Rockflow water storage and infiltration system is installed under residential streets as a rainwater drain, commissioned by the municipality of Maasgouw (Limburg). The municipality previously installed Rockflow buffers beneath playgrounds and car parks with great success. The rainwater drain used has a total length of almost 3 kilometers. Rainwater from the roofs and streets is channelled via drainpipes and gutters to the underground water storage units, made from Rockflow elements. With an absorption capacity of 95%, the stone wool elements store the water quickly and release it gradually into the ground within 24 hours. Rockflow ensures that stormwater no longer enters the wastewater sewer, thereby preventing flooding in the event of extreme rainfall.
With Rockflow, Maasgouw municipality is opting for more effective water buffering and infiltration system than gravel or lava cases and crate systems offer. The innovative system stores twice as much water as lava and/or gravel. On top of that infiltration is faster since the bottom surface area of the buffer is available for water to percolate through. “Stone wool has such a high density (pore size less than 40 µm) that sand grains cannot infiltrate the system”, explains Lowie Eijkelhardt, civil technology project leader at Maasgouw Municipality. “The high absorption capacity of Rockflow also ensures that less material is required to achieve the intended buffer volume. Compared with lava cases this is a factor of more than 2. With Rockflow, less than half the amount of soil needs to be excavated.”