DEICING & TODAY’S CONTRACTOR
Providing a safe environment takes diligence and experience.
Snow contractors are finding that their customers have become more demanding of services to keep sites safe for pedestrian and vehicular traffic. After all, we are essentially “risk managers” for our customers benefit. Providing a safe environment takes diligence and experience. When it comes to providing deicing or anti-icing services, the uninformed and uneducated will not be able to properly address situations that arise on customers’ properties.
I have been in markets where customers will point out their white pavement after a storm and declare “my contractor did well.” What they fail to realize is their contractors over applied sodium chloride (salt) and wasted a whole pile of their money, not to mention added to the public’s perception that salt damages the environment. Over application of rock salt on parking lot surfaces is the main reason water tables become contaminated with salt. A bit of education for the contractor and the customer can go a long way to avoid these issues.
Proper distribution and proper understanding of the quantities required for effectiveness on properties we service is another problematic issue in our business. Some contractors still insist on telling customers they are applying a ton of salt per acre of pavement. For the most part, this is not really possible without some considerable effort.
Studies show as little as 100 pounds an acre is sufficient to effectively treat ice on pavement surfaces. However, contractor equipment cannot be calibrated this low, so we need to use something closer to 300-500 pounds per acre of pavement. Even this rate is often evidence of over application of rock salt.
Interestingly enough, a recent study completed by Snow Magazine shows 14% of the respondents to a survey about what they considered an acceptable quantity of salt per acre still believe one ton per acre is appropriate. 22% believe 500 lbs per acre is acceptable, while 40% said ½ to ¾ ton was acceptable. That means 76% still believe that over applying salt is an acceptable practice in our industry. I imagine that if I asked those contractors how they were charging for salting and deicing services the answer would be either “per ton” or “per pound”. It’s the only reason to justify those amounts.
Another issue prevalent in the industry is a lack of knowledge of how salt works. Sodium chloride is endothermic in nature. Salt, in and of itself, does not melt anything. It lowers the freezing point of water. Salt must react with moisture to go “into solution”. The resulting reaction with the ice lowers the freezing point. It does not generate any heat. Once the freezing point is lowered to a temperature that is lower than the pavement temperature, water results. Continued snowfall will dilute the concentration of salt that is in solution, effectively raising the freezing point of water so as to allow refreezing to occur.
On the other hand, calcium chloride generates heat when it interacts with moisture. This exothermic reaction is rather violent. In fact, the reaction can generate enough heat to allow the resulting water to evaporate quickly from the pavement or concrete surfaces. This is why you often see dry pavement a few hours after an application of calcium chloride on a sidewalk.
Contrary to popular belief, concrete spalling is not caused by rock salt. Concrete used in sidewalks is quite porous. Rock salt lowers the freezing point of water. The water permeates the concrete sidewalk and gets into the pores of the relatively fragile sidewalk concrete mix. When temperatures go down at night, this water freezes (in the pores) causing the concrete to crack and “pop” pieces of concrete. As such, the use of calcium chloride is preferred on sidewalks because it generates enough heat to foster evaporation of the resulting water. Water does not get a chance to settle into the pores in the concrete and thus, spalling does not have an opportunity to occur.
Salt, calcium chloride, mag chloride and other deicing agents are tools for snow contractors to use in fighting icy conditions on customer parking lots, road surfaces and sidewalks. As with all tools, proper use (as directed) will result in better results. Tools that are misused are often thought to be the cause of the problem. It is not the tool, but how it is used that creates desirable results. If one uses the deicing agent (tool) properly – more effective results will be obtained. Contractors and customers need to be educated as to how these tools work. A lack of education can create problems and false expectations of the results obtained.
When salt prices escalated a few years back due to shortages in supply, many began investigating possible additives to enhance the performance of rock salt. Many, many experiments were performed in an attempt to prolong residual effects of rock salt. Beet juice, derivatives of corn solids and various animal extracts were applied to salt piles as prices escalated seemingly out of control. Intense marketing campaigns have kept these additives alive and kicking. It is hard to argue with visual evidence put forth in marketing materials. However, widespread acceptance and use of such products is still an uphill battle in the marketplace.
All evidence confirms straight, untreated rock salt – good old NaCl – is still the least expensive and most desirable alternative when it comes to treating icy surfaces. Easy to obtain, easy to transport, fast acting at freezing temperatures, and the product of choice by the vast majority of snow fighters – both private and municipal. The escalating prices from a few years back, as a result of the shortage, have abated. While it is unlikely we will see a return to mid-nineties pricing structures – rock salt is still the best deal when it comes to the war on dangerous slippery surface conditions.
By J. Allin in the Snow Magazine