==To calculate the required storage reservoir depth, where the area is fixed or constrained (3D drainage)==
==To calculate the required storage reservoir depth, where the area is fixed or constrained (3D drainage)==
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On densely developed sites the surface area of the facility may be constrained, in this case the required water storage reservoir depth of the bioretention cell or infiltration trench, d, can be calculated assuming three dimensional drainage as follows:
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On densely developed sites the surface area of the facility may be constrained, in this case the required water storage reservoir depth of the bioretention cell or infiltration trench, d, can be calculated assuming three-dimensional drainage as follows:
:<math>d=a[e^{\left ( -bD \right )} -1]</math>
:<math>d=a[e^{\left ( -bD \right )} -1]</math>
Where
Where
Line 79:
Line 79:
<math>b=\frac{xf'}{nAr}</math>
<math>b=\frac{xf'}{nAr}</math>
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(The rearrangement to calculate the required footprint area of the facility for a given depth using three dimensional drainage is not available at this time. Elegant submissions are invited.)<br>
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(The rearrangement to calculate the required footprint area of the facility for a given depth using three-dimensional drainage is not available at this time. Elegant submissions are invited.)<br>