Snow Removal Challenges and Solutions
You’re not just clearing snow and melting ice—you’re providing for people’s safety. Do your job effectively, or you could wind up in court.
Snow removal from parking lots, roadways and sidewalks is a major responsibility for ground managers. Our customers expect a safe environment and are not willing to tolerate inconveniences. At the same time, we are often challenged with limited budgets and possible negative impacts of the materials used in snow removal. Concerns for safety and the liability implications of snow removal provide additional challenges.
Current developments in materials and methods add even more complexities to the grounds manager’s responsibilities. New chemicals and combinations of chemicals are now available that offer the promise of reduced environmental impacts and improved efficiency.
Managing liability and accident claims is an ongoing responsibility for ground managers. Legal liability often hinges on your ability to demonstrate that snow-removal operations were conducted in a reasonable manner. It is not usually required that dry clear pavement conditions be provided under all circumstances. Obviously, during a storm, some amount of snow and ice accumulation is inevitable. The key factor to an effective defense is to be able to establish that snow-removal operations were conducted according to plan.
Reasonable and effective snow-removal practices often depend on the timeliness of response and how well you clean up the area. You should coordinate with property owners to assure that snow-removal operations are completed in a timely manner. Periodic inspection of the property is particularly helpful in spotting slippery conditions. I highly recommend that your employees who are responsible for property inspection be empowered to take action to deal with spot problems immediately.
Snow storage areas also deserve special attention. As snow melts, the melt water should not drain across driving and walking areas before reaching storm sewers or ditches. This snowmelt can refreeze at night and cause slippery conditions.
Remember to document your routine inspections. If you are cited in a liability claim, this documentation can provide valuable proof of your good snow-removal practices. Photographs of any accident sites are also extremely helpful. Details on exact pavement conditions often become difficult to re-establish months and years after the accident.
Another liability problem area can develop when you have personnel maintaining sidewalks, and someone else’s crew is removing snow from the parking lanes and driveways. It is not uncommon to plow snow onto the sidewalk and then have sidewalk shovelers push the snow back into the driveway, or vice versa. This results in less than total clean-up and leaves open the possibly of melting and refreezing.
Plowing and hand removal have always been major components of snow-removal operations. They continue to be the most cost-effective snow removal techniques in many situations, especially when combined with effective use of chemicals. An effective mix of plowing, shoveling and chemical applications continues to provide the best combination for effective snow removal.
Plowing and shoveling can remove large volumes of snow as long as the snow is fresh and has not bonded to the pavement. When the snowstorm gets ahead of plowing operations, the snow has an opportunity to bond to the pavement or sidewalk. This bond is extremely strong and prevents efficient snow removal. The most effective use of deicing chemicals is an early application that prevents this bond from forming. The objective of an application of deicing chemical is not to melt all of the snow and ice, but rather prevent it from bonding to the pavement. This allows time for normal plowing and shoveling operations to remove the snow throughout the storm.
Chemicals are normally required to clear pavements shortly after a snow storm. Salt is the most commonly used deicing chemical and remains a very effective tool. At 30°F (pavement temperature), 1 pound of salt will melt more than 40 pounds of ice. However, at 20°F, 1 pound of salt will melt only 8 pounds of ice. Salt can still be effective at lower temperatures, but significantly more material is required to accomplish the same effect. Salt continues to melt ice down to –6°F. However, when the pavement temperatures get much below 15°F, the effectiveness is significantly reduced.
Salt works relatively fast at warmer pavement temperatures. At 25°F, salt will melt a thin layer of ice in about 7 minutes. However, when the temperature drops to 10°F, it can take up to an hour to accomplish the same result. These facts lead most managers to consider limiting the application of salt when pavement temperatures are in the range of 15° to 20°F and falling.
Alternative chemicals become more effective when temperatures drop below 15°F. Calcium chloride and magnesium chloride have long served as effective deicers for colder temperatures. They can be effectively used in temperatures well below zero. Because these materials are more costly than salt, managers often mix the calcium chloride or magnesium chloride with salt to provide a blend that can be even more effective at lower temperatures.
Fortunately, most snowstorms occur at temperatures in the mid-20s. Early applications of deicing chemicals at warmer temperatures allow efficient removal of the snow during cleanup. If you delay, it may not only cause snow pack conditions, but while temperatures fall after the storm, it can further reduce the effectiveness of chemicals. Nothing can improve the efficiency of a snow-removal operation more than timely application of chemicals and plowing. While this often creates the need for overtime expenditures, these costs can be small in comparison to the hours you’ll spend plowing and applying chemicals after the storm.
Several relatively new chemicals are being employed to assist in snow removal. Ice Ban is a product derived from the food-processing industry. It is a somewhat sticky, brown-colored liquid. It is most often combined with other chemicals such as magnesium chloride, and used to either pre-wet salt or for anti-icing. Tests indicate that Ice Ban, when mixed with traditional de-icing chemicals, significantly reduces the corrosiveness of these materials. This desirable effect is leading to increased use of this material. However, it also has been reported that tracking into buildings increases with Ice ban. The material can be cleaned from floor surfaces with cold water.
Pre-wetting salt with liquid chemicals is a practice rapidly growing in popularity. Because salt must first be dissolved into a brine before it can melt ice, the pre-wetting helps to “jump start” the salt. Wetted salt is also less likely to bounce and roll off a pavement surface, which allows you to reduce the application rates. The liquid is applied at 8 to 10 gallons per ton of salt. A wide range of liquid chemicals have been used to pre-wet salt. They include dissolved salt, calcium chloride, magnesium chloride and Ice Ban.
Pre-wetting the salt as it is applied is the most effective method, but this requires specialized tanks and “on-board” spray equipment. Salt also can be pre-wetted at the shop as it is loaded into the truck. Some managers even find it effective to pre-treat the salt pile. However, this latter approach means all of your salt will be pre-treated even under conditions where pre-wetting may not be necessary, such as warm temperatures or slushy pavements.
Several special chemicals are available in areas where concern exists for sensitive environmental resources. For example, corrosion to reinforced steel in parking garages is a significant issue. Calcium magnesium acetate (CMA) has been available for many years. It has been thoroughly tested by the Federal Highway Administration and is non-corrosive. Potassium acetate is a liquid that is effective in cold temperatures as well as being non-corrosive. Corrosion-inhibiting additives are also available for liquid calcium chloride and magnesium chloride. These products are used in tandem with Ice ban for corrosion reduction.
Common fertilizer products such as urea and potassium chloride also have historically been used for de-icing. Unfortunately, tests indicate that these products are not effective deiciers, especially when temperatures fall below 25°F. In addition, the runoff of these materials into surface waters may be highly undesirable in areas sensitive to nutrient-laden runoff.
Abrasives, such as sand, are another effective tool in snow-removal operations. When pavements reach temperatures where salt is no longer affective, abrasives can help deal with slippery conditions. Unfortunately, abrasives do not melt ice, and, eventually, plowing and chemical applications will likely be required for final snow removal. And using abrasives often requires post-storm cleanup, which adds to your total job cost.
A small amount of salt is often mixed with an abrasive to enhance its performance during freezing temperatures. Tests have shown that 50 to 100 pounds of salt per cubic yard of sand is normally effective. Some managers like to mix more salt with the sand. While this may prove effective during some storm conditions, it can become a wasteful practice.
Keep in mind that salt is used to melt snow and ice, and sand is used to provide traction under conditions when the pavement cannot be cleared. These materials accomplish different tasks and mixing them together does not change that. It is a good idea to have abrasives available to deal with slippery conditions when temperatures prevent effective chemical melting.
A relatively new technique for anti-icing is being used in areas where a higher level of service is desired. Anti-icing is applied as a liquid chemical to the pavement before the storm begins. Relatively light applications are made in the range of 25 to 50 gallons per lane-mile. This small amount of chemical residue remains in place for many hours or even days. When the storm arrives, the chemical works to prevent the initial bonding of snow to the pavement. During heavy snow or freezing rain conditions, you must then immediately follow-up with plowing and conventional deicing.
Evaluate your options
You have many options when it comes to materials and procedures for your snow-removal operations. However, selecting the most effective chemicals and procedures requires you to become familiar with them. Vendors can be excellent source of information—especially when you use their information in conjunction with training sessions provided by universities and trade associations. To learn how and when to use these materials appropriately before implementing broad-scale applications, I highly recommend trials on a small-scale basis.
Effective snow-removal operations require planning and training. All of your employees should have the opportunity for a refresher training session prior to activation of snow removal operations. Trained, capable, motivated employees will always remain one the keys to effective snow removal. Upgrades in equipment and appropriate use of new chemicals can allow you to meet your customers’ needs in a cost-effective manner.
Don Walker is professor of engineering at the University of Wisconsin—Madison.
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