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 at an AD plant operation.

Dorchester Crown Court heard that two men were working at Lowbrook Farm, owned by Clifford Owen Yeatman where they were exposed to toxic gases during maintenance of an anaerobic digestion (AD) plant at the farm. The plant was developed by Biogas Nord UK, of which Mr Yeatman was sole director.

The men 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 one came round he found his colleague 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. The unconscious man was later declared dead without having regained consciousness.

An investigation by the HSE found a number of unsafe practices and failings during both the construction and operation phases of the AD plant.
It appears that Biogas Nord, did not assess the risks associated with the plant in general or with opening the roof. The roof had been opened five times leading up to a including the day of the incident; however it was not designed for routine removal and its opening should have been required only rarely had the plant been operating correctly.

The court heard that 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 by the business and the workers. The process should have been fully risk assessed and included a DSEAR assessment; had these been done by competent persons then this could have been avoided.

The HSE investigation identified that a previous similar incident had never been reported under RIDDOR as it should; then a worker fell unconscious after he was exposed to toxic gas when he was replacing the clamps that held the roof seal in place. The business had subsequently provided masks but failed to train the workers 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.

Clifford Owen Yeatman, of Lowbrook Farm, Blandford Forum, Dorset, was fined a total of £15,000 as a director of Biogas Nord UK (Ltd) after pleading guilty to two breaches of the Health and Safety at Work etc Act 1974. He also pleaded guilty to two further breaches of the act as a partner of CO and RA Yeatman and was fined £45,000. His company, Farmergy Ltd, also of Lowbrook Farm, was fined £10,000 after pleading guilty to breaching section 42 of the Health and Safety at Work etc Act 1974. Both Mr Yeatman and his company Farmergy Ltd were ordered to share £75,000 in costs.

The HSE commenting after the case indicated the importance of learning from experience and making sure that suitable controls are added.
As consultants we have seen the emergence of such AD operations and have provided DSEAR assessment services across a number of operations for the larger businesses. However farm energy generation from anaerobic digestion is an emerging application in the UK, and the businesses running these may not recognise the risks fully.

There is a history of risks associated with access to confined spaces and the associated potential for exposure to hydrogen sulphide in anaerobic digestion facilities. Additionally there are fire and explosion risks that need to be taken in to account.

Further information on the process of anaerobic digestion can be found on the HSE website at http://www.hse.gov.uk/waste/disposal.htm#anaerobic