Flow through perforated pipe

Manufacturers of perforated pipe are often able to provide the open area (m²) per meter length.

$Q_{max,p}=B\times C_{d}\times A_{o}{\sqrt {2\cdot g\cdot \sum d}}$

Where:_d is the coefficient of discharge (0.61 for a sharp edged orifice),

• B is the clogging factor (between 0.5 to calculate a for matured installation and 1 to calculate a new perfectly performing BMP),
• 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 of the perforated pipe (m²/m),
• g is acceleration due to gravity (m/s²)
• Σ d is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/mulch/filter media/choker layer),

Best management practice. State of the art methods or techniques used to manage the quantity and improve the quality of wet weather flow. BMPs include: source, conveyance and end-of-pipe controls.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.