Approche géostatistique appliquée à l’évaluation d’un état de pollution des sols dans le cadre d’une session de site industriel

This study focuses on the estimation of masses of contaminants in place inside a production site and the quantification of the spatial uncertainty related to the location of these masses. The aim is to provide an assessment of the current soil contamination (current status) before the transfer of the site to another indus-trial company. The proposed methodological approach relies on geostatistical modeling of the soil contamination by using a simulation method that generates a large number of realistic and equiprobable 3D images of grades for soil contaminants of interest. The images are realistic because they reproduce the grade data and their observed spatial variability. They are equiprobable in that they all have the same probability to represent the actual soil contamination. To assess the soil contamination before the site transfer, the masses of contaminants in place and the associated uncertainty can be estimated from the simulations, for the whole site or by zone. Using the simulations, it can be identified the locations where potential soil contami nation sources are likely to be or not found with high enough confidence, and those where the soil conta mination is uncertain. The sources of contamination are defined as corresponding to the areas where the vertical accumulation of contaminant mass exceeds some critical threshold above the saturated zone.