Application of multivariate and geospatial techniques to assess groundwater quality of two major dumpsites in Sierra Leone

Abstract

Globally, groundwater in landfill environments faces unique contamination challenges. In Africa, these problems are exacerbated as a number of landfills are not properly engineered to curtail the percolation of leachates. In Freetown specifically, the dumpsites do not contain liners hence leachate leaks, mixes with discharges of raw sewage and trigger the spread of infectious water-borne diseases. This study sought to assess the extent of groundwater quality and pollution source apportionment within the Granvillebrook and Kingtom dumpsites. The results of the physicochemical analysis showed that wells within the two dumpsites measured a high amount of flouride, bicarbonate and nitrate suggesting anthropogenic input. The high pH, electrical conductivity, and bicarbonate concentrations in some of the groundwater at the Granvillebrook dumpsite indicate denitrification and leachate pollution. The piper plot showed that the groundwaters in the Granvillebrook dumpsite demonstrated magnesium bicarbonate, sodium bicarbonate,and mixed water types. This study also finds that all the groundwaters at the Kingtom dumpsite (during the dry season) were mixed water types which gradually decrease into magnesium bicarboante water type in the wet season due to water-rock interaction. On the basis of water quality indexes, the WQI and OIP results established that 41.7 and 16.6% of the groundwaters at the Granvillebrook dumpsites were unsuitable for human consumption. Groundwaters at the Kingtom dumpsite (except well KW46) were acceptable for consumption. The principal component analysis showed that pollution resulting from dumpsite leachates, sewage discharge, hog manure, anthropogenic flouride, urine-contaminated wastewater, and atmospheric sulfate caused by the combustion of fossil fuels were the possible pollution sources in the study areas. Contrary to other previous studies, this research provides new information on water quality indexes and spatial distribution of physicochemical parameters in the groundwaters of the Granvillebrook and Kingtom dumpsites.