Ecosol Net Guard

The EcosolTM Net Guard (in-line/end-of-line primary treatment solution) is an efficient pre-screening filtration system that enhances the operational life of downstream secondary and tertiary treatment measures.

The EcosolTM Net Guard (in-line/end-of-line primary treatment solution) is an efficient pre-screening filtration system that enhances the operational life of downstream secondary and tertiary treatment measures.

Key features

The EcosolTM Net Guard 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 >600μm, 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. It can be installed at almost any pipe outlet discharging to beaches, rivers, and creeks and also in-line. Installed underground in its own compact pre-cast concrete pit it is visually unobtrusive and safe from tampering or vandalism unlike many above-ground trash rack systems.

The EcosolTM Net Guard consists pre-cast pit that houses a stainless-steel frame 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.

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Operation and Applications

Net Guard Operation ecosol net guard Ecosol Net Guard The Ecosol Net Guard2The EcosolTM Net Guard consists of a pre-cast concrete pit that houses a strong stainless steel frame and removable heavy-duty UV-stabilised polyethylene filtration net (either 50mm or 115mm apertures) that can be easily lifted out using a small crane truck.

The unit will continue to capture gross pollutants until the net reaches its designed holding capacity, or in the event of a major rain event, when excess flows are designed to simply overtop the system. This facility helps eliminate any adverse hydraulic impact or potential for flooding during peak flow storm events.

Applications

The unit can be installed within most drainage lines to provide essential pre-screening of stormwater flows as an integral part of any treatment train. As the unit is underground in its own compact pre-cast concrete pit it is visually unobtrusive and safe from any tampering or vandalism.

Hydraulics

The unit can treat 100% of all flows up to its designed TFR and withstand a full-pipe flow by-pass. Headloss (k factor) varies between 0.8 and 1.3 depending on site-specifics. Even in the worst-case scenario (full-pipe flow and full net effectively making it impervious), the increased width within the chamber limits the headloss with little or no impact on the drainage network’s hydraulics.

"Configurations
The EcosolTM Net Guard suits pipes and box culverts ranging in diameter from 375mm to 1050mm and up to 1500mm x 900mm RCBC for single units and can also be installed as a multi-unit configuration on larger outlets.

Cleaning and maintenance

The unit’s simple design and removable net makes access easy. It is best cleaned using a small crane truck, which eliminates any manual handling risks and the need for specialised equipment.

The cleaning frequency depends on the catchment type and size but, as a guide, a unit serving a 1Ha commercial catchment will need cleaning about twice annually.

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Net Guard configurations and sizes ecosol net guard Ecosol Net Guard The Ecosol Net Guard4

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Key Dimensions

The EcosolTM 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.

 
 

Table 1 - Cylindrical unit configurations and key dimensions.

NetGuardgraph3

 
  Table 2 - Box culvert unit dimensions and configurations.  
 

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, EcosolTM 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 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 - Collection efficiency sigmoidal regression line for the 115mm netting tests.  
 

 
  Table 2 - Suggested collection efficiency for the 50mm and 115, netting Ecosol Net Guard products.  
 

1The optimal collection efficiency for the EcosolTM Net Guard 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 Net Guard 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 Net Guard 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.

 
 

Cylindrical Pipe Treatable Flow Rates

The tables below 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.

 
     
   
  Figure 1 - Treatable flow rate for the EcosolTM Net Guard as a function of pipe diameter for a circular inlet/oulet conduits.  
     
   
  Table 1 - Cylindrical Pipe Treatable Flow Rate figures for the EcosolTM Net Guard.  
     
 

Box Culvert Treatable Flow Rates

 
   
  Figure 2 - Treatable flow rate as a function of culvert height (for a range of widths) for a rectangular inlet/outlet conduit.  
     
   
  Table 2 - Box Culvert unit treatable flow rates (TFR).  
     
 

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 product must be installed as a straight thru pit. The bypass capacity of the unit is determined by the depth of the pit, and the outlet pipe diameter/size and gradient. 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 - By-pass capacity for circular inlet/outlet conduits as a function of pipe diameter for a range of gradients and pit depths (depth to pipe invert).

The below tables confirm the by-pass capacity of the EcosolTM Net Guard for various cylindrical pipe diameters at various grades and pit depths. This is based on worst-case scenario (full and impervious filtration net at full pipe discharge). The by-pass capacity of the unit is determined by the depth of the pit, and the outlet pipe diameter/size and gradient. For the purpose of providing some guidance figures we have used conservative figures and assumed no backwater effect downstream of the unit.

 
   
  Table 3 - Indicative Net Guard by-pass capacities with a 2.0m depth to invert for cylindrical pipe configurations.  
     
   
  Table 4 - Indicative Net Guard by-pass capacities with a 1.75m depth to invert for cylindrical configurations.  
     
   
  Table 5 - Indicative Net Guard by-pass capacities with a 1.5m depth to invert for cylindrical pipe configurations.  
     
 

By-pass Capacity (Box Culverts Conduits)

 
   
  Figure 4 - By-pass capacity for circular inlet/outlet conduits as a function of pipe diameter for a range of gradients and pit depths (depth to pipe invert).  
     
   
  Table 6 - Indicative Net Guard by-pass capacities with a 1.5m depth to invert for box culvert configurations.  
     
   
  Table 7 - Indicative Net Guard by-pass capacities with a 1.75m depth to invert for box culvert configurations.  
     
   
 

Table 8 - Indicative Net Guard by-pass capacities with a 1.5m depth to invert for box culvert configurations.

It is important to note that the values are merely indicative of the bypass capacities for specific instances of conduit gradient and pit depth (and culvert width in the case of a rectangular conduit). Consultation with Ecosol is recommended for applications not within the ranges outlined above.

Headloss (K Factor) and Pollutant Holding Capacity

Headloss is defined as the hydraulic energy loss (embodied by the pressure reduction) experienced by the flow through the unit as a function of the flow rate through the unit. The headloss is typically characterised by the minor loss K factor (which is the multiplier for the velocity head to determine the actual headloss).

Cylindrical Conduits

 
   
 

Table 9 - Indicative Net Guard headloss and holding capacity figures for cylindrical conduits.

Box Culverts Conduits (Based on 0.9 Culvert Width)

 
   
 

Table 10 - Indicative Net guard headloss and holding capacity figures for box culvert conduits.

The headloss at full pipe of peak flow discharge will vary depending on site specific conditions however in a worst case scenario (that is full pipe flow, surcharged condition, with full impervious filtration net) the maximum headloss k factor would be 1.33K.

 
 

Maintenance

One of the key advantages of the EcosolTM Net Guard is that a small crane truck can easily lift full filtration net for emptying. This eliminates 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 EcosolTM Net Guard is a dry system there is a reduced likelihood of captured contaminants causing any significant adverse environmental impact or nuisance (such as odors and putrefaction).

The key benefit of this primary treatment device is its low capital cost along with its low ongoing cleaning and maintenance cost.

Catchment Size and Recommended Cleaning Frequency

 
   
 

Table 1 - Indicative cleaning frequency for the Ecosol Net Guard.

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 2.0m net lengths. For multiple module units please consult with your local EcosolTM representative.

 

 

Applications

The EcosolTM Net Guard is usually installed in-line on stormwater single pipes or box culvert ranging in size from 300mm to 1200mm, although is suitable for larger pipes and box culverts in a multi-unit configuration. Available to suit pedestrian and trafficable loadings.

The EcosolTM Net Guard is an effective primary prescreening system that removes larger solids from stormwater, thereby extending the life of secondary and tertiary treatment systems, such as wetlands and vegetated swales, which would otherwise become clogged with gross pollutants.

           

Ecosol Net Guard Technical Specifications
 

EcosolTM Net Guard - Technical Specifications


 

Ecosol Net Guard Installation Guide
 

EcosolTM Net Guard - Installation guide


 

Ecosol Net Guard Maintenance Guide
 

EcosolTM Net Guard - Maintenance guide


 

Ecosol Net Guard Interactive PDF
 

EcosolTM Net Guard - Interactive PDF - Interactive 3D product drawing - the attached file allows the viewer to zoom in on the product, rotate the product and to view the product and components from all angles. Please note: This is a large file (23mb)

This interactive PDF can only be viewed on the latest versions of Safari or Internet Explorer and will require the latest version of Adobe Reader.


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