Joining forces on sustainability: Wavin and the city of Rotterdam in action.

Sewer tender in Rotterdam

With one hundred kilometers of sewers in need of replacement every year, Rotterdam is among the largest consumers of sewer pipes, manholes and drainage systems in the Netherlands. The municipality of Rotterdam has considerable sustainability ambitions; Rotterdam will have to transition to a fully circular economy by 2050. In addition, Rotterdam wants to designate the inner city as a zero emission zone starting in 2025, which fits in with the government's ambition for the construction and infrastructure sector to achieve zero emissions by 2030. To that end, zero emission zones will be established in many cities starting in 2025. New vehicles will only be allowed in these zones if they have zero emissions. By 2030, all vehicles in zero emission zones must be completely emissions-free.

"The tender for the replacement was exceptional: only twenty percent of the award was based on price, although there was a price ceiling in place. Environmental cost (ECI) was good for thirty percent, emissions-free transport made up another thirty percent and the remaining twenty percent was based on circularity. Basically, eighty percent of the tender was determined by sustainability," says Thijs Kroese, Sales Director Civil & Infra at Wavin. The collaboration between Wavin and the City of Rotterdam will last for six years, with an evaluation every two years.

Circular

The circularity index was an important part of the award criteria; what percentage of the equipment is recycled material and what percentage can be recycled? "We make plastic pipe systems out of PE, PP and PVC. PVC pipes already largely consist of recycled material. Technically speaking, it is not a problem for PE and PP either, but the applicable standards for drinking water pipes, for example, do not yet allow the addition of recycled material. PE casing pipes, on the other hand, are allowed to be circular. We also make PP street gullies and infiltration crates from fully recycled materials, which we use in Rotterdam. Finally, clients can opt to deviate from private standards and use a circular pipe instead," Kroese says.

For PVC, the percentage of recycled material is currently at least forty percent across the product range. "We can technically reach 100 percent—the greatest challenge lies in obtaining enough old pipes," says Tristan van de Pavert, Marketing Director for Northwestern Europe at Wavin Group. "Hard plastics are tremendously durable; you can take a plastic pipe out of the ground after sixty years, and it will hardly have aged. The material is inert, so it does not absorb or leach anything. Underground pipes and ducts are also unaffected by UV radiation. There is no reason you couldn’t reuse the pipes after a hundred years if you work smart and use modular sizes."

Most of the sewer work in Rotterdam is due to subsidence, changes in connections and modernization. "The biggest risk with PVC pipes is not the aging of the material, but pipe deformation caused by soil pressure,” says Kroese. “A pipe that has become oval or bent over the years will be hard to use in a new situation. The only option left in that case is recycling. We want to relocate as many plastic sewer pipes as possible instead of replacing them; we remove the pipes from the ground and reinstall them at the correct depth and location. Basically, we dig up sewage pipes, inspect them, clean them and put them back with new seals. We are working with contractors and the municipality of Rotterdam to find suitable pilot locations to test the process. Sustainability is high on Wavin’s agenda. An increase in the use of recycled materials is just one focus point, we are also working with local authorities to explore solutions that improve climate resilience—things like smart rainwater harvesting, temporary storage and reuse in times of drought. Urban greening (e.g. solutions to combat heat stress) is also on Wavin’s agenda."

Zero emissions

Another important asset in this sustainable procurement process is the emissions-free transport of new pipes, infiltration crates and street gullies to the downtown area. HUB010 offers a solution in that regard; with the hub on the outskirts of Rotterdam, the last-mile delivery can be completed with zero emission (100% electric) vehicles. "From our location, we can consolidate, temporarily store or transfer loads to one of Vlot Logistics' zero emission vehicles."

The first products have already been delivered using zero emission vehicles. "The project is also a great pilot for us to gain experience. Wavin already had plans for zero emission transport, but these would still have taken several years to bring to fruition for economic reasons. The municipality of Rotterdam’s tender specifications set the conditions necessary to accelerate the transition, thus creating an opportunity that arrived at the right time for us."

Novelties in the ground

In addition to replacing and improving the Rotterdam sewers, Wavin will also supply several novelties, such as the Wavin TreeTank® and Wavin Tegra street gully.

Wavin TreeTank

Wavin's new TreeTank® promotes tree growth and prevents tree roots from damaging the road surface. A hole is dug and filled with plastic crates at the site where the tree will be planted. The tree is planted in the center, and the rest is filled with nutrient-rich soil for the tree, known as substrate. The tree is anchored to stabilize it. In addition to nutrition, trees need water, oxygen and soil life to grow. The TreeTank provides optimal growth conditions. The blue Wavin TreeTank® crates have strong sidewalls and lids, feature the largest open spaces and passages and offer the highest load capacity in terms of traffic class. The crates allow the soil around the system to be compacted according to the applicable standards; cables and pipes can easily be run through the crates and cars can be parked above the crates without a problem. The system provides the optimal environment for growth, protecting the tree from the pressure of the road surface while also protecting the road surface from the tree. Due to the excellent conditions in the TreeTank, the tree will not have to search for water and nutrients, thus preventing root pressure.

Wavin Tegra street gully

The Tegra street gully is made of one hundred percent post-consumer recycled plastic and is fully recyclable. The 360˚ water trap and self-cleaning filter ensure optimal surface water drainage. The smart design captures leaves and other debris to keep them from ending up in the underlying system or the environment. The bowl-shaped bottom and smooth plastic ensure that the sludge centers itself in the sand trap, preventing dirt from getting stuck in the edges or corners and leaving no obstacles for the vacuum trucks. This sustainably manufactured storm drain offers the best filtration system and the largest dirt collection capacity; its low weight makes it is the easiest to install and the best to maintain.

Video Rotterdam and Wavin

Thanks for reading the story! Now go ahead and watch the video that will give you an even better idea of the challenges ahead for the city of Rotterdam.

This article was written by Frank de Groot.