Glass-reinforced polymer can save time, effort and cost in even some of the most exacting subterranean installations, as a recent under-rail project proved.
Sometimes it’s easier to go with the traditional way of doing things in engineering, particularly when an important stakeholder supports that strategy.
But sometimes it’s worth convincing all stakeholders of a more innovative method, especially when the benefits are overwhelming.
That’s what Mohamed Yoosuf, Senior Standards Engineer at Greater Western Water, realised during a recent trunk sewer (Rothwell Branch Sewer – North of RRL) installation under a Regional Railway line in Truganina VIC 3029.
“This project became tricky for us,” Yoosuf says of the installation that needed to connect two suburbs. “Normally we can choose the most suitable jacking pipe, but this project also had a rail authority as a stakeholder.”
“They requested that GWW lay a reinforced concrete (RCP Class IV) casing pipe, which is a protective sleeve for the sewer pipe. The casing is to take care of the railway load through which the carrier pipe (open-trench GRP) has to be laid.”
A further challenge was to cross underneath an existing water main and achieve minimum vertical clearance. The sleeve and carrier solution would not be able to achieve this without increasing the sewer depth which was not possible either.
Yoosuf strongly believed a glass-reinforced polymer (GRP) jacking pipe would offer a better solution for this project.
It would be capable of coping with the railway load, would provide a more accurate slope for the gravity sewer line, and would boast several other performance benefits.
Benefits of Flowtite GRP pipes
Flowtite is a composite pipe made of various materials that offer unique properties, says Don Tasevski, Senior Sales Engineer for Iplex.
“It’s a flexible pipe that can be used for water, for sewage, for jacking pipes, and for a whole range of engineered applications,” he says.
“A jacking pipe is bored through the ground rather than laid in an open trench,” he explains. “This means much less excavation, saving time, effort and cost, and making things far easier when you’re going under a road or railway.”
Tasevski provided technical support to Greater Western Water on the project, providing data on structural loads, the ability of the pipe to be pushed through the ground, the potential size of the pipe, and other factors.
But, he adds, “It was really all about satisfying the rail authority that this pipe was going to be suitable for that application.”
“We went through the Australian Standards in terms of how strong the pipe needed to be. We demonstrated the differences between concrete and GRP, and showed GRP can have up to two times the compressive strength of concrete in terms of its jacking ability.”
The Flowtite pipe was also more flexible, meaning less chance of structural failure during the installation. And in this rail crossing project the Flowtite GRP jacking pipe acted as a sleeve coping with rail load and acted as a carrier conveying the sewage.
“And in terms of sewer environments, GRP is resistant to sewage gases such as hydrogen sulphide,” Tasevski says. “In fact, Water Services Association of Australia has completed appraisals on the Flowtite brand GRP pipes (both open-trench to AS 3571 Part 1 & 2 and jacking to ISO 25780) and given it a Class A, or 100-year, life expectancy.
Customer service matters
The amount of information and assistance provided by Iplex to the rail authority, Yoosuf says, was a major factor behind Greater Western Water’s confidence in using the Flowtite product.
“The consultation process took six months,” says Yoosuf, who has led major water projects around the globe, including in Sri Lanka, and Qatar.
“Eventually we were able to convince the stakeholder about laying a jacking pipe that would act both as a casing and carrier. Iplex helped us to do all of the computations around vertical load and horizontal load and to ensure the product med Australian Standards.”
“The quality of the product was a highlight, it was the reason we believed so strongly in it. But the quality of the customer service was also excellent.”
Find out more about Flowtite GRP Pipes.
