The program is the next big step in preventing exfiltration and infiltration from and into the sewage system.
Over the last ten years, Singapore has completed Phase 1 and Phase 2 of its sewer rehabilitation program in more than 700 km of public sewers. PUB has now decided, in its Phase 3 program, to focus on the Marina Catchment, to improve the quality of the future Marina Reservoir. The Marina Reservoir is set to become an integrated watersports hub and premier tourist attraction and will add to the local water supply and increase the water catchment from half to two-thirds of Singapore.
After introducing RibLoc’s Ribsteel™ spirally wound technology for large diameter sewer rehabilitation in 2002 for the Phase 2 program, Chevalier Pipe Technologies (CPT) began smaller diameter rehabilitation in December 2006 with the Expanda technology for the Phase 3 program.
The Expanda technology is a spirally wound liner for diameters ranging from 150 to 750 mm. The system is a close fit liner in direct contact with the host pipe. The system consists of a single strip of PVC profile, which is spirally wound into the existing pipeline by a patented winding machine positioned at one end of the pipeline. Once installed, the liner is then mechanically expanded to get in close contact to the wall of the host pipe.
Article continues below…CPT’s local partner in Singapore, Johnson Pacific, chose the Expanda system for this project.
The Expanda process covers the whole diameter range from 150 to 750 mm with only five different PVC profiles. Due to the expansion process inside the existing pipeline the material does not require any pre-manufacturing to exact size and so cuts down project lead-time.
One other advantage of the spiral wound liner system is the quick mobilisation and installation period. All projects in the Phase 3 rehabilitation program include a high percentage of private drainlines, which are mostly small in diameter (150 mm) and very short in length — up to a maximum length of 10 m only. The installation period for spiral wound liners is linked to the length of the pipe, which ensures that the disturbance to private properties is limited to a bare minimum — in some cases only taking one hour.
The purpose of Phase 3 is to stop all exfiltration of wastewater from private drainlines and PUB’s public sewer lines. The canals and rivers that lead to the Marina Bay Reservoir are identified and those premises with drainlines or sewers within the vicinity of those canals and rivers are subject to rehabilitation. There are twelve sub-catchments within the Marina Catchment and each comprises approximately of 30 km of drainlines and public sewers.
