AquaConSoil 2025

Topic 3.1: Data Integration and Harmonization

Geostatistics for ground sorting during harbour-basin excavation: multi-parameter and multi-threshold management in an uncertain context

Authors : Erwan Le Priol, Jean-Yves Hardy (Haropa), Claire Faucheux, Hélène Binet (Geovariances)

Port Seine-Métropole Ouest (PSMO) is a multimodal port platform located at the confluence of the Seine and Oise rivers in France, spanning the municipalities of Achères, Andrésy, and Conflans-Sainte-Honorine. Covering approximately 100 hectares, this port is focused on construction and public works activities, offering an efficient logistics and transport solution that provides an alternative to road transport for construction and development projects in Greater Paris.

During the first phase of construction, the excavation and opening of the harbor basin will generate over 500,000 m³ of excavated soil. Effectively managing this soil presents a major challenge due to the significant costs involved. Therefore, accurately estimating the quantities of excavated soil based on pollution levels is crucial. The goal is to anticipate the waste routes for the soil, allowing for effective management of volumes and associated budgets.

To address this issue, geostatistical methods have been employed, particularly turning bands simulations. This expertise focuses on nine parameters that can lead to classifications into three types of waste storage: ISDI+ (inert waste storage centers with sulfate issues), ISDND (non-hazardous waste storage centers), and biocenter waste routes. Soils with the lowest concentrations of pollutants will be directed to ISDI (inert waste storage centers). Quarry backfilling has also been considered a potential waste route, utilizing a criterion based on the sulfate to soluble fraction ratio.

Several scenarios incorporating different waste routes have been tested, enabled by the speed and ease of post-processing offered by geostatistical modeling. For each type of storage, the total volume of excavated soil and the volume associated with each parameter have been calculated. This process takes into account acceptance thresholds and uncertainties related to data and interpolation, using computations of threshold exceedance probabilities. Additionally, the masses associated with each parameter for each storage type have been calculated.

Finally, mappings of the waste routes have been produced, according to the excavated depths and considering the mesh size used during excavation. Additional maps showing the downgrading parameters for each storage have also been delivered.

This robust methodology, which quantifies uncertainties, helps secure the budget during a critical phase of the project.