control the approach to equilibrium after active management ends.