Time-lapse ground penetrating radar (GPR) imaging of used engine oil contamination

Time-Lapse Ground Penetrating Radar (GPR) was employed to study used engine oil (UEO) contamination of sandy environment in laboratory setting. GPR is a near-surface geophysical method that uses electromagnetic field to provide image of the dielectric properties of earth materials to detect structures and changes in material properties within the subsurface. This research aimed to detect, monitor and map the migration of UEO contaminant in sand. The results of this study revealed that the migration of the UEO contamination in homogeneously laid sand is non-uniform. UEO plumes were identified as high amplitude signals with enhanced reflectivity. There was a progressive decrease in GPR signal amplitudes (reflection reduction) within the contaminated area of the tank with time. This decrease of GPR signal amplitudes was interpreted as caused by the evaporation of some portion of the UEO in the vadose zone as a result of temperature increase in time and also due to the occurrence of UEO biodegradation. The time-lapse GPR proved to be an effective technique for detecting, monitoring, and mapping UEO migration within sand tank in laboratory setting.