Due to the construction of new banks and dike reinforcement for the dike between Hoorn and Schardam, the water system in the polder behind pumping station Westerkogge in Scharwoude is changing. The existing inlet could no longer be used. Vopo Pompen- en Machinefabriek BV was engaged by the Alliantie Markermeerdijken to design and realize a new combination culvert. A truly unique example due to the many requirements of the Hoogheemraadschap Hollands Noorderkwartier.

Traditionally, Vopo Pumps (since 1904) focuses on the production of pumps for pumping surface water. Over the years, the company has grown into a leading player in the professional segment of the water industry, serving governments, district water boards, water boards, provinces, municipalities, engineering firms throughout the Netherlands. "We offer clients a one-stop shop for surface water techniques, such as (fish-friendly) pumps and pumping stations, inlets, duckweed cleaners, fish passages, weirs, electrical installations and piping," says Hans de Wit of Vopo Pumps.

Although Vopo still has the charm of a traditional family business and still mainly builds pumps with large capacity and low head, time has not stood still. In today's state-of-the-art factory with its own pump testing facility, the most ingenious pumps are built. "Many times pump installations are delivered turnkey complete with automation and automatic grate cleaners," says De Wit. "In many cases we are responsible for the design, production, assembly, installation and aftercare, as here on the Markermeer dikes. Because the existing inlet at the old former Westerkogge steam pumping station could no longer be used, an alternative was devised in the construction of a combination culvert. In addition to all life span and structural requirements, future user Hoogheemraadschap Hollands Noorderkwartier had laid down three important main requirements. The combination culvert must have an inlet capacity of at least 70 m3/min, enable fish migration to and from the Markermeer, and have a connection for emergency drainage of 100 m³.3/min."

"The above requirements make the new combination culvert a unique object," stated De Wit. "The design work started in 2018. The biggest challenge and effort in this phase was the exact alignment of all disciplines; civil, mechanical and electrical. Including all calculations and detailing the drawings. This to ensure the smooth running of the execution phase. The pipe of Ø 1,000 mm is equipped with two pieces of Ø 1,000 mm automatic butterfly valves, a decoy current pump, connection of Ø 800 mm for emergency drainage, various level measurements, an automatic grid cleaner and a complete control including pumping station computer to regulate all functions. After the design process, execution started in early 2020. Here the challenge was to plan all the work as well as possible in a short time frame and with limited space in the construction pit. But we managed to do that, too. In the summer of 2020, we successfully delivered the Westerkogge combination culvert."