Industry update – Finalised version of Appendix B Sediment Basin Design and Operation completed

Following approximately 18 months of industry use and consultation, the finalised version of the Appendix B Sediment Basin Design and Operation has been released. The document can be downloaded for free from the IECA Australasia website, along with supporting factsheets for basin design and coagulants & flocculants.
The primary change from the original 2008 version found within your current ‘white books’ is the inclusion of continuous flow sediment basins (referred to as Type A and Type B basins). Type A and B basins largely overcome the constraints associated with batch basins (such as Type D or former Type F) which are subject to overtopping during larger storm events and during consecutive rainfall events prior to treating and releasing.
The main changes between the Draft 2016 version and Final 2018 document are:

  1. Additional technical notes and description surrounding key basin elements, including possible retention of water and sediment storage zone depth
  2. Modifying the design process for sizing Type A basins based on jar testing rather than particle size and assumed settlement
  3. Changing the minimum free water zone depth to a default 0.2m (previously included a 10% of sediment storage volume requirement)

Now that this document is finalised its use and adoption within industry should be considered standard practice. To assist designers in sizing Type A and Type B basins, Topo has developed a simple spreadsheet, which is available to download for free from our website. Many of you have already downloaded this and provided great feedback regarding its use and benefit to you. In the coming weeks we will update the design tool to reflect the changes above from draft to final versions and send out to those who have previously downloaded it. If you would like to receive a copy please go to our website and download now and you too will get regular updates as they become available.
If you would like to find out more about designing and operating Type A, B and D sediment basins, Topo has specialised courses coming up in Brisbane and Darwin, which will cover how to size basin varieties (including using Topo’s design tool), how to adapt to site conditions and practical considerations to maximise the use and benefit of each basin type.

Kyle Robson