Green potential of a constructed wetland with reed bed filters on a 172 ha urban project near Reims (France). Project evolution analysis

A 172 ha town planning project has been developed near Reims (France) for the last five years. For one of the catchments of this area (72ha) a 15 000 m3 detention pond is being built, in a difficult hydrogeological context since ground water level may rise up to the natural ground. The characteristics of this detention pond have drastically changed along the design process: the first hypothesis were based upon a deep concrete tank, but a constructed wetland has finally been chosen. This paper deals with the constructed wetland characteristics itself on the ecological point of view (deepness, shape...). It also points the design process that allowed such an evolution, thanks to both the designer proposals and the public authority requirements