OLLAINVILLE Wastewater Treatment Plant, La Roche, Île-de-France

OLLAINVILLE is a wastewater treatment plant located in La Roche, within the municipality of Ollainville, in the Essonne department of Île-de-France, France. It serves a population equivalent of 64,330, classifying it as a medium-to-large agglomeration under EU regulations. The plant is part of the Syndicat de l'Orge, a local intercommunal syndicate managing wastewater services in the Orge river basin. Under the EU Urban Waste Water Treatment Directive (91/271/EEC), agglomerations of this scale are required to provide secondary treatment as a minimum, with tertiary treatment mandated if the receiving waters are designated as sensitive areas. The regulatory framework ensures compliance with discharge standards to protect the local environment. The plant discharges treated effluent into the Orge River, a tributary of the Seine. The Seine flows through Paris and eventually into the English Channel via the Seine estuary. The Orge watershed supports diverse aquatic life and is an important ecological corridor in the Île-de-France region, contributing to the overall health of the Seine basin.

The plant discharges into the Orge River, which flows into the Seine River, ultimately reaching the English Channel. The Orge watershed is ecologically sensitive, supporting diverse aquatic species and serving as a migratory corridor for fish. The Seine estuary is a critical habitat for birds and marine life, making effective wastewater treatment essential for downstream water quality.