Conscious Choice: Slip-Sliding, Away!

January 1999

Slip-Sliding, Away!

A review of the available options, and their environmental, safety, and efficiency implications

by Ana Arias Terry

The irony of chance can strike at the most peculiar times. During the days I was researching this article, I had to drive to town for a meeting. On my way there, the tires passed over a long patch of hidden ice that sabotaged my control of the steering and brakes. While I’m a self-described treehugger, I wasn’t thrilled about the prospect of becoming one with a tree under these circumstances.

Fortunately, the damage to tree, car, and yours truly was minimal. But the incident served to boost my already healthy curiosity about alternatives to melting snow and ice and the range of their spectrum on an ecological, safety, and performance scale.

Assessing the Options
Okay. Let’s say this winter you’ve decided to tackle the driveway and sidewalk snow and ice issue on a more active and educated note. A good place to start is to familiarize yourself with the range of options available and see what course of action may suit you (and the environment) best.

The alternatives can be classified into four categories: 1) my personal favorite, the old-fashioned physical exercise route with shovel and flat hoe in hand; 2) easy-access options such as ashes, kitty litter, and sand; 3) commonly-available deicer chemicals; and 4) hydronic heating systems.

Getting Physical
We all know about the exhilarating powers of fresh air and exercise. And while many of us don’t habitually greet the process of bundling against the elements with shovel in one hand and flat hoe in the other, with passionate enthusiasm, attitude is key. Let’s take stock of the positives.

For starters, by using shovel and flat hoe to remove snow and ice, we can feel good about not contributing to the chemical equation that runs off into water systems, soil, and vegetation. Carefully watching where we step, we have a chance not only to exercise our heart and awaken dormant muscle groups, but to release a little stress in the process of the physical activity. Got a problem at work you’ve not been able to solve? Try a bit of measured flat hoe action on the ice at this point. Creativity works in mysterious ways.

If you’re physically unable to do the work yourself, hire a student or trade services with a neighbor to follow your wishes. After a startled look or two and some fine- tuning on the price or prize for services to be rendered with each snow fall or icy conditions, you’ll feel good about the choice.

A word of caution about physical methods learned from my husband. As an enthusiastic Eco-minded teenager, he volunteered to remove ice from his parents’ driveway. Despite his careful efforts with a dirt shovel — and much to his parents’ chagrin — he severely damaged the blacktop material (imagine the tragedy if he’d had a pick-ax!). Rather than chipping the heck out of paved surfaces with a pick-ax, a flat hoe can help you pry off the ice without the same risk of severe damage, though you still want to be careful.

Handy Options
Depending where they live and the options readily available, some people sprinkle (or dump, depending on how much they think more is better) ashes or kitty litter on their driveway and sidewalk.

Ashes, unfortunately, don’t have any particularly stellar effects on snow. Ash can assist with traction, but it offers no ice melting properties. Cat litter, basically a clay-based product, offers similarly unimpressive results. Much as trash doesn’t belong in plants and water systems, heaps of ashes and cat litter may negatively affect your vegetation and run into waterways. So the issue of properly disposing of the leftover muck needs consideration. Ever see a neighbor shoveling the leftovers into a trash can? Me neither.

Sand is a commonly used easy-access option. Like its previously mentioned cohorts, sand offers no melting actio, but its traction qualities between ice and vehicles (until it is kicked up to the side of roads) are far superior to ash and cat litter, due to its abrasive nature.

Henry Kirchner is a Professional Engineer registered in Michigan with 18 years experience in de-icers and winter maintenance. Now a consultant for companies and the legal profession, he explains that environmental and social consequences exist from using sand. These include the clogging of sewer systems, greater potential of corrosion to vehicles from hard-hitting sand pebbles that scratch the auto’s finish, and increased risk of scratched or chipped windshields from the motion of cars that cause the sand to act as sandblasters.

Kirchner and Bruce Juelfs, streets supervisor for the city of Fort Collins, Colorado, share similar concerns about the impact of sand. Of special concern to both is the deterioration of air quality that occurs in areas where sand is heavily used. Besides the costly and time-consuming job of sweeping sand from streets, sand crushed by cars forms microparticles that become airborne and pollute the air. Because the micro particles are breathable, they can be especially nasty for people with respiratory problems. In some areas, almost half of the brown cloud effect results from this sanding issue.

Deicer Smorgasbord
You don’t need to become a chemist or an engineer to understand the process of deicing, the most effective technique, and the various chemicals used widely for melting snow and ice. But it is helpful to learn something of their composition so you know what you’re buying, if you choose this option.

First things first. Kirchner says many people don’t properly use chemical deicers. A common method is to dump heavy (and unnecessary) amounts of the deicer and not shovel the driveway, sidewalk, or steps until every inch of snow and ice has melted. Kirchner says this is not only impractical but often leads to other problems. "The correct way to use a deicing agent is to spread it according to the manufacturer’s instruction, wait for melting action to break the bond between the ice and pavement, and then mechanically or manually remove the remaining ice and snow" toward the street and away from the vegetation.3 By using the appropriate amount of the chemical, you reduce the chances of causing damage to plant and grasses from high concentrations in the soil; at the same time, you save money because you’re not using as much.

By lowering the melting point of ice, deicer chemicals wipe out ice and snow off pavement. They work by being exposed to or attracting sufficient moisture to dissolve and form a brine (a saline solution). This solution then permeates the ice and snow until it encounters the pavement. Here it flows outward, breaking the bond between ice and snow, and pavement and, thus making it easier for shoveling or plowing. Although all chemical deicers display a similar behavior, significant differences do exist amongst the effectiveness levels of various products. One reason is that it takes some chemicals longer to form the solution, thus taking them longer to seep into snow and ice.

There’s one other practical bit of information that’s useful to know when you evaluate claims from manufacturers. According to Kirchner, such claims are generally based on the "theoretical lowest temperature to which the deicer can suppress the freezing point of water — called the eutectic temperature — which can only be reached at the ideal percent concentration of the deicer in water." And because these chemicals get significantly diluted the more they melt, they only stay at this ideal concentration for a very short time.

Hence, a more realistic assessment of the chemical’s low temperature efficiency is its practical working temperature. According to Kirchner, "It simply means the commonly accepted temperature that the deicer will show melting results within an acceptable timeframe." The melting of snow and ice by the deicer will still occur below this working temperature, but more slowly.

Now for the deicers themselves. Approximately 95 percent of the chemical deicers available today are based on one or several of these five components: sodium chloride (rock salt); potassium chloride and urea (both fertilizers); calcium chloride; and magnesium chloride. Then there exist acetates such as calcium magnesium acetate (CMA), which some landscape consultants maintain is eco friendly, less corrosive, and biodegrable. Of course, any chemical ice melter can harm the environment if used excessively.

Sodium chloride or rock salt is the most commonly used deicer. It melts snow and ice very efficiently, it’s cheap, but it’s also somewhat limited in its performance capability in very cold temperatures. Its practical working temperature hovers around 15-20 degrees F though its eutectic temperature can be as low as -7 degrees F.

According to Alexander Mathews, a professor of civil engineering at Kansas State University, it can also shorten the life span of concrete pavement, highway infrastructure, and cars, from corrosion. Additionally, "Sodium chloride can cause long-term ecological damage to the terrestrial and aquatic environment," says Mathews. "Increased salinity can alter species balance and stratification and seasonal mixing of lakes. Soil permeability is reduced, and the increased salt concentration will affect growth of plant species and diversity. Also, salt is known to increase the mobility of heavy metals such as lead in soils." Insofar as wildlife goes, Kirchner says that he knows of instances where the kill rate of deer on highways is higher because they’ve been drawn to the road to lick the salt.

Potassium chloride and urea are fertilizers commonly used in combating snow and ice. As fertilizers, they are perceived frequently as being safe alternatives to use near vegetation. But because in their role as deicers they are used in heavier concentrations, they can burn grass and other plant biota at roots and foliage if overused. The practical working temperature for these chemicals range between 20-25 degrees F with an eutectic temperature of between 11-12 degrees F. They can be as much as five times more expensive than rock salt. Because urea contains no chlorides, it’s not as corrosive, it’s more safe on concrete that contains rebar, and is frequently mixed with other ice melters to maximize its strengths with other chemicals.

Calcium chloride is sometimes referred to as a "hot salt" because it generates heat when it converts into a liquid and melts snow and ice. It’s the only one of the ice melters that exhibits this exothermic characteristics. Rock salt and fertilizers need heat (endothermic) from their environment to work. In its natural state, this chemical is a liquid brine that is then converted into a dry component when water is removed.

A particular advantage of this chemical is that because it absorbs moisture quickly from the atmosphere — unlike rock salt and fertilizers which have to come into direct contact with moisture that’s simply not available at low temperatures — it’s highly efficient in very cold weather. Its practical working temperature is -25 degrees F while its eutectic temperature reaches down to -60 degrees F. It can cost three to five times more than rock salt, and, according to Mathews, it can cause problems similar to those caused by rock salt.

Kirchner thinks of all the deicers, calcium chloride is the most environmentally friendly — not because of its chemical properties but because it’s so effective at undercutting ice you use significantly less than the others. You only need between 2-4oz. per square yard, the average being 3oz., as opposed to 8oz. of other deicers such as rock salt and urea.

The similarities between magnesium chloride and calcium chloride are significant. The primary disadvantage of the former is that because it’s only 48% active, its application needs to occur at twice the rate of the latter.

Calcium magnesium acetate (CMA) is a non-corrosive deicer that can be made from corn but is often petroleum based. It’s used more commonly by municipalities for bridges and parking decks. Rather than melting ice, it converts it into an oatmeal consistency, which is not a particularly useful feature for sidewalks and driveways. In addition it’s highly expensive, costing four to five times the price of the already pricey calcium chloride.

Innovative developments for CMA, however, are taking place. Professor Mathews has been working on a CMA/propionate deicer over the past eight years. In addition to using natural elements such as grain dust, starch, cellulose, straw, and wheat to make this product, he has used whey permeate from cheese manufacturing. Sit’s generally coated with sand prior to application so it doesn’t get blown by the wind.

A whey-based product such as this one could go a long way toward ameliorating both the corrosion problem caused by salt and the environmental problem caused by the disposal of whey. The dairy industry faces a serious predicament because cheese manufacturing produces massive quantities of whey that are not used.

Another advantage of this product is that "Acetate and propionate are naturally degraded by microorganisms in the environment," adds Mathews, "and calcium and magnesium improve soil properties."

While petroleum-based CMA is available today at about $1,000 per ton, the product Mathews and his colleagues are pursuing is estimated to cost $330 per ton. Kansas State University is negotiating possible licenses to manufacturers who will first market to municipality entities but will likely market the whey-based product to consumers soon thereafter.

Hydronic Heating Systems
Hydronic heating systems offer a different alternative to melting ice and snow on driveways or sidewalks by using water (or water-based solutions) to circulate thermal energy from where it’s produced to where it’s required. Water absorbs thermal energy at a heat source. Then the thermal energy is transferred by the water via pipes, and ultimately expelled into a space that’s heated by way of a heat emitter.

Steve Troy, president of Jade Mountain, a company based out of Boulder, Colorado, that sells "appropriate technology" products worldwide in support of sustainable living (including do-it-yourself radiant heat control packages), says hydronic radiant snow and ice melting systems are environmentally sound, efficient, and cost-effective when amortized. They work just like indoor radiant floors and other hydronic distribution systems (e.g., hot water baseboards, radiant towel bars, fan convectors, etc.), " — except that the tubing runs in the cement of sidewalks and driveways instead of inside the house." When the water or water mixture is heated by a boiler, for example, the surface of the pavement is heated enough to melt the ice and snow and dry the pavement.

"The heat is best supplied by solar water panels on the roof," says Troy, "but it can also come from a demand water heater or a conventional boiler." As for other heat sources, Troy points out that greywater, such as hot water from showers, laundry, etc., is another viable, eco option. "This could be part of a greywater system that reuses the water for irrigation, or the water could go into a conventional system after doing its snow melting job."

The cost of the pipe systems for such a system depends on the dimensions of the driveway or sidewalk, of course, but can run about $1 per foot. The number of solar collectors needed depends on variables such as the variation of temperature in your area and the location of your home. According to Troy, used solar collectors can cost $200 while deluxe versions can run as high as $700. Depending on your needs and preferences, you can always do a hybrid combination of solar heating with either propane or natural gas as backups.

This option offers a particularly attractive advantage for new home construction. Perhaps the only real disadvantage to such a system is that retrofitting homes already built is difficult.

Eeny, Meeny, Miney, Mo
Selecting the most appropriate method of removing ice and snow from your sidewalk, driveway, or steps ought to be an intentional, educated choice. My bias toward shovel and flat hoe sans chemicals may not be the decision you make for yourself. For others, the hydronic heating system may not be in the cards until the next major house project or new environmentally-based home construction.

If you choose one of the chemical options, spend a little time reviewing the pros and cons of the individual properties and weigh that against your perception of the most environmentally sound option, your budget, your area’s temperatures in relation to the chemical’s practical working temperatures, the surfaces to be cleared, and the manufacturer recommended application concentrations. Keep in mind that overuse is wasteful, unnecessary, and ecologically damaging. The purpose of deicers is not to exempt you from putting a little elbow grease into shoveling but rather to make the removal process easier for you.
When choosing between pellets and flakes regardless of deicer, select pellets because they’re much more effective at penetrating ice.

Although numerous manufacturers claim that their product is non-tracking, the bottom line is that if they melt ice and snow, they’ll form slush. Slush usually makes it into homes unless you take your shoes off outside. Check out deicers that are easy to clean (e.g., liquid-form calcium chloride, which doesn’t create the chalky residue on floors, carpets, and sidewalks that dry formulations do).

If you’d consider becoming more active in your quest for efficient snow and ice removal with deicers, you can use the anti-icing technique by applying a little chemical as soon as you see the first flake or icy condition so as to prevent the bond forming between pavement and ice, and shoveling soon after the inclement weather. Overall you end up using less chemical and the shoveling action is easier.

If after evaluating all the options you choose the straight physical alternative, drop me a line so we can compare notes. In the grand scheme, what’s a few sore muscle groups in the name of the planet?

De-icing Distributors and/or Manufacturers
EnviroTech Services, 800-369-3878
Cargill Salt, 800-227-4455

Hydronic Heating Systems
Jade Mountain, 800-442-1972
Shelter Products, 503-620-9662

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