Abstract
Waste management has taken the front purview in recent years due to the evident and attendant effects of indiscriminate disposal of wastes to the environment. This led to the preliminary investigations for the proposed siting of a landfill facility in Lafia and environs of Nasarawa State in Central Nigeria, with the aim of providing valuable information on the suitability for location for the disposal of Municipal Solid Waste (MSW). The combined use of geo-resistivity, geological and hydrogeological investigations were carried out for the study. Ten Vertical Electrical Soundings (VES) of the Schlumberger array was used to investigate the properties of the subsurface lithologies to determine their properties especially, clay, for siting a landfill. Clay, an attenuating material, is significant for siting a landfill facility because it tends to isolate potentially toxic wastes from the environment by slowing down the movement of leachates into groundwater and the environmental. Quantitative interpretation of data of the VES survey using the IPI2win computer software revealed the presence of four to five geologic layers comprising of sandy top soil (247 – 1964Ωm), silty sand (98 – 3488Ωm), clayey-shally/sand (68 – 3922Ωm), saturated clayey sand (31 – 3226Ωm) and loose sand (478Ωm). Clay was found to be abundant in the area and found at depths ranging from 30m to infinity. Geologically, structures like lineaments abound and were analysed; they show a dominant trend in the NW – SE direction from the Rosette Diagram. Lineaments are useful for studies because they are possible conduits where decomposed wastes in liquid form, such as leachates, get transported to pollute groundwater. Hydrogeological studies surveyed Static Water Levels (SWL) measurement from 51 hand dug wells in the study area. The SWL ranges between 5.8m and 37.1m. The data from the SWL was used to construct the absolute water level map in a 3D form to show the flow direction of the groundwater. The study revealed the presence of impermeable clays at VES 1, 2, 3, 9 and 10. This is significant for selection for landfill due to its pollution-prevention properties of groundwater pollution. The investigations carried out in this study show that Shabu, a town located about 8km from Lafia, is likely suitable for siting a landfill facility; because of the abundance of clay at a shallow depth of 30m and with limited preponderance of lineaments.
Highlights
Since emphasis is placed on clay as key to siting a landfill, some of the Vertical Electrical Soundings (VES) stations such as VES 1, 2, 3, 9 and 10 revealed from the survey, to have abundant clay (Table 1)
Clay present in VES 1 has resistivity value of 31 Ωm and a depth at infinity; at VES 2, the resistivity of clay is 21 Ωm and it lies at infinity depth; at VES 3 clay was found to be at infinity depth but has a resistivity value of 23 Ωm; clay layer found at VES 9 has a resistivity value of 58 Ωm at infinity depth; clay found at VES 10 located at Shabu, has a resistivity value of 98 Ωm and slightly buried at a shallow depth of 25.5 m
The preliminary investigations of this study, which involve geo-resistivity data collection, geological and static water level from Hand dug well (HDW), were integrated and used to delineate Lafia and environs for the purpose of suitably siting a landfill to curb the indiscriminate disposal of Municipal Solid Waste (MSW)
Summary
Especially in a developing country like Nigeria, is a challenge that is ravaging and affecting the environment adversely. Solid Waste (MSW), comes in different forms which comprise of mixed metals, kitchen waste, paper, food scraps, plastics and glass [1]. Namo Micah Musa et al.: Preliminary Investigations for Landfill Siting in Lafia, Nasarawa State of Central Nigeria municipality officials, public health officials, civil engineers and engineering geologists in their quest to safeguard the environment. The construction and operation of an engineered sanitary landfill ensures proper and adequate waste management by disposing MSW in a way that safeguards the environment by laying the wastes in thin layers and subsequently compressing them into smaller volumes possibly by covering them with compacted soil after each working day. Landfills in years to come will become the major mode of waste disposal because cheap equipment and machines are required to operate them
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