Trenchless Rehabilitation of a DN 900 Trunk Main Using a Multi-Liner Solution

Abstract

In 2019, Hunter Water detected a leak on a trunk water main that services a large proportion of the Lower Hunter Region in NSW. This water main is required to maintain security of supply to manage the peak demand over summer. The main is located adjacent to sensitive wetland areas and is directly underneath a critical arterial road. A traditional dig and renew methodology would require partial shutdown of this road, causing significant traffic disruption in an already congested area of Newcastle (Shortland). Hunter Water proceeded with a trenchless ‘triple line’ solution using Primus Line technology. The project, which involved a unique application of installing three flexible liners into the pipeline, was a first-of-its-kind for the Australian water industry. A similar project has previously only been implemented in Palmero, Italy. The triple line approach involved placing three DN450 Primus liners into the DN900 pipe, which were then fitted to a manifold made specifically for this application. This involved a reduction in open area only, resulting in a very small reduction in flow through this section. The final result was to line 140 metres of the including transition through two consecutive bends. The liners were installed successfully and the main returned to service without any road closures or disruption to the local community, and without the need to excavate or disturb any sensitive wetland areas. The paper describes the project progression and shows the make-up of the installed aramid liner as well as the functionality of the corresponding termination fittings.