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Articles by Umar Hamzah
Total Records ( 2 ) for Umar Hamzah
  Zulfahmi A. Rahman , Umar Hamzah , Mohd. R. Taha , Norsheila S. Ithnain and Noorulakma Ahmad
  Problem statement: Oil contamination due to accidental spillage or leakage brings hefty damage to the environments. It percolates steadily into subsurface environments and contaminates the soil and water system. Hydrocarbon contamination has not just affected the quality of the soil but will also alter the physical properties of oil-contaminated soil. Approach: This study presented the geotechnical properties of oil-contaminated soils as well as uncontaminated soils for comparison. Testing programs performed on the studied soils included basic properties, Atterberg limit, compaction, permeability and unconsolidated undrained triaxial tests. The base soils used were originated from weathered basaltic rock of grades V and VI. Soil samples were artificially contaminated with 4, 8, 12 and 16% oil of the dry weight of based soils. Results: The results showed that the oil contamination decreased the liquid limit and plastic limit values for both grades of weathered soils. For soil grade V, the decrease in plastic limit and liquid limit were represented by 21 and 39%, respectively. Meanwhile, for soil grade VI, the drop was significantly high for liquid limit (39%) and lower for plastic limit (19%) if compared to soil grade V. The oil-contaminated soils also indicated a lower Maximum Dry Density (MDD) and optimum water content if compared with uncontaminated soils. The MDD for soil grade V and VI decreased from 1.67-1.50 and 1.60-1.55 g cm-3, respectively. The OMD values dropped from 23.5-17.5% for soil grade V and 23.0-16.5% for soil grade VI when oil contents were increased. A reduction in permeability was observed as a result of the oil contamination. The permeability of soil grade V and VI decreased from 3.74-0.22 and 2.65-0.22 cm sec-1, respectively. In terms of undrained shear strength, Cu was clearly affected by the increase in oil content in contaminated soils. Both soil grades showed stress dependant behavior with a brittle mode of failure. The Cu values for uncontaminated soils of both grades were 126 and 106 kPa and then dropped to very close values of 35 and 32 kPa at oil content of 16%. Conclusion: The results showed that the addition of oil has adverse effects to the geotechnical properties of the studied residual soil. Contaminated residual soils might be used for geotechnical purposes and these results will benefit to engineers or decision makers in recycling or re-using of contaminated soils.
  Umar Hamzah , Mark Jeeva and Nur Atikah Mohd Ali
  Monitoring of contaminated water and soil in waste disposal sites is normally carried out by chemical analysis of surface water, leachate and soils as well as by geophysical measurements. Leachate is defined as any contaminated liquid or wastewater generated from rain water percolating through solid waste materials, accumulating contaminants and moving into subsurface and surrounding areas. A study was carried out to detect the leachate movement at Sungai Sedu landfill located on ten square acres near Banting town. Geologically, the study area is underlined by Holocene marine clay of Gula and Beruas Formations sitting on top of metasedimentary rocks of Kenny Hill formation. Geophysical surveys using techniques 2D electrical resistivity imaging, Vertical Resistivity Profiling (VRP) as well as geochemical analysis on soil and water samples were used in this study to investigate the level of leachate migration from the dumping spot into the surrounding areas. This was based on characterizing the measured electrical resistivities and analyzing the heavy metal concentrations. The 2D electrical imaging surveys were carried out on 8 profiles while the VRP surveys were conducted in 6 boreholes. Based on resistivity imaging sections, the leachate was detected to migrate at about 3-5 m depth. Basically the resistivity of leachate is less than 1 Ωm. The concentrations of heavy metals also showed that the leachate has migrated into the nearby river. The concentrations of heavy metals in river bank soil, leachate and surface water samples are high and exceeded the background values especially Ni, Mn, Zn, Cr and As. Conductivity of the river bank soil, leachate, surface water and the surrounding soil samples were approximately around 6600 and 20000-50000 μS cm-1, respectively with pH values of 3-5. The high concentrations of heavy metals and soil conductivities indicate the possibility of leachate migration from the dumping site to contaminate the nearby river, soil and groundwater of the study area.
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