Difference between revisions of "Structural practices summary"

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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 [[Salt management|de-icing salt]] applied sparingly.
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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 [[Salt management|de-icing salt]] applied sparingly.
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Also, plowed snow should not be stored on top of permeable pavements, since this snow often contains granular materials which can contribute to clogging.
 
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!Enhanced swales
 
!Enhanced swales

Revision as of 18:18, 15 January 2019

LIDLow 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. Design Guide Detail
Available space Site topography Available head Soils Pollution hot spotAreas where certain land uses or activities have the potential to generate highly contaminated runoff (e.g., vehicle fuelling, service or demolition areas, outdoor storage and handling areas for hazardous materials and some heavy industry sites). runoffThat potion of the water precipitated onto a catchment area, which 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. Setbacks from buildings Proximity to underground utilities Drainage areaThe 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. and runoffThat potion of the water precipitated onto a catchment area, which 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. volume Wellhead protection Water tableThe 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. Overhead wires Flow path lengthThe minimum linear distance of water flow across a surface. across imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale. Winter operations
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 LIDLow 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. practice such as a rainwater harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. system, soakawayAn 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., swaleA 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., bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. area or perforated pipe system. Disconnected downspouts should discharge to a gradual slope that conveys runoffThat potion of the water precipitated onto a catchment area, which 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. away from the building. The slope should be between 1% and 5%. Grading should discourage flow from reconnecting with adjacent imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces. If the infiltration rateThe rate at which stormwater percolates into the subsoil measured in inches per hour. 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 compostDecayed 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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. as long as the roof runoffThat potion of the water precipitated onto a catchment area, which 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. is kept separate from runoffThat potion of the water precipitated onto a catchment area, which 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. from ground level imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces. For simple downspout disconnection the roof drainage areaThe 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. should not be greater than 100 m2.
Soakaways, Infiltration Trenches and Chambers 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 balanceThe accounting of inflow and outflow of water in a system according to the components of the hydrologic cycle. and channel erosion controlIncludes the protection of soil from dislocation by water, wind or other agents. objectives. If possible, facilities should be located in portions of the site with the highest native soilThe natural ground material characteristic of or existing by virtue of geographic origin. infiltration rates. To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by soakaways, infiltration trenches or chambers. 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 They can be designed with an imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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. Facilities receiving road or parking lot runoffThat potion of the water precipitated onto a catchment area, which 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. should not be located within 2 year time-of-travel wellhead protection areas The bottom of the facility should be vertically separated by 1 m from the seasonally high water tableThe 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. or top of bedrock elevation
BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. Designers should reserve open areas of about 10 to 20 % of the size of the contributing drainage areaThe 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.. 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. BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. 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 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 bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. without an underdrainA perforated pipe used to assist the draining of soils., 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. BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balanceThe accounting of inflow and outflow of water in a system according to the components of the hydrologic cycle. benefits. Facilities should be located in portions of the site with the highest native soilThe natural ground material characteristic of or existing by virtue of geographic origin. infiltration rates. Where infiltration rates are less than 15 mm/hr an underdrainA perforated pipe used to assist the draining of soils. is required. To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. facilities designed for full or partial infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.. Facilities designed with an impermeable liner (i.e.stormwater planters) can be used to treat runoffThat potion of the water precipitated onto a catchment area, which 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. from pollution hot spots 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 bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.; 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 BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. 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 areaThe 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. to one bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. facility is approximately 0.8 Ha (Davis et al., 2009). Ideally, bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. should be used as a source controlA practice or structural measure that is usually implemented at the beginning of a drainage system or at the lot level, to reduce the volume of runoff and minimize the concentration of pollution in overland flow from private property and prevent pollutants from entering Stormwater runoff or other environmental media, as described by the Ministry of Environment. for small drainage areas and not as an end of pipe control. Typical ratios of imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe 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. to bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. cell area range from 5:1 to 15:1. Facilities receiving road or parking lot runoffThat potion of the water precipitated onto a catchment area, which 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. should not be located within 2 year time-of-travel wellhead protection areas. BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. should be separated from the seasonally high water tableThe 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. 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 bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. area will not interfere with existing overhead phone and power lines.
Vegetated Filter Strips 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 pretreatmentInitial capturing and removal of unwanted contaminants, such as debris, sediment, leaves and pollutants, from stormwater before reaching a best management practice; Examples include, settling forebays, vegetated filter strips and gravel diaphragms. to another water quality best management practice may be designed with shorter flow path lengths. Filter strips are best used to treat runoffThat potion of the water precipitated onto a catchment area, which 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. from ground-level imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces that generate sheet flow (e.g., roads and parking areas). The recommended filter stripa 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. 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 compostDecayed 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by vegetated filter strips. Filter strips should only be used where depth to the seasonally high water tableThe 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. is at least 1 m below the surface. A limiting design factor is that the maximum flow path length across the impermeable surface should be less than 25 m.
Permeable pavementAn 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. The slope of the permeable pavementAn 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. surface should be at least one percent and no greater than five percent. The imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. land surrounding and draining into the pavement should not exceed 20 % slope. Systems located in low permeability soils with an infiltration rateThe rate at which stormwater percolates into the subsoil measured in inches per hour. of less than 15 mm/hr, require incorporation of a perforated pipe underdrainA perforated pipe used to assist the draining of soils.. To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by permeable pavementAn 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. Permeable pavementAn 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. should be located downslope from building foundations. If the pavement does not receive runoffThat potion of the water precipitated onto a catchment area, which 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. 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 pavementAn 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. will be no different than for utilities in other pervious areas. However, permeable pavementAn 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. has a deeper base than conventional pavement which may impact shallow utilities. In general, the imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. area treated should not exceed 1.2 times the area of permeable pavementAn 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. which receives the runoffThat potion of the water precipitated onto a catchment area, which 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.. Permeable pavementAn 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. should not be used for road or parking surfaces within 2 year time-of-travel wellhead protection areas. The base of permeable pavementAn 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. stone reservoirAn underlying bed filled with aggregate or other void-forming fill material that temporarily stores stormwater before infiltrating into the native soil or being conveyed by an underdrain pipe. should be at least 1 m above the seasonally high water tableThe 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. or bedrock elevation. SandMineral 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. or other granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. 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.

Also, plowed snow should not be stored on top of permeable pavements, since this snow often contains granularGravel, or crushed stone of various size gradations (i.e., diameter), used in construction; void forming material used as bedding and runoff storage reservoirs and underdrains in stormwater infiltration practices. materials which can contribute to clogging.

Enhanced swalesA 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. Grass swales usually consume about 5 - 15 % of their contributing drainage areaThe 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 width of at least 2 m is needed. Site topography constrains the application of grass swalesA 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.. Longitudinal slopes between 0.5 - 6% are allowable. This prevents ponding while providing residence time and preventing erosion(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).. On slopes steeper than 3%, check dams should be used. Grass swalesA 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by grass swalesA 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.. Enhanced grass swalesA 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. should be located a minimum of 4 m from building foundations to prevent water damage. Utilities running parallel to the grass swaleA 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. should be offset from the centre line of the swaleA 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.. Underground utilities below the bottom of the swaleA 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. are not a problem. The conveyance capacity should match the drainage areaThe 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.. Sheet flow to the grass swaleA 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. is preferable. If drainage areas are greater than 2 hectares, high discharge through the swaleA 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. may not allow for filtering and infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface., and may create erosive conditions. Typical ratios of imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe 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. to swaleA 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. area range from 5:1 to 10:1. Designers should ensure that the bottom of the swaleA 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. is separated from the seasonally high water tableThe 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. or top of bedrock elevation by at least 1 m.
BioswalesLinear 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. Dry swale footprints are approximately 5 to 15 % of their contributing drainage areaThe 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.. When applied to residential areas, the swaleA 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. segments between driveways should be at least 5 m in length. Dry swalesLinear 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. 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 damsStructures 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. should be used. Dry swalesLinear 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. can be located over any soil type, but hydrologic soil group A and B soils are best for achieving water balanceThe accounting of inflow and outflow of water in a system according to the components of the hydrologic cycle. benefits. Facilities should be located in portions of the site with the highest native soilThe natural ground material characteristic of or existing by virtue of geographic origin. infiltration rates. Where infiltration rates are less than 15 mm/hr, an underdrainA perforated pipe used to assist the draining of soils. is required To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated dry swalesLinear 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. designed for full or partial infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface.. Facilities designed with an impermeable liner can be used to treat runoffThat potion of the water precipitated onto a catchment area, which 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. from pollution hot spots Dry swalesLinear 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. should be setback four 4 m from building foundations. When located within 3 metres of building foundations, an impermeable liner and perforated pipe underdrainA perforated pipe used to assist the draining of soils. system should be used. Dry swalesLinear 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. typically treat drainage areas of less than two hectares. If dry swalesLinear 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. are used to treat larger areas, the velocity through the swaleA 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. becomes too great to treat runoffThat potion of the water precipitated onto a catchment area, which 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. or prevent erosion(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).. Typical ratios of imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe 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. to dry swaleLinear 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. area range from 5:1 to 15:1. Facilities receiving road or parking lot runoffThat potion of the water precipitated onto a catchment area, which 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. should not be located within 2 year time-of-travel wellhead protection areas. Designers should ensure that the bottom of the swaleA 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. is separated from the seasonally high water tableThe 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. or top of bedrock elevation by at least 1 m to prevent groundwater contamination.
Perforated pipe systems Perforated pipe systems should be located below shoulders of roadways, pervious boulevards or grass swalesA 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. 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 % Underlying native soilThe natural ground material characteristic of or existing by virtue of geographic origin. conditions do not constrain the use of perforated pipe systems but greatly influence their runoffThat potion of the water precipitated onto a catchment area, which 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. reduction performance To protect groundwater from possible contamination, source areas where land uses or human activities have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. should not be treated by perforated pipe systems. 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 Systems typically receive foundation drain water and runoffThat potion of the water precipitated onto a catchment area, which 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. from roofs, walkways, roads and parking lots from multiple lots. They are typically designed with an imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. drainage areaThe 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. to treatment facility area ratio of between 5:1 to 10:1 Facilities receiving road or parking lot runoffThat potion of the water precipitated onto a catchment area, which 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. 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 tableThe 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. or top of bedrock elevation by at least 1 m to prevent groundwater contamination.
Green roofs Green roofs are designed to capture precipitationAny form of rain or snow. falling directly onto the roof surface. They are not designed to receive runoffThat potion of the water precipitated onto a catchment area, which 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. diverted from other source areas.
Rainwater harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. Space limitations are rarely a concern with rainwater harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. 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. The needed head depends on intended use of the water. For residential landscaping uses, the rain barrel or cisternTank used to store rainwater (typically roof runoff) for later use. 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 cisternTank used to store rainwater (typically roof runoff) for later use. on the roof or uppermost floor may be the most cost efficient way to provide water pressure. CisternsTank used to store rainwater (typically roof runoff) for later use. 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 harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. systems can be an effective stormwater BMPBest 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. for roof runoffThat potion of the water precipitated onto a catchment area, which 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. at sites where land uses or activities at ground level have the potential to generate highly contaminated runoffThat potion of the water precipitated onto a catchment area, which 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. Rainwater harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. 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.