The La Roche drinking water treatment plant is a vital and strategic tool. Since 2010, it has been completely rebuilt, allowing it to treat 160,000 m3 with a possible extension to 200,000 m3 of water per day. It can thus produce at least the equivalent of 45 Olympic pools per day.
The work has just been completed. Nantes Métropole has allocated €71.5 million to it, supplemented by the Loire-Bretagne Water Agency (€12.5 million) and the Department (€6 million). The effects of climate change and population growth are leading the community to ensure that water supplies are sustainable. The drought of 2022 showed how fragile the balance is in this area.
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La Roche-sur-Yon launches its new wastewater treatment plant project
Better treatment of Loire water
The new plant is now more efficient in treating the turbidity of the water collected in the Loire. The phenomenon of muddy plugs, characteristic of estuaries, affects the production of drinking water in Nantes. It is encountered when the flow of the Loire is low and accentuated during high tidal coefficients. The sediments loaded with organic matter form a zone of very high turbidity, temporarily reducing the treatment capacity of the La Roche plant. The new installations are more efficient and should make it easier to treat this turbid water and maintain the conformity of the drinking water supplied to residents.
Blueprint
At the same time, a new sanitation master plan adopted on June 28 by the Metropolitan Council aims to reduce wastewater discharges into natural environments within fifteen years. By making its twenty-five treatment plants more reliable, renewing and resizing its pipes, or building storage and restitution basins on the banks of the Erdre, this plan should reduce annual wastewater discharge flows by 80% and produce 40 GWh/year of biomethane by 2050.
€40 million to save the Loire: an ambitious project from the Region
Affirming its priority for the reconquest of water resources, the Pays de la Loire Region has invested heavily in restoring the Loire and its watersheds. The 2021-2026 rebalancing work program is entering its final phase with remodeling interventions on the old navigation structures and the creation of a transition zone upstream of Nantes. €40 million will be devoted to it, co-financed by the Region (€11.26 million), the State and the European Union.
The actions concern the raising of the river bed, the restoration of hydraulic annexes, transversal communication and animation actions, as well as the management and acquisition of wetlands. Thus, the Council validated, among other things, the emblematic operation in Sainte-Luce-sur-Loire. Construction of the “Bellevue” sill will begin in the fall of 2024 in order to recreate a transition zone between the downstream estuarine Loire, deep and channeled, and the upstream Loire to be restored.
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