This was a good functional solution, with the exception of one location - a swale on the Boslaan which served as a playing field. The original swale configuration with lava stone in the substrate appeared not to be working as anticipated. The soil into which the collected water had to be infiltrated appeared to be silted up, as a result of which water was not absorbed during wet periods. The playing field was regularly flooded and even had to be sealed off with fencing at certain times for safety reasons. This was an unacceptable situation, all the more because the playing field had been designated as an important social area by the neighbourhood steering group at the start of the project. A solution was therefore required which combined the functions of playing field and water storage in this location.
Daniëlla Houben, civil policy worker at the local authority: “We cannot reach the desired depth for infiltration at this location because it is a groundwater protection area in which we are only permitted to work a maximum of three metres below ground level. This restricted us somewhat, as we had to be able to dispose of 500 m3 water. Together with Ria Smits, my colleague from sewer maintance, I began to investigate the options. Ultimately, Rockflow® appeared to be a workable solution, as it provides a great deal of storage, you can stay really close to ground level and it is easy to configure and adapt. It is also maintenance-friendly and not usually susceptible to blockages”. The last point was also important as the site was adjacent to the edge of a wooded area, where there was a great deal of sand and leaf debris.
Rockflow is a water management system which can buffer large volumes of rainwater in urban areas quickly and effectively. The innovative system is used beneath constructed surfaces such as squares, roads, streets and industrial estates that have to cope with severe flooding during heavy rainfall. The system is also used for the buffering and disposal of rainwater in swales. Rockflow consists of slim (standard element 100 x 120 x 15 cm), light (less than 20 kg) stone wool elements, which can absorb 95% of their volume in rainwater. From there the water can infiltrate into the ground layer or be discharged to the sewer system or surface water.
Heel (Reutsberg), Maasgouw