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[[Category:Level 2 - Pollutants/Phosphorus]]
 
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Revision as of 11:58, 7 August 2022

Summary of stormwater design recommendations to enhance phosphorus removal.
Link to this table

BMP Design Design recommendations
Infiltration
Filtration (includes practices with an underdrain)
  • Organic filters are a source of soluble phosphorus and should not be used
  • Practices with engineered media are acceptable when the appropriate filter media is used
  • Employ finer-grained media in the filter bed with a small diameter (15 microns), or provide a finer-grained layer at mid-depth in the filter profile
  • The process for pretreatment and/or filtration should extend from 36 to 48 hours, where possible
  • Filters should be oriented to provide maximum solar exposure
  • Wet swales are not recommended because they may export phosphorus
  • Open channels should be designed to promote maximum sediment retention
Stormwater ponds1
  • Pond aeration is encouraged
  • Design wet ponds with a depth no greater than 10 feet to prevent stratification and potential release of phosphorus from bottom sediments
  • Avoid the use of dry or dry extended detention ponds
  • Designers should consider the snowmelt runoff volume and design ponds for seasonal operation
  • Use a surface or mid-depth release from the pond
  • Landscape pond to discourage geese
  • Add shallow benches and wetland areas to enhance the plankton community
  • Pond sediments may be amended to retain phosphorus (e.g. iron, aluminum)
Constructed Stormwater wetlands
  • Pond/ wetland system is the preferred wetland design
  • Use a surface or mid-depth release from the wetland
  • Maximize surface micro-topography
  • Landscape wetland to discourage geese

1The recommendations for constructed ponds are from the original Minnesota Stormwater Manual. MPCA anticipates updating this information in the near future.