Notre Dame de Riez Chemin de l'Etang Wastewater Treatment Plant, Soullans

Notre Dame de Riez Chemin de l'Etang is a municipal wastewater treatment plant located in Soullans, within the Pays de la Loire region of western France. The plant serves a population of 2,533 and operates as part of the local sanitation infrastructure for the Vendée department. Its coastal proximity places it within 10 kilometers of the Atlantic Ocean, making its discharge management environmentally significant. As a secondary treatment facility, the plant provides biological treatment to reduce organic matter and suspended solids before discharge. With a designed capacity of 2,830 m³/day and an average daily flow of 451.88 m³/day, the plant operates well below its capacity, indicating room for future growth. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), secondary treatment is the minimum standard for freshwater and estuarine discharges from agglomerations of this size, though coastal discharges may require additional treatment in sensitive areas. The treated effluent is discharged into the local watershed, which drains into the Atlantic Ocean via the Vendée coastal rivers. The region supports diverse aquatic life and is part of the Marais Breton, an important wetland area for migratory birds. The plant's coastal location necessitates careful monitoring to protect marine water quality and nearby recreational beaches.

The plant discharges into the coastal watershed of the Vendée, which flows into the Bay of Biscay in the Atlantic Ocean. This area includes the Marais Breton, a large wetland complex that provides critical habitat for migratory birds and supports diverse aquatic species. The proximity to the coast means that treated effluent can influence nearshore water quality, particularly in sensitive estuarine and marine environments.