About the scheme
Construction of a new 6.5km pipeline began in summer 2019 and was completed in spring 2023. It has connected Bristol’s existing trunk sewer in Lawrence Weston to the Frome Valley relief sewer near Cribbs Causeway and directs waste more efficiently around North Bristol to our water recycling centre in Avonmouth.
The majority of the sewer has been constructed by tunnelling underground using a tunnel boring machine, reducing the need to dig trenches. We have even tunnelled underneath the M5 motorway and Network Rail’s Henbury Loop freight railway.
The North Bristol relief sewer forms an essential part of our long-term sewerage strategy for the next 100 years.
Watch the video below to see how the tunnel was built using a tunnel boring machine and click the drop-down options to find out relevant information for each area of North Bristol where activity took place.
Construction of a temporary site compound and tunnel entrance in the hillside below Oasis Academy Bank Leaze began in August 2019. The tunnel boring machine (TBM) was scheduled to launch from this site in March 2020. However, the launch was postponed due to the Covid-19 pandemic. The TBM was eventually launched in June 2020 and was removed from the ground in February 2022 at The Bristol Golf Club in Almondsbury after completing its 5.5km journey.
A smaller section of sewer (approximately 1km) to connect the main tunnel with the existing Bristol network was also constructed behind Saltmarsh Drive, through the playing fields of St Bede’s Catholic College and behind Attwood Drive. Construction of this section and reinstatement of the area was completed in autumn 2020.
The site compound was removed at the end of 2022, which included Oasis Academy Bank Leaze’s grounds being reprofiled to form a new flat playing area above the flood plain. This was created at the request of the school.
Over the summer of 2023 year we been completing reinstatement of the Lawrence Weston Moor with seed harvested from neighbouring fields. This ensures the return of the original plant species
Similar to Henbury, a 30-metre-deep shaft and connecting sewer pipe was constructed in the former Filton Airfield – this was finished in November 2020, ready to receive the tunnel boring machine (TBM) by August 2021.
Once the TBM had finished the final leg of its journey, the two shafts at Henbury and Catbrain were fitted with mechanical and electrical equipment. Reinstatement of the airfield, Catbrain Hill and Medlar Close is now complete.
Our tunnel boring machine successfully completed its journey and arrived at The Bristol Golf Club on 28 January 2022, where it was taken out of the ground inside a site compound that we had built on the 15th fairway of the golf course.
The compound included a connection chamber to make the final link between the existing sewerage network and the end of the new tunnel.
Reinstatement of the golf course was completed in 2022, but throughout all of our work there, members were still able to play the full course safely. A new power supply to our kiosk will be installed by National Grid in early 2024 which will enable the removal of the temporary generator from the side of the course.
With the help of our very own trained sniffer dog Freya, prior to arriving on-site we detected 32 great crested newts, nine slow worms, three smooth newts, 11 toads and one frog, which we were able to relocate to a safer habitat before work began.
