Line type
Sewer rising main
Application area
Utility
Medium
Water
Region
Nelson
Country
New Zealand
Situation
In order to meet increases in capacity requirements and to provide alternative pipe routes with the goals of establishing pipeline redundancy, improved system resilience and future proofing in line with the overall network management strategy, the operator proposed to rehabilitate the pipe crossing under an estuary and to bring it back into service. The over 1,100-metre-long pipe had been abandoned since 2007.
The pipeline is laid in the Waimea inlet on New Zealand’s South Island, which is a large and shallow tidal lagoon that has high human use and high ecological values. It is a nursery area for marine and freshwater fish, has large shellfish beds, and is very important for birdlife.
Since there was no winch with a sufficient cable length available, a trailer winch equipped with 1,000 metres of cable and another 200-metre extension was used.
The presence of bends and the sheer length of the pipeline ruled out sliplining with HDPE and also reduced close-fit HDPE.
Technical details
Material of host pipe
Asbestos cement, class B
Diameter of host pipe
DN 525
Transported fluid
Residential wastewater
Operating pressure
6 bar
Total length
1,100 m
Number of sections
1 section
Number of bends
Several
