Warriewood Subdivision

A proposed in-fill development of approximately 80 homes is in the final stages of design documentation

The development requirements for stormwater management are quite stringent where we need to demonstrate that the post development peaks meet the pre-development peaks for a range of recurrence intervals (ARI’s) as well as the various storm durations. Our hydrological assessments considered climate change (e.g. increase in rainfall intensities) which informed an effective and sustainable subdivision stormwater infrastructure.
There are 3 separate OSD areas identified, however they must be able to operate together as each of the sub-catchments meet at one of the OSD basins. Therefore, system optimisation was a critical aspect of this assessment and was undertaken using DRAINS software.
The minor system is designed to convey the 20 year ARI is most of the network however some areas need to convey the 100 year ARI, prior to detention, as well as the climate change scenario with a 30% increase in rainfall intensity.
Our value management and clever design resulted in an overall reduction in OSD to achieve peak flows less than pre-development and safely convey the climate change floods.