Major wastewater projects instrumental to Rob Carr’s success

Rob Carr general manager Angelo Soumboulidis and project managers Thierry Candito and Paul Lee spoke to Trenchless Australasia about the ins and outs on two of Rob Carr’s major contracts. The company will also be exhibiting at this year’s No-Dig Down Under conference and exhibition, where it is the platinum sponsor of the event.

Breakfast Creek Sewer Upgrade

With Brisbane’s population expected to rise significantly over the next three decades, Urban Utilities, has invested $45 million to upgrade the wastewater network. The utility, which provides water and wastewater services to more than 1.6 million customers across its five service regions, is building a new trunk sewer pipe, known as the Breakfast Creek Trunk Sewer Main.

Stretching from Bowen Hills to Windsor, the pipe, which is 1 kilometre long and 1.8 metres wide, will be one of the largest in the utility’s 19,000km water and wastewater network, able to transport up to 400L of wastewater per second. Rob Carr General Manager Angelo Soumboulidis said the company was contracted for the project after working closely with Fulton Hogan Utilities on a design which leveraged innovation through an early contractor involvement process.

“We have a strong reputation as a leader and innovator in the industry with a proven track record of delivering high-quality work,” he said. “Working closely with our client, Fulton Hogan Utilities, our innovative final design solution minimised disruption to the surrounding community and limited environmental impact. “Our commitment to providing innovative solutions to our clients’ needs and our dedication to delivering exceptional customer service were also key factors in our selection for this project.” Rob Carr is using a 29t Herrenknecht microtunnel boring machine (MTBM) named Leila Perry.

In March, Rob Carr excavated and completed an underpinned segmental shaft up to 15m deep and lowered the MTBM into the launch shaft in Perry Park, on the corner of Folkstone St and Edmonstone Rd in Bowen Hills, beginning its journey towards Windsor. While this work was ongoing, the contractor also installed a 10t portal crane on the surface, which will provide logistical support for deliveries to site and lower jacking pipe to the foot of the shaft. The company is also concurrently constructing the receival shaft using a combination of techniques.

Since starting its journey towards Windsor back in March 2023, Leila Perry (the MTBM) has successfully traversed along Perry Park and under Abbotsford Road, six sets of live rail tracks either side of Abbotsford Road, and the Inner-City Bypass over the first 400m of the alignment. In addition, it has crossed multiple switching tracks within the Mayne Rail Yard switching centre over a further length of 350m over four storeys beneath the ground surface. The MTBM has since also entered the curved portion of its alignment with the MTBM ready to pass under Breakfast Creek some 840m into its 1000m journey. Soumboulidis said once past the creek, the MTBM will continue on the curved alignment and will traverse beneath the Airport Link Rd before arriving at its destination – a 7m internal diameter shaft at 10m deep. At the time of writing, the reception shaft was nearing completion and ready to receive the MTBM at the end of its journey before civil and mechanical construction works continue in the ensuing months.

“This will include works within both the reception and launch shafts to construct complex 3.6m and 6m internal diameter HDPE lined concrete maintenance holes inclusive of detailed benching, valves and gearbox drives, and a shorter connecting tunnel between the 6m diameter concrete maintenance hole and the existing S1 sewer to allow for connection of the new infrastructure to the existing wastewater system,” Soumboulidis said.

“A lot of preparation, ongoing planning and management by the site team has gone into maintaining the progression on this project, which will become our longest drive completed in Rob Carr’s history.” Once the MBTM completes its journey to Windsor, Rob Carr will undertake high density polyethylene welding of the pipe joints, while also carrying out the second stage of the S1 tunnel connection. Once this has been completed, Rob Carr will move onto constructing maintenance holes at either end of the pipeline alignment. Project Manager Thierry Candito said the experience and knowledge of Rob Carr in delivering complex projects helped them to meet three of the key challenging aspects of the installation, including the MTBM passing under a live rail crossing.

“We worked closely with our client Fulton Hogan Utilities and Queensland Rail to implement a 24/7 rail monitoring system,” he said. “We selected the optimum location to set up the theodolite that will continuously check target prisms installed along the rail. Through a cloud-based website, we were able to monitor the rails in real time while the MTBM operates underneath. Ultimately, we had no track movement for the entire duration of the tunnelling under these assets.” “As for the creek crossing, Rob Carr has worked with Fulton Hogan Utilities to meticulously plan and set all the required parameters and processes for successfully executing this important section of the alignment which will occur over the coming days. This includes additional tidal survey, geotechnical investigation and confinement pressure calculations.

Quinns Main Sewer Upgrade

Soumboulidis said the design and construction of the Quinns Main Sewer upgrade is now nearing completion after several construction and technical milestone having been successfully met. The new 1800mm internal diameter sewer allows for the conveyance of wastewater flows from wastewater pump stations in Ellenbrook, Jandabup and Neerabup into the Alkimos Wastewater Treatment Plant.

This significantly increases the systems wastewater capacity for meeting future demand in the northern districts of Perth. “The future success of the project was established early with several innovations incorporated during design,” Soumboulidis said. “We were able to increase the overall length of tunnelling for individual lines and in totality reduce our carbon dioxide emission footprint when compared to other pipeline construction techniques. “We were also able to significantly increase local industry participation using locally supplied reinforced concrete PVC lined jacking pipe also helping with the reduction of our footprint when compared to other pipe materials.” Paul Lee, Project Manager for Quinns, said the DN1800 concrete PVC lined sewer traverses a total length of 1931m with Rob Carr having completed the installation of 1400m via slurry pressure balanced microtunnelling using a Herrenknecht AVN1500, complete with an 1800 extension kit and VMT SLS guidance system. “The tunnelling portion of the works consisted of five tunnels in total, including one of the longest drives to ever be completed in WA crossing the Joondalup rail line and Mitchell Freeway, completed through sand and soft to hard pinnacle limestone,” Lee said.

The remaining 531m length of pipeline was constructed via open trench and pipelaying techniques. “We have completed in-situ and underpinned segment caisson shafts between 6m and 27m deep and six major concrete sewer maintenance structures,” Soumboulidis said. The works have been constructed through densely populated residential areas with the access chambers given priority to help minimise the impact to the general public. Lee said with all works now completed within the residential area, Rob Carr is focusing all its efforts on completing the two large vortex structures. “The second vortex in particular has been a major technical achievement given its depth and size 27m deep, and 8.4m in diameter.

The next phase of the vortex involves the installation of the large precast beam lifted in place mid-July 2023,” he said. The work will now enter the final phase with bypass pipework and the vortex tub installation. This intricate work involves a series of crane lifts which has required a significant amount of detailed planning to coordinate appropriately. Landscaping of the TAFE park is also nearing completion with planting in the final stages. The entire project is due to for completion in October 2023.

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