Changes

*''d'' = Stone bed depth (m)  

*''d'' = Stone bed depth (m)  

*''Qc'' = Depth of runoff from contributing drainage area, not including permeable paving surface(m)  

*''Qc'' = Depth of runoff from contributing drainage area, not including permeable paving surface(m)  

*''R'' =  Ac/Ap = Ratio of contributing drainage area (Ac) to permeable paving area (Ap)

*''R'' =  A_c/A_p = Ratio of contributing drainage area (A_c) to permeable paving area (A_p)

*''P'' =  Rainfall depth (m)  

*''P'' =  Rainfall depth (m)  

*''i'' =  Infiltration rate for native soils (m/day)  

*''i'' =  Infiltration rate for native soils (m/day)  

Note that the contributing drainage area (Ac) should not contain pervious areas.

Note that the contributing drainage area (Ac) should not contain pervious areas.

For designs that include an underdrain, the maximum depth of the stone reservoir below the invert of the underdrain pipe can be calculated as follows:  

For designs that include an underdrain, the maximum depth of the stone reservoir below the invert of the underdrain pipe can be calculated as follows:  

<math>dr_{max} = [i \times t] / Vr </math>

<math>dr_{max} = \frac{[i \times t]}{Vr} </math>

Where:  

Where:  

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