The Water Systems Division of Brockville, a city located in the Thousand Islands region of Eastern Ontario, Canada, serves more than 22,000 residents and businesses that call the city home, as well as a portion of the neighboring Township of Elizabethtown-Kitley. Its water treatment plant has a maximum design capacity of 36 Ml/day (million liters per day) and provides treated water through a system of approximately 130 km of underground pipes, which range from 100 mm to 600 mm in diameter and are comprised of various materials including cast iron, ductile iron, poly vinyl chloride, concrete, steel and asbestos cement.

(Originally published by Trenchless Technology. Click Here to read the article in original format)

A series of water audits found that the City’s non-revenue water (NRW) levels were between 15 to 20 percent. NRW is the difference between the volume of water supplied to the system and the volume of water billed to the customers. Simply put, it is water loss for which the utility receives zero revenue. NRW is an important issue facing water utilities, as it has a value of more than $18 billion per year worldwide, according to World Bank estimates.

The Water Systems Division began searching for a solution that it could use to reduce its NRW levels by accurately and efficiently detecting leaks in its water system.

Action Taken
After evaluating a number of different technologies, the Division purchased LeakFinderRT modules from Toronto-based Echologics and received training from the company’s engineers on how to properly use the technology to pinpoint leaks.

LeakFinderRT is a Windows-based leak detection system that is able to non-invasively detect underground leaks on water pipes — irrespective of their material, pressure, diameter, geometry, etc. It is based on recent acoustical developments that include an enhanced correlation function, which dramatically improves its ability to accurately identify and locate narrow-band leak noise that is characteristic of non-ferrous pipe material, low pressures, multiple leak situations, and excessive background noise created by traffic and other environmental factors.

The technology is non-invasive, which means it can detect leaks without breaking ground, inserting tools into the water system or disrupting service. While most leak detection methods require excavation or inserting hydrophones (water microphones) into the pipe, LeakFinderRT relies on standard pipe appurtenances such as hydrants, valves or direct attachments to the pipe’s outer wall. Surface mounted sensors are placed at two locations along the suspect water line—in most cases on valves or hydrants—between 120m and 1,300m apart. A correlator compares the acoustic signature of the leak with the expected speed of sound in running water; a computer algorithm then calculates the data to accurately pinpoint the location of the leak.

Results

Brockville’s Water Systems Division started using the technology in 2011, after its field workers received 1-on-1 technical training from Echologics. At the end of that same year, the Division conducted a water audit which found that more than 62,000 cubic meters of water had been lost through leaks and main breaks. Two years later, it conducted another audit — however, it found that the amount of lost water had been reduced by nearly 40 percent. The Division reduced water loss levels by pinpointing more than 30 leaks during the two years it has been using the technology.

“None of the leaks we detected were visible at surface grade, as the lost water was being absorbed by rock or flowing into sewers,” said Jason Barlow, chief water systems operator for the City of Brockville. “We estimate that roughly 75 percent of these leaks would have gone undetected if it wasn’t for the solution.”

The technology enables users to adjust filter settings according to different environmental factors affecting leak noise audibility. As a result, the Division was able to accurately locate leaks that would have been considerably difficult to detect using traditional leak detection systems.

This was apparent when workers used the technology to quickly pinpoint a previously unidentified service saddle leak on a 12-in. PVC pipe. The leak, which the Division suspects to have been present for years, was responsible for losing more than 200 cubic meters of water per day.

Additionally, leaks of all sizes were pinpointed on hydrant connections and water mains near busy roadways and intersections. Workers were able to adjust LeakFinderRT’s filter settings to differentiate leak noise from the high frequencies of noise created by traffic, which was regularly present in close proximity to the leak sites.

According to Barlow,  the Water Systems Division of Brockville is committed to providing a safe supply of potable water through the most efficient means.

“It is our responsibility to conserve water and energy and to protect Brockville’s water distribution system to the best of our ability,” said Barlow. “Not only do leaks waste treated water and energy, they threaten the distribution system with the possibility of contamination. Acoustic-based leak detection is a tool that helps us to fulfill our responsibility by enabling us to more accurately and cost-effectively identify leaks we would otherwise not find.”