Civil construction firm Pipecon has pleaded guilty to a charge over a trench collapse that killed two workers. 

Jack Brownlee, 21, and Charlie Howkins, 34, died while carrying out high-risk excavation work at the Winterfield housing estate at Delacombe on Ballarat's outskirts in March 2018.

A trench the two men were working in collapsed, causing Mr Howkins to die at the scene. Mr Brownlee was trapped for three hours and died in hospital from his injuries the following day.

Industrial manslaughter laws were introduced in Victoria in the wake of the deaths.

The Victorian County Court heard this week that none of the required safety measures were in place when the men entered the trench.

Pipecon was charged in 2019 with two occupational health and safety offences over the deaths - failing to provide a safe workplace and failing to provide supervision to ensure a safe workplace.

The company initially pleaded not guilty, but has now pleaded guilty to one charge of failing to provide supervision to ensure a safe workplace.

Pipecon's defence barrister, Stephen Russell, said the guilty plea was entered in the hope of “easing distress” for the victim's families.

Prosecutors have withdrawn the other charge.

Ballarat Trades and Labour Council secretary Brett Edgington has welcomed the progress.

“For the families, just hearing Pipecon get up and admit guilt I think was a very profound moment,” Mr Edgington told the ABC.

“I'm very glad they got to hear those words spoken in court.

“We've just seen how awful that system is for everybody involved — the fact that it's taken three years, the fact that we've got into a sort of bargaining position on the charges.

“One thing that has come out of this tragedy is the families of Jack and Charlie have fought so hard that other families will never have to go through this process again if they have a loved one that's been killed at work.”

A plea hearing that will include victim impact statements from both men's families has been listed for October.