Time-domain spectral induced polarization and magnetics for mapping municipal solid waste deposits in Ghana

Environmental pollution from solid waste landfilling is a serious risk for groundwater and downstream surface water, especially when landfilling is carried out unengineered, with no protective layer underneath the waste deposits. Most research in Ghana and in other developing countries on unengineered landfills depend almost exclusively on hydrochemical and geochemical analysis, which is not necessarily representative of the entire dumpsite catchment area. For this reason, integrated and cost effective geophysical methods, namely DC electrical resistivity, full waveform time-domain induced polarization and ground based magnetic measurements were employed to map and characterize four dumpsites in the Kumasi Metropolis, the seconds most populated city in Ghana. The results of one site, namely the decommissioned Ohwim waste dumpsite, are presented. The magnetic surveys helped in the mapping of the lateral extent of the waste deposit. The DC /full wave induced polarization tomography on the other hand mapped the vertical extent of the dumpsite and characterized the hosting geology. Furthermore, some regions were identified, where a pollution plume is likely to be present.