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Within the Markermeerdijken Alliance, a consortium led by Boskalis Nederland is working on behalf of the Holland Noorderkwartier Water Authority (HHNK) to reinforce approximately 33 kilometers of dike between Hoorn and Durgerdam. The aim of the work, which started in 2015, is to guarantee the safety of the people who live and work in the area for the next 50 years. As an all-round foundation specialist, Gebr. van ’t Hek is making a significant contribution to this unique custom project. It is doing so together with Linden Staalbouw and Hektec, partners that also belong to the multidisciplinary Van ’t Hek Group, the total provider in the field of foundation techniques.
The reinforcement of the monumental Markermeer dikes, which are located on peat soil, is a perfect fit for Gebr. van ’t Hek, which operates from Zuidoostbeemster. “As an all-round foundation company, we have a preference for working on the water, along the railroad tracks, and in inner cities,” says managing director Bas de Lange on behalf of the company, which was founded in 1945. “We also specialize in the construction of complete building pits and occupy a leading market position when it comes to vibration-free and low-noise techniques. In short, we have exceptionally broad expertise that will serve us well on the shores of the Markermeer.”
From the moment Gebr. van ’t Hek became involved in the project in 2019, the company carried out various activities. First, three outer dike unloading walls were constructed between Hoorn and Durgerdam. These temporary work areas, consisting of sheet pile walls filled with sand and stones, will also be removed by Gebr. van ’t Hek once the project is completed. “The unloading walls are used to transport the necessary materials and equipment by ship. This mainly involves sand and clay,” explains project manager Dennis Jonges. “We have also constructed a dike breach, including foundations, at two locations using sheet piling. At the end of 2019, we started building such a facility near the Westerkogge pumping station, which will ultimately allow water to be pumped from the polder into the Markermeer.”
Installing a solid sheet pile wall is also the solution when the rejected dikes cannot be reinforced with soil fill. The installation of the first sheet pile wall construction is planned for later this year at Uitdam. It is a project that Gebr. van ’t Hek will carry out in close collaboration with its sister companies Linden Staalbouw (welding and construction work) and engineering firm Hektec (calculation of the sheet pile wall construction). “Immediately after the construction industry's summer break, we will first carry out a trial 35-meter-long structural dike reinforcement,” says De Lange. “If that is successful, we will start the full dike reinforcement in January next year. Specifically, this involves 550 meters of sheet piling, which will reinforce the entire village on the Markermeer side. We may repeat similar projects in other places. Whatever the future may hold, one thing is certain. We have the right people and resources in-house to carry out this job and make this part of North Holland a lot safer again.”
