Median pollutant removal of total nitrogen by stormwater treatment practices. Values represent percentage of incoming pollutant load that is removed. Source: Minnesota Stormwater Manual. Manual data was based on information from ASCE/EPA International Database; Winer (2000)
BMP group Total nitrogen
Bioretentiona 45
Filtrationb 35
Infiltrationc 100
Stormwater ponds 30
Stormwater wetlands 30

aData based on fewer than five monitoring studies
bExcludes vertical sand filters and filter strips
cNote that 100% is assumed for all infiltration, but only for that portion of the flow fully treated in the infiltration facility; by-passed runoff does not receive any treatment.

This page was last edited on 3 January 2013, at 22:06.