Changes

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[[File:Bioretention_TSS.png|200px|thumb]]

[[File:Bioretention_TSS.png|200px|thumb]]

The two box plot figures to the right show combined stormwater effluent quality results from STEP monitoring projects conducted over a 16-year time period (between 2005 and 2021) at sites within Greater Toronto Area (GTA) municipalities.  Total Suspended Solid (TSS) effluent concentration results for bioretention practices represent the combined results from 9 sites in the GTA and a total of 301 monitored storm events.  Median TSS concentration was found to be 9.5 mg/L and exceeded the Canadian Water Quality Guideline of 30 mg/L (CCME, 2002<ref>Canadian Council of Ministers of the Environment (CCME). 2002. Canadian water quality guidelines for the protection of aquatic life: Total particulate matter. In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment, Winnipeg</ref>) during only 15% of the 301 monitored storm events.  In comparison, median TSS effluent concentration for bioretention in the International Stormwater BMP Database was found to be 10.0 mg/L, based on 685 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, so quite similar to results from STEP studies. Median TP concentration was found to be 0.09 mg/L and exceeded the Ontario Provincial Water Quality Objective (PWQO) of 0.03 mg/L (OMOEE, 1994<ref>Ontario Ministry of Environment and Energy (OMOEE), 1994. Policies, Guidelines and Provincial Water Quality Objectives of the Ministry of Environment and Energy. Queen’s Printer for Ontario. Toronto, ON.</ref>) during 86% of monitored storm events.  In comparison, median TP effluent concentration for bioretention in the International Stormwater BMP Database was found to be 0.240 mg/L, based on 667 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, which is well above the Ontario PWQO of 0.03 mg/L. These results indicate that the design of bioretention draining to phosphorus-limited receiving waterbodies should include variations to improve [[Phosphorus]] retention.  An example of such a design variation is including sorption [[Additives| additives]] in [[Bioretention: Filter media]].  Please refer to the [[Phosphorus]] and [[Additives]] pages for further guidance.

The two box plot figures to the right show combined stormwater effluent quality results from STEP monitoring projects conducted over a 16-year time period (between 2005 and 2021) at sites within Greater Toronto Area (GTA) municipalities.  Total Suspended Solid (TSS) effluent concentration results for bioretention practices represent the combined results from 9 sites in the GTA and a total of 301 monitored storm events.  Median TSS concentration was found to be 9.5 mg/L and exceeded the Canadian Water Quality Guideline of 30 mg/L (CCME, 2002<ref>Canadian Council of Ministers of the Environment (CCME). 2002. Canadian water quality guidelines for the protection of aquatic life: Total particulate matter. In: Canadian Environmental Quality Guidelines, Canadian Council of Ministers of the Environment, Winnipeg</ref>) during only 15% of the 301 monitored storm events, similar to STEP [[Permeable pavements#Water_Quality| Permeable Pavements performance]] results.  In comparison, median TSS effluent concentration for bioretention in the International Stormwater BMP Database was found to be 10.0 mg/L, based on 685 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, so quite similar to results from STEP studies. Median TP concentration was found to be 0.09 mg/L and exceeded the Ontario Provincial Water Quality Objective (PWQO) of 0.03 mg/L (OMOEE, 1994<ref>Ontario Ministry of Environment and Energy (OMOEE), 1994. Policies, Guidelines and Provincial Water Quality Objectives of the Ministry of Environment and Energy. Queen’s Printer for Ontario. Toronto, ON.</ref>) during 86% of monitored storm events.  In comparison, median TP effluent concentration for bioretention in the International Stormwater BMP Database was found to be 0.240 mg/L, based on 667 monitored storm events (Clary et al. 2020)<ref>Clary, J., Jones, J., Leisenring, M., Hobson, P., Strecker, E. 2020. International Stormwater BMP Database: 2020 Summary Statistics. The Water Research Foundation. [https://www.waterrf.org/system/files/resource/2020-11/DRPT-4968_0.pdf</ref>, which is well above the Ontario PWQO of 0.03 mg/L. These results indicate that the design of bioretention draining to phosphorus-limited receiving waterbodies should include variations to improve [[Phosphorus]] retention.  An example of such a design variation is including sorption [[Additives| additives]] in [[Bioretention: Filter media]].  Please refer to the [[Phosphorus]] and [[Additives]] pages for further guidance.

[[File:Bioretention_TP.png|200px|thumb]]

[[File:Bioretention_TP.png|200px|thumb]]

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