Council has completed an upgrade of the main sewer in Augustine Street. The project began in mid-August 2025 and was completed by the end of December.
Disruption to traffic was minimalised because, instead of an open trench, contractor Hadlee & Brunton was able to use a pipe-bursting method using manhole access points. This is a trenchless sewer replacement technique that uses a specialised bursting head to break apart the existing pipe while pulling a new pipe into place behind it.
The existing earthenware pipe has been replaced by a restrained PVC pipe designed specifically so that joints do not pull apart under pressure. Unlike the original earthenware pipe which degrades over time, upgrading with restrained PVC provides a more robust, long-lasting network which can withstand natural disasters such as earthquakes.
Approximately 350 metres of pipe was replaced using the trenchless method. Originally one section was going to be open trenched but favourable ground conditions gave the contractor confidence to pipe burst the entire length.
Another trenchless technology, fibreglass lining, was used for the laterals which connect dwellings to the main. This method, necessary due to the depth of the pipes and the risk to property, inserts a lining made of fibreglass to rehabilitate and reinforce the existing pipe. This also protects the pipe from tree root intrusion which is one of the primary reasons for blockages in older networks.
Newly dug trenches can lead to areas of settlement which need future repairs, so the trenchless methods present a cost-effective solution.
Council is hoping that future renewals can be undertaken using the same methods.
