Vulnerability Assessment of Water in Landfill Site and Environs: A Case Study of Olusosun in Lagos, Nigeria

Makinde E. O., Paul T. E.*, Olatunbosun O. E. and Nwilo P. C.

Department of Surveying and Geoinformatics, University of Lagos, Akoka, Lagos state, Nigeria

*Corresponding Author: temmanuel565@gmail.com

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Vol. 4 No. 2 | October 2020 | Pages 214 – 225

https://doi.org/10.36263/nijest.2020.02.0165

Abstract

ABSTRACT

This study assessed the vulnerability of landfill site in Olusosun, Lagos Nigeria using modified DRASTIC (DRASTIC L) model in a geographical information system environment. It also analyzed water samples with a view to determining the amount of trace metals concentrate present. Water samples were collected from different Boreholes and Wells with a radius of 500m to the landfill site. The modified DRASTIC (DRASTIC L) based on eight parameters such as Depth to water, Net recharge, Aquifer media, Soil media, Topography, Impact of vadose zone, Hydraulic conductivity and Distance to landfill site. The vulnerability index was calculated using a sum overlay of the eight parameters. ArcGIS 10.2 software was used to integrate all these parameters together to obtain Boreholes and Wells vulnerable zones I areas. The results showed that out of a total of 228.38 hectares, only about 47.46 hectare was observed to be within the low vulnerable zone having a DRASTIC index range between 113 – 136; while about 130.65 hectares were found to be in the moderately vulnerable zone with a DRASTIC index ranging between 136 and 144. About 50.28 hectares were within the high vulnerability zone having a DRASTIC index range between 144 and 163.Atomic Absorption Spectroscopy (AAS) was used for to test the concentrations of the heavy metals in the water samples collected and found that aside the presence of other heavy metals, Chromium was found to be present in most Wells and Boreholes measuring between 0.08 mg/L and 0.43 mg/L which is above the World Health Organization Standard of 0.05 mg/L for drinking water. This study concluded that the groundwater is contaminated and the level of pollution is directly related to the distance from the landfill.

Keywords: Landfill, contamination, Pollution, GIS, Vulnerability, Environment