Severn Trent project to reduce sewer flooding and improve river health in Stroud one step closer towards completion. 

Monday 18th September 2023

Severn Trent’s £25 million project to reduce sewer flooding in Stroud is moving closer to completion after its tunnel boring machines have finished laying 1.7 km of brand-new sewer pipes.

The water and waste company is transforming the network in the town to provide those living in Stroud with a reliable sewer network, as it will create more storage to protect homes and businesses from blockages and flooding, and also improve river health.

Four tunnel boring machines have been used to tunnel underground to lay the new pipes in order to minimise disruption above ground for residents. All four machines were named by the local community, or by those working on the project:


·         TBM Molly – named by Bisley Blue Coat School year six pupil Molly Forsyth who won a Severn Trent competition to name the machine.

·         TBM Suzanne – named in honour of the late mother of Will Hooper, then design team lead at Severn Trent’s contractual partners Galliford Try. 

·         TBM Lillian – named in honour of Lilian Faithfull CBE, a former principal of Cheltenham Ladies’ College who dedicated her life to advocate for women’s rights.

·         TBM Florence - named after the baby girl of Severn Trent community communications officer Shannon Currall, who has worked closely on the project.

And now Chloe Dobbs, project manager, has given the latest update ahead of it’s planned completion of Autumn 2024. She said: “It’s been great to be involved in a project such as this and it’s great to see how well it’s coming along. We’re making good progress – we’ve completed the laying of the trunk sewer with all of the tunnel boring machines which has been a big piece of work and we’ve finished laying the rings of the new CSO storm tank shaft which is 26m in depth.

“Using the tunnel boring machines has been so beneficial – they have been cutting through the earth, laying new pipes in their path without residents being aware of the amazing work going on beneath their feet.

“We’ve worked closely with businesses to mitigate any disruption and we’ve held customer drop-in sessions where it’s been great to meet customers with a keen interest in the project.”

The new CSO site, just off the Ebley Bypass, houses a storm tank, which will increase the capacity of the local network considerably. 

It will have smart controls that can hold water back during severe weather events, before returning it back to Severn Trent’s treatment works when rainfall has subsided and capacity to treat it is available. 

The capacity of the new storm tank will be 7,400m3 – nearly the equivalent of three Olympic sized swimming pools and over 24,500 bathtubs of water. 

Chloe said: “The new CSO site and extra capacity doesn’t only tackle the issue of sewer flooding, it will mean that there will be fewer spills into watercourses, such as the River Frome. Once finished, it will have a massive impact on the local area and will play a huge role in our Get River Positive commitment that by 2030 our operations will cause no harm to rivers.

Reflecting on what it has been like to manage a project of this size, Chloe, who started working as an apprentice for Severn Trent, described it as a ‘massive learning opportunity’. 

She said: “I moved into Severn Trent’s major projects team in March 2022 and Stroud was the first project I took on as project manager. It covers everything you would expect to see on a big project such as keeping all stakeholders informed and handling any questions they have, handling planning permission, highways agreements, and our involvement with the Environment Agency. 

“I really want to do all I can to deliver a successful project for our customers in Stroud, and I’ve loved meeting our customers across the town.

“Previously it would have been unusual for a female to be a project manager for projects on this scale, but Severn Trent as a company have been great in encouraging women into this space - everyone is treated equally, and I don’t feel as if I’ve ever been at a disadvantage. I hope it shows that you can go for it if you’re passionate enough and really want to make a career in this field.”