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Saltire were engaged by Rob Carr Pty Ltd to assist in providing bypass set ups to an existing water main requiring replacement as part of the Denny Avenue Level Crossing Removal works, which forms part of the overall MetroNet program. The existing water main provided supply to significant commercial properties and required to be maintained during the works.

Saltire Infrastructure utilised 3 technologies to assist in this requirement, namely Hot-Tapping, Line Stopping and the Hawle System 2000 HDPE mechanical coupling.

To maintain this supply, an overground DN180 HDPE by-pass pipeline was installed along the property boundaries and installed underneath driveway accesses. This by-pass was installed using the Hawle System 2000 mechanical couplings in lieu of traditional welding methods, due to time constraints and availability of panel approved welding contractors.

Upon successful pressure test of the new by-pass main, the existing main was hot-tapped through a valve and connected to the new by-pass. With both mains live in parallel, all service feeds were transferred to the new by-pass main. With all services transferred, the existing main could now be decommissioned, which is where Saltire utilised the line-stopping equipment to facilitate cutting and capping of the existing mains, making the pipeline redundant and safe to replace.


The by-pass was installed and commissioned in just one day, and all services along the affected area were successfully connected. The quick and efficient installation of the by-pass ensured that it was possible to line-stop without isolating the mains, which provided continuous water supply to the commercial businesses not only during the bypass installation process, but also for the duration of the main works program.


This case study demonstrates the successful integration of 3 technologies within the Saltire business to provide an overall project solution to the benefit of clients and stakeholders. The installation of a by-pass pipeline with mechanical couplings on potable water supply is the first of its kind for Perth W.A. providing this innovation significantly enhanced the overall works program on a time critical project.