One of the major problems affecting municipalities is solid waste management. There is a difficulty in selecting suitable sites for waste disposal as it involves different factors to be considered before site selection. Currently, waste generation in Johor Bahru has steadily increased over the last few years and the only existing sanitary landfill is reaching its capacity limits, which means that a new sanitary landfill site needs to be constructed. In this study, geographic information system (GIS) and analytical hierarchy process (AHP) methods were utilized with the integration of dynamic data such as future population and projection of waste production in order to provide suitable sites for the construction of a sanitary landfill in the study area. Thirteen criteria were considered for this study, namely water bodies, soil, geology, slope, elevation, residential areas, archeological sites, airports, population, road, railway, infrastructure, and land use. AHP was used to determine the weights for each criterion from the pairwise comparison matrix. Consistency index and consistency ratio were checked and confirmed to be suitable. The results obtained from AHP were assigned to each criterion in GIS environment using weighted overlay analysis tool. The final potential site map was produced, and the three most suitable potential landfill sites were identified.

As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic columns to provide a clear visualization of leachate migration into the soils. Digital image technique was used in capturing photos at successive time intervals to monitor the leachate migration. The captured digital images were fed into Matlab and converted into hue-saturation-intensity (HSI) format. Surfer software then read the HSI and generated 2D contour plots. The results of the experiments showed that the leachate moves downward faster in the soil gradation with the least fines content. Hydraulic conductivity values decrease with increase in time duration and equally with increase in fines content. The hydraulic conductivities of the leachate for 30%, 40% and 50% fines were 3.64×10-9m/s, 2.40×10-9m/s, and 1.24×10-9m/s respectively. This reveals that for tropical laterite soils, gradation containing 50% fines content provides better hydraulic conductivity. The use of noninvasive digital image technique can enable designers/engineers to monitor and visualize the leachate migration in compacted soils in waste containment application systems.

Abstract. The study area forms part of the precambrian to early paleozoic Nigerian Basement Complex. The Nigerian Basement Complex is a polycyclic assemblage of heterogeneous migmatites and gneisses, metasediments and granites that have undergone a complex evolutionary history spanning through Archaean to Pan-African (Late Proterozoic) times. Multispectral images from Landsat 7 ETM+ were utilized to complement field mapping, elucidate lineaments and clearly outline alteration zones. The dominant rock types in the area are gneiss, granites and metasediments with minor lithologies such as aplite dykes, quartzofeldspathic and quartz veins, pegmatites and xenolith. Petrographic studies have shown that the granite comprises of porphyritic and medium to coarse grained varieties that are composed mainly of quartz, feldspar, biotite ± muscovite. The metasediments include pelitic schist and composed of quartz, biotite, feldspar, ± muscovite, ± chlorite and quartzites. These rocks have been deformed, sheared and foliated. The dominant NW-SE to N-S structural trend, follows the general trend of structures resulting from both Pre-Pan-African and Pan-African Orogenies. The geological and structural maps of the study area on a scale of 1:50,000 have been updated.