Information: The values in this table represent information from the literature. The values do not represent credits provided elsewhere in this manual. See, for example, Information on pollutant removal by BMPs and Phosphorus credits for bioretention systems with an underdrain
| BMP Group | BMP Design Variation | Average TP Removal Rate (%)b | Maximum TP Removal Rate (%)c | Average Soluble P Removal Rate (%)dg |
|---|---|---|---|---|
| Bioretention | Underdrain | 59 see Phosphorus credits for bioretention systems with an underdrain |
80 see Phosphorus credits for bioretention systems with an underdrain |
0 see Phosphorus credits for bioretention systems with an underdrain |
| Infiltration |
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| Filtration | Media Filter | 50 | 55 | 0 |
| Vegetative Filters (dry) | 50 | 55 | 0 | |
| Wet Swale | 0 | 35 | 0 | |
| Infiltrationf,i | Infiltration Trench |
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| Infiltration Basin |
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| Stormwater Ponds | Wet Pond | 50 | 75 | 0 |
| Multiple Pond | 60 | 75 | 0 | |
| Stormwater Wetlands | Shallow Wetland | 40 | 45 | 0 |
| Pond/Wetland | 44 | 49 | 33 | |
| a Removal rates shown in table are a composite of five sources: ASCE/EPA International BMP Database; Caraco (CWP), 2001; MDE, 2000; Winer (CWP), 2000; and Issue Paper D P8 modeling b Average removal efficiency expected under MPCA Construction Stormwater General Permit sizing requirements c Upper limit on phosphorus removal with increased sizing and design features, based on national review d Average rate of soluble phosphorus removal in literature e See also Stormwater pollutant removal, stormwater credits f Note that the performance numbers apply only to that portion of total flow actually being treated; it does not include any runoff that by-passes the BMP g Note that soluble P can transfer from surface water to ground water, but this column refers only to surface water h Note 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 |
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Caution: 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.