Water Journal : Water Journal April 2014
197 Water Business pipe quickly and accurately, pinpoint faults and, more importantly, assess how critical they are? If they can do this they will be able to apply targeted xes. And, instead of making expensive, large-scale replacements based on age, these will be able to be made on pipe performance. There is the potential to shift from a reactive, age-based maintenance model to a proactive and preventative one. This is where the opportunity lies for real cost savings to consumers. A new bre optic system developed through a collaboration among Melbourne Water, Monash University, South East Water, CSIRO Land and Water and Hawk Measurement Systems has the potential to provide 24/7 monitoring, accurate and inexpensive fault and deterioration location, and reduce unnecessary pipe maintenance. Trials to date indicate the system is accurate to within one metre along 50 kilometres of pipe. Choosing to work with numerous partners on this project put Melbourne Water in a position to gain industry support and to successfully obtain funds from the Victorian Government. A signi cant grant from the Department of State Development, Business and Innovation's Market Validation Program, along with cash and in-kind contributions, has resulted in a $2.5 million project. Existing bre optic sensing technology was known to have the capability to monitor the condition and integrity of pipes, but available solutions were largely con ned to those above ground. What was needed was a system that allowed sensors to be installed and managed on buried pipes in a cost- effective manner for the long service life of water pipelines -- up to 100 years or more. Traditionally, leaks need to become visible rst. They are then located with a stethoscope-like instrument, which requires a site visit. This observation can be drawn out, as leaking water often appears at the surface some distance from the actual pipe fracture. With the newly developed bre optic system, once a fault is identi ed it can be evaluated remotely using a data acquisition system that can sense three signi cant variables -- stress and strain (or pressure), sound vibrations and temperature. A laser beam is sent to the optical bre, which measures the signals coming back. Analysis of the spectrum interprets the signals, telling the operator what kind of fault is occurring, its location and dimensions. Continuous long-term remote monitoring using bre optics eliminates the need for onsite inspection either to monitor pipe health or to detect leaks. All the sensed variables are constantly monitored and 'sensed area' accuracy is approximately 0.5 metres over 50 kilometres of installed bre. The multiple analysis system eliminates the possibility of false positives from a single signal. Chair of the Project Control Board, Professor Jayantha Kodikara, head of Geotechnical and Geoenvironment at Monash University's Department of Civil Engineering, says that to his knowledge this is the first three-in-one, remote measurement system available. "There are remote systems that measure strain and temperature, but not acoustics," he says. "The value in acoustics is that you can hear leaks along the pipeline long before they become breaks." Attaching the bre optic cable to the pipelines has thrown up practical obstacles: how to attach the cable to a pressurised pipe (inside or outside?), and how to deploy the bre optic cables so they can be renewed in future, as they may not last as long as the water pipeline. The solution developed by Hawk allows the cable to be installed in one-kilometre sections of conduit attached to the wall of the pipe. The system can be buried underground or under water. An installation can be both replaced and upgraded, making it ideal for infrastructure with a long service life. The project has made links with Intelligent Water Networks and with Integrated Water Management Systems, which suggests bre optics could be a tool for them to use. Learnings from this project will undoubtedly inform future discussions among scientists and engineers. Dr Hong Chun Bao at the Hawk Photonics Laboratory making adjustments to the Erbium Doped Fibre Ampli er.
Water Journal February 2014
Water Journal May 2014