LOW IMPACT DEVELOPMENT STORMWATER MANAGEMENT PLANNING AND DESIGN GUIDE
VERSION 1.0
2010
By:
Credit Valley Conservation Authority (CVC) and
Toronto and Region Conservation Authority (TRCA)
Can be found on line at the following link:
http://www.creditvalleyca.ca/low-impact-development/low-impact-developmentsupport/stormwater-management-lid-guidance-documents/low-impact-development-stormwatermanagement-planning-and-design-guide/
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
RAIN WATER HARVESTING
The process in which rainwater is collected and stored in a rain barrel or storage tank for further
use. Typical uses can be for watering gardens and lawns as well as washing cars.
Some Considerations:
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Will freeze in the winter
Need to ensure that works meet local Plumbing Codes if required
Mosquitos in standing water
Child safety – need to secure the storage device, may need a lockable cover
Need to use the water collected before the next storm
Need to have overflow should the storage device fill up
www.cmhc-schl.gc.ca/
www.masterbuilder.co.in
http://static.squarespace.com
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
www.greenforwardnews.com
http://tunza.eco-generation.org
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
BIORETENTION – Rain Gardens
Bioretention temporarily stores, treats and infiltrations stormwater runoff.
The primary
component of bioretention is the filter bed which is a mixture of sand, fines and organic matter.
Other elements include mulch ground cover and plants.
Common considerations:
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Risk of groundwater contamination – salt, gas, oil
Performance in winter conditions – freezing
Maintenance of vegetation to ensure no clogging and proper establishment
Standing water and mosquitoes – ponding should not be longer than 24 hours.
Maximum depth – 150mm to 200 mm
Child safety – drowning
Set back from foundations at least 4 metres
Infiltration rate of soils
Need to provide overflow
www.thisoldhouse.com
http://srrcd.ca/
www.monsoonraingardens.com
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
INFILTRATION / SOAKAWAY
Trenches or pits lined with geotextile and filled with clear stone (with voids) which receive runoff
from a perforated pipe. Runoff is allowed to infiltrate into native soil. Typically for roof runoff in
residential areas. Can also receive overflow from rainwater harvesting.
Common considerations:
Risk of groundwater contamination – salt, gas, oil
Performance in winter conditions – freezing
Maintenance of vegetation to ensure no clogging and proper establishment
Standing water and mosquitoes – ponding should not be longer than 24 hours.
Maximum depth – 150mm to 200 mm
 Set back from foundations at least 4 metres
 Infiltration rate of soils
 Need to provide overflow
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www.sudswales.com
www.watershedmanagement.vt.gov/stormwater/images
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
VEGETATED FILTER STRIPS
Vegetated filter strips are gently sloping densely vegetated areas that treat runoff from adjacent
areas. They function by slowing runoff velocity and filtering out suspended sediments and
associated pollutants and by providing some infiltration into underlying soils. Can be composed
of trees, shrubs and plants.
Common considerations:
Risk of groundwater contamination – salt, gas, oil
Performance in winter conditions – freezing
Maintenance of vegetation to ensure no clogging and proper establishment
Standing water and mosquitoes – ponding should not be longer than 24 hours.
Maximum depth – 150mm to 200 mm
 Child safety – drowning
 Set back from foundations at least 4 metres
 Erosion – need to provide gentle slope
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http://nac.unl.edu/buffers/images
http://landperspectives.files.wordpress.com
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
PERMEABLE PAVEMENT
Permeable pavement allow stormwater to drain through them and into a stone reservoir where it
is infiltrated into the underlying native soil or temporarily detained. It can be used for low traffic
roads, walkways, parking lots and driveways.
Common considerations:
 Risk of groundwater contamination – salt, gas, oil
 Performance in winter conditions – freezing
 Standing water and mosquitoes – ponding should not be longer than 24 hours.
Maximum depth – 150mm to 200 mm
 Clogging – do not sand in the winter time
 Road salt – can migrate into the groundwater
 Structural stability – design guidelines for pavement design and base courses
 Not suitable for heavy traffic
 An underdrain may be required to allow for partial infiltration/detention.
www.vwrrc.vt.edu/swc
www.lastormwater.org
www.marshalls.co.uk
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.
OTHER ITEMS TO CONSIDER DURING THE DESIGN AND CONSTRUCTION PROCESS:
 Utility locates – prior to carrying out any works on any property it is required that the
property owner obtain locates for utilities. As there is various infrastructure in the
ground: telephone, cable TV, streetlight cable, hydro, gas, sewers and sewer services,
watermain and water services. All underground services need to be maintained and
work should respect proper setbacks to same.
 Culverts – can restrict flow and cause flooding if not sized properly, need to be
maintained to ensure that there is no sediment/garbage build up that may prevent flow of
water. If proposed on private property provision should be made for overflow should it
be necessary as any site alteration cannot adversely affect adjacent private property, as
noted above.
 Site Alteration – consideration is required during design and construction with regard to
impact on adjacent properties. The proposed works shall not interfere with the existing
drainage pattern of adjacent lands, or cause obstruction to existing drainage flows or
obstruct or impede the function or flow of existing drainage swales or cause additional
surface and ground waters to be discharged onto adjacent lands.
Information extracted from the Low Impact Development Stormwater Management Planning and Design Guide Version 1.0 2010
provided by the TRCA (Toronto and Region Conservation Authority) and CVC (Credit Valley Conservation) and websites as noted.