Difference between revisions of "Site considerations"

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!Installations type
 
!Installations type
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!Depth to high Water or bedrock (m)<ref>Minimum depth between the base of the facility and the elevation of the seasonally high water table or top of bedrock</ref>
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!Depth to high water or bedrock (m)<ref>Minimum depth between the base of the facility and the elevation of the seasonally high water table or top of bedrock</ref>
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!Typical ratio of <br>Impervious Drainage Area<br> to Treatment Facility Area
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!Typical ratio of <br>Impervious drainage area<br> to Treatment Facility Area
 
!Native soil infiltration rate (mm/hr)<ref>Infiltration rate estimates based on measurements of hydraulic conductivity under field saturated conditions at the proposed location and depth of the practice</ref>
 
!Native soil infiltration rate (mm/hr)<ref>Infiltration rate estimates based on measurements of hydraulic conductivity under field saturated conditions at the proposed location and depth of the practice</ref>
 
!Head (m)<ref>Vertical distance between the inlet and outlet of the LID practice</ref>
 
!Head (m)<ref>Vertical distance between the inlet and outlet of the LID practice</ref>

Revision as of 15:25, 31 January 2019

Installations type Depth to high water or bedrock (m)[1] Typical ratio of
Impervious drainage area
to Treatment Facility Area 		Native soil infiltration rate (mm/hr)[2] Head (m)[3] Space % [4] Slope % [5] Applicable in pollution hotspots [6] Set backs Water table [7] Wellhead protection area[8]
Rain Barrel Not applicable 5 to 50 m2 Not applicable 1 0 NA Yes None None None
Cistern Not applicable 1:1 Not applicable 0 0 0 Yes None None None
Roof downspout disconnection Not applicable 5 to 100 m2 Amend if < 15 mm/hr 0.5 5 to 20 1 to 5 Yes Building Foundation None None
Soakaway, infiltration trench or chamber 1 5:1 to 20:1 Not a constraint 1 to 2 0 to 1 <15 % No 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas		 1 m 2 yr
Bioretention 1 5:1 to 15:1 Underdrain required
if < 15 mm/hr		 1 to 2 5 to 10 0 to 2 No 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas		 1 m 2 yr
Stormwater planters Not applicable 5:1 Not applicable 1 to 2 2 to 5 0 to 2 Yes Building Foundation, Trees None None
Vegetated filter strip 1 5:1 Amend if < 15 mm/hr 0 to 1 15 to 20 1 to 5 No None None None
Permeable pavement 1 1:1 to 1.2:1 Underdrain Required
if < 15 mm/hr		 0.5 to 1 0 1 to 5 No 4m-Underground Utilities
Drinking Water Wellhead
Protection Areas		 1 m 2 Yr
Enhanced grass swale (has checkdams) 1 5:1 to 10:1 Not applicable 1 to 3 5 to 15 0.5 to 6 No 4m- Building Foundation
Underground Utilities		 1 m None
Dry swale (Bioswale) 1 5:1 to 15:1 Underdrain Required
if < 15 mm/hr		 1 to 3 5 to 10 0.5 to 6 No 4m (3m if impermeable liner
is used)Building foundation,
Underground utilities, drinking
water wellhead protection areas		 1 m 2 Yr
Perforated pipe system 1 5:1 to 10:1 Not a constraint 1 to 3 0 < 15% No 4m- Building Foundation
Underground Utilities, Trees,
Drinking Water Wellhead
Protection Areas		 1 m 2 Yr
  1. ↑ Minimum depth between the base of the facility and the elevation of the seasonally high water table or top of bedrock
  2. ↑ Infiltration rate estimates based on measurements of hydraulic conductivity under field saturated conditions at the proposed location and depth of the practice
  3. ↑ Vertical distance between the inlet and outlet of the LID practice
  4. ↑ Percent of open pervious land on the site that is required for the LID practice
  5. ↑ Slope at the LID practice location
  6. ↑ Suitable in pollution hot spots or runoff source areas where land uses or activities have the potential to generate highly contaminated runoff
  7. ↑ Separated from the seasonally high water table or top of bedrock elevation
  8. ↑ |Time-of-travel within wellhead protection areas

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

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.

The natural ground material characteristic of or existing by virtue of geographic origin.

The rate at which stormwater percolates into the subsoil measured in inches per hour.

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.

Tank used to store rainwater (typically roof runoff) for later use.

An underground water storage reservoir into which stormwater is directed and allowed to percolate into the underlying native subsoil.

An excavated area lined with geotextile filter cloth and filled with clean granular stone or other void forming material, that receives runoff and allow it to infiltrate into the native soil; can also be referred to as infiltration galleries, French drains, dry wells or soakaway pits.

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

A perforated pipe used to assist the draining of soils.

a gently sloping, densely vegetated areas that treat runoff as sheet flow from adjacent impervious areas. They function by slowing runoff velocity and filtering out suspended sediment and associated pollutants, and by providing some infiltration into underlying soils.

An alternative practice to traditional impervious pavement, prevents the generation of runoff by allowing precipitation falling on the surface to infiltrate through the surface course into an underlying stone reservoir and, where suitable conditions exist, into the native soil.

Vegetated open channel, with check dams; designed to convey, treat and attenuate stormwater runoff.

Linear bioretention cell designed to convey, treat and attenuate stormwater runoff. The engineered filter media soil mixture and vegetation slows the runoff water to allow sedimentation, filtration through the root zone, evapotranspiration, and infiltration into the underlying native soil.

Linear bioretention cell designed to convey, treat and attenuate stormwater runoff. The engineered filter media soil mixture and vegetation slows the runoff water to allow sedimentation, filtration through the root zone, evapotranspiration, and infiltration into the underlying native soil.

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.

The rate at which stormwater percolates into the subsoil measured in inches per hour.

A parameter that describes the capability of a medium to transmit water.

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.

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.

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