Seen left, a Trailer Suction Hopper Dredger (TSHD), the most common tool for maintenance dredging, removing marine and alluvial deposits from a navigation channel. The dredged arisings are usually disposed of at sea, subject to the issue of appropriate consents and licences.

In environmentally sensitive areas the regulating authorities may require stringent monitoring to be observed during dredging operations.

The correct choice of plant for a particular project is important. Enclosed areas are difficult to access with a TSHD and alternative methods may be necessary.

On the right is a Backhoe dredger removing soft sediments from inside the dock at Workington in Cumbria. Dredged material is loaded onto barges for disposal at sea.

Backhoe dredgers are capable of removing material very precisely, are particularly good at cleaning the face of berth pockets and are insensitive to debris relative to suction types.

A plough, or bed-leveller, is an integral part of most modern day maintenance dredging spreads. With most methods of dredging, ridges or localised high spots will remain after bulk dredging. The plough is used to level these and move material into adjacent low spots.

The plough, seen left, is normally towed behind a tug, which often doubles as a survey vessel. Some TSHD’s have a large plough on their stern that can be used while dredging, but this is not common. Ploughs are also extensively used to move bed material from inaccessible areas to a location accessible by a TSHD.