How can a site that is almost 90% floodable can give rise to 8,000 new homes, including 900 delivered by summer 2024? It is this thorny question that the developer Grand Paris Aménagement tried to answer during the rehabilitation of the Ardoines industrial site in Vitry-sur-Seine, in Val-de-Marne (94). It is one of the largest development projects in Île-de-France including a college, 5 schools, housing, offices, shops and the future line 15 of the Grand Paris Express. The site has two construction zones (ZAC), Gare Ardoines and Seine Gare Vitry, of 49 and 37 hectares, built between the RER C railway tracks and the meander of the Seine. Total budget? More than 300 million euros.
All of the streets created will be high so that the housing will be located above the highest known rises in water, during the 100-year flood of 1910 for example. “The RER station square and the real estate programs around the square are raised by 5 meters. The day a 100-year flood arrives, the neighborhood will be flooded but residents will be able to stay on site», explains Aurélien Jutel, project director of Grand Paris Aménagement. No accommodation will be installed on the ground floor because it is a flood zone. The footprint of buildings on the ground may not exceed 50% of the surface area of the plot, in order to allow the evacuation of water in the event of flooding. Housing will be offered at controlled prices, “a very moderate price between 4700 and 4800 euros per square meter, which allows us to still sell housing in Vitry despite the housing crisis », rejoices Pierre Bell-Lloch, the mayor of the city.
A neighborhood designed to face flood risks
As for the electrical networks, they will be buried in the ZAC Gare Ardoines and placed high up in the ZAC Seine Gare Vitry where the water can rise higher. “We must not make flood conditions worse. So we provide a technical response by creating a vacuum to evacuate the water and a human response: that the life of the inhabitants is ensured.», summarizes Charles Renaut, project manager on the ZAC Gare Ardoines within Grand Paris Aménagement. “May residents be safe», adds the mayor.
The hydraulic frames, a kind of buried basin serving as a buffer space, positioned under the bridge which crosses the railway tracks, make it possible to recover water during a flood. The entire district, which should be delivered gradually until 2027, has therefore been designed to address the risk of flooding. While the city is currently not designed to cope with large-scale floods, this exceptional event was integrated into the design of the project. “We are building the future of Vitry on a piece of territory», concludes Stéphane Pourrier, the urban architect.
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