GEOTECHNICAL CHARACTERISTICS OF SYNTHETIC MUNICIPAL SOLID WASTE FOR EFFECTIVE LANDFILL DESIGN

Abstract

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/m3 for both Modified AASHTO and 4x Modified
AASHTO compaction methods, while angle of shearing resistance for Modified AASHTO compaction method
was 42.40
, and 48.50 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/m2. this complies with the results reported in
literature. Compression index (cc) was 0.4, initial compression ratio (r0) was 0.19, primary compression ratio (rp)
was 0.71 and secondary compression ratio (rs) was 0.10. These provide the necessary information needed for the
computation of expected settlement in the landfill.