In 2018, De Vlaamse Waterweg (the Flemish Waterways Authority) invited innovative tenders for a contract to develop and install plastic collectors for floating debris at 10 locations on various waterways around Flanders.
In 2019, De Vlaamse Waterweg picked DEME’s innovative design to be implemented near Temse Bridge on the river Scheldt. The special location with tidal conditions of up to 6 metres, alternating directions of flow and water debit rates of 2 metres/second on a busy shipping route, combined with the ingenious design, the fully autonomous operation of the plastic collector and a supplementary remote 3D Virtual Reality control are undoubtedly what clinched it for the contracting authority.
From the preliminary design phase, DEME included Bolina Booms’ tried and tested floating debris booms in its design. The 2 giant arms were intended to act as a funnel, directing the floating debris towards the plastic collector where it would be “trapped” in order to then be disposed of by way of a litter container and an autonomous vessel. Because of the extreme tidal conditions, Bolina D-500 pile drivers were put in place at the start of the booms, which are to accommodate the entire 6-metre difference in height 4 times a day. But near the pontoon too, i.e. the “plastic collector”, a special self-engineered “axehead” roll system was installed for the connection between Bolina’s floating debris booms and DEME’s debris collector. The new roll system is to enable free movement between the debris boom and the pontoon in case of heavy wave action and tidal conditions, without losing plastics or floating debris.
In the spring of 2020, the assembly of the 2 Bolina floating debris booms was prepared on the tow path. Both debris booms are made from a single full length section, without adapted or other couplings in order to maintain maximum tensile strength under these unusual conditions. The northern boom is 103 metres in length. In March, the southern boom – the longest Bolina floating debris boom ever to be built – was assembled into a single section that measures 175 metres in length.
Because of the Covid-19 restrictions however, the parties involved had to wait for July to come round before the entire system was actually able to be installed on the river Scheldt.
The plastic collector is operational 24/7 and is constantly monitored by cameras. In association with Antwerp University, Afdeling Bos en Natuur (the Flemish Woodland and Nature Division) and obviously De Vlaamse Waterweg, the floating litter collected is to be weighed and sorted for an entire year in order to get an idea of the kind of floating debris being removed. Is the litter man-made or natural? The investigation of the litter will also screen for factors such as quantities, particle size, time periods, impact on the fish population, etc.