Difference between revisions of "Flow through media"

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The maximum flow rate through a bed of filer media (''Q<sub>max</sub>'') may be calculated:
 
The maximum flow rate through a bed of filer media (''Q<sub>max</sub>'') may be calculated:
<math>Q_{max}=K_{m}\times A_{p}\times \left (\frac{d_{p}+d_{m}}{d_{m}}  \right )\times 3.6 \times 10^{-3}</math>
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<math>Q_{max}=K_{m}\times A_{p}\times \left (\frac{\sum d}{d_{m}}  \right )\times 3.6 \times 10^{-3}</math>
 
{{Plainlist|1=Where:
 
{{Plainlist|1=Where:
 
*''K<sub>m</sub>'' is the hydraulic conductivity of the filter media (mm/hr),  
 
*''K<sub>m</sub>'' is the hydraulic conductivity of the filter media (mm/hr),  
 
*''A<sub>p</sub>'' is the area of the practice (m<sup>2</sup>),  
 
*''A<sub>p</sub>'' is the area of the practice (m<sup>2</sup>),  
*''Σ d<sub>z</sub>'' is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/[[mulch]]/[[filter media]]/[[choker layer]]),  
+
*''Σ d'' is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/[[mulch]]/[[filter media]]/[[choker layer]]),  
 
*''d<sub>m</sub>'' is the depth of the filter media (mm), and  
 
*''d<sub>m</sub>'' is the depth of the filter media (mm), and  
 
}}
 
}}

Revision as of 02:36, 25 February 2018

Practices which infiltrate surface runoff through an engineered soil or filter media, and discharge through an underdrain include stormwater planters and some forms of bioretention. The maximum flow rate from the BMP may be limited by the hydraulic conductivity of the mmedium, or by the properties of the perforated pipe.

The maximum flow rate through a bed of filer media (Qmax) may be calculated:

Where:

  • Km is the hydraulic conductivity of the filter media (mm/hr),
  • Ap is the area of the practice (m2),
  • Σ d is the total depth of bioretention components over the perforated pipe (mm) (e.g. ponding/mulch/filter media/choker layer),
  • dm is the depth of the filter media (mm), and