Changes

|Filter media Plant-Available Phosphorus > 40 ppm||Filter media Plant-Available Phosphorus < 40 ppm

|Filter media Plant-Available Phosphorus > 40 ppm||Filter media Plant-Available Phosphorus < 40 ppm

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|Filter media predominantly sand||Filter media contains fractions of fines and organic material in sand

|Filter media is predominantly sand||Filter media is a mixture of sand, topsoil and organic material

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|Surface covered with stone (or uncovered)||Surface covered with mulch and dense vegetation

|Surface covered with turf grass and stone||Surface covered with mulch and dense, deeply rooting vegetation

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===Sizing and Modelling===

===Sizing and Modelling===

Bioretention facilities should be sized to accommodate runoff from approximately 10 to 20 times the footprint area of the facility. i.e. they should have an I/P ratio of 10 to 20.  

Bioretention facilities should be sized to accommodate runoff from approximately 5 to 20 times the footprint area of the facility. i.e. they should have an I/P ratio of 5 to 20.  

When the drainage area is too large, silt can accumulate very rapidly, overwhelm the [[pretreatment]] devices, and lead to clogging of the facility.  

When the drainage area is too large, silt can accumulate very rapidly, overwhelm the [[pretreatment]] devices, and lead to clogging of the facility.  

When the drainage area is relatively small compared to a bioretention facility, it can make the facility appear unreasonably costly.   

When the drainage area is relatively small compared to a bioretention facility, it can make the facility unreasonably costly.   

*'''[[Bioretention: Sizing| Sizing]]'''

*'''[[Bioretention: Sizing| Sizing]]'''

*'''[[Bioretention: TTT| Modelling]]'''

*'''[[Bioretention: TTT| Modelling]]'''

*A [[gravel diaphragm]] for sheet flow

*A [[gravel diaphragm]] for sheet flow

*[[Vegetated filter strips]] for sheet flow

*[[Vegetated filter strips]] for sheet flow

*A [[Forebays|forebay]] for concentrated overground flow

*A [[Forebays|forebay]] for concentrated surface flow

*An [[Oil and grit separators|oil and grit separator]] for concentrated underground flow

*An [[Oil and grit separators|oil and grit separator]] for concentrated underground flow