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A high-efficiency advanced vortex separator designed for treating a large flow range while keeping headlosses low. The Downstream Defender® removes oil, fine sedimentm, trash and debris from stormwater in a footprint as much as half the size of conventional gravity separators.
The Downstream Defender® is the most advanced vortex separator available for the removal of sediment, oil and floatables from stormwater runoff. It combines specially designed polyethylene internal components in a standard concrete manhole structure. The Downstream Defender is proven to be more efficient than other structural treatment devices in as little as 1/2 the footprint and is the only separator with internal components proven to prevent pollutant washout.
The Downstream Defender has internal components designed to advance vortex separation by minimizing turbulence and headloss, increasing efficiency, and preventing washout of stored pollutants.
Watch the animation at right or the scale model testing below to see how it works.
Stormwater is introduced tangentially into the side of the vessel, generating a rotating flow that spirals around the outside of the dip plate.
Oils, trash and floatable debris rise to the water surface and are trapped in the oil and floatables storage volume.
As flow continues to spiral down around the dip plate cylinder, low energy vortex motion directs sediment inward along the benching skirt and into the protected sediment storage zone (brown zone).
The benching skirt and center cone redirect the rotating flow up and inward between the center shaft and dip plate cylinder away from the stored sediment. The outlet pipe discharges treated effluent from within the dip plate cylinder ensuring the longest possible residence time.
Some dimensions of the Downstream Defender cannot be modified as it relies on certain critical dimensions and minimum pipe sizes in order to function correctly. However, extended sump depths and other dimensional modifications may be available. Please inquire or submit a Request For Proposal to our engineering team and we will work with you to determine the best solution for your application.
To minimize turbulence within the treatment chamber, thus increasing the pollutant capture and retention efficiency.
Acceptable inlet/outlet pipe sizes vary by model size. Please refer to the sizing chart on the Downstream Defender flyer for acceptable pipe sizes.
In some cases, yes. The inlet pipes connect to the manhole on a tangent, so in some cases multiple inlet pipes cannot be accommodated.
No man entry is required. Maintenance is safe and easy with a standard vactor truck. Maintenance consists of removing sediments from the sump and floatable oils, grease, trash and other debris from the floatables capture zone. Watch the maintenance process:
The standard Downstream Defender models are designed to be “online” units that treat the entire flow, therefore there is no internal bypass. However, the Downstream Defender can be designed “offline” with an upstream bypass diversion structure.
The Downstream Defender is generally accepted for stormwater treatment or pretreatment in most areas of the United States. Please inquire for specific sizing criteria applicable to your area.
The Downstream Defender is 100% made in the US. The internal components are rotomolded polyethylene supported by a stainless steel frame. The chamber is a standard concrete manhole.
The Downstream Defender is available in 4, 6, 8, 10 and 12-ft diameters. The unit size needed for your specific application depends upon many factors including the level of treatment desired, the target pollutant and peak drainage system flow. Please inquire for more site-specific technical assistance.
The price varies slightly with location based on local precast concrete pricing, as well as design criteria such as overall height of the concrete manhole. Please request a proposal on the Inquiry page.
The Downstream Defender is available worldwide. In the United States, Canada and Mexico, contact Hydro International in Portland, ME. For availability in the United Kingdom, please visit our UK website. For all other international locations, please visit our international website.
General Arrangement drawings and Specifications are available from the Downloads tab.
No pump is needed. Based on simple hydraulics, the water level in the Downstream Defender will fill to the invert of the outlet during the first storm without any assistance required from a pump.
Removal efficiency is dependent upon the particle size and specific gravity of the pollutant, in addition to the flow rate of the stormwater runoff. Please submit a request to our technical team for assistance selecting the appropriate model size.
The installation process of a Downstream Defender is similar to installing a standard manhole. The inlet pipe is grouted in to the manhole chamber while the outlet pipe is connected with a Fernco coupling or a pipe boot. Submit a request for an installation manual from our technical team for additional details.
The Downstream Defender has been independently tested and has been shown to meet the requirements required for a Class II oil collector.
The Downstream Defender uses the principles of flotation and sedimentation to capture all floatable and neutrally buoyant trash.
Two Downstream Defender® devices were installed upstream of retention ponds to provide effective, reliable pretreatment.
Downstream Defender® devices pay for themselves by reducing expensive maintenance costs of large stormwater ponds.
The Downstream Defender® helps greater Boston's Greenbush Rail Line manage stormwater runoff wtih a heavy sediment load.
Downstream Defender® reduces expense of manufactured stormwater treatment devices.
The Downstream Defender® provides state-of-the-art stormwater treatment technology for a state-of-the-art sports complex.
York Hospital situated in historic York, Maine known for its natural beauty and scenic beaches, chose the Downstream Defender® to protect the fragile ecosystem of a nearby pond.
Heavy duty porous asphalt and Downstream Defender® are project’s key stormwater controls.
The Downstream Defender® meets stormwater treatment requirements while reducing cost and constrution time for massive project.
Review this worksheet before submitting a pricing inquiry to Hydro International.
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Your inquiry list allows you to create a list of products which you can later request further information about all at once, along with any questions you may have.
Click the image to watch the video
Click the image to View the animation
Go to Downstream Defender Sizing Calculator
An online tool for design consultants who specify stormwater treatment manholes.
Download User Guide before getting started.
