Situated in the South of the Netherlands the village of Schimmert has experienced surface flooding regularly. With the heavy rainstorms, which seem to be much more frequent in recent years, the current sewer system cannot handle the sheer amount of water in such a short time.

On top of that the run-off water is very muddy with heavy loam from the surrounding hills. The resulting flooding has caused serious damage to resident’s cellars, garages and even houses as well as other water related problems. The problem was resolved in 2017 however, when Lapinus working together with the Royal HaskoningDHV engineering company, installed a Rockflow water management system beneath the adjacent schoolyard.

The rainwater running off the roofs of the neighbouring school, gymnasium and the playground is captured by Rockflow. In fact, the system is a subterranean buffer made from stone wool elements connected to gullies and wells. The installation captures around 500,000 litres (500 m3) water, which is then slowly discharged to the sewer system. This is equivalent to a ‘once-in-hundred-years’ rain shower. Drainage of the buffer to the sewer is delayed by 4-20 hours. After 24 hours the buffer is ready to take on the next big downpour.

In order to prevent the muddy water from blocking the buffer completely, a new stone wool based filter system was developed. This filter will take out any suspended particles before rainwater enters the stone wool, ensuring optimum operation with a minimum of maintenance.

Schimmert (Primary School), Nuth

Project location


Stone wool can absorb up to 95% of its weight in water


550.000 l water absorption in 30 minutes


Water released within 24 hours

water management, case, construction, solution, lapinus

Watch the video to see how Rockflow was applied under a schoolyard.