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Six pump blocks, each 9 meters high, ensure that the pumping stations at Den Oever can still discharge water from the IJsselmeer into the Wadden Sea during exceptionally high water levels. Waco, a Concrete Valley company, is responsible for the production and delivery of the prefab pump blocks, also known as snail shells. A complex job where precision is of great importance.
In order to discharge more water from the IJsselmeer into the Wadden Sea, two additional sluices will be built as well as two pump pumping stations. In this way, more water can be drained from the IJsselmeer into the Wadden Sea if necessary. The two additional pump pumping stations each have three pumps that can work together against gravity. "For the total of six new pumps, we are providing the pump blocks," said Maarten Kanters, technical director at Waco. "The pump blocks are 9 meters high and have a diameter of 4-5 meters. The efficiency of these pumps is 70 percent, which is exceptionally high for the application and the design requirements set."
Together, the pumps can move 235,000 liters of water per second from the IJsselmeer to the Wadden Sea. To guarantee this pumping capacity, the pump blocks must meet the highest requirements. They are therefore completely custom designed and made. The snail shells themselves are made up of nine elements. The feed mouth consists of four prefabricated elements. One pump assembly thus consists of thirteen elements. The reinforcement is bent in a special way, special molds have also been developed for this using 3D models. This is to check and compare with the theoretical models. The snail shells each have a complex round shape with minimal tolerance. "It is precision work par excellence, because the shape is essential for an optimal flow rate and degree of water suction. By collaborating on the outer shape, where we made the walls thinner, we were able to achieve a large weight saving."
Due to the specific project requirements arising from the water quality, salt water from the Wadden Sea and fresh water from the IJsselmeer, the concrete mixture was carefully considered in advance. The concrete mixture was specially designed and tested in which the temperature development was of great importance. Also, no limestone (flour) was used due to its possible corrosion by the seawater.
It is Waco's experience with complex products that led the company to be called in for this assignment. "Our company dates back to 1888, we can build on over 130 years of experience and knowledge. Our motto is not for nothing 'You dream it, we'll make it'. In an assignment like this, creativity, innovation, quality and solution-oriented thinking, come together. The great thing for us about this project is the combination of serial work and specialism in complex concrete elements."
