Client: City of Monash

Project Design:

Parsons Brinckerhoff

Contract Sum: $0.3M

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Holmesglen Valley Stormwater Biofilter (Wetland), Ashwood, VIC.

Works Included:

  • Wetland construction.
  • Excavation and removal of excess material.
  • Construction of clay liner.
  • Preparation of planting beds and drainage.
  • Construction of rain garden.
  • Rockwork.

Site Issues:

  • Removal of soil offsite.
  • Protection of surrounding trees.

A rain garden, or bioretention system, is a soil based system that treats stormwater runoff via filtration through a soil medium. The hydraulic and horticultural properties of the soil must be considered for the rain garden to be successful. Plants in the rain garden also increase the uptake of pollutants.

Rain gardens typically consist of the following layers; Mulch – retains moisture within the underlying filter media and suppresses weeds. Filter – layer of soil acts as pollutant filter and supports plant growth. Transition Layer – sand layer separating filter and drainage layers .
Drainage Layer – free draining layer containing perforated drainage pipe.