Wx and the City
* Our Latest Forecast: Showers Then Overnight Refreeze *
Many Washington-area residents have been applying deicing products over sidewalks and driveways last night and this morning. This is an important precaution to take to avoid accidents and injury. However, there are many products to choose from, and safe and effective ways of applying them. Here are some tips for choosing deicers and reducing environmental impact.
Experts recommend choosing calcium chloride over rock salt (sodium chloride). Calcium chloride costs more, but lasts longer -- it can be used in smaller amounts than rock salt. Also, it does not contain cyanide, an anti-caking chemical that can harm aquatic life. Calcium chloride is effective to about minus 25 degrees Fahrenheit; rock salt is effective to about 10-15 degrees Fahrenheit. Calcium Magnesium Acetate (CMA) is the safest choice overall, but costs much more.
Keep reading for more on choosing a deicer and usage tips...
Check out page 3 of this document (PDF) from the Center for Watershed Protection for an analysis of common deicers, their costs and their effects on the Chesapeake Bay watershed.
All road salts and sand can have a negative impact on the local environment by infiltrating into groundwater supplies, washing into nearby rivers and streams or harming vegetation. To reduce the impact, here are some tips to remember:
Before you apply a deicer, remove as much snow and ice as possible. Deicing products are most effective when they are applied to a thin layer of ice.
Apply early. Deicers are most effective and last the longest when applied before accumulation starts. (Remember this for the next storm.)
Follow directions carefully, and only apply as much as you need. A little goes a long way. About one handful of rock salt per square yard will do the trick; one handful of calcium chloride will treat about three square yards. Adding extra product won't speed up deicing.
Know your landscape. Road salts can harm trees and other woody plants that are intolerant to salts. If you use a deicer at home, leave a safe space around sensitive species (check out page 4 for a list of sensitive species).
Thanks to Earth Gauge for these tips.