The Premarc Corporation - Products - CDS Technologies

OFFLINE UNIT

Untreated storm water is a recognized concern, both locally and nationally. As the source of storm water pollution grows, so do the ways and requirements for treating and managing storm water. Storm water runoff contains sediments, carcinogenic metals, pathogens, herbicides, pesticides, nutrients, debris, oils, trash - everything washed off of urbanized watersheds.

With patented continuous deflective separation (CDS) technology, the Offline Unit uses the hydraulic energy of water to concentrate, screen and trap many of these storm water pollutants. The Offline Unit removes 80% of total suspended solids (TSS) as well as 100% of floatables and neutrally buoyant material, plus oil and grease.

Process

Offline Units from CDS Technologies are designed to treat storm water flow ranges from 1 to 300 cubic feet per second (cfs) and higher. Treatment flow is diverted from a storm channel or pipeline, into the Offline Unit.

Storm water enters the Offline Unit's diversion chamber.
A diversion weir guides the flow into the unit's separation chamber where a vortex is formed.
The vortex separates most suspended solids in the separation chamber.
Suspended solids settle into a sump where they remain until they are removed.
Floatable and neutrally buoyant debris are retained in the separation chamber.
The stationary separation screen of the separation chamber does not become blocked because of the washing vortex, so liquid moves through the stationary screen cylinder.
Cleaned storm water moves out of the separation chamber and passes beneath an oil baffle.
Treated flow exits the unit into the diversion chamber downstream from the diversion weir, re-entering the storm water drain system.

Advantages:

The Offline Units are self-operating. Since they have no moving parts and are entirely gravity driven, maintenance is low. The screens and hardware are stainless steel, and resist corrosion.
These units have large sump storage capacities ranging from 424 - 1,396 gallons, depending on the model used.
The diversion weir is designed to bypass excessive flows without affecting the operation of the unit or storm drain system. Bypass flows do not wash any of the captured pollutants.
The unit's oil retention baffle effectively controls oil and grease. When sorbents are added, the permanent capture efficiency increases to 80 - 90 percent.
Capable of treating peak storm flows up to 300-cfs, the Offline Unit removes 100 percent of floatables.
This type of storm water treatment can be placed offline anywhere on the network with minimum retrofitting costs.
Since the units are compact and easy to place in confined areas, space requirements are minimal.
No moving parts.

Precast and Cast-in-place Offline Units

To meet different site requirements, the units are available in a variety of models, and configured either precast or cast-in-place. Fifteen precast models are readily available to treat flows from as little as 0.7-cfs up to flows of 64-cfs. Cast-in-place reinforced concrete units, using conventional construction techniques, can be built to treat flows up to 300-cfs. CDS units can also be placed in parallel or series to treat larger flows.

Maintenance

Depending on the site's pollutant loading characteristics, seasonal sump cleanout and annual inspection of the screen surface are the only requirements necessary to promote successful and efficient operation of the CDS Offline Unit. Since the units have large sump capacities, the sump can be cleaned with a standard vactor truck, sump basket or clamshell one to four times per year. The CDS screen and sump can be visually inspected for any remaining debris. There is no need for manned entry into the unit, which prevents any direct contact with captured pollutants.

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