Changes

Manufacturers of perforated pipe are often able to provide the open area per meter length. Where this information is not directly available, the open area can be calculated by measuring the perforations and summing the open are per meter. The maximum flow rate through a perforated pipe (''Q_{max, p}'', L/s) may be calculated:  

Manufacturers of perforated pipe are often able to provide the open area per meter length. Where this information is not directly available, the open area can be calculated by measuring the perforations and summing the open are per meter. The maximum flow rate through a perforated pipe (''Q_{max, p}'', L/s) may be calculated:  

<math>Q_{max, p}=\frac{L\times B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot \sum d}}{1000}</math>

<math>Q_{max, p}=\frac{L\times B\times C_{d}\times A_{o}\sqrt{2\cdot g\cdot h_{max}}}{1000}</math>

{{Plainlist|1=Where:

{{Plainlist|1=Where:

*''L'' is the length of perforated pipe (m)

*''L'' is the length of perforated pipe (m)

*''C_d'' is the coefficient of discharge (usually 0.61 for the sharp edge created by relatively thin pipe walls),  

*''C_d'' is the coefficient of discharge (usually 0.61 for the sharp edge created by relatively thin pipe walls),  

*''A_o'' is the total open area per unit length of pipe (m²/m),  

*''A_o'' is the total open area per unit length of pipe (m²/m),  

*''g'' is acceleration due to gravity (m/s²)  

*''g'' is acceleration due to gravity (m/s²), and

*''Σ d'' is the total depth of bioretention components over the perforated pipe (m) (e.g. ponding/[[mulch]]/[[filter media]]/[[choker layer]]),

*''h_max'' is the total head of water within bioretention components over the perforated pipe (m) (i.e. ponding + [[mulch]] + [[filter media]] + [[choker layer]]).

}}

}}