Installing fibre optic cables inside drinking water mains could help the water industry reduce leaks and extend the life spans of its assets.
UK water companies have been challenged to halve leaks by 2050, compared to the 2017/2018 levels. Achieving that target will be hard because, according to regulator Ofwat, between 30% and 50% of leaks are very small and difficult to detect.
Existing leakage monitoring technologies are battery powered devices deployed for localised sensing. This means that some small leaks are not immediately detected.
Installing fibre optic sensing technology in drinking water mains could enable water companies to continuously monitor their networks and identify leaks in real time.
In 2021, the opportunity arose for UK water companies to explore this solution. The Department for Digital, Culture, Media & Sport launched the “Fibre in Water” competition for £4M of funding from the Treasury’s Shared Outcomes Fund.
The aim of the competition was to fund a pilot project focused on installing fibre optic cables in drinking water mains and to review the benefits for the water and telecommunications industries.
Strands of fibre optic cable were to be used to improve the ability of water companies to detect leaks, while telecommunications operators could take advantage of readily available ducts to decrease the cost of providing digital services and mobile telecoms coverage.
This could save considerable amounts of money as, according to consultant Arcadis, civil works to install new ducts and poles account for up to 80% of the cost of building gigabit-capable broadband networks.
UK trial
The Telecoms and Water Combined Operations (Tawco) project won the competition. Tawco was run by a consortium of four organisations: Yorkshire Water, Arcadis Consulting, University of Strathclyde and telecommunications networks provider CommsWorld.
The proposal suggested the deployment of fibre optic cables through 17km of live drinking water mains between Barnsley and Penistone in South Yorkshire, allowing Yorkshire Water to monitor this section of the network for leaks. CommsWorld would have then tapped into the same network to deliver connections to up to 8,500 homes and businesses along the route.
Arcadis senior strategic opportunities director Mark Harrop explains that this specific route was chosen because Penistone was unlikely to attract investment in fibre optic cable installation from commercial operators. It was also unable to attract state investment as part of Project Gigabit’s procurement lot for South Yorkshire. Project Gigabit is the £5bn government programme to facilitate the installation of fast broadband in rural areas.
Harrop adds that the Barnsley to Penistone route would have posed challenges for conventional broadband installation as it crosses highways and railway lines, as well as private land.
It’s quite an expensive solution. So you need a multi-sided business case and that’s why you need telecoms companies involved
The £2.3M Phase 1 of the project was the research and investigation stage, where operational and commercial models were developed, while detailed route survey and build costs were completed along with a commercial assessment of the chosen route’s revenue potential.
Even though aligning the commercial and operational interests of the telecommunications and water industries was challenging, Harrop says the necessary models were developed. However, the project failed to reach Phase 2 – the detailed design and build phase.
All materials and equipment installed within the clean water network must obtain a Regulation 31 approval from the Drinking Water Inspectorate, which requires proof they will not affect water quality.
For this project, approvals were needed for the installation method and the finished installed product. According to the Tawco Final Public Report published in January, the approval for the finished product is still pending, so the trial could not proceed to Phase 2.
In addition, Harrop says the uncertainty about the inclusion of Peniston in the Project Gigabit lot impacted the telecommunications company’s appetite to invest.
Talking about the lessons learned from this project, Harrop says that unless it is a “massively critical asset with limited resilience” there is no economic case for a water company to invest in this solution solely for leak detection. “It’s quite an expensive solution. So you need a multi-sided business case and that’s why you need telecoms companies involved.”
One of the key cost drivers for this solution identified by the project team is the cost of circumnavigating valves on the chosen pipe route.
For the valves along a route to operate properly, the fibre must be extracted from the pipe before the valve and reinserted after it. The report states that in urban areas there are typically three valves per kilometre, which would increase the cost and complexity of installation.
Technology
With the UK trial coming to a halt, the water industry is falling behind some of its European counterparts in testing fibre optic technology for leak detention.
A fibre optic pipeline monitoring system called Dali has been developed by fibre optic sensing provider Fluves and fellow Belgian piping systems specialist Vigotec.
It has been trialled in several countries including the Netherlands, Belgium, France and Sweden.
“Dali can be used both for permanent monitoring and short term leak detection,” says Fluves project manager Thijs Lanckriet.
The system is in several parts. “We have a fibre optic cable which we insert into the pipe. Once a fibre optic cable is in place, we connect it to a distributed acoustic sensor (DAS),” says Lanckriet. The sensor covers up to 70km in multiple directions.
A DAS, connected to one end of the fibre, uses a laser to send short pulses of light along it, creating a unique pattern of reflections. Vibrations from the environment disturb this reflection pattern in the pipeline and these optical signals return to the DAS system for analysis.
“We have also developed software to process these raw measurements into algorithms to detect leaks but also intrusions such as unauthorised digging activity,” says Lanckriet. A real time online dashboard displays the pipeline status and sends notifications to Dali users when there is a suspected leak or intrusion.
The cable has a polyethylene outer mantle and there are two versions, one that can accommodate 12 fibres and one able to accommodate 144. “For the monitoring, we only need one fibre,” Lanckriet says, pointing to the capacity available for water companies to lease fibres to telecom operators.
The cable can be installed using existing access points such as hydrants or air valves or by creating new access points on the pipeline.
Custom fittings are used for the cable to be inserted into the pipe, with a parachute system pulling the cable to the point where it is extracted. When there are valves across the route being monitored, access points are created to bypass them.
Objectives and results
Belgian water company Farys, which distributes potable water to 1.2M customers through a 660km pipeline network, is among the companies testing the Dali system.
“On our system we have about 10 to 20 spontaneous leaks a year. Most are quite small with very low repair costs and cause no damage to the environment. But every few years we have a big burst which can cause a lot of damage and cost hundreds of thousands of euros,” says Farys innovation director Wim Jacobs.
He says the main benefit of this technology is the continuous monitoring of the assets and the ability to pinpoint the locations of small leaks that do not reach the surface. Some of the pipes on Farys’ network are 100 years old and the company believes the technology, if proven efficient, could postpone their replacement.
“The reason we are doing it [trialling this technology] is not really about water loss but more for expanding the lifetime of the system and avoiding the big bursts on transport pipes,” says Jacobs.
We were able to find leakages from around 500 litres/h
Dutch water company Evides decided to test Dali because it anticipates an increase in leaks as its system gets older. Peter Schaap who coordinates all of Evides’ research, identifies its ability to detect smaller leaks as the main potential benefit of this technology.
He says that sometimes the leaks are so small – between 2m3/h and 3m3/h – they have no impact on pressure. This water often flows directly into a watercourse, making the identification of leaks difficult. “If that goes on for a couple of months, there’s a lot of water wasted,” Schaap stresses.
He adds that another benefit could be the use of data generated to demonstrate the need for pipe replacements.
Evides tested Dali at the external above ground pipe network at the KWR water research institute in Nieuwegein in the Netherlands. The tests focused on installation, hygiene and leak detection performance.
Dutch water company Evides tested Dali at the KWR water research institute (Credit: Evides Waterbedrijf/ Photo: Michelle Muus)
Stefan Knijnenburg, project leader for Evides’ “Network for the future” research programme, says small holes were created in the pipes to investigate the volume of leaks detected. “We were able to find leakages from around 500 litres/h,” he says.
He expects the system’s ability to detect leaks would be greater in real conditions because sound is more isolated underground and holes are asymetrical. Evides is planning to test the technology within its own network later this year.
Farys installed the technology in 6km of pipeline in 2020 but Jacobs says the results have been mixed.
“We had a leak and the water was coming out on the surface. Dali didn’t record anything suspicious on that location but recorded something 100m further away. The leak was in fact 100m away and the water travelled under a road. In this case it proved to be quite efficient,” says Jacobs. “On the other hand, we had a small leak which wasn’t heard by the system.”
Last year, due to a water hammer incident – a pressure surge occuring when a shock wave travels along a main due to a sudden, short-term change in water flow rate – Dali is currently active on 800m out of the 6km. Jacobs says more testing is needed before rolling it out to the entire network, with the company planning to install the system on a further 14km.
“The most objective validation of the system so far was with Vitens, the largest water company in the Netherlands,” says Lanckriet.
Seven artificial leaks of different sizes on a 500m long test pipe were created by Vitens.
Lanckriet says the system pinpointed the leak locations and successfully estimated their size.
In terms of fibre optic cables’ impact on water quality, Lanckriet says a test conducted by Swedish water company NSVA showed there was none.
As more trials of this technology are carried out and the pressure to cut leaks increases, it may not be too long before we see fibre optic cables installed in UK water mains.
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