Keeping roads safe: alternative de-icers |

Keeping roads safe: alternative de-icers

Magnesium chloride

– What: A mixture of 70 percent distilled water, 27 percent salt and 3 percent rust inhibitors sprayed on roadways before a storm to lower the melting point of snow, thus preventing snow and ice from sticking to roads. The Colorado Department of Transportation (CDOT) uses the product along Interstate 70, and many towns use it on heavily traveled roadways, curves, steep hills, roundabouts and intersections.

– Cost: $90 per ton

– Advantages: Studies – including those conducted by the Colorado Association of Transit Agencies, CDOT, the Colorado Department of Public Health and Environment and independent researchers – show mag chloride is highly effective at temperatures down to about 25 degrees, but only until snowmelt dilutes the compound to the point it can refreeze. Rust inhibitors, which include small quantities of heavy metals such as cadmium, arsenic and lead, make magnesium chloride less corrosive than other products. Unlike sand and volcanic cinders, mag chloride does not clog streams or contribute to air pollution.

– Disadvantages: Mag chloride gets splashed onto windshields and headlights, and its sticky nature makes it difficult to remove. It also corrodes copper wiring. Vehicle repair shop owners claim the chemical causes deterioration in car parts, notably brakes, ball joints and rubber parts, faster than salt and sand mixtures. Other studies, notably those conducted by various state transportation departments, indicate it is less corrosive than other chemicals. State studies so far indicate that the concentration at which the chemical is usually mixed does not harm plants, animals or streams.

Mark Stutz, spokesman for cel Energy, said company officials believe most of the power pole fires to which they respond every year are primarily a consequence of dried magnesium chloride. When roadways that have had mag chloride applied to them dry out, vehicle traffic grinds the powder into a fine dust that settles on the poles and equipment. When a storm moves through, the chemical buildup allows the electricity flowing through the wires to arc, starting a fire.

For cel, however, it’s just another part of doing business, as is dealing with heavy snows, squirrels that jump from wire to wire and contractors who accidentally cut wires while digging.

“Generally speaking, when we get a pole fire, it’s mag chloride that’s the culprit,” Stutz said. “Mag chloride is difficult for operations, but on the flip side, it makes the roads safer, and it eliminates problems with people driving into our equipment – those numbers are down. We do support the use of mag chloride, even though on certain days it creates operational problems.”

– Who uses it: CDOT, Vail, Glenwood Springs, Dillon and Avon (limited use)

Salt, sand and plowing

– What: A procedure that involves plowing the roads, then strewing a sand and salt mixture – sometimes as high as 25 percent salt – onto roads. The sand provides traction; the salt melts snow and ice.

– Cost: $19-$30 per ton

– Advantages: Salt and sand serve drivers well if roads can be kept clear. Best for use on roads where cars go fast, like on the interstate. Salt melts snow quickly and efficiently.

– Disadvantages: If snow is falling hard, it can be difficult for plow operators to keep up with applications. Before magnesium chloride was used on Interstate 70 as a de-icer, plow operators had to apply sand and salt continually to ensure safety. During heavy snowstorms, layers of snow and sand could accumulate – in some places up to a foot thick. Salt is extremely corrosive; depending on the proportion, a salt-and-sand mixture can be five to 15 times more corrosive than magnesium chloride. Salt is toxic to many native plant species. Sand can pit windshields. Cars grind sand into a fine dust that contributes to air and water pollution.

Sand is the primary culprit behind the “Brown Cloud” that loomed over Denver in the 1980s.

– Who uses it: CDOT and municipalities in Summit, Eagle, Pitkin and Garfield counties

Volcanic cinders (aka scoria)

– What: Small, volcanic rocks mined in McCoy. The red rocks, which are also used in landscaping, are porous, light and coarse.

– Cost: $25 per ton, delivered

– Advantages: The town of Vail uses cinders in residential neighborhoods where cars don’t go as fast. Cinders, which are slightly larger than sand, grip the snow well and provide good traction.

– Disadvantages: After the snow melts, cinders can be ground into a fine dust that can contribute to air and water pollution. Vail does not use cinders in its pedestrian villages because people track the ground dust into stores. The town also uses street sweepers every year to retrieve sand and cinders and resells the mixture. Cinders don’t work well on icy roads because when they’re applied, they bounce off.

– Who uses it: Avon, Vail

Three-eighths rock

– What: Rock ground to a 3/8-inch diameter.

– Cost: $19 per ton

– Advantages: Three-eighths rock is larger than sand or cinders and used in pedestrian areas to provide traction. Its larger-size pieces can’t be ground down as easily as sand and cinders, so it doesn’t track into stores, streams or into the air. The rock is good on icy surfaces.

– Disadvantages: If kicked up by other vehicles; it can crack and pit windshields.

– Who uses it: Vail, in pedestrian areas


– What: A liquid ice-melt made from a corn byproduct and alcohol. Sometimes it is mixed with other salt-based de-icers to increase its effectiveness.

– Costs: About $100 per ton

– Advantages: Melts ice and snow. The manufacturer claims it’s good up to seven days. Considered to be environmentally friendly. Is less corrosive than water. Washes off vehicles easily.

– Disadvantages: Refreezes faster than other products. About 10 to 12 cents more per gallon than magnesium chloride.

– Who uses it: No one in the High Country

Calcium magnesium acetate

– What: a blend of 40 percent calcium magnesium acetate (CMA) and 60 percent rock salt. CMA, made from dolomitic lime and acetic acid, is usually applied in pellet form and is often used as a corrosion inhibitor in de-icer blends.

– Cost: ranges from $300 to $1,400 per ton, depending on the supplier and where it’s purchased

– Advantages: CMA has little to no toxic effects on aquatic species, does not increase algae in waterways, is biodegradable and noncorrosive. CMA is effective in penetrating light snowpack and preventing snow from bonding to pavement. Because of the sticky nature of the chemical, road maintenance workers don’t need to apply it as often as other products.

– Disadvantages: Must be stored in temperatures above minus 7. It is expensive. Twice as much CMA has to be used as salt to be effective. In tests, CMA has been found to be less effective on fluffy snow and in conditions below 23 degrees.

– Who uses it: No one in the High Country

Others available

– Calcium chloride, Calcium potassium acetate, potassium formiate, potassium chloride acetate, magnesium acetate, anhydrous sodium acetate.

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