Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

Elijah A. Ayolabi ¹

Affiliations
1 Department of Physics, University of Lagos, Lagos, NG

Abstract

Vertical electrical sounding consisting of three Wenner array and thirteen schlumberger array has been carried out at the premises of Alagbaka primary school, Ahure Southwest Nigeria. The aquiferous unit in the area is composed of weathered and fractured rocks whose resistivity ranges from 26 to 366 Ωm and thickness of 2 4 to 29 3 m. The isopach shows that the overburden thickens towards the east and is thinnest towards the south. The geological map derived from the coefficient of anisotropy of the underlying rocks shows this the Eastern end undelain by migmatities have coefficient of anisotropy ranging between 1 5 and 2 5 while the southwest, west and northwest side is underlain by chanockites of high (3 - 7 4) coefficient of anisotropy. The eartern end offers a good prospect for groundwater exploration.

Keywords

Groundwater, Geoelectical Study, Anisotropy, Akure, Southwest Nigeria.

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Elijah A. Ayolabi ¹

Affiliations
1 Department of Physics, University of Lagos, Lagos, NG

Abstract

Geoelectric resistivity technique of geophysical investigation have been used to evaluate the effect of leachate generated from Olushosun landfill on the groundwater in the area. The result shows that the first aquifer has been greatly polluted by the leachate generated from the decomposed heap of refuse materials at the landfill site. A total depth of up to 73 m has been delineated as polluted area with resistivity ranging from 16 to 361 Ωm as compared to resistivity values ranging between 2167-3714 Ωm for the unpolluted area. The results of the evaluation of the protective capacity of the overburden material within the unpolluted zone shows that the overburden material has a weak protective capacity and this may have largely been responsible for the high level of pollution observed in this area.

Keywords

Leachate, Pollution, Landfill, Geoelectric Study, Southwest Nigeria.

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Elijah A. Ayolabi ¹, Folashade J. Oyelayo ¹

Affiliations
1 Geophysics Program, Department of Physics, University of Lagos, Lagos, NG

Abstract

The impact of the buried refuse at the abandoned Achakpo refuse dumpsite in Ajeromi-Ifelodun Local Government area of Lagos State on the groundwater has been carried out using geophysical and hydrochemical methods. The geophysical method involved vertical electrical soundings while the hydrochemical analysis carried out on the samples of groundwater from four hand dug wells in the vicinity of refuse dumpsite and one sample of surface water. Three geoelectric layers were delineated from the interpretation of vertical electrical sounding data and the map of the depth to the top of resistive bed was produced to show the extent of pollution. Supporting evidence was provided by the hydrochemical analysis of samples from groundwater and surface water which show very high value of conductivity, total dissolved solids, total suspended solids, Alkalinity, Total hardness, ca²⁺, Fe²⁺and PO₄^3-.

Keywords

Refuse Dumpsite, Vertical Electrical Sounding, Hydrochemical Pollution, Lagos, Nigeria.

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