A program using smart technologies to improve drainage management in the City of Gosnells, in Perth’s south-east, has been recognised on the national stage.
The City’s Smart Drainage program won the Disaster Readiness and Recovery Category at the recent National Awards for Local Government.
Mayor Terresa Lynes attended the awards ceremony at the Australian Council of Local Government Gala Dinner in Canberra, where she accepted the City’s award from Prime Minister Anthony Albanese.
“I feel proud to see a team from the City of Gosnells recognised on a national level for the innovative and effective work they are doing in our local community,” Mayor Lynes said.
“It is also rewarding for the Council to see the City’s team acknowledged for their work on a program that has had a positive impact on residents and businesses within the City of Gosnells.”
The program was also recognised at the Institute of Public Works Engineering Australia (IPWEA) WA Awards in March, for Excellence in Asset Management and Excellence in Innovation – Metropolitan and won the Excellence in Asset Management Award from Stormwater WA.
The technologies implemented as part of the program include tractor-mounted CCTV to investigate inside pipes. There is also the ability to push cameras beyond the reach of the tractor.
Other features include Ground Penetrating Radar to identify and accurately size voids in the soil surrounding damaged pipes, expanding foam technology to fill those voids and flow meters linked to texting software so the City’s drainage crews are called to the site when water flows are high and before flooding occurs.
The Smart Drainage program began in 2022, following a thorough analysis of drainage, which identified a high incidence of sinkholes and tree root intrusion, particularly in areas where pipes with an ‘open joint’ (without a rubber ring seal) had been previously installed.
These open-jointed pipes were used extensively in subdivisions in the City between 1980 and 2009.
Inspection and repairs
Traditionally, the City would have outsourced drainage inspection to contractors. However, investing in a new tractor-mounted CCTV system and bringing this task in-house has already saved the City approximately $125,000, which is expected to be an annual saving.
The new CCTV system is operated by a single person and there is no longer a need for a person to physically enter pits. The new system also provides more accurate data about the condition of, and grade changes within, the drainage network, and is powered by solar power and batteries.
The proactive CCTV inspections of the drainage network revealed that regular pipe education and cleaning using chain flailing or jetting, which was required to clear roots and other buildup from the drainage network, had caused damage to the drainage network over time.
The excavation and repair of damaged pipes was also previously outsourced to contractors, which was both expensive and disruptive to surrounding residents and businesses.
In response, the City sought to bring this critical task in-house as well. Further, a new product to reline damaged pipes, which could be installed in-house and could withstand jetting and flailing, was successfully trialled and is now being employed where required across the drainage network.
Sink hole prevention
While the City could now accurately inspect inside the drainage network and effectively repair sections of damaged pipe, it was critical to also consider problems occurring outside drainage pipes.
Traditional sinkhole identification and rectification methods employed by the City were labour-intensive, with the process requiring probing to locate the sinkholes, then excavation, repair and filling. This process incurred significant costs and caused disruption to the community.
Consequently, the City collaborated with a contractor to conduct field trials of ‘Stream DP’ deep ground penetrating radar technology. This has enabled the City to identify underground voids more efficiently and with less disruption than with the traditional process.
The City continues to engage contractors for this task, although consideration is turning to the purchase of Ground Penetrating Radar equipment and bringing this role in-house as well.
Armed with the capability to identify and accurately size voids, the City began to research better methods to rectify the voids.
Injection of foam grout or resin emerged as the best treatment option for the City. This involves filling the void and encasing the pipe joint to effectively prevent further sinkhole formation, without the need for extensive and disruptive excavation.
A test site in Thornlie allowed a void to be filled with the removal of only a few paving bricks, instead of the excavation of an entire section of footpath and road.
A tale of two rivers, one City
Perth is renowned for being dry, but with two major rivers, the Canning and Southern rivers, plus extensive wetland areas within the City of Gosnells boundaries, flooding was a significant focus for the City.
“Most community members don’t often think about drainage, except when floods occur,” Mayor Lynes said.
“While much of the City’s Smart Drainage program involves proactive work to prevent floods, the City needed to improve the way it identified and responded to flooding events as water levels begin to rise.”
To improve the City’s flooding emergency response, priority sections of the drainage network were identified and new digital rain gauge and flood sensors were installed in those areas. The City then trialled ways to program the technology so flood alerts could be delivered to drainage maintenance crews and after-hours call-out teams by text message.
The method proved to be a highly successful and efficient way to respond to maintenance needs during storm events and will be progressively rolled out to more sites in the City in the coming years.
Another simple, cost-effective change has also been implemented to help prevent blockages downstream and proactively address a specific cause of flooding. This involves the use of PVC traps designed by City staff. These are strategically placed in pits in flood-prone locations to capture leaves and mulch before they enter the drainage network, minimising the impact of debris on the drainage system.
Team approach
Bringing several tasks which were previously outsourced to contractors in-house and adding new technologies meant significant changes to the way the City’s Drainage Maintenance staff operated.
The success of the program was in part due to effective communication about each project, and collaborating with staff to encourage valuable input from team members in the decision-making process.
Additional training and workshops were provided in the use of the new software, safety protocols and installation methods, which offered opportunities to bring team members together and cultivate a positive work culture.
Future flow
As a rapidly growing outer-metropolitan local government area spanning more than 127 square kilometres, the Smart Drainage program has provided a greater level of certainty for urban planning and significantly reduced flooding issues.
“By modernising the City’s drainage operations, the City has successfully improved response times and resource allocation, enhanced productivity and provided a safer, less disruptive environment for residents and staff,” Mayor Lynes said.
“It has taken considerable research, experimentation and innovation, however the City is extremely pleased with the outcomes.”
