Problem:
The rising main located on Borlases Road, Port
Chalmers, had shown signs of advanced corrosion and
reduced structural integrity due to age-related
deterioration. The DN150 cast iron/AC pipe, originally
installed below ground level with shallow cover depths
(0.6–1.2m), was experiencing leak risks under pressure
(design operating: 1000kPa, max: 1600kPa).
Given the pipe’s location on a hillside with 30-40m of
elevation change and near sensitive marine and road
corridor environments, traditional open-trench
replacement methods posed challenges with traffic
management, excavation depth, reinstatement costs,
and environmental risk. A trenchless rehabilitation
method was required.
Solution:
The ASOE Fabric-Reinforced Flexible Plastic Pipe (FRFPP) is folded into a U-shape, winched through the main, and
expanded with air to form a close-fit, leak-resistant inner hose. It acts independently of the host pipe yet gains ring
stiffness from the casing—ideal where the pipe is mostly sound but excavation is impossible. This installation was
the first ASOE liner deployed in New Zealand, demonstrating its suitability for local pressure.