Why Salt should be stored Undercover
Although salt (sodium chloride) is a valuable material for snow and ice control, its use also causes some harmful side effects. Salt runoff and wind-carried spray may damage or kill plants and trees. Water supplies, especially those from shallow wells within 40 feet of a roadway, may be polluted by excessive salt content. Corrosion damage to motor vehicles is another obvious harmful side effect of salt use.
Close control of salt spreading to avoid excessive application will not only save maintenance funds but will also minimize these harmful side effects. It may also be desirable to use ditching and storm drains to alter present runoff patterns to reduce contamination of wells and roadside vegetation. If this water can flow directly and quickly to reasonably sized streams or rivers, this damage can be minimized.
In addition to roadway runoff, leaching of stockpiles also can cause salt pollution problems. Proper storage facilities and control of runoff can minimize the problem. That is why the Maine Legislature enacted the storage facility program in 1987.
Because shallow wells, and maybe deep wells, can be polluted by salt, it is possible that a municipality could face unexpected expenses in providing fresh water or drilling new wells for certain buildings. A municipality should be aware of State law Title 23 MRSA 3659 on the "protection of private water supplies". This law details the procedure for handling well damage claims.
Q. Why should a public works agency construct bulk salt storage facilities?
A. There are three answers ----- economy, availability and convenience.
Bulk salt is the most economical deicing material available.
Salt never loses its ice melting power no matter how long it is stored or how old it is. Salt is already millions of years old when it is mined. Each year thousands of tons of salt are stored and carried over to be used the next year. It is just as effective as though freshly mined or harvested. Neither is there any loss to moisture from the air if salt is stored properly. Salt does not absorb moisture until the humidity exceeds 76 %. Moisture that is absorbed will later evaporate, but there may be a thin crusting on the surface of the stockpile that is easily broken up.
Salt, however, can be lost to precipitation. Stockpiles, whether large or small, should not be left exposed to the elements. A permanent under-roof storage facility is best for protecting salt. If this is not possible, then outside piles should be built on impermeable bituminous pads and covered with one of the many types of temporary covering materials, such as tarpaulin, polyethylene, polyurethane or hypalon. Other waterproofing products may be available too.
There are several reasons why salt should be stored in a roofed enclosure.
- Salt stored in an outdoor stockpile, if not properly covered and if continuously exposed to moisture, will become lumpy or frozen and difficult to handle and use. These chunks can get discarded and "lost" by some individuals.
- Inside storage also eliminates the loss of salt dissolved and washed away by precipitation.
- Wet and caked or lumpy salt is harder to handle with loaders and to move through spreaders.
- Workers who must climb up onto a truck in the cold and dark or dislodge chunks on a belt or screen risk injuries and worker compensation claims.
- Salt stored inside is easier to load and spread. It’s dry and flows very well. Talk to any operator of a storage building and they would never go back to outside storage.
- Inside storage eliminates the possibility of contaminating streams, wells or groundwater with salt runoff.
- Inside storage "contains" the pile whereas an outside pile tends to "spread" across a property.
- Inside storage reduces unlimited access to a pile from citizens or private contractors.
- Ultimately, less money is spent on salt due to better control.
- if left exposed to weather, anti-caking agents can be washed from the outer layer of salt.
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