The Ecosol GPT (in-line end-of-line stormwater treatment solution) is a non-blocking, wet sump, tangential filtration system that has designed been specifically designed to filter pollutants conveyed in stormwater conduits by capturing and retaining all contaminants larger than 3mm up to a designed treatable flow rate (TFR). It can play and integral role in reducing pollution in urbanised catchments and help reduce the footprint of a total stormwater treatment train by providing essential pre-screening for downstream secondary and tertiary treatment systems.

Developed in 1996 and tested by the University of South Australia and also EngTest the commercial consulting division of the Adelaide University it remains today one of the most widely recognised and used stormwater primary treatment systems. Today as part of our continual product improvement program the modern Ecosol GPT is designed to provide high pollutant retention rates with little hydraulic impact on the drainage infrastructure.

Easily installed, the pre-cast, modular GPTs can be fitted to conduits of almost any size and shape, either within the drainage network or off-line adjacent to creeks or in open channels. Its range of applications include industrial and commercial sites, such as car parks, shopping centers, and wash down bays, residential developments, airports, freeways and as essential pre-screening for downstream secondary and tertiary treatment systems such as bio-retention or media filtration systems.


Proven system with over 20 year of field installations
Easily maintained by vacuum truck or by removable basket configurations
Captures and retains gross litter, sedimentation and hydrocarbons
Durable robust product engineered for the environment in which it operates
Suitable for installation into new developments or retrofitting to existing drainage networks
Minimum hydraulic impact and low head-loss system in peak flow conditions

At Ecosol we can provide you with a complete service inclusive of MUSIC modelling, structural engineered drawings, system installation, and commissioning and ongoing maintenance service with detailed reporting.

Ecosol GPT Configurations and Sizes - 2018
Ecosol GPT
Product Code
Pipe Diameter
Flow Rate (L/s)
External Dimensions
(L x W x D from inlet invert level)
Pollution Holding Capacities
Solid Pollutants >2mmFree Oils and GreaseWater
GPT 4200Up to 300mmUp to 51220 x 900 x 7500.23268667
GPT 4300Up to 525mmUp to 1202700 x 1350 x 7500.324691,181
GPT 4450Up to 600mmUp to 2603600 x 1650 x 10501.031,3473,348
GPT 4600Up to 900mmUp to 4704500 x 1950 x 13502.432,9947,211
GPT 4750Up to 1050mmUp to 7305600 x 2300 x 16504.835,71113,608
GPT 4900Up to 1350mmUp to 1,0506500 x 2300 x 19758.309,56722,768
GPT 41050Up to 1500mmUp to 1,4307450 x 2950 x 230013.1114,85035,262
GPT 41200Up to 1800mmUp to 1,8708630 x 3300 x 262519.5222,79351,698
GPT 41350Up to 1950mmUp to 2,3709700 x 3700 x 295027.7030,57872,495
GPT 41500Up to 2100mmUp to 2,93010680 x 4000 x 325037.9441,49198,317
GPT 41800Up to 2400mmUp to 4,21012730 x 4700 x 390065.3370,452166,836

Unit dimensions, treatable flow rates and holding capacities can vary depending on site specific requirements. Please consult with your local Ecosol representative for further details.

 Units are available in the following configurations:

  • In-Line, End-of-Line Systems
  • Off-Line Systems
  • Fixed Tangential screens for vacuum truck cleaning
  • Removable basket configurations for cleaning by crane truck

Please consult with your local Ecosol representative for further details on the most appropriate configuration and sized system for your site.

Gross Pollutant Traps (GPTs), such as the Ecosol GPT, are primarily designed to remove larger gross pollutants (>3mm) from stormwater at high treatable flow rates (TFR) and can play an integral role reducing pollution in heavily-urbanised catchments that discharge into our waterways.

Treatable Flow Rate

The Treatable Flow Rate (TFR) is the minimum flow that a GPT must treat, without by-pass, to achieve the desired pollutant capture criteria for a particular development style and catchment area. It varies dependent on geography, catchment type and size including pipe size and gradient. Typically, the Ecosol GPT is designed to treat flows between 1-in-3 month and 1-in-1 year Annual Rainfall Intensity (ARI) with greater flows by-passing the unit.

By-pass Capacity and Headloss

The range of Ecosol GPTs has been designed to cater for maximum flow by-pass at minimal headloss. The placement of any structure into a stormwater line will induce headloss. The extent of this headloss is a function of the velocity in the outlet pipe and the k factor adopted. The k factor must be representative of the type of structure and its operation during full-flow conditions as distinct from the TFR.

The Ecosol  GPT has one of the lowest k factors of any GPT currently available. Extensive independent testing has been carried out to confirm the unit’s k factor for a range of pipe and unit sizes based on full flow, worst-case scenarios. These tests show that the k factor can vary between 0.6 and 1.5 depending on the pipe size, configuration, gradient and the relative unit size.

The Ecosol GPT is designed specifically to provide essential primary treatment of stormwater runoff. It is an efficient, cost-effective solution to the ever-increasing problem of gross pollutants present in stormwater. Key to its success is the robust, engineered design and tangential screens housed in a pre-cast concrete pit that provides a significantly greater screening area than that of traditional direct screening trash rack designs. Further its large detention chamber enables gravitational separation to occur at low flow velocities retaining fine particulate matter conveyed in stormwater.

In 1997 and 1998 the Urban Water Resources Centre – University of South Australia (UniSA), was commissioned to undertake a series of tests on the widely-used Ecosol GPT (formerly known as the RSF 4000) to confirm the product’s performance. The tests measured the capture efficiency of the system under varying flow conditions and gradients and also the hydraulic headloss of the system under varying flows and gradients.

In October 1998 after further product development Ecosol commissioned Engtest the Department of Civil and Environmental Engineering at the University of Adelaide to undertake further testing on the system to confirm hydraulic headloss and capture efficiencies.

Concurrently Avocet Consulting was engaged to complete extensive CFD Modelling to determine Pollutant Trapping Performance and fluid hydraulic characteristics under varying flow conditions.

In early 2000 to mid-2001 as part of the company’s continuous product improvement program Ecosol engaged the services of Avocet Consulting to assess the Ecosol GPT‘s hydraulic performance, structural integrity, capture efficiency, treatable flow rates relevant to product sizing and scaling. Additional laboratory testing was also completed to monitor its performance as it filled and also to review the non-blocking, tangential filtration longevity of the system under varying flow conditions and percentage of fill.

Finally in 2013 EngTest Department of Civil and Environmental Engineering – University of Adelaide completed a series of additional product tests to further verify product performance and concurrently reviewed all past laboratory and field testing on the performance of the product to comprehensively determine its performance for current industry applications.

Ecosol GPT Capture Efficiency Performance Summary - 2018
PollutantCapture Efficiency Details
Gross Pollutants (GP)98%Particulate > 2000 micron
Total Suspended Solids (TSS)61%Particulate 20 - 2000 micron (mean averages)
Total Phosphorus (TP)29%Particulate and dissolved mean average efficiency less standard deviation
Total Nitrogen (TN)1%Particulate and dissolved mean average efficiency less standard deviation
Total Petroleum/ Hydrocarbon (TPH)99%In dry weather emergency oil spill situations
23%In a high flow event
Ecosol GPT Particulate Size - 2018
Particulate Size (Micron)Capture Efficiency
20 - 6023%
60 - 20067%
200 - 60094%
600 - 200098%

Capture efficiencies have been independently verified by laboratory and field tests confirming that the Ecosol GPT plays an integral part in the treatment train necessary to achieve generally-accepted water quality objectives (WQOs).

Figures quoted are mean collection efficiency statistics based on extensive laboratory and field testing data. It is important to note that the water quality CE values are indicative of potential field CEs given that product is designed primarily as a primary treatment solution providing physical tangential screening and the removal of chemical constituents is largely dependent on the chemical composition of the particles and the bonding of these chemical constituents to the surface of particles.

Further, finer and attached particle filtration performance of the product is also dependent on the body of pollutants forming a media already captured by the filter. Quoted CE values are intended as a general guide, please consult with your Ecosol representative for site specific product sizing and modelling.

As with all Gross Pollutant Traps, the Ecosol GPT should be inspected and cleaned regularly. The cleaning frequency, and the cost, depends heavily on the catchment size and type, the unit’s proximity to a waste facility, and rainfall.

The cleaning frequency may vary with local catchment conditions but the below figures are based on typical gross pollutant loads expected for typical commercial, residential, and light industrial catchments and provide a broad guideline about the catchment size and the number of cleans required annually. Gross pollutants include vegetation as well as anthropogenic litter but exclude sediment. The figures give consideration to the volume of pollutants in the unit and to eductor truck holding capacities and cleaning costs for a fully-loaded truck. In some instances, it may be cheaper to clean a unit more frequently than undertaking, say, annual cleans where the volume requires more than one truck load.

One of the key advantages of the Ecosol GPT is that it can be designed for cleaning by either vacuum (eductor truck) or removable basket (crane truck) method.

Ecosol GPT Indicative Catchment Size and Recommended Cleaning Frequencies - 2018
Ecosol GPT
Product Code
Pollution Holding CapacitiesOptimal Catchment Area (Ha)Recommended Cleaning Frequency
Solid Pollutants >2mmFree Oils and GreaseWater
m3LitresLitresHaPer Annum
GPT 42000.232686670.351
GPT 43000.324691,1810.501
GPT 44501.031,3473,3481.501
GPT 46002.432,9947,2113.601
GPT 47504.835,71113,6087.301
GPT 49008.309,56722,76812.501
GPT 4105013.1114,85035,26219.801
GPT 4120019.5222,79351,69829.501
GPT 4135027.7030,57872,49541.901
GPT 4150037.9441,49198,31757.401
GPT 4180065.3370,452166,83698.901

Cleaning frequencies are based on typical pollution loads of 0.280m3/ha/year for gross pollutants and 0.380m3/ha/year for Sediment generated on typical fully developed urban catchment. For larger catchments or during extended dry weather periods additional system cleaning may be required.

Ecosol specialises in the cleaning and maintenance of all Stormwater Treatment Devices including Vegetated solutions and would be pleased to assist you with your ongoing asset maintenance.

lvenessEcosol In Line GPT Off Line GPT