Bioflters are an integral part of a total treatment train approach and are able to be applied at street scale to capture and treat stormwater runoff close to its source.

Stormwater Biofiltration Systems also commonly known as biofilters, bioretention systems and raingardens are configured as vegetated filtration systems with a collection pit and are designed to remove fine suspended solids and dissolved pollutants. They operate by filtering stormwater runoff through densely planted vegetation and then percolating the runoff through a prescribed porous filter media. Extended detention within the system acts to slow incoming stormwater, allowing suspended particles to settle. The stormwater then seeps through the underlying sand, soil or gravel filter media, where physical, chemical and biological processes contribute to pollutant removal.

The Ecosol Bio Filter is a modern, modular fully self-contained, linear stormwater treatment system that provides effective primary, secondary and tertiary treatment of stormwater flows in one compact device.

The system has been designed to provide a robust and durable cost effective aesthetically attractive kerb-side treatment system. The system is filled with porous filter media and planted with vegetation to remove pollutants from stormwater runoff using natural and physical processes.

In developing this innovative stormwater treatment system careful consideration has been given to durability, longevity, cost, and maintainability.


Available in wet or dry sump configurations
Designed hydraulics with proven performance and longevity
Scalable, adaptable design
Cost effective maintenance regime
Supplied as a complete system housed in its own pre-cast pit ready for installation

At Urban Asset Solutions we can site measure, fabricate, install and maintain your Bio Filter making the whole process seamless.

The Ecosol Bio Filter is a multi-chamber, engineered, linear, pre-cast concrete system.  It is typically designed for road side kerb easements with widths of between 1.2 – 1.5m and lineally up to 9.0m.  The system is supplied as a self-contained tertiary treatment system with all internal components pre-factory fitted  reducing significantly on-site time, an important factor given the costs associated with delays that can be caused by inclement weather.  Ecosol can design, manufacture or construct your Bio Filter specific to your site requirements and incorporate the following key elements necessary to ensure your system achieves optimal performance outcomes.

Pre-treatment Inlet Chamber

The Ecosol Bio Filter includes a Primary treatment chamber complete with litter basket for capture and retention of all pollutants conveyed in stormwater runoff larger than 200um and also includes an internal baffle system for retention of free floating hydrocarbons and settling chamber for gravitational separation of suspended solids and controlled inlet to the Tertiary Treatment Chamber.

Tertiary Treatment Chamber

The Ecosol Bio Filter tertiary treatment chamber consists of:

A Detention Zone

The Ecosol Bio Filter is designed to have a maximum detention zone of 300mm depth.

Infiltration Zone

This is the top layer for filter media (in the unsaturated zone).  This should be well graded material consisting of a Bio Retention Filter Media.  It should have particle size ranges present from 0.075 to the 4.75mm sieve (as defined by AS 1289.3.6.1 – 1995) and should be certified to the FAWB and Healthy Waterways guidelines.  The recommended depth of the infiltration zone for the Ecosol Bio Filter is 400mm.

Transition Layer

The transition layer shall consist of clean well graded sand material containing <2% fines.  The transition layer depth is typically 100mm consisting of a Bio coarse sand.

Submerged Filter Media Zone (optional to wet sump systems only)

The filter media (in the  submerged zone) should be well graded consisting of sand and carbon source.  It should have particle size ranges present from 0.075 to the 4.75mm sieve (as defined by AS 1289.3.6.1 – 1995) and should be at a typical depth of 300mm above the underdrain collection pipes.

Drainage layer

The drainage layer consists of clean washed, fine gravel such as 2 – 5mm washed screenings and is designed to avoid migration of the filter media layer material into the drainage layer.  The drainage layer collects the treated stormwater and conveys it to the submerged filter zone it should have an approximated depth of 150mm.

Underdrain Collection Pipes

The Under Drain Collection Pipes consists of 100mm diameter class 400 slotted or perforated collection pipes.  This has been specifically designed and modelled to ensure that water is able to freely drain away from the filtration media thereby not adversely affecting its performance.  In addition they are protected with a drain coil filter sock. Please refer to the above table for unit specific figures.


Careful selection of the most appropriate vegetation is necessary to ensure optimal performance of your Biofilter. Urban Asset Solutions can supply the system complete with appropriate plants ready for installation.  Alternatively you can select your own, however we recommend you consult with your local council to determined preferred species or refer to the Adoption Guidelines for Stormwater Biofiltration Systems Table 15 List of known species” released July 2015 as part of the CRC for Water Sensitive Cities.

Outlet Chamber

The Ecosol Bio Filter also includes an outlet chamber for discharge of treated stormwater form the system. This chamber includes flow control and an overflow primary treatment device.

Ecosol Bio Filter
Ecosol Bio Filter
Ecosol Bio Filter

The typical infiltration rate of a biofilter is 150mm/hour (0.04L/s/m2) for established vegetated zones.  Ecosol can assist with the most appropriate design and sizing of your biofilter specific to your site requirements.

Suggested removal efficiencies for the Ecosol Bio Filter are in accordance with the CRC for Water Sensitive Cities Adoption Guidelines for Stormwater Biofiltration System (July 2015).

PollutantCapture EfficiencyDetails
Gross Pollutants (GP)98%Particulate >200 micron
Suspended Solids (SS)86%Particulate
Phosphorous (P)79%Particulate
Nitrogen (N)15%Particulate
Heavy Metals55%Particulate
Total Petroleum Hydrocarbons (TPH)68%In dry weather emergency oil spill situations
Ecosol Bio Filter Capture Efficiencies - 2018

When designing the Ecosol Bio Filter careful consideration was given to ensure it was able to be maintained easily.  Multiple access points over each chamber have been incorporated into the design providing safe access.

As with all filtration systems the Ecosol Bio Filter should be regularly maintained.  The maintenance frequency and cost depends heavily on the catchment type and runoff quality and quantity.

One of the key advantages of the Ecosol Bio Filter is that the primary filtration basket can be manually cleaned. As this is most likely to need regular maintenance, having the ability to clean it manually significantly reduces ongoing third party maintenance costs.  The wet sump chamber containing captured coarse sediment and hydrocarbons will need to be cleaned at recommended intervals with a small vacuum truck removing all retained contaminants with each clean.

Regular inspection and maintenance is necessary to maintain the performance of your Ecosol Bio Filter. The below table provides a guide of key activities for maintenance of your system.

ItemActivityRecommended Frequency
Inlet Primary Treatment ChamberRemove by either manual or vacuum method all captured and retained gross pollutants from within the pre-screening inlet litter basketEvery 3 months or immediately after a rain event
Remove by vacuum method all cpatured and retained hydrocarbons and settled coarse sediment from within the inlet primary treatment chamberEvery 3 months or immediately after a rain event
Tertiary Treatment Chamber (Bio Filtration)Regularly check for agal biofirms that mey develop on the surface of the filter media leading to cloggingEvery 3 months or immediately after a rain event
Monitor ponding levels and infiltration rates following a rain eventEvery 3 months or immediately after a rain event
Remove any sediment build-up and scarify the filter media surface when necessaryEvery 3 months
Check for evidence of preferrential flow paths or scouring and replace filter media and place rock protection to eroded areas as requiredEvery 3 months
Check mulch and ensure even distribution and that it is clear of plant stems and replace as necessaryEvery 3 months
Inspect plant health and cover. Remove any weeds and water plants if necessaryEvery 3 months
Outlet (overflow) ChamberRemove by either manual or vacuum method all captured and retained gross pollutants from within the overflow litter basketEvery 3 months or immediately after a rain event
Remove from the overflow chamber by vacuum method any build-up of debris or sedimentEvery 3 months or immediately after a rain event
Structural ComponentsInspect all structural elements to ensure structural integrityAnnually
Ensure all inlets, outlets and overflows from the system are free from debrisAnnually
Ecosol Bio Filter Functions of each Chamber and Cleaning Frequency - 2018
lvenessEcosol Bio Filter