Storm water management in urban areas: Risks and case studies

Nowadays, in many cases, managed infiltration of runoff is practised as an alternative approach to storm water drainage. This practice supports the natural water cycle by the immediate reintroduction to the cycle of runoff components from different drainage areas. This increasingly widely used procedure has to be strictly assessed and controlled with the aim of soil and water protection. This paper presents some results of investigations with respect to the quality of topsoil in several infiltration troughs. A significant aspect to consider is whether long-term operation of the drainage systems could exhaust the buffer and filtration capacity of the soil. Investigations within specific infiltration projects showed that there is a high accumulation of substances in most materials used to construct roof drainage systems in the topsoil of the infiltration areas. Longterm operation can significantly reduce the cleaning effects of passage through the soil. Operational stability and reliable functioning of infiltration systems has to be guaranteed in the long-term. Therefore, the location, structure and operation of alternative storm water drainage systems have to meet some specific criteria.