A barge mounted crane has moved into position in the Thames near Blackfriars Bridge. Manoeuvred into place by two boats, Shake Dog and Bull Dog, the crane’s arrival signals the beginning of one of the most audacious, and controversial, pieces of civil engineering in recent times.

The 15 mile Thames Tideway Tunnel has begun, updates Sir Joseph Bazalgette’s impressive sewage system and aims to do as he wished – to keep the river free of raw sewage.

Fittingly, the company taking the project forward derives its name from the Victorian visionary – Bazalgette Tunnel Ltd – and the mobile crane sits almost on top of one of his original intercept sewers. His remarkable work remains the backbone of London’s sewage system.

But not without cost. The price is £4.2billion – borne by Londoners with a surcharge rising to about £25 – but the toll will mostly be felt by the construction sites on public spaces dotted along the length of the route.

Groups such as Save Your Riverside, and Save King Edward Memorial Park sprang up when residents discovered they faced years of disruption. They formed protest groups, lobbied MPs, drew support from local celebrities (like Patrick Stewart) collected signatures and, in the case of Southwark Council, sought legal intervention over Chambers Wharf (which was thrown out because the papers arrived a day late).

They won some concessions but lost the argument.

Proposed tunnel route

Andy Mitchell, CEO at Tideway, the delivery organisation for the Thames Tideway Tunnel, said: “Our task over the next seven years is quite simply to make sure London has a sewerage system capable of meeting the capital’s modern-day needs.

“This is a once in a generation opportunity and we are determined to raise the bar in every way, not least the way we treat local communities most directly affected by construction works.”

Biggest infrastructure project

The Thames Tideway Tunnel is set to be the biggest infrastructure project ever undertaken by the UK water industry. The new sewage storage and transfer tunnel helps address sewage discharge levels to the tidal section of the River Thames.

The tunnel will intercept sewage from the 34 most polluting points along the river before transferring it to Beckton sewage treatment works in east London via the Lee Tunnel, which has already been constructed to take wastewater away from the river.

The sewer tunnel follows the river from west London to Limehouse, where it then continues north-east to Abbey Mills Pumping Station near Stratford. Tunnelling will be launched east and west from the Kirtling Street shaft in Battersea, from where it will have to negotiate a spaghetti dish of underground tunnels servicing the capital.

Environment Secretary Elizabeth Truss said: “The Thames Tideway Tunnel will be a fantastic example of world leading British engineering at its best. It will also boost economic growth across the capital, generate more than 9,000 jobs and bring huge benefits to the natural environment by protecting the Thames from sewage.”