Maintenance dredging is carried out approximately every two months to ensure that Harwich Harbour’s deepwater channel remains at the charted depth. Each round of dredging involves removal of about 500,000 cubic metres of silt from the harbour.

The dredger generally has a full load after working for 30 minutes in the harbour. This material is then taken out to the licensed Inner Gabbard disposal site and released in 30 metres of water to disperse on the tide in what is known as a ‘dispersive site’.

The Authority also uses it’s own patented machine – Tiamat. The machine dilutes silt with seawater and disperses it eight metres above the bed of the harbour from where the material will move out of the harbour on the tide. The use of Tiamat is more natural, as the silt is allowed to move around the harbour, and reduces the CO2 footprint of the dredging operation because there is no requirement for trips to the disposal site.