Talk:Enhanced Grass Swale Design Guide

From LID SWM Planning and Design Guide
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Enhanced grass swales CVC+TRCA Toronto- 2016 LID-SWM Guide 2010 New York State SWM Design Manual-2015 Massachusets SW BMP-2013 District of Columbia-SWM Guidebook-2010 San Diego LID Handbook-2014 Alabama LID Handbook-2013 W. Virginia-SWM design guidance manual-2012 Tennessee-LID Development-SWM 2016 Texas-LID Technical Guidance Manual-2013 Oregon SWM Manual-2014 Oregon State Univ. Fact Sheets-2011
Factsheets-2010
Swale length between culverts >= 5 >= 5 >= 5 Can amend with 2" of soil media or plant-derived compost to increase infiltration < 5 acres, capture runoff from 10-20% of the IPCDA, soil could also be 50/50 sand soil mix instead of bioretention media Compost amendments over full length and width
Max. Velocity For 4 hr. 25 mm(Chicago) 0.5 m/s 0.5 m/s 0.5 m/s
Setback from building Foundation(m) 4 4
(Impervious drainage/treatment) area 5:1 to 10:1 5:1 to 10:1 CDA < 5 acres and WQV peak flow < 3 cfs CDA < 2.5 acres CDA <15000 ft2
longitudinal slope (0.5-4.0) % (0.5-4.0) % (0.5-6.0) %, (0.5-4)
check dam for >3% check dam for >3% check dam for >3%
Bottom width (m) 0.75-3.0 0.75-3.0 0.75-3.0
Length >= contributing
roadway lengt
Flow depth (mm) (25 mm Chicago storm event) max 100 (25 mm storm) max 100 (25 mm storm) max 100 (25 mm storm)
Side slope (H:V) Max. 2.5:1 , 4:1 Max. 2.5:1 , 4:1 is prefered Max. 2.5:1 , 4:1
where space permits where space permits
Soil Amendments
depth (mm) 300 300 300
Oganic content 8-15% by weight 8-15% by weight 8-15% by weight 3-15% 5-10 %
Grass height (mm) 75-150 150
Gravel diaphram
Diameter (mm) 3-10 3-10
Min. Wide (mm) 300 300
Min. Deep (mm) 600 600
Available space of the contributing 5-15 5-15
drainage area (%)
Depth between the bottom of the >= 1 >= 1
swale and high water table (m)
Enhanced grass swales area/contributing road surface 1:1
Drainage time of ponded water after the end of storm event , hr < = 24
CDA or Impervious ratio < 5 acres < 2.5 acres
Filter Media
Sand 50% 85-88% 70-85 % 66% 60%
Loam 50%
Soil Fines 8-12% 10-20% (silt), max. 10% (clay)
Organic 5-10 % > 5% otherwise amend 2" with media 33% 40%
CEC > 10 > 5
pH 5.5-7.5