Winter Management

Koppen World Map Dfb Dwb Dsb

Cold Climate

The majority of Ontario has a "Humid continental" Dfb climate, which includes average temperatures in the coldest month well below -3°C. This condition is found in many other parts of the world where LID strategies are routinely employed, including many northern states in the USA and a large swath of northern Europe. Common concerns associated with the use of LID during out

De-icing Salt

Snow being stored on a filter strip in Markham, ON

De-icing

Sodium and chloride ions in de-icing salts applied to asphalt areas travel easily with the runoff water. De-icing salt can increase the mobility of some heavy metals in soil (e.g. lead, copper or cadmium). This may increase the downstream concentration of these metals (Amrhein et al., 1992; Bauske and Goetz, 1993).

http://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/pubs_specs_info/jee_3_09_unhsc_cold_climate.pdf

Very few studies have sampled groundwater below infiltration facilities or roadside ditches receiving de-icing salt laden runoff have found concentrations of heavy metals that exceed drinking water standards (e.g., Howard and Beck, 1993; Granato et al., 1995).

To minimize risk of groundwater or soil contamination, the following management approaches are recommended (Pitt et al., 1999; TRCA, 2009b):

Stormwater infiltration practices should not receive runoff from the following areas:

• Where large amounts of de-icing salts are applied (e.g., busy highways), or
• Pollution hot spots (e.g. vehicle fuelling, servicing or demolition areas, outdoor storage or handling areas for hazardous materials, and some heavy industry sites); *Prioritize infiltration of runoff from source areas that are comparatively less contaminated such as roofs, low traffic roads and parking areas; and
• Apply pretreatment practices before infiltration of road or parking area runoff.

Other freezing related concerns

Rainwater harvesting

Freezing temperatures can cause problems with pipes and cisterns exposed above the frost penetration line[1]. This maybe a significant issue for rainwater harvesting systems, including residential rain barrels.

Green Roofs

Somewhat counter-intuitively, the survival of green roof planting is greater in winters with long deep sub-zero temperatures. Being shallow and very exposed to warming sunlight, green roofs thaw rapidly. Frequent freeze-thaw cycles in the early and late winter is associated higher loss of vegetation on green roofs.

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 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.

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

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.

Toronto and Region Conservation Authority

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.

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.