By Gerry Matthews
The benefits of anti-icing are considerable. Pretreating surfaces with ice melter before a storm arrives can increase winter safety, make subsequent snow & ice removal easier and less costly, minimize deicer usage, and reduce the potential for impact on properties and the environment.
Applying ice-melting chemicals before or at the start of freezing precipitation prevents formation of bonded ice on pavement, which can help ensure safe passage for pedestrians and motorists from the outset of a storm. Use of proactive anti-icing applications can be particularly useful on sidewalks, steps and parking lots, which can quickly become slip and fall hazards when freezing precipitation arrives. Anti-icing can also reduce the risk of accidents on roads and highways by preventing hazardous conditions to form on steep grades, bridges, sharp curves, in problem intersections, and on other potentially dangerous roadways.
Reduced deicer use
The U.S. Environmental Protection Agency (EPA) says effective pretreatments typically require up to 75% less ice melt material throughout the storm cycle compared to deicing after weather events, reducing costs as well as environmental impact.
The “Winter Parking Lot and Sidewalk Maintenance Manual” used in Minnesota states that anti-icing treatments applied in advance of foul weather often cost just one-tenth as much as deicing operations implemented after a storm.
Labor and cost savings
Pretreating pavement surfaces with ice melter can provide significant labor- and cost-saving benefits. Anti-icing treatment before a storm can often eliminate the need to remove light accumulations and can make removal of heavy snow and ice faster and easier. The residual ice-melting effect of these treatments can reduce the need for subsequent deicing applications after plowing.
Material selection depends on many factors, including available equipment, pavement temperatures, and current and expected weather conditions. Also important is the area requiring anti-icing treatment, which can affect economics and the selection of the most practical alternative. Three options include:
Liquid ice melter. A commercial liquid calcium chloride solution is a cost-effective choice when applying anti-icing treatments to roadways and other large areas of pavement. Liquid calcium chloride may be applied alone or in an enhanced blend of liquid calcium chloride with commercially available additives such as corrosion inhibitors and/or viscosity enhancers. A 30-32% concentrated solution of liquid calcium chloride is typically used.
Pre-wetted rock salt. Pre-wetted salt or treated salts with liquid calcium chloride additives may also be applied as an anti-icing pretreatment. The liquid calcium chloride provides the moisture rock salt needs to quickly begin to form the brine necessary to initiate melting action when freezing precipitation arrives. A solution of 30%-32% liquid calcium chloride is typically specified for pre-wetting applications, added at a rate of 6-10 gallons per ton of rock salt (25-42 liters per tonne).
Packaged solid ice melter. Solid calcium chloride ice melters used to melt ice on pedestrian walkways, building entranceways, parking lots and other pavement surfaces may also be applied as a proactive treatment prior to a storm.
Great Lakes Chloride, a distributor of liquid calcium chloride with more than 45 years of experience in anti-icing, offers the following recommendations for the use of liquid calcium chloride (30%-32% CaCl2 solution) for anti-icing in parking lot applications.
- Prior to frost or black ice event: 0.1 to 0.2 gallon per 1,000 sq.ft., 20°F to 30°F (-7°C to -1°C)
- Prior to light or moderate snow: 0.25 to 0.3 gallon per 1,000 sq.ft., 20°F to 30°F (-7°C to -1°C)
The recommendations are based on tenths of a gallon per 1,000 sq.ft. of parking lot and are starting points; they may need to be adjusted based on experience and weather conditions. It is recommended that variables be documented with each application so they can be referenced in planning future anti-icing treatments as part of a sensible approach to snow & ice control.
A variety of portable, walk-behind, and truck- or trailer-mounted equipment can be used for liquid applications. The same equipment used for applying solid calcium chloride for deicing can also be used for anti-icing treatments with pre-wetted salt or other solid deicer products.
On sidewalks, steps and entryways inaccessible to trucks or other motorized equipment, it is important to apply solid material evenly using a mechanical dispersing spreader and not a hand scoop to ensure full coverage and avoid wasteful deicer piles that could be tracked indoors. More even distribution can reduce waste by up to 50% and limit introduction of deicer into the environment.
Limitations and precautions
Anti-icing applications aren’t appropriate for all conditions. Anti-icing should not be attempted if rain is predicted because the treatment may wash away into the environment. Overapplication of liquid and solid anti-icing treatments should be avoided because they can produce slippery conditions. Finally, in storm events with heavier snowfall and dropping temperatures, anti-icing may not be effective in preventing ice and snow from bonding to the surface.
A sound strategy
Anti-icing is a proven way to provide safer conditions for motorists and pedestrians starting at the very outset of a winter storm event. It’s also a practical way to help minimize deicer use, reduce labor and cost, and minimize the impact on properties and the environment before, during and after a storm. It’s an effective and practical strategy for commercial snow professionals whenever they have advance warning that a storm is on the way.
Gerry Matthews is a senior account executive with Occidental Chemical Corporation (OxyChem).