Groundwater Contaminants Investigation in a Basement Area of Nigeria Using 2D Electrical Surveying Methods

Abstract

Some of the common methods of monitoring and mapping groundwater contaminants is by extracting and analyzing samples of the groundwater obtained from wells within the expected investigation area, although lots of limitations are encountered in this type of investigation technique (point wise method) due to the nature of most subsurface layers, which are heterogeneous and anisotropic in nature and acquiring information using this method is comparatively difficult due to the few points acquired for investigation. Common and most recent method used to overcome such type of limitation and improve ground monitoring cost-effectively, is the use of Direct Current Resistivity measurements. This method gives a comprehensive characterization of the electrical properties of the subsurface layers (volume) needed. This paper investigates the usability and advantages of the resistivity method as a better method technique in monitoring groundwater contaminants in basement area or terrains under different seasons, in monitoring programmes. The work comprises field investigations at several sanitary landfills around the basement area of Ado-Odo town, in Ogun State, Nigeria, using Wenner array configuration (tomography) technique. From the results obtained, the level/degree of contaminants are easily identified and evaluated within the subsurface layers. We therefore concluded that the use of resistivity survey method gives an improved, better and appropriate information, generally suitable for mapping and monitoring of conductive groundwater contaminants in basement area.