Environmental agenda goes underground

Early consultation undertaken by Melbourne Water, Yarra Valley Water and John Holland in the pre-construction phases was critical – and it is paying dividends as minimal complaints have been registered.From the outset the project recognised the need for strict environmental controls, particularly around noise. “One of our biggest challenges is running 24-hour operations in an urban environment,” Muley said. “The nearest neighbour to one of the sites has their house within metres of the site boundary, so the project team has constructed very substantial noise amelioration sheds which allows us to operate 24 hours. To date, they have been working very well.”“The tunnels are also reasonably deep and where we do have shallower tunnelling, it is typically underneath open space or roads. We are not expecting significant vibration issues, and so far it hasn’t been a problem – obviously we get vibration with blasting, but this has been very carefully controlled.”The John Holland shaft sites certainly are notable for their small construction footprint and, even more so, the lack of the noise and disruption of a typical construction site. The massive acoustic sheds feature sliding doors to trap sound during night shifts and allow 24-hour operations.“The impact of the whole project is minimal,” Muley said. “Noise and environmental impacts are controlled very well.”Nothing is being left to chance, with spoil from the tunnels also being treated. While the harder basalt is being transferred to a local quarry for re-crushing, the spoil from the EPB TBMs is being treated before it is transferred to landfill. The eight shafts established for the project will be sealed, with access for maintenance purposes only. “All you will see at the completion of the project is a shaft cover and the sites will be returned to their original condition,” Muley said.“Sewer tunnels are not as high profile as other tunnelling projects that have been constructed, but we are happy with that.”

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