This growth will place significant demands on the city’s current pipeline water infrastructure, which is why it is planning ahead with the help of GEM Industrial and McElroy Manufacturing.
Originally built in the 1980s, the Gold Coast’s pipeline water infrastructure is already near capacity, with the expected population growth to cause more strain.
Considering such growth, the city has recently improved and expanded its water recycling network by constructing two of the longest marine pipeline crossings of their kind in all of Australia.
Long Term Recycled Water Release Plan
The first phase of the city’s Long Term Recycled Water Release Plan was not without its challenges.
A $70 million investment was made, which included upgrading pump stations and release points on the Gold Coast Seaway as well as construction of the two pipelines to handle the increased volume of excess wastewater that is treated, reclaimed and then pumped throughout the city to irrigate golf courses, parks and more.
To avoid disruption to the tourist destination and its pristine beach environment, the two new pipelines were installed beneath waterways and riverbeds using trenchless methods:
- A 2,500 mm diameter pipeline pulled under theBroadwaterCrossing between Quota Park and South Stradbroke Island using a tunnel boring machine.
- A 1,200 mm diameter, high-density polyethylene (HDPE) pipeline pulled under theNerangRiver bottom between Winchester Street and Waterways Drive with horizontal directional drilling (HDD).
For Victorian company GEM Industrial, which specialises in complex HDPE pipe projects, it was an exciting opportunity to be part of an infrastructure solution that will have a lasting and sustainable presence.
The company’s role was to fuse a new pipeline to handle the increased volume of excess recycled water that can be released at the Gold Coast Seaway with flow rates of up to 3,316 L/s.
“All our guys on the project were really proud to be there,” said GEM Industrial Owner Darren Chandler.
“It’s a beautiful part of the world and definitely a great project to be involved with for sure.”
The fusion
The Gold Coast coastline stretches 70 km, providing GEM’s pipe fusion crew with a gorgeous environment for fusing pipe.
The team fused 900 m of pipe at The Spit, the northern most part of the city that stretches into the seaway.
Since the area is a busy public beach, GEM fenced off a work staging area and adjusted that parameter daily as more and more Iplex 1,200 mm SDR 11 HDPE pipe was fused.
GEM had up to a dozen men working around the clock each day to ensure the beach could reopen as soon as possible; ironically, COVID-19 resulted in the beaches starting to empty towards the end of the project in April and May.
One of the more challenging aspects of the job was the pipe itself as it was up to 140 mm thick in places.
To ensure the integrity of the fusion joints, test pieces of the butt-fused joints were destructively tested by the ALS Brisbane Association of Testing Authorities (NATA) accredited lab for adherence to ISO 13953:2001 of polyethylene pipes and fittings with a 100 per cent pass rate.
“We write the recipe, we bake the cake and we then taste the cake,” said Mr Chandler about the testing process.
Simply put, GEM decides how the pipe is welded, the team welds the pipe and then they pull it apart to see how it performs.
MegaMc® 1600
GEM performed four to five welds a day for a total of 75 fusions using a McElroy MegaMc® 1600, a rugged fusion machine situated on a wheeled chassis for easy portability to the jobsite.
All MegaMc machines are equipped with a powerful hydraulic system to aid in the clamping and unclamping of the jaws, while hydraulic pipe lifts handle the pipe coming in and out of the machine.
The MegaMc 1600 was used in conjunction with a McElroy DataLogger® to record each step of the fusion process, letting operators know the correct temperatures, pressures and heating/cooling times are being followed during the fusion.
Mr Chandler said GEM data logs every joint on every job for peace of mind and comfort in knowing the correct procedures are always followed.
“The guys in the field can compare the joint to the log and know they got it right. If there is any doubt, we don’t have an issue with cutting a joint out,” he said.
“It’s definitely a good practice.”
The drill, the pullback and floating the pipe Before the pullback, GEM removed the internal and external fusion beads and then conduced hydrostatic pressure testing to ensure the pipeline was leak-free.
At the drill site, HDD contractor Dunstans used Sharewell reaming passes to ensure the borehole was big enough for the pipe.
To transport the pipe to the pull site, the buoyant pipe string was towed for 5 km escorted by barges and tugs along with the Gold Coast Water Police.
Once on shore and aligned in the direction of the borehole’s entrance, the pipe was connected to the drill head and into the hole for the pull.
Once positioned, the project was ready to pull back the 900 m preassembled pipeline under the river, light rail and bridge crossings.
Mr Chandler said GEM has had longer pulls of its pipelines before, but never a 1,200 mm pipe weighing approximately 300 t – resulting in a 30-hour process.
“It was really complicated and they did an excellent job,” he said, adding that GEM tends to take on projects that are a little more challenging rather than straight-line jobs.
“But if you get into stuff that’s a little unique, a little bit different, that needs a little bit more thought, a little more process involved – I think that’s our niche for the moment.”
Once the pull was complete, the HDPE flange connections were butt fused and the pipe was connected to the existing network – GEM’s preferred method, Mr Chandler explains.
The entire project was undertaken over a nine-month period including COVID-19 delays, but public disruption was minimal considering the scope of the project.
Now, the City of Gold Coast has a leg up on its future by serving more people through better infrastructure.
“We haven’t really stopped,” said Mr Chandler.
“It’s been quite positive other than logistics. Mobilisation across the country during COVID-19 has probably been the hardest, but there’s been plenty of work.”
For more information visit the McElroy website.