Working with Slurry

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ONE BREATH CAN KILL – slurry gas at the right concentration will kill.

Many people have drowned in or been asphyxiated by slurry or slurry gas. Often a second person trying a rescue is killed too.

Fence off lagoons, pits and tanks to stop anyone falling or climbing in. The standard of fencing should be very secure.

Keep everybody well away from areas that store slurry.

Carefully plan slurry stirring and pumping tasks. Keep unauthorised people away.

Mix/stir on a windy day, always mix from a position outside any building. Stirring inside a building needs more safety measures and should be avoided.

Gas is released as soon as mixing starts.

No one should have access to the area where slurry is being stirred until at least 30 minutes after the work is complete.

What is Slurry Gas

Slurry gas is a mixture of gases – the most dangerous gas is hydrogen sulphide which is extremely poisonous. At a low concentration this gas will attack your sense of smell so you won’t even know it’s there.

At higher concentrations you will, very quickly, find it harder to breathe and become confused and collapse.

At certain concentrations ONE BREATH CAN KILL.


  • Ensure any fences have been designed to deter access and are properly erected and maintained and that any access points such as gates or apertures for suction pipes should be protected to the same standard as the remainder of the fence or wall.
  • Ensure gates are designed to prevent unauthorised opening. Fit chains and padlocks or other locking mechanisms and keep them locked.
  • Avoid stacking materials against any fence, wall or above-ground storage tank in such a way that they provide a means of climbing over it and remove all ladders that give access to storage tanks when they are not in use.
  • If you scrape manure over a ramp into a lagoon or pit, your ramp will normally need a barrier to stop tractors or other machines going over the edge.


  • Take all animals out of the building before starting to mix slurry.
  • If possible, mix on a windy day.
  • Open all doors and windows so buildings are very well ventilated.
  • Use outside mixing points. Don’t use indoor mixing points unless very strict controls are in place.
  • If slats are removed, cover exposed openings of the tank beside the pump/mixer to stop anything falling in.
Start the pump/mixer and then KEEP OUT of the building for as long as possible – or for at least 30 minutes or longer after the stirring stops.
Poisonous gases are released in large volumes very soon after mixing starts and in a confined space can build up to dangerous levels very quickly.
Keep away from openings buildings and tanks for a minimum of 30 minutes after slurry stirring stops.
  • Don’t enter buildings above slurry storage during mixing. This is a specialist work and you will need breathing apparatus (a face mask will not work).
  • Because of high gas concentrations, do not stand over any mixing point inside or outside of the building when the mixer is running.
  • DO NOT stand close to the pump/exhaust of a tanker when it is being filled.
  • Have tanks emptied before the slurry gets up to within 300mm of the slats.


What about masks and gas monitors/meters?

  • Face or filter type masks are not suitable when working with slurry.
  • Gas monitors and detectors should not be used as the only means of providing the right level of safety in order to protect you from exposure to slurry gases, particularly hydrogen sulphide. Slurry gases are produced at fatal concentrations very quickly, often before a monitor can react. Gas detection systems also require expert maintenance, calibration and storage.

What about clearing blockages or entering tanks?

  • Entry into confined spaces such as slurry tanks is specialist work and involves a very high level of training, planning and specialist breathing and rescue apparatus. Always leave it to fully trained, competent contractors.
  • Your sense of smell will not protect you. Hydrogen sulphide inactivates your sense of smell.
  • Remove all sources of ignition from mixing areas. Some slurry gasses are flammable.

What if there is an accident or someone has collapsed?

  • Don’t go into any building or store. Stay outside. If possible stop the pump.
  • DO NOT put yourself at risk – people have died trying to save others. Phone 999 or 112 and get PROFESSIONAL/EMERGENCY SERVICES help.
  • When you call 999/112 – explain the nature of the injury, especially if the victim is unconscious or not breathing. Always remember to specifically say SLURRY is involved as this will ensure the emergency services send the right people with the right equipment (this helps prioritise the type and speed of responder).


  • Train everyone involved in work with slurry and set up and test emergency procedures.
  • Make sure everyone carries a mobile phone with them and have the relevant emergency information and emergency contact numbers programmed into them.





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dan parrWorking with Slurry