Site assessment of residential

Having a comprehensive understanding of site conditions is critical for Screening LID Options

Desktop Analysis of Background Information

A thorough assessment of background information is critical to understanding site conditions for residential lots or neighborhood. As you begin gathering and reviewing the noted background information, it is also important to determine any existing infrastructure gaps and planned upgrades, resident concerns, community greening, water usage and basement flooding. The following information should be considered to conduct a desktop analysis of background information

• Watershed studies,
• subwatershed studies,
• stormwater master plans
• Sewershed delineation
• Areas of identified storm sewer capacity issues
• Area contributing to combined sewer overflows
• Areas of degraded water quality
• Areas prone to flooding (both urban and riverine)
• Water quality targets
• Flow targets
• Infiltration targets
• The impact of planned development on existing infrastructure and watershed health
• Source water protection plans
• Well head protection areas (quantity and quality)
• Surficial Geology
  • Soil characterization
  • Groundwater levels
• Applicable Bylaws

Typical Bylaws	General Provisions May Include	Impacts on LID Options
Nuisance weeds and tall grass by-law	Designates tall grass and weeds as a public nuisance Defines “tall grass” as grasses over a maximum height (typically 20 - 30 centimeters) Requires tall grass to be cut to a height not exceeding the maximum Requires all nuisance weeds and weed seeds to be removed from a property by the owner. The municipality may carry out the work to bring properties into compliance and recover the cost from the land owner	Vegetated LID practices (specifically those with prairie or ornamental grasses) an landscape naturalization may be in violation of this existing by-law
Property standards by-laws	Sets minimum requirements for privately owned properties Restricts low lying areas including those that have been excavated that accumulate water, and directs them such that they be drained, filled and graded so that water drains to a storm sewer or ditch. Requires that all landscaped areas be cut and maintained in a reasonable condition in relation to the neighboring environment	Can preclude the implementation LID practices such as bioretention facilities as they are designed be both low lying and include ‘shallow’ surface ponding. May be considered prohibitive for the implementation naturalized landscape approach
Sewer use by-laws	Although generally limited to sanitary sewers, many municipalities now include storm water within this by-law. It generally requires all storm water to be discharged to an approved outlet and regulates the constituents of the discharged water.	May not permit direct discharge of roof water to the municipal storm sewer system. This may include overflow from rainwater harvesting tanks and other such devices
Standing water by-law	Prevents accumulation of water on an individual property within any depression Often in response to mosquito breeding and West Nile Virus concerns. Accumulation is typically defined per a determined period of time (e.g. 48 hours)	May be interpreted as prohibitive for soakaways subsurface storage facilities, bioretention, and bioswales
Boulevard planting by-laws	Regulates the type of vegetation that can be planted within the boulevard area	May inhibit bio-swales or vegetated swales due to plant type and height restrictions of planting along municipal boulevards.
Roof Leader policies (often as part of property standards by-laws	Regulates the collection and allowable discharge location of roof drainage May specify outlet distance from building foundation May prohibit discharge to storm sewers, impervious surfaces and property boundaries	Progressive roof leader policies can encourage the implementation of rain gardens, soakaways, rain barrels, and other LID practices

Field Reconnaissance

• Neighbourhood characteristics
• General lot characteristics
  • % of property coverage by house
  • Driveway sizes
  • Drivway types (% of asphalt, gravel, block pavers, etc.)
  • % of property covered by turf
  • % of property covered by alternative landscaping
  • % of property covered by trees
  • Location and general condtion of gardens
  • Distribution and coverage of natural vegetation
  • Location of septic systems
  • Location and style off fencing
  • Prevalence of irrigation systems
  • roadside swales
  • % cur
• Drainage characteristics
• Rooftop / drainage characteristics
• Best management practices info
• Recommended actions

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.

A long narrow trench or furrow dug in the ground, as for irrigation, drainage, or a boundary line.

Refers 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.

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

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.

Water ponded on the ground surface.

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.

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.

Natural or artificial means of intercepting and removing surface or subsurface water (usually by gravity).

A hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil.

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

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