North Bristol Relief Sewer

Name: North Bristol Relief Sewer (NBRS)

Client: Wessex Water

Approximate Cost: £55 million


The North Bristol Relief Sewer (NBRS) forms an essential part of the long-term sewerage strategy for the next 100 years. Construction of the new 6.5km pipeline began in summer 2019 and is planned to finish by spring 2022. It will connect Bristol’s existing trunk sewer in Lawrence Weston to the Frome Valley relief sewer near Cribbs Causeway and will provide direct transportation to the sewer treatment works at Avonmouth.

The route crosses several key transport assets and includes tunnelling under the M5 motorway and Network Rail’s Henbury Loop. The majority of the sewer will be constructed by tunnelling underground using a large tunnel boring machine, linking together a series of manholes up to 30 metres below ground.

The project will create an increase in storage capacity ahead of future North Bristol and South Gloucestershire developments as well as reduce the flooding risk within the existing network. The new sewer system provides approximately 8000m³ of storage during high flow events. The storage volume will be mobilised through the use of large automatic level controlled penstocks located in five chambers interspersed at strategic points along the NBRS tunnel.

Our Role:

LJR Engineering Ltd has an established history of delivering high quality services of this nature for other clients and this was a fantastic project to develop a new relationship with Wessex Water. LJR has been employed to steer the MEICA element of the project, providing expert consultation and support to the contractors throughout the design, development and installation process, ensuring the new systems have been designed and engineered to the correct industry standards. LJR has been involved from the early stages of the project and played a key role in the installation, commissioning and final signoff stages of the project. We have driven the MEICA design reviews, providing critical assessment against the operational requirements and industrial standards, to ensure each system is engineered to achieve safe accessible maintenance and effective operation.

Throughout the project LJR will work closely with the contractors to ensure all civil, mechanical and electrical works have been delivered and installed in the correct sequence, ensuring risk assessments and method statements are correctly practiced throughout the installation and commissioning activities. LJR will provide expert guidance and commissioning support whilst developing detailed commissioning procedures and method statements, before providing the principle contractor with a detailed commissioning manual including operational instructions, certification and operator training, preceding the handover to the client upon successful completion of the project.