A Cruyff Court with a subsurface waterbuffer was opened today on the Spartaplein square in Rotterdam. The event was held in tandem with a big neighbourhood party, which had the waterbuffer as one of its themes. More and more cities are confronting the question of how to deal with heavy downpours and drought. A broad consortium of Water Authorities, municipalities, companies and knowledge institutes, working within the TKI Water Technology programme, are looking at the Urban Waterbuffer for a solution. This unique, innovative concept aims to retain the rainwater for longer in the city’s subsurface, thereby preventing flooding and making extra water available in times of drought. The first Urban Waterbuffer was opened on 19 April 2018 in Rheden.
A subsurface waterbuffer, in which rainwater is harvested and stored in the subsurface for later use, has been installed at the Spartaplein square in Rotterdam. The water storage under the Cruyff Court can harvest circa 30 millimetres of rainfall from about 4 hectares of streets, roofs and squares, thereby reducing the risk of street flooding. The harvested rainwater is then pre-treated in a compact vegetation bed, containing a natural sand filter with reeds and sedges. The pre-treated water is then stored 20-meters deep in a sand aquifer via a water well. This water can subsequently be pumped up to be used for watering the Sparta Stadium’s grass pitch, for cooling via the vegetation bed, and for supplying water for recreation on the square. A completely circular system is created, in which the neighbourhood residents can keep their feet dry and rainwater is recycled. Active communication methods are also being used to increase water awareness in the neighbourhood. Bert de Doelder, an engineer and water-project advisor with the municipality of Rotterdam, sees further opportunities for the concept. ‘We already have advanced plans for definitely two, and possibly four, other sites where we want to infiltrate rainwater into the deep subsurface,’ he says.
The first Urban Waterbuffer was opened in April 2018 on the edge of the Veluwe in Rheden. Whenever heavy downpours occur, large volumes of water flow from the slopes of the Veluwezoom to lower-lying roads and the Hotel de Roskam. This regularly causes street flooding. With the Urban Waterbuffer, the water is collected, the sand and leaves it contains removed in various ways, and it is then infiltrated to a depth of 10 meters via (for the time being) three water wells. In this way, using minimum space, the rainwater is quickly discharged and the groundwater is recharged. Roel Moed, policy-worker at the municipality of Rheden notes that ‘it is interesting to observe the workings of the various pre-treatment methods, since it helps us choose a suitable approach for the system’s maintenance in the future. We’ve already had a few very heavy downpours, so we have a reasonable sense of the system’s capacity. We’ll continue testing the three wells in the upcoming year. Afterwards, we will probably install a few more wells in Rheden so that we can really discharge the volumes of water we want.’
Over the next year, the Urban Waterbuffers in Rheden and in Rotterdam will both be monitored to assess the effectiveness of the pre-treatment and build up practical experience. The results will be incorporated into a handbook.