What is a Buoyant Flow Control Device (BFD)?
A Buoyant Flow Control Device (BFD) is an orifice or weir suspended from a float at a fixed distance below the water surface so as to maintain a constant pressure over the weir or orifice such that it produces a constant discharge rate regardless of the water surface elevation.
How can a Thirsty Duck BFD make a detention pond smaller?
The required detention volume is the difference between the inflow rate and the outflow rate over time. Fixed weirs and orifices only discharge the maximum allowable rate when the water surface in the detention pond reaches it's highest design level. Thirsty Duck BFD's achieve the maximum allowable discharge rate at much lower elevations and maintain the rate at the maximum as the water level in the pond rises and falls. Since the Thirsty Duck BFD maximizes the outflow rate for an extended duration of time, the required detention volume is minimized.
Can I get a Permit for a Thirsty Duck BFD?
Thirsty Duck BFD's have been successfully permitted in Washington, Florida, South Dakota and other northwestern states. The TD series is approved for use by the Washington State Department of Transportation (WSDOT).
Does Thirsty Duck affect water quality?
Thirsty Duck BFD's are not BMP's in and of themselves. They are used to facilitate BMP's. Since Thirsty Duck minimizes the total system volume required to attenuate peak discharge rates, a greater portion of available system volume can be used for water quality treatment without degrading the flood attenuation characteristics of the system.
All Thirsty Duck devices are configured to prevent the discharge of oils, greases and other floating debris. The TD and ER 200 Series devices are both self skimming.
Does a Thirsty Duck BFD require additional maintenance?
Thirsty Duck BFD's are fabricated from high quality materials selected to withstand the stomwater system environment. There are no active mechanical parts and the devices feature “frictionless” operation. As with any control device, regular inspection and periodic debris removal should be a part of any maintenance program.
Is Thirsty Duck classified as an “Operable Structure”?
Thirsty Duck is passively operated and does not require any human intervention to operate.
(Buoyancy does all the work!)
How is Thirsty Duck protected from tampering and vandalism?
Thirsty Duck recommend installing TD Series devices in a standard DOT approved precast structure equipped with a locking hatch cover. The housing box should have inlets which are large enough to pass the required flow, but small enough to prevent any unauthorized intrusion. ER200 series models are designed to have a low profile and are much too heavy to be manipulated without the use of mechanical lifting equipment.
What happens if Thirsty Duck becomes clogged?
All Thirsty Duck devices are designed with easy access removal of accumulated debris.
Can Thirsty Duck withstand the stormwater system environment?
All Thirsty Duck models are fabricated from high quality, corrosion resistant materials selected to withstand the stormwater system environment.
How much does a Thirsty Duck cost?
Each Thirsty Duck BFD is custom fabricated. Contact a Thirsty Duck engineer for a pricing for your specific application.
How can I get more information or determine the benefits of installing Thirsty Duck on my project?
Design assistance will be happily provided by a Thirsty Duck engineer upon request. Contact us with information about your system.
How do I model a Thirsty Duck device with my hydrology and hydraulics software?
Thirsty Duck BFD's are modeled using a custom rating curve. See our modeling FAQ for general guidelines and specific instructions for several popular modeling packages. Thirsty Duck is currently working with the major software providers to include buoyant flow control technology in their packages.