Difference between revisions of "Bioretention: TTT"

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Suggested ranges:
 
Suggested ranges:
 
* [[Turf: List|Mown grass]] (dependent on density) 0.03 – 0.06<ref name = SWMM> Oregon State Univ., Corvallis. Dept. of Civil, Construction and Environmental Engineering.; Environmental Protection Agency, Cincinnati ONRMRL. Storm Water Management Model Reference Manual Volume I Hydrology (Revised). 2016:233. https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100NYRA.txt  Accessed August 23, 2017.</ref>
 
* [[Turf: List|Mown grass]] (dependent on density) 0.03 – 0.06<ref name = SWMM> Oregon State Univ., Corvallis. Dept. of Civil, Construction and Environmental Engineering.; Environmental Protection Agency, Cincinnati ONRMRL. Storm Water Management Model Reference Manual Volume I Hydrology (Revised). 2016:233. https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100NYRA.txt  Accessed August 23, 2017.</ref>
* [[Stones]] 0.03 – 0.05
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* [[Stone]]s 0.03 – 0.05
 
* Planted (highly dependent on density) 0.05 – 0.15
 
* Planted (highly dependent on density) 0.05 – 0.15
 
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|-
 
|-
 
|Thickness (mm)
 
|Thickness (mm)
|Depth of filter media
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|Depth of [[filter media]]
 
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|-
 
|Porosity (fraction)
 
|Porosity (fraction)
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|-
 
|-
 
|Seepage rate (mm/hr)
 
|Seepage rate (mm/hr)
|Infiltration rate of native soil  
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|Design infiltration rate of native soil  
 
|-
 
|-
 
|Clogging factor
 
|Clogging factor

Revision as of 02:42, 9 November 2017

TTT.png

Bioretention cells are found within the LID toolbox
Surface
Berm height (mm) Sometimes referred to as the bowl depth
Surface roughness (Manning’s n) Lower numbers indicate less surface obstruction and result in faster flow

Suggested ranges:

  • Mown grass (dependent on density) 0.03 – 0.06[1]
  • Stones 0.03 – 0.05
  • Planted (highly dependent on density) 0.05 – 0.15
Surface slope (%) If the slope > 3% a series of Check dams or weirs should be included in the design.
Soil (bioretention filter media)
Thickness (mm) Depth of filter media
Porosity (fraction) Suggest range 0.35 – 0.4 unless otherwise tested
Field capacity (fraction) Suggested range 0.10 - 0.12 [1]
Wilting point (fraction) Suggested value 0.03 [1]
Conductivity (mm/hr) Suggested range 25 – 250 mm/hr
Conductivity slope Suggested value 45 [1]
Suction head (mm) Suggested range 50 - 60 [1]
Storage
Thickness (mm) Depth of storage aggregates layer
Void ratio Suggest range 0.35 – 0.4 unless otherwise tested
Seepage rate (mm/hr) Design infiltration rate of native soil
Clogging factor ?
Design drawdown time (hrs) Also known as 'drainage time'
Drain (underdrain)
Flow coefficient Suggested value 1
Flow exponent Suggested value 1
Offset height This is the height from the base of the cell to the height at which the drain discharges. In some designs this may be the height of the perforated pipe within the storage layer; in others this height is adjusted by creating an upturn in the discharge pipe.Bioretention: Partial infiltration
  1. 1.0 1.1 1.2 1.3 1.4 Oregon State Univ., Corvallis. Dept. of Civil, Construction and Environmental Engineering.; Environmental Protection Agency, Cincinnati ONRMRL. Storm Water Management Model Reference Manual Volume I Hydrology (Revised). 2016:233. https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100NYRA.txt Accessed August 23, 2017.