Difference between revisions of "Swales: TTT"

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{{Clickable button|[[File:TTT.png|400 px|link=http://www.sustainabletechnologies.ca/wp/low-impact-development-treatment-train-tool/]]}}
{{Clickable button|[[File:TTT.png|400 px|link=http://www.sustainabletechnologies.ca/wp/low-impact-development-treatment-train-tool/]]}}
[[File:Swale TTT.png|thumb|Swale element in TTT menu]]
[[File:Swale TTT.png|thumb|Swale element in TTT menu]]
[[Outfall TTT.png|thumb|Outfall element in the TTT menu]]
[[File:Weir TTT.png|thumb|Weir elements may be incorporated as checkdams]]
[[File:Weir TTT.png|thumb|Weir elements may be incorporated as checkdams]]


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For detailed scenarios of enhanced swales, the weir element can be incorporated for checkdams.  
For detailed scenarios of enhanced swales, the weir element can be incorporated for checkdams.  
The alternative is to use the 'enhanced swale' within the LID toolbox, but this incorporates fewer design parameters.  
The alternative is to use the 'enhanced swale' within the LID toolbox, but this incorporates fewer design parameters.  
A 'swale' has to connect two existing elements within the TTT. Where another element isn't specified an 'outfall' can be used. 


{| class="wikitable"
{| class="wikitable"
|+Parameters for 'Swale' elements in the TTT
|+A 'swale' as a conveyance element in the TTT (key parameters)
|-
|Name||User-assigned swale name
|-
|-
|Upstream Node||Name of node on the inlet end of the swale (which is normally the end at higher elevation)
|Upstream Node||Name of node on the inlet end of the swale (higher elevation)
|-
|-
|Downstream Node||Name of node on the outlet end of the swale (which is normally the end at lower elevation)
|Downstream Node||Name of node on the outlet end of the swale (lower elevation)
|-
|-
|Length (m)||Length of the swale
|Length (m)||Length of the swale
|-
|-
|Manning's Roughness||Manning's roughness coefficient
|Manning's Roughness||Lower numbers indicate less surface obstruction and result in faster flow. <br>
Suggested range for 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>
|-
|-
|Upstream Invert Offset (m)||Depth of swale invert above node invert at inlet end of the swale
|Upstream Invert Offset (m)||Depth of swale invert above node invert at inlet end of the swale
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|Bottom Width (m)||Bottom width of the trapezoidal swale (i.e., open channel)<br> For a triangular channel, enter 0
|Bottom Width (m)||Bottom width of the trapezoidal swale (i.e., open channel)<br> For a triangular channel, enter 0
|-
|-
|Left Side Slope (m/m)||Left side slope (run/rise)
|Left Side Slope (m/m)||Left side slope (run/rise). Suggested value of 3 or 4 if design permits. [[Enhanced swales]]
|-
|-
|Right Side Slope (m/m)||Right side slope (run/rise)
|Right Side Slope (m/m)||Right side slope (run/rise). Suggested value of 3 or 4 if design permits.
|-
|-
|Seepage (mm/hour)||Rate of seepage loss into the surrounding soil
|Seepage (mm/hour)||Infiltration rate of native (or amended) soil
|}
|}



Revision as of 15:27, 18 September 2017

TTT.png

Swale element in TTT menu

thumb|Outfall element in the TTT menu

Weir elements may be incorporated as checkdams

It is recommended that swales be modelled as a 'Swale', which has it's own menu button in the TTT. For detailed scenarios of enhanced swales, the weir element can be incorporated for checkdams. The alternative is to use the 'enhanced swale' within the LID toolbox, but this incorporates fewer design parameters.

A 'swale' has to connect two existing elements within the TTT. Where another element isn't specified an 'outfall' can be used.

A 'swale' as a conveyance element in the TTT (key parameters)
Upstream Node Name of node on the inlet end of the swale (higher elevation)
Downstream Node Name of node on the outlet end of the swale (lower elevation)
Length (m) Length of the swale
Manning's Roughness Lower numbers indicate less surface obstruction and result in faster flow.

Suggested range for mown grass (dependent on density) 0.03 – 0.06 [1]

Upstream Invert Offset (m) Depth of swale invert above node invert at inlet end of the swale
Downstream Invert Offset (m) Depth or elevation of the swale invert above the node invert at the outlet end of the swale
Depth (m) Depth of the swale
Bottom Width (m) Bottom width of the trapezoidal swale (i.e., open channel)
For a triangular channel, enter 0
Left Side Slope (m/m) Left side slope (run/rise). Suggested value of 3 or 4 if design permits. Enhanced swales
Right Side Slope (m/m) Right side slope (run/rise). Suggested value of 3 or 4 if design permits.
Seepage (mm/hour) Infiltration rate of native (or amended) soil

The TTT also includes an 'enhanced swale' element within the LID toolbox. In version 1.0 this element does not incorporate checkdams and doesn't account for any infiltration capacity.

Parameters for 'enhanced swales' in the LID toolbox of the TTT
Surface
Berm height (mm) This is the height of the curb which constrains the overland sheet flow of water. Where the bottom of the slope discharges directly into another LID facility without impedance, the value is 0.
Surface roughness (Manning’s n) Lower numbers indicate less surface obstruction and result in faster flow.

Suggested range for mown grass (dependent on density) 0.03 – 0.06 [1]

Surface slope (%) If the slope > 3%, consider using small Checkdams or weirs to permit temporary ponding, increase infiltration, and slow flow to reduce erosion.
Swale side slopes (run/rise) Suggested value of 3 or 4 if design permits Enhanced swales
  1. 1.0 1.1 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.