Ecosol Sand Filter

Typically, the unit, which is designed to trafficable loadings, is located in industrial and commercial car parks, shopping centres, truck stops, freeways, and high-densityresidential housing estates.

The EcosolTM Sand Filter (off-line secondary solution) is an all-in-one primary and secondary filtration system that helps overcome the need for multiple treatment measures on catchments where space, or the drainage grade, limits the use of a bio-retention system.

Ecosol Sand Filter ecosol sand filter Ecosol Sand Filter Ecosol Sand FilterKey features

The EcosolTM Sand Filter is an all-in-one primary and secondary filtration system that helps overcome the need for multiple treatment measures on catchments where space, or the drainage grade limits the use of bio retention systems.

The unit is designed to treat 100% of incoming flows at a predetermined designed treatable flow rate, capturing and retaining pollutants conveyed from impervious areas in a rain event either at point of source or in-line. Independent testing has confirmed that the unit captures and retains more than 99% of pollutants larger than 2mm, 91% of Total Suspended Solids, 82% Phosphorous, and 45% Total Nitrogen as well as free floating hydrocarbons and heavy metals. It meets the stringent water quality objectives now being applied to most urban catchments in Australia today.

The EcosolTM Sand Filter consists of an inlet chamber with a removable capture basket for primary treatment. This significantly enhances the life of the sand media. It also consists of a forebay chamber to reduce flow velocities and a third chamber with sand filter media for removing finer particulates. A fourth chamber acts as an overflow by-pass and also reduces the potential for scouring in peak flows.

Compact and flexible and installed underground the unit is designed for high-density residential, commercial and industrial catchments.


Ecosol-Sand-Filter-1 ecosol sand filter Ecosol Sand Filter Ecosol Sand Filter 1


Key Dimensions

The EcosolTM Sand Filter is a multi-chamber engineered pre-cast concrete system consisting of an inlet chamber with a removable primary filtration basket into which stormwater enters from a conventional underground pipe. Gross Pollutants are captured and retained in this basket helping protect the engineered infiltration media from premature blocking.

The unique design of the inlet chamber also enables free-floating oils and hydrocarbons, such as cooking and motor oils that do not emulsify in aqueous solution, to be captured and retained, again helping protect the infiltration media.

The stormwater then continues into the forebay chamber which is designed to reduce flow velocity. This chamber is designed to have a permanent standing water level that helps it retain coarse to medium sediment larger than 125um. The flow then passes over the forebay weir and into the third chamber where it percolates downwards through the engineered sand media. The system is also designed with an overflow by-pass weir.

The table below highlights the key dimensions for the range of EcosolTM Sand Filter.





Secondary Filtration is undertaken using engineered layers of sand. The drainage layer consists of clean washed, fine gravel such as 2 – 5mm screenings and is designed to avoid migration of the filter media into the drainage layer. The drainage layer collects the treated stormwater and conveys it to the under drain pipes where it can then exit the system to the nearest drainage connection.



  • Engineered sand and gravel filter medias are supplied separately and installation is the responsibility of the purchaser.
  • Installation and operation of the EcosolTM Sand Filter is recommended once site conditions have stabilised.
  • The under drain collection pipes, geo-fabric, inlet primary filtration basket and Ductile Iron access covers are supplied factory fitted with the EcosolTM Sand Filter.
  • For optimal performance a temporary ponding depth of 200 – 300mm above the infiltration layer is recommended.

Collection Efficiencies

Sand filters have long been recognised as an effective, economical stormwater treatment system. They operate in a similar manner to bioretention systems are generally easier to maintain. Ecosol has designed its range of sand filters of  varying sizes to accommodate various flow capacities and site constraints such as space limitations. EcosolTM Sand Filter are unique as they incorporate a pre-treatment chamber and provide significantly greater access to the system than traditional sand filters; however the units main designed elements are based on the widely publicised and well published industry standards for sand filters. Additionally the range of EcosolTM Sand Filter has been extensively independently tested to validate the high performance characteristics of the system.

EcosolTM Sand Filters are sized to treat (based on a 100% impervious surface) catchments of 100 – 2000m2 Consideration is also given to site location, inlet pipe size, gradient and depth.

Particle Size Distribution Collection Efficiencies

Ecosol-Sand-Filter-4In order to determine a meaningful characterisation of the products collection efficiency, an extensive verification phase was undertaken by Avocet Consulting Pty Ltd, Ecosol Pty Ltd and EngTest (The University of Adelaide). To best summarise the capture efficiency results of extensive product testing a regression of the data points using a sigmoidal regression curve was selected as it provided a conservative fit to the data collected. Refer to figure 1 for details. Table 1 summarises these results.



Table 1 – Typical PSD Collection efficiency for the EcosolTM Sand Filter.



Figure 1 – Plot of collection efficiency sigmoidal regression line for the EcosolTM Sand Filter.

In recent years modern Water Sensitive Urban Design (WSUD) objectives and principles now applied to most urban development’s require more onerous water quality objectives (WQOs) specifically targeting the removal of suspended solids, nitrogen, phosphorus and heavy metals. The EcosolTM Sand Filter is an integral part of the treatment train providing essential primary and secondary treatment of stormwater within the one system.

Pollutant Removal Efficiencies



Table 2 – Suggested collection efficiency for the EcosolTM Sand Filter based on third party testing results.

Quoted Capture Efficiency (CE) values are intended as a general guide only, and are subject to site specific stormwater quality modelling (MUSIC), giving consideration to catchment size, rain events, pollutant concentrations and media configurations.

Reference – Facility for Advancing Water Biofiltration (FAWB), Advancing the design of stormwater biofiltration, June 2008.


Hydraulic Specification

Treatable Flow Rate
Treatable Flow Rate (TFR) is defined as the maximum flow rate through the EcosolTM Sand Filter before the flow overtops the designed by-pass overflow weir within the system. TFR is constrained by the infiltration capacity (Hydraulic Conductivity) of the engineered sand filter media. Extensive testing was undertaken on full sized units at actual designed media depths to avoid any possible error in interpolating TFR data.


  Table 1 – Summary of Treatable Flow Rates for the range of EcosolTM Sand Filter based on averaged flow per area result for the test unit. From these tests the optimal Treatable Flow Rate (TFR) and ponding depth for the range of EcosolTM Sand Filter is up to 1.6L/s/m2 at ponding depths of 200 – 300mm respectively.  


Cleaning and Maintenance

When designing the EcosolTM Sand 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, eliminating the need for direct physical access inside the unit.

As with all filtration systems the EcosolTM Sand Filter should be cleaned regularly. The cleaning frequency and the cost depends heavily on the catchment type and rainfall.

One of the key advantages of the EcosolTM Sand 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.

Ecosol Sand Filters are sized to treat (based on 100% impervious surface) catchments of 100 - 2000m2. Consideration is also given to site location, catchment type, size and condition.





Ecosol has a very competitive cleaning service. After each clean we provide a report detailing the volume and type of pollutants removed. We believe that it is in your best interests for Ecosol staff to clean and maintain the unit, not only because we are specialists, but also because proper monitoring and maintenance enhances the unit life significantly. Should you use another company to clean the unit, or undertake this work yourself, we request that it be conducted according to Ecosol’s specifications. Otherwise, you may invalidate your warranty, as damage caused by inappropriate cleaning procedures is not covered. The advantages of using Ecosol to clean and maintain your unit are that you get:

  • regular inspections of your unit
  • a comprehensive cleaning service with removal and disposal of all captured pollutants
  • a detailed report provided on completion of each clean
  • trained and experienced staff; and
  • remedial work completed, if required.




The EcosolTM Sand Filter is usually fitted onto pipes ranging in diameter up to 600mm in high density developments with little or no landscape areas and where there are space constraints or the drainage grade makes the use of bio-retention systems unsuitable.

Typically the units, which have been designed for trafficable loadings, are located in industrial and commercial car parks, shopping centres, residential housing developments and truck stops, freeways and maintenance yards.

Sand filters are often used to remove suspended solids, biochemical oxygen demand (BOD), total phosphorous, and faecal coliform bacteria. As the EcosolTM Sand Filter not only has a primary treatment capture basket for retention of gross pollutants such as litter, vegetative matter, and coarse sediment and a separate chamber for fine sediment and hydrocarbons, it is a particularly effective pre-screening system. This primary treatment significantly extends the life of the secondary treatment chamber which would otherwise become clogged with gross pollutants.

The primary and secondary treatment design of the EcosolTM Sand Filter enables it to be utilised as an efficient pre-screening system upstream of rainwater harvesting systems such as the EcosolTM Rain Tank, or on site detention systems.


  It can also be installed upstream of a wetland to enhance the life of the wetland reduce on-going maintenance.  

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