Storm water runoff typically collects pollutants, such as chemicals, grease, garbage, and bacteria from impervious surfaces such as roofs, parking lots, roads and sidewalks. Without a biofilter, these pollutants would enter and pollute the natural water system of ponds, streams and aquifers.
Prairie Med’s site contains various naturally vegetated areas which act as biofilters designed to decrease the quantity and increase the quality of stormwater runoff. Natural vegetation, with deep absorbent roots, collects, temporarily holds, filters and absorbs stormwater runoff and many of its pollutants before it is released into the natural water system. Prairie Med’s biofilters include:
RAIN GARDENS are a form of biofilter in a shallow depression, generally formed on a natural slope, planted with native plants and flowers. Like other biofilters, rain gardens are designed to decrease the volume and increase the quality of stormwater runoff. Rain Gardens are not a pond or wetland as water is typically absorbed within 48 hours after a rain event.
BIOSWALES are another form of biofilter typically found adjacent to or between parking spaces in a parking lot. While similar in design and serving the same function, bioswales are typically deeper and narrower than rain gardens. Like other biofilters, bioswales are designed to decrease the volume and increase the quality of stormwater runoff. Bioswale are not a pond or wetland as water is quickly absorbed.
DETENTION WITH FOREBAY AND MICROPOOLS is another naturally vegetated biofilter designed as a supplement to and located at the bottom of stormwater retention ponds. Through the formation of small wetland marshes and shallow micropools together with wetland vegetation, detention forbays and mircopools enhance the pollutant removal capability of the pond. Detention with Forebay and Micropools are unlike Rain Gardens and Bioswales in that they are ponds and can be wetlands; they are similar in function as they are also designed to decrease the volume and increase the quality of stormwater runoff.