Bioretention

We supply certified bioretention sand and gravel blends for all layers of a basin which comply with FAWB, WSUD and Water By Design specifications and guidelines. Our bioretention media is tested at an independent laboratory to ensure quality and consistency.

Bioretention systems treat stormwater by filtering runoff through planted vegetation and percolating (drip feeding) the runoff through a filter media. This on-site filtration decreases the volume of runoff from a drainage area which ultimately reduces the required size and cost of downstream stormwater management facilities. Additionally, the on-site filtration removes excess nutrients and heavy metals from entering waterways and downstream water treatment plants.

River Sands produces specialised bioretention media which fully comply with Facility for Advancing Water Biofiltration (FAWB) and Water by Design specifications and guidelines. Blended onsite in batches of 600 tonnes, each batch has a sample tested by an independent lab for compliance in accordance with FAWB and Water By Design specifications. We pride ourselves on pioneering the supply of certified bioretention media within Australia, and our products are trusted by hydro and civil engineers to achieve results the first time.

Certificates of compliance for each batch supplied are shared upon delivery of the material to the job site. Rest easy knowing your certified bioretention media will enable a seamless handover of your project at the completion of building.

River Sands bioretention media has been used in local and government projects, commercial and industrial projects across Australia since 1999 with consistent and long-term performance success. All of our bioretention media can be available in 1 tonne bulk bags with sufficient notice.

Filter Media layer

The role of the filter media layer is to remove pollutants and support vegetation. Bioretention systems treat stormwater by filtering runoff through planted vegetation and percolating the runoff through filter media. River Sands Filter Media is a sandy loam which has high permeability when compacted and is designed to promote a functional filtration system. Consisting of amended natural siliceous sands graded to a consistent size, strength and spherical shape coupled with our manufacturing process, our Filter Media has tighter tolerances.

River Sands Filter Media product is guaranteed to safely meet a Hydraulic Conductivity (HC) of 100-300mm / hour. Additionally, when you purchase our Filter Media, you can be sure that uniformity co-efficients for the filtering material are fully tested, certified and approved prior to delivery.

Key attributes

• Engineered, amended natural siliceous sands graded to a consistent size, strength and shape
• Free from acid sulphate soils, rubbish, deleterious material, toxicants, declared plants and weeds
• Contains a minimum of 3% high quality organic matter from a long-term carbon source
• Saturated hydraulic conductivity of 100-300mm / hour. If higher hydraulic conductivity or increased organic matter is required please speak with the River Sands team.
• Low levels of orthophosphate
• Meets all FAWB, WSUD and Water By Design specifications and guidelines

River Sands can produce higher filter media with more than 5% organic matter. Please speak with our team if you have specific requirements for your project’s filter media.

Transition Media layer

Beneath a filter media layer, the transition media layer is used to prevent the filter media moving into the drainage media layer and the perforated underdrains. River Sands Transition Media is an engineered product consisting of amended natural siliceous sands that have been clean washed and graded to 1mm with less than 2% ‘fines’ content. The clean sand is able to support the bridging layer between both the filter media and drainage media as it has limited fine particles.

Key attributes

• Washed to remove fines which may cause coagulation
• Meets bridging criteria for particle size distribution to ensure smaller voids
• Meets all FAWB, WSUD and Water By Design specifications and guidelines

Drainage Media layer

The Drainage Media layer is made up of fine, washed aggregates and is usually up to 200mm deep. The drainage layer collects treated water from the base of the bioretention system and delivers it into the perforated under-drain pipes through infiltrated horizontal flows across the system. River Sands Drainage Media is an engineered product, consisting of fine 2-5mm gravel that has been clean washed and graded, with less than 2% ‘fines’ content.

Key attributes

• Washed fin gravel with limited fine particle content, less than 2%
• Has a minimum saturated hydraulic conductivity of 4000mm / hour
• Meets bridging criteria for particle size distribution to ensure smaller voids