29/09/2024
Soletanche Bachy France: An 18,000 m³ water retention basin in Clichy-sous-Bois.
Soletanche Bachy France is involved in the construction of Lot 1 of the new stormwater retention basin in Clichy-sous-Bois and its annexes for connections to the existing system. Built in a constrained environment, this complex structure will have a positive impact on the environment as it contributes to flood prevention and water quality improvement.
The Maurice Audin basin is 42 m in diameter and 20 m deep when in operation. It replaces an existing 10,000 m³ water retention basin, which was undersized and therefore discharged into an open basin. Soletanche Bachy France was chosen by the Conseil Départemental de la Seine-Saint-Denis for the special works package for the new basin.
A site with high organizational demands
The basin site is located in an environment constrained by the T4 tramway on one side, an 11-storey tower on the other, and a school complex on a third side. Access to the site was limited by the space required to turn vehicles, an important parameter for logistics and deliveries. Work schedules, the techniques used and the planning of the various stages were therefore carefully coordinated.
The project was carried out in several phases:
- Geotechnical site investigation
- Injection of pre-treatment, backfill and installation of barrettes
- Pre-treatment of diaphragm walls and barrettes
- Production of diaphragm walls
Geotechnical site investigation
The first phase of Lot 1 of this project involved additional investigation work: the teams carried out soil pollution analyses and dimensioned the structure. “These analyses are important because they determine the volumes and the choice of appropriate channels for drill cuttings”, explains Antonioluca Manno, Works Director at Soletanche Bachy France.
Pre-treatment injection and filling phase
This injection phase was used to treat the ground against gypsum dissolution phenomena, which are very pronounced in the area. Injections were applied at the base of the structure and in the contact zone with the diaphragm wall to ensure stability during excavation. In all, 280 boreholes and 80 injections were drilled to a depth of 74 m. Twelve Barrettes were also installed during this phase.
Installation of Diaphragm walls
Once these steps had been completed, the diaphragm walls installation phase could begin. Crews used a KS hydraulic grab, a Hydrofraise® and a handling crane. A total of 30 diaphragm walls panels were installed at a depth of around 37.5 m. The thickness of the diaphragm walls was optimized, reduced to 0.82 m, a saving of 20 cm on the initial solution.
Congratulations to the teams on the completion of this project!
How Soletanche Bachy reduces its carbon footprint on site ?
On this site, the teams from Soletanche Bachy France used a battery pack for the treatment plants and slurry mixing units. This system accumulates electrical power from the grid at night and redistributes it during the day. Thanks to this system, CO2 emissions, vibrations in the area and the use of non-road diesel have been greatly reduced. In addition, low-carbon CEMIIIC cement was also used on the site.
