Publisher: Bachudo Science Co. Ltd

Electrical Resistivity Soundings To Determine Subsurface Contamination In The Vicinity of Refuse Dump

B. S. Badmus, E. A. Ojelabi, T. Oyedele
KEYWORDS: Resistivity, groundwater, leachate-saturated, contamination, layer


Four Wenner apparent pseudosections and a vertjcal electrical sounding were made at the Orita Apedn refuse dump site, Ibadan, South West Nigeria, to map the gross layered structure of the refuse as well as the extent of groundwater contamination. Wood, leaves, newspaper, cloth, polythene bags, plastics, glass and metal refuse interspersed with soil exhibited resistivity of 11.6 ohm-m and layer tllickness of 0. 7m as obtained from the inversion of the sounding. The unsaturated layer has a resistivity of 6.8 ohm-m and thickness of0.6in while 1eachate-saturated is characterised by low resistivity of 2.9 ohm-m; L2 m tl1ickness. The fractured saturated layer exhibited resistivity of 49.6· ohm-m. The accurate determination of the reftlse thickness in geoelectrical model is primarily due to a strong· resistivity contrast between the leachate saturated (2.9 ohm-m) and underlying saturated fractured rock (49.6 ohm-m). Despite this contrast, models generated from electrical resistivity soundings are reasonably accurate in their depictions of internal structure of the dump site. The hydrochemical analysis of the surface and groundwater samples collected within the vicinity of the dtiinp site were analysed for physico-chemical parameters .. The results produced higher concentration of TDS, total hardness, Cf, N03., Mg2+, Na+, K+ ru1d pH value fur water collected at close locations to the dump site than those far away from the site:an evidence for a quantitative assessment of groundwater contamination.

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