About the dredging vesselsTrailer Suction Hopper Dredge Trailer Suction Hopper Dredges, such as the Queen of the Netherlands, will be used to carry out most of the dredging works in Port Phillip Bay. A trailing suction hopper dredge is one of the world’s most capable and technologically advanced dredging vessels. It meets all the requirements of latest best practice procedures and comprehensive safeguards, and an experienced, professional crew will help ensure operational safety during dredging. The vessel is designed for both shallow and deep water operations and the large hopper capacity, one of the largest in the world, gives significant economies of scale. It is highly manoeuvrable and with powerful pumps and advanced technology, dredging is fast and accurate, and the inclusion of an environmental “green valve” on these vessels substantially reduce turbidity associated with dredging. The valve is located in the overflow system and adjusted to reduce air being trapped in discharged water. This means sediment settles to the seabed quicker, reducing turbidity. The vessel will not operate in overflow mode when dredging contaminants. Backhoe Dredge A backhoe dredge is a hydraulic excavator equipped with a half-open bucket that is raised and lowered to the seabed to remove material. The dredge is placed on a pontoon with three legs (or spuds) that provide a stable platform during dredging. A backhoe dredge will be used in areas inaccessible to a TSHD, such as part of the Yarra River Channel. Grab Dredge A horizontal profiling grab dredge is fitted with a grab bucket, which can be fully closed to prevent dredge material escaping whilst moving through the water column. It is anticipated the grab dredge will be used to dredge berth pockets, inaccessible to a TSHD, which contain contaminated sediments. Support Equipment Other contingency equipment may be required to assist the dredging works and reduce potential impacts of the project. These include:
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