What you can't see can kill you
ARLINGTON - When Cheryl Skjolaas was growing up, her family had the first open air manure storage system in Dane County to go with their parlor and barn scraper.
“My mom’s fear was always that we’d find a dead body in the manure lagoon when we pumped it out,” she recalls with a smile.
Luckily that never happened, but Skjolaas may have inherited her mother’s concern for farm safety. As a faculty member at the UW-Madison’s Biological Systems Engineering department, she has become one of the state’s foremost experts on farm safety.
Recent tragedies involving manure lagoons and under-barn manure storage have prompted her and colleagues at UW-Extension to work on a new publication “Reducing Risks from Manure Storage Agitation Gases” which is available at all county extension offices or by calling 1-877-947-7827 or accessing www.learningstore.uwex.edu.
She spoke about the care that needs to be taken when dealing with manure storage at the recent North American Manure Expo held at the UW’s Arlington research farm. There has been a string of deaths related to breathing manure lagoon gases – 2- and 4-year-old brothers were found dead after playing near a manure structure; more recently a young beef producer in Wisconsin in August 2016 died near an open air manure storage structure.
In that case the gases also killed a number of animals on the farm. “This case has us talking,” Skjolaas said.
There appeared to be something about Midwestern weather conditions last fall that was a factor. In October 2016, she said, more than 60 steers died in Wisconsin, Illinois and Iowa in naturally ventilated barns with manure pits under the barns.
Regardless of weather conditions or whether the pits are outside or inside, she said, it’s impossible to know if the ventilation – natural or mechanical – is doing what it’s supposed to do without a monitoring system. This is especially true once the manure pits are being agitated.
Once agitation begins the “crust” on the manure is broken and it gives gases a way out. While gases escape a manure pit or lagoon all the time, they are most likely to concentrate and reach dangerous levels during agitation, which is done to suspend solids and blend in the liquids before and during the land spreading process. The most dangerous of the gases for human and animal safety is hydrogen sulfide.
Other gases are also present. Methane can be explosive. Carbon dioxide can replace oxygen and can drop available oxygen levels, causing asphyxiation. Ammonia is a respiratory irritant, she said and can be felt in the eyes and lungs with the potential to do permanent damage.
But hydrogen sulfide – the gas that at some concentrations can smell like rotten eggs – is heavier than air. Because of its properties it will hang in greater concentrations in the barn.
Farmers and manure handlers, she said, should not rely on the “rotten egg” smell to tell them of the presence of hydrogen sulfide. At low levels people can perceive the odor, but at higher levels it can affect the nerve related to the sense of smell and prevent people from smelling the highly toxic gas.
High concentrations of hydrogen sulfide, typically seen during agitation of manure storage units, can cause a person to stagger and collapse within five minutes. Higher concentrations lead to rapid unconsciousness and death within minutes. Concentrations which reach 1000 to 2000 parts per million will instantly cause death.
For the young Wisconsin beef producer who lost his life last year, Skjolaas said there were a number of factors. The air was calm, there was no wind to dissipate emissions and there was what weather experts call an inversion in place, which “put a lid” on the gases and held them close to the ground, like putting a lid on a cooking pot, she said. Also, agitation helped direct the gases to his location.
The first strategy in dealing with gas dangers, or any other kind of farm safety situation, Skjolaas said, is to eliminate the hazard altogether. One of the things that can be done to reduce manure gas risk is to agitate when temperatures are lower. Research shows that when temperatures are below 64 degrees F hydrogen sulfide emissions are greatly reduced.
But that’s no guarantee of safe emissions. The amount of hydrogen sulfide released by agitating manure also depends on the amount of sulfur content in the manure and the pH. Predicting gas emissions from a given manure structure is difficult to do.
If a hazard can’t be eliminated the next step is to conduct training and education to protect people who may be in contact with it. In the case of manure gases, she recommended using personal protective equipment to reduce risk and monitoring equipment to alert workers if gas levels rise.
She demonstrated various kinds of meters that can be used to detect these deadly gases. One is a small yellow device about the size of a small phone that clips onto a person and will sound the alarm if the air turns deadly.
A four-gas multi-meter, which simultaneously monitors for oxygen, hydrogen sulfide, ammonia and methane is best, she said, although these kinds of meters are the most expensive. They can be used around the work site in areas of the highest risk – near the controls of the agitator or tractor to sound the alarm.
The smaller, personal devices can be purchased for as little as $150. She also recommended that people working around these danger zones carry small self-contained respirators with a bottle of breathable air that can be used in case an alarm sounds. It’s important to note that the kinds of respirators or masks that protect people from dust or filter other contaminants from the air will provide no protection from deadly hydrogen sulfide or situations with low oxygen levels.
Some of the alarm devices Skjolaas demonstrated can be linked by Bluetooth to smart phones to send a text message to another person in case of a problem. She said these meters can be lifesavers when farmers or manure haulers enter confined spaces like manure reception areas or manure spreaders.
The so-called deep pits for storing manure under barns have caused safety problems for people and livestock in the past. This kind of manure storage can cause dangerously high gas levels, especially when the manure is being agitated. Experts recommend that people and animals be removed from these barns when manure gets agitated. Additional ventilation is also recommended for these systems.
Skjolaas said that it’s important to plan ahead, including an escape route, in case of problems that may arise during the agitations and hauling out of liquid manure. The plan should be shared with everyone who will be involved in the process or near the facility, including outside contractors like manure haulers.
The emergency plan should include what will happen if someone should succumb to gas while in the process of agitating or loading manure. The plan to rescue a downed worker should include the rescuer wearing a self-contained breathing apparatus to avoid multiple workers being taken down by the gas.
For further information on manure gas safety, visit http://fyi.uwex.edu/agsafety.