The boss of an oil refinery where four workers were killed and another was seriously injured in an explosion has apologised for the failings that led to the disaster.
Dennis Riley, 52, Robert Broome, 48, Julie Jones, 54, and 33-year-old Andrew Jenkins died when a storage tank exploded at the Chevron plant in Pembroke in June 2011. A fifth worker, Andrew Phillips, suffered life-changing injuries.
The oil firm, along with contractors B&A Contracts, are in the dock at Swansea Crown Court being sentenced for breaches in health and safety law.
Mark Ellison QC, barrister for the refinery – which is now operated by Valero – read a statement to court from the general manager of the plant at the time of the blast, Greg Hanngi.
In it the manager said he was conscious that "merely saying sorry" was of no comfort to those affected by the blast but that it was important an apology was made in open court to all those concerned and to the wider community.
He said he offered his "deep regret and sincere apologies" for the firm's failings which did not prevent the explosion and he said the failings had "let down" those killed and injured and their families.
Four deaths and horrific burns to survivor at oil plant happened after 'series of errors'
Apologies were also given on behalf of B&A Contracts, a tank-cleaning firm working at the refinery.
The firm's barrister, Prashant Propat QC, described the events of June 2 as an "horrific, tragic, preventable incident" which killed four, caused serious injury, and ruined the lives of "many, many people".
The barrister said the boss of B&A, Brian Summons, was "deeply remorseful and regretful" and wanted him to "say sorry as many times as I can".
Mr Propat read a statement from the firm's owner in which he said he thought about the events at the refinery every day and wished he could turn back time and stop them happening.
He said he wanted to make it clear the workers on the day had done nothing wrong and the failures were the company's and the company's alone rather than the tank-cleaning team's.
Mr Summons said it was clear the firm had not done enough to understand the risks at the refinery and added: "I will regret that for the rest of my life."
In the early evening of June 2, 2011, a massive explosion ripped through a storage tank at the refinery's amine recovery unit (ARU) as workers from B&A Contracts were emptying it prior to cleaning.
While sludge was being pumped from the bottom of the tank flammable vapours inside ignited, blowing the roof off, destroying the large vessel, and causing a large fireball which engulfed the area.
Those killed and seriously injured were all involved in the pumping process and were working near the tank when the explosion happened.
The terrible day a massive explosion killed four oil refinery workers
Mr Ellison, for Valero, said the firm accepted in its guilty pleas that there were "systemic failures" stemming from changes in the way chemicals used in the cleaning of crude oil was handled – changes which had been introduced in 1998.
Prior to that date amine which was heavily contaminated with flammable hydrocarbons had been dealt with off-site but the decision was made to introduce a "closed system" and keep it within the plant's ARU.
Mr Ellison confirmed there was no evidence of a risk assessment having been done on the changes in amine handling at the time and he said the firm accepted there had been a failure to address the "underlying cause" of contamination of the ARU storage tank by light hydrocarbons in the years that followed the introduction of the new system.
The judge, Mr Justice Lewis, described this as "13 years of continuous failure". Mr Ellison again confirmed the firm accepted there had been "systemic failures".
The barrister also accepted the storage tanks in the ARU had been wrongly categorised during a hazardous area classification review in 2008 as "non-hazardous".
The Valero barrister invited the court to find that working procedures for the job being undertaken on the day in question were in place but were not being followed, with people instead "using their own judgement" based on their experience.
He described the events which happened in the run-up to the explosion as a "unique situation" and said of the day: "There are some aspects of quite bizarre human behaviour."
Mr Propat, for B&A, said the firm accepted it had not followed its own procedures, had supplied a non-earthed hose for the pumping work failed, had failed to provide proper supervision, and had failed to ensure key staff we aware of the relevant industry standards.
He said while the firm were specialist tank cleaners it was not the company's job to ascertain there was nothing unsafe inside.
He said: "Chevron were responsible for handing over a safe tank before B&A started work on it."
The judge said it seemed to him there were a number of occasions in the run-up to the explosion when the tank-emptying job should have been "stopped in its tracks".
This included the fact the man originally tasked with overseeing the job went on holiday and said in a phone call the emptying should be postponed until his return but that message was mistakenly linked to a different tank in the refinery.
Additionally a gas test on the day showed high levels of flammable vapours in the tank but there is a lack of agreement about what happened to this information, though it seems the result was written on a piece of paper which was subsequently thrown away. Mr Justice Lewis said he thought it was incredible that gas test results were not routinely logged or formally recorded.
When the contractors began work on the tank there was still a quantity of liquid inside and a witness reported how, when a side access was opened, the liquid came gushing out and "the boys were literally swimming in it". However the sludge-removal job went ahead anyway.
The court heard details of two previous convictions involving Texaco (the previous name for Chevron) and Valero. In 2016 the firm was fined £400,000 after the collapse of a dockside gantry which resulted in a man suffering crushed legs and in 1994 it was fined £200,000 after a "large explosion" at the Milford refinery when liquid hydrocarbons were wrongly pumped into a closed vessel.
The court also heard Valero has already come to an agreement with the Health and Safety Executive to contribute £1m towards the cost of its prosecution.
Valero Energy UK Ltd and B&A Contracts have both previously pleaded guilty to two offences each under the Health and Safety at Work Act.
The judge is expected to pass sentence in June.
