Stormwater Management at the CEA Saint-Aubin Station
Overview
Part of the Grand Paris Express Line 18 metro project, a new mobility hub was developed to enhance connectivity between transportation modes for commuters traveling through the Paris-Saclay area
The site required design measures to support sustainable stormwater management. Contractors installed a series of swales and open-air retention basins — green drainage systems (SuDS) designed to collect stormwater runoff and allow it to infiltrate into the soil.
Due to site-specific environmental conditions and groundwater protection requirements, the project team needed a solution that could help treat runoff during infiltration and prevent pollutants from reaching the shallow groundwater table.
Challenge
The site had an extremely shallow groundwater table located less than one meter below the infiltration structures. Retention basins and swales served as the primary infiltration system, collecting runoff from more than 13,000 m² of surrounding roadway surfaces across approximately 4,975 m² of basin and swale area.
This configuration increased the potential for pollutants carried by stormwater runoff to reach shallow groundwater during infiltration, creating a heightened risk of contamination. Without effective treatment, the project could have failed to meet both regulatory requirements and environmental protection objectives.
Regulatory authorities DDT91, the Essonne departmental government body overseeing land planning and environmental compliance, and SyAGE, the local water authority responsible for watershed and stormwater management, therefore required protective measures to safeguard groundwater resources. A reliable treatment solution was essential to support the planned infiltration approach while reducing pollutant transfer and protecting groundwater quality.
Solution
The project team selected OSMORIA® Geoclean® Origin, a depolluting aquatextile engineered to capture hydrocarbons and PAHs carried by stormwater runoff as water infiltrates through the system. Its textile matrix supports irreversible hydrocarbon fixation on the filaments while maintaining permeability, allowing treated water to continue infiltrating into the soil.
Beyond filtration alone, the aquatextile is designed to optimize the natural biodegradation process. By attracting and supporting native soil microorganisms through available natural mineral nutrients, OSMORIA® Geoclean® helps accelerate the breakdown of hydrocarbons fixed on its fibers, creating a self-sustaining treatment action during infiltration.
Installed across approximately 5,000 m² of open-air retention basins and swales, with 15 cm of topsoil placed above the aquatextile, OSMORIA® Geoclean® integrated into the site’s green drainage infrastructure without changing the planned infiltration approach. This provided the project team with a reliable, maintenance-free solution to treat runoff during infiltration, reduce pollutant transfer, and support long-term protection of shallow groundwater quality.
