A complicated project by Yarra Valley Water that replaced a significant piece of ageing water main crossing the Alamein railway line east of Melbourne was recently the runner up at the Victorian CCF Earth Awards 2014.
A condition assessment revealed the 2200 metre water main pipe, originally constructed in 1929 with riveted wrought iron plates, was in poor condition. The usually 6mm thick pipe was only 2.6mm thick in parts meaning parts of the pipe needed immediate replacement. Approximately 25m of deteriorating pipe was replaced with concrete lined mild steel pipe (MSCL) by contractors Downer Infrastructure and Kaycee Excavations.
Project Manager, Evelyn Yung said that if pipe failure had occurred, approximately 30,000 customers, including local businesses would experience water interruptions and the railway line would have potentially been flooded.
“The pipe needed to be replaced before peak demand during the summer, but it was important to avoid disruption to customer supply if possible. To do this the pipeline was isolated by inserting a new valve which allowed the diversion of water supply during construction” Ms Yung said.
The site presented a number of challenges as it was tightly bounded by high voltage power cables, a row of old cypress trees, a busy road bridge, steep embankment, bike track, a popular local café and an Op Shop. The local community were regularly kept informed about the project and its progress.
“As the pipe crosses a major rail line it was crucial to work with Metro Trains and negotiate a 50 hour window for the train shut down. If the work not been completed on time it would have caused major commuter disruption on the following Monday. This narrow window created additional risks and pressure due to the tight time frames and unpredictable Melbourne weather conditions. Critical works were also postponed due to the AFL Grand Final weekend, reducing the buffer period for the project” said Ms Yung.
“To carry out the work safely two Franner Cranes were used on the side of the road bridge and under the high voltage cables for lifting to eliminate the risks of intruding into the power line no-go zone and damaging the cypress trees. A scaffold-supported platform was also used instead of a boom lift under the pipe to support the structure. This provided unrestricted access for the site crew and various trades to carry out their works concurrently but safely and efficiently.
“The work was part of an ongoing commitment to improve water infrastructure in our service area. We know that to keep providing a good service to customers we need to regularly maintain and upgrade infrastructure such as the pipes and pumps delivering that service. By installing a new modern pipe once the old one had reached the end of its operational life we are investing in the future of a reliable water supply for the area” said Ms Yung.
