Laboratory test to assess the performance of a high-frequency GPR in the detection of a shallow fuel oil contamination

This document presents a scale laboratory test where a 2.0 GHz ground-penetrating radar (GPR) is used to assess a controlled fuel oil injection in a shallow sand tank setup. The test analyzes several scenarios involving different levels of water saturation and fuel oil contamination. The increase of water content produces a decrease in the EM wave propagation velocity, moving the reference targets to higher reflection times. The presence of the oil lens is visible as a high amplitude reflection anomaly. We use also simplified relations to obtain a first order approximation of the dielectric permittivity for each experiment. Despite the simplified approach, there is a good match between the inverted results and the values available in the literature for similar scenarios. Rather than suggesting a true quantitative procedure, these observations could be exploited in a qualitative long-term monitoring strategy in common field situations where a contaminant enters a soil matrix and moves through its pore spaces. Finally, the integration of GPR measurements with other monitoring techniques could increase the reliability of the interpretation and the sensitivity to the contaminant concentration.