Innovation also takes place underground in the tech city of Eindhoven. A stone wool water-buffer system provides a sustainable solution to the flooding in the inner city.

This is the situation

The situation in Eindhoven is comparable to that in many Dutch (inner) cities:

  • Due to the changing climate, heavy peak showers mean that the sewer system is increasingly unable to carry away the water, resulting in flooding;
  • the city is highly compacted. Hard road surfaces are on the increase and the number of inhabitants, businesses and connections to the sewer system is increasing rapidly;
  • Since 2019, it is mandatory to integrate water storage into new projects in the private area in Eindhoven. An additional provision must be made for the collection and retention of up to 75 mm of rainwater within the planning area (an increase compared to the water policy prior to 2019);
  • According to current policy, a minimum of 25 mm and a maximum of 75 mm of water storage must be achieved for all new hard surfaces. The following applies: the greener the plan, the lower the specification in millimetres.

Looking for possibilities

Due to the increasing water load– and in particular the peak load– water storage must also be created under public spaces in Eindhoven. An effective solution is needed to avoid wet feet and floors.

The best (and most sustainable) solution for Eindhoven’s inner city is to retain the water in the area where it falls. Infiltration can sometimes also be a solution, as it also provides a solution in dry periods. Temporary water storage with delayed drainage is the most viable option, however.

The emphasis in Eindhoven is not on water retention. The city is situated in the water catchment area of the Dommel and the Aa, among others, and the groundwater level is high (often only 1 metre below ground level). Adding even more (rain) water to the groundwater could cause problems in the lowest areas. For this reason, temporary collection and delayed disposal via the rainwater sewer is preferred.

The advantage of the Rockflow stone wool system is that it is easy and flexible to install. Stone wool is light and easy to cut to size, so it's easy to adapt and fit into a limited space.

The solution

As a result of climate change, peak loads are becoming more common and may increase in severity. For the further development of water management in Eindhoven, it is therefore important to gain more experience with sustainable water-buffer solutions. A solution for both the implementation and the maintenance of the facilities is needed.

The choice fell on Rockflow as stone wool water buffer system for the renovation of the sewage system under the Hastelweg in Eindhoven. A water storage facility that can store and retain 60 mm of rainwater was created. This will mainly limit flooding above all on the lower part of the Hastelweg, in the direction of the adjacent Willemstraat.

The result

Underground water storage using the Rockflow system was almost the only solution for Eindhoven’s Hastelweg. This is a narrow street with a lot of trees and, in addition to car traffic, space is also required for cyclists and parking. The fact that the groundwater level is quite high also had to be taken into account.

The advantage of the Rockflow stone wool system is that it is easy and flexible to install. Stone wool is light and easy to cut to size, so it's easy to fit into (and adapt to) a limited space. With stone wool, you can easily cut out openings for pulling through cables, and plastic crates are no longer required. The stone wool elements do not leak and are not easily damaged.

This enables a climate-resistant and water-robust solution, in which sustainability is the top priority. The service life of a stone wool element is approximately 50 years. It is, of course, not entirely inconceivable that there will be changes to the situation above and below the ground during this period. This is also not a problem, because if more pipes are needed, for example, for optical fibres or electrics, these can simply be pulled through the existing elements.

With the Rockflow application, Eindhoven has taken a clear step forward with innovative curiosity, and has found a stable solution to ensure a future with as many dry feet and floors as possible.

Learn more about stone wool for linear attenuation and drainage systems:

Related Rockflow projects:

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Roy Janssen

Business Unit Director,