The sunny, seaside village atmosphere of the Redland Bay Islands feels a long way from the hustle and bustle of Brisbane. Though as little as 2km from the greater Brisbane mainland, the islands’ pristine beaches, untouched bushland, and quiet coastal communities contrast strongly with the state capital. Drawn by the relaxed and secluded atmosphere, finely balanced between creature comforts and unspoiled nature, many holidaymakers have made the Redland Bay Islands their chosen getaway for generations, as have thousands of permanent island residents.
While accessing the islands to live or holiday has been easy, island life has come with some drawbacks. Communications and internet connectivity to the islands has been limited and unreliable at times, and whilst affording holidaymakers a good excuse to “switch off”, it was a different story for island locals and those more reliant on these utilities. As such, the communities of five of the Redland Bay Islands – Coochiemudlo, MacLeay, Russell, Lamb, and Karragarra – were keenly anticipating connection as part of the larger National Broadband Network project, scheduled for early 2020.
Major gains, major challenges
Awarded to telecommunication and ICT network provider Visionstream, the NBN Bay Islands project promised major gains – and a literal example of NBNCo’s purpose of “bridging the digital divide” – but not without complex challenges.
“This was one of the more complex builds that we have undertaken, but our team really enjoys the challenge of designing a process that meets the requirements of all stakeholders,” said Andrew Desmarchelier, Senior Project Manager Queensland (NBN) at Visionstream.
“Whenever we undertake a project like this, there is a lot of different factors to manage and at all times our focus is providing exceptional technical and service delivery for our client.”
Most significantly of all, the area’s unspoiled environment – including ecologically important seagrass meadows, and dugong, dolphin, and turtle populations – was subject to significant environmental protections by authorities, imposing a perfectly reasonable, but restrictive, additional factor on the project. The traditionally utilised method of completing island connections – marine trenching – was no longer suitable for this environment.
So the challenge was on for Visionstream to identify a commercially constructible method of connecting the islands, whilst complying with strict environmental and stakeholder requirements, and of course, managing cost, design life, and risk.
Investment in good design
In order to identify the best solution whilst balancing the competing priorities, Visionstream sought advice from the trenchless market. After exploring many different options, the organisation partnered with HDD contractors, Pipeline Drillers Group, and trenchless designers, Future-Proof Solutions, to design and construct the connections exclusively via HDD. The final design was settled on: 4 x 140mm HDPE crossings to the five islands, at lengths of 1000m, 820m, 550m and 350m.
Anthony Pendal, Project Manager at NBNCo, said the project was innovative not only in method, but in length. “The HDD to Coochiemudlo Island is the longest we’ve undertaken on the NBN rollout in Qld,” he said.
Future-Proof Solutions’ General Manager, Col Harris, said that some major engineering and construction constraints needed to be factored in. “As well as the obvious obstacle of the island geography, the project’s difficulty factor was magnified by the sand and rock geology, limited entry and exit points, and the logistical challenges of needing to use barges instead of land transport,” Col said. “But by investing in detailed and responsible design, including constructability studies and hydrofracture analysis, we were able to create a solution which fully complied with the strict project requirements and effectively mitigated the risks,” he said.
Expanding HDD applications and dispelling myths
Director of Pipeline Drillers Group, John Whitbread, said that the project demonstrated HDD as a competitive option in island connections. “There’s a misconception out there that long HDD bores under marine environments are too expensive, but cost comparisons in this project showed that wasn’t the case,” he said. “And to drill a pipeline in over a distance of a kilometre, causing no marine or surface disruption along the span, really sums up the win-win in terms of cost and benefit that HDD brings to NBN and other island connection projects,” John said.
Anthony Pendal from NBNCo agreed. “The expertise provided by all of our contractors has been an invaluable contribution and has really highlighted the advantages that HDD construction methods can bring to our local environments and communities,” he said.
HDD rig entry site on the NBN Redland Bay Islands project