TITLE:
Determination of Potential Landfill Site in Tarkwa Area Using Multi-Criteria GIS, Geophysical and Geotechnical Evaluation
AUTHORS:
Asare Asante-Annor, Samuel Asare Konadu, Ebenezer Ansah
KEYWORDS:
Landfill Site, Multi-Criteria GIS, Seismic Refraction Tomography, Geotechnical Site Investigation, Tarkwa Area
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.6 No.10,
September
30,
2018
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.