Brisbane City Council, working with Brisbane Water and a team of specialist construction and design companies led by Leighton Contractors is delivering the $A13 million Australian TradeCoast (ATC) sewer project which will include 12.5 km of new pipeline, three new pump stations, and upgrades to four existing pump stations.
This significant investment in critical wastewater infrastructure will increase the TradeCoast precinct’s attraction for commercial and industrial tenants as a rapidly growing regional trade hub, and enhance the wastewater network’s performance for local residents.
The Australia TradeCoast precinct is already home to over 7,600 businesses and is achieving the highest business expansion growth rates in Australia. It is expected to contribute $A4.9 billion and 51,000 jobs to the Southeast Queensland economy by 2010.
Project Delivery - Brisbane River crossing
The Brisbane River crossing installation was always going to be a difficult and trying project. Critical to the overall success of the Australia TradeCoast Sewer Project; Stage Two construction involved a crossing of the Brisbane River using Horizontal Directional Drilling technology. The drilling and pipeline installation was part of a challenging and highly complex project. The project team developed and implemented a detailed engineering design and execution methodology to minimise potential drilling and pipeline installation risks.
The geology to be encountered for the project indicated that the subsurface lithology to the depth of the investigation was relatively consistent, comprising Quaternary age alluvial deposits overlying weathered rock associated with the Tertiary age Petrie Formation. Each of the six boreholes
intersected the interface between these two geological units within a narrow level range between RL –34.4 m AHD and RL –39.6 m AHD over a distance of approximately
600 m. The overlying gravels presented the
challenge to ensure all drilling activities and pipeline installation operations could be carried out continuously providing a successful installation. Casings were used to allow drilling to proceed within the gravels until bedrock was encountered as planned.
The crossing was drilled from a site on the north side of the Brisbane River at Yarra Street using a 9 7/8 inch TCI Drill Bit driven by a Wenzel 6 3/4 inch Mud Motor. A Tensor Steering Tool using Trutracking provided magnetic guidance for the 762 m River Crossing, which included a compound curve with a 26 degree alignment change.
The product pipeline was a DN 400 HDPE 100 PN 20 pipe prepared, welded and tested by Leightons on the north side of the Brisbane River. Once all pilot hole, hole opening and hole conditioning had been completed, the CoeDrill 550 Rig Spread was mobilised to the south side of the River at Lytton for the pipeline installation operation. This allowed the pipeline to be pulled through the longer open section of gravels before entering the basalt bedrock and back up through a shorter section of gravel on the south side.
Work commenced on site in mid-June 2004 working on a 24 hour a day basis. The pipeline installation operation was completed in early August. The ultimate success of the Brisbane River Crossing reinforces Coe Drilling’s position as a leading Australian supplier of HDD crossings.
