Each farm should have safety protocols for manure storage systems. A farm safety checklist is a good start to developing a specific plan for your operation.
Manure agitation and pumping is typically a short window of time during busy spring and fall seasons. While manure gases are always present when there is stored manure, the danger level for hydrogen sulfide and methane, in particular, are elevated when manure is being agitated.
Manure pumping activities may only involve a small set of people from on or off your operation. However, all on-farm family and staff should be aware of these dangers of manure gas exposure, and how to reduce the risks to human and animal health and safety. For example, all need to be aware of what signs mean and what to do when they come across one. Another example is manure transfer pits may be a distance from the actual manure storage area, but gases may be released at this point.
General safety preparations for manure agitation and pumping on farm are evacuate – extinguish – signage – ventilate.
When stored manure is agitated or pumped from under the slatted floor of a barn, remove all people from the barn. If possible, remove the animals. Once people are evacuated, signage (discussed later) and barriers reduce the risk of re-entry before it is safe to do so. For outdoor manure storage areas, the only people around the area should be those who are moving the manure.
Remove any potential ignition sources to guard against flash fires and explosions. Turn off power to any non-ventilation equipment and extinguish any pilot lights or other ignition sources.
Place warning signs at all entrances to buildings and storage areas where manure agitation is occurring. This ties back to making all on-farm family and workers aware of procedures, even those who may not be directly involved with manure removal. Make sure they are all aware what this activity means, what the potential dangers are, so that all people respect and follow the signs.
Monitor wind conditions, and particularly wind inversions, when pumping from outdoor manure storages.
For barns, a ventilation strategy during manure pumping needs to be dynamic and considerate of the day-to-day temperature, wind conditions and barn type. In an ideal world, we can remove animals from barns before manure agitation and removal. However, we recognize that animal removal is not always possible. Turning off pilot lights to reduce ignition sources takes heaters offline. This is an important safety step, but in cool weather can translate to chilly conditions for young animals. Therefore, a ventilation strategy also needs to consider the stage of production and animal environment.
For deep pit swine and dairy barns, manure pump-out ports are often located and accessed under pit ventilation fans. Taking ventilation fans offline reduces the ventilation capacity. These large openings can also influence airflow patterns and distribution. Air will take the path of least resistance, and air may short-circuit through these openings rather than coming through curtain wall or ceiling inlets. Covering these openings around the pumping equipment, if possible, reduces the influence the opening has on the air flow patterns in the barn and animal area.
When pit ventilation is in place, remove manure at least two feet below the bottom of the floor slats before agitation to ensure ventilation in the animal zone during agitation events. If the manure is too high, pit fan ventilation does not effectively move air from the animal zone, and increases the risk of gas exposure.
Table 1 is a quick glance overview of ventilation strategies during manure pumping to optimize airflow through the animal occupied zone and temperature for animal comfort for wean-finish swine operations. Similar principles, but different ventilation rates apply to dairy and beef cattle barns.
Table 1. Ventilation strategies during manure pumping to optimize airflow and temperature for wean-finish swine
|Barn type||Weather conditions||Stage of production||Ventilation strategy||Implications/considerations|
|Tunnel ventilated barn||Cool weather||All||Provide a minimum of 25-30 cfm per pig, starting with pit fans and adding wall fans as needed||Reduce static pressure by increasing the curtain inlet opening and reducing the ceiling inlet area Aim for 300-400 fpm airspeed at the curtain inlet|
|Tunnel ventilated barn||Warm weather||All||Provide a minimum of 30-35 cfm per pig, starting with pit fans and adding wall fans as needed||Reduce static pressure by increasing the curtain inlet opening and reducing the ceiling inlet area Aim for 300-400 fpm airspeed at the curtain inlet|
|Curtain-sided barn||Cool weather||Smaller pigs||Leave curtains closed and provide a minimum of 25-30 cfm per pig||Reduce static pressure by increasing inlet opening area Air velocity and distribution in the animal zone may be compromised|
|Curtain-sided barn||Cool weather||Larger pigs||Leave curtains closed and operate all exhaust fans||If ventilation capacity is reduced by over half, open curtains|
|Curtain-sided barn||Warm and windy||All||Open curtains and operate all exhaust fans|
|Curtain-sided barn||Warm and calm||All||Leave curtains closed and operate all exhaust fans||If ventilation capacity is reduced by over half, open curtains|
Table adapted from Pit Pumping Guidelines produced by Brumm and Harmon.
Reviewed in 2019