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C. BIOFILTRATION <br /> Blofiftratlon systems use vegetation and/or sand and other natural filtration media to reduce pollut- <br /> ants in stormwater runoff. Filtration, Infiltration,ad- ~= �:•,:: <br /> sorption,sedimentaflon,and biological uptake of -f �� Wet Tolerant Species <br /> � •-�.._... a�• u <br /> stormwater pollutants are all methods utilized by <br /> g <br /> Wet Prairie Plantings <br /> blofiltratlon systems. > I <br /> Vegetated Swales- Vegetative swales possess <br /> less than six percent side slopes and are wide and �� - <br /> shallow to maximize flow residence time and pro- <br /> mote pollutant removal.They are often used down- <br /> stream from detention facilities,around parking lots, _._______..:r•" <br /> In parking lot medians,and along roadsides. ! <br /> Figure VI-4:Vegetated Swale <br /> Vegetated Filter Strips- Filter strips consist of <br /> vegetated sloped strips In which flow Is distributed <br /> broadly along the length of the vegetated area <br /> as overland sheet flow.Requiring ample space to <br /> spread the flow over a wide area at a small depth, ',, --Wet Tolerant Species <br /> suitable areas for filter strips Include shoulders along <br /> uncurbed roads,areas between parking lots and _ /`. / Wet Prairie Plantings <br /> stormwater Inlets, adjacent to vegetated swales <br /> and upstream of Infiltration facilities. " J� 6"-9" Ponding <br /> Media Filters- Media filters strain runoff through 2"-3" Mulch <br /> a medium,such as sand,peat,compost, pellet- <br /> ized leaf compost,Into an underdrain system that~ _... _ .:, <br /> �., . ... , 4'-0" Planting Soil <br /> conveys treated runoff to a detention facility or <br /> the point of ultimate discharge.They can be used —..—._._..._._�..._...._.� 3 ' ; ^r----y-�---_ Filter Fabric <br /> In highly developed sites or be retrofit to existing Is <br /> sites. <br /> _ Optional Sand Layer <br /> Catch Basin Filter Inserts- Catch basin filter <br /> Inserts are suspended within catch basins and Gravel <br /> designed to strain sediment.Since they require high Figure VI-5:Bloretentlon Parking Median Drain <br /> maintenance to avoid hydraulic failure,they are <br /> applicable only to a small drainage area. <br /> -• • P- • • - •rl(". <br /> Stormwater Design Guidelines, <br />