News | 30 May 2019
Upgrading a stormwater drain to protect properties in South Yarra from flooding has earned the City of Stonnington an award for engineering excellence.
Named the winner for Excellence in Public Works Project ($2m-$5m) at the recent Institute of Public Works Engineering Australasia awards, Council’s $2.1 million Melbourne High Drain Upgrade project has significantly reduced the threat of flooding to Claremont Street properties.
The project required the installation of a new 900mm diameter stormwater drain to replace the old 600mm pipe that was displaced and likely to fail. The old drain was operating well below capacity which was leading to localised flooding near the Melbourne High School entrance and the basement of a nearby building.
The new 900mm concrete drain was laid near the alignment of the old pipe extending some 250 metres from the northern end of Claremont Street under the Melbourne High School oval, under Yarra Street and Alexandra Avenue, to the Yarra River.
An important consideration of the project was to minimise disruption to residents, local businesses, the school community and users of the Yarra Main Trail. Using tunnel boring to install the drain meant, for the most part, works were carried out below ground leaving the oval, the streets and footpaths accessible at all times.
While the project was a huge success, it was not without its challenges. During the design phase the City was alerted to likely contaminated soil, which was confirmed by the Environmental Protection Authority (EPA). The EPA’s classification of the soil meant 725 tonnes of material was removed and replaced with clean fill.
Unexpected night works were also required when, during construction, there was concern the new pipe could hit a water main under Alexander Avenue. To ensure any conflict was avoided, over one night the road was opened, the water main exposed and measurements taken that confirmed there was sufficient clearance for the boring machine to pass – much to the relief of staff and contractors.
Successfully completed in June 2018, the Melbourne High drain upgrade is an example of how Stonnington’s commitment to careful design and clever construction continues to deliver important infrastructure improvements for the community.