Building Resilience in Our Wastewater Networks by Recommissioning Unused Assets

Abstract

Under the suburb of Marrickville in Sydney’s Inner West runs three sewer rising mains. The Central and Northern mains had been taken offline due to previous failures. The Southern main remained the only operational pipeline and was itself showing signs of deterioration. Sydney Water wanted to bring the decommissioned mains back online to ensure the network had sufficient contingency should the unexpected happen. Interflow was engaged by Sydney Water to rehabilitate both the Central and Northern rising mains. Both existing rising mains were DN600 pipelines made from a mixture of both cast iron and concrete pipe. The rising mains also had both vertical and horizontal bends along the alignment. Increased development in the area, combined with proximity to underground services and train tracks, meant that access to the alignment was very limited. Interflow needed to find a solution that could be installed over longer distances between and around bends. The solution was to install Primus Line from the sewer pumping station to discharge points near Illawarra Road. Due to the inactivity of the existing pipelines, extensive cleaning and rehabilitation was needed. The works added a minimum 50-year service life to both the Central and Northern sewer rising mains, improved the system’s resilience, and will allow Sydney Water to carry out future inspection and repair on the Southern main. It also demonstrates that there are viable options available for complex pressure pipelines in high-density residential areas. 1 No-Dig Down Under 2023 Building resilience in our wastewater networks by recommissioning unused assets Paul Everett, Danny Tang, and Jerry Sunarho