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Challenging conditions no match for PE100 HSCR on debut

Australia’s first Iplex Millennium® PE100 HSCR pipe, manufactured using Qenos’ HCR193B® resin, has been installed by Maxibor using HDD in Yeppoon, QLD.

The installation will meet the future water needs of the growing ocean side community. The tough ground conditions dictated the use of the specially-developed resin to ensure the pipeline had a design lifetime of more than 80 years.

Yeppoon in central Queensland is the principal town of the Livingstone Shire Council on the Capricorn Coast and is renowned for its beaches, tropical climate and the Keppel islands out on the bay. In 2017, to meet the region’s growth in population, the council was looking to expand its potable water distribution infrastructure with the installation of a new pipeline.

The pipe string being welded.

Following a competitive tendering process, Livingstone Shire Council Urban and Water Construction Coordinator Marco Bandiera says opting for a new high-density polyethylene (HDPE) pipeline installed by horizontal directional drilling (HDD) was a logical choice.

“In the current configuration, two ductile iron potable water pipelines are contained within the bridge structure over the Causeway Lake crossing,” says Mr Bandiera.

“The bridge requires maintenance and the location of the existing water mains prohibits access to effect the repairs and routine maintenance. The council opted for new pipelines under the lake to ensure reliable potable water supply to the communities south of the lake.

“This project will also provide an increase in flow capacity allowing for future population growth.”

Pipe partnership

The critical importance of the pipeline, combined with the HDD installation and difficult ground conditions – which included large amounts of rock – resulted in Livingstone Shire Council selecting polyethylene (PE) pipes made from Qenos’ Alkadyne HCR193B resin. The pipes, manufactured by Iplex Pipelines, are Australia’s first made from PE100 resin classified as high stress crack resistant (HSCR).

Iplex had already engaged with Livingstone Shire Council and was in the early stages of the project when the pipe manufacturer proposed an alternative design based on the use of the Millennium PE100 HSCR, which is manufactured using HCR193B. The alternative pipeline design was eventually selected in favour of standard PE100 pipes in May 2017.

“For a long-term investment into our Shire’s infrastructure, we wanted a solution with the longest possible lifetime,” says Mr Bandiera.

“The Millennium pipe design, using PE100 HSCR, provides a design lifetime of at least 80 years for this particular project. No other PE pipe could match this.”

Scratch proof

The pipe material ensures scratches on the pipe that occur during trenchless installation will not develop into cracks, extending the service life of the pipeline and reducing maintenance costs.

Alkadyne HCR193B’s stress crack resistance performance is checked at every production run and the material successfully meets all requirements set out in the Plastics Industry Pipe Association of Australia’s  POP016 guideline for the use of PE100 HSCR. Millennium pipes have also been appraised and approved by the Water Services Association of Australia.

The Iplex Millennium DN 450 and DN 315 pipes, manufactured using Qenos’ Alkadyne HCR193B resin.

The PE pipe manufacturing process relies on finely optimised machinery settings specific to each resin used. Iplex Pipelines National Process Technician PE Peter Cameron reported the successful manufacture of twenty 20 m lengths of DN315 and DN450 PN20 Millennium pipes using Alkadyne HCR193B for the first time.

Mr Cameron says virtually no off-spec was created during the process, adding that the Qenos resin allowed for the tight control of dimensional tolerances, as well as providing a very smooth surface finish. Blue stripes, made out of Qenos’ PE100 HSCR base resin, were also included in the design, as scratches that may lead to slow crack growth generally occur on the outer surface of the pipe.

The pipes were manufactured at Iplex Pipelines’ plant in Toowoomba, 125 km west of Brisbane and delivered to the project site in June of last year.

Anything but routine

The installation, designed by Jason Gustafson from Livingstone Shire Council, comprised two pilot holes 380 m in length, drilled to a maximum depth of 17 m. The holes were subsequently enlarged using a reamer to allow for the pull-through of the DN 315 and DN 450 pipes.

An HDD rig in operation on site.

HDD contractor Maxibor Australia was selected for the installation. Maxibor Business Development Manager David Turner says the project was no routine installation.

“The ground conditions made it a challenging job. The first 260 m of the installation was rock and the last 100 m was other than rock (OTR),” he says.

“So, we had to actually drill a pilot hole of about 258 m and then forward ream the hole out to the required size. Once the rock section was completed, we pushed out to drill all the way through and then reamed the OTR section.”

Pipeline assembly

Two 400 m long pipe strings were assembled on the southern shore of the Causeway Lake by butt welding the 20 m sections of pipe. Although Alkadyne HCR193B is a new class of PE100, standard welding parameters can be used.

Weld integrity was verified using the bend back test and all beads were retained by Livingstone Shire Council for quality assurance.

The pipes were then pulled through the bore hole back to the drill rig on the northern shore of the lake. The drag and tensile forces on the pipe were minimised by filling the submerged part of the pipeline with water during the pull-through to counteract buoyancy.

The trenchless installation was completed by attaching flange adapters to connect to the distribution network. The adapters were connected by electrofusion welding using standard fittings, demonstrating HCR193B’s excellent welding compatibility with conventional PE100 resins.

Project completed

The installation was completed by the start of September 2017, with the project delivered on time and on budget. The short turnaround from the awarding of the tender to completion minimised the disturbance to the community.

All stakeholders involved in the project were highly satisfied with the outcome. For Livingstone Shire Council, Millennium PE100 HSCR provided the only viable long-term solution to rehabilitate this water main section by HDD.

Mr Turner says Maxibor is looking forward to working with the pipe again, and testing the limits of the technology.

“It’s the first time Millennium pipe, based on Alkadyne HCR193B, has been used in Australia and we’re glad to be associated with that milestone,” says Mr Turner.

The Yeppoon installation has highlighted how PE100 HSCR ensures the structural and operation integrity of a pipeline, even under the most challenging installation and application conditions.

This article was featured in the March edition of Trenchless Australasia. To view the magazine on your PC, Mac, tablet, or mobile device, click here.

For more information visit the Qenos website.

If you have a project you would like featured in Trenchless Australasia contact Journalist Chloe Jenkins at cjenkins@gs-press.com.au

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