Kejadian tumpahan minyak kerap berlaku semasa pengangkutan minyak, penyimpanan, pengeluaran dan pemprosesan akibat kebocoran saluran paip dan tangki simpanan bawah tanah. Tumpahan minyak boleh mengubah sifat-sifat tanah dan mencemarkan air bawah tanah apabila ia mencapai meja air bawah tanah. Biasanya, minyak yang kurang padat akan terapung di air dan berhijrah dengan air bawah tanah. Teknik mengesan tumpahan minyak di kawasan tumpahan minyak yang besar adalah sukar dan mahal. Oleh itu, penghijrahan minyak (LNAPLs) dalam tanah boleh dikaji. Dalam kajian ini, ujian tangki dua dimensi dijalankan untuk mengkaji penghijrahan diesel. Gradien hidraulik yang berbeza disimulasikan untuk mengkaji pengagihan diesel di dalam tanah. Keseriusan tumpahan minyak juga dikaji dalam kajian ini. Tingkah laku diesel dalam sampel tanah dianalisis. Pertama, kemurungan pinggiran kapilari di tempat pencemaran telah dianalisis. Kemurungan pinggir kapilari berkurangan apabila kecerunan hidraulik meningkat. Kemurungan pinggir kapilari meningkat seiring peningkatan jumlah diesel. Kemudian, plum pencemaran tegak maksimum sebelum mencapai jadual air bawah tanah telah dianalisis. Jari radiasi pencemaran tegak maksimum meningkat apabila jumlah ditambah diesel meningkat. Penghijrahan diesel dianalisis secara kuantitatif dan kualitatif. Halaju perjalanan diesel berkurang sebagai kecerunan hidraulik. Diesel berhijrah ke pinggir kapilari dan berpindah lebih cepat disebabkan oleh aliran air tanah pada kecerunan hidraulik yang rendah. Diesel itu berhijrah ke kawasan yang lebih rapat dan lebih perlahan pada kecerunan hidraulik yang lebih tinggi. Untuk membuktikan perkara ini, kepekatan diesel pada akhir tangki air dianalisis. Kesimpulannya, hubungan antara penghijrahan diesel dan kecerunan hidraulik boleh ditubuhkan. Hubungan antara plum pencemaran vertikal maksimum terhadap jumlah tumpahan minyak juga ditubuhkan.
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Incidents of oil spillage can easily happen during oil transportation, storage, production and processing due to the leakage of pipeline and underground storage tank. Oil spill can alter the soil properties and pollute the groundwater once it reaches the groundwater table. Usually, the oil which is less dense the water will float on the water and migrates with the groundwater. The tracing technique for oil spill of large area of oil spill is difficult and expensive. Hence, the migrating behaviour of Light Non-Aqueous Phase Liquids (LNAPLs) in soil can be studied. In this research, two dimensional tank tests were carried out to study the lateral migration of diesel. Different hydraulic gradients of groundwater table were simulated to study the redistribution of diesel in soil. Different severity of oil spill was also studied in this research. The migrating behaviour of diesel in the soil sample was analysed. First, depression of capillary fringe at the point of contamination was analysed. Depression of capillary fringe decreases as hydraulic gradient increases. Depression of capillary fringe increases as volume of diesel increase. Then, the maximum vertical contamination plume before reaching groundwater table was analysed. The radius of maximum vertical contamination plume increases as the volume of diesel added increases. The lateral migration of diesel was analysed quantitatively and qualitatively. Travel velocity of diesel decreases as the hydraulic gradient. Diesel migrated down to capillary fringe and migrated much faster due to ground water flow at low hydraulic gradient. The diesel migrated more evenly and slower to neighbouring soil at a higher hydraulic gradient. To prove this point, concentration of diesel at the end of water tank was analysed. In conclusion, the relationship between lateral migration of diesel and hydraulic gradient can be established. The relationship of maximum vertical contamination plume against the volume of oil spill was also established.
Lateral migration of lnapl contamination due to the variation of hydraulic gradient / Tan Zhi Hern