King Edward Memorial Park CSO Diversion

Mariners are advised that on or around the 16th October 2024, and for a period of two months, the Tideway Tunnel Combined Sewer Outfall (CSO) at the King Edward Memorial Park site will be diverted to the river. 

During this period the CSO may discharge rain-water and untreated sewage into the river whenever there is, or has recently been, rain in the local catchment area. The discharge amount and velocity will vary, but during a storm this could be up to 6 knots, lessening the further from the outfall you are (example modelled flow velocities are included at the end of this Notice). Manoeuvrable motorised vessels travelling within the navigable channel will likely feel little effect. 

The approximate location of the CSO on the King Edward site is shown in red on the chartlet below. 

A set of warning lights will be mounted vertically in front of a black backboard on the cofferdam above the CSO. The lights will flash a yellow alternating 1 second pattern, visible day and night from 045° to 315° at a range of up to 200m, whenever the CSO is discharging or likely to discharge. Tideway advise the lights will activate approximately 8 minutes before any discharge will occur. 

CSO discharge alerts and warnings will be broadcast by London VTS on Ch 14. Additionally, the live status of each CSO (not including Putney) is available on the PLA website.

Routine VTS broadcasts will also include a warning if Tideway inform us there is a likelihood there will be a discharge within the next hour from the site. 

Human powered recreational craft, lower powered vessels and craft engaged in towing are advised to avoid the area over the slack water period (around two hours over low water and an hour over high water) if there has been heavy rain or 'if there is a Met Office weather warning for rain or storms in force for the London area. 

After this four-month period it is expected that the CSO will be fully connected to the main Tideway Tunnel which will reduce the number of these discharges directly into the river to approximately 3-4 a year. A new Notice will be issued at a later date to advise of permanent Tideway Tunnel operations. 

Further information on the characteristics of the CSO discharges, assessments of risk and potential impacts on mariners which were undertaken by Tideway’s designers are available on their website www.tideway.london/contact-us/document-library and follow the link to CSO DISCHARGES - RISK TO NAVIGATION. Mariners should consult these documents when passage planning.

(These links will take you to a third-party website which does not belong to the Port of London of Authority and may have different security, privacy and accessibility standards.) 

Example discharge plumes and velocities in m/sec for a 5 year return period discharge 

(1 m/sec = 1.94 knots)