Infiltration BMPs

Infiltration BMPs direct stormwater runoff flows to areas where water can soak or filter through the soil. This BMP type uses natural filtering to remove pollutants from stormwater runoff and reduce stormwater discharges to the storm drain system.

Infiltration devices can be above ground, in the form of trenches or gravel-filled areas, or installed beneath permeable pavement. Typically infiltration devices are dry except in times of heavy rainfall.

Benefits

Infiltration BMP may offer the following benefits:
 

  • Reduced runoff volume and peak flows 
  • Filter pollutants from stormwater runoff

 

What does your Infiltration BMP look like?

Typical Infiltration BMP components can include:
 

  • Inflow distribution mechanisms: Features like flow spreaders or filter strips to evenly spread water as it flows into a treatment area.
  • Energy Dissipation Features: Items like splash blocks or rocks to slow down and reduce the force of runoff.
  • Pretreatment Area: A small pool or area (forebay) that temporarily holds water to trap debris and sediment before it enters the main treatment area. Other methods can be used if they meet specific guidelines.
  • Vegetation: Plants chosen to suit the purpose of the area, local climate, and how much water the area holds.
  • Native Soils: Natural, uncompacted soils at the bottom to absorb water effectively.
  • Overflow Structure: A backup system to safely manage extra water during heavy rains.
     

Target Pollutants

 
  • Sediment (soil particles, road dust, gravel, sand, etc.)
  • Oil and grease
  • Trash
  • Metals
  • Bacteria
     

Inspection & Maintenance Activities

Activity Suggested frequency/schedule
Inspect for accumulation of sediment, litter, or debris Montlhy
Inspect for obstructed inlet or outlet structure Monthly and after significant rain events
Inspect for standing water more than 24-96 hours following a storm event  After significant rain events
Inspect for poor vegetation establishment, dead or diseased vegetation or overgrown vegetation Monthly
Inspect for erosion due to concentrated storm water runoff flow 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