First months of FLOT. pilot leave initiators satisfied

Text: Vincent Krijtenburg (translated from Dutch)

A bare sheet pile wall doesn't have to be a rusty eyesore. Since June, the Theodorus Haven in Bergen op Zoom has been experimenting with floating planters that should give the hard quay walls a natural look and contribute to biodiversity and water quality. Three months after the start of the pilot, the first impression is positive.

The planters, developed under the name FLOT to green sheet pile walls, were hung in the harbour as a pilot earlier this summer. The trial is an initiative of two companies from Bergen op Zoom, MH Poly Consultants & Engineers and Dutch Water Tech.

“About three months ago we used this location for a pilot, putting out around ten floating planters to see whether they would stay in place,” says Bard Louis, director of MH Poly Consultants & Engineers. “Large ships regularly pass through the Theodorus Haven, exposing the floating structures to waves and movement. It is precisely under these challenging conditions that FLOT has to prove itself in practice.”

“We also see a lot of new bank plants that we didn't plant there.”

Over the past three months, several inland vessels have moored here, with the unavoidable waves that mooring creates. Now Louis, sustainability adviser Merle Lincklaen Arriëns and soil and sediment adviser Puck Oomen climb into a canoe to inspect the planters. They check not only whether the structure is still firmly in place, but above all how the plants have developed.

According to Lincklaen Arriëns, this first inspection gives a positive picture. The plants have grown considerably and new species have also settled on their own. “It has grown a lot and we also see many new bank plants that we didn't originally plant there,” she says. As an example she mentions creeping yellowcress. A native knotweed that found its way into the planter from the surroundings was also spotted.

New plants settling spontaneously is exactly the kind of development the initiators want to see. The planters are meant to be more than a green decoration for the harbour. Plants above and below the water create extra living space for all kinds of animals.

Habitat under water

The inspection also shows what is happening under water. The plant roots grow from the planters into the water. According to the initiators, this creates extra habitat for aquatic life. The underwater structure plays a part too. The modules are held in place with a grass-concrete ballast block. This ballast provides stability, and also offers a place where underwater animals can settle.

“We want to keep this pilot going for at least a year.”

Although the first results are encouraging, Louis says it is too early to draw conclusions. The pilot has to run for at least a year. After all, the planters must survive not just a sunny summer, but also long-term exposure to ship waves and changing weather. “We want to keep this pilot going for at least a year to see what happens to our planters in the longer term,” says Louis.

For him, technical durability is an important yardstick. “I'll be very satisfied if they pass the test and show no structural damage after a year of intensive exposure to ship waves.”

That is why the steel cables and attachment points are also checked during the trip. So far there seems little reason for concern. “Everything is still hanging neatly in place. Nothing is loose, they aren't tilted. In fact, all the planters are still full. Yes, it looks good,” concludes Puck Oomen.

A small ecosystem

On board the canoe, the three imagine out loud a completely green sheet pile wall. According to the initiators, that would bring the greatest gain for biodiversity. Even so, they can already conclude that the current, relatively small intervention has an effect. The combination of plants, roots and the underwater structure already forms a small habitat.

Also watch the video: Floating planters to make the Theodorushaven greener

Direct link to ZuidWestTV (Dutch): https://www.zuidwestupdate.nl/nieuws/eerste-maanden-van-flot-pilot-stemmen-initiatiefnemers-tevreden/