Mapping of Aquifer Contamination Using Geoelectric Methods at a Municipal Solid Waste Disposal site in Warri, Southern Nigeria

Abstract

Vertical electrical sounding, 2-D resistivity imaging and hydrogeochemical analysis have been applied in the study of aquifer contamination in a municipal solid waste disposal site in Warri, southern Nigeria. Fourteen sounding points were occupied in the area and the resistivity imaging employing the Dipole dipole configuration was measured along two orthogonal traverse lines cutting across the dumpsite. The geoelectric sections reveal four distinct layers namely topsoil, fine sand, medium grained sand and fine to medium grained sand. The low resistivity values obtained beneath the dumpsite in the southern direction in the N-S geoelectric section, could be attributed to the effect of leachate from the dumpsite. The results of the resistivity imaging show contamination in the W-E and N-S direction, with values ranging from 22 to 100 ohm- m, because the area show low longitudinal conductance of < 0.05 mhos and 0.06 to 0.09 mhos, which depicts weak and low protective capacity respectively. Finally, the results of the hydrogeochemical analysis confirm the concentration of lead and total viable bacteria counts and this is an indication that the aquifer is gradually receiving contamination from the dumpsite.