GPR Mapping toluene infiltration in a sand model

The high resolution GPR technique of 1.5 GHz antenna is applied for mapping infiltrated dense non-aqueous phase liquid DNAPL (here toluene) in a partially saturated sand medium with time. A model box (83*9.5*61 cm3) is filled with a medium sand which is saturated with water at the lowermost 18 cm. The model contains five prismatic objects of fine (objects 1, 4) and coarse sand (objects 2, 3, 5). A toluene is infiltrated from a single driplet at the centre of the upper surface. Georadar measurements (1.5 MHz) from the external surfaces show that mapping toluene is possible in the partially saturated zones of objects 1, 2 and 4 and hardly in the other areas. The weak reflections within the low saturated region may be caused by a weak electromagnetic impedance contrast at the interface to the toluene zone.