Post-construction stormwater Best Management Practices Post-construction stormwater Best Management Practices

Post-construction Best Management Practices (BMPs) are the BMPs that exist following construction of new development or re-development. Post-construction BMPs are typically permanent structural BMPs but include other BMPs such as pollution prevention, street sweeping, and pretreatment practices.

NOTE: Not all the practices indicated below can be used to meet the Construction Stormwater General Permit. The permit states "Where a project’s ultimate development replaces vegetation and/or other pervious surfaces with one (1) or more acres of cumulative impervious surface, the Permittee(s) must design the project so that the water quality volume of one (1) inch of runoff from the new impervious surfaces created by the project is retained on site (i.e. infiltration or other volume reduction practices) and not discharged to a surface water". To meet this requirement, post-construction practices include permanent treatment with infiltration/filtration BMPs, wet sedimentation basins, and/or regional ponds.

This page is organized into pretreatment practices (which are required for many structural BMPs), permanent practices as discussed in the Construction Stormwater Permit, and other practices (which do not qualify for meeting requirements of the construction permit).

Permanent practices

1. Infiltration practices
   1. Bioinfiltration/bioretention with no underdrain (rain garden)
   2. Infiltration - includes the following practices: infiltration trench, dry wells, infiltration basin, underground infiltration
   3. Permeable pavement with no underdrain
   4. Tree trench/tree box with no underdrain
   5. Dry swale (Grass swale)
   6. High-gradient stormwater step-pool swale
   7. Stormwater re-use and rainwater harvesting - captured water routed to one of the above BMPs
2. Filtration practices - these practices typically achieve little or no infiltration but can be designed to provide some infiltration. Examples include BMPs with a raised underdrain and swales with check dams or a bioretention base.
   1. Biofiltration/bioretention with an underdrain
   2. Permeable pavement with an underdrain
   3. Tree trench/tree box with an underdrain
   4. Dry swale (Grass swale)
   5. Wet swale (wetland channel)
   6. High-gradient stormwater step-pool swale
   7. Sand filters
   8. Iron enhanced sand filter (Minnesota Filter)
   9. Green roofs
   10. Stormwater re-use and rainwater harvesting - captured water routed to a filtration BMP
3. Wet sedimentation basin and regional ponds
   1. Stormwater ponds
   2. Stormwater wetlands

Other practices

1. Pollution prevention
   1. Better site design
   2. Hydrodynamic devices (also see Pretreatment
   3. Filtration devices (also see Pretreatment
   4. Street sweeping
   5. Education
   6. Road de-icing
   7. Yard waste management