Suit Ability Analysis For Solid Waste Landfill In A Geospatial Technological Environment For Ibadan Metropolis, Oyo State, Nigeria

ABSTRACT.

Municipal solid waste landfill is an important part of the urban infrastructure that ensures the

protection of environment and human health. Landfill selection problem for municipal solid

waste involves many factors, criteria and regulations. The aim of this study is to access suitable

site for an engineered solid waste landfill, ·with specific objectives of site determination based on

UNEP criteria and carrying out both geophysical and geotechnical evaluation of the site. The

study area is Ibadan metropolis. Geographical Information System (GIS) based methodology

was applied in order to identifj; and select potential suitable sites. The initial step of the

methodology comprises a GIS application and analysis that exclude all areas unsuitable for any

waste disposal facility. Using the GIS spatial analytic model different constraint map layers were

overlaid to obtain a potential suitability map. The output suitability map represents possible

potential sites that are suitable for landfill sites. Geophysical and geotechnical survey were

carried out on one of the site for the purpose of sub-surface characteristic of the site and the

strength of the soil as a foundational material to be used for landfill design. Vertical Electrical

Soundings (VES) with electrode spacing of J 00. OOm apart were executed to obtain subsuiface

information on depth to bedrock and ground water table. The VES results indicate there are four

geo-electric layers with depths of bedrock to basement rock to between 18. Om and 55. Om which

represents potential ground water accumulation.

Disturbed and undisturbed soil samples were collected at vertical interval of 0.5m up to a depth

of 4. OOm. The soil samples were subjected to geotechnical parameter namely grain size

distribution, consistency limit test, and permeability test. The soils possessed amount of fine

materials (1 3.1 - 73. 0 %) and clay content (4.3 - 38. 7 %) that are within the minimum 30 % and

10 % respectively considered adequate for a landfill site. Furthermore, they are well-graded

exhibiting low to medium plasticity with plasticity index of 2. 9 to 20. 3 % and low leakage

potential of 2. 7 x 10·3 to 9. 26x 10-3 cm/s within the depth of 4m. Permeability coefficient (k)

rangedjrom 4. 7 X J o-B to J. 9 X 10-6 cm/s and was within the range of 1 o-B to 10-6 cm/s which fa/ls

within the optimum permeability range for leachate retenti