One of the biggest problems with water turbidity is also, coincidentally, its smallest problem. The size of a sediment particle is what makes it easier or harder for the particle to become suspended in water. Tons of tiny, microscopic grains of dirt can easily become suspended in water, inevitably creating a turbidity problem in that water. Turbid water carried through a stormwater system and back into a natural waterway can negatively impact the local habitat for fish and other wildlife. One way that we try to combat turbidity in water is by trying to make the particles larger. The use of flocculants is one way to accomplish this.
What is flocculation? Basically, the application of certain chemical agents into the water, add even minor velocity to the water, and the agent will promote the attraction of the tiny particles to each other – ultimately creating larger particles that are heavy enough to settle to the bottom. Flocculants can be used by placing the chemical into a body of water on-site, such as a stormwater pond or a sediment trap. Because a lot of flocculants are activated through some sort of movement, you can also place the flocculants along a channel, pipe, or outfall to that the water is treated as it passes over them.
Flocculants are incredibly versatile and can be implemented with several different BMPs to create the ideal system for your site. The flocculant can be placed along turbidity curtain to create a suspended and fixed system to help in a flowing water situation. You can place solid flocculant blocks along culverts, channels, or pipes in dewatering systems as they drain to holding ponds or sediment tanks. You can also use flocculants before de-silting to make the sediment easier to remove from sediment basins, ponds, or other collection areas. We can easily implement flocculants in to any erosion control or dewatering plan to increase the effectiveness!
It’s important to note that although flocculants are super effective when it comes to reducing turbidity, they come in many different forms; some being potentially harmful to the natural environment. Too much Alum (Aluminum sulfate), for example, can be potentially harmful to fish. Finding the correct product and correct quantity is important to ensure no harm comes to the local environment. Having a qualified inspector on site regularly for NPDES inspections will help monitor the situation and can quickly notify if there are any potential issues, potentially avoiding any dangerous situations.