Cold Weather Suggestions
Put Your Sidewalk and Driveway on a Low Salt Diet
Keeping ice and snow off your driveway and sidewalks is important for safety. Salt and sand have traditionally been perceived as the cheapest and most effective materials for de-icing surfaces. However, many people do not realize that many of these products have hidden impacts.
When ice melts, the salt and chemicals dissolve and flow into street drains that lead directly to a stream in our watershed. Depending on the product used, these impacts can range from creating dangerous changes in water salinity, to reducing oxygen levels in our streams and rivers, to "burning" or killing vegetation along sidewalks and roadsides, to damaging concrete and carpets, to increasing sediment and phosphorus levels and introducing toxic chemicals such as cyanide, chlorine or ammonia in our streams and rivers.
The following tips can help you choose the best deicing product for your home and the environment.
Check the Label
The table below provides a summary of the pros and cons of the various main ingredients of common deicing products. Check the package label closely to see what you are buying. Experts recommend using calcium chloride over sodium chloride (rock salt).
| Main Ingredient on Label | Temperature It Works Down to | Environmental Impacts |
|---|---|---|
| Calcium Magnesium Acetate (CMA) | 22°F to 25°F |
(+) Less toxic |
| Calcium Chloride (CaCl) | -25°F | (+) Can use lower doses (+) No cyanide (-) Chloride impact |
| Urea (Fertilizer) | 20°F to 25°F |
(+) Less corrosion (-) Adds needless nutrients |
| Sand | No melting effect | (-) Accumulates in streets and streams as sediment (-) Forms microparticles that become airborne and pollute the air. Micro particles are breathable and can affect people with respiratory problems. |
| Sodium Chloride (NaCl), aka rock salt | 15°F | (-) Contains cyanide (-) Chloride impact |
Avoid Kitty Litter and Ashes
Although these products are environmentally friendly, they aren't very effective. While they provide some traction, they do not melt snow and ice. Also, they tend to become messy when it warms up, which often tracks in to the floors of your home. If traction is what you want, then stick with sand, which is much cheaper and easier to sweep up.
Know Your Salt Risk Zone
You wouldn't want to kill your favorite tree, shrub or grass, so check out the plants that grow within five or ten feet of your driveway and sidewalk (and the road, for that matter). The table below summarizes some of the salt sensitive plants that might be at risk. If you have salt-sensitive trees, shrubs or grasses in this zone, you should avoid any deicing product that contains chlorides (rock salt and calcium chloride), or use very small doses. You may want to use CMA as a safer alternative, or stick with sand for traction.
| Landscaping Areas | Species at Risk from Salting |
|---|---|
| Deciduous Trees | Tulip Polar Green Ash Hickory Red Maple Sugar Maple |
| Conifers | Balsam Fir White Pine Hemlock Norway Spruce |
| Shrubs | Dogwood Redbud Hawthorn Rose Spirea |
| Grasses | Kentucky Bluegrass Red Fescue |
Avoid Products that Contain Urea
Some folks recommend the use of urea as a safer alternative to more common deicing products, arguing that it does not contain chlorides and, as a form of nitrogen, will help fertilize your yard when it washes off. In reality, urea-based deicing products are a poor choice. To begin with, urea is fairly expensive and performs poorly when temperatures drop below 20°F. More importantly, the application rate for urea during a single deicing is ten times greater than that needed to fertilize the same area of your yard. Of course, very little of the urea will actually get to your lawn, but will end up washing into the street and storm drain. Given that nitrogen is a major problem for our waterways, it doesn't make sense to use nitrogen-based products, such as those containing urea, for deicing.
Apply Salt Early, but Sparingly
Remember that "A little salt goes a long way." The recommended application rate for rock salt is about a handful per square yard treated (after you have scraped as much ice and snow as possible). Using more salt than this won't speed up the melting process. Even less salt is needed if you are using calcium chloride (about a handful for every three square yards treated - or about the area of a single bed). If you have a choice, pick calcium chloride over sodium chloride. Calcium chloride works at much lower temperatures and is applied at a much lower rate.
Shovel Early and Often
When it comes to snow removal, there is no substitute for muscle and elbow grease. Deicers work best when there is only a thin layer of snow or ice that must be melted. Get out the snow shovel and move as much snow as you can during the storm. A flat hoe can also help to scrape ice off the surface before any deicers are applied. Be careful when chopping the ice build-up that you don't damage your sidewalk.
Additional Tips
- After ice/pavement bond is broken, remove the remaining slush by shoveling.
- Limit access to your home to one entrance. For every doorway that is not used, there will be less deicer running into the catch basin in your street.