Hydraulic barrier properties of soil beneath Egbedi active municipal solid waste dumpsite

Abstract

This study researches the potential of soil underlying an active municipal solid waste dumpsite as compacted clay liner in municipal solid waste repository structure. Identification of soil samples and their chemical constituents was conducted. Ex-situ tests were conducted in the laboratory to obtain three important hydraulic barrier parameters: coefficient of hydraulic permeability (k), volumetric shrinkage strain (VSS) and shear strength (UCS) of the natural soil samples employing three compaction techniques namely; British Standard Light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). Soil specimens were also prepared with varying moulding moisture contents −2%, +2 and + 4 % of optimum moisture content (OMC). The microstructure of the natural specimen was investigated via scanning electron microscopy. The natural samples were identified as; A-2-7(0), A-2-7(2) and A-7-5(5) for sample A, B and C respectively according to AASHTO classification while all samples are classified as SC (Clayey Sand) according to USCS classification. The moulding moisture content that satisfy the k and VSS conditions of k ≤ 1.0 × 10−7 cm/s and VSS ≤ 4 % falls between 9.63 – 17.68 % and 9.63–12.75 % respectively, but the tested specimens fall short of strength condition. This study revealed that the natural soil samples fail to fulfil the design parameter requirements for strength in its application as liner/cover in the active waste dumpsite, therefore further investigation to ameliorate the strength property of the soil samples using additives or microbial induced calcite precipitation (MICP) technique is recommended.