Difference between revisions of "Bioretention: Sizing and modeling"

From LID SWM Planning and Design Guide
Jump to navigation Jump to search
Line 1: Line 1:
<ol>
Input data:  
<li>Input data:  
*The applicable infiltration coefficient (''q'') is calculated by applying a [[Infiltration: Testing|safety factor to the measured infiltration rate]].
<ul>
*Determine the impervious catchment area (''I''), and outline the location of the bioretention facility. To begin with, budget for at least 10% of the total catchment area to be required for the BMP. The area of the facility on the ground will be 'P' (pervious).
<li>The applicable infiltration coefficient (q) is calculated by applying a [[Infiltration: Testing|safety factor to the measured infiltration rate]].</li>
*Unless the biomedia fill material has been tested and certified otherwise, a porosity value (''n'') of 0.35 may be assumed (i.e. void ratio 35%).
<li>Determine the drainage catchment area (A<sub>D</sub>), and outline the location of the bioretention facility. To begin with, budget for at least 10% of the contributing impervious area to be required for the BMP. </li></li>
*Bioretention facilities are usually between 0.5 m and 1.25 m deep, owing to construction considerations. Determine the maximum available depth (''c<sub>c max</sub>'') from the site constraints. The [[Infiltration]] page lists these.  
<li>Unless the biomedia fill material has been tested and certified otherwise, a porosity value (V<sub>r</sub>) of 0.4 may be assumed (i.e. void ratio 40%). </li>
Identify the duration (''D'') and intensity (''i'') of design storm(s).
<li>Bioretention facilities are usually between 0.5 m and 1.25 m deep, owing to construction considerations. Determine the maximum available depth (c<sub>c max</sub>) from the site constraints. The [[Infiltration]] page lists these. </li>
Calculate the required pervious area
<li>Identify the duration (D) and intensity (i) of design storm(s). </li></ul>
 
<li>Calculate the required area</li>
<math>d_{f}=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math>
</ol>
 
<strong>[[Media:Infiltration Sizing.xlsx|Download .xlsx calculation tool]]</strong>
<strong>[[Media:Infiltration Sizing.xlsx|Download .xlsx calculation tool]]</strong>
[[category: modeling]]
[[category: modeling]]
[[category: infiltration]]
[[category: infiltration]]

Revision as of 23:12, 17 August 2017

Input data:

  • The applicable infiltration coefficient (q) is calculated by applying a safety factor to the measured infiltration rate.
  • Determine the impervious catchment area (I), and outline the location of the bioretention facility. To begin with, budget for at least 10% of the total catchment area to be required for the BMP. The area of the facility on the ground will be 'P' (pervious).
  • Unless the biomedia fill material has been tested and certified otherwise, a porosity value (n) of 0.35 may be assumed (i.e. void ratio 35%).
  • Bioretention facilities are usually between 0.5 m and 1.25 m deep, owing to construction considerations. Determine the maximum available depth (cc max) from the site constraints. The Infiltration page lists these.

Identify the duration (D) and intensity (i) of design storm(s). Calculate the required pervious area

Download .xlsx calculation tool