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| ==Calculate drawdown time== | | ==Calculate drawdown time== |
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| [[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 = 14 m, and x = 16 m]] |
− | The 3 dimensional equations make use of the hydraulic radius (''P''/''x''), where ''x'' is the perimeter (m) of the facility. <br>
| + | To calculate the time (''t'') to fully drain the facility: |
− | Maximizing the perimeter of the facility directs designers towards longer, linear shapes such as [[infiltration trenches]] and [[bioswales]].
| + | :<math>t=\frac{V_{R}A_{p}} {q'P}ln\left [ \frac{\left (d+ \frac{A_{p}}{P} \right )}{\left(\frac{A_{p}}{P}\right)}\right]</math> |
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− | To calculate the required depth:
| + | This 3 dimensional equation makes use of the hydraulic radius (''A<sub>p</sub>''/''P''), where ''P'' is the perimeter (m) of the facility. <br> |
− | :<math>d=a[e^{\left ( -bD \right )} -1]</math>
| + | Maximizing the perimeter of the facility directs designers towards longer, linear shapes such as [[bioswales]]. |
− | Where
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− | <math>a=\frac{A_{p}}{x}-\frac{i I}{A_{p}q'}</math>
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− | and
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− | <math>b=\frac{xq}{nP}</math>
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− | The rearrangement to calculate the required footprint area of the facility for a given depth is not available at this time. Elegant submissions are invited.
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− | To calculate the time (''t'') to fully drain the facility:
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− | <math>t=\frac{V_{R}A_{p}} {q'P}ln\left [ \frac{\left (d+ \frac{A_{p}}{P} \right )}{\left(\frac{A_{p}}{P}\right)}\right]</math>
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| [[category: modeling]] | | [[category: modeling]] |
| [[category: infiltration]] | | [[category: infiltration]] |