By Dylan Deprey
As usual, Mother Nature has made this winter an interesting one. Whereas last year snow was a sight for sore eyes at the end of December, this winter was another story. With back-to-back snowstorms, day’s worth of rain and frigid temperatures to follow, the roadways have stayed fairly icy.
With all of the natural elements to transform I-43 into an Olympic car-slalom, plows and salt trucks have worked day and night to keep the roads as clear as possible.
Although sodium chloride and calcium chloride, otherwise known as road salt, have been the traditional de-icing method for years, it may pose a threat to Milwaukee’s waterways.
Chloride is soluble, so once dissolved into the melting snow and ice, whether it is a half a weeks’ worth of rain or sunny days following, there is the possibility for it to flow down storm drains and into waterways.
According to the Milwaukee Riverkeepers high levels of chloride in the waterways have the potential to instantly kill fish and aquatic life, known as acute toxicity. There is also the possibility for chronic toxicity, where lower levels of chloride with longer periods of exposure negatively affect an aquatic ecosystem.
USGS Wisconsin Water Science Center Research Hydrologist Steven Corsi conducted initial in chloride concentration research in 2014. Research found that the chloride levels increased 84 percent of the urban streams analyzed.
In the study, Corsi added that the most surprising part was that Chloride concentrations appeared to be increasing more rapidly than the increase in pavement that required deicing. He gave said increased rate in salt use, baseline conditions increased over time, or because of heavy snowfall.
Over the next several months the Milwaukee Riverkeepers will measure the chloride concentrations in Milwaukee’s waterways through their volunteer road salt monitoring program.
Volunteers and Riverkeeper’s staff will take water samples 48 hours after snow and melting events throughout Milwaukee.
“We do this because basically it is the time we expect the chloride levels to be the highest due to high road salt levels, and we identify when it is at its most dangerous level for wildlife,” said Zac Driscoll is a Water Quality Specialist at Milwaukee Riverkeeper.
He said that two water quality samples would be conducted. The first is an onsite measure of specific conductance (how conductive the water is), which correlates with high amounts of road salt. The other will be tested for chloride at the Wisconsin State Lab of Hygiene.
In the study, Corsi offered solutions to reducing salt which included: pre-wetting pavement with a brine and more effective plow designs.
According to the City of Milwaukee’s Department of Public Works the city has applied some of the solutions. General ice control (GIC) is the most common operation, and sends out 90 salt trucks citywide.
The cities’ truck mounted salt spreaders adjust the salt spread based on changes in the speed to evenly apply in urban stop and go traffic. When the temperature drops below 24 degrees, Liquid calcium chloride is added to road salt to make it more effective.
The city follows a sensible salting policy where salt is applied only where needed and in amounts appropriate for conditions. Salt may be applied only to the main streets, or only to bridges, hill stops, major intersections or slippery spots
While the Milwaukee Riverkeeper and its growing list of volunteers tests the river, Driscoll said that there are some ways people at home can reduce their road salt use.
“The main thing is to shovel early and shovel often,” Driscoll said.
“The earlier you get out there the less likely it is to pile up and turn into ice, so if you get it early on you eliminate salt completely.”