Application of Magnetic Gradiometry, Magnetic Susceptibility and Electrical Resistivity Tomography in the Characterisation of the Sunyani Municipal Waste Disposal Site

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November, 2016
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Areas that surround unlined solid waste disposal sites depict high tendencies of being contaminated with leachate emanating from the waste deposits that in ltrate into the ground. For that reason, this research seeks to highlight and bring to the attention of city authorities and interest groups the alarming levels of the anthropogenic impact of dumped solid waste on the environment especially, when it pertains to the ground and its water resources using integrated geophysical methods. The integration of three geophysical methods comprising of magnetic gradiometry, magnetic susceptibility and electrical resistivity tomography has helped to characterise the SMA waste disposal site mainly due to the unlined and heterogeneous nature of the waste deposit. The results of both magnetic susceptibility and gradiometric methods displayed in anomaly maps clearly de ned the physical boundaries of the waste deposit with an approximate area extent of 82; 650 m2 which is characterised by high magnetic susceptibilities between 426 10􀀀5 SI and 9890 10􀀀5 SI. Also, an average magnetic intensity value of 32230:74 nT was recorded over the area with values generally greater than the average measured over the main waste body. They also revealed high magnetic anomalies sporadically distributed outside the main waste boundaries which are attributed to indiscriminate deposition and uncontrolled nature of the waste. Similarly, the ERT sections also revealed zones of leachate contamination and accumulation just beneath the waste body and migration pathways for leachate were also delineated with low resistivity signatures up to 43:9 :m. In spite of the success reported herein with the ERT, the research also revealed that the ERT is less e ective in estimating the thickness of the waste deposit due to leachate in ltration into the ground beneath it that masks the resistivities of the top level ground and makes it indistinguishable from the waste body. Having estimated an approximate waste thickness of about 5 m using ERT, the volume of waste expected to be reclaimed from the site for remediation purposes is estimated at 413; 250 m3.
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A Thesis Submitted to the Department of Physics, Kwame Nkrumah University of Science and Technology in partial ful llment of the requirements for the award of the degree of Master of Philosophy in Geophysics,
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