ECOSOL NET GUARD

WATER SENSITIVE URBAN DESIGN & CONSTRUCTED WETLANDS

IN-LINE OFF-LINE INLET (UP TO 16500mm diameter RCP) PRIMARY TREATMENT SOLUTION

The Ecosol Net Guard provides effective primary treatment of stormwater flows thereby significantly enhancing the operational life of downstream secondary and tertiary treatment systems.

The system has been designed to provide a robust and durable cost effective in-line primary treatment system that captures and retains solid pollutants conveyed in stormwater conduits.

In developing this innovative primary stormwater treatment system careful consideration has been given to durability, longevity, cost, and maintainability. Key commercial technical features include:

  • low visual impact and energy footprint
  • designed hydraulics with proven performance and longevity
  • scalable, adaptable design
  • cost effective maintenance regime.

The Ecosol Net Guard is a compact primary filtration system that removes pollutants from stormwater flows. It consists of a pre-cast concrete pit that houses a strong stainless-steel frame with a removable heavy-duty UV-stabilised polyethylene filtration net for gross pollutant capture and retention. The filtration net is similar to that used in the highly-successful and widely-sold Ecosol Net Tech.

Once installed, under any flow, the unit will start capturing and retaining pollutants. The filtered stormwater passes through the net and downstream to the receiving waterway or to a secondary treatment system. It will continue to capture and retain gross pollutants until the filtration net reaches its designed holding capacity, or in the event of a major rain event, when excess flows will simply overtop the system, as designed.

The unit requires little or no structural change to the existing stormwater system, thereby reducing capital costs and minimising disruption to the general public during installation. One of the unit’s key advantages is its ability to operate effectively in both partially submerged and tidal environments where it will continue to operate effectively without any remobilisation of pollutants larger than the net apertures.

NET GUARD KEY FEATURES AND BENEFITS

Cost efficient and effective pre-screening, primary treatment solution
Visually unobtrusive, fully self-contained underground system
Easily maintained by crane or vacuum truck
Durable robust product, engineered for the environment in which it operates

At Ecosol we can site measure, fabricate, install and maintain your Net Guard making the whole process seamless.

The Ecosol Net Guard has been specifically designed as a pre-treatment system providing essential primary treatment upstream of wetlands, bio retention systems and detention basins.

Typical configurations include:

Ecosol NET GUARD DIMENSIONS - BOX CULVERT UNITS
Ecosol Net Guard Box Culvert Unit Dimensions and Configurations
Unit DescriptionMaximum Pipe
Diameter
Approximate Unit
Dimensions
(L x W x D from surface to invert level)
Approximate Unit
Weight
Approximate Maximum
Pollutant Holding Capacity
(mm)(mm)(t)(m3)
Single Module Net Guard900 x 9003600 x 1650 x 2000101.013
Double Module Net Guard1800 x 12006450 x 2250 x 2500163.500

The Ecosol Net Guard is able to be custom designed to suit most applications however the below tables provide a general guide on typical unit configurations for cylindrical and box culvert pipe applications.

Ecosol NET GUARD DIMENSIONS - CIRCULAR PIPE UNITS
Ecosol NET GUARD UNIT DIMENSIONS AND CONFIGURATIONS
Unit DescriptionMaximum Pipe
Diameter
Approximate Unit
Dimensions
(L x W x D from surface to invert level)
Approximate Unit
Weight
Approximate Maximum
Pollutant Holding Capacity
(mm)(mm)(t)(m3)
Single Module Net Guard10503600 x 1650 x 2000101.181
Double Module Net Guard16506560 x 2250 x 2500164.000

Treatable Flow Rates

The tables adjacent provide an indicative guide of the products treatable flow rate relevant to pipe sizes and gradient. 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 by-pass as designed.

Ecosol NET GUARD INDICATIVE TREATABLE FLOW RATE FOR CYLINDRICAL PIPES
Ecosol Net Guard Indicative Treatable Flow Rate for Cylindrical Pipes - 2018
Outlet Pipe DiametersDesigned Treatable Flow Rates (L/sec) at Grade
mm0.5 - 10%
375 (minimum size)65
450103
525151
600211
750369
825468
900582
1050 (maximum size)855
Ecosol NET GUARD INDICATIVE TREATABLE FLOW RATE INSTALLED ON BOX CULVERTS
Ecosol Net Guard Indicative Treatable Flow Rate Installed on Box Culverts - 2018
Outlet Culvert HeightDesigned Treatable Flow Rates (L/sec) at Grade (0.5-10%)Designed Treatable Flow Rates (L/sec) at Grade (0.5-10%)
mmBox Culvert (0.6m wide)Box Culvert (0.9m wide)
375 (minimum size)228
342
450299449
525377566
600461691
750644966
8257431115
900 (maximum size)8451267

In 2012 the University of Adelaide (Engtest Civil, Environmental and Mining) completed extensive testing and measurements of the products capture efficiency, hydraulic performance and durability at varying flow rates its and compiled a comprehensive product performance report (Performance Review of the Ecosol Net Guard).

Avocet Consulting CFD Modelling to determine Pollutant Trapping Performance and fluid hydraulic characteristics under varying flow conditions.

In September 2011 the Ecosol Net Guard was tested by Avocet Consulting to assess its hydraulic impact on the drainage network. The tests found that the unit had little or no hydraulic impact and that the overtopping design feature effectively eliminated the potential for flooding.

Antworks Engineering Structural Design Analysis of Guide Frame and Net Frame Assemblies

In July 2011, given that most generic trash racks fail when subjected to large flows, Ecosol engaged Antworks Engineering to model the EcosolTM Net Guard under a range of high flows to enable it to be designed to withstand critical peak flows full net conditions.

The results of this extensive product testing and verification phase is summarised in the table below.

Ecosol NET GUARD CAPTURE EFFICIENCY PERFORMANCE SUMMARY
Ecosol Net Guard Capture Efficiency Performance Summary - 2018
PollutantCapture EfficiencyDetails
Gross Pollutants (GP)93%Capture efficiency of gross pollutants by volume larger than the filtration netting apertures. Standard Netting consists of 50mm or 115mm apertures.

In practice and as the filtration net begins to fill with gross litter and vegetation thereby forming a filter media within the net, finer particulate and attached pollutants are also captured.

Ecosol NET GUARD SEDIMENT COLLECTION EFFICIENCY
Ecosol Net Guard Sediment Collection Efficiency - 2018
Particulate Size (Micron)Capture Efficiency
2000 – 600020%
6000 – 1600048%
>16000 90%

OPTIONS

To further enhance the systems pollution reduction efficiencies and to retain coarse sedimentation an additional diversion weir can be constructed in to the pit downstream of the filtration net thereby diverting coarse sedimentation conveyed in stormwater runoff to a secondary pre-cast concrete sump that utilises hydrodynamic and gravitational separation to capture and retain sediment and hydrocarbons entrained in stormwater runoff. This additional treatment capability effectively provides a primary and secondary treatment train system significantly enhancing water quality.

Initially Ecosol recommends that regular monitoring is undertaken monthly. Once the unit has been in operation for an extended period of time (say, 12 months) the monitoring schedule can be adjusted to reflect the actual operating conditions specific to the catchment. It is also recommended that the unit is inspected after every major storm event.

One of the key advantages of the Ecosol Net Guard is that a small crane truck or excavator can easily lift full filtration net for emptying. Alternatively it can also be cleaned by vacuum truck. All options eliminate any risks associated with manually handling captured pollutants. In addition there is easy safe access to the filtration net as the grated access covers are removable thereby providing clear well vented access to all internal components for maintenance.

As the Ecosol Net Guard is a dry system there is a reduced likelihood of captured contaminants causing any significant adverse environmental impact or nuisance (such as odours and putrefaction). The key benefit of this primary treatment device is its low capital cost along with its low ongoing cleaning and maintenance cost.

Indicative Catchment Size and Recommended Cleaning Frequencies for the Ecosol Net Guard

Ecosol NET GUARD RECOMMENDED CATCHMENT SIZES & CLEANING FREQUENCIES
Ecosol Net Guard Recommended Catchment Sizes and Cleaning Frequencies - 2018
Ecosol Net Guard Product CodeMaximum Pipe SizeGross Pollutants Holding CapacityOptimal Catchment Area (Ha)Recommended Cleaning Frequency
mmm3HaPer Annum
Single Module Net Guard - Cylindrical Pipe1050RCP1.1814.201
Double Module Net Guard - Cylindrical Pipe1650RCP4.00014.01
Single Module Net Guard - Box Culvert900 x 900 RCBC1.0133.601
Single Module Net Guard - Box Culvert1800 x 1200 RCBC3.50010.801

Cleaning frequencies are based on typical pollution loads of 0.280m3/ha/year for gross pollutants. Excludes coarse sedimentation typical urban pollutant loads.

lvenessEcosol Net Guard