North West Growth Centre Wastewater Transmission

Lend Lease (formerly Abigroup)

Box Hill, New South Wales, Australia

Diona was contracted by Lend Lease (formerly Abigroup) to construct new wastewater transmission assets throughout Sydney’s northwestern suburbs for the Sydney Water Corporation.

The North West Growth Centre forms part of the NSW Government’s Metropolitan Strategy, which anticipates an additional 640,000 homes to accommodate Sydney’s population of 2031. Ultimately the project allows for the residential development of the Riverstone, Box Hill and Vineyard areas in Sydney’s north-west.

The works under this contract included:

  • Installation of 6.5km of primary gravity sewer pipeline—varying in size from DN900 to DN225—alongside a creek at depths of up to 7m
  • Construction of 50 in-situ maintenance holes ranging from 1.8m to 1.2m diameter
  • Construction of an emergency relief chamber within a pump station
  • Two trenched creek crossings at depths of 6m
Risks and challenges

With the installation of the gravity sewer main, the most challenging component of the project was adverse weather and ground conditions. A particular challenge arose when the creek broke its banks and rose in excess of 4m, submerging the entire pipeline and construction easement. As our teams were building concrete-encased creek crossings at a depth of 6m, the water charged ground could have posed a major problem, but with the aid of three 6-inch pumps, our crews negotiated the creeks and the obstacles with ease.

The project required a large volume of high-risk work, including deep excavations, bad ground conditions, and confined spaces. However, due to a cooperative workplace safety culture, there was no lost time injuries (LTIs) or environmental incidents throughout the project.

Despite some delays due to extreme weather, the project was completed several weeks before the commission deadline.