GPR Application for Mapping Toluene Infiltration in a Heterogeneous Sand Model

The high resolution radar technique is applied for monitoring infiltrated hydrocarbon liquids in a partially saturated heterogeneous sand medium as a function of time. Here I used a frequent LNAPL (light non-aqueous phase liquid) contaminant of toluene, which is electrically insulating and has a low relative dielectric constant er of 2.2. In a laboratory experiment, a thin model box of 83×9.5×61cm3 was filled with a medium sand (for sand grains er=4.7, σ<1mS∕m). The sand was saturated with water in the lowermost 18cm thick zone, and dry to partially-saturated in the overlying layer. Five small prismatic objects of fine sand (objects 1, 4) and coarse sand (objects 2, 3, 5) were embedded at different positions within the sand model. For a total time of 80min, less than 1liter toluene was infiltrated from a drip-source at the center of the upper surface of the model. Radar measurements from one side of the model using 1.5GHz antenna showed that mapping toluene is in principle possible in the fully and partia...

[1]  J. M. Price,et al.  Dielectric properties of reservoir rocks at ultra-high frequencies , 1985 .

[2]  W. A. Wensink,et al.  Dielectric Properties of Wet Soils in the Frequency Range 1-3000 MHz1 , 1993 .

[3]  A. P. Annan,et al.  Ground-penetrating radar for high-resolution mapping of soil and rock stratigraphy , 1989 .

[4]  L. Orlando.  Detection and analysis of LNAPL using the instantaneous amplitude and frequency of ground‐penetrating radar data , 2002 .

[5]  David L. Grumman,et al.  Experiments on the Detection of Organic Contaminants in the Vadose Zone , 1995 .

[6]  A. P. Annan,et al.  Electromagnetic determination of soil water content: Measurements in coaxial transmission lines , 1980 .

[7]  Müller,et al.  GPR study of pore water content and salinity in sand , 2000 .

[8]  Bridget R. Scanlon,et al.  Hydrologic issues in arid, unsaturated systems and implications for contaminant transport , 1997 .

[9]  S. A. Hagrey,et al.  Preferential flow: first results of a full-scale flow model , 1999 .

[10]  A. Benson.  Applications of ground penetrating radar in assessing some geological hazards: examples of groundwater contamination, faults, cavities , 1995 .

[11]  A. Peter Annan,et al.  Ground‐penetrating radar monitoring of a controlled DNAPL release: 200 MHz radar , 1994 .

[12]  Steven A. Arcone,et al.  High resolution of glacial ice stratigraphy: A ground‐penetrating radar study of Pegasus Runway, McMurdo Station, Antarctica , 1996 .

[13]  P. N. Sen,et al.  A self-similar model for sedimentary rocks with application to the dielectric constant of fused glass beads , 1981 .

[14]  Estella A. Atekwana,et al.  High Conductivities Associated With an LNAPL Plume Imaged by Integrated Geophysical Techniques , 1998 .

[15]  R. Jeanloz,et al.  Introduction to the physics of rocks , 1994 .