Changes

The following calculation is used to size the stone storage bed (reservoir) used as a base course for designs without underdrains. It is assumed that the footprint of the stone bed will be equal to the footprint of the pavement. The following equations are taken from the ICPI Manual (Smith, 2006).  

The following calculation is used to size the stone storage bed (reservoir) used as a base course for designs without underdrains. It is assumed that the footprint of the stone bed will be equal to the footprint of the pavement. The following equations are taken from the ICPI Manual (Smith, 2006).  

The equation for the depth of the stone bed is as follows:  

The equation for the depth of the stone bed is as follows:  

              db= [Qc * R + P – i * T ] / Vr

 

        Where:  

<math>db= [Qc\times R + R - I\times T ] / V</math>

              db = Stone bed depth (m)  

where:

              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)

*''db'' &#61;  Stone bed depth (m)  

''Qc'' &#61;  Depth of runoff from contributing drainage area, not including permeable paving surface(m)  

''R'' &#61;  Ac/Ap = Ratio of contributing drainage area (Ac) to permeable paving area (Ap)

               P = Rainfall depth (m)  

               P = Rainfall depth (m)  

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

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