Determination of Potential Landfill Site in Tarkwa Area Using Multi-Criteria GIS, Geophysical and Geotechnical Evaluation

Asare Asante-Annor,Ebenezer Ansah,Samuel Asare Konadu

doi:10.4236/gep.2018.610001

Abstract

A 24-acre land at Aboso serves as the site where municipal solid waste from Tarkwa and its environs are openly dumped. Evaluation of the suitability of this existing landfill site for the construction of an engineered landfill was determined. Reconnaissance survey, structural mapping, determination of depth to groundwater, geotechnical site investigation as well as socio-economic indicators showed that the existing landfill site is not suitable for an engineered landfill construction. A multi-criteria GIS model was used to select an alternative suitable area for the construction of an engineered landfill. The multicriteria GIS modelling identified fourteen (14) suitable areas for the siting of landfill in the Tarkwa area. A site located in Domeabra was chosen due to its proximity to the neighbouring communities of Tarkwa, Nsuta and Aboso. The suitability of the proposed site in Domeabra was assessed using geotechnical and geophysical methods. The geotechnical methods included the testing of soil properties such as moisture content, particle size distribution, Atterberg limit, bulk density, specific gravity, and compactibility. The soils at Domeabra site are predominantly gravel and sand, well graded with gradual increase in clay content with depth and good moisture content (less than 30%). The gravel and sandy soils have good to excellent shear strength and work ability. The soils in Domeabra have suitable dry density (1.3 - 2.1 Mg/m3), bulk density (1.7 - 2.5 Mg/m3) and specific gravity (2.2 - 2.9) for landfill construction. The geophysical method involved the use of seismic refraction tomography. The geophysical survey showed that the site is made up of four layers namely the top soil (0.5 - 2 m), weathered material (5 - 15 m), saturated material (10 - 15 m) and fresh rock. The water table occurs at a depth of 12 to 15 m. The proposed area in Domeabra based on the geophysical and geotechnical investigations is suitable for the construction of engineered landfill.

Highlights

Waste generation is on the ascendancy in both developing and developed countries
Reconnaissance survey, structural mapping, determination of depth to groundwater, geotechnical site investigation as well as socio-economic indicators showed that the existing landfill site is not suitable for an engineered landfill construction
The model depicts a velocity distribution that generally increases with depth

Summary

Introduction

With increase in the global population and the rising demand for food and other essentials, there has been a rise in the amount of waste being generated daily by each household [1]. The huge waste generated has necessitated the siting and construction of engineered landfill sites where municipal solid waste (MSW) are dumped. MSW consists of daily items including recyclable materials like paper, plastics, textiles, metals, glass, yard wastes; organic materials like food; inorganic materials such as dirt, a small amount of construction wastes; and miscellaneous other materials [2]. Uncontrolled dumping of wastes at the outskirts of towns and cities has created overflowing landfills, which have environmental impacts in the form of pollution to soil, groundwater, air, and contribute to global warming [7]. Several studies conducted to examine the health and environmental effects arising from waste dumps showed that a link exists between the two [8] [9] [10] [11] [12]

Results

Discussion

Conclusion