Surfers Paradise Sand Backpass Pipeline the Gold Coast’s biggest infrastructure project, Stage One complete

The Gold Coast’s most expensive infrastructure build has presented a new challenge for engineers. SEE THE PHOTOS OF THE COMPLETED WORKS

THE $500 million recycled water pipeline to South Stradbroke Island is causing practical challenges with engineers dealing with cracked piping.

New councillors have been told a tunnel-boring machine had reached the exit shaft at the island, but there were problems with a section of piping 10-20m below the Broadwater.

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Map of the Gold Coast's long term recycled water network.

The Bulletin asked council a series of questions about the piping, but officers remain confident about the progress of the project, designed to help cope with massive population increases in the city’s north in the next two decades.

“The pipes that have cracked have been installed to form a tunnel or a sleeve between Quota Park and South Stradbroke Island,” a council spokesperson said.

“Our final carrier pipes for recycled water will be concrete encased inside the tunnel. Given that, it is not expected that cracking in the pipes which form the tunnel will have any impact on the final outcome of the project.”

The recycled water release system for the Gold Coast.

Officers admit the project is one of the most challenging and unique among major engineering assignments in Australia.

Key components are two marine crossings, two pump station upgrades, a pipeline on South Stradbroke Island and future plans for a “deep ocean release”.

“The combination of diameter, 2.5m externally, and length, 1380m of the tunnel, plus the mixed geotechnical conditions from sand to soft and hard rock qualifies this as a large and technically difficult pipe jacking project,” an officer said.

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“The pipe is also located under a waterway, therefore creating both environmental and site constraints in a highly populated area — adding to the project’s complexity.”

Council confirmed the northern works’ section, costed at $97 million and crossing the Broadwater, would be completed by September.

A pipeline being towed along the Broadwater and installed under the Nerang River as part of the City’s Long Term Recycled Water Release Plan. Picture: Jerad Williams

The Nerang pipe crossing and connection at the southern end was completed in June 2020, and the connection at the northern end in Waterways Drive, along with ancillary works connected to the roadworks project, were being completed before disestablishment in September 2020.

An exit shaft in O’Connell Park and pipework connection in Ocean Street started in June 2020, and tunnelling is to start in November from Quota Park towards O’Connell Park.

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A final pipeway connection on South Stradbroke Island is expected early next year.

The current system has been operating since 1984 and relies on second-treated water being pumped across the Broadwater from Labrador to an outfall at the western tip of the island on the northern side of the Seaway.

Aerial shot of the Gold Coast's long term recycled water plan.

A second underground pipe from the Nerang River through Main Beach connects to the southern side of the Seaway.

Both systems are limited because they only operate on the outgoing tides to control the nutrient load in the Broadwater.

Meanwhile, area councillor Darren Taylor remains “fully supportive” of a separate pipeline works on The Spit related to the sand bypassing project.

Work is underway to install a 7.8-kilometre pipeline to deliver natural sand from The Spit to protect iconic Surfers Paradise beach from coastal erosion.

Councillors are backing the funding, aware the city’s most visited beach is regularly impacted by storms and king tides, compromising foreshore infrastructure and affecting beachgoers.

Once completed, 6.3 kilometres of permanent pipe will run underground and connect to 1.5 kilometres of temporary above-ground pipe. This pipe will funnel sand from the existing Sand Bypass Jetty at The Spit onto the upper beach along Gold Coast northern beaches including Surfers Paradise.

Stage 1 has been completed. Photo: Supplied

Updated photos. Photo: Supplied

“The tender process is underway for Stage 2 construction works between Main Beach and The Spit,” Cr Taylor said.

“The City is working towards completion of the tender process by October and key construction dates negotiated with the contractor.

“I look forward to the entire project being completed by 2022.”