Changes

![[Winter]] operations

![[Winter]] operations

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!Roof Downspout Disconnection

!Roof downspout disconnection

|Simple [[downspout disconnection]] requires a minimum flow path length across the pervious area (at least 5 metres) and suitable soil conditions. If the flow path length is less than 5 m and soils are hydrologic soil group (HSG) C or D, roof downspouts should be directed to another LID practice such as a rainwater harvesting system, soakaway, swale, bioretention area or perforated pipe system.

|Simple [[downspout disconnection]] requires a minimum flow path length across the pervious area (at least 5 metres) and suitable soil conditions. If the flow path length is less than 5 m and soils are hydrologic soil group (HSG) C or D, roof downspouts should be directed to another LID practice such as a rainwater harvesting system, soakaway, swale, bioretention area or perforated pipe system.

|Disconnected downspouts should discharge to a gradual slope that conveys runoff away from the building. The slope should be between 1% and 5%. Grading should discourage flow from reconnecting with adjacent impervious surfaces

|Disconnected downspouts should discharge to a gradual slope that conveys runoff away from the building. The slope should be between 1% and 5%. Grading should discourage flow from reconnecting with adjacent impervious surfaces.

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|If the infiltration rate of soils in the pervious area is less than 15 mm/hr, they should be tilled to a depth of 300 mm and amended with compost to achieve an organic content in the range of 8 to 15% by weight or 30 to 40 % by volume.

|If the infiltration rate of soils in the pervious area is less than 15 mm/hr, they should be tilled to a depth of 300 mm and amended with compost to achieve an organic content in the range of 8 to 15% by weight or 30 to 40 % by volume.

|Downspout disconnection can be used where land uses or activities at ground-level have the potential to generate highly contaminated runoff as long as the roof runoff is kept separate from runoff from ground level impervious surfaces

|Downspout disconnection can be used where land uses or activities at ground-level have the potential to generate highly contaminated runoff as long as the roof runoff is kept separate from runoff from ground level impervious surfaces.

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|For simple downspout disconnection the roof drainage area should not be greater than 100 m²

|For simple downspout disconnection the roof drainage area should not be greater than 100 m².

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!Soakaways, Infiltration Trenches and Chambers

!Soakaways, Infiltration Trenches and Chambers

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|Facilities cannot be located on natural slopes greater than 15%

|Facilities cannot be located on natural slopes greater than 15 %.

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|[[Soakaways]], [[infiltration trenches]] and [[chambers]] can be constructed over any soil type, but [[hydrologic soil group]] A or B soils are best for achieving water balance and channel erosion control objectives. If possible, facilities should be located in portions of the site with the highest native soil infiltration rates.

|[[Soakaways]], [[infiltration trenches]] and [[chambers]] can be constructed over any soil type, but [[hydrologic soil group]] A or B soils are best for achieving water balance and channel erosion control objectives. If possible, facilities should be located in portions of the site with the highest native soil infiltration rates.

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by soakaways, infiltration trenches or chambers.

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by soakaways, infiltration trenches or chambers.

|Facilities should be setback a minimum of 4 from building foundations.

|Facilities should be setback a minimum of 4 m from building foundations.

|Local utility design guidance should be consulted to define the horizontal and vertical offsets. Generally, requirements for underground utilities passing near the practice will be no different than for utilities in other pervious areas

|Local utility design guidance should be consulted to define the horizontal and vertical offsets. Generally, requirements for underground utilities passing near the practice will be no different than for utilities in other pervious areas

|They can be designed with an impervious drainage area to treatment facility area ratio of between 5:1 and 20:1. A maximum ratio of 10:1 is recommended for facilities receiving road or parking lot runoff

|They can be designed with an impervious drainage area to treatment facility area ratio of between 5:1 and 20:1. A maximum ratio of 10:1 is recommended for facilities receiving road or parking lot runoff

|If an impermeable liner is used, no setback is needed. If not, a four 4 m setback from buildings should be applied

|If an impermeable liner is used, no setback is needed. If not, a four 4 m setback from buildings should be applied

|Designers should consult local utility design guidance for the horizontal and vertical clearances required between storm drains, ditches, and surface water bodies. It is feasible for on-site utilities to cross linear bioretention; however, this may require design of special protection for the utility. For road right-of-way applications, care should be taken to provide utility specific horizontal and vertical offsets

|Designers should consult local utility design guidance for the horizontal and vertical clearances required between storm drains, ditches, and surface water bodies. It is feasible for on-site utilities to cross linear bioretention; however, this may require design of special protection for the utility. For road right-of-way applications, care should be taken to provide utility specific horizontal and vertical offsets

|Bioretention cells work best for smaller drainage areas, as flow distribution over the filter bed is easier to achieve. Typical drainage areas are between 100 m² to 0.5 hectares. The maximum recommended drainage area to one bioretention facility is approximately 0.8 hectares (Davis et al., 2009). Ideally, bioretention should be used as a source control for small drainage areas and not as an end of pipe control. Typical ratios of impervious drainage area to bioretention cell area range from 5:1 to 15:1.

|Bioretention cells work best for smaller drainage areas, as flow distribution over the filter bed is easier to achieve. Typical drainage areas are between 100 m² to 0.5 Ha. The maximum recommended drainage area to one bioretention facility is approximately 0.8 Ha (Davis et al., 2009). Ideally, bioretention should be used as a source control for small drainage areas and not as an end of pipe control. Typical ratios of impervious drainage area to bioretention cell area range from 5:1 to 15:1.

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Bioretention should be separated from the seasonally high water table by a minimum of 1 m to ensure groundwater does not intersect the filter bed.

|Bioretention should be separated from the seasonally high water table by a minimum of 1 m to ensure groundwater does not intersect the filter bed.

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!Permeable Pavement

!Permeable pavement

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|The slope of the permeable pavement surface should be at least one percent and no greater than five percent. The impervious land surrounding and draining into the pavement should not exceed 20% slope

|The slope of the permeable pavement surface should be at least one percent and no greater than five percent. The impervious land surrounding and draining into the pavement should not exceed 20 % slope.

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|Systems located in low permeability soils with an infiltration rate of less than 15 mm/hr, require incorporation of a perforated pipe underdrain

|Systems located in low permeability soils with an infiltration rate of less than 15 mm/hr, require incorporation of a perforated pipe underdrain.

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by permeable pavement

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by permeable pavement

|Permeable pavement should be located downslope from building foundations. If the pavement does not receive runoff from other surfaces, no setback is required from building foundations. Otherwise, a minimum setback of four 4 m down-gradient from building foundations is recommended.

|Permeable pavement should be located downslope from building foundations. If the pavement does not receive runoff from other surfaces, no setback is required from building foundations. Otherwise, a minimum setback of four 4 m down-gradient from building foundations is recommended.

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|Sand or other granular materials should not be applied as anti-skid agents during winter operation because they can quickly clog the system. Winter maintenance practices should be limited to plowing, with [[de-icing]] salt applied sparingly

|Sand or other granular materials should not be applied as anti-skid agents during winter operation because they can quickly clog the system. Winter maintenance practices should be limited to plowing, with [[Salt management|de-icing salt]] applied sparingly.

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!Enhanced Swales

!Enhanced swales

|Grass [[swales]] usually consume about 5 - 15 % of their contributing drainage area. A width of at least 2 m is needed.

|Grass [[swales]] usually consume about 5 - 15 % of their contributing drainage area. A width of at least 2 m is needed.

|Site topography constrains the application of grass swales. Longitudinal slopes between 0.5 - 6% are allowable. This prevents ponding while providing residence time and preventing erosion. On slopes steeper than 3%, [[check dams]] should be used

|Site topography constrains the application of grass swales. Longitudinal slopes between 0.5 - 6% are allowable. This prevents ponding while providing residence time and preventing erosion. On slopes steeper than 3%, [[check dams]] should be used.

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|Grass swales can be applied on sites with any type of soils

|Grass swales can be applied on sites with any type of soils

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by grass swales.

|To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoff should not be treated by grass swales.

|Enhanced grass swales should be located a minimum of 4 m from building foundations to prevent water damage.

|Enhanced grass swales should be located a minimum of 4 m from building foundations to prevent water damage.

|Utilities running parallel to the grass swale should be offset from the centerline of the swale. Underground utilities below the bottom of the swale are not a problem.

|Utilities running parallel to the grass swale should be offset from the centre line of the swale. Underground utilities below the bottom of the swale are not a problem.

|The conveyance capacity should match the drainage area. Sheet flow to the grass swale is preferable. If drainage areas are greater than 2 hectares, high discharge through the swale may not allow for filtering and infiltration, and may create erosive conditions. Typical ratios of impervious drainage area to swale area range from 5:1 to 10:1.

|The conveyance capacity should match the drainage area. Sheet flow to the grass swale is preferable. If drainage areas are greater than 2 hectares, high discharge through the swale may not allow for filtering and infiltration, and may create erosive conditions. Typical ratios of impervious drainage area to swale area range from 5:1 to 10:1.

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|Designers should ensure that the bottom of the swale is separated from the seasonally high water table or top of bedrock elevation by at least 1 m

|Designers should ensure that the bottom of the swale is separated from the seasonally high water table or top of bedrock elevation by at least 1 m.

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|Designers should consult local utility design guidance for the horizontal and vertical clearance between storm drains, ditches, and surface water bodies. It is feasible for on-site utilities to cross dry swales; however, |Dry swales typically treat drainage areas of less than two hectares. If dry swales are used to treat larger areas, the velocity through the swale becomes too great to treat runoff or prevent erosion. Typical ratios of impervious drainage area to dry swale area range from 5:1 to 15:1.

|Designers should consult local utility design guidance for the horizontal and vertical clearance between storm drains, ditches, and surface water bodies. It is feasible for on-site utilities to cross dry swales; however, |Dry swales typically treat drainage areas of less than two hectares. If dry swales are used to treat larger areas, the velocity through the swale becomes too great to treat runoff or prevent erosion. Typical ratios of impervious drainage area to dry swale area range from 5:1 to 15:1.

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Designers should ensure that the bottom of the swale is separated from the seasonally high water table or top of bedrock elevation by at least 1 m to prevent groundwater contamination

|Designers should ensure that the bottom of the swale is separated from the seasonally high water table or top of bedrock elevation by at least 1 m to prevent groundwater contamination.

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!Perforated Pipe

!Perforated pipe systems

|[[Perforated pipe systems]] should be located below shoulders of roadways, pervious boulevards or grass swales where they can be readily excavated for servicing. An adequate subsurface area outside of the 4 m setback from building foundations and suitable distance from other underground utilities must be available.

|[[Perforated pipe systems]] should be located below shoulders of roadways, pervious boulevards or grass swales where they can be readily excavated for servicing. An adequate subsurface area outside of the 4 m setback from building foundations and suitable distance from other underground utilities must be available.

|Systems cannot be located on natural slopes greater than 15 %. The gravel bed should be designed with gentle slopes between 0.5 - 1 %

|Systems cannot be located on natural slopes greater than 15 %. The gravel bed should be designed with gentle slopes between 0.5 - 1 %

|Systems typically receive foundation drain water and runoff from roofs, walkways, roads and parking lots from multiple lots. They are typically designed with an impervious drainage area to treatment facility area ratio of between 5:1 to 10:1

|Systems typically receive foundation drain water and runoff from roofs, walkways, roads and parking lots from multiple lots. They are typically designed with an impervious drainage area to treatment facility area ratio of between 5:1 to 10:1

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Facilities receiving road or parking lot runoff should not be located within 2 year time-of-travel wellhead protection areas.

|Designers should ensure that the bottom of the gravel bed is separated from the seasonally high water table or top of bedrock elevation by at least 1 m to prevent groundwater contamination

|Designers should ensure that the bottom of the gravel bed is separated from the seasonally high water table or top of bedrock elevation by at least 1 m to prevent groundwater contamination.

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!Green Roofs

!Green roofs

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!Rainwater Harvesting

!Rainwater harvesting

|Space limitations are rarely a concern with rainwater harvesting if considered during building design and site layout.

|Space limitations are rarely a concern with rainwater harvesting if considered during building design and site layout.

|Site topography influences the placement of storage tanks and the design of the rainwater conveyance and overflow systems.

|Site topography influences the placement of storage tanks and the design of the rainwater conveyance and overflow systems.

|The needed head depends on intended use of the water. For residential landscaping uses, the rain barrel or cistern should be sited upgradient of the landscaping areas or on a raised stand. Gravity-fed operations may also be used for indoor residential uses, such as laundry, that do not require high water pressure. For larger-scale landscaping operations, locating a cistern on the roof or uppermost floor may be the most cost efficient way to provide water pressure.

|The needed head depends on intended use of the water. For residential landscaping uses, the rain barrel or cistern should be sited upgradient of the landscaping areas or on a raised stand. Gravity-fed operations may also be used for indoor residential uses, such as laundry, that do not require high water pressure. For larger-scale landscaping operations, locating a cistern on the roof or uppermost floor may be the most cost efficient way to provide water pressure.

|Cisterns should be placed on or in native, rather than fill, soils. If placement on fill slopes is necessary, a geotechnical analysis is needed. Underground tanks and the pipes conveying rainwater to and from them, including overflow systems, should either be located below the local frost penetration depth (MTO, 2005), or insulated to prevent freezing during winter

|Cisterns should be placed on or in native, rather than fill, soils. If placement on fill slopes is necessary, a geotechnical analysis is needed. Underground tanks and the pipes conveying rainwater to and from them, including overflow systems, should either be located below the local frost penetration depth (MTO, 2005), or insulated to prevent freezing during winter

|Rainwater harvesting systems can be an effective stormwater BMP for roof runoff at sites where land uses or activities at groundlevel have the potential to generate highly contaminated runoff

|Rainwater harvesting systems can be an effective stormwater BMP for roof runoff at sites where land uses or activities at ground level have the potential to generate highly contaminated runoff

|Rainwater harvesting system overflow devices should be designed to avoid causing ponding or soil saturation within three 3 m of building foundations

|Rainwater harvesting system overflow devices should be designed to avoid causing ponding or soil saturation within three 3 m of building foundations

|The presence of underground utilities (e.g., water supply pipes, sanitary sewers, natural gas pipes, cable conduits, etc.), may constrain the location of underground rainwater storage tanks.

|The presence of underground utilities (e.g., water supply pipes, sanitary sewers, natural gas pipes, cable conduits, etc.), may constrain the location of underground rainwater storage tanks.