Water Leaks – a Sign of Aged Assets

Much of our pipeline infrastructure for transporting and distributing raw water and potable water is nearing the end of its useful life.? In 2002, the AWWA published an article stating that pipelines that were manufactured prior to WW2 had a design life of 100 years. Due to changes in manufacturing, the design life post WW2 was reduced to 50 to 60 years.? As such, based on the infrastructure build-out, many of the pipelines will, or have reached the end of their useful life. In a 2001 publication AWWA stated “pipelines are expensive, but invisible”, and furthermore, that buried pipelines are “out of sight, out of mind”.

Leaks are one of the signs of pipeline degradation.? Leaks represent 10% to 15% of water loss. This is an ever-growing problem that has prompted new and innovative inspection technologies. A quick summary of inspection technologies used to identify and locate leaks are listed below. ?

Visual Inspection: While less common in large-diameter pipes due to their inaccessibility, visual inspections may still be employed in certain sections of the pipeline accessible through manholes or inspection chambers. This method includes visible wet spots in the ground near the leak, to a large leak bubbling or shooting out of the pipeline.

Dogs: There is a growing use of trained dogs to locate places that have the “scent” of residual chlorine. ?

Pressure Monitoring: Monitoring pressure changes within the pipeline can indicate the presence of leaks. Sudden drops in pressure may suggest a leak in the system. Pressure sensors placed strategically along the pipeline can help identify these variations.

Flow Monitoring: Flow meters measure the flow rate of water in the pipeline. An unexpected decrease in flow rate can indicate a leak. By comparing expected and actual flow rates, leaks can be identified.

Satellite Imagery: Remote sensing techniques using satellites can detect anomalies such as wet spots or vegetation stress caused by underground leaks. These methods provide a broader overview of potential leak locations over a large area.

Thermal Imaging: Thermal cameras detect temperature differences caused by leaking water. Underground leaks may result in localized temperature changes that can be captured by thermal imaging cameras mounted on drones or other platforms.

Acoustic Sensors: These sensors detect the sound of leaks through the pipe walls or vibrations caused by escaping water. They are deployed along the length of the pipeline, locating leaks based on the intensity and frequency of the sound. This method of locating leaks is widely used due to its level of accuracy and ease of use.

Tracer Gas Injection: Tracer gases such as helium or hydrogen are injected into the pipeline. Sensors at ground level can then detect these gases as they escape from leaks, pinpointing the location of the leak.

Data Analytics and Modeling (AI): Advanced data analytics and modeling techniques can analyze data from various sensors and sources to identify patterns indicative of leaks. Machine learning algorithms, for example, can be trained to detect subtle changes in pressure, flow, or acoustic signatures associated with leaks. As the AI models are refined and the computing power increases, a strategically laid out sensor network will be able to locate and qualify or rank leaks.? This can start to move us in the right direction toward “zero tolerance to leaks”.

Pipeline Inspection Gauges (PIGs): PIGs are devices that travel through the pipeline, inspecting its condition and detecting anomalies such as leaks, corrosion, anomalies and blockages. They carry various sensors, including ultrasonic testing (UT), circumferential scanning sensors, hydrophones and internal mapping unit (IMU) to detect leaks. Recent in-line inspection technologies provide wall thickness measurements, ID changes, precise pipe geometry, joint defects, leak and air pocket detection, pipe ovality, delamination, AC leaching, and plots XYZ coordinates of the entire alignment.

Leaks signal deteriorating assets, warranting proactive identification of potential leakage points. Conducting in-line inspections emerges as the optimal approach for pinpointing current and probable leak locations. Leaks can occur along a failing pipeline, but most occur at the joints. The three main failures in joints that cause leaks are:

• Corrosion and degradation (metallic joints)?
• Deflection: Caused by soil movement or improper installation
• Gap width: Caused by differential thermal expansion and contraction, soil movement, or improper installation.

Water is an invaluable natural resource, and the pipelines that deliver water to communities and businesses are a valuable asset. Leaks indicate a pipeline in decline. Employing any of the methods outlined can lead to a decrease in leaks. Proactively managing these assets ensures their role in water distribution without loss. A proactive asset management program gives asset owners the ability to make informed decisions related to the replacement, repair and rehabilitation of critical buried assets based on specific, high-resolution field inspection data and comprehensive assessment work.