Pipe specialist delivers environmental and cost savings for super sewer project

Lancashire manufacturer, Aquaspira, has delivered a super sewer project solution which will save 234 tonnes of carbon.

The Nelson-based company has designed and manufactured 520 metres of reinforced steel composite pipes as part of the upgrade to a critical section of the Perth sewer network, needed as the Scottish city is set to grow by 50%.

Usually built using concrete pipe for strength, the manufacture and transport of these would generate significant carbon emissions. Instead, Aquaspira’s high strength, reinforced steel pipe has reduced product mass over a more traditional concrete solution by more than 5,000 tonnes.

The smaller size, coupled with this ultra-lightweight solution, has decreased the amount of excavation required by 28%, dramatically lowering the environmental impact by reducing fuel consumption and needing fewer vehicle movements to and from site.

The lightweight composite pipes have also enhanced site safety and reduced site installation time by approximately eight-10 weeks.

Aquaspira was appointed to the prestigious Scottish drainage project, which started in May 2023, by Scottish Water’s capital project delivery partner Caledonia Water Alliance.

A spokesperson for Caledonia Water Alliance said: “We specified the Aquaspira pipes and access units because it would provide a lower carbon solution, minimise the footprint and shorten programme time.

“An accredited and adoptable solution is vital and Aquaspira provides this, the added benefit is that the 2.6 metre sections of pipe, coupled with the push-fit access solution, help with the ease of installation.”

The project will see the installation of new sewers to manage the expected 50% growth in Perth’s population, particularly to the north and west of the city. It will also manage flood risk by improving the network’s resilience to, and capacity for, intensive rainfall, particularly in the low lying areas near the River Tay between Muirton and the city centre.

Following extensive survey and modelling work carried out by Scottish Water, in partnership with Perth & Kinross Council, the £107m infrastructure investment is now under way and the Tay Street and Shore Road Sewer upgrade with the new ‘super sewer’ is one of the key projects. It is set to complete in January 2025.

Scottish Water’s Senior Project Manager, David Lavery, said: “While we are adapting our infrastructure to a changing climate, we also need to play our full part in addressing its causes. Scottish Water has set a challenging target to go beyond net zero emissions across all of our work by 2040, including the delivery of our significant investment programme. Finding lower carbon ways to build new infrastructure is a crucial part of that journey.”

He added: “Modern sewers of this scale would ordinarily be built using concrete pipe to achieve the required strength, but manufacturing and transporting these across long distances generates significant carbon emissions. The composite steel pipe being used has a lower carbon cost and is much lighter, while having higher strength than could be achieved using plastic pipe at this scale.”

Mark Stanway, Director at Aquaspira, said: “As well as providing technical support, design optimisation and provision of information to enable a detailed carbon evaluation, we also ensured the installation team was fully briefed on all aspects of the installation process working closely with the site manager to establish delivery schedules to suit the programme.

“In addition to the 2.25m diameter steel-reinforced pipes, our solution also includes prefabricated access units. These push-fit solutions reduced the installation of each manhole from an average of four days to around an hour, delivering dramatic cost and time savings to the job, as well as providing a far more environmentally friendly and safer solution.”

He added: “Ultimately, we reduced the number of vehicle movements to site by over 65%, as well as cutting the amount of bedding and backfill. The project is now running ahead of programme, partly due to the installation efficiencies of the pipe and access units, helping to reduce disruption for the local community.”

Aquaspira is working with the University of Birmingham to develop a digital twin to improve design and to investigate the use of recycled materials for backfill to further reduce carbon usage in the construction sector and use sensors in pipes for long term monitoring and maintenance.

This research can make a huge step change in helping the construction sector achieve government de-carbonisation targets.