2D resistivity tomography was used in , , and directions to delineate the extent of leachate plumes around a solid waste landfill in Ikare Akoko, Ondo State, behind the secretariat. I access the geometry and depth contamination extent of the landfill repository using dipole-dipole method and Global positioning system to ascertain the image of the subsurface and the position at the earth surface. The study area is underlain by Precambrian basement rocks. Quantitative interpretation of pseudosection results shows that in traverse 1, stations 7, 8, and 9 form a conductive path at the depth of 1–10？m and penetrate to depth of 25？m; the second traverse shows a layer of highly conductive structure extending diagonally across the study area, while the third traverse is partly conductive and largely resistive due to its closeness to fresh basement rocks. The 2D structure has shown various conductive path ways via fractures and openings, thus, contaminating the groundwater. I recommend that further geochemical analysis of the water should be done to ascertain the level of contamination. 1. Introduction Recent studies have shown that the problem of environmental contamination and waste management is one of the main concerns of geoscientists and researchers from other related fields of science around the globe. Fast industrial development and the uncontrolled growth of the urban population result in the production of toxic solid wastes. Urban waste materials, mainly domestic garbage, are usually disposed of inadequately in waste disposal sites posing a high risk to the underground water resources, the environmental pollution, and the community health. Moreover, older waste sites often lack reliable geological or artificial barriers, so that leaching of pollutants into the groundwater is a concern. Contamination problems are particularly severe for waste dumped in abandoned gravel pits, many of which extend to below the groundwater table. Being small and unregulated, the exact location, structure, and contents of such landfills are either unknown or poorly documented. The solution to the day-to-day problems of modern urban societies demands fast and effective geophysical methods. One of the most frequent demands in metropolitan areas is to determine the landfill’s geological and geotechnical structure shape and extend, together with the excavation and dumping history [1–3]. Details on the contents of a landfill may be difficult to acquire but are essential for evaluating the level of risk associated with leaking pollutants. In such context, the integrated use of
References
[1]
A. R. Allen, A. Dillon, and M. O'Brien, “Approaches to landfill site selection in Ireland,” in Engineering Geology and the Environment, P. G. Marinos, G. C. Koukis, G. C. Tsiambaos, and G. C. Stournaras, Eds., pp. 1569–1574, Rotterdam, The Netherlands, 1997.
[2]
J. D. Mather, “Preventing groundwater pollution from landfilled waste-is engineered containment an acceptable solution?” in Groundwater Quality, H. Nash and G. J. H. McCall, Eds., pp. 191–195, Chapman & Hall, London, UK, 1995.
[3]
I. Georgaki, P. Soupios, N. Sakkas et al., “Evaluating the use of electrical resistivity imaging technique for improving CH4 and CO2 emission rate estimations in landfills,” Science of the Total Environment, vol. 389, no. 2-3, pp. 522–531, 2008.
[4]
A. Green, E. Lanz, H. Maurer, and D. Boerner, “Template for geophysical investigations of small landfills,” Leading Edge, vol. 18, no. 2, pp. 248–254, 1999.
[5]
K. H. Heitfeld and M. Heitfeld, “Sitting and planning of waste disposal facilities in difficult hydrogeological conditions,” in Engineering Geology and the Environment., P. G. Marinos, G. C. Koukis, G. C. Tsiambaos, and G. C. Stournaras, Eds., pp. 1623–1628, Rotterdam, The Netherlands, 1997.
[6]
E. Lanz, L. Jemmi, R. Muller, A. Green, A. Pugin, and P. Huggenberger, “Integrated studies of Swiss waste disposal sites: results from georadar and other geophysical surveys,” in Proceedings of the 5th International Conference on Ground Penetrating Radar (GPR '94), pp. 1261–1274, 1994.
[7]
L. Orlando and E. Marchesi, “Georadar as a tool to identify and characterise solid waste dump deposits,” Journal of Applied Geophysics, vol. 48, no. 3, pp. 163–174, 2001.
[8]
V. Saltas, F. Vallianatos, P. Soupios, J. P. Makris, and D. Triantis, “Application of dielectric spectroscopy to the detection of contamination in sandstone,” in Proceedings of the International Workshop in Geoenvironment and Geotechnics, pp. 269–274, Milos Island, Greece, September 2005.
[9]
C. Bernstone, T. Dahlin, T. Ohlsson, and W. Hogland, “DC-resistivity mapping of internal landfill structures: two pre-excavation surveys,” Environmental Geology, vol. 39, no. 3-4, pp. 360–371, 2000.
[10]
E. Aristodemou and A. Thomas-Betts, “DC resistivity and induced polarisation investigations at a waste disposal site and its environments,” Journal of Applied Geophysics, vol. 44, no. 2-3, pp. 275–302, 2000.
[11]
C. B. Dawson, J. W. Lane Jr., E. A. White, and M. Belaval, “Integrated geophysical characterization of the Winthrop landfill southern flow path, Winthrop, Maine,” in Proceedings of the Smposium on the Application of Geophysics to Engineering and Environmental Problems, p. 22, Environmental and Engineering Geophysical Society, Las Vegas, Nev, USA, February 2002.
[12]
L. Bengtsson, D. Bendz, W. Hogland, H. Rosqvist, and M. Akesson, “Water balance for landfills of different age,” Journal of Hydrology, vol. 158, no. 3-4, pp. 203–217, 1994.
[13]
G. Trochobanogous, H. Theisen, and S. Vigil, Integrated Solid Waste Management, McGraw Hill, New York, NY, USA, 1993.
[14]
S. O. Ojo, “Factor productivity in maize production in Ondo state Nigeria,” Applied Tropical Agriculture, vol. 15, pp. 57–65, 2000.
[15]
M. H. Loke, I. Acworth, and T. Darlin, “A comparison of smooth and blocky inversion methods in 2D electrical imaging surveys:,” Geophysics, vol. 35, pp. 266–271, 2003.
[16]
C. Pomposiello, C. Dape？a, A. Favetto, and P. Boujon, “Application of geophysical methods to waste disposal studies,” in Municipal and Industrial Waste Disposal, X.-Y. Yu, Ed., 2012.
[17]
C. Degroot-Hedlin and S. Constable, “Occam's inversion to generate smooth, two-dimensional models from magnetotelluric data,” Geophysics, vol. 55, no. 12, pp. 1613–1624, 1990.
[18]
M. H. Loke and R. D. Barker, “Least-squares deconvolution of apparent resistivity pseudosections,” Geophysics, vol. 60, no. 6, pp. 1682–1690, 1995.
[19]
M. H. Loke and R. D. Barker, “Rapid least-squares inversion of apparent resistivity pseudosections by a quasi-Newton method,” Geophysical Prospecting, vol. 44, no. 1, pp. 131–152, 1996.
[20]
M. H. Loke and R. D. Barker, “Practical techniques for 3D resistivity surveys and data inversion 1,” Geophysical Prospecting, vol. 44, no. 3, pp. 499–523, 1996.
[21]
P. Tsourlos, Modeling interpretation and inversion of multi-electrode resistivity survey data [DPhil thesis], University of York, 1995.
