LID opportunities in road-right-of-ways

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Rights of way (RoW) standards in Ontario vary by municipality, but generally there are seven typical ROW types:

This article discusses the characteristics, opportunities, constraints, and examples for each of these road types. This guidance is not intended to be prohibitive of other 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. options, but rather to help reduce the number of 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. options in the preliminary phases of screening and to alert the designer to 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. opportunities unique to each road type. Adjacent land uses, traffic demands, utility locations, budget constraints and geological conditions will determine the most appropriate 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. solution.

Local residential road

Residential Road (Rural Cross-Section) and applicable 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. options

Local residential streets are the most common street type. They serve as access to the residential lots within areas created by, or bounded by, thoroughfares, arterials, collectors, primary residential streets and other physical boundaries, e.g. natural streams and railroads. Since their primary function is local vehicular access rather than inter-community circulation, theses roads have low traffic volumes and serve mostly lightweight vehicular traffic, but they must accommodate the rapid access needs of emergency vehicles.

Rural cross-section

Characteristics specific to the residential rural cross section include:

  • Shoulders are grassed, gravel, or bare soil from winter maintenance, pedestrians and street side parking
  • Side drainage ditches are often narrow, poorly graded,and can be difficult for homeowners to maintain
  • Utilities are often in separate trenches rather than a combined utility trench
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. options for rural residential road (rural cross section)
(** = Common, * = Possible, o = Unusual)
RoW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving Prefabricated modules
Resurfacing o o * ** ** * * o
Reconstruction o o * ** ** * * o

Opportunities for rural residential

Within the roadway Within the boulevard
  • Use of permeable paving within the roadway is not economical when there are adjacent swales to filter and infiltrate 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.
  • Bioswales or the use of perforated pipes beneath grass swalesVegetated, 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 reduce the nuisance problems associated with conventional 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. like standing surface water and steep slopes
  • 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. systems can be used to stabilize and improve degraded shoulders
  • Converting degraded ditches to enhanced grass swales is the simplest 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. improvement for residential rural cross-section roads. Driveway culverts can be slightly raised to provide storage and encourage infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface..

Urban cross-section

Local residential road (urban cross-section) and applicable 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. options

Characteristics specific to the urban cross section include:

  • Parking zones are often underused
  • Residential boulevard space is the easiest to modify and use for stormwater management compared to other street types
  • Utility lines may be in separate or shared trenches
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. options for local residential road (urban cross section)
(** = Common, * = Possible, o = Unusual)
RoW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswale Enhanced swales Exfiltration trenches Permeable paving (sidewalk) Prefabricated modules
Rural to Urban Reconstruction o * ** * * ** ** o
Resurfacing o ** ** * * ** * o
Reconstruction o ** ** * * ** ** o
Reduction o * ** * * ** o o

Opportunities for urban residential

Within the roadway Within the boulevard
  • Curb extensions are a good method for calming traffic and using underutilized parking zones
  • Due to low speeds and low traffic, 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. can be used from curb to curb
  • Boulevard bioretention can be easily incorporated into a rural-to-urban upgrade by allowing for stormwater treatment within the boulevard space

Residential collector roadA road on which traffic movement and access to property have similar importance.

Cross section of a residential collector roadA road on which traffic movement and access to property have similar importance.

These streets act as connectors between residential neighborhoods and other collectors and arterials. The character of these streets can vary widely, from completely residential to mixed-use to commercial.

Characteristics include:

  • Moderate to high traffic volumes, average daily traffic 1500 to 3000 vehicles
  • Street parking is atypical unless there are adjacent mixed use areas
  • Often have multi-modal use: transit, pedestrian, cyclists
  • Institutions such as schools, recreational facilities, and churches are often located along collectors
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. options for residential collector roadA road on which traffic movement and access to property have similar importance.
(** = Common, * = Possible, o = Unusual)
RoW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving (sidewalk) Prefabricated modules
Rural Resurfacing o o ** ** ** * * o
Rural Reconstruction o o ** ** ** * * o
Rural to Urban Reconstruction o * ** ** o ** ** *
Urban Resurfacing o o ** * o * ** *
Urban Reconstruction o * ** * o ** ** *
Urban Reduction o o ** * o ** o *

Opportunities for residential collector cross section

Within the roadway Within the boulevard
  • Permeable paving is an option for parking lanes and sidewalk. However, permeable pavers are susceptible to clogging if receiving 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. drainage from adjoining asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. roadway. Avoid 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. for high traffic travel lanes. Pervious concrete or porous asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. are options for bike lanes.
  • Perforated pipes are suitable for collectors with very limited space, particularly where there is no routine landscaping maintenance. However, adequate 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. such as grass swalesVegetated, 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., extended sump catchbasins, or prefabricated units must be provided.
  • Curb extension bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. is not a common practice for collectors, but they can be used in some cases to reduce pedestrian crossing distances at intersections
  • Collectors with few driveway access points and continuous stretches of open boulevard space are good candidates for 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.
  • Institutional uses along collectors offer opportunities for innovative 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. solutions. 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. can be treated within adjacent park space or on school properties where agreements have been made with school boards. These areas are also good opportunities for 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. showcases or demonstrations.

Local industrial road

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. options for the local industrial road

Local industrial roads provide access to industry and other employment zones. Providing access and easy movement for large vehicles are a primary design characteristic of these types of streets. They have two-to-three lanes and are not intended for through traffic.

Characteristics include:

  • Traffic volumes may be low, but the road must still be wide enough to accommodate large vehicle turning movements and have the structural strength to support heavy loads
  • To avoid interference with truck movements, landscaping should be low, and trees should be high branching or setback from the roadway
  • Boulevards are often wide, allowing for 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. or other landscape treatment options
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. options local industrial road
(** = Common, * = Possible, o = Unusual)
RoW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving (sidewalk) Prefabricated modules
Rural Resurfacing o o * * ** * * *
Rural Reconstruction o o * * ** * * *
Rural to Urban Reconstruction o o * * o ** ** **
Urban Resurfacing o o * * o * * **
Urban Reconstruction o o * * o ** ** **
Urban Reduction o o * * o ** * **

Opportunities for local industrial cross section

Within the roadway Within the boulevard
  • Consideration should be given for wide turning trucks which may encroach on and degrade landscaping or road shoulders. Use grid paver systems or widened gravel shoulders near turning areas to accommodate occasional encroachment.
  • 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. options for local industrial roads depend heavily on adjacent industries. For example, 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. and other filtering practices may clog quickly where heavy industry like concrete mixing plants track sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. onto the roads.
  • Grass swalesVegetated, 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. with sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. traps or prefabricated oil/grit separators which can be cleaned out on a frequent routine basis would be appropriate.
  • 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. and perforated pipe can work well in areas of light industrial and commercial land uses.

Industrial collector roadA road on which traffic movement and access to property have similar importance.

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. options for the industrial collector roadA road on which traffic movement and access to property have similar importance.

The function of industrial collectors is to provide efficient traffic flow, accomodation for large transport vehicles and access to industry and other employment land areas. These roads are typically four to five lanes and have wide boulevards. Other characteristics include:

  • High profile industry is often located along industrial collectors and a high quality corporate landscape treatment is expected
  • To avoid interference with truck movements landscaping near roads should be low and trees should be high branching or setback from the roadway
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. options industrial collector roadA road on which traffic movement and access to property have similar importance.
(** = Common, * = Possible, o = Unusual)
RoW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving Prefabricated modules
Rural Resurfacing o o * * ** * * *
Rural Reconstruction o o * * ** * * *
Rural to Urban Reconstruction o o * * * ** * **
Urban Resurfacing o o * * * * * **
Urban Reconstruction o o * * * ** * **
Urban Reduction o o * * * ** * **

Typical 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. opportunities

Within the roadway:

  • Due to high traffic and heavy vehicles, 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. options within the roadway are limited. Prefabricated sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. traps and perforated pipe with proper 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. are potential options.

Within the boulevard:

  • Broad enhanced grass swalesVegetated, 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. with perforated pipe can take advantage of wide boulevard spaces
  • Any landscape-based solutions must consider the landscaping expectations of adjacent properties, with respect to both aesthetics and maintenance. Some areas will expect simple turf lawn frontage that can be easily maintained, while other higher-profile industrial

areas will want distinctive, signature landscapes with decorative plantings and shrubs.

Minor arterial

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. options for the minor arterial roadA road primarily for through traffic.

Minor arterial roads are automobile-oriented, move high volumes ofvehicle traffic and are typically four lanes. Pedestrian and bicyclist accommodations are sometimes expected. Other common characteristics include:

  • Boulevards are often wide, but must accommodate street trees, splash pads and sidewalks on both sides
  • May include narrow medians, but 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 typically directed away from them to road sides
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. options for the minor arterial roadA road primarily for through traffic.
(** = Common, * = Possible, o = Unusual)
ROW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving Prefabricated modules
Rural Resurfacing o o * * ** * * *
Rural Reconstruction o o * * ** * * *
Rural to Urban Reconstruction ** o * * o ** ** **
Urban Resurfacing o o * * o * * **
Urban Reconstruction ** o * * o ** ** **
Urban Reduction ** o * * o ** * **

Typical 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. opportunities

Within the roadway:

  • Dedicated parking lanes or parking lay-bys can be converted to permeable pavers. The permeable parking lane can be designed to accept only the rainfall that falls on it or it can take 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 up to two additional lanes.

Within the boulevard:

  • Attractive stormwater planters and permeable paving sidewalks are appropriate for high density areas and where business districts expect an enhanced or signature streetscape.
  • Street trees can be supported with 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. options by providing root volume space in bioretention practices or with sidewalk support systems. Permeable sidewalks allow air and moisture to reach tree roots, which in turn reduces sidewalk buckling from roots pushing through the surface.

Major arterial roadA road primarily for through traffic.

text

Major Arterials are broad, four to six lanes, with an emphasis on speed, high volume vehicle flow and little on pedestrian or bicycle accommodation. Other characteristics include:

  • Wide boulevards and large landscaped medians are common
  • Due to higher travel speeds, maintaining clear zones and sight distances is critical
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. options for the major arterial roadA road primarily for through traffic.
(** = Common, * = Possible, o = Unusual)
ROW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving Prefabricated modules
Rural Resurfacing o o * * ** * * *
Rural Reconstruction o o * * ** * * *
Rural to Urban Reconstruction o o * * o ** ** **
Urban Resurfacing o o * * o * * **
Urban Reconstruction ** o * * o ** ** **
Urban Reduction ** o * * o ** * **

Typical 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. opportunities

Within the roadway:

  • Where possible, replace unnecessarily paved areas such as medians or traffic islands with pervious areas. If road grading allows, convert these areas into treatment practices for surrounding imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. areas
  • If the road is double crowned, medians are an excellent place to treat arterial 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. with simply landscaped bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. areas or 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.
  • If road grades direct no 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. to the median, reducing the median width and increasing the boulevard space would open more area for stormwater treatment along the side of the roads where 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. drains
  • Getting plants to survive may be difficult in narrow medians. Consider decorative permeable paver solution over simply covering them with imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. or concrete

Within the boulevard:

  • BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. planters are appropriate for high profile urban arterial roads, but they must be properly designed to handle flows from larger imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. areas and have easily cleaned 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. practices

Main streets

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. options for main streets

Main streets are set in areas with high-density commercial, residential, and mixed use and are typically focal points of the community. The buildings have small to no setbacks and create a continuous wall along the street. They offer an opportunity to incorporate beautifying green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics., but they are also a challenge for designers owing to the multiple demands of street parking, street trees, business access, above and below ground utilities, pedestrian accommodations and vehicle movement. Depending on age and prominence, these streets may have been reconstructed multiple times and have infrastructure legacy issues like abandoned utility lines. Other characteristics include:

  • Street parking is typical, may have frequent turn over and is necessary for local business.
  • ROW dimensions will vary greatly depending on the age of the community.
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. options for main streets
(** = Common, * = Possible, o = Unusual)
ROW Construction Type Stormwater planters Curb extensions Boulevard bioretention Bioswales Enhanced swales Exfiltration trenches Permeable paving Prefabricated modules
Urban Resurfacing o o o o o o * **
Urban Reconstruction ** ** o o o ** ** **
Urban Reduction ** ** o o o ** ** **

Typical 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. opportunities

Multifunctional 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. practices are favored where there is a premium on space. BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. planters can serve to beautify the street and to treat stormwaterSurface runoff from at-grade surfaces, resulting from rain or snowmelt events.. 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. serves as a treatment practice but is also a hardscape for parking and pedestrians.

Within the roadway:

  • Curb extension bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. can be used as a traffic calming feature and reduce pedestrian crossing distances.

Within the boulevard:

  • Due to the high profile of these types of street, they are maintained on a frequent basis and provide the most appropriate setting for aesthetically pleasing bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. features.
  • Street trees are high priorities for this road type and 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. options should support or incorporate them by providing root volume space in bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. practices or with sidewalk support systems.

Other design considerations

The previous sections presented the most common options based on road and construction types. The project team must use the information gathered through the background review and field reconnaissance, feedback gained from the public engagement, as well as from the 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 Suitability & Considerations Comparison Table to determine the feasible and optimal 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. options for the site. Below is a list of factors to be considered when choosing the type of practice and how it will be incorporated into the site:

Relevant stormwater criteria – compliance with high level municipal and agency documents (i.e. Subwatershed study, master drainage plan).

Site users – who are the users and how will they use the site in future (i.e. are pedestrians using this street to access other services such multi-use pathways, bus routes, commercial areas).

Surrounding land use – schools, community centers, industrial, residential or commercial areas.

Project support – are the local users likely to support the initiatives and become engaged in the project (renters vs. property owners).

Mature vegetation – large trees can be a constraint particularly in municipalities with tree protection bylaws.

Underground and overhead utilities – utility conflicts may eliminate an 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. option but there are workaround solutions

Accommodation of surface elements – location, sizing, and spacing of 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. practices must consider surface elements such as light standard, transit shelters and fire hydrants. The structural support of these also must be considered, for example a light standard near bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. may require a deeper base.

Current or future transportation requirements - transportation planning initiatives can be integrate into the ROW retrofit design objectives to facilitate future projects.

Existing aesthetic character of the site – neighborhoods with established gardens, mature trees, and professionally landscaped frontages may be more receptive to a higher landscape aesthetic of vegetated 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. practices such as bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. or 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..

Existing maintenance protocols and equipment – how is the ROW currently maintained and can the same techniques be used after the 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 is constructed.

Impacts to local drinking water wells – consider if threats under Source Water Management Plans have been identified.

Encroachment issues (residents encroaching within the ROW) – including fences, driveways, or other structures

Traffic safety issues – are there reports or records of increased traffic issues. If so consider how the 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 can be used to address the issues.

Parking availability and access – where parking must be preserved, 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 considered, but where parking is underused, then imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. area can be reduced with curb extensions or reduced street width.

Additional benefit opportunities – are there other retrofit opportunities that can be incorporated into the retrofit such as park improvements, trail connections and educational signage potential.

Existing municipal policies and by-laws – The existing policies and by-laws review should not be considered as barriers to the project, but instead should be considered in the context of points of discussion for the municipal project team during the implementation process. Undertaken in the context of a demonstration project, the existing by-laws and standards can be relaxed and reviewed within a controlled environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.. With all the departments leads present, a demonstration project can be an opportune time to discuss and re-evaluate. Typical municipal codes, standards and bylaws to be investigated may include:

  • Noxious weed by-laws – can exclude native species and limit plant selection. Redefinition and re-evaluation of plants within these lists may be warranted.
  • Property standards by-laws – can prevent implementation of 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. practices such as permeable pavements (gravel or turf stone driveways), bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. or 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. which incorporate temporary surface ponding.
  • Boulevard planting by-laws – can prevent implementation of 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. practices such as 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. due to plant type and height restrictions of planting along municipal ROW and boulevards.
  • Standing waterWater ponded on the ground surface. by-laws – can prevent implementation of 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. practices which incorporate temporary surface storage. The definition (or redefinition) of ‘standing waterWater ponded on the ground surface.’ to allow for up to 48 hours of ponded water within 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. practices may be warranted.

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