The CDS is a swirl concentrator hybrid technology that uses
continuous deflective separation – a combination of swirl concentration
and indirect screening to screen, separate and trap debris, sediment,
and hydrocarbons from stormwater runoff. The indirect screening
capability of the system allows for 100% removal of floatables and
neutrally buoyant material debris 4.7mm or larger, without binding. CDS
retains all captured pollutants, even at high flow rates, and provides
easy access for maintenance.
CDS is used to meet trash Total Maximum Daily Load (TMDL)
requirements, for stormwater quality control, inlet and outlet pollution
control, and as pretreatment for filtration, detention/infiltration,
bioretention, rainwater harvesting systems, and Low Impact Development
How CDS Treats Stormwater
- Stormwater enters the CDS through one or multiple inlets and/or a grate inlet.
- The inlet flume guides the treatment flow into the separation
chamber where water velocities within the chamber create a swirling
- Water velocities in the swirl chamber continually shear debris
off the treatment screen.
- The combination of swirl concentration and indirect screening
force floatables and solids to the center of the separation chamber
trapping 100% of floatables and neutrally buoyant debris larger than
the screen aperture.
- Sediment settles into an isolated sump while floatables and
neutrally buoyant pollutants are captured in the separation cylinder.
All pollutants remain in these sections of the unit until they are
removed during maintenance.
- Stormwater then moves under the hydrocarbon baffle, and the
treated water exits the system. The baffle acts as a wall for
hydrocarbon containment. It contains previously captured hydrocarbons
and prevents the agitation of hydrocarbons when high-flows spill over
the diversion weir.
- During high-intensity events, the internal diversion weir
directs a portion of flows greater than the design storm around the
treatment chamber and over an internal bypass weir.
- Treated stormwater exits the CDS via the outlet pipe.