BACKGROUND
Ens d’Abastament d’Aigua Ter-Llobregat (ATL) is a public company of the Government of Catalunya, attached to the Department of Territory and Sustainability whose mission is to produce and supply drinking water to the population through transport and distribution networks, as well as to execute, maintain, conserve and manage the facilities that make
up the entire network.
ATL supplies drinking water to more than 100 municipalities in the regions of Alt Penedès, Anoia, Baix Llobregat, Barcelonès, Garraf, Maresme, la Selva, Vallès Oriental and Vallès Occidental, which represents a population of around 5 million inhabitants.
The supply network managed by ATL has more than 1000 kilometers of pipes, more than 60 pumping stations and a surface area of 1800 km2.
PROBLEM RAISED
In 2015, ATL performance reports showed a loss of flow. Once the appropriate checks were carried out and the derivations in the Vallés Occidental regional conduits were discarded, a net loss due to non-visible leakage of approximately 6.07 m³/h was calculated.
These leaks were immediately searched for using conventional systems: pressure tests, correlation, accelerators and hydrophones. The application of these systems did not allow the location of the anomalies mainly because the section runs through urban areas with high traffic density with the consequent external noise.
The possibility of using tracer gases was assessed, but, given the lengths of the two sections to be inspected (5,799 ml in total) and its large diameter (Ø800m Ø1250mm), the application of this method was shown as an option that greatly raises the cost of the process, while posing risks of not being able to deliver the expected results.
Using wired devices was also evaluated as it had been effective on other occasions. But considering the length of the section to inspect and the maximum reach of these devices, (1 – 1.5 km) it did not seem to be the suitable method. Given the situation, ATL opted for the application of the Nautilus System, a wireless neutral buoyancy technology specifically designed for the inspection of large diameter pipelines.
SYNCHRONISATION
Three synchronisation points were installed along each section with a distance of 750m between them. These synchronisation points are used as a reference for Nautilus for the exact location of the leak points.
RESULTS
Once the information collected in both sections was analysed, the final report showed the existence of two leaks, one anomaly and their exact location in the inspected section. Once the location of the leaks was confirmed, the ATL technicians proceeded to carry out the corresponding openings at the two marked points to proceed with their repair and, consequently, recover the flow rates of maximum use of the network.
After receiving the inspection final report, we decided to repair those leaks. When we began the repair work, we found the leaks at the exact points indicated. As a reliable system, we have incorporated the Nautilus System into our catalogue of leak location systems with fully satisfactory results to date.
-Client Testimony
