It’s not a daily task, but it’s a fundamentally critical one to get right. You’ve no doubt heard tragic pit-pumping stories where a farmer, family member or employee has asphyxiated or succumbed to toxic gases from a livestock manure pit.

When present in sufficient concentration, hydrogen sulfide, carbon dioxide, methane and ammonia can be lethal to workers and pigs. However, by ensuring that no people remain in the barn and that there is proper ventilation management during pit pumping, you can minimize the danger.

“Hazardous gases not only lurk within the pit but can also permeate buildings when pits are agitated during pumping,” warns Dee Jepsen, Ohio State University agricultural safety specialist. Jepsen urges producers to become familiar with the dangers before an emergency arises.

Four gases of particular concern when addressing manure-pit safety are hydrogen sulfide, carbon dioxide, methane and ammonia.

  • Hydrogen sulfide is highly toxic and the most dangerous of all manure gases. High concentrations can deaden your sense of smell, and just a few breaths can cause you to lose consciousness and result in death.
  • Carbon dioxide results from manure decomposition and animal respiration. The gas is heavier than air. Inadequate ventilation means carbon dioxide can displace oxygen and cause asphyxiation.
  • Methane is odorless and colorless; it can displace oxygen and cause asphyxiation and explosions.
  • Ammonia is a lighter gas that has a characteristic urine smell. “Ammonia causes less of an immediate concern because the strong, persistent odor discourages long contact,” Jepsen explains.

Planning ahead and being well prepared to pump pits can save time, reduce risks and ensure safety for all.

There are several steps to take before a pit-pumping crew arrives or you begin the process yourself.

”Never allow people in a barn that is being pumped,” cautions Mike Brumm, Brumm Swine Consultancy. “It’s just too dangerous.” He recommends using yellow police tape or setting up a barrier on all facility entrances prior to pumping. The Minnesota Pork Board also has developed and made available a new pit-pumping warning door tag. (See sidebar below.)

Brumm suggests that a trained employee be positioned within the operation site during pit pumping to connect with first responders if an emergency arises. That person must have contact information for emergency and rescue personnel, as well as the operation’s management.

The next critical step before pumping begins is to be sure all fans are functioning properly. Do this well ahead of the actual pumping process so that any needed repairs can be done before pumping is scheduled.

When the pit-pumping crew arrives, they usually require you to sign a waiver, removing them from liability, should any pigs die. Make sure the appropriate person is available for this step.

Brumm emphasizes that fresh air and ventilation are crucial. “During pit pumping, the goal in managing the ventilation system is to have fresh air to disperse to all parts of the barn,” he says. “Also, minimize the amount of incoming air coming up through the open pit port covers.”

Brumm cites a University of Minnesota study which looked at pig deaths associated with pit pumping. It revealed that 94 percent of pig deaths occurred during aggressive pit agitation and 67 percent of those were on relatively calm days. “Pig death usually results from lack of air movement and ventilation in the pig zone,” Brumm points out.

If manure is right up to the top of the slats, don’t agitate the slurry until you have 1 to 2 feet of space under the slats so that fans can remove the gas. Otherwise all of the gases released from agitation will end up in the pig zone. “When stirring, keep the agitation stream under the surface to help reduce gas release,” Brumm adds.

Gases, including hydrogen sulfide, are released rapidly when the manure is agitated. If animals are present, avoid aggressive surface agitation, often called rooster-tailing.

There are several ways to improve ventilation during pit pumping; Brumm offers the following advice.

Curtain Barns

  • In cold weather with big pigs:

- Leave curtains closed and operate all exhaust fans.

- Reduce static pressure in the pig zone by opening ceiling inlets slightly to allow less air to be drawn from port openings into the animal space.

  • In cold weather with small pigs:

- Due to the risk of chilling, running fans at 50 percent capacity may be sufficient.

- Stirring fans, if used, must be aimed parallel with the ceiling. Downward pointing stir fans may bring additional manure gases up from the pit. Continue running stir fans for one to two hours after the pump-out has been completed.

  • In warm weather with big or small pigs:

- If there is a wind at 5 miles per hour or greater moving the air, open curtains and operate all fans.

 - On calm days with no wind, close curtains and operate all exhaust fans.

Tunnel Barns

  • In cold weather:

- All pit fans should be functioning in addition to the 36-inch fan.

- Open the tunnel curtain 6 to12 inches so the 36-inch fan can pull air the length of the barn to reduce the likelihood that a hydrogen sulfide pocket will form.

- Reduce static pressure so that inlet velocity is 300 to 400 feet per minute as opposed to the standard 800 feet per minute.

- If ceiling inlets are powered, partially close the inlets so air must enter from the tunnel curtain.

  • In hot weather:

- Operate all pit fans and at least two tunnel fans.

- Manage ceiling inlets and tunnel curtains similar to the cold-weather recommendation.

- Continue to ventilate for one to two hours after the pump-out has been  completed.

These are guidelines. If you have a contract operation that has designated standard operating procedures for pit pumping, be sure to follow the steps outlined. 

After the pit pumpers leave, walk the perimeter and make sure that all pit covers are in place and secured. If necessary, use spray foam to repair cracks or chips and insure a tight seal.

With careful planning, proper scheduling and following strict procedures, you can keep workers safe and help prevent pig deaths. Make sure workers are warned to stay out of facilities during pit pumping procedures. By keeping people out of the building and ensuring proper air movement and ventilation during and following pit pumping, you will significantly reduce the hidden hazard of pit gases.

 Keep Them Out

 The Minnesota Pork Board and University of Minnesota Extension swine specialists have developed a warning tag to hang on barn doors where manure pit pumping is scheduled. The tag has an area for management to list dates and times involved and deters workers from entering when pit pumping is occurring

For more information, or to order free safety tags, contact one of these organizations:

  • The Minnesota Pork Board, (507) 345-8814
  • The Iowa Pork Producers Association, (515) 225-7675
  • The Illinois Pork Producers Association, (217) 529-3100
  • Elsewhere in the United States, call the National Pork Board, (800) 456-PORK.

It’s suggested to hang one tag on each door that opens to the barn. To print out your own version, click here.