Given recent shortages and price increases, anything you can do to maximize your department’s annual investment in road salt represents an opportunity to save money that can be used elsewhere. That’s why chemicals in liquid form are increasingly popular for anti-icing, de-icing, and pre-wetting.
Liquids most often used to melt snow and ice on sidewalks, surface parking lots, and roads are:
- Salt brine (rock salt dissolved in water). Pure salt brine is effective from 15 degrees F and, depending on how much you paid for the salt, costs about 10 cents a gallon.
- Calcium chloride magnesium chloride for temperatures -15 degrees F.
- An agricultural byproduct such as sugar beet juice or distillery refuse.
Three liquid options
Anti-icing involves applying a liquid, usually salt brine, to pavement before the snow or ice storm begins. This is a proactive approach and melts from the bottom up. One benefit: Snow and ice don’t bond to the road because the liquid was applied before the storm. You can melt at least one-half inch of snow with one application.
Average application: 50 gallons per lane mile; 37 gallons per 1-acre parking area.
De-icing means you’re applying chemicals to accumulated snow or ice. This is a reactive approach to the storm and melts from the top down. Because a bond has already formed between the snow and pavement, de-icing is inherently more expensive than anti-icing.
Average application rate: whatever it takes to melt the hard pack
Pre-wetting: Without moisture, rock salt is ineffective. Pre-wetting involves applying a liquid such as brine to salt (or sand) before it’s spread on pavement. Melting immediately begins when the salt hits the road. This “pre-treatment” saves 30% to 40% in salt and is environmentally beneficial because it keeps salt particles from scattering and bouncing off pavement.
The liquid can be applied in one of three ways:
To the truck’s entire load via an overhead spray system; application rate = five to 15 gallons per ton of salt based on the chemical you’re using.
- Just to what’s in the bucket before it’s loaded into the truck; application rate = five to 15 gallons per ton of salt based on the chemical you’re using.
- Equip trucks with tanks and pump liquid to a spinner that applies the liquid to salt as it’s dispensed. Application rate for calcium or magnesium chloride = six to eight gallons per ton of salt; salt brine = 10 to 12 gallons per ton. The most important thing to remember about application rates is that you won’t get the expected results if you don’t use enough chemicals. But using too much of any one chemical is wasteful and, thus, financially inefficient.
Since application rates depend on the pavement temperature, here’s a good rule of thumb: As the temperature rises during a storm, decrease the rate. If the temperature falls, increase it.
—Tom Bair (firstname.lastname@example.org) is vice president of GVM Inc., East Berlin, Pa. Visit www.gvmsnow.com.