Engineering properties of municipal solid waste

Mechanical behaviour of the waste body controls many aspects of landfill lining system design and performance, including stability issues and integrity of the geosynthetic and mineral lining components. Knowledge of the likely ranges of waste mechanical properties is required to assess potential modes of failure and hence to design the landfill engineering measures. This paper provides a summary of measurement and interpretation issues for the key engineering parameters used to define: unit weight, compressibility, shear strength, lateral stiffness, in situ horizontal stress and hydraulic conductivity. The topic of waste mechanics is developing rapidly and many papers have been published on waste mechanics, reporting results from both laboratory and in situ studies. Although waste is heterogeneous, many of the studies show that municipal solid waste has mechanical properties that vary in a consistent and predictable way (e.g. with respect to stress state and method of placement). An internationally agreed classification system and test standards are required to allow interpretation of published results. This will lead to development of appropriate constitutive models for waste and hence to optimization of landfill designs by considering waste/lining system interaction in full.