To keep up with population growth and rising economic activity, SIAH – the water management association bringing together 35 towns in the Le Croult and Le Petit Rosne valleys in eastern Val d’Oise, north of Paris – undertook to double the capacity of the Bonneuil-en-France wastewater treatment plant before it reached saturation point.
911 metres of precast jacking pipes used by Bessac
As part of this project, the creation of a treated water discharge tunnel was entrusted to a consortium led by Bessac and including Soletanche Bachy Fondations Spéciales and Setec in 2021. The objective was to connect the wastewater treatment plant to the Garges-Epinay rainwater collector in Dugny.
The tunnel was built entirely with pipes made of EXEGY® ultra-low-carbon concrete under the “EXEGY® by Bessac” brand – a world first. In total, 911 linear metres of precast jacking pipes (with an internal diameter of 1.60 m and an external diameter of 1.94 m) were installed by Bessac in a single MTBM drive.
Project
Extension of the Bonneuil-en-France treatment plant in the Val d’Oise department
Project owner
SIAH (the water management association for the Le Croult and Le Petit Rosne valleys)
Project management
Bessac, Soletanche Bachy Fondations Spéciales and Setec
Time frame
2022, with commissioning scheduled for July 2023
An EXEGY® solution resulting from close collaboration between VINCI Construction subsidiaries
Standard blast-furnace cement (CEM III) solutions did not make it possible to produce concrete responding to the technical constraints for jacking pipes and go as far in reducing CO2 emissions.
With that in mind, Bessac, the materials laboratories of VINCI Construction and Soletanche Bachy, a VINCI Construction partner and the Tunnel Factory developed a special EXEGY® ultra-low-carbon formulation and executed a durability test protocol to confirm the solution’s fitness for purpose and acid resistance.
This solution, which replaces 80% of the clinker with a formulation containing blast‑furnace slag and limestone filler, shows levels of technical performance equivalent to those of standard C50/60 concrete, and has a reduced carbon footprint of 117 kg CO2eq/m3 – four times lower than that of the formulations generally used for precast jacking pipes.
0%
classic
0%
low carbon
0%
very low carbon
100%
ultra low carbon
870
m3 of EXEGY® concrete
66%
reduction in CO2*
200
tonnes of CO2eq avoided
*compared to an equivalent traditional concrete solution
An innovation in the field of precast jacking pipes
This structure is an innovation and a world first, as it features the first precast jacking pipes meeting the EXEGY® ultra-low-carbon technical standard and building on the performance-based approach consistent with the EN 206-1 concrete standard.
