Maintenance Dredging in the Port of London

What is maintenance dredging?
The periodic removal of shoals or sediments from existing navigational channels, berths, swinging moorings etc in order to maintain an appropriate safe depth of water for navigation, construction or operational purposes.

The Port of London

The PLA is responsible for maintaining navigable depths in the main channels of the tidal Thames.  In practise, the PLA prefers to move channels as a solution rather than undertake frequent large scale dredging campaigns.  However, there are a number of areas where sand waves and shoals form and it is not possible to move the channel, therefore, maintenance dredging must be carried out.  Table 1 sets out the PLA’s present maintenance dredging areas, methodologies, and frequency. 

In common with other harbours with a significant degree of commercial or recreational use, the general duties and functions of the PLA are managed under statutory powers – in this case the Port of London Act 1968 (as amended). 

Dredging falls under the conservancy function and, as with other harbour authorities for major harbours, the special legislation authorises the authority to deepen, dredge, scour and improve the bed and foreshore of the harbour etc.  Clearly this is within the context of maintaining navigational channels and removal of wrecks and other obstructions to navigation.  Hence this aspect of the conservancy function relates to securing safe and convenient navigation in the harbour.

Since the PLA’s powers are included in an Act of Parliament, the need to obtain consent for navigational dredging under Section 34 of the Coast Protection Act 1949 is removed.

As with nearly all important commercial harbours, the PLA’s special legislation prohibits persons other than the harbour authority from constructing works below mean high water or dredging without first obtaining a licence from the harbour authority.

Further information on dredging can be found at the website for the Central Dredging Association (CEDA).

Table 1 - Current PLA Maintenance Dredging Areas