Like any new construction, Calais Port 2015 must comply with strict standards in terms of quality of stormwater discharge and sanitation. The port extension was thus divided into 5 watersheds, and each outlet to the sea ends with a buried RTU (Rainwater Treatment Unit), before discharge into the sea.
When there is a major storm or rainfall, the collected water flows over the coated surfaces, cleaning and removing any pollutant (trace hydrocarbons) and fines carried by the winds. The Rainwater Treatment Unit (RTU) thus consists of a silt storage (to retain suspended solids) and a hydrocarbon separator, all adapted to the surface area concerned, which is very important for each basin.
These structures will have to be monitored and maintained throughout their life cycle
to guarantee the discharge quality criteria required by the environmental authority.