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|
|Stormwater ponds||Wet pond||50||75||0|
|Stormwater wetlands||Shallow wetland||40||55||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.