The French airport of Paris Charles de Gaulle was recently subjected to frequent snow events. During such events, airplanes are treated with particular fluids that avoid the icing process or help for removing the ice already installed on the planes. These fluids are made with chemical components such as propylene glycol that are considered as pollutants. Because of the pollution constraints given by the French law, the airport should treat the runoff water so that released water from the platform in the environment meets the minimum pollutant level required.
Up to now, the strategy was to store all the water and treat them before getting them back to the environment. However, the last heavy winters showed the limit of such a strategy since the storage basins were almost full and close to overflow. A study was then conducted in order to define the best strategy to implement so that the airport is able to meet the pollution constraints by optimizing and improving the existing hydraulics components of the platform. An innovative dynamical strategy was then proposed.
Since the first flows are the most polluted one, the methodology of this innovative study was based on the development of an appropriate stormwater model that can take into account the pollution dynamics, the hydrological components such as the snowmelt and the implementation of appropriate dynamical regulation rules. PCSWMM 2D, that is a particular user friendly and complete hydraulic modeling software, was used to represent the entire hydraulic system, including the snow melt phenomenon as well as the regulation rules that could be implemented in existing or new retention basins.
Since a previous PCSWMM model was initially developed for particular return period storm events, it has first to be recalibrated for continuous winter periods modelling that include snowmelt. Then, a large number of scenarios, based on various temperature and flow rules were realized. Besides a better understanding the dynamic behavior of the stormwater and pollutants flows during winter, the model permitted to determine the required retention basins capacities and flow regulation constraints to implement. A real time approach is also under consideration in order to help the people in charge of the platform management to operate their hydraulic works in real time during crisis periods.