In Iraq, the risk of soil pollution by petroleum products increases with the growth of oil exploration, production and shipping large quantities of oil through pipelines over thousands of kilometers. Numerous oil spills have been documented recently in many sites due to damage in the oil industry infrastructures, which have led to soil contamination causing serious environmental hazards and deterioration to the soil and its engineering properties. So, it is essential to investigate the impact of oil leakage through the soil stratum consequently, assessing the eligibility of the contaminated soil for construction projects or identifying the appropriate treatment method. The paper investigates the general behaviour and the associated variations in the geotechnical properties upon contamination of soil in Thi-Qar Governorate which is characterised by many oil refineries. Disturbed soil samples are artificially contaminated with crude oil ranging from 0% to 10% of their dry weight. Testing programs have been conducted on the soil incorporated with conventional tests such as grading, Atterberg limit, compaction and consolidation tests as well as electrical resistivity measurements. To achieve a reliable assessment, the findings are directly compared to those of the uncontaminated soil. The final outcomes of this study indicate that an increase in oil content causes the distribution of the aggregate size curves to shift from fine to coarse ranges. Also, liquid limit, plastic limit, and plasticity index increased markedly upon contamination. Moreover, oil added to the soil mixture caused an increase in the maximum dry density of the soil and a decrease in the corresponding optimum moisture content. In addition, the consolidation characteristics of the polluted soil have been affected slightly and the electrical resistivity data was sensitive to the amount of pollutant
