Taken from the HSE website,
"A Dorset farm owner and his two businesses have been fined for serious safety failings after a 29 year-old worker died following exposure to toxic gases.
"Matthew Pitt and David Bartlett were exposed to toxic gases during maintenance of an anaerobic digestion (AD) plant...... Mr Pitt and Mr Bartlett, both from Sturminster Newton, were tasked with opening the roof of the digester tank to free a stirring mechanism which had stopped moving due to a crust forming in the tank. As they did so, they were engulfed by toxic hydrogen sulphide gas.
"Both men lost consciousness and when Mr Bartlett came round he found Mr Pitt lying next to him but could not get a response. He alerted other people on site to get help and an ambulance was called. Two paramedics and two other farmworkers also suffered from the effects of the fumes. Mr Pitt was later declared dead without having regained consciousness.
An investigation by the Health and Safety Executive (HSE) found a number of unsafe practices and failings during both the construction and operation phases of the AD plant.....
"Workers were not trained to remove the roof and did not recognise that the removal of the roof was a specialist job. The risks from substances generated in the AD process, including explosion and exposure to toxic gases, were poorly understood.
Work at height during the removal of the roof was also carried out without adequate safety precautions.
The investigation identified that a previous similar incident had never been reported to HSE. On 1 August 2008 farm worker Joerg Grondke fell unconscious after he was exposed to toxic gas when he was replacing the clamps that held the roof seal in place.
While masks were supplied after the 2008 incident workers were never trained in their use and they were taken off once the roof was removed in the mistaken belief that the danger had passed. The masks were also not face-fitted or properly maintained.
"Matthew Pitt’s mother, Janet Pitt, said:
" “I have still not come to terms with the loss of our son. Matthew was not just a son, but a best buddy too. We were a close-knit farming family that did everything together. We lived, worked hard and played together. All that has ended and although we carry on with our lives, behind the strong exterior lies broken hearts that will never be mended.” "
More information about this incident can be found on the HSE website.
Information on the process of anaerobic digestion can be found here.