Geotechnical Aspects Of Landfill Closure And Aftercare

Abstract

Municipal solid waste landfills are geotechnical structures. Essentially, they may be regarded as containments which serve the purpose of preventing harmful contaminants from migrating out of the waste pile towards the environment, menacing the bases of life in nature, surface water, ground water and the atmosphere. Inside the landfill municipal solid waste undergoes processes of bio-degradation associated with considerable volume changes and the generation of gas and leachate. During the phases of waste disposal, closure and aftercare the processes inside the waste fill, their effects on the components of the landfill structure, lining systems, drainage facilities and gas collectors, are monitored, and improvements or repair can be carried out conveniently, when necessary. However in the long-term, the landfill shall reach a stable condition, which requires no further observation, so aftercare can be rescinded. It may take long time to reach this desired final condition. Concepts for in-situ treatment of municipal waste during the closure- and aftercare phases may enhance bio-degradation by controlled gas extraction and leachate infiltration. For the time beyond the aftercare phase, the landfill has to be provided with a cover system, which functions adequately and reliably long-term under site-specific ambient conditions. When all pertaining specified technical criteria with respect to emissions, deformations and overall stability are met, the responsible competent authorities may establish that aftercare is complete, and the landfill can be released from aftercare.