Stormwater Equipment
There are two classes of stormwater devices: basic booms that capture about 80 percent of large pieces of litter or “floatables” and cutting-edge devices, such as hydrodynamic separators, that catch litter and sediment down to a hair on your head.
Hydrodynamic Separator
The newer, more sophisticated devices, such as hydrodynamic separators, catch 100 percent of litter and organic debris. In other words, they catch everything down to a hair on your head or 50 microns, including flood-causing sediments, litter, oxygen-lowering organics like grass clippings, branches, and parking lot pollutants (i.e. oils, litter, debris).
Hydrodynamic separators reside below the ground and when full you call in a vacuum truck. The vacuum trucks pop the manhole cover, insert the vacuum truck hose, suck it all out and take it to a landfill. In Pensacola, they call in the trucks a few times a year for each underground device. If the devices are not emptied, they automatically go into bypass mode. In Pensacola—once at the landfill--they dry it all out, separate out the litter, and reuse the sediments for fill needed in other projects. They cost between $10,000—to $300,000 depending on how much stormwater you need them to treat.
Hydrodynamic separator pictured above; the most sophisticated stormwater management device available.
Band-a-long litter trap with cage pictured above.
Band-a-Longs and Litter Traps
Bandit litter trap pictured above.
Band-a-longs with litter trap cages are perfect for in-stream stormwater solutions and can be placed in a dry river bed (like Ward Creek) where they will rise and fall with the water level and catch about 85-90 percent. They must be placed where there is easy access to clean them out. They range in cost from $14,000 for the smallest unit such as the Bandit and between $160,000-$300,000 for their larger band-a-long models. For the larger models, a crane is needed to lift the cage and empty the contents.
Booms
Oil booms with skirts are also used to manage stormwater debris and litter and catch about 80 percent. Once installed, they can be a challenge to access. Some are accessed by boat. Some cities build a bridge over them and hand pick from the top, while others put on chest waders and get in the water to collect the litter. Depending on access, a vacuum truck can be used to empty them.
Booms are high maintenance devices because if not cleaned out after each storm, litter merely goes under and over them. Booms are cheap to buy and install usually costing a few thousand dollars installed, and a broken boom can be replaced for under $1,000.
Basic litter-catching boom pictured above.