The project at 347 Calderwood Road consists of a 455 lot, multi-stage residential development located in the Calderwood Valley development in the Illawarra.

The Orion design team was engaged to undertake engineering due diligence and, in conjunction with the urban designer, optimise the yield and commercial returns across the site. The Orion design team was also engaged to prepare engineering documentation to support the DA submission.

The topography across the site was extremely challenging with natural grades in some areas exceeding 30 degrees. This meant that a number of scenarios were required to be investigated to ensure that the proposed roads met with Council standards whilst the grades across the residential lots did not result in inflated dwelling construction costs. The extreme topography was caused by the underlying Jamberoo sandstone, for which the volume of excavation needed to be minimised due to its extreme strength.

The Orion team undertook a thorough due diligence assessment prior to the commencement of detailed design, including obtaining additional geotechnical information, to create a profile of the high strength rock and create a design mesh across the site. Using this information, Orion was able to optimise the road layout to maintain balanced earthworks across the site whilst significantly reducing rock cut.

By utilising the enhanced rock profile at the detailed design stage, Orion was able to work collaboratively with the project urban designer to adjust the proposed lot layout, thereby reducing the excavation of the high strength rock by approximately 30,000 cubic metres. This resulted in a significant reduction in the anticipated construction cost without any detrimental impact on the lot yield across the site.

Civil & Stormwater Design,

Philip Byrum, Andrew Szymik