Talk:Enhanced Grass Swale Design Guide

LID Practice		CANADA			United States
Bioretention		CVC+TRCA (Factsheets-2010)	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
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)%,check dam for >3%	(0.5-4.0)%,check dam for >3%	(0.5-6.0) %, check dam for >3%
Bottom width (m)		0.75-3.0	0.75-3.0	0.75-3.0
Length		>= contributing roadway length
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 where space permits	Max. 2.5:1 , 4:1 is prefered	Max. 2.5:1 , 4:1 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 drainage area (%)		5-15		5-15
Depth between the bottom of the swale and high water table (m)		>= 1		>= 1
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

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Credit Valley Conservation

Toronto and Region Conservation Authority

Stormwater Management

Best management practice. State of the art methods or techniques used to manage the quantity and improve the quality of wet weather flow. BMPs include: source, conveyance and end-of-pipe controls.

A shallow constructed channel, often grass-lined, which is used as an alternative to curb and channel, or as a pretreatment to other measures. Swales are generally characterized by a broad top width to depth ratio and gentle grades.

Decayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil.

The slow movement of water into or through a soil or drainage system.

Penetration of water through the ground surface.

The portion of water precipitated onto a catchment area, which then flows as surface discharge from the catchment area past a specified point.

Water from rain, snow melt, or irrigation that flows over the land surface.

Mineral particles which are smaller than 2 mm, and which are free of appreciable quantities of clay and silt. Coarse sand usually designates sand grains with particle size between 0.2 and 0.02 mm.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Decayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil.

A hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil.

Natural or artificial means of intercepting and removing surface or subsurface water (usually by gravity).

Structures constructed of a non-erosive material, such as suitably sized aggregate, wood, gabions, riprap, or concrete; used to slow runoff water. Can be employed in practices such as bioswales and enhanced grass swales.

The total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds.

A shallow constructed channel, often grass-lined, which is used as an alternative to curb and channel, or as a pretreatment to other measures. Swales are generally characterized by a broad top width to depth ratio and gentle grades.

The upper surface of the zone of saturation, except where the surface is formed by an impermeable body.

Subsurface water level which is defined by the level below which all the spaces in the soil are filled with water; The entire region below the water table is called the saturated zone.

A shallow constructed channel, often grass-lined, which is used as an alternative to curb and channel, or as a pretreatment to other measures. Swales are generally characterized by a broad top width to depth ratio and gentle grades.

Vegetated, open channels designed to convey, treat and attenuate runoff. Design variations range from simple grass channels, which are designed primarily for conveyance to more complex treatment and volume reduction designs like enhanced grass swales, and dry swales or bioswales.

The period between the maximum water level and the minimum level (dry weather or antecedent level).

Mineral particles which are smaller than 2 mm, and which are free of appreciable quantities of clay and silt. Coarse sand usually designates sand grains with particle size between 0.2 and 0.02 mm.

Soil particles with a diameter less than 0.050 mm.

Soil or media particles smaller than sand and larger than clay (3 to 60 m)

1. A mineral soil separate consisting of particles less than 0.002 millimeter in equivalent diameter. 2. A soil texture class. 3. (Engineering) A fine-grained soil (more than 50 percent passing the No. 200 Sieve) that has a high plasticity index in relation to the liquid limit. (Unified Soil Classification System).