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Bunker Silo Safety

A bunker silo looks simple, but the face of stored feed can collapse and vehicles working on top can roll. This guide describes the hazards and points to official resources.

What is a bunker silo?

A bunker silo is a trench-like structure with walls on two or three sides in which chopped forage is packed and covered. It is open at one end and at the top, so people often do not think of it as a confined space.

It still carries serious hazards, including face collapse, vehicle accidents, falls from the walls and gases around the stored feed.

Ask your extension office about guidelines for building and maintaining bunker silos in your area, since structure design affects safety.

• Open at the top and one end
• Walls that can be high
• Heavy packed feed

Why is the silage face dangerous?

Feed at the open face can be tall, heavy and unstable. Pieces can break away without warning, especially if the face has been cut unevenly or is overhanging. A person standing near the face can be buried or struck.

Safety educators recommend keeping people out of the zone in front of a high face and following a plan for how feed is removed. Details about face management come from extension and your equipment manuals.

A face that is cut in layers from top to bottom, rather than undercut, generally behaves more safely, but follow the official guidance for your equipment and feed. Never allow a person to work alone at the face. If something goes wrong, someone has to call 911 immediately.

• Overhangs and uneven faces
• People working or standing below
• Loose feed that falls unexpectedly

What about vehicles on the pile?

Tractors and loaders packing feed work on sloped surfaces next to walls, which is a recipe for rollover. Drivers have limited visibility, and bystanders can be struck or run over.

Keep people on foot away from working equipment. Use a spotter or other agreed communication when needed, and make sure operators are trained and rested.

Operators should be trained and should not be asked to work beyond their skill, particularly on a sloped surface.

• Keep people on foot away from working equipment
• Train and rest operators
• Use a spotter or an agreed signal

What are the fall hazards?

Walls and edges can be high, and covering the pile requires people to work near the edge, sometimes on slippery plastic. Falls from heights can cause serious injury.

Ask your extension office or OSHA about fall protection approaches suited to your structure. Do not decide that a short fall is unimportant.

A fall from a wall can happen quickly, especially when covers are wet or icy.

• Cover work near walls and edges
• Wet or icy plastic is slippery
• Ask OSHA about fall protection options

Does gas matter at a bunker?

Fermentation gases can collect in low places near the silage, particularly around covered feed or in nearby enclosed spaces. The open design reduces the risk compared with a tower silo, but it does not remove it.

Treat unusual symptoms such as dizziness or coughing near stored feed as a reason to get to fresh air and seek medical advice.

Warning symptoms should never be shrugged off. Seek medical care if you feel unwell after working near stored feed.

• Dizziness near stored feed means move to fresh air
• Cough or sore throat should be checked
• Tell a doctor about silage exposure

How do you keep children and visitors safe?

Bunkers attract curious children, who may climb, play on the cover or approach the face. Fence or close off the area when you are not working, and teach everyone that it is not a play area.

Visitors, delivery drivers and part-time helpers should be told where they may and may not go.

Locked gates, signs and clear rules all help, but supervision is the surest way to keep children safe.

• Fence or close off the bunker when not in use
• Tell visitors where not to go
• Supervise any young workers closely

Where can you learn more?

Extension programs in dairy and beef regions publish guidance on safe feed storage and removal. OSHA and NIOSH provide general agricultural safety information.

If someone is buried by feed or injured in a rollover, call 911 right away. Do not dig or climb into unstable feed to rescue them.

Local fire departments can also help by learning the layout of your bunkers in advance.

• Call 911 for burial or rollover
• Do not climb into unstable feed
• Ask extension for local training

Last reviewed: November 12, 2026. Written by the Farm Safety Editorial Team. See our editorial policy.