The Application of Geophysical Techniques in Tracking Leachate Plumes Migration in a Typical Cemetery within the Sandy formation in Benin City, Nigeria

The survey aim is to track leachate plumes within the sandy formationwhich is below the surface laterite layer. It investigates the presence andmigration of leachate plumes in the sandy region in a typical cemetery(Third Cemetery), in Benin City, Nigeria. The research engaged VerticalElectrical Sounding (VES), 2-Dimensional computation of migrationin both the vertical and horizontal directions. The electrical resistivitydata collected in parallel equidistant lines was processed to obtain geoelectric models using Res2dinv. The leachate plumes in the cemeterymigrate vertically and horizontally at different rates. The maximum andminimum rates of vertical migration are 4.1 and 0.2 cm/day respectively,while the maximum and minimum rates of horizontal migration are 32.8and 1.7 cm/day respectively. Volumetric analysis of the plume zonesindicates that of the 75,231m3 of the subsurface imaged, 6,322 m3 is thezone contaminated by leachate plume, that is, 8.4 % of the earth volumeinvestigated contained leachate plume. The research also showed thatrepeated ERT surveys can track movement of leachate plume emanatingfrom decomposed dead bodies over time in active cemetery. The averagetravel time for a leachate plume to transverse a vertical distance of 6.6 min coarse sand is 366.7 days at constant migration speed of 1.8 cm/day.