by Sally Colby
Rob Meinen, senior extension associate, Penn State University, has been spreading the word about manure for a long time, but he says there’s still a lot to learn when it comes to manure safety.
“Manure incidences often go unreported,” said Meinen. “Loss of consciousness occurs without a report. I know of six people who have gone through an unconscious phase at some point during manure storage; four of them with liquid systems and two with solid manure in the poultry industry.” Meinen added that most deaths of heifers, dairy cows and finishing hogs related to manure handling also go unreported.
It’s important to remember that all manures are organic material undergoing microbial degradation. “Whether it’s solid or liquid, hot or cold outside, gasses are a by-product of those processes,” said Meinen. “The five gasses we often refer to are hydrogen sulfide, ammonia, methane, lack of oxygen and carbon dioxide.” Meinen reminds farmers that other gasses can accumulate and create dangerous conditions.
Confined spaces are another safety issue, and include open-air storage as well as storage that is obviously confined. Meinen says the accepted definition of a confined space is one that is large enough to enter but has limited access and exit, and not designed for continuous normal occupancy by a worker. “The pit access of a sow barn or the door to a grain bin are recognized by most people as confined spaces,” said Meinen. “Neither one of these spaces are designed for normal occupancy.” Meinen compares these spaces to the typical outdoor manure pit surrounded by a fence, which can also be dangerous. “Once we cross the fence at this storage, where we have blue skies and lots of wind, we are in a confined space. Open-air storages do need respect.”
Different gasses behave differently, and handlers and haulers should understand the properties of manure gasses. Some gasses are odorless, most are colorless and some are explosive. “It’s important to realize that gasses can stratify,” said Meinen. “Hydrogen sulfide is heavy, and it sinks. It will stratify and be in a low area.”
Gasses can also rise. Meinen describes an incident that occurred at a swine-finishing farm in an empty barn. The fans were off to save energy and the producer was washing the barn and knocking back foam that was in the under-floor manure storage pit. “He was unknowingly releasing methane,” said Meinen. “The methane rose to the ceiling, the heater kicked on that day (in winter) and a ball of fire went through the barn.” The producer suffered third-degree burns, and the metal roof buckled.
Some characteristics of manure can increase risk. “Liquids trump solids,” said Meinen. “Liquids are more dangerous and represent more risk than solid manures.”
Meinen uses the visual of a front-end loader pushing into a pile of solid manure in cool weather and the subsequent release of steam. “All manures need respect, and that release of steam is a perfect visual of how the gasses can come off and create a bloom.” Meinen added that it isn’t clear which manure represents a higher risk — swine liquid or dairy liquid — but it’s clear that anaerobic conditions are worse than aerobic conditions. Anaerobic situations occur very quickly in a liquid system, anaerobic microbes are more likely to produce hydrogen sulfide, and deep storage facilities have a lot of time to create dangerous gasses.
Moving manure greatly increases the release of gas. “Agitation is an especially risky time,” said Meinen, adding that it’s important to consider solid manure risk as well. “Not only are we changing the surface concentration of ammonia or any other gas, but we’re also increasing the effective surface area of the gas, and the flux rate greatly increases.”
Meinen explains flux as the action of flowing, such as with ammonia. Another type of movement is ebullition, which is the loss of gas through bubbling. “Some gasses release through ebullition,” said Meinen. “Hydrogen sulfide is the most important one we worry about; methane and carbon dioxide also emit this way.”
To further explain ebullition in relation to manure storage, Meinen says microbes produce gasses during metabolism, which are excreted into manure. “The gasses eventually become thick enough in a concentration that’s high enough that they exceed their individual gas solubility in that solution,” he said. “Once these gasses exceed their solubility, they create a bubble, and that bubble can jump up to the surface. That may or may not create foam.”
Warm weather greatly increases the risk of agitating or handling manure. A 2007 study showed that 60 percent of incidences occurred between May and August, with 26 percent, or one in four, occurring in August. Meinen explained that storages are often empty in spring, crops are planted and growing and cropland is not available for manure application. This means manure must be stored, sometimes for months. “Storages accumulate a mass of manure that is anaerobic, it’s the warmest time of year so microbes are very active,” he said. “That anaerobic manure is also undisturbed, so gasses build up.”
A fact that applies to all of agriculture, including manure handling, is that complacency kills. Meinen says it isn’t uncommon to hear people say they’ve ‘gone in to make repairs many times’ or ‘he has agitated that manure storage many times and we haven’t had an issue.’ “Our normal daily practices need to prevent risk if we can,” said Meinen. “This is one time when the agricultural work ethic can backfire.” Farms that develop standard operating procedures for manure can help increase worker safety.
The operator position should always be up and away, and resist the temptation to reach over an edge to adjust or maintain machinery. “Choose an upwind position,” said Meinen. “If we are designing and constructing storages, offer several options so no matter what day it is, we can get there to access the manure storage and still be upwind at all times. Be aware of areas that trap gas.”
For optimum safety, Meinen recommends handlers wear a monitor and observe agitation from a distance. The use of switches allows the operator to shut down agitation without being close to the pit. While the first hour of agitation carries the most risk, handlers should never become complacent, and should be aware of the health and safety of nearby people or livestock. Proper barriers and locks to manure storage facilities should be standard operating procedure.
Although wearing a monitor to detect gas would save lives, Meinen realizes not everyone follows that recommendation. He suggests awareness of body alarms that can signal gas exposure. Body alarms includes dizziness, wobbly knees, feeling hot and clammy, lack of attention to details, loss of motor skills/fatigue, anxiety/excitement, severe eye irritation/decrease in vision, headache, nausea/vomiting, shortness of breath, panting, pausing/stopping of breath, respiratory tract irritation/coughing, tightness of chest, acute bronchitis, asphyxiation and loss of consciousness.
Most importantly, adults should make choices for children. “We can understand, we can accept responsibility and educate kids but also make choices for them,” said Meinen. Statistics show that 21 percent of fatalities were people under age 16, and 11 percent of victims are listed as ‘playing and discovered missing’. All were children.