Median pollutant removal percentages for several stormwater BMPs. Sources. More detailed information and ranges of values can be found in other locations in this manual, as indicated in the table.
Link to this table

Practice TSS TP PP DP TN Metals1 Bacteria Hydrocarbons
Infiltration2 3 3 3 3 3 3 3 3
Biofiltration and Tree trench/tree box with underdrain 80 link to table link to table link to table 50 35 95 80
Sand filter 85 50 91 0 35 50 80 80
Iron enhanced sand filter 85 77 91 60 35 50 80 80
Dry swale 68 link to table link to table link to table 35 0 80 80
Wet swale 68 0 0 0 0
Constructed wet ponds4 84 50 91 0 30 70 60 80
Constructed wetlands 73 38 69 0 30 70 60 80
Permeable pavement 74 45 82 0
Green roofs 85 0 0 0

TSS=Total suspended solids, TP=Total phosphorus, PP=Particulate phosphorus, DP=Dissolved phosphorus, TN=Total nitrogen
1Data for metals is based on the average of data for zinc and copper
2BMPs designed to infiltrate stormwater runoff, such as infiltration basin/trench, bioinfiltration, permeable pavement with no underdrain, tree trenches with no underdrain, and BMPs with raised underdrains.
3Pollutant removal is 100 percent for the volume infiltrated, 0 for water bypassing the BMP. For filtered water, see values for other BMPs in the table.
4Dry ponds do not receive credit for volume or pollutant removal

This page was last modified on 6 March 2018, at 08:56.

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