Changes

===Filter Bed Surface Infiltration Rate===

===Filter Bed Surface Infiltration Rate===

To evaluate surface infiltration rate using a surface ponding well during a simulated storm event, the filter media bed should be thoroughly wetted prior to the test. Measurements of filter bed drainage rate and corresponding estimates of surface infiltration rate should be made following natural or simulated storm events that deliver enough water to the BMP to pond at least 75 mm of water on the surface of the filter media bed, in an effort to consistently approximate saturated soil flow conditions.  

To evaluate surface infiltration rate using a surface ponding well during a natural or simulated storm event, the filter media bed should be thoroughly wetted prior to the test. Measurements of filter bed drainage rate and corresponding estimates of surface infiltration rate should be made following natural or simulated storm events that deliver enough water to the BMP to pond at least 75 mm of water on the surface of the filter media bed, in an effort to consistently approximate saturated soil flow conditions.  

====Calculation====

====Calculation====

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|[[Filter media|Filter bed surface]]

|[[Filter media|Filter bed surface]]

|Use an infiltrometer or permeameter to measure field saturated hydraulic conductivity (K_S) in at least 3 locations for areas up to 2,500 m² and one additional location for each additional 1,000 m² of filter bed surface area, including inlet and lowest elevation areas. Compare mean and individual values to the design specification or trigger value (See Triggers for follow-up and corrective actions below) to determine if follow-up tasks are needed.

|Use an infiltrometer or permeameter to measure field saturated hydraulic conductivity (K_S) in at least 3 locations for areas up to 500 m² and one additional location for each additional 500 m² of filter bed surface area, or fraction thereof, including inlet and lowest elevation areas. Compare mean and individual values to the design specification or trigger value (See Triggers for follow-up and corrective actions below) to determine if follow-up tasks are needed.)

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|rowspan="2"|'''[[Permeable pavement]]'''

|rowspan="2"|'''[[Permeable pavement]]'''

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|[[Permeable pavement: Plan review|Pavement surface]]

|[[Permeable pavement: Plan review|Pavement surface]]

|Use a single-ring infiltrometer to measure field saturated hydraulic conductivity (K_S) in at least 3 locations for areas up to 2,500 m² and one additional location for each additional 1,000 m² of pavement surface area, evenly distributed. For permeable interlocking pavers, follow the procedure provided by ASTM C1781_C1781M – 15 (ASTM International, 2015<ref>ASTM International. 2015. ASTM C1781/C1781M-15 - Standard Test Method For Surface Infiltration Rate Of Permeable Unit Pavement Systems. Accessed May 5 2022: https://webstore.ansi.org/Standards/ASTM/astmc1781c1781m15</ref>). For pervious concrete or porous asphalt, follow the procedure provided by ASTM C1701_C1701M – 09 (ASTM International, 2009<ref>ASTM International. 2009. ASTM C1701/C1701M-09 - Standard Test Method for Infiltration Rate of In Place Pervious Concrete. Accessed May 5 2022: https://www.astm.org/c1701_c1701m-09.html</ref>). Compare mean and individual values to the design specification or trigger value (See Triggers for follow-up and corrective actions below) to determine if follow-up tasks are needed.   

|Use a single-ring infiltrometer to measure field saturated hydraulic conductivity (K_S) in at least 3 locations for areas up to 2,500 m² and one additional location for each additional 1,000 m² of pavement surface area, or fraction thereof, evenly distributed. For permeable interlocking pavers, follow the procedure provided by ASTM C1781_C1781M – 15 (ASTM International, 2015<ref>ASTM International. 2015. ASTM C1781/C1781M-15 - Standard Test Method For Surface Infiltration Rate Of Permeable Unit Pavement Systems. Accessed May 5 2022: https://webstore.ansi.org/Standards/ASTM/astmc1781c1781m15</ref>). For pervious concrete or porous asphalt, follow the procedure provided by ASTM C1701_C1701M – 09 (ASTM International, 2009<ref>ASTM International. 2009. ASTM C1701/C1701M-09 - Standard Test Method for Infiltration Rate of In Place Pervious Concrete. Accessed May 5 2022: https://www.astm.org/c1701_c1701m-09.html</ref>). Compare mean and individual values to the design specification or trigger value (See Triggers for follow-up and corrective actions below) to determine if follow-up tasks are needed.)  

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At a minimum, continuous monitoring should be undertaken as part of Assumption and Verification inspections in the following situations:  

At a minimum, continuous monitoring should be undertaken as part of Assumption and Verification inspections in the following situations:  

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#When little information is available about the effectiveness of a certain type of BMP or treatment train (i.e., combination of BMPs) or when a new technology is being implemented for the first time in a certain context.

#Where the sensitivity of the receiving water warrants a high level of inspection and testing to determine if BMP effluent quality meets design specifications or regulatory criteria.

#As part of Forensic inspection and Testing (FIT) work to determine corrective actions for suspected problems with drainage or effluent quality detected through other inspection and testing work.}}

#When little information is available about the effectiveness of a certain type of BMP in a certain environmental context, or when a new technology is being implemented for the first time in a certain context or geographic region.

#Where the sensitivity of the receiving water warrants a high level of inspection and testing to determine if BMP effluent quality meets design specifications or regulatory criteria.}}

===External guidance on monitoring the performance of stormwater BMPs===

===External guidance on monitoring the performance of stormwater BMPs===