Biofiltration BMPs

Biofiltration BMPs remove pollutants found in stormwater runoff, while also addressing potential changes in the flow of runoff caused by development. These facilities mimic natural processes, relying on vegetation, soil, and other components to filter pollutants from stormwater.

 


Benefits

Biofiltration BMPs may offer the following benefits:

  • Reduce runoff volume and peak flows when infiltration is possible
  • Decrease downstream erosion
  • Filter pollutants from stormwater, improving water quality
  • Contribute to local habitat creation and boost biodiversity
  • Can offer aesthetic value
  • Promote evapotranspiration, helping manage excess water naturally

 

What does your BMP look like?

Typical biofiltration BMPs components can include:
 

  1. Inflow distribution systems to manage water entry
  2. Energy dissipation features which reduce erosion caused by concentrated inflows
  3. Shallow surface ponding areas for capturing flows
  4. Climate and ponding depth-appropriate vegetation for side slopes and basin bottoms
  5. Non-floating mulch layer for stability and moisture retention
  6. Media layer to support vegetation growth and filtration of runoff
  7. Filter layer with aggregate (small stones or gravel) to prevent fine particles from migrating into native soils or the aggregate storage layer
  8. Aggregate storage layer with underdrains
  9. Impermeable liner (usually made of plastic or rubber) or uncompacted native soils at the facility's base
  10. Overflow structure for excess water management
     

Target Pollutants

 
  • Sediment (soils particles, road dust, gravel, sand, etc.)
  • Fertilizers
  • Pesticides
  • Trash
     

Inspection & Maintenance Activities

Activity Suggested frequency/schedule
Inspect for accumulation of sediment, litter, or debris Montlhy
Inspect for damage to structural components such as weirs, inlet or outlet structures Monthly and after significant rain events           
Inspect for poor vegetation establishment, dead or diseased vegetation or overgrown vegetation Monthly
Inspect for proper drainage and erosion After significant rain events
Check for signs of mosquito breeding Monthly and after significant rain events


BMP Fact Sheets in PDF format

Structural BMP Outreach Flyers (Educational Resources Page)
 

Contact

  (858) 495-5323

  BMP.Program@sdcounty.ca.gov

 

 

Maintaining My Structural BMP Home Page