Geotechnical Properties of Clay Soil Contaminated with Different Types of Oil

Abstract

The soil contaminated by oil product has geotechnical and environmental issues that rise from leakages in oil storage tanks, accidental spills, and supply and transition pipelines. For instance, a leakage has been recorded in the refinery station near the vicinity of Nineveh province where the soil’s site is known with its high plasticity. The present study investigated comprehensively the engineering properties of soil contaminated with crude oil, diesel, kerosene, and gasoline at both dry and wet sides of compaction curve. Results show that the shape of the compaction curve changes to a double peak curve with a reduction in maximum dry density of 6% due to oils contamination. The soil plasticity decreases by approximately two-third upon contamination. Furthermore, the swelling percent increases by 1.9 to 2.5 times on dry side and by 3.8 to 4.3 times on wet side. The swelling pressure also increases by 1.2 times for soil contaminated with 5% diesel or 4% kerosene, while it decreases with crude oil. Strength results show that the cohesion (C) decreases by 45.2, 60.8, and 78.8% upon soil contaminated with 18% crude oil, 17% diesel, and 17% kerosene respectively; however, the corresponding angle of internal friction (ϕ) increases by several degrees. Likewise, a considerable reduction in the unconfined compressive strength is reported upon contamination. Moreover, the permeability decreases by 25% to 50% on dry side while it increases 2 times on wet side.