Yorkshire Water has been fined £733,000 and ordered to pay costs of £18,818 after a worker suffered fatal burns during a job in Tadcaster.
Leeds Crown Court heard how Michael Jennings’ clothes caught fire while removing valve bolts at the Tadcaster sewage works on 20 July 2015.
He suffered whole body burns and died in Pinderfields Hospital two days later.
Jennings was a mechanical fitter in the engineering reliability team and had worked for Yorkshire Water for eight years.
Yorkshire Water pleaded guilty to breaching Section 2(1) of the Health and Safety at Work Act 1974.
An investigation by the Health and Safety Executive (HSE) found that the valve at the water treatment plant was half open and sparks reacted with high oxygen levels.
John Micklethwaite, HSE inspector described the incident as “wholly avoidable”.
Meanwhile Yorkshire Water’s chief executive Richard Flint, said the company “must ensure” it does everything possible to prevent something like this happening again.
Jennings was working at the bottom of a dry well on the end of the disused lane one of the brewery trade waste treatment plant at the Tadcaster sewage treatment works. The adjoining lane two was still in service.
The brewery trade waste plant was the only Yorkshire Water Services effluent treatment plant to use oxygen gas injection to assist the clean-up process, according to the HSE.
Jennings and a colleague had been tasked with changing the stop valve on the end of the disused lane one drain pipe which emerged into the bottom of the dry well.
He was using an angle grinder to cut through corroded bolts when sparks from the grinding wheel impinged onto his overalls, bursting into flames.
The HSE said it found that the drain valve was half-opened and the atmosphere within the dry well was oxygen-enriched, greatly increasing the risk of fire.
A near miss report had also been recorded at the same location in September 2014.
Employees had found the interior of lane one to be heavily oxygen-enriched and had alerted local managers to the problem. Following this near miss the company carried out an investigation but reached the wrong conclusion that the oxygen enrichment was due to residual oxygen and that the issue had been resolved, the HSE’s investigation found.
This had implications for future work in that Yorkshire Water proceeded on the basis there was no further risk of oxygen enrichment within lane one.
The HSE investigation showed that the company’s risk assessment and permit to work procedures had been inadequate. There were no site-specific procedures in place and the generic risk assessment template form did not include oxygen enrichment as a possible hazard.
The employees working on the day of the incident were not familiar with the site and they were not aware of the previous near miss. This meant that they did not have the knowledge or experience to recognise that oxygen-enrichment of the dry well was a potential hazard when the valve was taken off or opened.
Following the hearing HSE inspector Micklethwaite, said: “This was a tragic and wholly avoidable incident, caused by the failure of the company to implement an adequate and effective safe system of work for work in a confined space.
“Those in control of work activities have a duty to identify hazards that could arise, to eliminate or to mitigate them, and to devise suitable safe systems of work. The risk assessment process is central to this role.
“The employer also has a duty to provide the necessary information, instruction and training to his workers, and to provide an appropriate level of supervision to ensure that the work can be carried out safely and without risks to health.”
Responding to the incident, Yorkshire Water’s chief executive, Richard Flint, said the tragic event had a “profound effect” on the company.
He added: “Whilst we cannot change what happened to Mick, we must ensure this terrible accident leaves a permanent legacy on the business and that we do everything possible to prevent something like this happening again.
“There is nothing more important to us than ensuring that each and every one of our colleagues returns home safely to their families after their day’s work.
“We have already done a significant amount of work to transform how we approach health and safety, but we are committed to constantly working to ensure that we have the best possible systems in place to make sure that nobody else has to experience what Mick’s family have been through.”