Every day in Germany an area of approximately 90 football fields (around 75 hectares) is sealed due to urbanisation. The environmental consequences of this are significant as the whole water balance can be disrupted because stormwater can no longer naturally infiltrate into the ground. One of the major consequences of reduced natural infiltration is an increase in local flooding. The increased volumes of stormwater from urban developments are often simply diverted into existing stormwater and sewer systems and this frequently exceeds their capacities leading to local flooding. A lack of water for evaporation can also result in a hotter, drier climate in urban areas. This is known as Urban Heat Island Effect. In addition, pollutants from traffic and other anthropogenic activities in urban areas can compromise the quality of groundwater and receiving waters. This situation is expected to become even more problematic in future due to expected climate change. Research indicates that the intensity of the summer rainfall in Germany will increase substantially. Sustainable solutions for handling stormwater that more closely represent the natural water cycle are urgently required. Legislators have also recognized this situation. While the capacity of existing sewers in Germany can generally manage runoff from rainfall events of up to approximately 50 mm/h satisfactorily, permeable pavers can easily infiltrate more than 500 mm/h. However, permeable pavements are not utilised as often as they could be. One potential reason for the low utilisation rate of permeable paving systems is the stark industrial look that many of the traditional paving systems have. Traditional permeable paving systems often do not meet the design demands of landscape architects. Many also have important disadvantages like wide infiltration joints that can cause structural damage to the surface and are not practical for high heels or trolleys. The paper describes the development of a new permeable interlocking concrete paving system that has a maximum joint width of between 5 and 6 mm, which is in-line with German building regulations. The new pavers are very flexible and are not limited by shape, colours or surface finish. An innovative joint filling material was developed which has very high strength and pollutant removal capacity. The new system exceeds all stormwater treatment and infiltration requirements for general German technical approval. In addition, the new system has been field tested over a period of three years at three different sites in Germany and the Netherland. The cleaning process to renew the hydraulic permeability was also tested and optimized in the field studies. The paper presents results from the laboratory and field tests performed as part of the German approval process. It also gives recommendations for construction and maintenance of the new system.
36th International Association for Hydro-Environment Engineering and Research (IAHR) World Congress: Deltas of the Future and what happens upstream, Hague, Netherlands 28 June - 3 July 2015
Proceedings of the 36th International Association for Hydro-Environment Engineering and Research World Congress / pp.1-8