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Understanding manure storage system safety risks

Confined manure systems present myriad safety risks. Ensure you and your staff are aware and well-prepared.

November 29, 2020  by Tracey Erickson, SDSU Extension

Photos courtesy of Tracey Erickson.

Are you at risk while pumping out your manure storage system? Without throwing out the “here’s your sign” card, the simple answer to the question posed in the title of this article is: yes! Many producers know and understand the risks associated with confined manure handling systems, but accidents and deaths still occur because unwarranted risks are taken as manure is handled and removed from the confined manure handling systems.

Ask yourself these questions: Does every employee understand the risks associated with confined manure handling systems? Have they received proper training when dealing with confined manure handling systems? Do you have the appropriate hazard signage posted near the confined manure handling system, warning people of the dangers? Do you have the appropriate safety gear available and have you provided instruction to employees on using the equipment? Do you have employees with limited English-speaking skills? Do they fully understand the safety risks and signage provided? Do employees and family members have the ability to communicate location directions in an emergency 911 call?

These may seem like simple things; unfortunately, they often go overlooked. We assume that everyone should know the risks and know what to do in an emergency. Taking the time to provide proper safety equipment and educate employees and family members about the correct safety protocols around confined manure handling systems helps prevent deaths and accidents.

Understanding the Risks

So, what is the risk with confined manure handling systems? Understanding that there is risk associated with manure pits and manure lagoons is important. They both produce toxic gases as the manure undergoes anaerobic digestive fermentation. The gases produced and the characteristics of each are below:


Methane: Methane is an odorless gas that is flammable or explosive at concentrations of five to 15 percent by volume of air. The gas is lighter than air and typically found near the top of the pit, and high enough concentrations can cause death by suffocation.

Hydrogen sulfide: Hydrogen sulfide is an extremely toxic gas with a “rotten egg” smell at low concentrations; at high concentrations, it can paralyze the olfactory senses. It is heavier than air and often settles towards the bottom of the manure pit. At low concentrations, it can cause dizziness, headache, nausea and respiratory tract irritation. At high concentrations, it can cause unconsciousness, respiratory failure and death within minutes. It is also explosive at various concentrations.

Carbon dioxide (CO2): Carbon dioxide is an odorless gas that is heavier than air and often settles near the bottom of the manure pit. At low concentrations, it causes labored breathing, drowsiness and headaches. In high concentrations, it can displace enough oxygen and cause death via suffocation.

Ammonia (NH3): Ammonia has sharp odor characteristics that irritate the eyes, nose, throat and lungs. Exposure to high concentrations can be fatal.

Besides understanding the various types of gases produced in confined manure handling systems, you should also follow these guidelines when working around confined manure handling systems.

Manure Pits

These are enclosed manure storage structures, which should be equipped with ventilation systems. They are often found in dairies as manure is pumped out to a lagoon, in confined swine operation buildings, or certain types of beef finishing operations that utilize a confined building.

  • Keep all manure pits ventilated and fans working properly.
  • Keep all manure pits covered with appropriately ventilated grating.
  • Post hazard signs near all manure pit entry point locations.
  • Never enter a manure pit unless absolutely necessary and only when proper safeguards are utilized.
  • If entry into the pit is necessary, test the air for toxic gases.
  • Never enter a manure pit unless someone is standing by and maintaining constant contact. The person standing watch should be able to lift an unconscious person wearing a safety harness attached to a lifeline. They should never enter the pit trying to rescue someone. They should have the ability to communicate necessary information in case of an emergency 911 call.
  • Always wear a safety harness attached to a mechanical device such as a winch, hoist or pulley. This is your lifeline, so the person on the outside must maintain constant contact with the lifeline.
  • Always wear a positive-pressure, self-contained breathing apparatus (SCBA).
  • Provide a powered, explosion-proof air ventilation system for each manure pit that will help bring in a continuous fresh air supply.
  • Never enter a manure pit to attempt a rescue without a safety harness and proper respiratory protection.

Manure Lagoons

Manure lagoons also produce toxic gases in localized layers, which – especially on hot, humid days with little breeze – can cause a health hazard and potential death. Gases are readily released when lagoons are agitated to remove manure to be incorporated as fertilizer into the fields. They often have a thick liquid, floating crust, which can make swimming and buoyancy difficult if you were to slip or fall into the lagoon. Additional safety guidelines for manure lagoons are as follows:

  • Open-air lagoons should be fenced off around the perimeter with locked access gates to keep unauthorized people or unwanted animals from accidentally entering them.
  • Hazard signs should be posted at entry points warning of toxic gases and drowning dangers.
  • Wear a safety harness attached to a lifeline with someone on the other end that can drag you out if it is necessary to enter the lagoon.
  • Rescue equipment, such as flotation devices and lifelines, should be attached to every manure pump.
  • Move slowly around manure lagoons as the ground can be uneven, causing a person to trip and fall.
  • Never work alone, but all other unnecessary bystanders should stay away from access points or pump-out points.
  • No horseplay allowed in these areas.
  • No smoking or open flames allowed near agitation or pumping areas due to the explosive gases that may be present.
  • If equipment breakdown occurs during agitation or pumping, shut it down and remove it from the lagoon area before servicing.
  • Follow the same 911 emergency call guidelines as manure pits: be able to describe the situation, number of victims, location and directions.

Safety is not a choice. It is something that we need to practice on a daily basis in agriculture. Enclosed manure holding facilities are one of many areas in livestock operations that have inherent risks. However, by following these recommended safety guidelines and training all involved we can be safer and live to see another day with loved ones and family.

Editor’s note: This article was originally published by SDSU Extension and republished with permission.


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