The firms provide engineering consultancy services on Severn Trent’s strategic water grid, with the Elan Valley Aqueduct being a key project.
The Elan Valley Aqueduct is 117km long and runs from the Elan Valley Reservoirs all the way up to Birmingham.
Ken Ford, Atkins’ project delivery manager and programme manager for the project, said: “The Elan Valley Aqueduct, which is the main scheme that my team has been looking after over the last couple of years, supplies raw water from the Elan Valley reservoir complex in Wales by gravity all the way into a treatment works in Birmingham and we’ve been helping Severn Trent to ensure that it is in good condition.”
The Birmingham Cooperation built the aqueduct between 1893 and 1904, as the supply of clean water to the city was short and there were major epidemics of water-borne diseases, including typhoid, cholera and diarrhoea.
Now, in operation for over 100 years, the aqueduct, which helps to ensure a water supply to SevernTrent customers, is starting to show signs of ageing.
“It’s high quality raw water and at the moment it’s almost a single point source for Birmingham, so if it fails it would cause a lot of disruption,” said Ford.
There are four construction schemes, worth about £75M, underway at the moment as part of the 10-year Engineering Consultancy Framework that Atkins and Arup, as well as other contractors have with Severn Trent. The conduit replacement scheme includes the replacement of a section of the aqueduct that is at the end of its life.
Ford said: “The key challenge with the aqueduct is that it is a single source of supply and you can’t simply turn the supply off and build a new one. Consequently, our teams developed options where we can maintain the existing flow and construct the new bypass section and then connect it through short time windows. The contractor, BNM Alliance, has just finished tunnelling the first scheme at Bleddfa.”
There are also two other tunnel bypass schemes, one at Nantmel and the other at Knighton, and a control system scheme to manage spills in the event of a blockage.
The team is also looking at ways of increasing the current supply of water (320M litres a day): “The Elan valley aqueduct is a good source at the moment. We are, however, looking at opportunities to increase that significantly capacity. If we can increase the capacity of the aqueduct it will ensure a reliable water supply for many years to come”.
The construction schemes are expected to be complete in 2020.
* Data provided by Timetric's Construction Intelligence Center.
Bringing the assets to the 22nd century
Severn Trent has the ambition of bringing its assets to the 22nd century with the use of technologies and digital approaches.
“We are starting to use more digital surveying techniques. Severn Trent currently only has the ability to close and drain [the aqueduct] for around four days a year so it can be inspected.
“When we get these window of opportunities we use a range of digital techniques to collect data, including laser scan surveys, 360 degree cameras, and GoPro cameras.This enables the team to start building virtual pictures of the conduit to improve the speed and accuracy of our work. We are starting to talk about it as a virtual site visit.”
Ford added: “We have also undertaken aerial flyover surveys. The high-resolution aerial photographs and stereoscopic images that were taken can be converted into 3D maps. This provides a whole virtual picture of the aqueduct underground and the route it takes above ground.”