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OSU Extension

College of Food, Agricultural, and Environmental Sciences

December 6, 2019 - 11:17am --

There are two primary risks associated with bunker silos and silage piles; falling from the top of the pile/bunker and second, a person or persons on the ground near the silo or pile being buried by a silage avalanche. Two factors that increase the risk of these accidents are complacency and weather conditions.

Within our dairy community here in Wayne County I have heard stories both about falls from the top of a bunker and about silage avalanches.  Thankfully, these types of accidents do not occur frequently.  However, as a result, over time, that risk is no longer in the forefront of our thoughts as we work around the bunker.  We can become distracted, our mind occupied with other thoughts and we lose some awareness of our surroundings and the potential for an accident.  As we get into cold weather, especially when combined with some wind chill and/or sleet/snow, these conditions create heightened concern from a safety awareness perspective.  When it is cold and windy, we tend to be less alert. We may not be as observant of our surroundings. The focus is on getting the job done so we can get some place warmer.  Sleet or snow create slippery conditions, certainly a concern for someone on top of a bunker or pile covered with plastic.  Snow might even mask the true edge of the pile.

Silage avalanches occur when a portion of the silage face breaks away from the pile and falls.  There is no way to predict when and where along the face an avalanche will occur.  Some bunker faces indicate a greater possibility or potential for an avalanche compared to others, but there are plenty of documented instances of silage avalanches from a bunker or pile that appeared stable and solid. The danger is being caught under the crushing force of an avalanche.  Besides the sheer weight, the force of impact is multiplied as the height of the fall increases.

Consider this example: most bunker silos and silage piles are packed to a density between 40 to 48 pounds per cubic foot on an as fed (moisture included) basis.  A silage avalanche involving two cubic yards of silage packed at a density of 44 pounds per cubic foot weighs more than a ton, 2376 pounds. This is not an extreme example. It is not hard to find stories of silage avalanches involving 10 or more tons of falling silage.  Regardless if it is one or ten tons, any weight falling from a 20-foot tall silage face versus a 10-foot silage face represents a significant increase in force.  Getting caught in an avalanche can result in bruises and broken bones if you are fortunate enough to survive, but the real tragedy is getting buried and dying by suffocation.

Assess the degree of safety risk associated with a silage pile by considering height of the silage, face management, and labor tasks.  The equipment that will be used to remove silage and   manage the silage face should be matched to the bunker silo or silage pile height.  Piles that are taller than equipment can reach usually have silage faces that are more uneven, and overhangs created above the height the equipment can reach.  Both an uneven silage face as well as a silage overhangs create a higher risk for avalanches.   As mentioned previously, as silage face/pile height increases, the potential force and impact of any avalanche also increases. Silage height determines a safe working distance from the silage face.  When a silage avalanche happens, the silage falls both down and out and upon impact spreads out, running away from the face.  For that reason, never stand closer to the silage face than three times its height.

In addition to removing silage from the face for daily feeding, other tasks may be pulling a silage sample for nutrient or dry matter analysis or pulling back plastic and/or removing tires covering the pile.  When collecting a silage sample for quality analysis, do not allow farm labor, nutritionists, or feed representatives to sample directly from the silage face.  Collect silage in a loader bucket and sample from that loader bucket after it has been moved a safe distance (at least 3x the pile height) from the silage face.  When removing plastic or tires from the pile do not permit persons to be working where silage overhangs exist.  Spoiled silage should not be hand-pitched off the top of the pile.  Remove spoiled silage with equipment operated from ground level. 

All labor on the farm, including family members, should be trained on silage feed out safety and made aware of the danger of silage avalanches.  I have some silage safety DVD’s from the Keith Bolson Silage Safety Foundation that I would be glad to provide to a farm for training and awareness purposes.  Contact me at the Wayne County Extension office, 330-264-8722.


Rory Lewandowski is an OSU Extension Agriculture & Natural Resources Educator and may be reached at 330-264-8722.

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