Rijkswaterstaat, together with Allseas, has developed an innovative collection system that collects both floating litter and waste up to a metre under the surface. The system, Catchy, has been put into use in the Vijfsluizerhaven. The system prevents macro and microplastics from flowing into the protected nature reserve and out into the North Sea.

Catchy is supported by the EU LIFE-Programme and although GreenWIN is not part of the LIFE-programme, Catchy is a great example and inspiration for integrating sustainability goals in projects for hydraulic structures and therefore Rijkswaterstaat wants to share this through the Green WIN website and social media platforms.

Catchy collects litter 24 hours a day, 7 days a week – both floating waste and underwater waste. The system works entirely on wind and current, and is not limited by weather conditions. Thanks to its robust design, Catchy can withstand wind force 10, waves up to 1.5 metres, flow velocities of 0.5 metres per second and tidal variations of 4 metres. “The non-return flap, at the front of the system, ensures that the collected waste cannot flow back out of the collection cage,” says Jeroen Hagelstein of Allseas.

Catchy has two floating booms (one of 12 metres and one of 200 metres) fitted with an underwater skirt at the bottom. As a result, both floating waste and waste up to 1 metre below the surface are guided into the collection cage. Jeroen Hagelstein: “In Vijfsluizerhaven, this is deep enough to collect the largest waste flows. This also gives enough space for fish to easily swim underneath the skirts.”

Installed as a pilot in the Vijfsluizerhaven on the Nieuwe Maas, the system will remain in place until June 2021. The results of the pilot are expected in June 2021.

“Due to the effect of currents and strong winds from the southwest, a lot of litter is pushed towards the Vijfsluizerhaven and the nature reserve behind it,” explains Wijnand Kooring (Project Manager, Rijkswaterstaat). Rijkswaterstaat works together with other water managers to clean roads, rivers, banks and beaches and to reduce the plastic soup in the oceans. “Because Catchy collects litter, it is prevented from flowing into the nature reserve and the North Sea where it breaks down into microplastics.”

The system is emptied monthly and is expected to collect about 200 kilograms of waste a month. This waste is sorted in Allseas’ laboratory and analysed for material type, size and weight. Hagelstein: “On that basis, we want to gain insight into the cause and extent of the litter problem in the Nieuwe Maas. We also make recommendations on how the collected litter can be processed sustainably and cost-effectively.”

Dutch Minister Cora Van Nieuwenhuizen (Infrastructure and Water Management) is following the pilot closely. “This is a good example of co-operation between the business community and the government to boost the development of important innovations. We want to get rid of the litter in our waters and this innovative approach with Catchy looks very promising. It’s also great that Catchy runs entirely on wind and tidal currents and therefore uses energy smartly.”


Article by Sabine Browne, Waterways Ireland