Southern Water lays 1km pipe out into the sea off the Kent coast in latest phase of major construction project

Southern Water has completed the controlled sinking of a new outfall pipe nearly 1km long at Swalecliffe.

The engineering feat followed work by a specialist dredger, called the ‘Razende Bol’ and excavators working on the beach. The work has involved digging a trench that runs from Swalecliffe Wastewater Treatment Works out into the North Sea. 

The new pipe was manufactured in Norway in two parts, each approximately 500m in length. The pipes have been towed across the North Sea, to a port in the Medway and was harboured there until the trench was ready.

The new pipe arrived from the Medway port, was guided into position above the trench and valves were utilised to ‘sink’ the pipe into place. The trench will now be backfilled, to cover it up. 

The new pipe is made of High-Density Polyethylene, has an internal diameter of 1107.6mm. The new pipe will be 959m from the sea wall to the end of pipe, approximately 410m longer than the existing sea outfall pipe.  

John Penicud, Director of Wastewater Operations at Southern Water said: “The Swalecliffe engineering project will replace a sea damaged outfall pipe, as part of a major upgrade of its wastewater treatment works and a regulatory requirement, it will allow teams to install a much longer pipe in its place.”

Outfall pipes stop homes and businesses from being flooded. They are used as a last resort during and after heavy rainfall when storm tanks are full. This means any releases of stormwater from this outfall happen rarely. The new outfall pipe is further out to sea and further from local beaches and bathing waters.  

Crucially, this urgent work will take place alongside ongoing efforts by our Clean Rivers and Seas Task Force to drastically reduce our use of storm overflows like this one.  

These efforts, rolling out innovative nature-based and engineering solutions to this historic network of pressure release valves, are happening in the Swalecliffe area and throughout our region with a range of partners.  

We will continue to work with our partners to reduce the need to use the new outfall at all, by ensuring more rainwater stays in the environment and doesn’t enter the sewer network. 

Technical facts 

·       The new sea outfall pipe will have an internal diameter of 1107.6mm. 

·       The new pipe will be made of High-Density Polyethylene.  

·       It will be 959m from the sea wall to the end of pipe.  

·       This is approximately 410m longer than the existing sea outfall pipe.  

·       The new pipe has been manufactured in Norway in two lengths, each approximately 500m in length. The pipes will be towed across the North Sea, prepared and then sunk into position.