Difference between revisions of "Winter"

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===Salt and Snow===
[[File:Dfb.png|thumb|Koppen World Map Dfb Dwb Dsb]]
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<p>Sodium and chloride ions in de-icing salts applied to asphalt areas travel easily with the runoff water.  De-icing salt can also 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). </p>
==Cold Climate==
<p> <strong>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).</strong>  </p>
The majority of Ontario has a [https://en.wikipedia.org/wiki/Humid_continental_climate#Koppen_Dfb| "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 LID strategies are routinely employed, including many northern states in the USA and a large swath of northern Europe.  
<p>To minimize risk of groundwater or soil contamination, the following management approaches are recommended (Pitt et al., 1999; TRCA, 2009b):
<ol>
<li>Stormwater infiltration practices should not receive runoff from the following areas:
<ul>
<li>Where large amounts of de-icing salts are applied (e.g., busy highways), or </li>
<li>Pollution hot spots (e.g. vehicle fuelling, servicing or demolition areas, outdoor storage or handling areas for hazardous materials, and some heavy industry sites); </li>
</ul>
<li>Prioritize infiltration of runoff from source areas that are comparatively less contaminated such as roofs, low traffic roads and parking areas; and </li>
<li>Apply [[pre-treatment practices]] before infiltration of road or parking area runoff. </li>
</ol>
</p>


===Planning===
==De-icing Salt==
Recommended planning strategies in designing sites for reduced salt usage:
See also: [[Salt management]]
<p><strong>Effective Grading</strong> Areas for vehicular and pedestrian traffic should be graded between 2 - 4% to reduce the chances of depressions forming. Sub bases should be well compacted for the same reason. Preventing ponding and ice formation reduces the salting requirements for those surfaces. In winter months efficient salt application should be made along the top of slopes. Melting snow will carry the salt solution down-gradient. </p>
[[File:Snow_filter_strip.png|thumb|Snow being stored on a filter strip in Markham, ON]]
<p><strong>Snow Piles</strong> Storage locations for snow piles should be in sunny areas with low traffic. Consider grading the storage location to distribute the melt-water as sheet flow over a [[Grass Filter Strips|grass filter strip]] into an adjacent BMP, such as a [[Bioretention Cells|bioretention cell]] or [[Infiltration Trenches|infiltration trench]]. In some cases, with careful vegetation selection and adequate drainage, the BMP itself can serve as a snow storage location. Snow storage areas should be clearly marked for seasonal maintenance staff.</p>
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 <ref>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</ref><ref>Bauske, B., Goetz, D. 1993. Effects of de-icing salts on heavy metal mobility. Acta Hydrochimica Hydrobiologica. Vol. 21. pp. 38-42., 1993).</ref>
<p><strong>Sidewalk Design and Pedestrian Flow</strong> Sidewalks which receive infrequent use could be closed for the winter season. Maintained sidewalks should be ≥ 1.5 m wide to accommodate plowing and minimize the salting required. Using textured pavers can improve grip for pedestrians, again reducing the salt required. In busy areas around building entrances, covered walkways and heated mats also reduce salt requirements.</p>  
<p><strong>Trees</strong> Specifying deciduous trees will maximize winter sunlight penetration. This will naturally enhance the melting of frozen surfaces, limiting the need to winter maintenance. </p>


<h5>Vegetation</h5>
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 <ref>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.</ref><ref>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.</ref>
<p>Vegetation varies in its reaction to salt-affected soils.  
<ul>
<li>Salt in soil water generally makes it more difficult for roots to take up water. This phenomenon mimics drought conditions for the plant. </li>
<li>If passing traffic sprays salty water onto plants it can reduce cold hardiness in buds and new twigs. These then become more susceptible to
freezing, mortality or deformation.</li>
<li>In high enough concentrations sodium and chloride can also be directly toxic to plants. In some species the ions are absorbed by t he plant and build up in the leaves causing them to die </li>
</ul>
Generally, the vegetation growing closest to the source will be most strongly affected by salt. Plants actively growing in late winter (when salt levels are highest) are also more significantly affected. So, warm season grasses offer an advantage over cool season grasses, because they emerge later in the spring when excess salt has been flushed away. </p>  


</div>
===To minimize risk of groundwater or soil contamination, the following management approaches are recommended (Pitt et al., 1999; TRCA, 2009b):===
<div class="col-md-4">
Stormwater infiltration practices should not receive runoff from the following areas:
<panelSuccess>
*Where large amounts of de-icing salts are applied (e.g., busy highways), or
<gallery mode="packed" widths=300px heights=300px>
*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
Snow_filter_strip.png| Snow being stored on a filter strip in Markham, ON
*Apply [[pretreatment]] practices before infiltration of road or parking area runoff.
</gallery>
 
</panelSuccess>
*http://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/pubs_specs_info/jee_3_09_unhsc_cold_climate.pdf
</div>
 
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==Other freezing related concerns==
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[[File:Ice storm (1).jpg|thumb|Ice storm (1)]]
===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 LID systems including curb inlets and permeable paving.


===Freezing and Expansion===
===Flow control devices===
</div>
LID 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 of 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.
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Freezing temperatures can cause problems with pipes and cisterns exposed above the frost penetration line[http://www.raqsb.mto.gov.on.ca/techpubs/ops.nsf/0/ee1f1756eacc00e18525808200628fbf/$FILE/OPSD3090.101%20Rev%231%20Nov2010.pdf].
This maybe a significant issue for [[Rainwater Harvesting|rainwater harvesting systems]], including residential [[Rain Barrels|rain barrels]].
</div>
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IMAGES?
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===See Also===
===Rainwater harvesting===
<ul>
Freezing temperatures can cause problems with pipes and cisterns exposed above the [http://www.raqsb.mto.gov.on.ca/techpubs/ops.nsf/0/ee1f1756eacc00e18525808200628fbf/$FILE/OPSD3090.101%20Rev%231%20Nov2010.pdf frost penetration line]. This maybe a significant issue for [[Rainwater harvesting|rainwater harvesting systems]], including residential [[Rain Barrels|rain barrels]].
<li>[[Water Quality]]</li>
===Green Roofs===
</ul>
The survival of [[Green roofs: Planting|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.
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Latest revision as of 15:53, 22 November 2019

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. These conditions are 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.

De-icing Salt[edit]

See also: Salt management

Snow being stored on a filter strip in Markham, ON

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 [1][2]

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 [3][4]

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

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]

Ice storm (1)

Plowing[edit]

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 LID systems including curb inlets and permeable paving.

Flow control devices[edit]

LID 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 of 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 harvesting[edit]

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

Green Roofs[edit]

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.

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

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 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.

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.

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