Van Aalsburg and DEME strengthen dike around Marken with smart hydraulic engineering

Marken is getting a future-proof dike that should offer residents protection from high water for the next fifty years. The dike reinforcement will combine modern hydraulic engineering techniques with traditional knowledge and materials. Van Aalsburg is working closely with the main contractor, Combinatie Hof op Marken.

Collaborating smartly on a complex task

Parts of the current dike around Marken are too low or no longer meet safety standards. Rijkswaterstaat awarded the contract for dike reinforcement to the Hof op Marken combination (DEME Environmental and JLD International). Van Aalsburg BV was intensively involved from the beginning.

"Marken is surrounded by very shallow water," explains Dick van Aalsburg. "With ordinary large equipment you get stuck there. We have specialized shallow-water equipment, a pusher with a paddle drive that can maneuver even at a depth of one meter."

Trial courses as preparation

Before the design became final, the combination laid two test sections of 100 x 9 meters in 2022, installing 14 layers of cots (total height of 130 cm), to see if the conceived construction method worked in practice. In these, Van Aalsburg provided a light version of a laydown, constructed from willows and cots.

"The peaty subsoil can't take much pressure, so if you put stones on it they sink," Van Aalsburg explains. "With such a layer or sinker, you can distribute the pressure much better, achieve good stability and keep the sand in place. Based on that pilot, the design was further refined."

Layer by layer building the dike

The dike will be built in phases. Combination Hof op Marken is spraying up the sand in rings around Marken, layer by layer. Where necessary, Van Aalsburg helps with special swamp cranes to get everything in place. Vertical drainage drains the water to accelerate the settlement of the sand. "After each layer, we apply a temporary sinker on the outside," Van Aalsburg says. "That prevents erosion from wave action. The stones for this come from the inner slope of the old dike. Once the dike is at height, we'll remove the temporary zinc pieces and lay a final, heavier zinc piece with a sturdy non-woven and PP fabric with loops and paving on top. We have already made a test piece of 3,000 m2 of final construction to see how it holds up."

Close cooperation

The cooperation between Van Aalsburg and DEME extends beyond dike reinforcement on Marken. "For example, we installed an amphibian screen along the bicycle path near this dike for Combinatie Hof on Marken," says Van Aalsburg. "And internationally we helped DEME's parent company in the Ivory Coast: there we delivered fifty containers full of willow branches and cradles to make zinc pieces and taught them on site how to tie them themselves. Since then, they have continued to process it there themselves." Assignments like these underscore Van Aalsburg's broad commitment, from local challenges to customization on the other side of the world.