Reducing the amount of water used in pipeline commissioning

Anglian Water’s new strategic pipeline is a fundamental part of its Water Resources Management Plan. The Strategic Pipeline Alliance (formed of Costain, Jacobs, Mott McDonald Bentley and Farrans) is enabling the efficient delivery of Anglian Water's physical assets. This includes an ambitious plan to create a series of up to 500km of interconnecting pipelines and associated infrastructure to move water from areas of surplus in Lincolnshire down to the drier south and east of the region. Without taking this action, the East of England would face a water deficit of 30 million litres a day by 2025.That’s a shortfall of 4,380 Olympic swimming pools of water every year.  

Using traditional commissioning methods for the new pipeline would require c.1.5 billion litres of water. Given that the SPA pipeline is being created to mitigate the long term supply/demand balance, using significant volumes of water during construction and commissioning is fundamentally at odds with the purpose of the project. Applying conventional commissioning would also impact the environment through large discharges, higher pollution risk and added carbon through extra water production, lagoon construction and programme time. 

The SPA solution was to look at a wide range of commissioning options. A completely waterless solution is not possible as water is required for water quality sampling before the pipes go into service. A low water commissioning approach was devised, which uses a fraction of the water previously needed, while still maintaining the crucial food hygiene standards within the pipes. 

Traditionally, commissioning would mean swabbing and flushing vast amounts of heavily chlorinated water through the pipes, meaning a 1km length of 700mm diameter pipe would need about 380,000 litres of water to clean it - enough to fill 3,800 baths or one and a half Olympic swimming pools. LWC uses a fraction of that water, by using compressed, dry, and clean air to drive slugs of water between swabs to clean and disinfect the pipes, meaning cleaning the same 1km length of pipe would need 190 baths of water instead of 3,800. 

Two trials have taken place, the results from which led to the creation of a low water commissioning strategy. The trials showed water savings of 85%, but it is forecast that savings could be as high as 95% if learnings from the trial are implemented. 

 

*Main photo credit: David Clarke/Sky Cam East Lincolnshire