Farm Horizons, October 2014
Once an icon of rural architecture, many concrete silos are being removed or repurposed
By Tara Mathews
Cement stave silos have towered over the Minnesota landscape since 1905, and at one point were the most commonly-built silo type in the state.
Recent trends toward bunker or flat-style storage has left these iconic landmarks in the dust.
Many landowners repurpose the staves for landscaping, some convert their silo for dry grain storage, and a few remodel or repair the silo for its originally intended purpose.
“Out of more than 4,000 dairy farms in the state, probably about 2,000 still have concrete stave silos in use for high-moisture silage,” Hanson Silo Company Director of Business Development Mike Hanson stated.
That number is a drastic drop from the nearly 36,000 silos that were in use in the state less than 90 years ago.
Hanson Silo Company of Lake Lillian has built about five new concrete stave silos this year, which cost about $35,000 each, according to Hanson.
“The repair side has been quite busy this month, also,” he added. “But we only rebuilt one this year.”
There are a few different methods for demolishing concrete stave silos; some companies will pull from the top; some push from the bottom; and some pull on the metal bands that stabilize and help hold the staves in place.
“We can take them down either way, from the top or bottom,” Hanson commented.
“It’s like tipping a tree, it depends on the area and the structure,” Jay Rickert of Rickert Excavating said.
“Sometimes, we just use a sledge hammer,” he added.
How the material is dealt with after demolition varies, as well.
Rickert removes the staves from the work site and brings the material to Knife River Corporation in Glencoe or Hutchinson, where the concrete is broken down and recycled. He then fills the area where the silo once stood with dirt.
“When we finish, it looks like there was never anything there,” Rickert commented.
Hanson Silo Company does not remove the materials after the silo has been knocked down.
“We just knock it down and it’s up to the owner to clean it up,” Hanson noted.
The price for concrete stave silo demolition varies between $1,000 and $1,500 depending on the demolition company, the silo, and what is done with materials.
When a cement stave silo is torn down, the staves can be used for many landscaping purposes, the most common of which is sidewalks.
Many homes have concrete stave sidewalks leading to their door, barn, garage, or patio.
Other purposes for the staves can be patio block, retaining walls, garden borders, plant stands, and other landscaping-type applications.
The difficulty is, one never knows how many staves will escape the demolition in a solid, uncracked piece.
Another obstacle faced with repurposing staves is finding staves with the identical shape and size. Silos were made by many companies, and each company used a distributor of their choice. Staves can be slightly different, depending on the manufacturer.
Remodeling or repairing concrete silos
There are a handful of companies in the extended area that do silo repair or remodeling. Generally, the top or roof and plastering are where repairs are needed.
A new top for a silo will cost about $4,000, and can be done fairly quickly, according to Hanson.
Replastering, which involves spraying plaster on the inside of the silo to reseal it, will cost about $3,000, he added.
Silos converted for dry grain will usually need replastering to seal out moisture.
Converting to dry grain storage
It is possible to convert silos once used for haylage, silage, or high-moisture grain to dry grain storage, according to University of Minnesota Extension Office Engineer Bill Wilcke.
There are a few steps to take and items to consider before converting:
• Make sure the walls will withstand the pressure of dry grain. Filling dry grain to a depth 15 feet less than the maximum silage amount will exert the same amount of pressure on the silo walls as silage, according Wilcke.
• Make sure the silo is watertight. Check the roof and sidewalls for leaks, and make any necessary repairs before filling with dry grain.
• Develop a plan for filling. Getting the grain into the silo can be one of the most difficult obstacles, according to Wilcke. Silage blowers cause too much impact for dry grain, and most transport augers won’t reach the top of silos. The extension office recommends using pneumatic grain conveyors, which are slow and require a lot of power, but will get the dry grain up to the top of a silo with little damage.
• Install aeration equipment. Providing aeration can prevent insect activity, reduce mold, and prevent moisture migration.
• Make sure grain is dry enough for storage. Corn that will be fed in winter months can be stored at 18 percent moisture, whereas corn being stored into spring should be no more than 15 percent moisture. Corn that will be stored into summer should not exceed 14 percent moisture, and no more than 13 percent if the intention is to store for a full year or more. Small grains should be stored at about 13 percent moisture. Soybeans that will be stored into the following summer should be about 13 percent moisture, and if storing for a year or more, should not exceed 11 percent moisture.
• Upload from the center. Grain piled higher on one side will cause uneven wall pressure and can lead to structural damage.
“In some cases, silos are not in a convenient location for dry grain storage, or it turns out that it would be cheaper to build a new metal grain bin rather than convert an old silo,” Wilcke stated. “But in many other cases, silo conversion is relatively simple and can provide economical dry grain storage.”