WorkSafe has charged civil construction company Pipecon over the deaths of two Ballarat workers who were killed when the trench they were working in collapsed on March 21 last year.

Key points: One man was killed instantly and another died in hospital after the trench collapsed

One man was killed instantly and another died in hospital after the trench collapsed Pipecon has been charged with failing to properly supervise its employees and failing to provide adequate safety equipment

Pipecon has been charged with failing to properly supervise its employees and failing to provide adequate safety equipment The families of the workers are campaigning for the introduction of industrial manslaughter laws

Charlie Howkins, 34, was laying pipes in the Ballarat suburb of Delacombe when the trench he was working in gave way, killing him instantly and trapping his 21-year-old colleague Jack Brownlee.

Heavy machinery was brought in to widen the trench to free Mr Brownlee, who was buried from the waist down in the five-metre-deep trench.

A worksite in Ballarat where a trench collapsed, resulting in the deaths of two workers. ( ABC News )

Mr Brownlee died in the Royal Melbourne Hospital the following morning, despite undergoing four operations.

Since the accident, Mr Brownlee's parents, Janine and Dave, and Mr Howkins' wife, Dr Lana Cormie, have been campaigning for the introduction of industrial manslaughter laws to hold employers accountable for the deaths of employees.

Ballarat company Pipecon has been charged with two breaches of the Occupational Health and Safety Act relating to its failure to use safety equipment, including trench shields and manhole cages to protect workers from engulfment during the excavation.

The breaches also relate to the company's failure to provide supervision to ensure employees were working with the safety equipment.

Pipecon managing director Andrew Mahar said in a statement he had worked closely with authorities to determine what led to the "tragic accident".

He said he would continue to do so "in a bid to ensure such an incident never happened again either at Pipecon or any other construction company".

The statement said the company would not make further comment while the accident was subject to a WorkSafe review or before the courts.

The matter is due to be heard in the Ballarat Magistrates' Court on February 4.