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− | ===Salt and Snow===
| + | [[File:Dfb.png|thumb|Koppen World Map Dfb Dwb Dsb]] |
− | <div class="col-md-8">
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| {{TOClimit|2}} | | {{TOClimit|2}} |
− | <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 the metal(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):
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− | <ol>
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− | <li>Stormwater infiltration practices should not receive runoff from the following areas:
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− | <ul>
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− | <li>Where large amounts of de-icing salts are applied (e.g., busy highways), or </li>
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− | <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>
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− | </ul>
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− | <li>Prioritize infiltration of runoff from source areas that are comparatively less contaminated such as roofs, low traffic roads and parking areas; and </li>
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− | <li>Apply [[pre-treatment practices]] before infiltration of road or parking area runoff. </li>
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− | </ol>
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− | </p>
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− | <p>Vegetation varies in its reaction to salt-affected soils.
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− | <ul>
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− | <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>
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− | <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
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− | freezing, mortality or deformation.</li>
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− | <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>
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− | </ul>
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− | <p> Generally, the vegetation growing closest to the source will be most strongly affected by salt. </p>
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− | <p> 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>
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− | </div>
| + | ==De-icing Salt== |
− | <div class="col-md-4">
| + | See also: [[Salt management]] |
− | <panelSuccess>
| + | [[File:Snow_filter_strip.png|thumb|Snow being stored on a filter strip in Markham, ON]] |
− | <gallery mode="packed" widths=300px heights=300px>
| + | 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> |
− | Snow_filter_strip.png| Snow being stored on a filter strip in Markham, ON | + | |
− | </gallery> | + | 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> |
− | </panelSuccess> | + | |
− | </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-12"> | + | 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. |
| | | |
− | ===Freezing and Expansion===
| + | *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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− | <div class="col-md-8">
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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/$FILE/OPSD3090.101%20Rev%231%20Nov2010.pdf].
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− | This maybe a significant issue for [[Rainwater Harvesting|rainwater harvesting systems]], including residential [[Rain Barrels|rain barrels]].
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− | </div>
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− | IMAGES?
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− | </div>
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− | <div class="col-md-12">
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− | ----
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− | ===See Also=== | + | ==Other freezing related concerns== |
− | <ul>
| + | ===Plowing=== |
− | <li>[[Water Quality]]</li>
| + | Rubber plow blades are increasingly available and required in many jurisdictions. Their use reduces damage to all kinds of pavement surfaces and they are particularly recommended for application on LID systems including curb inlets or permeable paving. |
− | </ul>
| + | ===Flow control devices=== |
| + | LID facilities have been demonstrated to function well throughout frozen periods of the year even when all components were fully frozen for some part of the year. However, where the consequences of even temporary ponding would be entirely unacceptable, [[underdrains]] should be placed below the frost line to reduce the threat ice clogging. [[Weirs]] are generally less prone to clogging from ice than [[orifices]] under all flow conditions, proprietary low flow devices are also available which are designed to mitigate clogging from ice or other solid debris. |
| + | ===Rainwater harvesting=== |
| + | Freezing temperatures can cause problems with pipes and cisterns exposed above the [http://www.raqsb.mto.gov.on.ca/techpubs/ops.nsf/0/ee1f1756eacc00e18525808200628fbf/$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]]. |
| + | ===Green Roofs=== |
| + | 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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