Foundation giants join forces

The widening and sunken construction of the A9 between Badhoevedorp and Holendrecht, carried out by VeenIX on behalf of the Directorate-General for Public Works and Water Management (Rijkswaterstaat), involves a route of more than 11 kilometers. Given the scope of the project, Gebr. van 't Hek and Voorbij Funderingstechniek have joined forces. Under the name TerraFirmA9, both foundation giants have been active since 2021 with a "large number" of scaffolds currently on the job.

Already in the calculation phase we sought each other out to tackle the project together, begins Sander Poot, project leader at Gebr. van 't Hek. "The work is of such magnitude that it is impossible to take it on alone and serve other clients in addition. No one can do this alone." Erik Sandifort, project manager at Voorbij Funderingstechniek, can also attest to this and gives an indication of the sheer volumes. "To date, we have already installed 20,000 tons of sheet piling, 400 tubular piles and 3,300 temporary and permanent anchors."

Preparatory work

Between 2021 and 2022, TerraFirmA9 made the earth retaining walls for the bypass, the temporary diversion of the A9. "We spent about a year and a half doing that," Sandifort says. "For example, we set and anchored various temporary and permanent earth retaining walls, including on-site welding. We also drilled plenty of piles for a number of auxiliary bridges, such as the bridge over Keizer Karelplein, the longest temporary bridge in the Netherlands at the moment. We also pulled and injected old sheet piling and seepage barriers to restore a watertight layer and removed some old foundations here and there from demolished structures." Actually, we've only started putting in the earthworks for the new A9 since this year, Poot acknowledges. "And especially around the center of Amstelveen for the construction of the sunken position. Here VeenIX is first building the north side and in two years the south side. That means a lot of sheet pile walls and anchors for us, both temporary and permanent."

Largest foundation task in the Netherlands

Technically challenging is not so much the project, according to both men. "The challenge lies mainly in the enormous quantities that have to be applied in a short period of time, combined with organizing the logistics," says Poot. "In terms of foundation task, it is the largest project currently under construction in the Netherlands. On top of that, the project is in a state of enormous flux, which sometimes results in a changed schedule. It's up to us to manage that by a sophisticated deployment of people and equipment." The cooperation between the two foundation companies in TerraFirmA9 runs like a well-oiled machine. Sandifort: "In our world, it's quite special to form a combination with a competitor. There is absolutely no question of competition in the combination. The cooperation is really great. We are working together as colleagues on this mega project." Currently, TerraFirmA9 is active on the project with over twenty racks.