Changes

|-

|-

|

|

!Available Space

!Available space

!Site Topography

!Site topography

!Available Head

!Available Head

!Soils

!Soils

!Pollution Hot Spot Runoff

!Pollution hot spot runoff

!Setbacks from Buildings

!Setbacks from Buildings

!Proximity to Underground Utilities

!Proximity to underground utilities

!Drainage Area and Runoff Volume

!Drainage Area and runoff volume

!Wellhead Protection

!Wellhead protection

!Water Table

!Water table

!Overhead Wires

!Overhead wires

!Flow Path Length Across Impermeable Surface

!Flow path length across impervious catchment

!Winter Operations

![[Winter]] operations

|-

|-

!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 metres 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

|

|

|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 groundlevel 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

|

|

|

|

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

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

|

|

|

|

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

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

|

|

|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 four (4) metres from building foundations

|Facilities should be setback a minimum of 4 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

|Facilities receiving road or parking lot runoff should not be located within two (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

|The bottom of the facility should be vertically separated by one (1) metre from the seasonally high water table or top of bedrock elevation

|The bottom of the facility should be vertically separated by 1 m from the seasonally high water table or top of bedrock elevation

|

|

|

|

|-

|-

!Bioretention

!Bioretention

|Designers should reserve open areas of about 10 to 20% of the size of the contributing drainage area. These are areas that would be typically set aside for landscaping. More space is required for designs with soft and shallow side slopes than those with hard, vertical edges.

|Designers should reserve open areas of about 10 to 20 % of the size of the contributing drainage area. These are areas that would be typically set aside for [[landscaping]]. More space is required for designs with soft and shallow side slopes than those with hard, vertical edges.

|Bioretention is best applied when contributing slopes are between 1 to 5%. Ideally, the proposed treatment area will be located in a natural depression to minimize excavation

|Bioretention is best applied when contributing slopes are between 1 to 5%. Ideally, the proposed treatment area will be located in a natural depression to minimize excavation

|If an underdrain is used, then 1 to 1.5 metres elevation difference is needed between the inflow point and the downstream storm drain invert. This is generally not a constraint due to the standard depth of storm drains. For bioretention without an underdrain, the design will only require enough elevation difference to move large event flows through the overflow or bypass without generating a backflow or flooding problem.

|If an [[underdrain]] is used, then 1 to 1.5 m elevation difference is needed between the inflow point and the downstream storm drain invert. This is generally not a constraint due to the standard depth of storm drains. For bioretention without an underdrain, the design will only require enough elevation difference to move large event flows through the [[overflow]] or bypass without generating a backflow or flooding problem.

|Bioretention can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balance benefits. Facilities should be located in portions of the site with the highest native soil infiltration rates. Where infiltration rates are less than 15 mm/hr (hydraulic conductivity less than 1 x 10^-6 cm/s) an underdrain is required.

|Bioretention can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balance benefits. Facilities should be located in portions of the site with the highest native soil infiltration rates. Where infiltration rates are less than 15 mm/hr an underdrain is required.

|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 bioretention facilities designed for full or partial infiltration. Facilities designed with an impermeable liner (filtration only facilities) can be used to treat runoff from pollution hot spots

|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 bioretention facilities designed for full or partial infiltration. Facilities designed with an impermeable [[liner]] (i.e.[[stormwater planters]]) can be used to treat runoff from pollution hot spots

|If an impermeable liner is used, no setback is needed. If not, a four (4) metre 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 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.

|Facilities receiving road or parking lot runoff should not be located within two (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 one (1) metre 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.

|Designers should also check whether maximum future tree canopy height in the bioretention area will not interfere with existing overhead phone and power lines.

|Designers should also check whether maximum future tree canopy height in the bioretention area will not interfere with existing overhead phone and power lines.

|

|

|-

|-

!Vegetated Filter Strips

!Vegetated Filter Strips

|The flow path length across the vegetated filter strip should be at least 5 metres to provide substantial water quality benefits (Barrett et al., 2004). Vegetated filter strips incorporated as pretreatment to another water quality best management practice may be designed with shorter flow path lengths.

|The flow path length across the vegetated [[filter strip]] should be at least 5 m to provide substantial water quality benefits (Barrett et al., 2004). Vegetated filter strips incorporated as pretreatment to another water quality best management practice may be designed with shorter flow path lengths.

|Filter strips are best used to treat runoff from ground-level impervious surfaces that generate sheet flow (e.g., roads and parking areas). The recommended filter strip slope is between 1% to 5%

|Filter strips are best used to treat runoff from ground-level impervious surfaces that generate sheet flow (e.g., roads and parking areas). The recommended filter strip slope is between 1 % to 5 %

|

|

|Filter strips are a suitable practice on all soil types. If soils are highly compacted, or of such low fertility that vegetation cannot become established, they should be tilled to a depth of 300 mm and amended with compost to achieve an organic content of 8 to 15% by weight or 30 to 40% by volume

|Filter strips are a suitable practice on all soil types. If soils are highly compacted, or of such low fertility that vegetation cannot become established, they should be tilled to a depth of 300 mm and amended with compost to achieve an organic content of 8 to 15 % by weight or 30 to 40 % by volume

|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 vegetated filter strips.

|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 vegetated filter strips.

|

|

|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.

|Local utility design guidance should be consulted to define the horizontal and vertical offsets. Generally, requirements for underground utilities passing under or near permeable pavement will be no different than for utilities in other pervious areas. However, permeable pavement has a deeper base than conventional pavement which may impact shallow utilities.

|Local utility design guidance should be consulted to define the horizontal and vertical offsets. Generally, requirements for underground utilities passing under or near permeable pavement will be no different than for utilities in other pervious areas. However, permeable pavement has a deeper base than conventional pavement which may impact shallow utilities.

|In general, the impervious area treated should not exceed 1.2 times the area of permeable pavement which receives the runoff

|In general, the impervious area treated should not exceed 1.2 times the area of permeable pavement which receives the runoff.

|Permeable pavement should not be used for road or parking surfaces within 2 year time-of-travel wellhead protection areas

|Permeable pavement should not be used for road or parking surfaces within 2 year time-of-travel wellhead protection areas.

|The base of permeable pavement stone reservoir should be at least 1 m above the seasonally high water table or bedrock elevation.

|The base of permeable pavement stone reservoir should be at least 1 m above the seasonally high water table or bedrock elevation.

|

|

|

|

|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 salts 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 [[de-icing]] salt applied sparingly

|-

|-

!Enhanced Swales

!Enhanced Swales

|Grass [[swales]] usually consume about 5 to 15 percent of their contributing drainage area. A width of at least 2 metres 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 and 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

|

|

|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 four (4) metres 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 centerline 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.

|-

|-

!Bioswales

!Bioswales

|[[Dry swale]] footprints are approximately 5 to 15% of their contributing drainage area. When applied to residential areas, the swale segments between driveways should be at least 5 metres in length.

|[[Dry swale]] footprints are approximately 5 to 15 % of their contributing drainage area. When applied to residential areas, the swale segments between driveways should be at least 5 m in length.

|Dry swales should be designed with longitudinal slopes generally ranging from 0.5 to 4%, and no greater than 6% (PDEP, 2006). On slopes steeper than 3%, check dams should be used.

|Dry swales should be designed with longitudinal slopes generally ranging from 0.5 to 4%, and no greater than 6 % (PDEP, 2006). On slopes steeper than 3%, check dams should be used.

|

|

|Dry swales can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balance benefits. Facilities should be located in portions of the site with the highest native soil infiltration rates. Where infiltration rates are less than 15 mm/hr, an underdrain is required

|Dry swales can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balance benefits. Facilities should be located in portions of the site with the highest native soil infiltration rates. Where infiltration rates are less than 15 mm/hr, an underdrain is required

|-

|-

!Perforated Pipe

!Perforated Pipe

|[[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 four (4) metre 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 to 1%

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

|

|

|Underlying native soil conditions do not constrain the use of perforated pipe systems but greatly influence their runoff reduction performance

|Underlying native soil conditions do not constrain the use of perforated pipe systems but greatly influence their runoff reduction performance

|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 perforated pipe systems.

|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 perforated pipe systems.

|Facilities should be setback a minimum of four (4) metres from building foundations.

|Facilities should be setback a minimum of four 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

|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 two (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

|

|

|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 groundlevel 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) metres 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.

|

|