Bioretention Filters clean the water that collects on impervious surfaces like sidewalks and parking lots. This accumulation of water is called runoff. Runoff usually occurs after rain storms and collects pollutants like pesticides as it travels downhill. Bioretention filters use variations of soils and plants to filter such pollutants from the water before it reaches main bodies of water, much like a coffee filter. When polluted water is diverted into a bioretention filter, it first travels through a sand bed slowing down the velocity of the water and minimizing erosion. After the water is evenly distributed along the ponding area, the indented area that collects the runoff, it slowly travels through layers of soils and rocks that act as multiple kinds of “coffee filters” and releases back into the water system over the length of four days. Having a Bioretention Filter at NCC protects the environment from any pollutants that may accumulate on NCC’s sidewalks, like spilt coffee or soapy water.

EPA. Storm Water Technology Fact Sheet: Bioretention. Washington, D.C.: U.S. Environmental Protection Agency, 1999. Water. Municipal Technology Branch U.S. EPA. Web.