Sprowston Blue Boar Lane Rising Main (2025)

Rehabilitation project addresses critical operational challenges while minimising environmental and community impacts

By: Anglian Water’s @one Alliance

Published: January 22, 2025

Vanderkamp UK’s overpumping pipework - Courtesy of Anglian Water’s @one Alliance

Sprowston Blue Boar Lane Rising Main in Norwich plays a crucial function in management of wastewater for the local community. The rising main connects the Sprowston Blue Boar Lane Pumping Station to the sewer network; facilitating efficient wastewater transport. The pipeline’s strategic location near housing developments, a roundabout, and a Tesco supermarket and fuel station underscores its importance to public health and safety. The region’s growth and the rising main’s proximity to high-traffic zones emphasise the need for a reliable and resilient infrastructure.

The issue

As assets age, they start to work less efficiently than they did at their installation. Anglian Water Service had recently noticed this within the Sprowston Blue Boar Lane Rising Main, as it had experienced multiple bursts in recent years, including incidents on November 18, 2020 and August 20, 2021. These failures occurred near critical infrastructure, including residential areas and a busy roundabout adjacent to a Tesco supermarket and delivery bay.

The existing 450mm glass reinforced plastic rising main’s deteriorated condition necessitated immediate action. Additionally, the aging infrastructure had a rough internal surface, contributing to inefficiencies in flow and elevated operational risks. The bursts posed significant risks, including potential pollution events through contamination, which is a risk to the public health of the surrounding area.

Design considerations

Anglian Water’s @one Alliance sewer rehabilitation team acted quickly to come up with a solution for this issue; realising that a comprehensive rehabilitation plan was required to address the identified issues to ensure long-term reliability and compliance with performance standards. To complete this, the project’s execution followed a systematic approach to minimise disruptions and maintain service continuity.

omplex overpumping arrangement – Courtesy of Anglian Water’s @one Alliance

Thorough assessments were undertaken to ensure the most effective and future-proofed solution was selected, so during the design phase, the Anglian Water @one Alliance team carefully explored multiple options to determine the best approach for this project. Replacing the existing GRP pipe with a brand-new PE pipe along Blue Boar Lane was initially considered, however, trial hole investigations quickly revealed the area’s significant congestion of utilities, including gas mains and electric cables, which posed substantial risks to the project.

Further construction techniques were evaluated, but ultimately the installation of a 9mm thick, water-cured liner within the existing pipe was determined to be the optimal solution, offering a practical and efficient way to navigate the complexities of the site.

The solution required maintaining a flow rate of 142 l/s and thanks to the smoother surface of the new liner, hydraulic modelling confirmed that there was no adverse effect from the reduced bore resulting from the relining process.

Hydraulic modelling also accounted for maximum and minimum pressure conditions, including surge pressures during operation and pump trips, and it was determined that the liner needed to withstand pressures of up to 5.15 bar and negative pressures down to -0.5 bar.

The final design not only met hydraulic modelling criteria but also ensured sufficient pressure handling, making it robust and efficient under operational conditions.

Blue Boar Lane Rising Main: Supply chain – key participants

Client: Anglian Water
Project delivery: @one Alliance
Bypass pipework: Vanderkamp UK
Cured in place relining: OnSite Central Ltd
Crane hire: Crowland Cranes

Temporary works

The initial challenge the team faced was the need for the sewer to be empty while the relining rehabilitation works took place. To resolve this challenge and ensure uninterrupted service to customers during construction, a temporary 450mm diameter, above-ground pipe needed to be installed to divert sewage flows, complete with pipe bridges at road crossings and entrance points. The temporary pipeline allowed the existing GRP pipe to be isolated and the rehabilitation could commence.

Complex overpumping arrangement – Courtesy of Anglian Water’s @one Alliance

The installation of the temporary pipework was a significant undertaking, and one that required close collaboration with Vanderkamp UK. Working together, the @one Alliance/Vanderkamp UK team considered sustainable solutions to mitigate flows and ensure the continued integrity of Anglian Water’s infrastructure.

Liner installation

With the overland pipework in place, the team drained the existing GRP rising main and undertook CCTV surveys to assess its condition.

The works required the installation of a 9mm thick, water-cured liner within the existing pipe, which would create a smooth and durable interior surface with improved hydraulic performance. Alongside the installation of the new liner, a new air valve at the high point near the Tesco loading bay was installed to optimise the pressure going into the pipe.

Once the work was complete, the relined pipe was reconnected to the network and tested and commissioned for performance before being handed back to Anglian Water. The site team then decommissioned the overland pipework and restored the area back to its original condition.

The team relined 680m of the existing 450mm GRP rising main, providing a robust solution which will last for many years to come.

Benefits of the solution

The rehabilitation of the Sprowston Blue Boar Lane Rising Main delivered numerous operational, environmental, and community benefits.

The installation of the 9mm thick pressure liner significantly improved the rising main’s durability and hydraulic performance for many years to come. The smoother interior surface reduced the resistance, enhanced the flow efficiency and minimised the energy consumption. By installing the new air valve, optimal pressure was maintained which reduced the risk of future bursts.
The solution also mitigates the risk of environmental contamination from wastewater spills and supports environmental compliance with regulatory standards.
The temporary overland pipework ensured uninterrupted service to our local community and the water-cured relining method was a cost-effective solution compared to complete replacement; minimising excavation and associated costs.
Thes solution provides longevity and resilience by providing over 50+ year’s lifespan of the pressure liner, which in turn reduces the need for frequent maintenance & also lowers the lifecycle costs.

Conclusion

By implementing innovative technologies and meticulous planning, the £1.5m project addressed critical operational challenges while minimising environmental and community impacts. The success of this infrastructure improvement project ensured continuity of service and long-term reliability, safeguarding the region’s wastewater infrastructure for decades to come.

The editor and publishers would like to thank Anglian Water’s @one Alliance for providing the above article for publication. The @one Alliance is a collaboration of eight partner companies that each provide specialist knowledge allowing the Alliance to deliver complex delivery projects in the most efficient way, reducing the cost to Anglian Water’s customers. The partners are Anglian Water Asset Delivery, Balfour Beatty, Barhale, Binnies, Mott MacDonald Bentley, Sweco, Skanska, and MWH Treatment.

(left) Temporary pipebridge installation at a road crossing and (right) the overpumping pipework - Courtesy of Anglian Water’s @one Alliance