Changes

#The ''maximum'' total depth will be limited by construction practices i.e. usually ≤ 2 m.

#The ''maximum'' total depth will be limited by construction practices i.e. usually ≤ 2 m.

#The ''maximum'' total depth may be limited by the [[Infiltration| conditions underground]] e.g. the groundwater or underlying geology/infrastructure.

#The ''maximum'' total depth may be limited by the [[Infiltration| conditions underground]] e.g. the groundwater or underlying geology/infrastructure.

#The minimum total depth may be limited by the need to support vegetation i.e. not < 0.6 m.

#The ''maximum'' total depth may be limited by the need to support vegetation on top of it (e.g. at least 30 cm of planting soil fill above the BMP to support grasses)

#[[Green roofs]], [[absorbent landscapes]] and [[permeable paving]] often receive very little flow from other surfaces, so that the I/P ratio is close to 1.

#[[Green roofs]], [[absorbent landscapes]] and [[permeable paving]] often receive very little flow from other surfaces, so that the I/P ratio is typically between 0 and 2.

#[[Infiltration trenches]], [[Infiltration chambers| chambers]] and [[bioretention]] have a maximum recommended I/P ratio of 20.

#[[Infiltration trenches]], [[Infiltration chambers| chambers]] and [[bioretention]] have a maximum recommended I/P ratio of 20.

|''d''||m||Depth of the infiltration BMP, total of all components

|''d''||m||Depth of the infiltration BMP, total of all components

|-

|-

|''P''||m²||Permeable area i.e. footprint area of the infiltration BMP

|''Ap''||m²||Permeable area i.e. footprint area of the infiltration BMP

|-

|-

|''K''||mm/hr||Saturated hydraulic conductivity of the filter media or fill used in the infiltration BMP   

|''K''||mm/hr||Saturated hydraulic conductivity of the filter media or fill used in the infiltration BMP   

:<math>d=a[e^{\left ( -bD \right )} -1]</math>

:<math>d=a[e^{\left ( -bD \right )} -1]</math>

Where

Where

<math>a=\frac{P}{x}-\frac{i I}{P f'}</math>

<math>a=\frac{Ap}{x}-\frac{i I}{Ap f'}</math>

and  

and  

<math>b=\frac{xf'}{nP}</math>

<math>b=\frac{xf'}{nAp}</math>

(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensions of underground infiltration is not available at this time. Elegant submissions are invited.)

(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensions of underground infiltration is not available at this time. Elegant submissions are invited.)

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.

In some very constrained sites, the surface area of the BMP may be limited, in this case the required depth of cell or trench can be calculated.

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

Note that in most cases the results of this calculation will be very similar to those of the above equation using 3D infiltration.  

:<math>d=\frac{D\left[\left( \frac{I}{P} \right )i-f' \right]}{n}</math>

:<math>d=\frac{D\left[\left( \frac{I}{Ap} \right )i-f' \right]}{n}</math>

==To calculate the require facility area or footprint where the depth is constrained (1D)==

==To calculate the require facility area or footprint where the depth is constrained (1D)==

In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In this case the required storage needs to be distributed more widely across the landscape. The overall are of BMP required can be calculated:

In many locations throughout Ontario, there may be limited depth of soil available into which stormwater may be infiltrated. In this case the required storage needs to be distributed more widely across the landscape. The overall are of BMP required can be calculated:

<math>P=\frac{IiD}{nd+f'D}</math>

<math>Ap=\frac{IiD}{nd+f'D}</math>

==Time for infiltration of surface ponded water==

==Time for infiltration of surface ponded water==

[[file:Hydraulic radius.png|thumb|Three footprint areas of 9 m².<br>

[[file:Hydraulic radius.png|thumb|Three footprint areas of 9 m².<br>

From left to right x = 12 m, x = 20 m]]

From left to right x = 12 m, x = 20 m]]

The target [[drawdown time]] for the internal storage of an infiltration facility is between 48-72 hours. <br>

The target [[drawdown time]] for the internal storage of an infiltration facility is typically between 48 and 72 hours. <br>

For some geometries (e.g. particularly deep facilities or linear facilities), it preferable to account for lateral infiltration.  

For some geometries (e.g. particularly deep facilities or linear facilities), it preferable to account for lateral infiltration.  

The 3D equation make use of the hydraulic radius (''P''/''x''), where ''x'' is the perimeter (m) of the facility. <br>

The 3D equation make use of the hydraulic radius (''Ap''/''x''), where ''x'' is the perimeter (m) of the facility. <br>

'''Maximizing the perimeter of the facility directs designers towards longer, linear shapes such as [[infiltration trenches]] and [[bioswales]].'''   

'''Maximizing the perimeter of the facility directs designers towards longer, linear shapes such as [[infiltration trenches]] and [[bioswales]].'''   

To calculate the time (''t'') to fully drain the facility:  

To calculate the time (''t'') to fully drain the facility:  

<math>t=\frac{nP}{f'x}ln\left [ \frac{\left (d+ \frac{P}{x} \right )}{\left(\frac{P}{x}\right)}\right]</math>

<math>t=\frac{nAp}{f'x}ln\left [ \frac{\left (d+ \frac{Ap}{x} \right )}{\left(\frac{Ap}{x}\right)}\right]</math>

[[category: modeling]]

[[category: modeling]]

[[category: infiltration]]

[[category: infiltration]]