## 2 Impact of Oil Pollution on Geotechnical Features of Soil
### Atterberg Limits
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Soil Properties**} & \multicolumn{2}{c}{**Uncontaminated Soil**} & \multicolumn{2}{c}{**Contaminated Soil**} \\ \cline{2-5}  & **Mean** & **S.D** & **Mean** & **S.D** \\ \hline Natural moisture content (\%) & 14 & 1.56 & 10.5 & 2.43 \\ In situ density (kg/m\({}^{3}\)) & 1360 & 0.16 & 1080 & 1.87 \\ Liquid limit (\%) & 38 & 0.86 & 42 & 1.77 \\ Liquid limit (\%) (exp. results) & - & - & 46.71 & 1.44 \\ Plastic limit (\%) & 17.42 & 1.95 & 22.9 & 2.84 \\ Plastic limit (\%) (exp. results) & - & - & 26.17 & 2.96 \\ Plasticity index (\%) & 0.58 & 1.91 & 19.1 & 2.37 \\ Plasticity index (\%) (exp. results) & - & - & 20.54 & 3.91 \\ Flow index (\%) & 8.58 & 0.67 & 10.5 & 0.84 \\ Maximum dry & 1750 & 1.25 & 1680 & 0.11 \\ Density (kg/m\({}^{3}\)) & - & - & 1450 & 0.15 \\ OMC (\%) & 16.48 & 1.53 & 12.5 & 1.05 \\ OMC (\%) (exp. results) & - & - & 15.52 & 0.89 \\ UCS (kPa) (average of three tests) & 0.58 & - & 0.38 & - \\ Cohesion (kPa) (average of three tests) & 0.63 & - & 0.2 & - \\ The angle of internal friction (average of three tests) & 18 & - & 14 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Index properties of the variant soils. Figure 2: Influence of oil content on Atterberg limits of CL samples. (**a**) Liquid limit; (**b**) plastic limit. The impact of fuel oil pollution and the rise in the Atterberg limits of polluted soil is due to an increase in the double-layer thickening of mud metals such as iolite, kaolin, and chlorite. Table 4 and Figure 3 show the characteristics of the soil limits of the plastic CL that were researched, and it was discovered that the feature tends to grow distinctly as the oil substance rises. The value of the plastic limit increases approximately from 22% to 55%, the liquid limits increase approximately from 45% to 61% with a mild regression, and the plastic indicator drops approximately from 20% to 5% as a result [24]. \begin{table}
\begin{tabular}{l c} \hline \hline
**Parameter** & **Quantity** \\ \hline Clay, Silt, Sand, and Gravel (M.I.T. Categorization) & 3\%, 89\%, 7\%, 1\% \\ L.L., PL., PI & 23.9, 45.5, 21.6 \\ Water Content & 3.90\% \\ Organic Material Content & 3.64\% \\ P.H. (in 27 \({}^{\circ}\)C) & 8–8.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Overview of initial soil characteristics soils. Figure 3: Atterberg limits and plasticity index under the influence of oil content. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & & & & & & & & & & & \\ \hline \multicolumn{1}{c}{\multirow{2}{*}{**Attereberg Limits**}} & \multicolumn{2}{c}{**Polluted Soil/** (Exp. Results)**} & \multicolumn{2}{c}{**Polluted Soil/ (Exp. Results)**} & \multicolumn{2}{c}{**5\%**} & \multicolumn{2}{c}{**10\%**} & \multicolumn{2}{c}{**20\%**} & \multicolumn{2}{c}{**5\%**} & \multicolumn{2}{c}{**10\%**} & \multicolumn{2}{c}{**20\%**} \\ \hline Liquid limit (\%) & 42 & 46.71 & 42.22 & 41.80 & 40.64 & 37.30 & 36.80 & 35.50 & 38.50 & 37.90 & _36.60_ \\ Plastic limit (\%) & 22.9 &  
Water molecules contain a positive charge on one side and a negative charge on the other, making them bipolar. H2O is drawn from the negative-clay particles and cations in the double layer. H2 in water molecules is absorbed by the oxygen in the mud layer to create hydrogen bonds. All the water bound to mud molecules by engagement is double-layer water. Adsorbed water is the internal layer of double-layer water adhered tightly by mud. This arrangement of H2O in mud molecules provides clay soils with plastic characteristics. Free H2O is water in the porous space that is not absorbed by mud molecules and travels readily through the soil. Free water influences the liquid behaviour of the soil [25]. Ore oil coats mud molecules and prevents water from reaching double-layer water. Therefore, more water is required for plastic topsoil, which may explain the higher plastic limit. Water added to the soil within the experiments will join the free-water layer if the oil orients the soil particles.