Process and control today | Leak test in Ovarro-Northumbria reaches night line target

18/09/2024 Ovarro

Northumbrian Water, which supplies water to 2.7 million people in the north-east of England, is targeting an 8% reduction in leakages in its AMP8 programme (2025-2030), with a long-term goal of a 55% reduction by 2050, from a 2017/18 baseline, writes Paul HoltSpecialist in leakage products from Ovarro

The company’s revised draft Water Resources Management Plan 2024 says innovation is key to achieving its goals, and the company also promises to make its network smarter using new technologies so leaks can be detected faster.

For this reason, Northumbrian Water is carrying out a series of feasibility studies and trials ahead of AMP8, including one with Ovarro. The results will inform future investments and leak detection strategies.

The solution

In November 2023, Northumbrian Water partnered with technology company Ovarro to trial LeakNavigator, an end-to-end fixed network leak detection service. The three-month trial covered the Fish Quay District Metered Area (DMA) in the town of North Shields, which supplies nearly 1,400 homes via 17km of water mains.

Northumbrian Water has set itself the objective of achieving a historic night-time minimum of 7.6 m3/h for the trial and will maintain this value after completion of the project.

The LeakNavigator package includes a fully managed analytics platform, acoustic data loggers from Ovarro’s Enigma range and access to their in-house leak expertise. The service identifies points of interest (PoIs) on behalf of water utilities and notifies field engineers directly via a mobile app, reducing the need for in-house data analysis.

LeakNavigator’s end-to-end service includes an upfront assessment of the targeted DMA by Ovarro’s leak analysts, as well as ongoing data analysis once the loggers are in operation.

For Northumbrian Water’s trial, 36 loggers were installed, a combination of Enigma3-BBs and Enigma3hyQs. Both models are correlated acoustic loggers fitted with a sensitive hydrophone sensor to measure the sound generated by leaks, which typically occur overnight, and feed data into the analysis system.

The Enigma3hyQ is typically installed on a fire hydrant or valve. The Enigma3-BB is installed on a property meter box chamber, simplifying the process as meter boxes are easier to reach than fire hydrants. It also provides more network access points to the network, increasing logger coverage.

The loggers were chosen for their ease of use and proven ability to find leaks in plastic pipes – a constant challenge for water utilities as sound does not travel well on plastic pipes. As more and more aging metal pipes are replaced with plastic pipes, this challenge will only increase.

During the first week of the trial, when PoI follow-up investigations did not reveal the expected number of leaks found, Ovarro organized additional training for technicians. Engineer Paul Holt spent two days on site, closely guiding the Northumbrian Water team through the end-to-end LeakNavigator process. After the training, technicians discovered more leaks much more quickly.

Results

During the trial, five major leaks were found with a conversion rate of 80%. Among them was a large leak on an 8-inch (203 mm) PVC water pipe.

Northumbrian Water’s normal DMA detection techniques failed to find the leak, which is estimated to have been present for around 12 months. Flow data shows that at least 5.5 l/s of water was lost through the leak, which equates to 475 m3/day, and would amount to 171 megalitres over 12 months.

A second large leak was discovered on a commercial customer’s private line. After both leaks were repaired, the nighttime performance target was achieved and maintained from July 2024.

Andrew Blenkharn, Northumbrian Water’s technical policy manager, said: “The aim of the Ovarro trial was to see what options we have to reduce leakage in AMP8 and to investigate the feasibility of permanent logging. For us, the technology was quick to deploy and has been proven to work, delivering excellent results.

“I was particularly impressed by the discovery of the large leak in the PVC main line, which would not have been discovered otherwise. The leak had been occurring in this area for some time and had not been detected using normal methods.

“Overall, we achieved the historical minimum we were aiming for and were confident that if the loggers had remained in use, we would have been able to respond quickly to future leaks.

“As leaks become increasingly difficult to clean up, permanent clearance, particularly of plastic, becomes a viable option for the future. For Northumbrian Water, leaks will continue to be a major issue and this is just the start of our efforts to reduce levels in AMP8.”

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