Late on a Friday afternoon in June 2020, council’s Civil Maintenance and Construction teams suddenly realised the surface of Galloway Road in O’Sullivan Beach, which crosses Christie Creek, was at risk of partial collapse.
CCTV revealed all four corrugated iron pipes (or culverts, which allow water to flow under the road) had significantly deteriorated, and with rain forecast for the following evening, time was of the essence.
“Keeping water out of the collapse site was critical,” says Iestyn Broomfield, City of Onkaparinga Construction Project Officer.
“Culverts provide drainage to support the wellbeing of the surrounding environment, preventing erosion and allowing aquatic wildlife to move freely through the waterway.
“It can be enormously costly, damaging to the environment and very inconvenient to road users when they collapse.”
With more than 5000 vehicles using Galloway Road—which provides the only access across Christie Creek for O’Sullivan Beach—each day, council staff knew they had to find an effective solution fast.
“We moved quickly to collaborate with teams across the organisation, using road plates [a temporary road covering] as an interim measure and monitoring the site around the clock to identify any deterioration to the embankment supporting the road,” Iestyn says.
Council engaged leading water infrastructure company Interflow to develop a longer-term solution using technical analysis, engineering and survey.
Interflow and council used a Rotaloc—a high-tech machine that winds a PVC liner inside damaged pipes to repair their structure—but a key concern was the safety of crew members who would normally be required to enter the pipes to use it.
Instead, they modified the Rotaloc’s hydraulics so they could operate it remotely, allowing it to perform the first non-man-entry use of the machinery in the state.
Iestyn says the process is expected to have secured the culverts for the next 50 years.
“It’s amazing what you can achieve when you combine teamwork with out-of-the-box thinking and innovative technology,” he says.