SUSTAINABLE URBAN

Rainwater retention and infiltration in urban areas is a sustainable alternative to traditional drainage systems such as combined or separate sewers. Infiltration can help in returning the urban water cycle to its pre-urbanized state. In Germany, all new developments are required by law to retain/infiltrate rainwater on site. Infiltration supports groundwater recharge, can decrease groundwater salinity, allows smaller diameters for sewers (resulting in cost reduction) and improves water quality of receiving waters because pollutants and high peak flow are effectively controlled. On the other hand, pollutants in runoff originating from domestic and industry emissions and traffic threaten soil and groundwater if they are not removed from runoff before it infiltrates into the ground. A wide variety of different infiltration systems exist and have been used and investigated in Germany since the beginning of the 1980s. Some systems, like permeable pavements, infiltrate the runoff directly, while others use surface storage facilities like swales or basins. A third group of systems uses underground storage spaces. Underground systems have advantages, but pollutants are not filtered as in systems with vegetated soil passage. For this reason, HydroCon has developed a new system that consists of