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Filtering runoff rainwater

For cleaner surface and groundwater

Runoff rainwater is not clean

Rainwater that falls is relatively clean. But once it ends up in the gutter, undesirable and harmful substances from roofs, cars, and streets are washed away with the water.

 

 

In a scientific study by Boogaard et al (2014), the concentrations of polluting substances in Dutch runoff rainwater were measured. The measured concentrations of many substances, including nutrients, copper and zinc, exceeded the Dutch standard for maximum allowable concentrations (MAC) for receiving waters. Microplastics are also becoming an increasing source of concern.

 

Rockflow cleans runoff water from roads and roofs

The natural environment and the quality of life in cities benefit from clean groundwater and surface water. That's why it's good to pre-purify runoff rainwater before it infiltrates into the ground. A buffer from ROCKWOOL Rainwater Systems consists of stone wool. This Rockflow package quickly absorbs the fallen rainwater, preventing urban floodings. And it retains a lot of pollution. Thus, the water that infiltrates into the ground or is discharged into surface water is much cleaner. The stone wool system itself can be cleaned in no time.

Stone wool captures pollution - with the power of stone

Stone wool is made from rock. The mineral fibres of stone are microscopically small. These fine fibres form a dense network with a large surface area, effectively filtering out pollution. Therefore, a Rockflow buffer not only captures water but also cleans it: The fibre structure effectively holds back suspended particles and common dissolved pollutants in urban stormwater. Our field results show an average reduction of 50% of the most common chemical pollutants in the captured run-off water:

 

Solid particles
0

Chemical pollutants
0

Through regular maintenance
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This is how Rockflow works as a filter

Stone wool fibre network

The dense network of mineral stone wool fibres effectively captures pollution.

The microscopically small fibres of Rockflow retain solid particles. Dissolved pollution particles attach to (small) solid particles and are also captured along with the particles. Additionally, dissolved pollution particles also bind to the mineral fibres themselves.

A Rockflow system is easy to maintain

Due to the filtering action of the stone wool, pollution accumulates over time. The polluting particles remain in the water channels of the Rockflow system. These channels can be easily cleaned. With regular maintenance, the system will continue to function well throughout its 50-year lifespan.

Download the maintenance guide
The water supply channels in Rockflow systems are easy to inspect and clean.
This can be done time and again using standard sewer cleaning equipment. After cleaning, the system is as good as new.

Eric Gallé

Vandervalk+degroot

Project in the spotlights: Cleaning 'first flush' on the RijnlandRoute

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Projects

An Innovative Solution for 'First Flush' Cleansing

In a low-lying part of the RijnlandRoute (N206) in South Holland (NL), Rockflow cleanses runoff rainwater. During a shower, the rainwater flows to a pump cellar. The ‘first flush’ is then passed through Rockflow stone wool elements and cleaned.

Want to know more about Rockflow?

Read on to learn more about how you can use Rockflow to prevent flooding and protect the natural water cycle. Get inspired in our community. Or read up on the design process.

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ROCKWOOL Rainwater Systems

Why Rockflow®?

All the advantages of Rockflow infiltration buffers at a glance.

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ROCKWOOL Rainwater Systems

About us

We believe in sponge cities. Cities that absorb and harvest valuable rain water, for safe and comfortable living conditions. And we believe in our Rockflow stone wool solutions for sustainable and future-proof water management. Together we can rethink urban water management.

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Maximum design freedom and quick installation

Designing and installing a Rockflow system

With our tools, you can quickly put together a suitable Rockflow design yourself.