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

BMP Design Design recommendations
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.

This page was last edited on 25 February 2020, at 22:21.