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→Time for infiltration of surface ponded water
The following equation assumes that infiltration occurs primarily through the footprint of the facility.
The following equation assumes that infiltration occurs primarily through the footprint of the facility.
It is best applied to calculate the maximum duration of ponding on the surface of [[bioretention cells]], [[bioswales]] and [[enhanced grass swales]] to ensure all surface ponding drains within 48 hours.
It is best applied to calculate the maximum duration of ponding on the surface of [[bioretention cells]], [[bioswales]] and [[enhanced grass swales]] to ensure all surface ponding drains within 48 hours.
To calculate the time (''t'') to fully drain the facility through the footprint area only:
To calculate the time (''t'') to fully drain surface ponded water through the filter media or planting soil:
<math>t=\frac{d}{K}</math>
<math>t=\frac{d}{K}</math>
Where d is the mean ponding depth
Where d is the mean ponding depth