BMP pollutant removal for phosphorus | Minnesota Stormwater Manual

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.

**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.**
BMP group	BMP design variation	Average TP removal rate (%)^b	Maximum TP removal rate (%)^c	Average soluble P removal rate (%)^d,f,g
Bioretention^f	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
Bioretention^f	Infiltration^h	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion
Filtration	Sand filter	50	55	0
	Dry swale	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
	Wet swale	0	35	0
Infiltration^f	Infiltration trench^h	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion
Infiltration^f	Infiltration basin^h	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion	100 for infiltrated portion 0 for non-infiltrated portion
Stormwater ponds	Wet pond	46	75	0
Stormwater ponds	Multiple pond	60	75	0
Stormwater wetlands	Shallow wetland	38	55	0
Stormwater wetlands	Pond/wetland			0
^aRemoval rates show in table are a composite of five sources: -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.