This section of the manual is under construction
Physically, each BMP/practice utilizes multiple processes. For example, the practice of a bioinfiltration BMP utilizes the following processes:
- Hydraulic: infiltration, transpiration
- Physical: sedimentation, filtration
- Biological: plant metabolism, nitrification / denitrification, pathogen die-off
- Chemical: adsorption / absorption / ion exchange
- Other: thermal control
The following tables differentiate between stormwater process and practice. Information in the tables has been consolidated in a single table in this Excel file.
- Processes for removing pollutants from stormwater runoff
- Practices for controlling pollutants in stormwater runoff
- Processes utilized by Best Management Practices - Infiltrators
- Processes utilized by Best Management Practices - Swales and Strips
- Processes utilized by Best Management Practices - Filters
- Processes utilized by Best Management Practices - Constructed Basins
- Processes utilized by Best Management Practices - Manufactured Devices
- Processes utilized by Best Management Practices - Storage and Reuse
Summary of attenuation-removal mechanisms for primary pollutants found in stormwater runoff. Adapted from Fundamentals of Urban Runoff Management: Technical and Institutional Issues, 2nd Ed.
Link to this table
| Mechanism | Pollutants affected | Promoted by |
|---|---|---|
| Sedimentation | Solids, BOD, pathogens, particulate COD, P, N, metals, synthetic organics | Low turbulence |
| Filtration | Solids, BOD, pathogens, particulate COD, P, N, metals, synthetic organics | Fine, dense herbaceous plants, constructed filters |
| Soil incorporation | All | Medium-fine texture |
| Precipitation | Dissolved P, metals | High alkalinity |
| Sorption - adsorption | Dissolved P, metals, synthetic organics | High soil Al, Fe, high soil organics (Met), circumneutral pH |
| Sorption - ion exchange | Dissolved metals | High soil cation exchange capacity |
| Oxidation | COD, petroleum hydrocarbons, synthetic organics | Aerobic conditions |
| Degradation - photolysis | COD, petroleum hydrocarbons, synthetic organics | Direct sunlight |
| Degradation - volatilization | Volatile petroleum hydrocarbons, synthetic organics | High temperature and air movement |
| Degradation - biological | BOD, COD, petroleum hydrocarbons, synthetic organics | High temperature and air movement |
| Plant metabolism | P, N, metals | High plant surface area |
| Pathogen die off | Pathogens | Plant excretions |
| Nitrification | Ammonia | Dissolved oxygen >2 mg/L, low toxicants, temperature >5-7°C, circumneutral pH |
| Denitrification | Nitrate, nitrite | Anaerobic, low toxicants, temperature >15°C |
This table shows a list of BMPs and associated pollutant removal mechanisms. Primary (removal) means the BMP was designed for this specific mechanism. Secondary (removal) means the BMP provides additional removal of pollutants for this mechanism even though the BMP was not designed for that purpose. An empty cell means the BMP provides limited or no removal for that mechanism.
| BMP group | Pollutant removal mechanisms | |||||
|---|---|---|---|---|---|---|
| Water quality | ||||||
| Filtration | Infiltration | Settling | Biological uptake | Temperature control | Soil adsorption | |
| Pollution prevention | Not applicable - pollutants not exposed to stormwater | |||||
| Better Site Design/low impact development | primary | secondary | secondary | secondary | secondary | secondary |
| Runoff volume minimization | secondary | secondary | ||||
| Temporary construction sediment control | primary | |||||
| Bioretention | primary | secondary | secondary | secondary | secondary | secondary |
| Filtration | primary | secondary | secondary | secondary | ||
| Infiltration | secondary | primary | secondary | primary | secondary | |
| Stormwater ponds | secondary | primary | secondary | |||
| Stormwater wetlands | secondary | secondary | primary | primary | secondary | |
| Supplemental treatment | Each supplemental and proprietary device should be carefully studied to learn the primary and secondary removal functions | |||||