Changes

*''T'' = Time to fill stone bed (typically 2 hr)  

*''T'' = Time to fill stone bed (typically 2 hr)  

*''Vr'' = Void ratio for stone bed (typically 0.35 for 50 mm dia. stone)}}  

*''Vr'' = Void ratio for stone bed (typically 0.35 for 50 mm dia. stone)}}  

 

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} = \frac{q \times t}{Vr}</math>  

<math>dr_{max} = \frac{q \times t}{Vr}</math>