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2 AC Max: 1 AC " <br />Drainage Area For Filtration <br />Max Impervious <br />Design (Per Puictiae) <br />2ACMax..112AC <br />Drainage Area l -or Infiltration <br />Max Imlrerv10r+s <br />Design (Per-r@ctice) <br />20T: <br />Max. Slope of Site <br />�. <br />Min. Depth to Bedrock & Se�i - <br />sonally Hig'� \A/ater Table <br />NRCS Soil Type <br />A,B -Normal <br />•Lan be used in CSD soil lypes ;.,d. n)oilikalions <br />Good <br />Freeze/ Thaw Suitability <br />Suitable <br />Potential Hotspot Runoff <br />- <br />'I quire: imp Limeable , or <br />Description: <br />In general, bioretention systems can be described <br />as shallow, landscaped depressions commonly <br />located in parking lot islands or within small pockets <br />in residential areas that receive stormwater runoff <br />(Metropolitan Council Small Sites BMP Manual, <br />2001). <br />Bioretention facilities capture rainwater runoff to <br />be filtered through a prepared soil medium. Once <br />the soil pore space capacity of the medium is <br />exceeded, stormwater begins to pool at the surface <br />of the planting soil. Pollutants are removed by a <br />number of processes including adsorption, filtration, <br />volatilization, ion exchange and decomposition <br />(Prince George's County, MD, 1993). Filtered <br />runoff can either be allowed to infiltrate into the <br />surrounding soil (functioning as an infiltration basin <br />or rainwater garden), or collected by an under -drain <br />system and discharged to the storm sewer system <br />or directly to receiving waters (functioning like a <br />surface sand filter). Runoff from larger storms is <br />generally diverted past the area to the storm drain <br />system (Metropolitan Council Small Sites BMP <br />Manual, 2001). <br />Bioretention is a stormwater treatment practice <br />that utilizes the chemical, biological and physical <br />properties of plants, microbes and soils for capturing/ <br />reducing stormwater runoff and removing pollutants <br />from runoff. This process is often incorporated into <br />many different types of filtration and infiltration <br />stormwater treatment practices. <br />STORM SEQUENCE <br />Start of Storm Event - Initial runoff & storacle <br />uuration of storm tvent- titorage w mirationnntutranon <br />Following Storm Event- Remaining storage draw -down <br />''roti r, <br />Graphics Courtesv of Rice Creek Watershed District <br />