Federal workplace safety regulator Comcare has filed legal proceedings against two employers over workplace incidents in Adelaide.

Comcare has filed complaints and summonses in the Adelaide Magistrates Court against waste management company Transpacific Industries and construction company John Holland.

Transpacific faces two charges, and John Holland three charges of breaching the Commonwealth Work Health and Safety Act 2011 over separate incidents within 24 hours of each other in Adelaide in 2013.

Each offence carries a maximum penalty of $1.5 million.

The charges against Transpacific relate to a fire at its Wingfield Chemical Waste Processing Plant near Port Adelaide on 25 July 2013.

Comcare alleges that Transpacific workers were conducting the company's first production-scale trial to distil a new industrial solvent from a chemical waste product when a flash fire broke out from a large distillation tank.

The force of the fire knocked a worker to the ground from a distance of around five metres, and he was treated in hospital for burns.

The John Holland matter involved an accident the following day, 26 July 2013, at the South Road Superway construction project in Adelaide's north.

The alleged incident occurred when a portal crane collided with an elevated work platform. The worker in the basket of the elevated work platform received medical treatment for his injuries.

It is alleged that both companies failed to ensure, so far as was reasonably practicable, the health and safety of their workers and exposed them to a risk of death or serious injury or illness.

The matters will be heard in the Adelaide Magistrates Court.