For this job in an industrial area to the east of Brisbane an existing 300mm cast iron water main was replaced with 355 mm PE for approx. 266 metres. This was completed in three stages of 96, 65 and 105 m each.
The job was completed in four days which met all objectives to schedule, including creating minimal traffic disruption and making no environmental impact on established trees along the mains route.
Above: Expander head is attached to pre-welded PE pipe
Above: Expanding head is pulled into machine pit
Above: Blade enters machine pit by smashing the existing Cast Iron main
Above: Blade and expander entering existing cast iron main
CCTV was used to inspect the original main for potential obstructions, such as stop valves, hydrants and defective sections of the existing main. All obstructions and utilities, crossing or running parallel to the existing pipe were identified and exposed.
The existing main ran hard up against large transmission power poles and there was the risk that during the bursting operation, these concrete poles could crack during the expansion process. This problem was identified during the pre-start up consultation which meant that contact with the energy provider was possible and an appropriate plan was put in place to protect these poles.
Above: During process, machine is braced sideways and pulls against a steel plate
High vehicle and pedestrian traffic, including nearby schools, called for full-time traffic control with additional controllers necessary to maintain public safety and escort pedestrians past the work site. The benefit of pipe bursting is that the work site can be isolated to within a 10 m section even though 120 m of pipe is being replaced as the majority of replacement is happening underground.
Above: New PE pipe is inspected as it passes each inspection hole to ensure no damage
Above: New PE pipe is pulled into place during the bursting process
UEA Trenchless started and completed the project on time and all key objectives were achieved:
- To install 266 m of new pipe with minimal surrounding restoration required. 25 lineal metres of footpath needed repair, which was limited to where the machine and launch pits were located.
- There was minimal impact on vehicle and pedestrian traffic because the job was isolated into small work zones.
- None of the 24 trees along the route of the mains were removed or damaged during operations.