Case Study – Thames Water – Sewer under rail scheme

Waterflow - liner installation 

John Sturrock 07973 254 298

Project: Sewer under rail

Customer: Thames Water

Sector: Utilities

Location: South East England


The challenge

Thames Water plc commissioned us to carry out pipe lining and other sewer rehabilitation work at more than 40 sites in just five months. All the sites were associated with railway lines, as they came under Thames Water’s Sewer Crossing Rail contract. Key challenges included:

  • Preparing teams and equipment to work during available track possession times (mostly at night) and with complex traffic management
  • Scheduling and co-ordination of work plans with both Thames Water and Network Rail colleagues
  • Working to tight deadlines
  • Devising innovative no-dig drainage rehabilitation solutions to overcome operational difficulties, like site access and confined space working.
Waterflow - liner installation John Sturrock 07973 254 298

Waterflow – liner installation
John Sturrock 07973 254 298

The solution

We assigned an experienced delivery manager to project manage the work. This ensured that there was continuity and excellent performance throughout the life of the programme.

We already had significant experience of working with Thames Water and Network Rail, which helped us co-ordinate the projects with key personnel at both organisations. Our teams are trained and qualified to work in main sewer environments, and on both Network Rail and London Underground networks.

A schedule of works was put together which best met the needs of both parties, in terms of priorities and minimising disruption of day-to-day operations. Risk assessments and method statements were devised for each project.

Each project was operationally assessed, in terms of the personnel and equipment needed, and the kind of rehabilitation solutions deployed. In a number of cases, we devised novel solutions to overcome specific technical challenges.

Services deployed included:

  • CCTV camera drainage surveys
  • Pipe jetting and desilting
  • Ultra violet cure in place pipe (CIPP) lining
  • Brickwork renewal
  • High pressure grout sealing.

The customer

Thames Water plc is the UK’s largest water and wastewater services provider. It maintains 67,000 miles of sewer, 2,530 pumping stations and 1.2 million manholes. Its 350 sewage works treat an average 4.4bn litres of wastewater a day.

Implementation – case study

Repair to live brick sewer

As an example of the challenges we faced, our team carried out a complex repair on the crown of a brick sewer. The sewer had to remain live while the repair was carried out because Thames Water had no way of diverting the flow.

Network Rail could not grant a track possession to facilitate the work. In addition, the signalling centre for the Anglian Rail route was directly above the sewer, restricting access.

To overcome these difficulties, chambers were opened up either side of the repair site, allowing wastewater to be over-pumped and taken away in tankers during the work. This gave our confined space team they time it needed to access the sewer.

Once the new brickwork was in place within the Victorian three-ring sewer, it was shored until it set. The team then high-pressure grout-sealed the brickwork to finish the job. Voids and redundant sump holes were also infilled.


  • During the programme we completed repair and rehabilitation projects at 42 sites
  • All work was completed within the five-month timeframe
  • The programme cost £800,000, which was £100,000 less than Thames Water budgeted for
  • All work was carried out without a reported health and safety incident.