Compressibility Characteristics of Open Dumped Municipal Solid Waste in the Dry Zone of Sri Lanka

Primary compression is known to be the major component in the settlement mechanism of Municipal Solid Waste (MSW). Presented in this paper are results obtained using a modified large-scale oedometer describing the primary compression characteristics of MSW dumped at the Hambantota open dump site in Sri Lanka. Samples from varying depths were extracted from the dump site to evaluate the compressibility characteristics of MSW in order to expand the existing dump site to landfill. The dumping area was divided into two categories corresponding to the age of the fill. Compressibility and composition of old (10 years) and new (2 years) waste showed similar characteristics. One-dimensional confined compression tests were conducted for shredded MSW recompacted at field densities. The compression index Cc was observed to vary from 0.15 to 0.27. However, after normalization by the initial void ratio e_o, the modified compression index C_c’ varied in a narrow band between 0.08 and 0.11, signifying that C_c’ is the more suitable parameter to predict primary consolidation settlement of solid waste dump sites.