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Solving freezing rain

By:
  • Dale Keep
- Posted: April 29, 2016
Different events can impact how contractors use labor, equipment and materials (LEM) to effectively and efficiently deal with the storm. This is especially true when freezing rain is involved. We all know that some storm events are tougher to handle than others, but a freezing rainstorm of even medium intensity and duration has to be the toughest. Generally, freezing rainstorm events represent receiving water over a short period of time and quickly occurring ice buildup. Because of these storm characteristics, applications of most any deicer and/or grit generally are rendered ineffective very quickly. To address how to best manage or approach a storm, one must first look at the contract and the level of service (LOS).  

Contract and LOS
How to best manage LEM is easy on a high level. It’s simple - do the right thing, at the right time, in the right way and in the right quantity. Nothing to it! But one major detail is missing - what are you trying to accomplish? 

Is the goal to use minimal deicers? Keep the pavement bare and wet at all times? Bare and wet by 7 a.m.? Each goal as defined in the contract can demand a different approach to best manage LEM to accomplish it. The only way to determine how to best manage LEM when a freezing rainstorm is coming is to have a plan in mind before or as soon as it starts.
 
The customers’ expectations or service goals should be clearly expressed in the LOS portion of the contract. I’ve said before, do not sign a contract until you have fully read and understand it. Does the contract address “what if” scenarios like a long-duration heavy buildup of freezing rain? In reality, with a storm of this type, most likely little can be done until it is over. 

With freezing rain, the answer is probably not as much technical as it is legal. What does the contract say? What did you agree to do? Do you have any options, and if you do something wise technically or realistically speaking, what risks are you taking legally?  

Freezing rain
Freezing rain is rain that hits a surface with a temperature below freezing, causing the formation of ice since the rain freezes shortly after contact. Storms range in severity from light to severe. The real difference between them for the sake of this article is the amount of ice created by the event. 

For example, assume an ice storm such as the one that occurred in northern Idaho, Jan. 1-3, 1961. This storm set a record for thickest recorded ice accumulation from a single storm in the United States, at up to 8 inches. Historical weather data reveals that a combination of fog, sporadic freezing rain and subfreezing surface temperatures led to the heavier ice accretions. 

Bear in mind that ice created by freezing rain at a depth as low as 0.012 inches deep is just as slick as ice created by freezing rain at a depth of 0.25 inches or more, even though the 0.25 is nearly 21 times as much ice and would require nearly 21 times as much deicer to melt it. Also note that the “thin ice” can actually be more dangerous since it can be invisible or appear wet on many surfaces.  

For this article, the terms light, medium and heavy are used as the three types of freezing rainstorms for comparison.  Information presented is from a technical winter operations standpoint only. 

Light
The term “light” represents a small amount of moisture predicted and received. The ice created is very thin yet dangerous but normally melts easily since temperatures during freezing rain events are typically favorable for better deicer performance. General treatment steps:

Step 1: Anti-ice ahead of the storm. With a light storm forecasted, the application rate should be enough to keep areas free of ice during the entire event. 

Step 2: Monitor and reapply as necessary.

Step 3:
Remember that after the event passes, clearing skies and colder temperatures may follow. Under such conditions, a deicer reapplication may be required to prevent refreeze. 

Medium
Medium is between light and heavy in moisture forecasted and received, and the depth of ice created. This can be the most difficult freezing rainstorm to manage but the easiest to write about. The answer to the correct approach to this storm is largely based on your operations and contract specifics. By considering these two things, you can determine if it is a light or heavy storm. Suggested treatment steps:

Step 1: Review the weather forecast and LEM inventory.  

Step 2: Decide your approach (treatment as a light or heavy storm).

Step 3: Anti-ice ahead of the storm, noting the surface temperature at the time of application. The application rate should be small. The goal is to have something under the ice when the storm ends.  

Step 4: Review new forecasts, your operations and results achieved often to see if you need to change your approach. Be realistic and flexible. 

Step 5: Follow the general steps for either the light or heavy storm events as appropriate. 

Heavy
“Heavy” means a large amount of moisture predicted and received. Obviously the ice created in a storm of this magnitude is not going to be invisible or thin, but it is going to be very dangerous. With thick ice, its removal with deicer melting alone is probably not the answer. Suggested treatment steps:

Step 1: Accept the fact that with a storm of heavy magnitude it is not going to be possible to stay ahead of it. Trying to do so often means cleaning out the salt supply and then not having any deicer when the storm ends.

Step 2: Anti-ice ahead of the storm, noting the surface temperature at the time of application. The application rate should be small since the goal is to have deicer residual under the ice when the storm ends.  

Step 3: Now for the hardest step: Do nothing until the storm is over.

Step 4: After the storm has subsided, apply deicer. The goal is to penetrate the ice and get the solid deicer to the bottom to mix with the residual from the earlier application and break the bond. 

Step 5: Plow as much as possible and reapply small amounts of deicer as necessary to remove the remainder. 

Step 6: Follow up and reapply as necessary, understanding that after the event passes, clearing and colder temperatures may occur, and a reapplication may be necessary to prevent refreeze. 

Conclusion
In any storm event, especially severe ones such as freezing rain, contract terms, LOS, customer expectations, reality and legal risks all must be considered when determining the best approach. Only you and your team can decide how to approach each storm, but it is imperative that these extreme storms and or temperatures be addressed with the customer before the contract is signed.  
 
Dale Keep owns Ice & Snow Technologies, a training and consulting company based in Walla Walla, WA. Email him at snowbusiness@grandviewmedia.com.
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