C4-MR-3-MANUREDEMO1by Steve Wagner
“If you drop your monkey wrench, you could bend down to pick it up, and be in a dangerous place.” With that statement, Rob Meinen, senior extension associate at Penn State’s Department of Animal Science, essentially described the tone of the seminar this day at Pleasant View Dairy Farms LLC in Pine Grove, PA. Looking at a soon-to-be-filled lagoon surrounded by cyclone fencing, he further cautioned heightened awareness to match an increasing threat. “We need to be aware that an outdoor storage like this should be considered a confined space. Confined spaces are not designed for normal worker occupancy.”
Concerns here, he says, mirroring the concerns of all attending, “stem from manure gases that can be deadly and cause injury; deadly, in the worst case scenario, of course.”
While not exactly a spike in manure illness or death statistics, there has been a recent subtle increase in manure-related farm accidents — enough for ag specialists to be looking for suspects as to why. And they have found some. One, in particular, is gypsum and its use as a bedding amendment, or as straight bedding, for dairy farms, where some deaths have occurred. “In Pennsylvania and Maryland,” Meinen notes, “these multiple situations, including children who were found unconscious but revived, are alarming.” Gypsum bedding, on the positive side, is ideal. It absorbs moisture. It is an inorganic substance with low bacteria counts. Many farmers like the fact that somatic cell counts have decreased. And it is a great soil amendment. On the other hand, gypsum is calcium sulfate and, therefore, provides a source of sulphur which, under anaerobic conditions, can be converted to hydrogen sulfide gas. This heavier-than-air gas is released in bursts during manure movement or agitation. Gypsum bedding increased this gas. Manure storage amendments, or additives, have demonstrated an ability to reduce these gas emissions. Manure handling, environmental conditions and manure character also influence these gas levels.
Operators with the highest gas (H2S) exposure were very close to agitation. The first 30 to 60 minutes of agitation is the most dangerous even near open air outdoor manure storages, namely lagoons. “If the dairy industry hasn’t been aware, they are becoming aware of hydrogen sulfide gas,” said Mike Hile, the project coordinator and a Ph.D. candidate in agricultural engineering. “Typically, in the past, I think a lot of injuries and deaths have been attributed to methane gases. The real risk of hydrogen sulfide is that it is very dangerous at low levels; 100 parts per million (ppm) is immediately dangerous to life and health. The real concern is during agitation events. Once the hydrogen sulfide is generated within the manure storage and that manure is moved around, when the crust is moved, big plumes of dangerous levels of gas get to escape. If you’re in that environment, it could be a hazard.”
Penn State agricultural engineer Eileen Fabian offered a brief primer on hydrogen sulfide gas. “It smells like rotten eggs,” she said. “At 10 ppm, which is the exposure limit for a day’s work, the rotten egg smell is evident. Once you get up to 100 ppm, where it is dangerous for you, you lose the ability to detect that smell. That’s what makes it tricky here.” In other words, if you can’t smell it, either it is a very high content, or perhaps it has disappeared. “Listen to your body alarms,” added Meinen. “Sometimes that can be tightness in the chest, a sense of asphyxiation, headache, dizziness, wobbly knees or nausea. Any gas that is not oxygen can kill you if it displaces oxygen. We all breathe out carbon dioxide with every breath we take. But if that is all there is in our room, with no oxygen, that carbon dioxide could be deadly to us.”
Awareness is a prime key. Farm owner Eric Wolfe has an 11-year-old son who pilots the tractor and other farm equipment and is trained to pay heed to the signals. But Eric still takes no chances. When the tractor and agitator are positioned at the lagoon entrance, the cyclone fence doors are shoved up against the tractor to prohibit any forgetful or unintended entry. If body alerts and common sense fail to engage, then there are gas detection devices that can be positioned about the area on tripods or clipped onto fences or belts that will beep reminders of impending danger. At one point, about a dozen such pager-sized devices engaged in a symphony of cautious beepery as the lagoon neared full capacity. Gas detection specialist Mike Platek of Industrial Scientific made it his concern to see that outmoded alarms were replaced by his more sensitive ones. An EMT said he had been trained to use atropine as a treatment for silo gas, but he wondered about treatment for hydrogen sulfide gas. The answer was fresh air, or oxygen, if fresh air isn’t enough, and they talked about two children who had been overcome by the gas. “They recovered very quickly as soon as they got the fresh air,” one man said. “The older of the two children immediately recovered. The younger child, however, stayed unresponsive for about 20 or 30 minutes,” and was kept overnight at a medical facility.