The Premarc Corporation - Products - CDS Technologies

DROP INLET UNIT

Although catch basins are readily used across the U.S., few are ideally designed for sediment and pollutant capture like the Drop Inlet Unit from CDS.

The Drop Inlet Unit, or Precast Manhole Insert Unit, removes suspended solids, sediments, trash, debris, oil and grease along with floatable materials from storm water flows. The Drop Inlet Unit provides the lowest cost per cfs processed when compared to other structural Best Management Practices. Its patented non-blocking screen and non-mechanical function make it a low maintenance storm water treatment solution for very small developments.

Process

Using patented continuous deflective separation (CDS) technology, the Drop Inlet Unit effectively and efficiently separates solids from liquids.

Storm water flow enters the inlet grate or curb inlet and is channeled into the separation chamber.
It passes over a specially perforated separation screen in a hydraulically balanced condition, creating vortex solid separation.
Solids are then captured and retained within the central chamber. The fluid dynamics along the surface of the screen and the deflective characteristics of the screen prevent blocking.
Fluid passes through the screen and beneath an oil baffle before it exits via the storm drain outlet pipe.
Suspended solids, sediments and other solid pollutants, including oil and grease, trash and debris, are retained in a centrally located solids catchment chamber. The heavier solids settle into the sump.

Advantages

Installed underground, the Drop Inlet Unit is ideal for new construction sites as well as urban retrofit situations where space is limited and the drainage area is small.
This unit, like all CDS units, is entirely gravity driven with no moving parts or power requirements.
Its non-blocking screen overcomes the clogging and reduced efficiency experienced by direct filtration systems.
The Drop Inlet Unit is an effective fine solid separator, and no other BMP comes close to its assured removal of gross solids and neutrally buoyant material.
Independent test show that in addition to 80% suspended solids removal, the units trap virtually 100% of gross particulate material half the aperture size of the screen and more than 90% of the particulates one-third the aperture size.
A conventional oil baffle in the unit effectively controls oil and grease in the storm water flow. With the addition of sorbents, the permanent capture efficiency is increased to 80 - 90%.

Specifications

Footprint diameter: 4.8 ft.
Variable Sump Capacity: 0.5 to 1.5 cubic yards
Treatment Capacity Range: 0.7 - 2.8 cubit feet per second

Maintenance

With its corrosion-resistant stainless steel screens and inert fiberglass inlet, the Drop Inlet Unit requires very little maintenance. As a general rule, CDS recommends removing solids with a standard vactor truck one to four times a year, depending on each site's pollutant loading characteristics.

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