Winter

From LID SWM Planning and Design Guide
Revision as of 20:06, 1 August 2018 by Jenny Hill (talk | contribs) (Other freezing related concerns)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search
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. These conditions are found in many other parts of the world where LIDLow 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. strategies are routinely employed, including many northern states in the USA and a large swath of northern Europe.

De-icing Salt

See also: Salt management

Snow being stored on a filter stripa 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. in Markham, ON

Sodium and chloride ions in de-icing salts applied to asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. areas travel easily with the runoffThat potion of the water precipitated onto a catchment area, which 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. 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 [1][2]

Very few studies have sampled groundwater below infiltration facilities or roadside ditches receiving de-icing salt laden runoffThat potion of the water precipitated onto a catchment area, which 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. have found concentrations of heavy metals that exceed drinking water standards [3][4]

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

Stormwater infiltration practices should not receive runoffThat potion of the water precipitated onto a catchment area, which 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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. 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 runoffThat potion of the water precipitated onto a catchment area, which 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..

Other freezing related concerns

Plowing

Rubber plow blades are increasingly available and required in many jurisdictions. Their use reduces damage to all kinds of pavement surfaces and they are particularly recommended for application on LIDLow 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. systems including curb inlets or permeable pavingAn 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..

Flow control devices

LIDLow 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. facilities have been demonstrated to function well throughout frozen periods of the year even when all components were fully frozen for some part of the year. However, where the consequences of even temporary ponding would be entirely unacceptable, underdrains should be placed below the frost line to reduce the threat ice clogging. Weirs are generally less prone to clogging from ice than orifices under all flow conditions, proprietary low flow devices are also available which are designed to mitigate clogging from ice or other solid debris.

Rainwater harvestingThe 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.

Freezing temperatures can cause problems with pipes and cisternsTank used to store rainwater (typically roof runoff) for later use. exposed above the frost penetration line. This maybe a significant issue for rainwater harvesting systems, including residential rain barrels.

Green Roofs

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 are associated higher loss of vegetation on green roofs.


  1. Amrhein, C., Strong, J.E., and Mosher, P.A. 1992. Effect of de-icing salts on metal and organic matter mobilization in roadside soils. Environmental Science and Technology. Vol. 26, No. 4, pp. 703-709
  2. Bauske, B., Goetz, D. 1993. Effects of de-icing salts on heavy metal mobility. Acta Hydrochimica Hydrobiologica. Vol. 21. pp. 38-42., 1993).
  3. Howard, K.W.F. and Beck, P.J. 1993. Hydrogeochemical implications of groundwater contamination by road de-icing chemicals. Journal of Contaminant Hydrology. Vol. 12. pp. 245-268.
  4. Granato, G.E., Church, P.E., Stone, V.J. 1995. Mobilization of Major and Trace Constituents of Highway Runoff in Groundwater Potentially Caused by De-icing Chemical Migration. Transportation Research Record. No. 1483.