The operator of a Victorian power station has been found guilty of putting staff and the public in danger after a coalmine fire raged for 45 days in and blanketed the community in thick smoke and coal dust.

Key points: The jury found the Hazelwood mine's sprinkler system was not adequate for the conditions and fire risks had not been properly assessed

The jury found the Hazelwood mine's sprinkler system was not adequate for the conditions and fire risks had not been properly assessed It also found that the Hazelwood Power Corporation did not have enough staff on hand to fight the 2014 fire

It also found that the Hazelwood Power Corporation did not have enough staff on hand to fight the 2014 fire Earlier this year, the power station's operators were found guilty of pollution offences arising from the fire

The ABC can now also reveal the Hazelwood Power Station operators were found guilty of pollution offences related to the 2014 fire, which started when two bushfires spread into the open-cut coal mine, in a trial earlier this year.

That trial was subject to non-publication orders while the subsequent trial took place.

Today, a Supreme Court jury found the Hazelwood Power Corporation did not adequately assess the risk of fire, did not have an adequate reticulated water system, failed to slash vegetation around the mine and did not take action early enough to wet down areas around the mine.

After an eight-week trial, jurors also found there were not enough workers at the site with the expertise to fight the fire on the day, and the company failed to adequately assess the risk of a fire entering the mine.

The company was charged with 12 offences and found guilty of 10.

The jury found the company not guilty of failing to provide decent generators or an alternative power source to operate the fire system.

The Hazelwood fire burned for 45 days, covering the Latrobe Valley in smoke. ( ABC News )

Company failed to maintain watering system

The trial decided today involved 12 charges brought by workplace watchdog WorkSafe Victoria against the Hazelwood Power Corporation.

During the trial, Crown prosecutor Sally Flynn QC argued the company should have foreseen the possibility of a fire entering the mine and the origin of the fire did not matter.

She said the watering system in the northern walls of the mine, known as batters, had fallen into disrepair after the mine was privatised in 1996.

She said as a result, it could not be used to reduce the risk of fire by wetting the coal or be used later to fight the fire.

Almost 10,000 metres of pipe had to be installed in the northern batters during the fire to fight it, she said.

Other charges related to creating risk by not adequately staffing the mine on the day the fire started and not maintaining vegetation inside the mine.

Two other charges relating to an alleged failure to maintain vegetation were dropped.

The town of Morwell was covered in a thick layer of smoke from the mine fire. ( ABC News )

Penalties from both trials will be determined at a later date.

Parent company ENGIE acknowledged the two sets of verdicts in a statement and said it would "consider our options and next steps".

"We again acknowledge the efforts of our workforce in successfully protecting the operating areas of the mine … and of the CFA and MFB," a companies spokesperson said.

"The Hazelwood mine fire was an unprecedented event arising from two rapidly moving, deliberately lit, external bushfires that approached the mine from different directions in what were extremely challenging conditions."

The Hazelwood Power Station was closed in early 2017 in a decision unrelated to the fire.

'Bad things happen'

The court heard there was a total fire ban on the day the fire started but only two extra emergency services staff were rostered on to deal with the increased risk of fire.

The company's barrister, Ian Hill QC, told the court the fire was a "rare, exceptional, unprecedented event" and one of the fires was started by arsonists.

"When bad things happen it doesn't always mean that someone is at fault and even if they are at fault it doesn't mean they're criminally at fault," he said.

Mr Hill told the court the company had conducted a review of major mining hazards in October 2012, which included fire.

He said even if a risk assessment for external fire was undertaken it "would not have led to any particular control being implemented, so as to eliminate or reduce risk".

Mr Hill said the company had identified heat, vehicles and electrical faults in the operating areas of the mine as the highest fire risk.

"They recognised that fire could occur and most likely would occur in the operational areas," he said.

"They had policy plans and procedures and training … to deal with combat the incidents of fire and they did so on a regular basis."

The secret trial

The first Supreme Court trial, which started in May and went for eight weeks, was kept secret so as not to compromise the jury in the second trial.

In July, a jury found a group of four companies guilty of a total of 12 charges.

Latrobe Valley residents told the first trial they suffered respiratory illness and nosebleeds as ash from the fire cloaked the town of Morwell. ( Supplied: Keith Pakenham, CFA )

Hazelwood Pacific, Australian Power Partners, Hazelwood Churchill and National Power Australia Investments — part of Hazelwood Power Corporation — were convicted of offences related to creating unsafe pollution around the town of Morwell.

The trial, before Justice Andrew Keogh, heard details of the health impacts members of the Morwell community experienced during and after the fire.

Simon Ellis told the court he watched the fire take hold in the mine from his balcony in Morwell.

Mr Ellis, who has since moved away from Morwell, developed a wheeze which he blamed on the smoke and said his young daughter suffered nosebleeds.

"I had these coughing fits that started. I would just cough and actually pass out from coughing, where I actually ended up going to hospital," he said.

'There was ash everywhere'

Another local explained how she lost her voice from working and living in the town during the mine fire.

"We were all sick from the fumes and from the smoke we'd inhaled," Michelle Gatt testified.

"There was ash everywhere. No matter how much I vacuumed or swept, you couldn't get rid of it and it continued to be like that for the next couple of weeks, probably four weeks."

Crown prosecutor David Neal SC argued the company failed to properly prepare for a massive fire and did not do enough to fight the fire when it did take hold.

Sprinkler systems failed to prevent the blaze from igniting the coalmine walls. ( Supplied: Keith Pakenham, CFA )

"The mine … failed to put in place sufficient reticulation, allowed vegetation to grow unchecked in the worked-out batters and failed to provide sufficient staff in light of all the resources that would be needed to meet such an attack," Dr Neal said.

"That's the reason that the pollution occurred.

"Thirty-five people on 9 February 2014 was never going to be enough people to deal with embers from a bushfire attack."

The companies' lawyer, Ian Hill QC, unsuccessfully argued the circumstances leading up to the mine fire were "freakish" and "extraordinary" and the company had prepared as well as could be expected.

"There were management structures, policies in place, well-trained, well-qualified people working at the Hazelwood mine in a professional way," Mr Hill said.

"The fires in the mine were caused by exceptional circumstances in extreme conditions where usual safety controls don't work.

"Never before had an arsonist or arsonists lit a number of fires driven by 70 to 80 kilometre per hour winds as those three fires lit along the Strzelecki-Driffield Road were."

A 'win for the people'

Wendy Farmer, from the Latrobe Valley community group Voices of the Valley called the verdict "exciting".

"It's part of the justice for the community," she said.

"It would be really be good now for Hazelwood Corporation and their partners to come out and apologise to our community.

"This is a win for the people of Latrobe Valley and Victoria."

Both the Environment Protection Authority (EPA) and WorkSafe Victoria applauded the verdicts.

"This verdict sends a clear warning to all employers that WorkSafe can, and will, prosecute them if they fail to put the safety of not only their workers, but also the community, first," a WorkSafe spokeswoman said.

