Pipe bursting refers to the replacing underground pipes without digging a traditional construction trench. The scope of this east Brisbane pipe bursting project extended 266 metres, replacing 300mm cast iron water main pipe with 355mm PE. The job was divided into three runs of 96, 65 and 105 metres.
Challenges and preparation
In preparation, the existing mains pipe was inspected using CCTV to identify any potential problems and obstructions. Stop valves, hydrants and utilities running crossing or parallel to the mains were located to help determine where to safely excavate and install launch holes for the pipe bursting project.
One of the major challenges was the existing underground mains pipe ran closely beside concrete power transmission poles, with the potential risk of these poles cracking during the pipe expansion work. Being identified during the early planning stages meant problems were averted through collaboration with the energy provider on how to manage operations to prevent damage and public safety problems.
Another issue requiring thorough planning was traffic control. As a high-volume vehicle and pedestrian area, including local schools in close proximity, full-time traffic management was required. In this aspect, the benefit of trenchless pipe bursting is that a work site can be isolated to a 10 metre section, even when more than 100 metres of pipe is being replaced, as the majority of work is taking place underground.
The pipe burst’s location in a low-lying area, close to a creek and with a one-metre coverage of elastic moist clay prevented ground heavage during the bursting process and there was no damage to existing concrete footpaths.
In summary, the project started and was completed on time, with a four-day schedule. Working closely with the client, UEA Trenchless met all key project objectives, including:
– Installing as much pipe as possible with minimal restoration; a total of 266m with only 25 lineal metres of footpath requiring repair and only over the machine and launch pits.
– Minimal impact on vehicle and pedestrian traffic by using small, isolated work zones managed by traffic controllers.
– Retaining all 24 trees along the affected area with no environmental damage.