New pumping station at 'inaccessible' location

Commissioned by Hoogheemraadschap Hollands Noorderkwartier, Aannemingsbedrijf Schouls BV of Koudekerk aan den Rijn has started the construction of pumping station Nova Zembla in Ilpendam. For the seasoned specialist in building pumping stations technically not so much a challenge, were it not that the location is inaccessible for large equipment. The work is therefore carried out entirely from the water. And that does present the necessary challenges.

The Nova Zembla pumping station will soon replace the old Vurige Staart pumping station a little further down the polder. "This pumping station has reached the end of its technical lifespan," says Leen van Belen of Schouls. Nova Zembla will have a larger capacity than the old pumping station and will soon pump water directly from the polder to the storage basin. VOPO oppervlaktewaterbeheer, pump supplier and mechanical contractor, proposed Schouls to the Water Board for this project. "They had been commissioned by the Hoogheemraadschap Hollands Noorderkwartier to find a party for the civil part through a tender. And that makes that we are now both working on behalf of the water board, with us from Schouls as the main contractor taking care of the total coordination."

Deployment of pontoons

The location of the new pumping station was carefully chosen. "The biggest challenge of this location is accessibility," Leen acknowledges. "There is a bicycle path running along the quay, but it is not intended for heavy equipment. Initially the idea was to reach the site from the polder side, but that didn't work out due to the poor ground conditions." In fact, implementation is subject to a strict schedule: from October 2023 to March 2024 because of local flora and fauna. "Therefore, only one option remained: via water. But that had quite a few consequences. It is 500 meters by boat to get to the work site. We are used to working on the border between land and water, but usually the supply and removal of equipment and materials is done over land. That is not possible here. Everything is done from pontoons, which makes the project quite special and laborious. The logistics have to be in perfect order. Getting things wrong means sailing back and forth, and you'd rather not do that."

Construction pit walls 

Nova Zembla pumping station is a single-pump pumping station with an automatic duckweed cleaner from VOPO. "We started making the construction pit with steel sheet pile walls. These remain behind, as they also form the walls of the inflow and outflow construction at the same time. Then foundation piles were installed and the underwater concrete floor was poured. In this way we build the pumping station step by step from the storage basin side to the 2 meter lower polder side and back again. The polder side will then be completely finished, including the pump and piping from VOPO, before we start the completion of the storage basin side. Otherwise, we won't be able to reach it again." Schouls' work is still neatly on schedule, according to Leen. "Let's hope we don't have a lot of downtime due to the weather. After all, we are not working in the most favorable season. But the way things are going, we expect to be finished by March."

Schouls has tackled quite a few pumping stations for various water boards in recent years. "We have about three window contacts with water boards for new construction, maintenance and renovation of polder pumping stations, and are currently also building a new pumping station in Aalsmeer and in Den Hoorn." After 70 years in Leiden, Schouls recently moved from Leiden to a new and energy-neutral office in Koudekerk aan de Rijn. "With this we are set for the future."