Bio Retention


What is a Bioretention Basin?

Bioretention basins operate by filtering stormwater runoff through densely planted surface vegetation and then percolating runoff through a prescribed filter media. During percolation, pollutants are retained through fine filtration, adsorption and some biological uptake. The vegetation in a bioretention system is a vital functional element of the system providing a substrate for biofilm growth within the upper layer of the filter media. Vegetation facilitates the transport of oxygen to the soil and enhances soil microbial communities which enhance biological transformation of pollutants.

Why use a Rockslinger?

Coming in an array of sizes, bioretention basins can often be designed to cover thousands of square metres of area in order to cope with the amount of runoff in a particular area. The larger the basin, the more material is required which can often be a time-consuming process especially with the added challenge of ensuring that each transition layer of bio-media is installed to the correct specified depths. A vital part of the process.

Our Rockslinger machinery can efficiently and accurately install all specified bio-media materials to these basins without the need for tracked or wheeled machinery to access the interior of the basin area. This prevents issues with over compaction of the horizons which can lead to vulnerable areas within the basin and ultimately failure of the system itself.

What to consider when installing a Retention Basin:

  1. Design stage – Ensure the design of the basin has included the right depths and flow to achieve the end result of filtered and controlled water management.
  2. Vegetation choice – Look at plants that are suitable in dry and wet conditions.
  3. Specify Bioretention Filtration Media – this media evaluates the saturated hydraulic conductivity, suitability as a growing media, and the depth needed for the site. The media should be tested to FAWB and address the points in Adoption Guidelines for Stormwater Bio-filtration Systems (CRC WSC 2015).

The basin may include 3 layers:

  • Drainage Layer
  • Transition Layer
  • Filter media
  1. Installation – use The Hills Rockslinger to ensure the basin liner and pipework is not compromised my heavy machinery driving over it. The Rockslinger can install all three layers through the machine.
  2. Keep machinery off the Bioretention Basin, especially throughout construction.