Overland Park, Kansas (population 173,000), sometimes uses a liquid pre-wetting agent to increase the effectiveness of road salt used for snow- and ice-control operations. The main product that has been typically used for this is liquid calcium chloride. Although it has been a proven material for the city, it is highly corrosive to its snowplow trucks and infrastructure.

A few years ago, Maintenance Supervisor Cathy Wilson initiated a trial use of a product that contained a mixture of magnesium chloride and the juice byproduct of sugar beet processing. The product was often referred to as “beet juice.”

The city’s interest in using this mixture was its advertised benefits of being less corrosive and its potential for allowing a reduced amount of salt to be applied to city streets. Both of these attributes also tied into the city’s desire to be more environmentally friendly.

Storage Issues

While results from the use trial of this type of product showed that it worked as an effective pre-wetting agent, public works staff did not find quantifiable evidence that it reduced the amount of salt usage. There also was a learning curve for storing the material.

Since the product contains sugar carbohydrates, staff learned that in certain cases these suspended hydrocarbon chains can settle out and this settlement requires periodic mixing in the bulk storage tanks. Periodic mixing of the liquid does eliminate filters in the snowplow truck’s pre-wetting system from getting clogged.

The beet juice product was stored in temporary plastic agriculture tanks and some rather simple modifications were made to accommodate the need for mixing it. The mixing was done by adding a re-circulating pump and piping that would draw liquid from the bottom of the tank and mix it with material at the top.

Staff members decided, however, that long-term use of the beet juice would likely require construction of a more dedicated tank system. Existing storage tanks the city uses for calcium chloride do not have re-circulating pumps, meaning any permanent move to using beet juice would require added construction costs for a new storage system.

Another Alternative

In the end, while staff members did not find specific points of reason on why not to use the product, they also didn’t find the economic benefits to supplant it as the city’s sole pre-wetting material. During the winter of 2012, however, the city decided to  switch from calcium chloride to an all-magnesium chloride solution.

Magnesium chloride was an additive the city’s supplier of beet juice offered and something it advertised as being a less corrosive substance than calcium chloride. After researching the potential cost and benefits of magnesium chloride, street maintenance staff decided to do a full-scale transition from calcium chloride.

Some factors staff assessed  in making this decision was magnesium’s similarities to calcium in terms of price, method of application, storage requirements, and being substantially less corrosive. With less corrosiveness, however, comes less reactivity to generate heat at low temperatures.

This arguably makes magnesium chloride less able to be used as a road salt pre-wetting agent at the same low temperatures as calcium chloride. In the Overland Park area where winter temperatures are more routinely on the milder side, staff felt the potential performance differences between magnesium and calcium chloride would be manageable.

At this time, no further testing or use of the beet juice product is planned; however, the city continues to keep the door open on its exploration for environmentally friendly snow- and ice-control chemicals.

J. Richard Profaizer, P.E., is manager, Maintenance Division, Public Works, Overland Park, Kansas (Rich.Profaizer@opkansas.org).