Ecosol Silt Arrestor

The EcosolTM Silt Arrestor is a purpose-built pre-cast concrete modular storage pit into which water contaminated with solids and suspended sediment flows for later release at predetermined flow rates.

Key Features

The range of EcosolTM Silt Arrestors provide a purpose designed and built storage pit where water that is contaminated with suspended sediment is conveyed as runoff to the unit and then released at predetermined flow rates. The EcosolTM Silt Arrestor by design enables suspended particulate matter conveyed to the unit in flows to settle to the bottom of the pit where it is retained until the unit is cleaned.

silt arrestor Ecosol Silt Arrestor Ecosol Silt Arrestor 1

EcosolTM Silt Arrestor Standard features

  • pit is designed to class D (trafficable) loading classifications
  • supplied complete with gas tight, ductile iron, bolt down, solid top, class D access lids
  • inlet and outlet pipe penetrations to suit the required pipe size and type


Under Construction



Key Product Dimensions

Dimensions and Holding Capacities

The EcosolTM Silt Arrestor will treat 100% of all flows and have a holding capacity commensurate with the inlet pipe diameter and flows likely to be delivered to the system.

The following table (table 1) shows the EcosolTM Silt Arrestor dimensions and holding capacities for typical cylindrical pipe applications.


Table 1 – Pollutant Holding Capacities for the EcosolTM Silt Arrestor.

For larger silt arrestors with improved holding capacities please consult with your nearest EcosolTM office.
The pipe diameters listed are internal pipe diameters.


Table 2 – Key product dimensions and indicative weights.

  1. Depth below invert varies depending on inlet pipe diameter.
  2. Minimum drop refers to the minimum fall between the inlet and outlet pipe invert levels necessary for the system to operation to its designed specification.

Standard Features:

  • All pits are designed to class D (trafficable) loading classifications
  • All pits are supplied complete with gas tight, ductile iron, bolt down, solid top, class D access covers compliant with AS-3996 2006
  • All inlet and outlet pipe penetrations are provided to suit the clients requested pipe size and type.

Available Extras:

  • Pre-cast access risers are also available for units with greater depths than the nominal unit’s standard wall height
  • Internal acid resistant epoxy coating is available on request
  • Vent connections are able to be cast-in on request
  • Step irons available on request
  • Weepholes (40mm diameter) can be included if required at the base of the pit.

Collection Efficiency

Industry testing of typical silt arrestors (also known as gravity separators) indicates that they can remove between 50% and 60% of Total Suspended Solids (TSS) down to 10 micron when the system is appropriately sized allowing for sufficient particle settling times within the device. It is therefore important to appropriately size your device relevant to rainfall intensities and catchment area. The effective capture of TSS also results in the capture of attached particulate nutrients.

The EcosolTM Silt Arrestor also provides removal of debris, free floating hydrocarbons, trash and other floatables conveyed in stormwater flows that do not emulsify.

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


Suspended solids (silt and sediment) from surface run-off are conveyed to the EcosolTM Silt Arrestor by the inlet pipe. Once trapped within the unit baffles slow the flow velocities thereby providing settling time for varying particles. Filtered stormwater is then discharged via the outlet pipe back into the drainage network with the solids settled and retained at the base of the unit.

The grading of suspended sediments entering the EcosolTM Silt Arrestor is important in determining settling velocities and to assist you in determining the appropriately sized silt arrestor for your project. The estimated standard settling time of particles ranging from 0.07 - 0.20mm is approximately 5 – 10 minutes. As a guide, traditionally larger units are typically installed in industrial environments where the smaller 1,600 & 4,000, EcosolTM Silt Arrestors would normally be used in small commercial applications such as wash down bays.




The specified treatable flow rates are based on a standard settling time of 5 – 10 minutes for particles ranging from 0.07 - 0.20mm and maximum outlet pipe gradients of 1 – 3%.

It is recommended that the units designed by-pass capacity is equivalent to the units designed treatable flow rate as this prevents the re-suspension of settled material. The Maximum by-pass capacities quoted above have been provided as an indicative guide only to assist with the overall drainage design.


Cleaning and Maintenance

The EcosolTM Silt Arrestors can be easily inspected from the surface using a dipstick method to determine the percentage of fill (settled sedimentation volume).

It is recommended that your EcosolTM Silt Arrestor is regularly cleaned out of all sediment and at a minimum should be cleaned before the silt level reaches 70% of its designed holding capacity. Cleaning is by vacuum method using commercial eductor trucks. Cleaning of the unit is completed from the surface level by moving the snorkel over the retained silts and sediment.

Careful consideration to the provision of functional and safe access for plant and personnel for maintenance, replacement and cleanout purposes should be considered as part of the planning phase. Ecosols range of Silt Arrestors have been specifically designed to provide ample access to all areas of the unit for cleaning and maintenance requirements and  also incorporates lockable access covers that prevent entry of unauthorised persons.

Cleaning and Maintenance
One of the key advantages of the EcosolTM Silt Arrestor systems is that the units are easily cleaned from the surface by eductor truck (vacuum method). This eliminates any risks associated with manually handling captured pollutants or confined space access.

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


Cleaning frequencies indicated are based on typical sedimentation loads anticipated for standard commercial, residential and light industrial catchments.

Aesthetic Considerations
As the total system is designed to be installed underground the surface footprint is minimal. Consideration has also been given to ensure the selected access lids are constructed from materials of suitable strength and durability to resist anticipated loads and pedestrian slippage. They are also designed to be removable by hand and include a safe, secure locking mechanism to prevent unauthorised access to the device.

Life Expectancy
The EcosolTM Silt Arrestor has been designed to meet strict engineering guidelines and manufacturers’ guarantees. The reinforced concrete has an expected life span of 50 years.

The EcosolTM Silt Arrestor has a two-year warranty covering all components and workmanship. EcosolTM will rectify at no charge, any problems that fall within the warranty terms. However, damage caused by outside parties is not covered by the warranty. This includes instances where the client cleans the unit or employs another company to do so, and damage is caused by inappropriate cleaning procedures.



The EcosolTM Silt Arrestor is designed specifically for use in commercial, industrial and transportation land uses and is intended primarily as a pre-treatment measure for high-density sites, or for use in hotspots, such as truck or vehicle wash down bays and areas with high traffic loadings.

Suitable applications for the EcosolTM Silt Arrestor include:

  • pre-treatment for other structural controls
  • parking lots, streets, driveways, truck loading areas
  • fleet maintenance yards
  • recycling or salvage yards and
  • commercial vehicle washing facilities.

Ecosol Silt Arrestor Technical Specification

EcosolTM Silt Arrestor Technical Specification

Ecosol Silt Arrestor Installation Guides

EcosolTM Silt Arrestor 1600L - Installation Guide

EcosolTM Silt Arrestor 4000L - Installation Guide

EcosolTM Silt Arrestor 8000L - Installation Guide

EcosolTM Silt Arrestor 13500L - Installation Guide

Ecosol Silt Arrestor Maintenance Guide

Ecosol Silt Arrestor Maintenance Guide PDF

Ecosol Silt Arrestor Interactive PDF

EcosolTM Silt Arrestor - 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 (3.4mb)

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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