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York Region Manages Risk On Critical Water Main Nrw

For water service providers, providing customers with consistent, reliable access to clean water is crucial. In densely populated urban areas, such as the Greater Toronto Area (GTA), this often requires operators to manage and assess pipelines that cannot be removed from service, yet provide water to a large number of end-users.

In April 2013, The Regional Municipality of York, in conjunction with the Regional Municipality of Peel and the Ontario Clean Water Authority (OCWA), assessed the condition of the York-Peel Feeder Main, which stretches roughly 25 kilometers, (18 km in York Region and 7 km in Peel) through both Regions. The pipeline is made of 1800-mm (72-inch) Prestressed Concrete Cylinder Pipe (PCCP) and provides a crucial supply of water to residents and businesses in York Region.

In spring 2014, York Region repaired three leaks found through a prescreening survey and verified the condition of one pipe section showing signs of structural deterioration identified through electromagnetic (EM) inspection.
Identifying leaks in large-diameter transmission mains is important in reducing Non-Revenue Water (NRW) – which can be defined as water that is produced for consumption and lost before it reaches the customer. Reducing NRW helps eliminate waste and contributes to the conservation of a crucial natural resource.

In addition to the environmental benefit of reducing water loss, eliminating leaks plays an important role in pipe integrity. The presence of leaks often indicates a potential failure location and by identifying leaks, utilities can reduce pipe failures and gain a better understanding of the overall condition of their system.

For its prescreening survey, York Region used SmartBall® technology, which is a free-flowing tool that identifies the sound of leaks as it travels through a live, operational pipeline. In total, the prescreening survey identified seven anomalies that resembling leaks. Four of these leaks were matched up with existing pipeline features while the other three were verified and repaired by York Region. One of these leaks was located on a 1200mm, high-pressure line running adjacent to the 1800mm line.

While prescreening and leak detection is an important part of condition assessment, critical large-diameter transmission mains warrant a more detailed inspection to identify areas of structural deterioration. By doing this, utilities can identify specific pipe sections that are at risk of failure before they rupture.

Although inspection shows that a large percentage of pipe sections have no deterioration at all, eliminating the risk of one failure can be very beneficial, since the typical cost associated with a large-diameter pipe rupture is between US$500,000 and US$1.5 million, not including the reputational damage a failure can cause.

To identify distress in its PCCP transmission main, York Region completed a non-destructive EM inspection using PipeDiver® technology. PCCP is a concrete pipe that remains under compression because of the prestressing wires, with the thin-gauge steel cylinder acting as a water membrane. As the prestressing wires in PCCP begin to break, the pipe becomes weaker and is more likely to fail catastrophically. It is important to locate and quantify the amount of broken wires in PCCP as they are the main structural component.

When assessing PCCP, PipeDiver technology locates and quantifies the number of broken wires. This method is extremely effective in identifying pipe sections that should be target for renewal once the number of wire breaks passes a certain limit.

The inspection covered 4,280 pipe sections and identified 17 pipe sections that had signals indicative of wire break damage. This represents less than one per cent of the feedermain, meaning the asset is in very good condition. York Region accurately verified the condition of one section of pipe with an unacceptable amount of wire breaks.

A portion of the project also used the condition assessment data to complete detailed risk analysis that will provide York Region with a better understanding of how their pipes perform. This allows for the development of a baseline condition of the entire transmission main and aids the development of long term management, renewal and re-inspection plans.

Although this pipeline was constructed in 2005 and is relatively young, the condition assessment was completed proactively to ensure the continued safe operation of the asset. Managing risk through proactive condition assessment is an excellent tool for operators of large-diameter pipelines. The York-Peel Feedermain conveys roughly 165 million liters per day and in time, will achieve a maximum capacity of 380 million liters per day.

 

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