Vulnerability assessment of groundwater pollution in the vicinity of an active dumpsite (Olusosun), Lagos, Nigeria
The deleterious impacts of dumpsite activities and the associated risk on both theenvironment and human is consequential, hence this study assessedgroundwater vulnerability to pollution from dumpsite using a modified DRASTICmodel. Six hydrogeological factors: D- Depth to water, R- Net Recharge, AAquifermedia, L- Distance of well to dumpsite, T- Topography, and C- Claycontent were used in the modification (DRALTC) based on peculiarity of thestudy area. Cluster analysis of groundwater data and Water Quality Index (WQI)were also evaluated. The groundwater vulnerability index was characterized bytwo zones; forty five percent (45%) moderate and fifty five percent (55%) highzones. The dendogram showed three clusters of chemical dissimilarities. TheWQI showed values between 61.8 and 205, indicating good, poor and very poorclass of water. The analysis of the groundwater samples showed nitrateconcentration ranging from 7.60 to 35.6 mg/L and from 8.56 to 32.4 mg/L in dryand rainy seasons, respectively. The DRALTC model was validated using nitrateconcentration. Though, there appeared relative groundwater protection fromcontamination, there is still need for measures to mitigate further contaminationand associated risk in the moderate vulnerability zones. DRALTC model is proveda good tool in groundwater management.