Detention BMPs

Detention BMPs help prevent flooding by temporarily holding stormwater runoff on your property before it drains into the local storm drain system.

As water ponds in the detention basin, pollutants settle on the basin floor, and remaining water is slowly released into the storm drain system.

 

Benefits

Detention BMPs may offer the following benefits:

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

 

What does your Detention BMP look like?

Typical Detention BMP components can include:
 

  • Forebay for pretreatment
  • Basin for temporarily storing storm water runoff
  • Vegetation (selected based on basin use, climate, and ponding depth)
  • Low-flow outlet structure and overflow device
     

Target Pollutants

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

Inspection & Maintenance Activities

Activity Suggested frequency/schedule
Inspect for accumulation of sediment, litter, and debris Monthly
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 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