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Sidewalk Salt and Stormwater

Posted: February 10, 2014

We all know that it is very important to remove ice and snow from walkways to prevent injury. However, we often forget the damage that some of the materials we use to melt ice can do to plants and the environment.

For many years, we used rock salt to melt ice on roadways and sidewalks. Rock salt is the most common deicer available for those slippery sidewalks, driveways and steps. However, rock salt is very corrosive and is not good for the environment. It can weaken concrete and pollute our streams when it is carried into storm water. Encourage anyone using a deicer at your house to use as little as possible or purchase an alternative that does not harm the environment.

We have all seen the rusty bridges, guardrails and brown evergreen trees from using salt. Rock salt is sodium chloride. It is low cost and abundant. It will damage plants and can leach into the soil and affect the plant roots. Also, as salt melts the ice, the water solution runs into nearby storm drains or ditches. From there, salt can seep into groundwater or enter local lakes and streams. This excess salt poses a threat to fresh water ecosystems and fish.

According to the Maryland Cooperative Extension Fact Sheet 707, “Melting Ice Safely,” a better alternative to use is calcium magnesium acetate (CMA). It is a different from salt. As it comes in contact with snow and ice, it will give off heat so it is more effective than salt at low temperatures. The fact sheet, “Melting Ice Safely” is available on-line.

There are other materials that can be used to reduce the problem of slippery sidewalks. Some people will use sand, grit, sawdust, bird seed or cat littler to prevent slipping. While these may not be the best products, in some situations they are easier on the environment than other materials you can select from.

One material I would encourage you not to use is fertilizer and especially urea fertilizer. It will melt snow and ice, but the nitrogen gets carried off by the melting ice and snow and the nitrogen can end up in our waterways and eventually in the Chesapeake Bay. So do not use urea or other fertilizers, but purchase one of the other products that have been mentioned. 

Whichever material you choose to help you get rid of ice, remember that the purpose of a deicing material is to start the melting process so the ice will break up and can be shoveled off the sidewalk. Do not use the chemical deicer as your only way to get rid of the ice. You need to shovel too, once the deicer has done its job.