Repair of Damaged and Failed Sewer Liners, Blackall
Client: Blackall Shire Council
Project: Repair to damaged and defective sewer liners installed in sections of the sewer network
Blackall is a small remote community located approximately 950km north-west of Brisbane. Anything west of Blackall is considered “Beyond the Black Stump”. Blackall Shire Council contracted Downer PipeTech in 2006 to undertake the repair to damaged and defective sewer liners installed in 2000. Downer PipeTech operates a fleet of hydraulic pipeline robotic units, for the internal repair and sealing of defective pipelines. The units are fully self contained, and can operate in diameters of 135-800mm. In addition to robotic works, the vehicles are equipped to install Point-liners®, a localised lining product ideal for defect repair in lined and unlined pipes. The services available include:
- Cutting of intruding laterals
- Removing encrustation
- Preparation for lining
- Reopening laterals
- Epoxy sealing of junctions and pipe defects
- Installation of Point-liners® for junction and mainline repair
This project emerged after investigation by the Council found that the sewers lined with a fold and form PE product did not meet expected quality standards. The majority of the issues were related to installation issues and Council were not willing to accept the works as constructed. As part of our process evaluation, Downer PipeTech was required to demonstrate its ability to effect repairs consistent with Council expectations. A number of Sydney based fi eld trials on similarly defective lining product were conducted, along with evaluation of repair samples. Based on these trials, products proposed, and proven experience in similar works, Downer PipeTech was awarded the contract and commenced work on the project in November 2006.
Project Profile
Repair to Damaged and Defective Sewer Liners
This project involved the repair of damaged and defective sewer liners ranging from 150mm to 300mm diameter using a localised lining system known as Point-lining®.
Downer PipeTech was engaged to undertake the necessary repair work to restore the structural integrity of damaged pipes. The scope of works included:
- Pipe cleaning;
- Submission and approval of a repair plan to Council;
- Customer Liaison; and
- Final repair
The types of repairs that were undertaken included:
- Shrinkage of liner at manholes
- Tip holes and slashes in liner from cutting equipment
- Bulges
- Lateral connection cut-outs not suitable
The pipeline robotics unit was used to prepare the pipe for a full structural repair primarily through removal of various obstructions from pipelines (grinding/milling) and defects. This included recutting junctions, removing bulges and tree roots. Point-lining® is typically used for the repair of cracks, fragmentation, leakage, broken joints, capping off disused junctions, defective liner installations and corrosion. In this instance it proved to be the ideal repair solution. Polyethylene is typically extremely difficult to adhere to, but tests with the product showed that a very strong mechanical bond was possible, due to the resin characteristics exclusive to the Point-liner® product. Therefore the repair provides a mechanical bond to the existing liner effectively eliminating the potential for any leakage, as well as a complete structural bond to the host pipe where the resin comes in contact with it such as at liner ends, and junctions.
This structural local repair system does not suffer shrinkage issues, and has the ability to effectively seal the pipeline, eliminating future tree root and ground water ingress, which was evident in the system. An independent audit was conducted by a Council appointed consultant, which verifi ed that the Point-liner® repair methodology fully met all specifi ed technical and quality requirements. Approximately 200 Point-liners® were installed for this project, along with approximately 8 months continual robotic works.