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The following calculation is used to size the stone storage bed (reservoir) used as a base course. It is assumed that the footprint of the stone bed will be equal to the footprint of the pavement. The following equations are derived from the ICPI Manual <ref>Smith, D. 2006. Permeable Interlocking Concrete Pavements; Selection, Design, Construction, Maintenance. 3rd Edition. Interlocking Concrete Pavement Institute. Burlington, ON.</ref>
The following calculation is used to size the stone storage bed (reservoir) used as a base course. It is assumed that the footprint of the stone bed will be equal to the footprint of the pavement. The following equations are derived from the ICPI Manual <ref>Smith, D. 2006. Permeable Interlocking Concrete Pavements; Selection, Design, Construction, Maintenance. 3rd Edition. Interlocking Concrete Pavement Institute. Burlington, ON.</ref>
===To calculate the total depth of the foundations (all aggregate layers)===
===To calculate the maximum total depth of all aggregate layers needed for pavement support and reservoir storage===
The equation for the depth of the stone foundation (''d<sub>f, max</sub>'', mm) is as follows:
The equation for the depth of the stone reservoir (''d<sub>r, max</sub>'', mm) is as follows:
<math>d_{f, max}=\frac{\left[\left ( RVC_{T}\times R \right )+ RVC_{T}-\left(f'\times t\right )\right]}{n}</math>
<math>d_{r, max}=\frac{\left[\left ( RVC_{T}\times R \right )+ RVC_{T}-\left(f'\times t\right )\right]}{n}</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*''RVC<sub>T</sub>'' = [[Runoff volume control target]] (mm)
*''RVC<sub>T</sub>'' = [[Runoff volume control target]] (mm)
*''R'' = ''A<sub>c</sub>''/''A<sub>p</sub>''; the ratio of contributing drainage area (''A<sub>c</sub>'') to permeable paving area (''A<sub>p</sub>''). Note that the contributing drainage area (''A<sub>c</sub>'') should not contain pervious areas. R should not normally exceed 2.
*''R'' = ''A<sub>i</sub>''/''A<sub>p</sub>''; the ratio of impervious contributing drainage area (''A<sub>i</sub>'') to permeable pavement area (''A<sub>p</sub>''). Note that the contributing drainage area should not contain pervious areas. R should not normally exceed 2.
*''f''' = [[Design infiltration rate]] (mm/hr)
*''f''' = [[Design infiltration rate]] of underlying native soil (mm/hr)
*''t'' = Time to fill stone bed (typically 2 hr)
*''t'' = Duration of the design storm event (e.g., 2 hr)
*''n'' = Porosity of the stone bed aggregate material (typically 0.4 for 50 mm dia. [[reservoir aggregate|clear stone]])}}
*''n'' = Porosity of the stone bed aggregate material (typically 0.4 for 50 mm dia. [[reservoir aggregate|clear stone]])}}