The adaptability of in situ remediation techniques for low soluble fractions in petroleum products such as polycyclic aromatic hydrocarbon (PAH) is generally constrained due to their limited bio-availability owing to hydrophobicity. In the present study, a numerical model is developed to evaluate the effect of unsaturated hydraulic properties, equilibrium chemical partitioning as well as coupled reactions on the fate and transport of a typical PAH (phenanthrene) originating from a surface spill. Simulation of surfactant enhanced remediation using a non-ionic surfactant (Triton N-101) resulted in significant modifications in unsaturated hydraulic properties. The presence of natural organic matter (adsorption partitioning coefficient of 8.97 × 10-4 L/mg) as well as viable bacterial consortium (specific growth rate > 3.06 × 10-7 /sec) in the soil is found to be favouring the biodegradation in order to limit the reach of phenanthrene up to a depth of 200 cm. The results suggest that selection of surfactant type and dosage affected the extent of solubility enhancement of phenanthrene (from 1.27 to 11.5 mg/L); however, ultimately the typical bio-geochemical features of the subsurface seemed to control the success of remediation. Copyright © 2017 Inderscience Enterprises Ltd.