Blue-green swales

Sustainable and safe infiltration systems for swales

If there is limited space, as is often the case in urban areas, swales may often need to be relatively deep to meet high rainwater storage requirements. This can create unsafe situations and make maintenance difficult. Rockflow stone wool elements can be used to make swales shallower, without losing capacity or the green appearance of the area.

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Rockflow increases the buffering capacity of swales

Capturing rainwater in urban areas is an important task. A sustainable and green method of doing this is to install a swale. As well as being a sensible way of capturing water, it also increases the green character of an area. If there is limited space, as is often the case in urban areas, swales may often need to be relatively deep to meet high rainwater storage requirements. This can create unsafe situations and make maintenance difficult. Rockflow stone wool elements can be used to make swales shallower, without losing capacity or the green appearance of the area.

What is a swale?

In the past, it was common for clean rainwater to be mixed with dirty waste water in the sewage system. This meant that relatively clean rainwater was unnecessarily transported to a water treatment plant. Nowadays it is becoming far more common to look for options for decoupling rainwater from the sewage system. Allowing rainwater infiltration not only prevents the waste of relatively clean water and overloading the sewer, but it is also good for groundwater levels, i.e. a sustainable solution.

One way of making it possible to allow water to infiltrate instead of being transported away in the sewage system is by using a swale: a ditch or trench with a water-permeable base. Swales can be situated in urban areas to capture excess water during heavy rainstorms. However, in practice, traditional swales do not always function as expected when they were installed.

The limitations of a traditional swale

When a swale functions correctly, it is an attractive and simple way of increasing water awareness in a residential area. But what happens if a swale does not work effectively, for instance if the soil below proves to be less permeable than expected? Or if a layer of silt builds up due to rotting plant material? This can reduce the infiltration capacity and create annoying problems for local residents such as problems with mosquitos and unpleasant smells due to rotting plants. There is also the risk that non-functioning swales can attract litter. Above all, a swale can be a danger to children playing outside and to animals, especially in a residential area.

Rockflow as the solution

Traditional swales usually consist of a dip containing a layer of earth planted with some vegetation. The swale captures rainwater and gradually releases it to the soil. However, because there are often space limitations, a swale has to be relatively deep so it can capture sufficient rainwater. This often makes the sides of the trench steep, requiring a special verge mower to maintain the swale. Without this essential maintenance, the swale no longer functions properly.

Rockflow, an infiltration system based on stone wool elements offers a solution for this. The stone wool elements absorb the water and discharge it gradually to the soil. This can be placed under the layer of soil and plants, creating more space for capturing water. Thanks to these stone wool elements, a swale using Rockflow stone wool is also less deep than the traditional sort. This simplifies both installation and maintenance. As the bank of the swale using Rockflow is less steep, the swale can be maintained using a ride-on lawnmower. The risk of accidents is also greatly reduced.

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Projects with swales:

Solution: Swale

Infiltrating and retaining water under a 'climate bioswale' in Zoeterwoude

Rockflow is used in more and more cities in the context of climate adaptation to prevent flooding. The system can also retain rainwater as a buffer for drier periods. These two functions - infiltration and retention - were recently combined in a single system for the first time. Thanks to a request from Zoeterwoude.

water management, case, construction, solution, lapinus

Solution: Swale

Rockflow offers a solution for the playing field in Heel

The playing field in Heel was located in a groundwater protection area, which presented a lot of challenges. Rockflow offered the solution here because a lot of storage can be created while you remain fairly close to ground level.

water management, sterplein, case, rockflow, heel, swale, lapinus

Solution: Swale

Rockflow offers a solution for swales in Sterplein

Rockflow tackled a too deep, too steep and difficult to maintain swale in Heel. Water that does not infiltrate quickly enough is led via the gully directly to the buffer from where it infiltrates into the subsoil.

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New possibilities

Nowadays, it is usual to look for opportunities to store water locally. Smart sustainable water management can therefore contribute to a healthy groundwater level. By upgrading a swale using Rockflow elements, we create new opportunities. A swale is then not only easier to maintain, but it also increases the buffering capacity as well as increasing the recreational possibilities of the plot for local residents.

A swale with Rockflow is flat and load-bearing, yet its water buffering function remains intact for many years. This creates the option of designing the swale to be used as a park, play area or green verge. Existing swales with maintenance problems can also be redesigned using this infiltration system. In this way, Rockflow opens up new possibilities for capturing excess rainwater in residential areas and thus helps combat local flooding.