Assessing the condition of buried water infrastructure can yield a variety of outcomes that are difficult to predict. Sometimes, they even seem random.
The common belief that the age of a pipe determines its condition is rarely correct – in many cases, a newer main can be in worse condition than one twice or three times as old. Instead, operational, environmental and installation factors have more impact on the condition of a buried asset.
For utilities embarking on proactive management and assessment of their buried infrastructure, leak detection is a logical starting point. Reducing water loss by repairing leaking pipes provides immediate return on investment by lowering Non-Revenue Water. In addition, it provides a valuable pre-screening to a more detailed condition assessment.
For Metropolitana Milanese (Milan, Italy), this is precisely where they started with one of their 1200-millimeter (48-inch) steel transmission mains.
The critical Rincera Perdite Transmission Main was installed in 1982 and had never been assessed. While this main is not particularly old, Metropolitana Milanese decided to proactively assess 9 kilometers (5.5 miles) of the pipeline using the SmartBall inline leak detection tool.
The tool is a free-flowing leak detection platform that operates while the pipeline remains in service. It is capable of completing long inspections in a single deployment and is equipped with an acoustic sensor that identifies acoustic anomalies associated with leaks and air pockets; the acoustic signature is then analyzed to determine if it is a leak, air pocket, or an external noise.
Identifying leaks small or large contributes to maintaining the condition of a transmission main. In metallic pipe materials, a catastrophic failure is often preceded by a period of leakage, so identifying and repairing leaks can help to reduce water main failures.
Metro Milan Identifies Large Leaks
Through the use of inline leak detection, Metropolitana Milanese identified 23 large leaks on this 9-jilometer stretch of transmission main. One section of the main had a concentration of leaks, with 8 leaks in a stretch of 240 meters (800 feet).
By determining the specific locations of leaks on the Rincera Perdite Transmission Main, Metropolitana Milanese will be able to reduce its NRW and has gained a better understanding of the overall condition of the pipeline. This will aid in future capital planning and will also provide a valuable study into determining the external factors that might be causing the leakage.
Focused repair works for the leaks will allow the utility to extend the life of the pipeline and reduce water loss, thus improving the overall service to its customers. The final data from the inspection will be presented in an innovative asset management viewer to Metropolitana Milanese.