COMPARATIVE ANALYSIS OF THE EFFECT OF CLOSED AND OPERATIONAL LANDFILLS ON GROUNDWATER QUALITY IN SOLOUS, LAGOS NIGERIA

Waste is discarded materials of no further use to the owners and the pattern of its generation is a function of the level of urbanization, industrialization and economic status of society. The most convenient strategy of solid waste disposal is landfill which is usually sited in abandoned excavated site. The quality of the groundwater which is the major source of potable water are affected by the waste disposal site. The objective of this work is to examine the impact of solid waste disposal site on the ground water quality of the residential areas boundary the site. For empirical and experimental examination of the concentration of contaminant in the groundwater of the studied area, fifteen wells were sampled and three (3) leachates for laboratory analysis. The results were analyzed with standard statistical package and compared with WHO, 2004 and NSDWQ, 2007 standard. The statistic correlation analysis indicated that pH of the water has close relationship with many heavy metals and physicochemical parameters. In other to verify the actual concentration of the examined variable, correlated parameter in heavy metals were subjected to regression model. Spatial variations between closed and operational landfills were compared. Therefore, concentration of some parameters like heavy metals diminished with time as a result of the analysis of the sampled around closed landfill and many parameters reduced with distance while other increased. Closed landfill has the capability of generating certain pollutants than existing landfill; conversely some pollutants can also be highly generated in operational landfill than the former. In conclusion, groundwater contamination is the function of time, types of waste, topography, soil, underlying geology, surface water ingression and direction of groundwater flow. The research recommends appropriate material to cap the closed site and treatment after disposal.