Any complete stormwater system is going to need plenty of help with pollutants, garbage, and even natural contaminants like silt, sand, and rotten leaves. There are several steps in the filtering of debris, starting at the surface and then heading underground. Then sometimes back onto the surface again, depending on the terrain and amounts of rainwater runoff involved. Here are a couple of types of debris separator units that can be employed to help treat the stormwater remotely before it enters a tributary.
The First Level Debris Separator Units Are Trash Capture
At the street surface there are several different types of capture mechanisms that can be used to stop most of the large trash items. Things like plastic bags, fast food containers, and other garbage are better caught on the street level. There they can be emptied by hand, or by the street sweeper as it passes by.
Hydrodynamic Separators With No Moving Parts
This separators work using the natural phenomena of water swirling and gravity to divide up the various types of contaminants and debris. Floating garbage, mostly litter and oils, swirl around the top and are jettison out an opening into a side chamber that can be emptied by vac truck. Sediments, on the other hand, tend to get pulled down the center of the swirl due to gravity.
The larger the particle and the more it weighs the faster it settles to the bottom. Since these separators have no moving parts they almost never will wear out and are inexpensive to make and install. They do need a certain amount of depth to work with but come in several different sizes, to accommodate most locations. These are also easy to maintain since there are no obstructions to the debris in the side containment vessel, they are quick to service with a vacuum truck and move on to the next manhole cover.
There are also chambers that are made to allow water to soak back into the water table from the stormwater captured there. These chambers also help filter the water with various splitters and other items that capture plastics as they pass by. Of course these will all have to be emptied by service trucks but it is quick work when all of the trash is concentrated in one place.
It’s important that all of the larger debris is caught all along the way and kept from entering the underground chambers as much as possible. Catch basins near fast food outlets are the worst since there can be a huge amount of trash thrown into the street on a daily basis. Then, when the rain starts, large piles can block entrances to the storm sewer system causing street flooding.
At some point people will need to take responsibility for their own trash and make sure it’s handled in the best way. Throwing any kind of trash into the street causes monumental problems, especially if everyone else is doing it too. The resulting blockages can disrupt the normal flow of stormwater causing a cascade of problems throughout the system.