Siltation is a continuous phenomenon that takes place in most of our ports and waterways. In order to guarantee the desirable water depths on a continuous basis it is necessary to carry out regular maintenance dredging. Especially for the smaller projects this means a heavy financial burden on the port management as dredging becomes generally spoken more efficient with increasing size of the port especially when using the more traditional dredging techniques.
rnrnWater Injection Dredging (WID) is a relatively new dredging technology developed by Eng. R.N. Van Weezenbeek some 25 years ago that can solve this problem in many cases. The technology has been further developed and is now available throughout the world.
rnrnWID is based on a concept that moves the sediment by using mainly natural forces present in the environment. This technique injects high quantities of water into the top layers of the underwater bottom in order to fluidise these layers and to create a density flow over the underwater bottom.
rnrnIn this way the sediments remain in the natural ecosystem and long lasting, cumbersome permit procedures can be avoided in some cases as the equilibrium of the ecosystem is far less disturbed because the sediment is just brought back to the ecosystems where they originates from.
rnrnHowever, because of the characteristics of this technique the range of projects in which WID can be used efficiently is significantly smaller compared to the traditional dredging techniques and control of the quantities of sediments that are moved during a WID operation is far less obvious. Therefore, a good knowledge of the WID technique and its constraints is a prerequisite to enable authorities to select the projects in which WID can be an added value or cost saving to them.
rnrnTo inform and support the world community in this decision PIANC decided to gather all available knowledge on this technique in a working Group report.
rnrnIn this report WID has been described and discussed in detail with emphasis on the following elements:rn
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- Theoretical considerations and physical principles of the new dredging technique
- Natural boundary conditions needed for an efficient use of WID
- List of typical applications for the WID technique
- List of available WID equipment throughout the world
- Environmental considerations to be taken into account when using WID
- Monitoring needs
- Typical contract conditions that can be used for WID projects
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Furthermore, a number of typical projects sheets have been added in the appendices of this report.rn
