GEOTECHNICAL CHARACTERISTICS OF SYNTHETIC MUNICIPAL SOLID WASTE FOR EFFECTIVE LANDFILL DESIGN

This paper presents the results of laboratory investigation performed to determine the geotechnical characteristics of synthetic municipal solid waste (SMSW); simulating typical composition of municipal solid waste (MSW) generated in Akure metropolis, south-western Nigeria. It was generally observed that the unit weight, specific gravity and shear strength of the SMSW increased with increase in compactive effort. Direct shear tests gave cohesion value of 7.6kN/m(3) for both Modified AASHTO and 4x Modified AASHTO compaction methods, while angle of shearing resistance for Modified AASHTO compaction method was 42.4 degrees, and 48.5 degrees for 4x Modified AASHTO compaction. In design of landfills the least shear strength failure envelope should be used for effective design. The hydraulic conductivity for both compactive efforts were within the same order of magnitude indicating that the Modified AASHTO compaction was a good approximation of field compaction for the municipal solid wastes. Compressibility test on SMSW gave compression ratio of 0.20 with total compression of 33.0% under maximum load of 224kN/m(2). this complies with the results reported in literature. Compression index (c(c)) was 0.4, initial compression ratio (r(0)) was 0.19, primary compression ratio (r(p)) was 0.71 and secondary compression ratio (r(s)) was 0.10. These provide the necessary information needed for the computation of expected settlement in the landfill.