May 25th, 2021
VL8 collector, Valenton: work is progressing
The VL8 collector will connect the V10 stormwater ogee (in Athis-Mons) to the SÉSAME pumping and purification station (in Valenton). The project has multiple objectives: to strengthen and secure the sanitation network, but also to avoid the risk of discharge into the natural environment. The project is also contributing to ensuring that the Seine is “swimmable” by the 2024 Paris Olympic Games.
The project has multiple objectives: to strengthen and secure the sanitation network, but also to avoid the risk of discharge into the natural environment. The project is also contributing to ensuring that the Seine is “swimmable” by the 2024 Paris Olympic Games.
Work package 0 includes the various shafts (entry, exit and reversing tunnel) for the tunnel boring machines. Work, which is mainly within four sectors, began in October 2020 with the confirmed Valenton phase, in the SIAAP water treatment plant.
The teams of the consortium led by Soletanche Bachy France have been involved in development work since October 2020, including an access road independent of the plant, a fence, a sanitation system and a work platform. This work also included the construction of a modular retaining wall 70m long and 6m high. This solution was proposed by the consortium and accepted by the SIAAP, allowing the removal of a containment mound present on the site of the future diaphragm wall.
The preliminary work, involving 134 boreholes at a depth of 46m, was completed in mid-February. These grouting particularly focused on the upper levels of fill, as the future structure is to be built on a former landfill site.
Meanwhile, the installations have been completed, giving way to diaphragm wall workshops comprising a heavy grab and an HF7 Hydrofraise®. The work to be constructed involves a diaphragm wall, 135m long, 1m thick and 45m deep. This circular shaft will be connected to a reversing tunnel which will allow a tunnel boring machine to be launched towards the next shaft in Orly. It is located just a few meters from an existing structure, the Sesame shaft, completed by Soletanche Bachy in 2003.
The diaphragm wall work should be completed in June, followed by work on a temporary injected base to control the pumping rate during the earthworks.
Work on the Vigneux-sur-Seine shafts should also have started by then.
