London Tunnel Water Ring Main Design and Analysis of a Tunnel Ring Main and Pump Out Shafts

Study Scope

The London Water Ring Main is a major part of London’s water supply infrastructure. It consists of 80 km of 2.54 m (100″) underground concrete tunnel sections and is used to transfer potable water from various water treatment works into the Central London distribution zones. Hydraulic Analysis have been involved in the design and analysis of the ring main since its conception in the 1980’s and we still run the mathematical models of the ring main as it is planned to continually extend it through to 2025 as the infrastructure of London develops.

The ring main is well below the level of most water mains at a depth of between 10 to 60 m below ground level. It is connected to the water supply zones by some 20 shafts that extend from the ring main to ground level. The ring main serves as a partial alternative transfer system to existing trunk mains which are increasingly experiencing leaks and bursts due to their age. Thames Water operate some of the oldest pressure mains in the world (dating back to 1838). In addition to the model of the ring main, Hydraulic Analysis have calibrated models of all Central London distribution zones and we are regularly asked to review changes to zonal operation. This has included the specification and optimisation of numerous pressure control valves which have been installed in the past 10 years to reduce operating pressures and leakage rates in key areas of London. All of our London Water Pressure Zone models include the numerous pump out shafts from the the London Water Ring Main.

We are often used to investigate pipe failures in order to identify the cause of the failure and to determine if surge was a contributing factor. The findings (which can include site pressure and flowrate monitoring) are used to ensure further failures are prevented.

System Tunnel Ring Main
Location London
Scope Dynamic Design Study
Client Thames Water
Study Date 1986 – 2010
Length 80 km
Fluid Drinking Water
Capacity 1,300,000 m³/d