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WID vessel Jetsed works mainly in the United Kingdom and the Netherlands. The longest running WID contract is the 19-year maintenance dredging contract in São Luis, Brazil. On the other side of the globe, WID vessel Sagar Manthan is deployed in Indonesia.
In 2013, PIANC, the World Association for Waterborne Transport Infrastructure, issued the Guidelines for Water Injection Dredging, which contain information on all aspects of WID, including advice for monitoring campaigns, environmental impacts and contract forms. The guidelines represent an opportunity for every port authority that faces regular maintenance dredging. ‘WID is an alternative to traditional dredging with a trailing suction hopper dredger. The technology is proven, and while the environmental impact of this technique may be different, it is no more significant than traditional dredging methods.’
Van Oord’s water injection dredgers – eleven in all – are deployed world-wide. Water injection dredging has
been used widely in India, Brazil and northwest
Europe for many years.
WID vessel Sagar Manthan arrived in Indonesia in mid-2012. It has been deployed on several Indonesian projects, such as the construction of the access channel in Kapuk Naga Indah and the development of the port of Tanjung Priok. The Surabaya West Access Channel is its current project. The Sagar Manthan is so busy because of its abilities to dredge in shallow water and close to quays. In this way it perfectly and economically complements the work of the large trailing suctions hopper dredgers.
An aluminium plant with a port and approach channel were built near the city of São Luis in Brazil in 1983. Regular maintenance of the channel and the harbour basin became necessary as a result of unexpected sedimentation. The São Luis contract was signed in 1995, which makes it the longest-running WID project. Currently, the Draga Rio Madeira, sister-vessel to the Draga Tocantins, is operating in São Luis. Both dismountable vessels were built in Itaguaí, Brazil. Van Oord also carried out maintenance work in Itaguaí with Iguazú (11 years) and Camorim (1 year).
‘The innovative characteristics of WID are often not covered by local legislation governing dredging permits. We consider all concerns that our clients and stakeholders may have. A test period combined with a monitoring program is the best way to make our clients, consultants, stakeholders and legislatures confident in the WID method we use.’
Someone who knows everything about WID is Van Oord Engineering Geologist Marcel van den Heuvel. ‘Each and every one of our clients has different requirements, needs and opinions, and we tailor our approach to the area we work in. WID is an efficient way of maintaining the depth of a port or river. When the boundary conditions are in place, WID is the most technically, environmentally and economically effective dredging method. Injecting water under low pressure into the seabed brings the sediment into motion.
Natural processes, such as bathymetric changes and river and tidal currents control the direction of the horizontal transport of the sediment until it has been brought back into its natural system. This makes it important to understand the hydrodynamic conditions in both the dredge area and its surroundings, including understanding natural phenomena such as the origin of the sediment and the transport, erosion and deposit of the sediments.’
The natural way
Water injection dredging (WID) is a relatively new hydrodynamic dredging technique developed a little more than 25 years ago. It is a cost-effective, environmentally sound solution to some specific dredging problems. Van Oord is the market leader in this relatively small but growing segment of the dredging industry. It is a clear example of Marine ingenuity.
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Water injection dredging