Item B - Ice and Snow Policy - Laserfiche WebLink

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Black Ice: Popular term for a very thin coating of clear, bubble-free, homogenous ice which forms on a pavement with a temperature at or slightly above 32 F when the temperature of the air in contact with the ground is below the freezing-point of water and small slightly super cooled water droplets deposit on the surface and coalesce (flow together) before freezing. Deicing: The application of liquid chemicals which penetrate into, then accelerate the melting of already formed frost, ice or snow which is bonded to the road surface. Freezing Rain: Super cooled droplets of liquid precipitation falling on a surface whose temperature is below or slightly above freezing, resulting in a hard, slick, generally thick coating of ice commonly called glaze or clear ice. Non-super cooled raindrops falling on a surface whose temperature is well below freezing will also result in glaze. Frost: Also called hoarfrost. Ice crystals in the form of scales, needles, feathers or fans deposit on surfaces cooled by radiation or by other processes. The deposit may be composed of drops of dew frozen after deposition and of ice formed directly from water vapor at a temperature below 32 F (sublimation) Light Snow: Snow falling at the rate of less than lA in. per hour; visibility is not affected adversely. Liquid Chemical: A chemical solution; the volume of solution applied per lane mile is the chemical application rate used in this appendix. Calcium Magnesium Acetate (CMA): CMA is a biodegradable product made up of limestone and acetic acid (a compound of vinegar). CMA is normally applied in liquid form to lower the freezing point of water and to prevent it from turning to ice. Magnesium Chloride (as defined for ice control): Is a salt compound extracted primarily from the Great Salt Lake, with added rust inhibitors, used to prevent or remove the build up of ice and snow on roads Moderate andHeavy Snow: Snow falling at a rate of lA in. per hour or greater; visibility is significantly reduced. Pre-wet Aggregate: Liquid chemical applied to aggregate before it is placed on pavement. Sleet: A mixture of rain and snow, which has been partially melted by falling through an atmosphere with a temperature slightly above freezing. Slush: Accumulation of snow, which lies on an impervious base and is saturated with water in excess of its freely drained capacity. It will not support any weight when stepped or driven on but will "squish" until the base support is reached.