Winter

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Koppen World Map Dfb Dwb Dsb

Cold Climate[edit]

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[edit]

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[edit]

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.