Safe Handling of Slurry
In Ireland, over 40 million tonnes of slurry are stored, handled and spread each year. Working with slurry is a particularly hazardous activity. The two risks when working with slurry are the risk of drowning in slurry tanks and the risk of asphyxiation by toxic gases released from slurry in storage.
Drowning in slurry and water, and asphyxiation (gas poisoning), caused 14% of farm deaths between 2000 and 2009.
Accident statistics now indicate that drowning in slurry storage tanks is the cause of more fatal accidents than poisoning by slurry gases.
1.Toxic gases
Toxic gases are released during the bacterial decomposition of slurry in tanks.
Inhaling these gases which include hydrogen sulphide, ammonia, methane and carbon dioxide can be lethal.
Some, like methane, are flammable. One in particular, hydrogen sulphide, is poisonous. All these gases are heavier than air, so they displace oxygen. This can lead to suffocation when a person enters a tank.
Hydrogen sulphide is extremely poisonous both to people and animals. It affects the nervous system and small concentrations can cause death. There have been many incidents in which people were overcome by slurry gases. Several people have been killed.
Smell is no indicator of the absence of gas, as many gases are odourless. Hydrogen sulphide has a ‘rotten egg’ smell at low levels, but cannot be smelt at higher levels. High levels can be released when slurry is agitated.
One breath or lung-full at this level causes INSTANT death.
Highest risk when slurry is being agitated. The gases are trapped in the slurry and are released when it is mixed. Studies indicate that levels are greatest shortly after mixing commences in the tank, when slurry is stored for several months, when slurry is mixed in deep tanks, after silage effluent is added and when slurry is mixed in cold weather.
Prevention
Evacuate and ventilate before you agitate.
Never agitate slurry in still air conditions.
Move all animals out of the shed before commencing.
At least two people should be present at all times.
Keep children and elderly persons away from the area when agitating.
Open all doors and outlets to provide a draught.
Never stand over slats or near tank access points when agitation is in progress.
Avoid vigorous agitation in confined spaces.
Do not allow slurry to rise within 300mm of the slats or tank covers.
Keep all people away from the agitation point for 30minutes after starting agitation.
Never enter the slurry tank unless you are wearing suitable breathing apparatus and/ or a harness attached to a lifeline controlled by at least two other adults positioned outside of the area.
Where possible agitate from the outside the building.
Avoid smoking or the use of naked lights as slurry gases are highly flammable.
Gases can build up and remain in partially emptied tanks above the slurry, never enter a tank for any reason.
Put up warning signs to warn of the dangers when working with slurry.
2.Drowning
Drowning is by far the most common cause of death involving slurry. Children and the elderly are at particular risk.
In the period 2000-2010 30% of child fatal accidents on farms were caused by drowning in slurry or water. In the same period 8% of deaths to elderly farmers were caused by drowning.
Prevention
Open slurry tanks should be protected by an unclimbable fence or wall at least
1.8 metres high, with locked gates.
Scrape holes on outdoor lagoons should be adequately protected.
When the tank has to be emptied, consider having an adequately constructed access platform with safety rails.
Covered or slatted tanks require access manholes that children cannot open easily. Fit a safety grid below the manhole to give secondary protection.
Cover all slurry tank manhole openings. Adults and children have fallen into unprotected openings with fatal consequences.
Beware of the risk of back injury if you need to lift slats in the shed.
Guard the PTO on the slurry tanker and agitator– do not use unless correctly guarded. A high proportion of PTO entanglements occur when using slurry tankers.
Agricultural contractors must be aware of the dangers of working with slurry and should ensure that they work safely at all times.
Drowning in water
Several people were drowned in water on farms in recent years. Where possible, fence off water hazards and take a cautious approach when working near water tanks, ponds, rivers or lakes. Children are particularly at risk.
