Scope of Works
Unity Water chose pipe bursting as the preferred method to replace the defective main for several reasons:
- Proximity to two schools and the need to reduce impact on local area
- The main was located under a footpath
- Proximity of the main to the root system of a large Moreton Bay fig tree
- Work was to be carried out close to main roads
- There was a possibility of working in contaminated or acid sulphate soils
- Project works were broken into 100 metre runs, with a pit located at either end for the machine and the other to launch the pipe into. Difficulties were apparent with the very first run, with minimal cover and the proximity to the local school.
- The potential to ‘heave’ the existing footpath during the bursting process (due to the minimal cover) was very high if the installation wasn’t managed correctly. UEA’s skilled staff limited this damage to less than 5% of the route, including the launch and receipt pits.
- Another issue identified during construction was the continual change in the existing pipe material. Sections of DICL were found at each of the road crossings, so specialised tooling was shipped from Germany to complete the bursting process.
Once the new pipe was installed, the connections were completed and the new main was pressure tested. A commissioning plan was then developed and completed in conjunction with Unity Water and their maintenance crew.