Integrated approach to unsaturated zone characterization as it relates to burial practices and its impact on the immediate environment

Abstract

Improper sitting positioning of cemeteries in Nigeria is mostly responsible for groundwater pollution. Poor water quality may lead to some communicable diseases in most rural and urban areas of the southwestern part of Nigeria. The environmental impact of cemeteries close to residential areas within the Edunabon metropolis, southwestern part of Nigeria, was assessed. The research is aimed to understand the impact (if any) of the cemetery on the quality of water and soil within the vicinity and to investigate the suitability of soil materials underlying the cemetery as a special lining material. An integrated approach using geotechnical characterization, vertical electrical sounding and groundwater quality assessment was used in the present study. The geotechnical test involved six bulk undisturbed soil samples taken from two borrow pits within the cemetery. Index property tests (grain size distribution, specific gravity, natural moisture content, and Atterberg limits), engineering property tests (compaction test), X-ray diffraction, and X-ray fluorescence tests were carried out on the soil samples with their porosities and permeability estimated according to BS 1377. The majority of the study area is a wetland with a topography that descends into a gaining stream around 10 m from the cemetery. The soil of the cemetery is made up of coarse-grained porous lateritic soil, clay, and silt (0.22–3.88 percent), with a significant amount of gravel/sand (73.50–83.96 percent). Except in the control well, water analysis revealed a high total coliform concentration of 14–89 and a total hardness of 86–380 mg/L. When compared to the World Health Organization (WHO) drinking water standard and the Nigerian drinking water standard, the majority of cation concentrations were greater than the safe limits. The depth to contamination correlates to the depth of the aquifer in the research region, according to the results of electrical resistivity. Because of the narrow unsaturated zone, the study found that the position of the cemetery has a high risk of environmental impact on its near vicinity.