The project concerns 13 municipalities in the territory: Beauchamp, Cormeilles-en-Parisis, Eaubonne, Ermont, Franconville, Herblay-sur-Seine, La Frette-sur-Seine, Le Plessis-Bouchard, Montigny-lès-Cormeilles, Pierrelaye, Saint-Leu-la-Forêt, Sannois, and Taverny. The municipalities of Bessancourt and Frépillon are not affected.
The inquiry will take place over 31 days, from Monday, November 2nd, 2026, at 9 a.m. to Wednesday, December 2nd, 2026, at 12 p.m. The file will be accessible online via a dedicated digital register, as well as in paper format at the Val Parisis headquarters and in the relevant municipal offices.
Observations and proposals can be submitted directly on the secure digital register (https://www.registre-numerique.fr/zonage-assainissement-val-parisis), on the paper registers available, by email to zonage-assainissement-val-parisis@mail.registre-numerique.fr, or by postal mail to the investigating commissioner at the Val Parisis headquarters.
Ms. Emmanuelle Grange, investigating commissioner appointed by the Administrative Tribunal of Cergy-Pontoise, will also hold four public sessions: on Tuesday, November 10th (8:30 a.m. - 11:30 a.m.) at the Saint-Leu-la-Forêt Town Hall, on Thursday, November 19th (4:30 p.m. - 7:30 p.m.) at the Herblay-sur-Seine Town Hall, on Saturday, November 28th (8:30 a.m. - 11:30 a.m.) at the Franconville-la-Garenne Town Hall, and on Wednesday, December 2nd (9 a.m. - 12 p.m.) at the Val Parisis Agglomeration Community headquarters in Beauchamp.
Contributions will be accepted until Wednesday, December 2nd, 2026, at 12 p.m. After this deadline, no further observations will be considered. Following the inquiry, the investigating commissioner will prepare her report and reasoned conclusions, which will be made available to the public for one year before being submitted for approval by the competent authority.
