Improve waste and water supply for the future of a town
Severn Trent Water has invested £60M to upgrade the sewers and water supply network throughout Newark-on-Trent. The project (delivered in three phases by BNM Alliance) aimed to relieve 400 homes and business from sewer flooding and provide a robust water supply system which will serve the town for many years to come.
The project includes a 2.8km segmental tunnel passing beneath the town (including East Coast Mainline), 2km of pipe-jack tunnels, 2.55km of water mains renewal, 6 km of open-cut sewers, and more than 10km of new water mains mainly constructed in the town’s streets.
By the end of 2018, phases 1 and 2 (92.2% of the project) were completed including all tunnelling and wastewater shafts.
The terminal pumping station was operational, water mains renewal completed, all major town centre works finished, and 80% of the open cut sewers / new water mains were in place.
It was clear that the project would have a significant impact on Newark so the Newark Customers and Communities First Initiative was created with the focus to continually improve project delivery through engagement, understanding stakeholder needs and building these in throughout the project lifecycle.
The project was delivered in a way that not only minimised stakeholder impacts but brought stakeholders along on the journey.
Did you know …
25km of pipework was installed in one town to improve both foul and clean water networks, enough to stretch from Newark to Lincoln.
3km of the tunnel dug beneath Newark’s busy and historic streets, is large enough to drive a transit van under the town.
400 property owners no longer have to worry about regular sewer flooding, protected by a state-of-the-art pump station that could empty 65 baths every second that it operates.
Project achievements and benefits
The project alleviates flood risk to 400 properties across Newark. As part of the project, Severn Trent worked in partnership with Nottinghamshire County Council to deliver a 1:75 year level of surface water flood protection to 44 additional properties.
Newark is a rapidly growing town, with a 25% expansion of the town written into the local authority’s masterplan. This project provides new water mains to serve up to 750 properties. It also forms the initial infrastructure required and links with a wider strategy to provide for up to 16,000 new properties.
The existing waste and water networks are also being renewed as part of the project, helping to reduce leakage, water quality issues, the risk of supply interruptions for customers, and the risk of blockages within the sewers.
The project provided a fantastic opportunity for educational outreach with the local community. Several tunnel boring machine naming competitions with local schools were launched, presentations about the works in assemblies and lessons were carried out, and children were invited to the site to see the machines lowered into the ground and get up and close with the construction work.
How the work was done
Community engagement on the Newark project was the driving force behind project solution development ensuring that delivery focused on community interest and that the community had a stake in the project.
Key stakeholders were invited to form a collaborative team, including local councils, government agencies, customers and business groups. The team established constraints and stakeholder needs, incorporating these as strategic drivers in the development and delivery of the project.
This team ensured the most sustainable solution for Newark was implemented, engaging with the wider community to limit the impact of construction, leaving a legacy of understanding of the engineering challenges managed by the project team.
Involving the community in key project decisions ensured that the positive and negative aspects of different solutions could be truly understood. Detailed explanations of engineering principles, shared benefits and concerns about options, members going back to the wider community for buy-in and feedback all led to a level of emotional investment in the project. This was everyone’s project for the benefit of the town and a legacy of understanding is being left.
A key decision influenced ,by the forum was the construction of a recently completed 3km-long, 2.8m-diameter segmental tunnel rather than a 1.8m diameter pipejacked tunnel along the town’s busiest road through the town centre.
This larger tunnel wasn’t needed hydraulically, but allowed segmental tunnelling to be used and the construction of smaller ‘drop shafts’ in the town centre.
A 17-week, one-way system was implemented rather than 18-months of road closures and traffic control that would have been required to accommodate pipejacking.
Engaging with the stakeholders helped improve their understanding of the engineering principles and they could, in turn, explain these to the wider community and assist the project team in delivering a wider engagement plan.
This resulted in almost 20 public exhibitions, nearly 50 presentations to schools, engineering groups, business groups and 20 site tours for graduate engineers, ICE members, local interest groups and customers.
The local community’s knowledge was used to learn about things such as the significant archaeological potential, enabling the solution to be focused on minimising impacts.
For example, an archaeological strategy was prepared in partnership between Nottinghamshire County Council, Historic England, BNM, Severn Trent Water and local archaeologists.
The strategy ensured the scheme was designed to reduce impact, that any required archaeological works were programmed in line with construction, and importantly that any learning was shared with the community.
In order to achieve minimal disruption in the town, many engineering solutions were employed, including:
- A variety of shaft construction methods (secant pile, segmental caisson, sheet pile cofferdam, vertical drop shafts) with shafts up to 15m diameter and 22m deep
- Six different tunnelling machines were used, on tunnels between 600mm and 2.8m diameter
- Where possible, surface water has been removed from the system, which reduced short-term impacts and long-term operational and carbon costs associated with pumping and treatment at Crankley Point sewage treatment works