Surfing in downtown Rotterdam

RIF010: feat of construction engineering

A bold plan to create a surfing pool in the middle of Rotterdam's inner city will soon be crowned. On July 6, the official opening of RIF010, a 130-meter-long and 21-meter-wide wave pool where enthusiasts can surf, canoe, dive and bike on pumptracks, is planned. A feat of construction engineering for such an inner-city location, especially since the 1942 wharves founded on wooden piles and trees had to remain intact.

It all started in 2014. An ideas competition of the Rotterdam Stadsinitiatief, set up to make the city center more attractive, was won that year by RIF010. The idea was to build a surfing course in the Steigergracht canal. Initiator Edwin van Vliegen saw in the idea of a wavepool a way to breathe new life into the rather unattractive canal between the Markthal and Beurstraverse. With the help of Mobilis/TBI, he developed this idea; only it took until 2019 until everything was procedurally complete. Add Covid-19 to that and eventually the first sheet pile walls went into the ground only in April 2023. In the meantime, prices had risen through the ceiling and construction could only start after adjusting the design and additional (private) financing. 

Wooden poles

RIF010 is an exceptional project, even for Ruud Arkesteijn, Underground Construction Specialist at Mobilis TBI. "Wave pools have existed in the world for some time, but not in an inner-city canal in a construction pit," he says. "We are building a wave pool in the Steigergracht, a wave generator on the side of the Market Hall and a pavilion with catering facilities near the Wezenbrug. What makes the construction extra complex is the fact that around the canal are masonry quay walls founded on wooden piles that are also heavily braced. Furthermore, the wave pool had to fit within the canal and be structurally separate from the quays. And you obviously want as wide a pool as possible to get the best surfing experience. It was finally decided to make a closed U-bucket with sheet pile walls in the moat. The combination of a wet construction pit and a floor of steel fiber reinforced underwater concrete (SVOWB) proved to be the best solution. This made it possible to achieve sufficient back pressure during construction with a slightly raised water level to control deformation of the sheet piling, the quays and the old pile foundation. With a slight bracing of the sheet piles, the wooden piles could be spared and as much width as possible was left for the wave pool."

Slim floor

In April last year, work began on the all-round installation of sheet piling in the Steigergracht, the drilling of piles for the floor, the application of a gravel layer and the pouring of the 2,250 m2 floor with underwater concrete (see articles below). "In fact, three types of floors were used," Arkesteijn specifies. "Under the pavilion, on top of the temporary unreinforced underwater concrete floor is a final reinforced floor. Under the deepest part of the basin, the pump cellar and the wave chambers, there is an SVOWB with a poured floor because of the waterproofing requirements and the higher load. Civil engineering-wise, the SVOWB in the rest of the basin is most unusual. Underwater concrete is traditionally used to keep a construction pit dry temporarily, here the floor is given a permanent function in the final phase. Draft design rules from a new CROW/CUR design guideline aimed at permanent use of SVOWB floors were used for this purpose. This was possible in part because the surf pool is not subject to a waterproofing requirement. The steel fiber reinforcement made this possible and also allowed the thickness to be limited to only 750 mm."

5% slope

After pumping the construction pit dry, construction could begin on the concrete wave basement, the wood-clad pavilion and the concrete lining of the wave pool. For the formation of the reef, a sand layer is poured on top of the underwater concrete floor that makes the final elevation. Arkesteijn: "The underwater concrete floor has a maximum slope of 5%. With a layer of stabilized sand and the profiling floor applied to it, we make height differences with slopes up to 20%. This is all calculated in Surfloch's design."

Surroundings

Environmental management always plays an important role in such inner-city works. "Especially in an extensive civil engineering project like RIF010," Arkesteijn emphasizes. "You are working with pontoons and a lot of large equipment and all that has to be brought in and placed in the canal and eventually out again. That is well prepared and worked out with all the partners in the construction team. The other day, when the eight blowers for the wave installation were hoisted in, it was clear to see how closely everything works. Furthermore, work was constantly done with low-vibration equipment, with the quays and surrounding buildings being constantly monitored for deformation."

Early this summer, the first wave will roll through the wave pool. "Then Rotterdam and Mobilis will have a great calling card to show for it," Arkesteijn concludes.