Iplex’s innovative product Restrain has contributed to the success of the Townsville Wulguru Gravity Sewer Upgrade.
Restrain is a PVC-U pipe designed for both new sewer networks and for replacing existing underground gravity sewer infrastructure. The pipe sections have a threaded socket and spigot joint. The rubber ring seal for the joins is nested in a groove behind the spigot thread, which ensures that it is not dislodged during installation.
Restrain Sewer Pipe’s compatibility with trenchless technologies means that it was the perfect choice for use on the Wulguru Gravity Sewer Upgrade. Managing Director of Edge Underground, Stuart Harrison, was the installing contractor on the project. Harrison says that the biggest thing saved by using Restrain was time.
The new technology gave Harrison’s team the opportunity to run a keyhole operation. Instead of the trench that would have been required by traditional welded or glued pipe, the shorter lengths could be lowered into a smaller trench, each one only 4×2 m, and either pulled or pushed through a pre-bored hole to another trench at the other side. Running out of a small footprint like this means that contractors also save time by minimising the reinstating of trenches after laying long lengths of welded or glued pipe.
Edge Underground also saved space with shipping, because the sections of the pipe can be delivered on a pallet rather than longer lengths being delivered by truck like welded products.
Taking only a couple of minutes to connect the sections, where in comparison solvent weld joint pipes could take up to 24 hours to dry.
“It takes as long to get the pipe off our drill-rod at the other end, as it does for the pipes to be screwed [together],” says Harrison.
André Nunn, Technical Sales Engineer for Iplex Australia, says that the advantages of Restrain are not just in saving time. The pipe length is custom designed to fit the width of the insertion pit or maintenance structure, meaning a lot less above ground space is required by the contractor and less excavation leads to less disruption and cost savings.
In addition, PVC-U has a ring bending stiffness of more than three times other poly options, meaning the wall thickness is three times thinner which leads to large cost savings by having a smaller bore hole for the same hydraulic capacity.
The product is also quite stiff, again making it ideal for the Wulguru Gravity Sewer Upgrade.
“The pipe stiffness is a minimum of SN16… for typical sewers the minimum rating is often SN6 to SN8,” says Nunn. “The stiffness class, SN16, makes the product suitable for use in deeper installations. The threaded joins also provide full axial restraint, allowing for pushing and/or pulling through pre-bored holes.”
“Contractors have always wanted to go with the cheaper option of PVC pipes”, says Harrison. “The problem is that PVC pipe has always been designed for laying in a trench. Pushing traditional pipe into a bore hole creates increasing friction as the pipe is pushed deeper, creating pressure on a product that isn’t designed to be pushed on.
“Eventually it’s easier for the pipe section to slip into each other than to push further into the bore hole. The full axial restraint of Restrain makes it the perfect pipe to use with micro-tunnelling machines and other trenchless technologies.”
Townsville will also benefit from the use of Restrain in the future. The pipe is compatible with more traditional PVC fittings, so if work needs to be done in the future, traditional fittings can also be used.
Product Manager Andrew Omer-Cooper says that Restrain has the added benefit of being an Australian made product, ensuring a strong local supply chain. This gives Iplex the flexibility to meet customer project need quickly and effectively. The initial project was drafted for 300 mm pipes when Harrison was contracted, but the change to 375 mm was met with a minimum of fuss.
“The product is also made using Best Environmental Practice PVC and is a Green Building Council Australia certified product, that is very important to Iplex,” he says.
Installation options for Restrain sewer pipe include pipe reaming or pipe eating, auger boring or guided boring, horizontal directional drilling, as well as the micro-tunnelling installations undertaken by Edge Underground for the Wulguru Gravity Sewer upgrade.
Harrison says Townsville City Council deserves credit for the decision.
“The industry is forever evolving, but we need the people around the industry to evolve with us,” he says. “What is needed is more people investing in these newer technologies.”
The Wulguru Gravity Sewer upgrade has been undertaken to address some of the suburbs sewer capacity issues, and are the third stage of the Council’s $54 million Southern Suburbs Rising Main project.
This will see more than 13 km of pipeline laid due to the existing system being unable to cope with the increased capacity for the Wulguru community.
For more information visit Iplex’s website.
This article appeared in the August edition of Trenchless Australasia