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Infiltration: Sizing and modeling (view source)
Revision as of 03:34, 18 November 2019
, 4 years agono edit summary
__NOTOC__
__NOTOC__
<imagemap>
Image:Infiltration.png|thumb|700 px|This is an image map; clicking on components will load the appropriate article.
poly 315 507 208 555 317 605 423 555 [[Drainage time]]
rect 210 658 426 730 [[Details]]
rect 568 522 728 594 [[Underdrain]]
poly 73 27 39 75 75 126 179 126 215 78 181 27 [[Infiltration]]
poly 268 25 235 75 270 123 364 124 395 76 365 25 [[Infiltration: Testing]]
rect 237 185 397 225 [[Select BMP type]]
rect 238 266 397 329 [[Bioretention: Sizing]]
</imagemap>
{{textbox|
{{textbox|
{{plainlist|
{{plainlist|
#The minimum total depth may be limited by the need to support vegetation i.e. not < 0.6 m.
#The minimum total depth may be limited by the need to support vegetation i.e. not < 0.6 m.
#[[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 close to 1.
#[[Infiltration trenches]], [[Infiltration chambers| chambers]] and [[bioretention cells]] 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.
{|class="wikitable"
{|class="wikitable"
!style="background: darkcyan; color: white"|Parameter
!style="background: darkcyan; color: white"|Parameter
|-
|-
|''D''||hrs||Duration of design storm (for MOECC volume based caclulations set to 1)
|''D''||hrs||Duration of design storm (for MOECC volume based calculations set to 1)
|-
|-
|''i''||mm/hr||Intensity of design storm (for MOECC volume based calculations use whole storm depth (link to map))
|''i''||mm/hr||Intensity of design storm (for MOECC volume based calculations use whole storm depth (link to map))
and
and
<math>b=\frac{xq}{nP}</math>
<math>b=\frac{xq}{nP}</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.)
==To calculate the required depth, where the area of the facility is constrained (1D)==
==To calculate the required depth, where the area of the facility 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+qD}</math>
<math>P=\frac{IiD}{nd+qD}</math>
==Time for infiltration of surface ponded water==
==Time for infiltration of surface ponded water==
It is best applied to calculate the limited duration ponding on the surface of [[bioretention cells]], [[bioswales]] and [[enhanced grass swales]].
It is best applied to calculate the limited duration ponding on the surface of [[bioretention cells]], [[bioswales]] and [[enhanced grass swales]].
To calculate the time (''t'') to fully drain the facility through the footprint area only:
To calculate the time (''t'') to fully drain the facility through the footprint area only:
<math>t=\frac{nd}{K}</math>
<math>t=\frac{d}{K}</math>
==Drawdown time to empty facility==
==Drawdown time to empty facility==
[[file:Hydraulic radius.png|thumb|Three footprint areas of 9 m<sup>2</sup>.<br>
[[file:Hydraulic radius.png|thumb|Three footprint areas of 9 m<sup>2</sup>.<br>
From left to right x = 12 m, x = 14 m, and x = 16 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 between 48-72 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.