Detection and Delineation of Contaminant Migration using the Terrain Conductivity Technique outside the Perimeters of the Dompoase Landfill Facility in Kumasi – Ghana.

Electromagnetic conductivity survey was conducted outside the perimeters of an active municipal landfill facility located at Dompase, a suburb of Kumasi, Ghana. The study was undertaken to identify potential conductive layers probably connected with leachate communication from the landfill. The Geonics EM 34-3 terrain conductivity equipment was used as the geophysical tool for the survey. Operating in the low induction number regime, three intercoil separations of 10, 20 and 40 m were used in both the horizontal and vertical dipole configurations. The specific area of interest was the two sides of a discharge stream which carries treated effluent from the treatment ponds. Data were acquired at 10 m meter interval along sixteen east–west profiles, each of length 100 m, running approximately perpendicular to the discharge stream. There were seven and nine profiles respectively on the right and left sides of the discharge stream. The high conductivity found within the depths 30 to 60 m close to the southern boundary of the landfill might suggest leachate communication from the landfill. The linear pattern of the contour lines in that anomalous zone probably indicate the presence of zones of weakness trending approximately perpendicular to the direction of flow of the discharge stream. This weak zone could account for the lateral spread of leachate within those depths, where leachate plume has so far migrated. Keywords: Aquifer, Contamination, Leachate, Electromagnetic conductivity, Geonics EM-34-3, Horizontal dipole, Landfill, Monitoring well, Vertical dipole

Electrical Resistivity And Induced Polarization Imaging For Refuse Dump Site

Contamination from landfills as a result of leaching from organic and inorganic waste poses a threat to the environment because, subsoil and groundwater are affected. The contamination is more serious in developing countries where waste management is inefficient. The aim of this study was to determine the extent of pollution at this site. Three profiles were surveyed: two in North-South direction and the third in Northeast-Southwest. 2D electrical resistivity and Time Domain Induced Polarization (TDIP) data sets have been acquired along the three profiles in Boadi Community. Electrical resistivity and induced polarization together with excavations were successful in mapping the extent of the leachate plume. The study demarcated clearly three main zones: the first, second and third zones indicated chargeabilities > 12.8 msec near the surface, > 6.4 msec and > 12.8 msec at the base respectively. Similarly, resistivities < 12 Ωm, 12 to 24 Ωm and >192 Ωm for the first, second and third zones respectively were delineated. The relatively lower electrical resistivity areas were thought to be due to the presence of the leachate plume and the comparatively higher chargeability zones were interpreted as duricrust. The relatively lower chargeability represents absence of polarizable materials. The study also delineated the weathered basement granodiorites showing relatively higher resistivities. These TDIP and ERT results show that the methods have been successful in mapping the landfill leachate plume. The results from the resistivity and chargeability compare very well with the excavations