Artist impression Wavin Q-Bic Plus tree tanks

Green Cities – Wavin supplies plastic tree tanks in Hasselt for trees to grow and flourish

More than half the world’s population are living in cities. As such, city dwellers are being exposed to a number of environmental issues due to climate change, such as heat stress and air purification. Trees are essential for mitigating many of these problems. They produce oxygen, improve air quality, provide shade, and reduce the effects of global warming. And they contribute to the health and well-being of the people who live and work in these cities. 

In the Belgian city of Hasselt, a new neighborhood is under construction: Quartier Bleu. And they wanted to invest in sustainability of their tree canopy. Wavin provided a unique and versatile solution.

The Challenge: Cost-effective and sustainable tree growth

Just like many other cities, the city of Hasselt wants to add more greenery to the streets. However, while there are so many sustainable benefits to planting trees in cities, trees are vulnerable and they are also a big investment – expensive to maintain, to grow and stay healthy. But planting trees in the traditional way – immediately adjacent to roads, pavements and engineered structures – causes trees to struggle to grow, to die, or to have their roots push through the pavement and ruin sidewalks and roads.


The Solution: The Wavin Q-Bic Plus alternative solution for tree root protection

Namely, the Wavin Tree Tank. Together with the Hasselt’s contractor Willemen, Wavin worked on a plastic solution to provide Q-Bic Plus infiltration units to protect the tree roots and allow large trees to grow – creating a green city.

We are responsible for the exterior construction of this project: from drains and pavements to plants and street furniture. Since we had been working with Wavin for some time, it made sense for us to look together for a solution for larger green areas in the urban area. That became the Q-Bic Plus Tree Tank.
Rob Eyckens , Willemen

How does the Q-Bic Plus Tree Tank work?

At the location where the tree will be planted, a hollow space is created in which plastic crates are placed. The tree is planted in the middle and the rest is filled with substrate. To stabilize the tree, it is anchored in place. In addition to substrate, water and air are also crucial for the tree to grow. Harvested rainwater can be introduced into the root volume via additional pipes.

The blue crates of the tree tank have strong side walls and lids. These ensure that the soil around the system can be compacted in accordance with the applicable standards. In this way, it is not only an ideal environment for the tree to grow, but also the pavement around the tree remains in good condition and there is no root imprint.

With the installation plan, the Q-Bic Plus Tree Tank can be quickly mounted, placed and disassembled. It is a flexible system. So, when cables and pipes have to be laid in the ground at a later stage, the tree tank can be easily excavated and opened up. Additionally, the stability calculation provides certainty about the long-term sustainability of the system.

After the trees are planted

Once the trees are planted, the soil gets replenished and compacted. After that, the pavement is laid. The Q-Bic Plus Tree Tanks made it possible for the municipality of Hasselt to plant 86 large trees in the Quartier Bleu district. To date, 2500 cubic meters of material for the tree tanks has now been delivered and assembled. The project, which commenced in May 2019 is now complete. It was a big project for Wavin and demonstrated the value of long-term relationships with stakeholders (like Willemen) of the Wavin Belgium team – combined with ‘out-of-the-box’ solution thinking.

The future of Wavin Tree Tanks

This unique project represented Wavin’s commitment to being a leader in the movement to build a sustainable future for urban environments. The Municipality of Hasselt in Belgium are the first to have placed an order – on a new and unique green solution to an old, lingering problem. Many European countries are seeking sustainable tree pit solutions for their urban areas, and Wavin hopes to promote this system in cities across Europe. Which city will be next? Stay tuned.

Project: New-build project Quartier Bleu

Location: Municipality of Hasselt (Belgium)

Built area: Wavin supplied a total of 2500 cubic meters of Q-Bic Plus units for the tree tanks – so 86 trees can grow.

Contractor: Willemen