Corrosion often occurs on assets that are out of sight, such as buried water pipes or reinforcement within structures, and failure to detect and manage corrosion can cause irreversible damage to these assets. Melbourne Water, one of Victoria’s largest water authorities, has a number of strategies to manage and mitigate corrosion across its water and sewer networks.
Melbourne Water owns large and complex infrastructure which provides essential services and benefits to more than five million Melburnians.
Mark McLean, Area Lead – Transfer, Water (Civil) Asset Management, Asset Management Services at Melbourne Water, said that corrosion protection is a vital part of any asset management strategy.
“Management and mitigation of corrosion is seen as a core function of asset management and maximising asset life for Melbourne Water to ensure the least community cost of maintaining and operating our assets.”
Abhi Sulur – Acting Team Leader, Civil Sewerage Asset Management at Melbourne Water, added that it is important that whole-of-life costs are kept to a minimum and that return on investments are maximised.
“To achieve this, robust asset management practices will need to be in place to manage the lifecycle costs. Failure to do so could potentially result in; increased risks associated with asset failures; failure to meet levels of service and obligations to customers; and an increase in whole-of-life costs as a result of significant renewal costs brought forward to manage the risk,” Mr Sulur said.
The integration of digital technologies is also playing a role in Melbourne Water’s successful corrosion management.
“The use of Ground Penetrating Radar has proven to be a valuable source of information around corrosion. The technology is improving and is becoming cost effective,” Mr Sulur said.
“Use of GPS information has also improved and assisted in data collection for condition monitoring, as well as assisting in finding buried corrosion assets. Melbourne Water has also started using new remote data loggers to reduce the frequency of attending sites and improve the ability to obtain instantaneous data remotely,” Mr McLean commented.
Understanding the impact of corrosion on water infrastructure
Melbourne Water continues to improve its corrosion protection on every structure with metallic materials (steel pipes, steel main, concrete with rebar, pumps) through use of corrosion protection systems, barrier coatings and appropriate material selection.
The utility is also heavily involved with the Victorian Electrolysis Committee on mitigating stray traction corrosion caused by electrified train and tram networks.
“Material and coating selection are critical, as is jointing and electrical continuity for our pipelines and structures when constructing new assets. Cathodic protection systems are the main criterion when building new assets which contain metallic components,” Mr McLean said.
“For all of our metallic pipeline systems and some reinforced concrete structures, we use a combination of Impressed Current Cathodic Protection (ICCP) and Sacrificial Anode systems, and insulated flanges to allow for discrete management of our assets. These are being installed across Melbourne Water assets to mitigate the corrosion related issues.
“An IoT monitoring system is also being installed to monitor ICCP systems to improve the response time to these systems operating outside of desired output ranges.”
Investigation into corrosion related issues, such as coating defect surveys and direct current voltage gradient methods, is key to ensuring an effective corrosion protection regime is in place as part of the commissioning process.
Mr McLean said that Melbourne Water recently installed a new Hybrid Anode Cathodic Protection system on 7km of a reinforced concrete retaining walls system.
“The installation was completed in December 2017 and currently is in the commissioning stage. Melbourne Water is intending to continue to monitor its performance as part of an ongoing trial to maximise the system’s effectiveness and refine how these types of systems can be efficiently installed and maintained,” Mr McLean said.
A sewer perspective
Through its renewals program, Melbourne Water is working on a number of projects to rehabilitate sewerage infrastructure, using technologies such as slip lining and spiral wound/CIPP as a barrier to protect concrete assets.
“The methods used are conventional relining techniques to rehabilitate sewer structures. On large sewerage pipeline infrastructure, Melbourne Water has installed corrosion pins which allow for annual measurements on loss of concrete to be undertaken,” Mr Sulur said.
“Materials such as Glass Reinforced Plastic (GRP) pipes are currently used in sewerage related infrastructure to manage corrosion and new concrete structures other than pipes have a corrosion barrier such as High Density Poly Ethylene (HDPE) installed.
“IoT monitoring has also allowed for a quick deployment to monitor flow conditions when working in live environments.”
The utility is participating in a $3 million research project into smart lining for pipes funded by the Australian Government’s Cooperative Research Centre Projects stream, led by the Water Services Association of Australia (WSAA) and delivered in partnership with a team of manufacturers, applicators, utilities and research organisations.
“Melbourne Water is developing a bespoke condition monitoring tool to provide data that will assist decision-making around the impact of corrosion on assets,” Mr Sulur said.
While the project will be a huge leap forward in the development of smart technologies for the water industry, Mr Sulur believes that many corrosion risks can be effectively managed with the current rehabilitation and renewal methods available.
“The important factor is to identify the renewal or rehabilitation requirements before significant deterioration occurs. Early detection will provide a number of cost-effective solutions to manage the risk.”