Leak detection is a key use case for the smart water network with acoustic leak detectors a supplement to district metered areas.
The electricity smart grid has attracted much publicity as smart meters and subsequently other smart technologies have brought intelligence and automation to the distribution and transmission systems.
Though not so high profile, the water networks are no less significant in need of being ‘smartened’.
Smart water metering is one key technology. While water meter reading requirements are not so stringent as electricity and demand management is not generally a requirement, smart water metering is no less important in securing regular and accurate readings for billing and eliminating the need for physical meter reading.
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Prepayment is an option for customers and changes of property ownership can be handled remotely with remote switching.
Smart water metering also could leapfrog the basic metering in the many locations still without, where billing is not based on usage but another factor such as the property value or size.
Then there are the ‘smart grid’ technologies for monitoring and management of the water networks. Pressure and flow measurement are among useful tools. Elsewhere in the system, water quality monitoring can be deployed.
But arguably one of the most fundamental is leak monitoring, with water lost to leaks, and hence to revenue collection, averaging around 30% globally.
“Such technologies have the goal of enabling operational visibility into the health of the distribution system as well as helping utilities improve their operational efficiencies through effective and targeted water loss reduction,” says Sheila Kee, Senior Product Manager Water Operations Management at Itron.
District metering areas
Traditionally leak detection for water and also gas has been based on district metering areas. A service territory is divided into ‘districts’ and in essence, the metered flow into and out of the districts is compared with the metered volume to the properties within the district, with a difference indicative of a leak.
This district metering approach has been implemented at the southern Kentucky Warren County Water District since as far back as the 1980s, long before it became widely implemented.
However, when the company, which also manages the neighbouring Simpson County Water and Butler County Water districts, came to audit the losses, it felt an additional approach was needed.
“Although our infrastructure leakage indexes suggested we are in good shape, a different story is painted when the cost of the water is applied to the losses,” said BJ Malone, Manager of IT/GIS at Warren Water and project lead of the AMR/AMI implementation in a presentation at Itron Utility Week EMEA in March.
“Together the cost to the three systems is approaching $900,000 and for example for Simpson the losses amount to almost 20% by volume and 10% of the operating budget.”
Together, the three counties have about 3,300km of transmission and distribution lines, 380km of service lines and 280km of collection lines serving over 39,000 water and 7,500 sewer customers over a 3,100km2 area. Across the three areas, approximately 600 leaks have been detected each year.
While district metering has obvious efficacy, a challenge is that if a leak is suspected technicians often have to work through the area to locate it, which can take time and resources. A further specific challenge with the Warren County area is that with its Karst topography, drainage from leaks can be downwards rather than to the surface.
Acoustic leak detection
While pipe replacements had been implemented, Malone says that when Warren County started to implement AMR/AMI with Itron in 2018, it also started to investigate acoustic leak detection.
After a six-month pilot, full-scale deployment was initiated, with over 18,000 Itron AMR and AMI endpoints and almost 11,000 Itron Riva leak sensors now in the field.
“At this point we’re off to the races,” says Malone, noting that the locations of the leak sensors have been optimised with GIS.
Data analysis is via an online platform, with data from all sensors uploaded daily and mapped with colour coding according to leak probability for easy visualisation.
“In addition to the main and service line leaks and being able to zero in more quickly on the location of the leak which we expected, we also have had some unexpected results,” Malone says.
“One of these is detection of customer side leaks, which we wouldn’t normally pick up on the meter due to the low flow. The other is busted meter bottoms and this is particularly important now with AMR/AMI that meter readers aren’t opening the boxes and looking inside regularly.”
With the system over the past year on average 11 service line leaks per month were found, with volumes ranging from just over 2l per minute up to 140l per minute with an average almost 50l per minute.
“For us acoustic leak detection is an enhancement to our established district metering areas in enabling us to find and repair more leaks in less time,” Malone concludes.
“We feel we have done well and expect the water loss improvements to increase as we complete the rollout over the next couple of years.”