November has seen Tideway take further significant steps on the construction of the £4.2 billion supersewer for London.

The secondary lining on the 7km western section of the tunnel has been completed, marking a significant milestone for the Tideway project.

Secondary lining is required to provide additional strength to the super sewer and to create a smooth surface over which flows will travel once the sewer is operational in 2025.

The primary lining is created by placing precast concrete segments into place to form a ‘ring’; the secondary lining is poured wet, in situ, around a huge machine called a ‘shutter’.

The secondary lining works in the western section started in March 2021 and have required more than 800 individual concrete pours to make the journey from Acton to Fulham in south-west London.

The concrete was batched on site at the Carnwath Road Riverside site in Fulham and delivered to the six shutters by concrete trains known as bullets to a pump located on a logistics crossing within the tunnel.

Around 48,000m3 of concrete was used to create the secondary lining in this section of tunnel.

The main drive of the 6.9m internal diameter, 7km tunnel was completed by tunnel boring machine in late 2020. The team are now preparing the site to undertake the secondary lining of the main shaft at Carnwath Road Riverside.

Connection tunnel linking 45-metre-deep shaft at Chelsea embankment now complete

A connection tunnel linking a 45-metre-deep shaft to the main super sewer has been completed at Tideway’s Chelsea Embankment site.

The 50-metre-long tunnel, under construction since May 2020, has seen the final construction operatives depart and the removal of lighting.

It connects to the shaft, excavated within a dry cofferdam on the foreshore, to the main Thames Tideway Tunnel beneath the Thames. The roof slab on top of the shaft has also been completed.  

Work at this site will intercept one of the most polluting Combined Sewer Overflows preventing sewage pollution in the River Thames.

Floodable terraces at Chelsea Embankment recently completed

New public spaces along the River Thames are becoming more visible with the completion of terracing at Tideway’s Chelsea Embankment site.

As secondary lining of the main super sewer beneath London progresses, work continues above ground at 24 constructions sites, including seven riverside locations where new public areas will be created.

At Chelsea, in front of the Royal Chelsea Hospital, the intertidal terraces are now complete and architectural brickwork is progressing as the team reinstates the north site across the road from the foreshore.

When construction of the Thames Tideway Tunnel is finished, three acres of new spaces will be created along the route of the river while parts of the sites at Chelsea and Victoria Embankments and at King Edward Memorial Park will be ‘floodable’ at high tides. The largest public realm will be located at Blackfriars Bridge.

At Chelsea Embankment, Tideway is working across two sites - north and south. The south site located on the foreshore lies within a cofferdam, a dry working area built out into the river. Here, a 45m-deep shaft links the site to the main super sewer below the River Thames via a connection tunnel. The roof slab at the top of the shaft has now been completed.

Across the road on the north site, a 23m-deep overflow weir chamber will receive sewage that overflows from the existing Low Level 1 sewer and direct it towards the main tunnel via a connection culvert. Work has now begun on reinstating this site including the footpath.

Super sewer ventilation columns installed along Victoria Embankment

Giant bronze ventilation columns have been installed for the first time on the central section of the super sewer project.

These huge, 5m-high columns at Victoria Embankment will serve as an exhaust system, removing air displaced by flows into London’s new super sewer. This air will be filtered through air treatment chambers.

Nineteen of these ventilation columns are required across the Tideway project to regulate the gases within the super sewer, with a number already in place.

And each column is inscribed with newly commissioned poetry celebrating the local area’s heritage, often with reference to London’s ‘lost rivers’.

The columns at Victoria Embankment will be complemented by the bronze-finish balustrade around the edge of the foreshore structure, which is partially completed.

Giant acoustic shed dismantled after five years housing Tideway's work on super sewer

Finally, one of the largest temporary structures on the super sewer project has now been dismantled at Tideway’s Kirtling Street site in Battersea.

The giant ‘acoustic shed’ housing Tideway's work on super sewer which was built to contain noise and dust to allow for 24-hour tunnelling has now been dismantled after five years.

It was erected in 2017 to cover the 30m-wide, 40m-deep shaft used to launch Tideway’s first two tunnel boring machines.

The shed was 21 metres high, with a footprint around half the size of St Paul’s Cathedral in the City of London.

Two cranes operated inside the structure around the clock while Tideway’s tunnelling work was underway.

The cranes completed more than 100,000 safe lifts during their five years of operation, lifting more than 56,000 tunnel segments 40 metres into the tunnel below.

The shed is now being repurposed at Laing O’Rourke’s Explore business at its Centre of Excellence for Modern Construction – Europe's largest and most advanced pre-assembly manufacturing facility.