Difference between revisions of "Bioretention: Sizing and modeling"
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*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). | *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%). | *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 ('' | *Bioretention facilities are usually between 0.5 m and 1.25 m deep, owing to construction considerations. Determine the maximum available depth of the facility (''d<sub>f max</sub>'') from the site constraints. The [[Infiltration]] page lists these. | ||
Identify the duration (''D'') and intensity (''i'') of design storm(s). | Identify the duration (''D'') and intensity (''i'') of design storm(s). | ||
Calculate the required | Calculate the required facility area (''P''). | ||
<math>d_{f}=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math> | <math>d_{f}=\frac{D\left (\left [ I/P \right ]i-q \right )}{n}</math> | ||
Revision as of 23:14, 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 of the facility (df max) from the site constraints. The Infiltration page lists these.
Identify the duration (D) and intensity (i) of design storm(s). Calculate the required facility area (P).
![{\displaystyle d_{f}={\frac {D\left(\left[I/P\right]i-q\right)}{n}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/1539513afe21c0fcb19bb49d2f6d2064e6c79f8d)