Posted on November 12, 2020
The Port of Rotterdam Authority has been carrying out trials with water injection dredging at a site in the extensive port with a view to reducing both costs and environmental impacts.
The technique involves injecting water into the sea bed of the project site so that this creates a mixture of water and sediment. This mixture can then be persuaded to flow in a specific direction under the influence of both gravity and currents to help maintain the channel depth at its prescribed level.
Over the past two years, the Port Authority has been conducting trials with water injection dredging in the Caland Kanaal which is one of the main shipping channels near the entrance to the port and they set up a sludge repository in the waterway for this purpose. Injecting the sediment with water once every 6 to 8 weeks rather than removing it with a trailing suction hopper dredger has cut dredging costs at the site and now the Authority is examining whether it would be realistic to expand its new dredging program in Rotterdam with water injection dredging.
The current study is part of the Port Authority’s PRISMA research program, which looks into new dredging methods and how sediment reacts to these techniques. PRISMA stands for PRogramma Innovatie Sediment MAnagement. and the programme was set up by the Port of Rotterdam Authority to explore new and innovative methods and opportunities within its dredging program and increase the insight into the sediment’s specific characteristics. These PRISMA studies are being performed in partnership with various research institutes, including Delft University of Technology, Deltares and MARIN.
The Port Authority is responsible for keeping Rotterdam’s harbour basins and waterways at the specified depths and this involves dredging around 5 million cubic meters of dredged material every year mainly using established dredging techniques which can obstruct the movement of shipping. Water injection dredging is seen as the most promising means by which to remove clean sediment from both berths and waterways for maintenance purposes and it can also be used in areas that can be difficult to access as well as in berths that are in regular use.
By Dag Pike