Mine owner Bloomfield Group has declined to comment on the contents of the report, which describes the work that Mr Norman and two colleagues were engaged in at the time of his death as “unplanned, ad-hoc and unsupervised”.

As the regulator established in the weeks after Mr Norman’s December 13 accident, he and his colleagues had begun cleaning remnant coal from the trucks with shovels, rather than hosing them out as they had done in the past.

The new report says: Mr Norman reported to [his employer, mine sub-contractor] Simmons that someone from the mine had told him he was not allowed to use the wash bay to clean out the inside of the coal haulage trailers anymore due to coal getting into the sump.”

Despite the protest of one co-worker, Mr Norman said he would get inside the truck to clean it, and used a steel spanner with a 1.250mm long “pipe wrench or breaker bar” to prop open the tailgate.

“This tool had been on the site for many years and was used by Mr Norman for several different functions that he carried out at the mine site,” the report says. 

Having successfully cleaned one truck this way, Mr Norman and his workmates began on a second but he “had trouble getting the prop in place while the tailgate was being held open”.

“Mr Norman and two other workers attempted to manually clean out another coal haulage trailer using the same method between 9.00am and 9.30am.

“However, Mr Norman had trouble getting the prop in place while the tailgate was being held open. The tailgate fell and Mr Norman’s head was crushed between the tailgate and the rear of the trailer body causing serious head injuries.”

He was treated at the scene and flown to hospital but died two days later.

The final page of the report lists eight causal factors – mainly a lack of procedures, training, risk assessment and communication with management  – it says were part of a “culmination of events that resulted in the incident occurring”.

Although the decision to take the work away from the usual wash bay was not examined in the report, it does say that “the use of the wash bay would have eliminated or minimised the risk”.

“The workers were not adequately trained in hazard identification and risk control,” the report says.

“The workers were not adequately supervised. The implementation of the safety management system and procedures concerning contractor management was not effective.”

The report makes no mention of prosecutions or legal action but a spokesperson for the regulator said that investigations were about to be finalised.