Pollution vulnerability and health risk assessment of groundwater around an engineering landfill in Lagos, Nigeria

Solid wastes disposal, through the use of non-sanitary landfill facility has tremendous health impacts on man and environment, yet without regard to environmental consequences, the use of controlled dumpsite is at best a common practice in underdeveloped countries. The paucity of data on modelling of potential vulnerability of neighboring aquifer to the pollution from Soluos dumpsite (a non-engineering landfill) necessitate the study of the use of a model DRALTC (modified DRASTIC) on the estimation of vulnerability of groundwater to dumpsite pollution and associated health risks. Six hydrogeological factors: Depth to water, net recharge, aquifer media, distance of wells to dumpsite, topography, and clay content, were involved in the modification of the model (DRALTC) which helps in characterizing the hydrogeological setting of the study area and estimation aquifer vulnerability. Sodium adsorption ratio (SAR) and permeability index (PI) were used to analyse the data generated in this study. The health risk indices (HRI) were also estimated for trace metals in the groundwater samples. The pollution vulnerability ranged between (161 and 175) moderate and high groundwater pollution potential. SAR results observed in this study reveal 25% excellent, 20 % good, 10% doubtful and 45% unsuitable. The order HRI observed was Cd > Zn > Cu > Ni > Pb for adult, while Cd > Cu > Ni > Zn >Pb trend was found for children, though the HRI value for all the metals investigated were within the safe limit (HRI < 1.0) suggesting no health risk.