The effluent collection system in the municipality of Lamentin is currently connected to four wastewater treatment plants: Mahogany, Gaigneron, Long-Pré, Pelletier. The Long Pré wastewater treatment plant dates from the 1970s. It has a fragile structure and does not have a sludge treatment line in accordance with the regulations. ODYSSI wants to remove it and transfer wastewater from this plant to Gaigneron for treatment. This project is part of the CACEM Sanitation Master Plan and aims to reduce pollution points related to wastewater treatment. The following infrastructure structures shall be constructed: — construction of a back-up station in Long Pré – establishment of a sewerage network between the new discharge station of Long Pré and that of Mahault. The boundaries of the project covered by this report are, upstream of the mahogany and Long Pré wastewater treatment plants and downstream, the Petit Manoir discharge station. This new equipment (backload station or networks) will also have to meet the needs for increased collection linked to the increase of the population defined in the overall sanitation scheme.