This table shows comparison of phosphorus removal for different BMPs.a,e,f Values represent the percent of incoming pollutant that is removed. Source: MPCA Minnesota Stormwater Manual.
Link to this table
BMP group | BMP design variation | Average TP removal rate (%)b | Maximum TP removal rate (%)c | Average soluble P removal rate (%)d,f,g |
---|---|---|---|---|
Bioretentionf | Underdrain | see Phosphorus credits for bioretention systems with an underdrain | see Phosphorus credits for bioretention systems with an underdrain | see Phosphorus credits for bioretention systems with an underdrain |
Infiltrationh | 100 | 100 | 100 | |
Filtration | Sand filter | 50 | 55 | 0 |
Dry swale | 0 | 35 | 0 | |
Wet swale | 0 | 0 | ||
Infiltrationf | Infiltration trenchh | 100 | 100 | 100 |
Infiltration basinh | 100 | 100 | 100 | |
Stormwater ponds | Wet pond | 50 | 65 | 0 |
Multiple pond | 60 | 75 | 0 | |
Stormwater wetlands | Shallow wetland | 40 | 55 | 0 |
Pond/wetland | 55 | 75 | 0 |
aRemoval rates show in table are a composite of five sources:
b Average removal efficiency expected under MPCA Sizing Rules 1 and 3
c Upper limit on phosphorus removal with increased sizing and design features, based on national review
d Average rate of soluble phosphorus removal in the literature
e See section on calculating credits for each BMP in this Manual.
f Note that the performance numbers apply only to that portion of total flow actually being treated; it does not include any runoff that bypasses the BMP
gNote that soluble P can transfer from surface water to groundwater, but this column refers only to surface water
hNote that 100% is assumed for all infiltration, but only for that portion of the flow fully treated in the infiltration facility; by-passed runoff or runoff diverted via underdrain does not receive this level of treatment.