Drawings

Overview

Whilst we consider preparing our own set of STEP LID drawings, we are providing a quick reference list to drawing files from other Ontario and/or North American-based sources.

If you want help in finding example details for an LID design, please email the Wiki Guide email account or use the comment box below.

You know that typical drawings are no substitute for properly configured design!

Ontario Municipal References

• The City of Toronto Green Streets program included production of many drawn 'typicals'. See example of curb extensions to the right.
• The Toronto, Construction Specifications and Drawings for Green Infrastructure program included production of many LID drawings' cross sections. See some examples below.
• The City of Kitchener has standard details for pervious concrete pavement, precast permeable interlocking pavement and permeable pipe exfiltration systems, a note - you will have to send them an email requesting access to their development manual.
• The City of Barrie has a draft standard detail for an exfiltration trench and soakaway pit in Appendix A - Figures of the linked website. Note that the 'within-WHPA' detail is not supported by STEP.
• The City of Cambridge's, Stormwater Management Policies and Guidelines show typical cross section drawings for dry ponds, constructed wetlands, bioretention, etc..

Exfiltration Systems

Please see below a Profile view of an exfiltration system (or perforated pipe system) designed for use in the City of Barrie and used in conjunction with a typical storm sewer system. Note: This cross section installment is 'not located within a WHPA', although the source document for this drawing showcases a similar design configuration, that is 'located within a WHPA', which is not supported by STEP.

Drawings are from the City of Barrie's, Drainage Master Plan document. For further details about these cross section drawings please visit the link.

Infiltration Trenches, Chambers & Soakaways

Please see below a profile and plan view of an infiltration trench designed to treat and temporarily store stormwater for use in the City of Toronto located within the laneway between the road and sidewalk in a heavily urbanized location. This drawing depicts the use of an underdrain in the system where remaining stormwater runoff is directed to the nearby storm sewer system.

Drawings are from the City of Toronto's, Design Criteria for Green Infrastructure in the Right-of-Way document. For further details about these cross section drawings please visit the link.

Please see below a profile view of an infiltration chamber installed below a parking lot in a shopping centre development in Brampton, Ontario. The stormwater chamber system receives roof, road and parking lot runoff from a large drainage area that then drains to a receiving waterbody. The system was designed to provide temporary storage and controlled release of runoff from storms to minimize impacts to the receiving waterbody (elevated water temperatures, higher velocity flows, potential for elevated flood conditions, etc.). A 0.3m deep gravel bed with no outlet below a portion of the chamber area provides additional water storage in the event of a large or prolonged storm/rainfall event to provide better retention of sediment and the means to evaluate whether or not substantial infiltration occurs. Orifice flow restricting plates mounted on the outlets of each manhole cause stormwater to back up into the chambers and contributing storm sewers so that when flow into the manhole exceeds the maximum flow rate of the orifice plate, stormwater backs up into the chambers safely.

Drawings are from STEP's, Technical Brief - Evaluation of Underground Stormwater Infiltration Systems document. The drawing was adapted from Counterpoint Engineering - Bramport Commercial Development, City of Brampton, Airport Road and Bovaird Drive – Site Servicing Plan Drawing No. SW-S1. Project No. 04160. May 7, 2007. Vaughan, ON. For further details about this cross section drawing please visit the link.

Please see below a profile and plan view of a soakaway (also known as a dry well) installed on a residential property connected to the home's downspout. The drawing depicts how the installation can be installed with a typical downspout disconnection (or bypass), and fitted with an overflow that connects to the home's stormwater lateral that then enters the municipal system. This configuration of a soakway allows for full infiltration and includes an inspection port for monitoring purposes.

Drawings are from the New Jersey Department of Environmental Protection's NJ Stormwater Best Management Practices Manual. . For further details about this cross section drawing and other LID BMPs please visit the link.

Bioretention

Please see below a profile and plan view (along with a larger scale intersection plan view) of a bioretention facility designed in an urban curb extension/"bump-out" designed to both calm traffic, enhance green space in an urban setting and treat overflow/runoff from the nearby street. Given that the bioretention installation is bound entirely with impermeable hardscape there is limited options for pretreatment. In the cross-sections shown below the pretreatments included in the installation are the inclusion of sediment traps sediment traps - a type of forebay, which dissipate incoming flow into the feature and causes suspended sediment to settle out of the water. This allows for accumulated sediment to be cleaned out during general maintenance of the bioretention feature.

An excellent opportunity for integrating more bioretention into the street is through careful design of curb extensions for traffic control . See Roadside safety for design advice specific to this application. This drawing also depicts partial exfiltration with an installed underdrain as soils in this feature possess infiltration rates lower than 15mm/hr, and possesses several plantings. Remaining stormwater runoff is directed to the nearby storm sewer system.

Drawings are from the City of Toronto's, Design Criteria for Green Infrastructure in the Right-of-Way document. For further details about these cross section drawings please visit the link.

Green Roof

Please see below a profile view of a standard extensive green roof with a stone buffer layer, growing medium, filter layer, drainage layer, root barrier/protection layer, waterproof membrane and vapour barrier. What makes the following drawing an extensive green roof is that it consists of a thinner planting medium layer ( ≤15 cm deep) with herbaceous vegetative cover that possess shallower root systems and is designed for SWM purposes, and generally don't provide public access.

Drawing is from Metro Vancouver's, Stormwater Source Control Design Guidelines document document. For further details about these cross section drawings please visit the link.

Permeable Pavements

Please see below a profile and plan view of a drawing of a standard permeable pavement composed of interlocking pavers located in a parking lot/laneway (location dependent upon estimated traffic and vehicular loading). The installation is designed with an underdrain in this drawing as the site has low permeability soil (< 15mm/hr), allowing for only partial infiltration in the system. The permeable paver installation also includes a cleanout for said underdrain in case of clogging, and is comprised of a crushed aggregate bedding layer, clean washed stone base, and subbase (more about these layers can be found under here OPSS aggregates & Choker layer). The entire facility is surrounded by a geotextile to retain these layers and separate them from the underlying soil subgrade, allowing the system to infiltrate water into the surrounding soil and prevent migration amongst said layers.

Drawings are from the City of Toronto's, Design Criteria for Green Infrastructure in the Right-of-Way document. For further details about these cross section drawings please visit the link.

Rainwater Harvesting

Please see below a profile and plan view of a drawing of a standard rainwater harvesting cistern located on a private/public property's frontage with either a high water table or contaminated subsoils, connected to the building's downspout. This example includes the use of a raingarden as a pretreatment option, along with an underdrain and overflow which both deposit treated rainwater into the holding cistern. If water is not used for irrigation purposes, etc. there is an attached overflow which connects to the municipality's storm sewer system.

Drawings are from the City of Toronto's Green Streets Technical Guidelines Appendices document. For further details about these cross section drawings please visit the link.

Bioswales / Enhanced Swales

Please find below two sets of profile and plan view drawings of a bioswale and enhanced swale installation. Both installations are located in between the front of a private homeowners' property and the roadway, known as a easement or frontage. The major difference between the two installations is the use of an underdrain for the bioswale, drainage layers, specialized filter media located underneath the geotextile underlain rip-rap so that it provides partial infiltration. Whereas, the enhanced swale provides full infiltration, through a fully vegetated surface, allowing water to travel down slowly to the undisturbed soil substrate below.

Drawings are from the City of Toronto's, Design Criteria for Green Infrastructure in the Right-of-Way document. For further details about these cross section drawings please visit the link.

Stormwater Tree Trenches

Please see below a plan and profile view of one of several variations of a stormwater planter (soil cell) along a roadway. This type of cross section installment showcases a tree trench in a continuous growing medium located under a hard boulevard/concrete surface that can withstand constant and heavy vehicular loads. Drawings are from the City of Toronto's Green Streets Technical Guidelines Appendices document. For further details about these cross section drawings please visit the link.

Rain Gardens

Please see below a plan and profile view of a rain garden, which possesses full infiltration and bioretention functions. In the plan view, note that the contributing area has water coming from both the building's roof, and paved areas, along with the driveway and directed towards the lowest area of the property, where the rain garden is located. This allows the feature to collect and to easily absorb rain and surface water into the ground on homeowners/businesses' properties. The installation also includes a pretreatment rock/concrete forebay to limit erosion and reduce higher velocity flows entering the rain garden, along with mulch, filter media and various planting zones with specific vegetation types that are best suited for these areas within the feature to assist in infiltration and removal of contaminants.

Drawings are from the City of Vancouver's Surface Water/Stormwater Design & Construction Requirements document. For further details about these cross section drawings please visit the link.

External Drawing Cross Sections

• City of Ottawa - LID Demonstration Project by Aquafor Beech Ltd.
• Oregon State University LID typicals by GreenGirl
• Plan drawings by Low Impact Development Center, Inc.
• Bioretention detail by Philly Water
• Permeable paving by Philly Water
• Pipe-in-stone infiltration by Philly Water

Proprietary

In our effort to make this guide as functional as possible, we have decided to include proprietary systems and links to manufacturers websites.
Inclusion of such links does not constitute endorsement by the Sustainable Technologies Evaluation Program.
Lists are ordered alphabetically; link updates are welcomed using the form below.

• ADS pipe
• Soil cells by Silvacell
• pretreatment by Hydro International

Sustainable Technologies Evaluation Program

Low 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.

The downward movement of water through the soil, the downward flow of runoff from the bottom of an infiltration BMP into the soil.

Loss of water from a drainage system as a result of percolation or absorption into the surrounding medium (e.g., the infiltration of water into the native soil through a perforated pipe wall as it is conveyed).

The downward movement of water through the soil, the downward flow of runoff from the bottom of an infiltration BMP into the soil.

Loss of water from a drainage system as a result of percolation or absorption into the surrounding medium (e.g., the infiltration of water into the native soil through a perforated pipe wall as it is conveyed).

A perforated pipe used to assist the draining of soils.

The portion of water precipitated onto a catchment area, which then 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.

The 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.

Soil, 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.

An 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.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Initial 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.

A thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens.

Stormwater Management

An 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 total mass of a pollutant entering a waterbody over a defined time period.

The net amount of something (e.g. chemical, such as phosphorus), calculated as the product of concentration and volume in a given time. Some BMPs significantly reduce loading of pollutants to the environment by reducing volume more so than concentration.

A broad category of particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates, and available in various particulate size gradations.

Filter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils.

The 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.

Tank used to store rainwater (typically roof runoff) for later use.

Land owned by the City Toronto or any other level of government or public agency (such as Toronto and Region Conservation Authority, Toronto Transit Commission, school boards).

The 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.

Human application of water to agricultural or recreational land for watering purposes. City of Toronto Wet Weather Flow Management November 2006 47

Linear 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.

A 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.

Linear 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.

Vegetated open channel, with check dams; designed to convey, treat and attenuate stormwater runoff.

The engineered soil component of bioretention cell or dry swale designs, typically with a high rate of infiltration and designed to retain contaminants through filtration and adsorption to particles.

The slow movement of water into or through a soil or drainage system.

Penetration of water through the ground surface.

A vegetated practice that collects and treats stormwater through sedimentation and filtration. Contributions to water cycle/water balance are through evapotranspiration only; no infiltration.

A lot level bioretention cell designed to receive and detain, infiltrate and filter runoff, typically used for discharge from downspouts.

A pretreatment basin at the inlet of a practice that allow settling out of sediment and associated contaminants suspended in urban runoff.

a top dressing over vegetation beds that provides suppresses weeds and helps retain soil moisture in bioretention cells, stormwater planters and dry swales.

Low impact development is a stormwater management and land development strategy applied at the parcel and subdivision scale that emphasizes conservation and use of on-site natural features integrated with engineered, small scale hydrologic controls to more closely mimic pre-development hydrologic functions.

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.