Client: Cardinia Council

Project Summary:

The northern portion of Cardinia Shire Council is dominated by foothills of the Dandenong Ranges and its associated steep clay catchments. This topographical effect coupled with low levels of development and high vegetation cover had a profound influence on both the hydrology and hydraulics of the area.  These catchments resulted in fast response high velocity flows with an associated high erosion potential.

As a response to this Cardinia Council undertook a number of sediment capture and erosion reduction measures over a number of years, including the installation of rumble swales, capture pits, gravel basins and defined sediment pits. The scope of investigations was:

  • A thorough review of the literature with regard to the unsealed road runoff and possible mitigation solutions
  • Full Sieve analysis for all of the existing traps
  • Review of the possible impact/benefit of the existing traps
  • Review of road grading techniques and frequency on the traps

Key Findings:

Some of the key lessons found in this study include: 

  •  Maintenance – good road maintenance will reduce sediment issues, in particular the regular observation of table drains, beaching of potential erosion points, and identification of depositional zones.
  • Identifying the types of sediment that are important to a particular area, or potential receiving water reach is important in both the sizing, influential with regard to potential capture efficiency. 
  • Hydraulic influences – setup and local grades have a large influence on the settling properties. 
  • Cost – choice of sediment capture device will be influenced by level of intervention. 
  • Basic catchment calculations can save in maintenance requirements.

Key Features and Innovations:

  • Working with Council to understand the performance of assets