LID opportunities on residential land

Residential LID options

On residential lands, hard surfaces such as roofs, patios, walkways and driveways can all be targeted to collect, treat, and infiltrate runoff. The practices you choose will vary depending on neighbourhood and site constraints and landscape ideals.

Landscape Alternatives

Landscape alternatives capture rainfall in leafy green foliage. This allows for infiltration, filtration, and evapotranspiration of rainfall and runoff. Well-designed landscape alternatives require little maintenance and less irrigation after establishment than sod lawns. They are a great water conservation tool.

Landscape alternatives allow homeowners to customize their property’s landscape to their liking. A guiding principle when designing landscape alternatives is “the right plant for the right place”. Using both native and non-native plants is acceptable as long as the non-native plants are not invasive and do not require frequent watering. Various landscape alternatives are available, including:

• Fusion Landscaping®
• Xeriscaping
• Tree Clusters

Fusion Landscaping®

The Region of Peel’s Fusion Landscaping® program is a great example of a landscape alternative. Fusion Landscaping® combines the lush splendour of traditional gardens with modern, eco-friendly plants. This program uses local market research and social marketing to promote behavioural change, to address residents’ unique needs, and to reduce outdoor water use.

Xeriscaping

Xeriscaping refers to landscaping, plantings and gardening practices that reduce or eliminate the need for watering. Synonymous with water conservation, xeriscaping was originally promoted in areas with perennial water shortages.

Xeriscaping involves selecting plants based on their ability to survive with little water. Water savings aside, additional benefits include reducing water bills, lowering maintenance requirements, and better plant survival rates and aesthetics during drought periods. Xeriscaping can be used on a lot-by-lot basis or in combination with larger residential LID programs.

Tree Clusters

Tree clusters are another residential landscape alternative. They intercept rainfall, allowing for evapotranspiration and for infiltration of stormwater runoff. Tree clusters improve water quality, generate organic soils, absorb greenhouse gases, and provide shade for homes. Tree clusters require larger lot sizes, preferably with no overhead wires. They can be planted as standalone features or as part of a larger residential LID landscape.

Rain Gardens

Rain gardens look like typical gardens. However, their infiltration and bioretention functions are much greater than normal gardens. By landscaping areas to include a surface depression of approximately 150 mm (6 inches), rain gardens allow runoff from residential properties to collect and to easily absorb into the ground. Within the rain garden, special types of soil, 'filter media' or soil amendments increase the amount of water absorbed by the garden and infiltrated into native soils.

Location is very important to a functioning rain garden. When looking at potential locations, look for low areas where runoff can be easily be directed into the garden. Rain gardens are a great option for residential LID retrofits because homeowners can customize the garden to suit their desired styles. They can be planted with a variety of vegetation including shrubs, grasses and flowers.

A well-designed rain garden can be maintained with minimal care, which is a great marketing point for persuading homeowners. In the first two years, the plants will need watering to ensure they become established. After this establishment period, the garden should only need simple maintenance, e.g. weeding.

Permeable Pavement

Permeable pavements are surfaces that encourage infiltration. They can be used in place of conventional asphalt or concrete pavement. These alternatives contain pores, spaces and joints for allowing stormwater to pass through to a stone base, where it infiltrates into underlying native soils or is temporarily detained. Types of permeable pavement include:

• Pervious concrete
• Porous asphalt
• Permeable interlocking concrete pavers (PICP, or just permeable pavers)

Permeable pavement can be used for both driveways and walkways. When infiltrating driveway runoff, confirm whether your residential neighbourhood is in a wellhead protection area. Driveway runoff should not be infiltrated if it is in a wellhead protection area due to the risk of groundwater contamination. Contact your local Conservation Authority for more information on wellhead protection areas.

Focus on aesthetic appeal when marketing permeable pavers to homeowners. They come in a variety of colours and shapes, and can be laid out to form patterns or designs that enhance the aesthetics of residential properties.

Permeable pavement may also appeal to homeowners because it typically has a longer life span that traditional asphalt. As well, light-coloured pavers typically require less winter maintenance. Water and snow generally seep through the joints of the pavers before ice can form, reducing the amount of salt homeowners need to use on their driveways, walkways or patios.

Soakaways and Infiltration Trenches

Soakaways, also known as infiltration galleries and dry wells, are excavations in native soil that are filled with clean granular stone. Soakaways are typically designed with a perforated pipe inlet from a relatively clean water source, such as a roof tops or pedestrian area. When possible, install soakaways in areas where native soils allow for infiltration. If poorly draining soils are present, an underdrain can be installed to remove standing water.

Where lot size is a constraint, a linear variation known as infiltration trenches can be used. This technique may be appropriate for sites where retrofit space is limited to long strips between buildings or along property lines.

Rainwater Harvesting

Rainwater harvesting is the process of collecting and storing rainwater for future use. Harvested water can be used for a variety of non-potable indoor and outdoor uses with minimal treatment. Rainwater harvesting provides an easy, low-cost option for homeowners to reduce the volume of runoff conveyed from their properties to the municipal storm sewer system.

Rainwater harvesting systems

Rainwater harvesting systems collect rainwater from roof runoff and store it until it is needed. These systems are typically used for irrigation. However, with additional equipment and proper treatment, this water can be used for flushing toilets and doing laundry. By using rainwater around the home, residents can reduce their water bills while also reducing the amount of stormwater runoff entering the storm sewer system.

Rainwater storage tanks come in a variety of dimensions and shapes to accommodate both the size and desired aesthetics of residential properties. They can fit unobtrusively against the home, be buried underground, or even be placed below a deck.

Rain Barrels

While they provide similar functions to rainwater harvesting systems, rain barrels have limited storage space. Rain barrels are installed at the outlet of downspouts and intercept water draining down roofs. Water collected in rain barrels can be used for irrigation. Rain barrels come in a variety of shapes, sizes and styles. Residents can choose a style of rain barrel best suited to their home and personal tastes. For example, rain barrels can be decorated to create garden art.

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

Penetration of water through the ground surface.

The technique of removing pollutants from runoff as it infiltrates through the soil.

The quantity of water transpired (given off). Retained in plant tissues, and evaporated from plant tissues and surrounding soil surfaces. Quantitatively it is usually expressed in terms of depth of water per unit area during a specified period. e.g. mm/day

The combined loss of water to the atmosphere from land and water surfaces by evaporation and from plants by transpiration.

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

Reduction in applied water due to more efficient water use such as implementation of Urban Best Management Practices or Agricultural Efficient Water Management Practices. The extent to which these actions actually create a savings in water supply depends on how they affect net water use and depletion.

Defined as those plants (including grasses, herbaceous species, shrubs, vines and trees) that have historically existed within a particular area. Native plants have co-evolved with the local ecosystems and natural processes.

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

A mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces.

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.

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 natural ground material characteristic of or existing by virtue of geographic origin.

Gravel, 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.

A perforated pipe used to assist the draining of soils.

Water ponded on the ground surface.

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.

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.