Why slurry tanks are dangerous

A slurry pit is a hole, dam, or circular concrete structure where farmers gather all their animal waste together with other unusable organic matter, such as hay and water run-off from washing down dairies, stables, and barns. This is in order to convert it, over a lengthy period of time, into fertiliser that can eventually be reused on their lands to fertilize crops.

The decomposition of this waste material produces deadly gases, making slurry pits potentially lethal without precautions such as the use of a breathing apparatus with air supply. There is no such thing as a safe slurry tank, as incidents involving slurry occur regularly on farms in Great Britain including people, not just farmers, being overcome by toxic gases.

This is because during decomposition slurry is broken down by bacterial action which produces gases that settle in a thick cloud and can kill humans and animals almost instantly. Slurry gas includes methane, carbon monoxide and ammonia all of which create a risk to health. Some are flammable and others are toxic, displacing oxygen from the air and causing a risk of asphyxiation.

As soon as the slurry is mixed, toxins can be released very quickly and precautions need to be taken to protect from dangerous gases. For safety, slurry should only be mixed when doors and windows are open and when there are high winds so that fumes can be dispersed in the air. People should also stay out of the building for as long as possible when the slurry mixers are running, and all livestock should be moved out.

This gas rapidly displaces air from the lungs and affects the nervous system. Some gas may bubble to the surface but most remains dissolved in the liquid in a similar way to gas held within a bottle of fizzy drink.

As soon as slurry mixing starts, the gas is released rapidly. The addition of other materials such as silage effluent may increase the quantity of gas produced. The rate of gas release is variable and difficult to predict, adding to the danger. At high concentrations it is not possible to smell hydrogen sulphide. The gas is generally given off in large volumes very soon after mixing starts in any area of the tank. The first 30 minutes are the most dangerous. As mixing continues, the quantity of slurry gas released falls off.

However - each time the pump is repositioned to mix another part of the tank, gas concentration rises again. Stay out of the building for at least another 30 minutes or longer depending on the size of the tank. Slurry pumps that are designed to allow the PTO shaft to remain attached to the tractor when the pump is being transported have a high centre of gravity and it is important to follow the advice below:.

It is essential that the two lower lift arms on the tractor are properly latched and locked into the two brackets on the slurry pump linkage frame before the top link or PTO shaft are attached.

Gas concentration is measured, using special equipment, in parts per million of the atmosphere - ppm. Wearing a facemask will not help, according to the Health and Safety Executive. Anyone entering a slurry tank must wear breathing apparatus with its own air supply, it says.

If possible, slurry should be mixed on a windy day so that fumes can be more easily dispersed in the air. Doors and windows should be kept open and tank openings should be properly covered. The advice is that people should stay out of any building while slurry mixers are running for as long as possible. The use of meters to monitor gas levels are recommended only as an extra precaution, but the Health and Safety Executive says these are no substitute for proper safe working methods.

A common theme in the reaction by Northern Ireland politicians was how the fatal accident in Dunloy highlighted the continual dangers faced by farmers. Agriculture is an important part of the local economy, and it has brought a high cost as well in terms of human life. The incident on Saturday is the latest in a long line of fatal accidents involving slurry tanks on Northern Ireland's farms. The most high profile one happened in September , when Ulster rugby player Nevin Spence, his father Noel and brother Graham died after they were overcome by fumes on their family farm.

Slurry Safety Download sign Slurry presents two particular safety and health problems - drowning and gas poisoning. Open slurry tanks should be protected by an unclimbable fence or wall at least 1. Fit a safety grid below the manhole to give secondary protection. A high proportion of PTO entanglements occur when using slurry tankers.

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