Hayes Hill Branch Gravity Sewer
Yarra Valley Water
Melbourne, Victoria, Australia
Diona, with the support of our experienced pipelay and pit building crews, excavated and constructed the Hayes Hill Branch Gravity Sewer for Yarra Valley Water’s community development expansion in the northern suburbs of Melbourne.
Continuous improvements to every stage of the operation was a focus for the team to ensure success on a challenging project that required full depth excavation of medium to high strength basalt rock, and the installation of DN450 GRP pipe and maintenance holes at depths ranging from nine to 13 metres. The engineering team, in collaboration with the construction crew, designed a purpose-built access platform to provide safe access to the shoring system and access to the trench to undertake pipelaying and pit construction activities.
The project required type 4, 20mm crushed rock at approximately 65 tonnes per metre of pipe laid. Given the expected ground conditions of full depth basalt rock, as an alternative to hauling excavated material off-site, the project team recognised an opportunity to crush the excavated material and reuse it for backfilling the trench. Diona worked closely with stakeholders, Yarra Valley Water, VicRoads and the Whittlesea City Council to attain accreditation to produce a backfill material meeting the project design requirements.
The operation to crush approximately 60,000 tonnes of basalt rock included a jaw crusher, cone crusher and screen, and support from the pipelay crew to process the larger rock, and deliver a suitable mix to the crushers to obtain the correct grading curves. Local road movements were significantly reduced by an estimated 18 tandem trucks per day over four months.