Reducing sand and salt use on Minnetonka roads
Over the past few winters, the city of Minnetonka has changed the way it controls ice on city streets. Read on for more information about the city’s new ice-control regimen.
Is sand still used by the city?
About four years ago, the city virtually eliminated the use of sand in its daily winter road maintenance operations, for a couple of reasons. First, while sand can help provide traction over existing ice, it does not actually melt ice or prevent its formation. Second, much of the sand applied to streets, parking lots, and sidewalks eventually washes into the nearest waterway, where it can fill wetlands, lakes, and creeks, or obstruct the flow of water through storm sewers. The city still keeps a small amount of sand on hand for instances when immediate traction is needed (such as ice storms) or when temperatures are too low for salt to be effective.
What are those sticky stripes on the street?
Right before it snows, residents may notice sticky lines on the street. This is an anti-icing solution containing magnesium chloride (MgCl2), which the city applies to most major streets just before a predicted snowfall. The “stickiness” is actually from corn syrup used in the solution. Anti-icing prevents snow from bonding with the pavement which in turn helps reduce ice formation and facilitates removal by the snow plows. Anti-icing solution also helps reduce the total amount of salt needed to keep our roadways clear.
What’s the white residue on the streets after the snow has melted?
The white residue is dried salt solution and may remain on the roadway for several days after the ice and snow have melted. It is not the result of increased salt use but rather an increase in the amount of salt that remains in the street. The city pre-treats its dry salt with a magnesium chloride solution before applying it to the road, which help the salt adhere to the pavement. This also increases the effectiveness of the dry salt by providing the moisture that is needed to melt the ice and by lowering the temperature at which the salts will work. Because the residue left behind is temporarily bonded to the pavement, it can also help prevent ice formation during the next snowfall and can reduce the need for additional applications. Without pre-treatment, you likely wouldn’t see the residue on the street, but there would be more salt by the side of the road or in the adjacent vegetation.
I heard that salt use can negatively affect natural resources. In what other ways is the city reducing the use of salt?
It’s true that chlorides from road salts accumulate in the environment over time and can have long-term negative effects on natural resources. While anti-icing and pre-treatment have resulted in large reductions of salt use on Minnetonka roads, the city has taken additional steps to reduce salt use. Those steps include calibrating equipment, installing applicator controls that adjust according to the speed of the truck, and measuring pavement temperature to determine the correct amount of salt to apply and avoid salt waste. In addition, the city applies most of its road salt after the snow plows have finished their first pass so the salt isn’t plowed right off the street.
How you can help
If possible, avoid using salt, but if safety concerns require you to control ice on your drive or walkways, follow these tips to help minimize salt use.
- Remove snow from paved surfaces as soon as possible, since most ice is formed by the pressure of foot and vehicle traffic. Remember that city plows usually make two passes to clear the width of the road; thus, you may want to wait for the second pass before you clear areas by the street or note that you may need to clear them twice.
- Considering using non-chloride salts or deicers to help prevent natural resource impacts. Non-chloride deicers have been effective in the Minnetonka City Hall parking lot and have helped prevent damage to the plantings in the adjacent rain gardens.
- Apply liquid salts or dissolve rock salt in a brine solution rather than applying dry salt. Salt will not melt ice until it is dissolved in a liquid.
- Apply salts to the upslope side of the pavement and allow it to flow across the ice rather than covering the entire surface. Products applied on the lower edge are often wasted.
- Don’t apply salt if the pavement temperature is too low. Rock salt is generally not very effective below 15 degrees F and most other salt blends are rarely effective below 0 to -5 degrees F.
- Use salt-tolerant vegetation adjacent to paved surfaces if you have problems with salt damage. Salt-tolerant plants and seed mixes are available at most nurseries.
Remember, when it comes to salt, more is not better! If it isn’t melting, adding more salt likely won’t melt the ice any faster. Applying too much salt can actually reduce the ability of the salt to melt the ice.