More stringent regulations will require treatment of stormwater at outlets like this one at Indian River Lagoon in Stuart, Fla.
Deflective separation technology

One popular system that uses precast concrete is CDS, a patented continuous deflective separation technology developed by Contech, of West Chester, Ohio. The CDS system screens, separates and traps debris, sediment, and oil and grease from stormwater runoff. Indirect screening capability removes all floatables and neutrally buoyant material without blinding.

Contech recently introduced a new configuration for in-line manhole configuration. The inlet design provides more ways to receive stormwater in a single treatment unit. The design features a forebay arc of 170 degrees that enables it to receive a single pipe or multiple inlet pipes anywhere along the semi-circle. The system also can be used as a catch basin or drop inlet, eliminating the need for additional structures.

This system features an oil baffle skirt that surrounds the nonblocking screening process to trap oil and grease. It also separates previously captured oil and grease from high bypass flows, preventing scour and possible reentrainment.

A system that can be retrofitted to existing concrete structures is the Snout, developed by Best Management Products of Lyme, Conn. The unit is a hooded outlet cover that is attached in the field and converts any sumped stormwater structure into a hydrodynamic separator. The company provides designs that can be attached to a catch basin wall over any type of pipe.

Since the model was introduced in 1999, the company has been researching ways to refine the separation process. It has added accessories like the Bio-Skirt, Trash Screen, and stainless steel deflector plates. The Bio-Skirt reduces bacteria and captures hydrocarbons, while the TrashScreen aids in containing litter and other waterborne objects.

The Snout can contain up to 95% of floatables while significantly reducing free oils and suspended solids. The combination of the Snout and the Bio-Skirt is an extremely robust delivery method to reduce many significant pollutants of concern including total suspended solids, gross particles, floatable trash and debris, hydrocarbons, and bacteria.

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