Investigating the Effect of Leaching from an Active Landfill on Groundwater Quality Using Geophysical and Geochemical Approach in Abeokuta, Southwestern Nigeria

Abstract

Investigation of groundwater contamination from an active landfill was carried out in Saje, Abeokuta Ogun state, Nigeria using geophysical and geochemical methods. Four resistivity traverses picked up within the landfill. Wenner array electrode configuration was adopted and the data were interpreted using RES2DINV program. Quantitative valuations were accomplished by geochemical and hydrogeochemical facies of groundwater samples collected from ten dug wells in the arcade of Saje landfill. Fifteen parameters were analysed in the groundwater samples. The results of the 2D resistivity analysis showed that there is a constant and progressive increase in the depth of migration of the contaminants generated from this landfill site into the subsurface environment as its ages. The results of both physical and chemical parameters of the water analysis revealed that all the parameters were 100% in compliance with the World Health Organization (WHO) and Nigerian Standard of Drinking Water Quality (NSDWQ) standard permissible limits for drinking, water except for pH (90%), Calcium (80%) and Lead (80%). The classification of water samples of the study area using Piper Trilinear diagram revealed that 70% of the analysed water samples are of CaHCO3 (fresh water) type, 20% are of CaCl2 type and 10% are CaMgCl type. The calculated values of irrigation parameters such as; Magnesium Absorption Ratio, Sodium Absorption Ratio, Total dissolve solid, Soluble Sodium Percentage, Kelly's Ratio and Permeability Index for most of the groundwater samples were found to be suitable for irrigation. The groundwater quality index evaluation acquired for the study area ranges from 3.8 – 18.1. This study established that the groundwater around this region is 100% suitable for drinking purposes.