Surveillance de la dépollution du goudron de houille dans un sol contaminé à l'aide de méthodes électro-géophysiques

Titre : Surveillance de la dépollution du goudron de houille dans un sol contaminé à l'aide de méthodes électro-géophysiques

Title : Monitoring the remediation of coal tar in contaminated soil using electro-geophysical methods

Abstract: During the past two decades, the remediating and monitoring of polluted sites have become an important issue. Health and ecological regulations in developed and progressing countries are more restrictive concerning the abandoned polluted sites. Classical well monitoring techniques are not enough to monitor soil characteristic change in subsurface. Among all geophysical techniques, electrical methods showed their ability to monitor clean-up programs in these sites.
Spectral induced polarization (SIP) technique (also called complex resistivity) is a method in near surface geophysics to measure complex electrical resistivity of a medium in the frequency domain. Many geophysical techniques help us to discover organic contamination, the bedrock position, mineral ores, ancient buildings and many other valuable stuffs on the subsurface. The other geophysical method was used is time domain reflectometry (TDR) that has been developed to measure relative dielectric permittivity, water content and temperature in homogeneous or heterogeneous porous media. This thesis is a challenge to evaluate efficiency and potential of SIP and TDR for a long-term monitoring of dense non-aqueous phase liquids (DNAPLs) recovery in contaminated porous media in the laboratory. Different sets of experiments designed to study the impacts of temperature and saturation changes on electrical complex resistivity and relative permittivity of saturated porous media on isothermal and non-isothermal conditions were examined in different 1D columns. The measurements were made with different couples of pollutants and fluids (i.e. coal tar/water, chlorinated solvent/water and canola oil/salty ethanol) in porous media simulated with glass beads of 1 mm diameter.
Our findings concerning to temperature change show that experimental data of relative permittivity and complex resistivity of pure water obey empirical models validating our experimental setup and protocol. Results demonstrated that the real parts of relative permittivity and electrical resistivity are functions of temperature. While the imaginary part of relative Permittivity has not been studied, but our observations in the samples of DNAPLs indicated that the temperature increase leads to decrease in imaginary parts of complex electrical resistivity of DNAPLs. Two sets of experiments examined impacts of saturation changes in these two geophysical parameters. Our findings show that due to high resistivity of oil and coal tar, increase in water/oil saturations led to decrease in resistivity and phase. Interpreting experimental data showed that resistivity and relative permittivity measurements were compatible with Generalized Archie’s law and complete refractive index method (CRIM) model, respectively. Moreover, the effects of temperature and saturation on complex resistivity have a secondary effect on frequency domain and Cole-Cole parameters.
The results from the laboratory measurements will be used in the real conditions in field measurements in a remediation program.

Thèse, soutenue le 30 janvier 2020 devant le jury  :

Myriam SCHMUTZ, Professeure à Bordeaux INP, rapporteur
Frédéric NGUYEN, Professeur à l’Université de Liège, rapporteur
Loïc LABROUSSE, Professeur des universités, SU, ISTEP UMR7193, examinateur
Vincent ALLEGRE, Maître de conférences, Université de Bordeaux, examinateur
Roger GUÉRIN, Professeur des universités, SU, METIS UMR7619, directeur
Alexis MAINEULT, Chargé de recherche, CNRS, METIS UMR7619, co-directeur
Jacques DEPARIS, Ingénieur de recherche au BRGM, co-encadrant
Hossein DAVARZANI, Ingénieur de recherche au BRGM, co-encadrant