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→To calculate the total depth of the foundations (all aggregate layers)
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===To calculate the total depth of the foundations (all aggregate layers)===
===To calculate the total depth of the foundations (all aggregate layers)===
The equation for the depth of the stone foundation (d<sub>f, max</sub>) is as follows:
The equation for the depth of the stone foundation (''d<sub>f, max</sub>'', mm) is as follows:
<math>d_{f, max}=\frac{\left[\left ( Q_c\times R \right )+ P-\left(f'\times t\right )\right]}{V_{R}}</math>
<math>d_{f, max}=\frac{\left[\left ( Q_c\times R \right )+ P-\left(f'\times t\right )\right]}{V_{R}}</math>
{{Plainlist|1=Where:
{{Plainlist|1=Where:
*''Q<sub>c</sub>'' = Depth of runoff from contributing drainage area, not including permeable paving surface (m)
*''Q<sub>c</sub>'' = Depth of runoff from contributing drainage area, not including permeable paving surface (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'' = ''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.
*''P'' = Rainfall depth (m)
*''P'' = Rainfall depth (mm)
*''f''' = Design infiltration rate (m/day)
*''f''' = Design infiltration rate (mm/hr)
*''t'' = Time to fill stone bed (typically 2 hr)
*''t'' = Time to fill stone bed (typically 2 hr)
*''V<sub>R</sub>'' = Void ratio for stone bed (typically 0.4 for 50 mm dia. [[reservoir aggregate|clear stone]])}}
*''V<sub>R</sub>'' = Void ratio for stone bed (typically 0.4 for 50 mm dia. [[reservoir aggregate|clear stone]])}}