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[[File:Ice storm (1).jpg|thumb|Ice storm (1)]]
 
[[File:Ice storm (1).jpg|thumb|Ice storm (1)]]
 
===[[Underdrain |Underdrains]] and flow control devices===
 
===[[Underdrain |Underdrains]] and flow control devices===
[[Underdrain]] perforated pipes should be located below the frost line to reduce the threat of ice clogging. Ontario provincial standard drawings of frost penetration depth are available from the [https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx Ministry of Transportation] as OPSD 3090.100 for northern Ontario <ref> Ministry of Transportation. 2010. Foundation Frost Penetration Depths for Northern Ontario. OPSD 3090.100. Nov 2010. Rev.1. https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx </ref> and OPSD 3090.101 for southern Ontario <ref> Ministry of Transportation. 2010. Foundation Frost Penetration Depths for Southern Ontario. OPSD 3090.101. Nov 2010. Rev.1. https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx </ref>.<br>
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[[Underdrain]] perforated pipes that are appropriately sized and sloped to allow rapid drainage are not susceptible to ice clogging.  Underdrains below permeable pavements, for instance, are rarely below the frost line but have not been found to be susceptible to ice clogging.  Locating underdrains below the frost line would be important when there is a potential for groundwater flow in underdrains, where underdrain are flat, or where there may be slow entry of water into underdrains over long time periods. Ontario provincial standard drawings of frost penetration depth are available from the [https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx Ministry of Transportation] as OPSD 3090.100 for northern Ontario <ref> Ministry of Transportation. 2010. Foundation Frost Penetration Depths for Northern Ontario. OPSD 3090.100. Nov 2010. Rev.1. https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx </ref> and OPSD 3090.101 for southern Ontario <ref> Ministry of Transportation. 2010. Foundation Frost Penetration Depths for Southern Ontario. OPSD 3090.101. Nov 2010. Rev.1. https://www.library.mto.gov.on.ca/SydneyPLUS/TechPubs/Portal/tp/opsViews.aspx </ref>.<br>
 
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[[Weirs]] are generally less prone to clogging from ice than [[orifices]] or valves under all flow conditions. Proprietary low flow devices are also available which are designed to mitigate clogging from ice or other solid debris.
 
[[Weirs]] are generally less prone to clogging from ice than [[orifices]] or valves 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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