Princes Channel - Environmental Focus

With a view to improving safety, and with the objective of maintaining a more consistent depth profile in the southern approaches, the PLA have conducted studies in the Princes Channel, the busiest approach to the Thames.

A comprehensive Environmental Assessment (PDF – 1.7 Mb) of the likely effects of dredging works, including current, overflow and plume modelling (of the likely preferred dredging scenario), has shown that the sand removal will not significantly affect either the water flow at this location, or water quality. The environmental review has similarly concluded that there are no significant issues in respect of ecology, fisheries etc.

Click here for further Information on the archaeological aspects of the Princes Channel development. Information is also available on Wessex Archaeology's web pages (opens in a new browser window).

The PLA completed the first stage of the dredging of Princes Channel in 2006. Approximately 350,000m³ of sand was taken from the channel and used in a regeneration prject at Rochester Riverside. In line with Government regulations, and in accordance with the London Convention and OSPAR requirements, the use of the sand from the PLA's navigation channel removed the need for the use and depletion of more limited natural resources.

The dredged sand was delivered to the Rochester site by the dredging company Van OOrd and pumped from the dredger into a series of specially designed settling lagoons. This environmentally sustainable transport option resulted in a CO² emission saving of 13,888 tonnes over the course of the project (NISP 2006).

As part of this project PLA has characterised a sand recycling area in the diused North Edinburgh Channel in the outer Estuary. Some of the material from Princes Channel has also been placed at this site under a licence from the Department for Environment Food and Rural Affairs (Defra). For further information on the North Edinburgh Channel sand recycling area, see the PLA's Environmental Scoping Report (PDF 1.5 Mb)and Environmental Characterisation Report .

PLA's River Regime and Environment (RR&E) department has been monitoring the movement of the sand that has been placed at this site. The images below show some of the changes to the river bed over the placement period of several weeks. Areas coloured green show only small degrees of change, red areas have shallowed, and blue areas have become deeper when compared to the river bed before the placement.

Initial Survey Difference Model: one week into Sand Placement Phase

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Sand Placement Difference Plot: end of Dredging/Placement Phase

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RR&E will continue to monitor the movement of material away from the site with a view to confirming the long term use of the area for recycling sand.