To allow the revaluation of the Achères plain, I propose a revalorization of its spaces, using the wastewater treatment plan as a tool to create a new  and research landscape : marshes and wetlands that are in reduction throughout the French territory.

The plant choice makes it possible to propose a new forestry typology adapted to an exploitation thanks to the Prunus avium wood but also to a space of entertainment thanks to the other species which contributes to the diversity and the permanence of afforestation.

Two types of marshes are differentiated. The first marshes are sewage treatment areas. They are managed by a microtopography which allows to create diverse habitats according to the depth of the water, associated with a low vegetal stratum. The second marshes are wooded marshes allowing a last filter before the Seine. They are along the Seine and  restore the relationship between the forest of Saint Germain and the Seine and prepare the area for the next universal exhibition of 2025.