Line 322: | Line 322: | ||
*It may be possible to use a lower rate in high traffic areas. Traffic tends to help mix and melt. | *It may be possible to use a lower rate in high traffic areas. Traffic tends to help mix and melt. | ||
*Store snow downhill from any salt storage areas. Avoid water running through salt storage. | *Store snow downhill from any salt storage areas. Avoid water running through salt storage. | ||
+ | |||
+ | ===Materials=== | ||
+ | All products have pros and cons. No one material is suitable for every condition. It is best to have a variety to choose from to select the one that works the best, with the least amount applied, in a specific situation. Understand the melting properties of the deicers; do not use the product without understanding how it works. | ||
+ | |||
+ | The best way to reduce impacts, save money and maintain customer satisfaction is to: | ||
+ | *Know what is in the product. | ||
+ | *Know the product’s practical melting range. | ||
+ | *Use it only when it will be effective. | ||
+ | *Use the minimum amount needed to get the job done. | ||
+ | *Seek out products that allow for smaller application rates. | ||
+ | |||
+ | ====Abrasives:==== | ||
+ | *Sand is an abrasive; it does not melt snow and ice. | ||
+ | *Abrasives provide traction on top of packed snow or ice. | ||
+ | *Abrasives and deicers typically work better alone, rather than together. | ||
+ | *A small amount of salt must be mixed in the sand to keep it from freezing in the pile (less than 10%). | ||
+ | |||
+ | ====Salts==== | ||
+ | *Sodium Chloride, Magnesium Chloride, Potassium Chloride and Calcium Chloride are all considered “salts.” | ||
+ | *Salt is a deicer; it will melt snow and ice. | ||
+ | *Salt lowers the freezing point of water from 32° F to a colder temperature. | ||
+ | *Salt must be dissolved to work; therefore, liquids act faster than solids. | ||
+ | *Salts have different melting characteristics, depending on the selection. | ||
+ | *Road salt (NaCl) is a granular product and is mined from the earth. | ||
+ | *Magnesium Chloride (MgCl2) and Calcium Chloride (CaCl2) can naturally occur as liquids. | ||
+ | *MgCl2 and CaCl2 are hygroscopic, drawing moisture from the air to the pavement. | ||
+ | *Salt brine (NaCl) is commonly used at a 23.3% concentration as this has the lowest freezing point and can be stored and handled down to -6°F. | ||
+ | |||
+ | ====Acetates:==== | ||
+ | *Acetates are chemically manufactured, not mined from the earth. | ||
+ | *Acetates are more expensive than chloride salts. | ||
+ | *Acetates are less corrosive than salts. | ||
+ | *They have a wide melting range, depending on the selection. | ||
+ | *They are not better or worse than chloride salts, they are different. | ||
+ | |||
+ | ====Plant-based additives==== | ||
+ | Corn, beet, molasses, or other organic additives are added to salt or salt brine to change its performance, though how they function as an ice melting agent is not well understood. Clear Roads (2015), a national resource consortium of state agencies, is studying this issue. | ||
+ | *Often have very low ice melt capacity. | ||
+ | *May be used to reduce corrosion. | ||
+ | *Are sticky and may help dry material stay on the surface longer. |
Start now—develop a maintenance policy or plan that guides winter operations. A little planning and communication up-front can help achieve better results throughout the season.
Our waters are threatened by contracts which are based on fees for material use. This encourages overuse of materials.
Reduce liability. Establish a maintenance policy and follow it.
Reduce risk by having a solid written winter maintenance policy and training program that utilizes best management practices. Schedule training for supervisors, staff, and customers.
The MPCA has three Smart Salting training classes available:
Check the MPCA website to find out about upcoming training opportunities.
Inspect storm drains in the fall. Remove obstructions such as leaves, sticks, and trash to prepare for the spring melt. Because storm drains lead to lakes, rivers, ponds, and wetlands, never use salt to open frozen storm drains. Salt used to thaw frozen drains harms aquatic life. Use non-chemical methods such as heat to open drains.
Poor drainage on the maintenance surfaces will result in icy surfaces and will increase the risk of safety problems. These areas cause the application of salt on non-snow event days in the winter. To remedy this, inventory the site and note drainage problems. Make a checklist so the professional or client can fix these drainage problems in the summer.
Examples of drainage problems:
Storm drains lead to the nearest lake, river, pond, or wetland. They do not go to a treatment plant.
The trend in winter maintenance is to use less material to accomplish the same results. Following this trend will reduce environmental impacts and save money. Below are listed a few tips, but there are many other innovations in the equipment area that can help to reduce application rates.
Calibration is an essential procedure to understand how much material will be discharged at a given setting. No matter how sophisticated or simple the operation, calibrate each piece of equipment in the fall of the year.
Calibration tells how much material will be applied at each setting.
If the equipment has different settings, it must be calibrated for each setting and for each product, as they all flow differently. It generally takes a team of two or three people to calibrate equipment efficiently.
Ground speed controlled spreaders are run by a computer in the cab and are tied to the speedometer and an auger or conveyor sensor in the rear of the truck. The application rate is set and the computer regulates the amount of salt discharged (regardless of the speed traveled) consistently. Most equipment used for winter maintenance of roads have ground speed controls. These are more effective and efficient systems than the manually controlled systems.
The equipment vendor will have specific calibration instructions for the operation based the type and brand of equipment. Contact them; it is in their best interest to provide instructions to calibrate and correct product use. This is the basic principle behind calibrating a ground speed controlled spreader:
Best bet: Contact manufacturer for calibration instructions.
Calibration allows accurate deicer use
Manual controlled spreaders fall into two categories. Those that have an auger or conveyor and those that are gravity fed. They operate by selecting a setting that changes the size of the discharge opening and/or the auger or conveyor speed. More or less salt may be discharged depending on the speed of application. Most parking lot and sidewalk spreaders fit into one of these two categories.
All good programs are based on calibration of equipment.
The basic principle behind calibrating an auger/conveyor spreader is to choose a setting, run the spreader for a timed interval, and weigh the discharge. Record the discharge and repeat for all settings. In the end, there will be data that tells the operator how much material will be delivered at each setting. With this information, the operator can choose the proper setting. Without this information, they have no guidance on which setting to use. Calibration is different for gravity fed spreaders. There is more detail on this in a few pages.
Apply wisely. The chemicals applied cannot be recovered.
Surfaces such as pervious asphalt, pervious concrete, and pervious pavers do not experience refreeze. All melted snow and ice travel to the storage layer below the surface. Salt is generally not needed on these surfaces and sand should be avoided.
Example: Step #1, blank calibration form
See the References and Resources section for a full size form to copy for calibration. This is how the empty form looks.(Keep a stack of these on a clipboard when ready to begin the calibration.)
Example: Step #2, calibration form filled out during calibration
Fill in the header information and column 2, the discharge weight per setting.
Example: Step #3, calibration form ready to put in truck for road application'
Back in the shop, do the calculations to fill in the rest of the blanks. Multiply the weight in column 2 with the multiplier in the top row. This provides the pounds per mile that needed to fill in the table.
Some fish species are affected by concentrations of less than 1000 ppm NaCl, about 1 to 1.5 tablespoons of salt in 5 gallons of water.
Example: Step #4, calibration form ready to zip tie to hand spreader or put in truck for parking lot application.
Divide by 63 to convert pounds per lane mile to pounds per 1,000 square feet. This is very useful for parking lot and sidewalk applications.
Snow Piles:
Improper storage of salts can lead to groundwater cantamination
Salt and Salt/Sand Piles:
Salt storage areas are often a source of groundwater contamination. To reduce risk, have a covered storage area on an impervious pad. Take measures to keep salt or salt brine from leaving storage area.
A common mistake is storing a salt pile downhill from a snow pile
Sand piles:
Prevent groundwater contamination. Do not locate storage areas near wells. Limestone regions with fissures and sinkholes are very prone to groundwater contamination, as are those with sandy soils.
Manual controlled spreaders fall into two categories. Those that have an auger or conveyor and those that are gravity fed. They operate by selecting a setting that changes the size of the discharge opening and/or the auger or conveyor speed. More or less salt may be discharged depending on the speed of application. Most parking lot and sidewalk spreaders fit into one of these two categories.
All good programs are based on calibration of equipment.
The basic principle behind calibrating an auger/conveyor spreader is to choose a setting, run the spreader for a timed interval, and weigh the discharge. Record the discharge and repeat for all settings. In the end, there will be data that tells the operator how much material will be delivered at each setting. With this information, the operator can choose the proper setting. Without this information, they have no guidance on which setting to use. Calibration is different for gravity fed spreaders. There is more detail on this in a few pages.
Apply wisely. The chemicals applied cannot be recovered.
Surfaces such as pervious asphalt, pervious concrete, and pervious pavers do not experience refreeze. All melted snow and ice travel to the storage layer below the surface. Salt is generally not needed on these surfaces and sand should be avoided.
Example: Step #1, blank calibration form
See the References and Resources section for a full size form to copy for calibration. This is how the empty form looks.(Keep a stack of these on a clipboard when ready to begin the calibration.)
Example: Step #2, calibration form filled out during calibration
Fill in the header information and column 2, the discharge weight per setting.
Example: Step #3, calibration form ready to put in truck for road application'
Back in the shop, do the calculations to fill in the rest of the blanks. Multiply the weight in column 2 with the multiplier in the top row. This provides the pounds per mile that needed to fill in the table.
Some fish species are affected by concentrations of less than 1000 ppm NaCl, about 1 to 1.5 tablespoons of salt in 5 gallons of water.
Example: Step #4, calibration form ready to zip tie to hand spreader or put in truck for parking lot application.
Divide by 63 to convert pounds per lane mile to pounds per 1,000 square feet. This is very useful for parking lot and sidewalk applications.
The amount of deicer needed is based on the size of the parking lot. Here are simple ways to calculate the area of the parking lot.
Ask the property owner for a scaled map of the facility to calculate areas.
Ask the property owner for the size of the area to be treated.
Measure the parking lot.
Use an internet mapping tool to calculate areas.
The area, or square feet, of a square or rectangle is:
Length (L) X Width (W)
The area, or square feet, of a circle is:
π r2 or 3.14 x (r x r) where r is half of the distance across the circle.
The area, or square feet, of a right triangle is:
Length (L) X Width (W) divided by 2
Measuring the area, along with knowing the pavement temperature, will allow the use of the application rate charts. This will help to reduce the amount of chemicals applied.
Snow Piles:
Improper storage of salts can lead to groundwater cantamination
Salt and Salt/Sand Piles:
Salt storage areas are often a source of groundwater contamination. To reduce risk, have a covered storage area on an impervious pad. Take measures to keep salt or salt brine from leaving storage area.
A common mistake is storing a salt pile downhill from a snow pile
Sand piles:
Prevent groundwater contamination. Do not locate storage areas near wells. Limestone regions with fissures and sinkholes are very prone to groundwater contamination, as are those with sandy soils.
Always remove snow prior to applying deicers. Plow, blow, or sweep first; the chances of refreeze diminish and slush build-up is minimized.
Salt only needs to melt 1/16 inch to prevent the bond between the pavement and the ice. Save money by applying salt before the ice bonds to the surface it doesn’t need to melt through the ice.
Steps are often the most over-salted area in all of winter maintenance. This overabundance of deicer causes damage to floors inside the building as salt and/or sand is tracked in. It causes problems outside of the building with deterioration of concrete and metal structures. Over applying deicer costs more money than necessary, pollutes the water, and does not provide any additional safety. The right amount of deicer and proper mechanical removal of snow and ice will yield better results.
A free short video for small site winter maintenance is available. It is designed for those that do winter maintenance of small sites such as stairs, curb cuts, and handicap ramps. The video is a visual instruction tool useful for those who apply granular deicer to small areas outside building entrances. It recommends:
To determine the amount of deicer needed for steps, stairs, and small sites:
Handheld spreaders and shakers, not scoops, should be used to apply deicer to steps and building entrances. This will save at least 50% of the salt normally used per winter without reducing the level of safety.
All products have pros and cons. No one material is suitable for every condition. It is best to have a variety to choose from to select the one that works the best, with the least amount applied, in a specific situation. Understand the melting properties of the deicers; do not use the product without understanding how it works.
The best way to reduce impacts, save money and maintain customer satisfaction is to:
Corn, beet, molasses, or other organic additives are added to salt or salt brine to change its performance, though how they function as an ice melting agent is not well understood. Clear Roads (2015), a national resource consortium of state agencies, is studying this issue.