SOURCE:

Faculty: Physical Sciences
Department: Physics And Industrial Physics

CONTRIBUTORS:

Ikhifa, I.
Umego, M. N.
Obiekezie, T. N

ABSTRACT:

Integrated geophysical techniques have been used to determine the soil and groundwater contamination at three uncontrolled dumpsites in Benin City. Qualitative assessment of the area was carried out using very low frequency (VLF) electromagnetic and electrical resistivity tomography (ERT) methods, to determine the degree of contamination at the sites. The field survey was carried out using Dipole-dipole arrays with a spread of 84m-164m at Ovia North East Local Government Area (Oluku and Capitol dumpsites), and Ikpoba Okhia Local Government Area (Ikhueniro dumpsite) in Benin City, Edo State. A total of 30 VLF-EM profiles were conducted with length of 150m-350m at the three dumpsites. The approximate topography of the dumpsites was obtained using global positioning system to determine the surface run-off direction. The electrical resistivity tomography method was projected to produce 2D and 3D view of the sites. Both ERT and VLF methods revealed persistent low resistivity (1-20Ωm) of leachate to the depth of 39.4m. With the aid of these tomograms, two distinct conductive zones had been mapped and identified with an intermediate resistivity layers within the study sites. They are: highly conductive leachate contaminant plumes seeping from surface points to the aquifer; and highly resistive zones. Based on the geophysical results in the study areas, boreholes should be sited and drilled beyond 40m in the study locations to minimize groundwater contamination by the dumpsites.