In
Brief:
| Bioretention is a low impact development (LID) type of BMP that uses a combination of physical and chemical processes to improve runoff quality and reduce runoff quantity and peak flow rates. Bioretention generally consists of a porous media layer base with a vegetative layer above and a surface of mulch. These layers serve to remove pollutants through processes that include infiltration, filtration, adsorption and transformation.
A bioretention cell was constructed in a parking lot adjacent to the Hal Marshall Municipal Services Building in Charlotte, North Carolina. The cell was designed according to the NC Division of Water Quality Stormwater BMP Design Manual. The surface area was 2,480ft2 and the above ground storage volume was 1,460 ft2. The soil media was 4’ of loamy sand with a low P index and a silt/clay fraction of 5.78%. There was a 6” corrugated plastic pipe that served as the underdrain system which discharged into a weir box with baffle and 30deg v-notch weir. The cell also had a layer of mulch and was planted with vegetation at a density of 2,800 stems/ac.
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