BMP pollutant removal for phosphorus

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

Information: Removal rates shown here are composite averages intended solely for use in comparing performance between BMP designs and for use in calculating load reduction in site-based TP models. They have been adapted, rounded and slightly discounted from statistical values published in BMP performance databases.

BMP group	BMP design variation	Average TP removal rateb	Maximum TP removal ratec	Average soluble P removal rated,g
Bioretention	Underdrain	65	75	60
	Infiltration	100	100	100
Filtration	Sand filter	50	55	0
	Dry swale	0	55	0
	Wet swale	65	75	70
Infiltrationf	Infiltration trench	100	100	100
	Infiltration basin	100	100	100
Stormwater ponds	Wet pond	50	65	70
	Multiple pond	60	75	75
Stormwater wetlands	Shallow wetland	40	55	50
	Pond/wetland	55	75	65

^a Removal rates show in table are a composite of five sources: [(http://www.bmpdatabase.org ASCE/EPA International Database]; Caraco (Center for Watershed protection, 2001); Maryland Department of the Environment(2000); Winer (Center for Watershed Protection, 2000); P8 modeling (William Walker)
^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.