Ecosol Trash Rack

The EcosolTM Trash Rack (in-line/end-of-line primary treatment solution) is a modern primary treatment direct screening system for locations where conventional GPTs are not suitable owing to cost or space constraints.

The EcosolTM Trash Rack (in-line/end-of-line primary treatment solution) is a modern primary treatment direct screening system for locations where conventional GPTs are not suitable owing to cost or space constraints.

Key Features

EcosolTM provides preliminary civil engineering, hydrology and customisable trash rack designs to suit almost any application. It also offers a turnkey service including site survey, manufacture, installation and maintenance.

Similarly EcosolTM has also developed a standard modular trash rack system suitable for most applications. The EcosolTM Trash Rack is a robust and modern primary treatment stormwater filtration system for use where there are cost or space constraints, or specialised cleaning equipment is not available. The unit captures and retains more than 93% of solid pollutants larger than >2000μm, although, in practice, it has been found to collect much smaller particles, including fine sediments.

Easily installed, the unit’s simple design overcomes any adverse hydraulic impact traditionally encountered with direct screening trash racks that often block in first flush flows. By incorporating filtration nets into the design its operating life is significantly improved with an increased screening surface area and larger pollutant holding capacity.

It can be installed not only end-of-line at almost any pipe outlet discharging to beaches, rivers, and creeks but also in-line in open channels.

The EcosolTM Trash Rack consists of a stainless-steel frame with support legs and a removable heavy-duty UV-stabilised polyethylene filtration net that can be easily lifted out for cleaning and maintenance using a small crane truck. This overcomes the problem usually encountered with traditional, fixed direct-screen designs, which are often difficult and expensive to clean.

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Example of an EcosolTM stainless steel custom built designed and installed trash rack.


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  Standard modular EcosolTM Trash Rack System.
The EcosolTM Trash Rack has many features and benefits, some of which are listed below:
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1 For single module units only - Multiple modular units can be designed and fitted to significantly larger outlets.

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Key Dimensions

The EcosolTM Trash Rack is usually installed at drainage discharge points prior to the receiving waterway, enhancing not only water quality but also site aesthetics by stopping significant volumes of gross pollutants entering the natural waterway and damaging the existing marine life and vegetation.

The EcosolTM Trash Rack is a compact, efficient, and cost effective solution to the ever-increasing problem of water pollution. Key to its success is the robust, engineered structural frame and filtration net that provides a significantly-greater screening area than that of traditional direct-screening trash rack designs.

The table below highlights the key performance specifications for typically-sized single module EcosolTM Trash Rack units to suit cylindrical pipes up to 1050mm and for box culverts up to 900mm wide by 900mm high. Figures quoted are for single units - for multi-units multiply the figures by the number of single unit modules required for your site.1-4




  1. Individual modules are designed for maximum flows and pipe diameters up to 1050mm or box culvert of 1200Wx 900H mm - for pipe diameters and box culverts larger than those specified above contact your local EcosolTM office.
  2. Holding capacities, TFRs, and by-pass capacities indicated are for single units - for multiple units multiply the figure by the number of units required.
  3. The filtration frame and screen height is equivalent to 75% of the outlet pipe diameter or box culvert height and the total net length is 2.5m.
  4. By-pass capacity is based on the unit height not exceeding 75% of the discharging-pipes height.

Collection Efficiencies

Particle Size Distribution Collection Efficiency

In 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 wide scatter of data collected. Refer to figure 1 for results of 50mm netting tests and figure 2 for the 115mm netting tests. Table 1 below summarises these results.

Table 1 – Typical PSD Collection efficiency for the 50mm and 115mm netting Net Guard products.    
Figure 1 – Collection efficiency sigmoidal regression line for the 50mm netting tests.    

Figure 2 – Plot of collection efficiency sigmoidal regression line for the 115mm netting tests.

Pollutant Removal Efficiencies

Ecosol recognises that modelling of stormwater treatment systems is an integral part of WSUD engineering procedures today. To assist you with your next project we are pleased to provide you with some indicative capture efficiency values for the Ecosol Trash Rack System.

Table 2 – Suggested collection efficiency for the 50mm and 115mm netting Ecosol Trash Rack products.

1The optimal collection efficiency for the Ecosol Trash Rack is at approximately 30 – 60% full. Accordingly, the removal of the constituents is dependent on the composition of the particles, and the bonding of the chemical constituents to the surface of the particles. Additionally the particle filtration performance of Ecosol Trash Rack is dependent on the body of pollutant forming a media already captured by the filter; therefore conservative capture efficiency ranges have been provided.

Quoted Capture Efficiency (CE) values are intended as a general guide only, please consult with your Ecosol representative for site specific product sizing and modelling.


Hydraulic Specification

Treatable Flow Rate

Treatable Flow Rate (TFR) is defined as the maximum flow rate through the EcosolTM Trash Rack before the flow overtops the net frame. TFR is constrained by the friction capacity of the inlet conduit, the capacity of the downstream conduit and the percentage of fill when the headwater is limited to the top of the filtration unit. For the purpose of assisting designers we have adopted conservative values.

The tables below provide an indicative guide of the products treatable flow rate relevant to pipe sizes. With an empty filtration net the resistance is negligible and therefore the treatable flow rate is higher. However when the filtration net is full of pollutants and impervious the Treatable flow rate of the unit approaches zero and the unit starts to operate in bypass as designed.

Cylindrical Pipe Treatable Flow Rates


Figure 1 - Treatable flow rate for the Ecosol Trash Rack as a function of pipe diameter for a circular inlet/outlet conduit.

Box Culvert Treatable Flow Rates


Figure 2 - Treatable flow rate for the Ecosol Trash Rack as a function of culvert height (for a range of widths).

By-pass Capacity

The unit has been designed to cater for full pipe flow by-pass. That is worst-case scenario with the filtration net full and impervious and with a maximum headloss (k factor) of 1.3. The by-pass capacity of the unit is determined by the depth of flow that can overtop the system. For the purpose of providing some guidance figures we have used conservative figures and assumed no backwater effect downstream of the unit.

By-pass Capacity (Cylindrical Conduits)


Figure 3 - Bypass capacity for circular conduits as a function of pipe diameter for a range of gradients and depths to pipe invert.

By-pass Capacity (Box Culvert Units)

Figure 4 - Bypass capacity for circular inlet/outlet conduits as a function of pipe diameter for a range of gradients and depths to pipe invert.    


Cleaning and Maintenance

As with all filtration systems, the EcosolTM Trash Rack should be cleaned regularly. The cleaning frequency, and the cost, depends heavily on the catchment size, type, estimated pollutant loading and rainfall. One of the key advantages of the EcosolTM Trash Rack is that a small crane truck can easily lift the individual filtration netting modules for cleaning thereby eliminating any manual handling risks and the need for specialised cleaning equipment. As the unit is a dry system there is a reduced likelihood of captured contaminants causing any significant adverse environmental impact or nuisance (e.g. odours and putrefaction).

A key benefit of the EcosolTM Trash Rack is not only its low capital cost but also its ongoing cleaning and maintenance cost. The EcosolTM Trash Rack can be easily inspected visually to determine whether it needs cleaning. EcosolTM recommends the unit is inspected every two months or after any major rain event to determine if it needs to be cleaned. Cleaning is recommended before the filtration net reaches its capacity to avoid flows bypassing the unit and discharging untreated to the receiving waterway. The figures below give a broad guideline about the catchment size and the number of cleans required annually for single module systems.





Cleaning frequency is based on typical gross pollutant loads anticipated for standard commercial, residential and light industrial catchments. Gross pollutants in this instance includes vegetation as well as anthropogenic litter, however excludes sediment. Cleaning frequencies may vary based on local catchment conditions and rainfall however the above theoretical cleaning frequencies are based on a pollutant loading of 40kg/ha/year.

All data provided in the above tables and figures are based on single units with 2.5m net lengths. For multiple module units please consult with your local Ecosol representative.

EcosolTM 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 Modular Trash Rack System

The EcosolTM Trash Rack is usually installed, free-standing, downstream of pipe or box culvert outlets or across open channels, regardless of size or shape without any adverse effect on its operational capability or any reduction in the hydraulic design of the drainage line. It is suitable for single or  multiple pipes and large open channels.

Efficient pre-treatment

An EcosolTM Trash Rack located upstream of a swale or detention basin provides essential primary treatment to remove both litter and vegetative pollutants thereby providing designers with cost-effective and efficient prescreening solution.

Cost effective stormwater treatment solution

The EcosolTM Trash Rack fills a gap in the available technologies for stormwater filtration. It is especially useful in those situations where there are space or cost constraints or restricted access for the specialised cleaning equipment needed with higher-end filtration systems.

Essential primary treatment for wetlands

Wetlands, such as that shown opposite, are an integral part of the treatment train providing tertiary treatment of stormwater flows by removing sediment, reducing bacterial contamination, and dissolved contaminant loads and trapping nutrients in reed beds. They also enable infiltration, and reduce the flow velocity of stormwater runoff. By design all wetlands swales require primary treatment as they cannot cope with large volumes of gross pollutants. The Ecosol Trash rack located upstream of the constructed wetland, will provide essential primary treatment to remove both particulate bound and soluble pollutants, including some forms of nutrients and is, therefore, an effective prescreening system for wetland designs.

Diverse design provides a simple stormwater treatment solution

Typically, the unit is located at outlets that discharge to beaches, rivers and creeks, open drains, and also man-made canal systems, where flows are usually of greater magnitude than those conveyed conventionally by pipe and where the multi-unit Ecosol Trash Rack is suitable in preference to more-costly and larger high-end engineered GPTs.

Custom designed, fabricated and installed trash rack systems

Ecosol also provides preliminary civil engineering, hydrology and customisable trash rack designs to suit almost any application. It also offers a turnkey service including site survey, manufacture, installation and maintenance.







Ecosol Trash Rack Technical Specifications

EcosolTM Trash Rack - Technical Specifications

Ecosol Trash Rack Installation Guides

EcosolTM Trash Rack - Installation Guide

Ecosol Trash Rack Maintenance Guides

EcosolTM Trash Rack - Maintenance Guide

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