Renovation of the Clichy-la-Garenne wastewater treatment plant
Civil engineering works, poles and cover slab for basin T30.
Built almost 160 years ago, the Clichy-la-Garenne pre-treatment plant (operated by the Paris Wastewater Authority (SIAAP)) is the transit point for a significant proportion of wastewater from the Paris conurbation.
The large-scale renovations to this plant include the building of a new 70,000m³ storage basin for surplus rainwater, the modernisation of the current pre-treatment unit and the building of a second unit.
Order 1 works began in 2019 with the laying of diaphragm walls, the coupling beam and apron of this imposing T30 basin, measuring 71.5m in diameter and 25.6m deep. These works were executed by the Soletanche Bachy – Sefi-Intrafor consortium and completed in July 2022.
SIAAP then entrusted the Maïa Sonnier (agent) – Pinto (co-contractor) – SADE Special Works (co-contractor) consortium with Order 3, to follow on from Order 1 works.
This task consists in executing all interior civil engineering works: the poles, beams, cover slab and concrete haunch of the storage and return basin. Works also include the creation of a technical station and the sewerage inflow membrane.
In April 2022, our teams began the pouring of the 53 22m-long poles and 10 concrete walls in 2 lifts which will hold an automatic rinsing system for sediment deposited on the apron (tilt troughs).
The construction of a circular footbridge around the basin perimeter should be completed by the end of this year. This will enable access to the base of the concrete well. The laying of 60 prefabricated beams is also due for completion at this time.
The 50cm-thick cover slab is composed of 217 watertight prefabricated pre-slabs. The cover slab, once complete, will be covered with topsoil.
The basin is to be delivered, following 12 months of works, in April 2023.