Delta does it for Thames Tideway tunnel

As millions of tonnes of raw sewage spills into the River Thames each year, the Thames Tideway Tunnel project is working to build a new ‘super sewer’ to bolster London’s 150-year-old sewer system. With the success of the project paramount for the future of the river’s ecology as well as for the enjoyment of the city’s residents and visitors, the delivery team working on the West section of the multi-billion-pound sewage solution have turned to digital innovations to ensure accurate and efficient completion.

For a 7km-long section of the new tunnel to the West area of the project, which will act as a temporary storage for the combined foul and rainwater that overwhelms the city’s sewage treatment centre, the BAM Nuttall, Morgan Sindall, Balfour Beatty joint venture team wanted to ensure the integrity of the river walls and surrounding structures. Alastair Cruickshank, engineering survey manager for the joint venture, opted to bring in high-accuracy monitoring tools to closely watch any deformation of these aspects around the site, and also to assist in efficient delivery of the tunnel.

He said: “It’s critical that none of the works impact the surrounding structures that protect the city and provide homes to residents. We needed a system that would provide intricate detail on any movement and would give us that information as frequently as required and wouldn’t take up too much time, money or resource. Working with Topcon Positioning we found a solution that enabled all of these things with Delta.”

The team is using 10 of Topcon’s Delta monitoring systems both along the river walls and in the basement carpark space of a nearby exclusive apartment complex.

Alastair said: “The system gives me complete control from my desk and can automatically send alerts for any significant movement for us to keep a close eye on the area. All of the Delta systems are connected with Delta Link, enabling us to properly allocate resource as there’s no need for the team to be manually checking each of the instruments.”

Simon Crowhen, business development manager for geomatics at Topcon Positioning GB, said: “The Delta systems can operate for several years without the need for servicing depending on usage, so they’re a very reliable piece of kit for long projects such as this.”

Sir Joseph Bazalgette cleverly designed the current system to service a population twice its size at the time. Now, the population has exceeded four times the size of that day, nearing nine million. The system flooded into the Thames only twice a year in those days, but now, because of climate change the system floods every week on average. With this in mind, it’s critical that the project is delivered quickly and accurately, and so the project team are employing a number of technologies to assist.

A range of other Topcon technologies are being used on the project, such as Topcon’s GT505 robotic total station coupled with the FC-5000 field controller and MAGNET Field software, which are simplifying everyday survey tasks. Topcon’s GLS 2000 scanner is also being used on the project, increasing team knowledge in monitoring at long range the river foreshore and walls for scour. It is also used daily at short range to detect millimetre movement in buildings and bridges. In addition, the Tunnel Boring Machine (TBM) is being guided by Topcon robotic instruments to ensure the connection tunnel is positioned correctly, enabling it to fit the 1km tunnel precisely to the tight design alignment under the streets of London.

This section of the Tideway Tunnel project is expected to be complete by 2024 to ease pressures on the city’s sewage system for centuries to come.

For more information about Topcon’s monitoring solutions, click here.