Subsurface Imaging of Leachate Plume in Some Communities of Esan North East Local Government Area, Edo State, Nigeria

Groundwater being one of the most valuable drinking water resources is often fresh and cold, since it is filtered through the ground, it is often fresh and cold and usually cleaner than surface water. Unfortunately, the over dependence on groundwater came as a result of lack of pipe borne water. Portable water does not contain chemical substances or microorganisms which could cause hazards to health. However, the quality of groundwater is under intense stress form increasing demand and withdrawer, climate change and anthropogenic activities and this demands consideration because the people of the study area have no means of judging the quality and safety of water themselves.

To image the subsurface in the area, the Wenner-Schlumberger array method utilizing the Petrozenith resistivity metre was employed to delineate leachate plume. The global positioning system device was used to obtain the geographic co-ordinate (longitude and latitude) and altitude in metres of beginning and ending of survey lines. The ZondRes2D and Surfer 11 software were used for the interpretation of data. Groundwater samples were collected in Eguare (January 2013 and December 2014) and Unuwazi (January 2013) and subjected to physical and chemical analysis after which was compared using World Health Organisation (W.H.O) drinking water benchmark.

The result from the laboratory analysis revealed evidence of pollution from physical and chemical sources in Eguare and Unuwazi of Esan North East Local Government Area, Uromi, Edo State. The hand dug well in Unuwazi was not functioning as at time of survey in December 2014 and therefore water sample was not taken. The geoelectric survey delineated leachate plume in Eguare which corroborates with the result of laboratory analysis of groundwater sample taken from the survey location. However, Unuwazi inferred to be clay, lateritic clay and laterite revealed absence of resistivity anomaly due to few numbers of resistivity values within the defining range of (1.5-20) Ωm and (6.5-20) Ωm